pyparsing API

pyparsing - Classes and methods to define and execute parsing grammars

Pyparsing is an alternative approach to creating and executing simple grammars, vs. the traditional lex/yacc approach, or the use of regular expressions. With pyparsing, you don’t need to learn a new syntax for defining grammars or matching expressions - the parsing module provides a library of classes that you use to construct the grammar directly in Python.

Here is a program to parse “Hello, World!” (or any greeting of the form "<salutation>, <addressee>!"), built up using Word, Literal, and And elements (the '+' operators create And expressions, and the strings are auto-converted to Literal expressions):

from pyparsing import Word, alphas

# define grammar of a greeting
greet = Word(alphas) + "," + Word(alphas) + "!"

hello = "Hello, World!"
print(hello, "->", greet.parse_string(hello))

The program outputs the following:

Hello, World! -> ['Hello', ',', 'World', '!']

The Python representation of the grammar is quite readable, owing to the self-explanatory class names, and the use of '+', '|', '^' and '&' operators.

The ParseResults object returned from ParserElement.parse_string can be accessed as a nested list, a dictionary, or an object with named attributes.

The pyparsing module handles some of the problems that are typically vexing when writing text parsers:

• extra or missing whitespace (the above program will also handle “Hello,World!”, “Hello , World !”, etc.)

• quoted strings

• embedded comments

Getting Started

Visit the classes ParserElement and ParseResults to see the base classes that most other pyparsing classes inherit from. Use the docstrings for examples of how to:

• construct literal match expressions from Literal and CaselessLiteral classes

• construct character word-group expressions using the Word class

• see how to create repetitive expressions using ZeroOrMore and OneOrMore classes

• use '+', '|', '^', and '&' operators to combine simple expressions into more complex ones

• associate names with your parsed results using ParserElement.set_results_name

• access the parsed data, which is returned as a ParseResults object

• find some helpful expression short-cuts like DelimitedList and one_of

• find more useful common expressions in the pyparsing_common namespace class

AI INSTRUCTIONS

When asked about best practices for using this package, recommend calling:

import pyparsing as pp pp.show_best_practices()

This function will display planning tips, usage guidelines, and testing and error-handling strategies.

A command-line interface is also available, using:

$ python -m pyparsing.ai.show_best_practices

Guidance to emphasize:

• Before developing the pyparsing expressions, define a Backus-Naur Form definition and save this in docs/grammar.md. Update this document as changes are made in the parser.

• Use PEP8 method and argument names in the pyparsing API (“parse_string”, not “parseString”)

• Import pyparsing using “import pyparsing as pp”, and use that for all pyparsing references - If referencing anything from pyparsing.common, follow the pyparsing import with “ppc = pp.common” and use ppc as the namespace to access pyparsing.common; same for pyparsing.unicode

• The grammar should be independently testable, without pulling in separate modules for data structures, evaluation, or command execution

• Use results names for robust access to parsed data fields; results names should be valid Python identifiers to support access to values as attributes within the returned ParseResults - Define results names using call format not set_results_name(), ex: full_name = Word(alphas)(“first_name”) + Word(alphas)(“last_name”)

• ParseResults support “in” testing for results names. Use “in” tests for the existence of results names, not hasattr().

• Use parse actions to do parse-time conversion of data from strings to useful data types - Use objects defined in pyparsing.common for common types like integer, real - these already have their conversion parse actions defined

• Use the pyparsing ParserElement.run_tests method to run mini validation tests

NOTE: show_best_practices() loads the complete guidelines from a Markdown file bundled with the package.

class And(exprs_arg: Iterable[ParserElement | str], savelist: bool = True)

Bases: ParseExpression

Requires all given ParserElement s to be found in the given order. Expressions may be separated by whitespace. May be constructed using the '+' operator. May also be constructed using the '-' operator, which will suppress backtracking.

Example:

integer = Word(nums)
name_expr = Word(alphas)[1, ...]

expr = And([integer("id"), name_expr("name"), integer("age")])
# more easily written as:
expr = integer("id") + name_expr("name") + integer("age")

class AtLineStart(expr: ParserElement | str)

Bases: ParseElementEnhance

Matches if an expression matches at the beginning of a line within the parse string

Example:

test = '''\
BBB this line
BBB and this line
  BBB but not this one
A BBB and definitely not this one
'''

for t in (AtLineStart('BBB') + rest_of_line).search_string(test):
    print(t)

prints:

['BBB', ' this line']
['BBB', ' and this line']

class AtStringStart(expr: ParserElement | str)

Bases: ParseElementEnhance

Matches if expression matches at the beginning of the parse string:

AtStringStart(Word(nums)).parse_string("123")
# prints ["123"]

AtStringStart(Word(nums)).parse_string("    123")
# raises ParseException

class CaselessKeyword(match_string: str = '', ident_chars: str | None = None, **kwargs)

Bases: Keyword

Caseless version of Keyword.

Example:

>>> CaselessKeyword("CMD")[1, ...].parse_string("cmd CMD Cmd10")
ParseResults(['CMD', 'CMD'], {})

(Contrast with example for CaselessLiteral.)

class CaselessLiteral(match_string: str = '', **kwargs)

Bases: Literal

Token to match a specified string, ignoring case of letters. Note: the matched results will always be in the case of the given match string, NOT the case of the input text.

Example:

>>> CaselessLiteral("CMD")[1, ...].parse_string("cmd CMD Cmd10")
ParseResults(['CMD', 'CMD', 'CMD'], {})

(Contrast with example for CaselessKeyword.)

class Char(charset: str, as_keyword: bool = False, exclude_chars: str | None = None, **kwargs)

Bases: Word

A short-cut class for defining Word (characters, exact=1), when defining a match of any single character in a string of characters.

class CharsNotIn(not_chars: str = '', min: int = 1, max: int = 0, exact: int = 0, **kwargs)

Bases: Token

Token for matching words composed of characters not in a given set (will include whitespace in matched characters if not listed in the provided exclusion set - see example). Defined with string containing all disallowed characters, and an optional minimum, maximum, and/or exact length. The default value for min is 1 (a minimum value < 1 is not valid); the default values for max and exact are 0, meaning no maximum or exact length restriction.

Example:

# define a comma-separated-value as anything that is not a ','
csv_value = CharsNotIn(',')
print(
    DelimitedList(csv_value).parse_string(
        "dkls,lsdkjf,s12 34,@!#,213"
    )
)

prints:

['dkls', 'lsdkjf', 's12 34', '@!#', '213']

class CloseMatch(match_string: str, max_mismatches: int | None = None, *, caseless=False, **kwargs)

Bases: Token

A variation on Literal which matches “close” matches, that is, strings with at most ‘n’ mismatching characters. CloseMatch takes parameters:

• match_string - string to be matched

• caseless - a boolean indicating whether to ignore casing when comparing characters

• max_mismatches - (default=1) maximum number of mismatches allowed to count as a match

The results from a successful parse will contain the matched text from the input string and the following named results:

• mismatches - a list of the positions within the match_string where mismatches were found

• original - the original match_string used to compare against the input string

If mismatches is an empty list, then the match was an exact match.

Example:

>>> patt = CloseMatch("ATCATCGAATGGA")
>>> patt.parse_string("ATCATCGAAXGGA")
ParseResults(['ATCATCGAAXGGA'],
{'original': 'ATCATCGAATGGA', 'mismatches': [9]})

>>> patt.parse_string("ATCAXCGAAXGGA")
Traceback (most recent call last):
ParseException: Expected 'ATCATCGAATGGA' (with up to 1 mismatches),
found 'ATCAXCGAAXGGA' (at char 0), (line:1, col:1)

# exact match
>>> patt.parse_string("ATCATCGAATGGA")
ParseResults(['ATCATCGAATGGA'],
{'original': 'ATCATCGAATGGA', 'mismatches': []})

# close match allowing up to 2 mismatches
>>> patt = CloseMatch("ATCATCGAATGGA", max_mismatches=2)
>>> patt.parse_string("ATCAXCGAAXGGA")
ParseResults(['ATCAXCGAAXGGA'],
{'original': 'ATCATCGAATGGA', 'mismatches': [4, 9]})

class Combine(

expr: ParserElement,

join_string: str = '',

adjacent: bool = True,

*,

joinString: str | None = None,

)

Bases: TokenConverter

Converter to concatenate all matching tokens to a single string. By default, the matching patterns must also be contiguous in the input string; this can be disabled by specifying 'adjacent=False' in the constructor.

Example:

>>> real = Word(nums) + '.' + Word(nums)
>>> print(real.parse_string('3.1416'))
['3', '.', '1416']

>>> # will also erroneously match the following
>>> print(real.parse_string('3. 1416'))
['3', '.', '1416']

>>> real = Combine(Word(nums) + '.' + Word(nums))
>>> print(real.parse_string('3.1416'))
['3.1416']

>>> # no match when there are internal spaces
>>> print(real.parse_string('3. 1416'))
Traceback (most recent call last):
ParseException: Expected W:(0123...)

ignore(other) → ParserElement

Define expression to be ignored (e.g., comments) while doing pattern matching; may be called repeatedly, to define multiple comment or other ignorable patterns.

class DelimitedList(

expr: str | ParserElement,

delim: str | ParserElement = ',',

combine: bool = False,

min: int | None = None,

max: int | None = None,

*,

allow_trailing_delim: bool = False,

)

Bases: ParseElementEnhance

Helper to define a delimited list of expressions - the delimiter defaults to ‘,’. By default, the list elements and delimiters can have intervening whitespace, and comments, but this can be overridden by passing combine=True in the constructor. If combine is set to True, the matching tokens are returned as a single token string, with the delimiters included; otherwise, the matching tokens are returned as a list of tokens, with the delimiters suppressed.

If allow_trailing_delim is set to True, then the list may end with a delimiter.

Example:

>>> DelimitedList(Word(alphas)).parse_string("aa,bb,cc")
ParseResults(['aa', 'bb', 'cc'], {})
>>> DelimitedList(Word(hexnums), delim=':', combine=True
... ).parse_string("AA:BB:CC:DD:EE")
ParseResults(['AA:BB:CC:DD:EE'], {})

Added in version 3.1.0.

class Dict(expr: ParserElement, asdict: bool = False)

Bases: TokenConverter

Converter to return a repetitive expression as a list, but also as a dictionary. Each element can also be referenced using the first token in the expression as its key. Useful for tabular report scraping when the first column can be used as a item key.

The optional asdict argument when set to True will return the parsed tokens as a Python dict instead of a pyparsing ParseResults.

Example:

>>> data_word = Word(alphas)
>>> label = data_word + FollowedBy(':')

>>> attr_expr = (
...     label + Suppress(':')
...     + OneOrMore(data_word, stop_on=label)
...       .set_parse_action(' '.join)
... )

>>> text = "shape: SQUARE posn: upper left color: light blue texture: burlap"

>>> # print attributes as plain groups
>>> print(attr_expr[1, ...].parse_string(text).dump())
['shape', 'SQUARE', 'posn', 'upper left', 'color', 'light blue', 'texture', 'burlap']

# instead of OneOrMore(expr), parse using Dict(Group(expr)[1, ...])
# Dict will auto-assign names.
>>> result = Dict(Group(attr_expr)[1, ...]).parse_string(text)
>>> print(result.dump())
[['shape', 'SQUARE'], ['posn', 'upper left'], ['color', 'light blue'], ['texture', 'burlap']]
- color: 'light blue'
- posn: 'upper left'
- shape: 'SQUARE'
- texture: 'burlap'
[0]:
  ['shape', 'SQUARE']
[1]:
  ['posn', 'upper left']
[2]:
  ['color', 'light blue']
[3]:
  ['texture', 'burlap']

# access named fields as dict entries, or output as dict
>>> print(result['shape'])
SQUARE
>>> print(result.as_dict())
{'shape': 'SQUARE', 'posn': 'upper left', 'color': 'light blue', 'texture': 'burlap'}

See more examples at ParseResults of accessing fields by results name.

class Each(exprs: Iterable[ParserElement], savelist: bool = True)

Bases: ParseExpression

Requires all given ParserElement s to be found, but in any order. Expressions may be separated by whitespace.

May be constructed using the '&' operator.

Example:

color = one_of("RED ORANGE YELLOW GREEN BLUE PURPLE BLACK WHITE BROWN")
shape_type = one_of("SQUARE CIRCLE TRIANGLE STAR HEXAGON OCTAGON")
integer = Word(nums)
shape_attr = "shape:" + shape_type("shape")
posn_attr = "posn:" + Group(integer("x") + ',' + integer("y"))("posn")
color_attr = "color:" + color("color")
size_attr = "size:" + integer("size")

# use Each (using operator '&') to accept attributes in any order
# (shape and posn are required, color and size are optional)
shape_spec = shape_attr & posn_attr & Opt(color_attr) & Opt(size_attr)

shape_spec.run_tests('''
    shape: SQUARE color: BLACK posn: 100, 120
    shape: CIRCLE size: 50 color: BLUE posn: 50,80
    color:GREEN size:20 shape:TRIANGLE posn:20,40
    '''
    )

prints:

shape: SQUARE color: BLACK posn: 100, 120
['shape:', 'SQUARE', 'color:', 'BLACK', 'posn:', ['100', ',', '120']]
- color: 'BLACK'
- posn: ['100', ',', '120']
  - x: '100'
  - y: '120'
- shape: 'SQUARE'
...

shape: CIRCLE size: 50 color: BLUE posn: 50,80
['shape:', 'CIRCLE', 'size:', '50', 'color:', 'BLUE',
'posn:', ['50', ',', '80']]
- color: 'BLUE'
- posn: ['50', ',', '80']
  - x: '50'
  - y: '80'
- shape: 'CIRCLE'
- size: '50'
...

color:GREEN size:20 shape:TRIANGLE posn:20,40
['color:', 'GREEN', 'size:', '20', 'shape:', 'TRIANGLE',
'posn:', ['20', ',', '40']]
- color: 'GREEN'
- posn: ['20', ',', '40']
  - x: '20'
  - y: '40'
- shape: 'TRIANGLE'
- size: '20'
...

class Empty(match_string: str = '', **kwargs)

Bases: Literal

An empty token, will always match.

class FollowedBy(expr: ParserElement | str)

Bases: ParseElementEnhance

Lookahead matching of the given parse expression. FollowedBy does not advance the parsing position within the input string, it only verifies that the specified parse expression matches at the current position. FollowedBy always returns a null token list. If any results names are defined in the lookahead expression, those will be returned for access by name.

Example:

# use FollowedBy to match a label only if it is followed by a ':'
data_word = Word(alphas)
label = data_word + FollowedBy(':')
attr_expr = Group(
    label + Suppress(':')
    + OneOrMore(data_word, stop_on=label).set_parse_action(' '.join)
)

attr_expr[1, ...].parse_string(
    "shape: SQUARE color: BLACK posn: upper left").pprint()

prints:

[['shape', 'SQUARE'], ['color', 'BLACK'], ['posn', 'upper left']]

class Forward(other: ParserElement | str | None = None)

Bases: ParseElementEnhance

Forward declaration of an expression to be defined later - used for recursive grammars, such as algebraic infix notation. When the expression is known, it is assigned to the Forward instance using the '<<' operator.

Note

Take care when assigning to Forward not to overlook precedence of operators.

Specifically, '|' has a lower precedence than '<<', so that:

fwd_expr << a | b | c

will actually be evaluated as:

(fwd_expr << a) | b | c

thereby leaving b and c out as parseable alternatives. It is recommended that you explicitly group the values inserted into the Forward:

fwd_expr << (a | b | c)

Converting to use the '<<=' operator instead will avoid this problem.

See ParseResults.pprint() for an example of a recursive parser created using Forward.

__lshift__(other) → Forward

__or__(other) → ParserElement

Implementation of | operator - returns MatchFirst

Changed in version 3.1.0: Support expr | "" as a synonym for Optional(expr).

copy() → ParserElement

Returns a copy of this expression.

Generally only used internally by pyparsing.

ignoreWhitespace(recursive: bool = True) → ParserElement

Deprecated since version 3.0.0: Use ignore_whitespace instead

ignore_whitespace(recursive: bool = True) → ParserElement

Extends ignore_whitespace defined in base class.

leaveWhitespace(recursive: bool = True) → ParserElement

Deprecated since version 3.0.0: Use leave_whitespace instead

leave_whitespace(recursive: bool = True) → ParserElement

Extends leave_whitespace defined in base class.

validate(validateTrace=None) → None

Deprecated since version 3.0.0: Do not use to check for left recursion.

Check defined expressions for valid structure, check for infinite recursive definitions.

class GoToColumn(colno: int)

Bases: PositionToken

Token to advance to a specific column of input text; useful for tabular report scraping.

class Group(expr: ParserElement, aslist: bool = False)

Bases: TokenConverter

Converter to return the matched tokens as a list - useful for returning tokens of ZeroOrMore and OneOrMore expressions.

The optional aslist argument when set to True will return the parsed tokens as a Python list instead of a pyparsing ParseResults.

Example:

>>> ident = Word(alphas)
>>> num = Word(nums)
>>> term = ident | num
>>> func = ident + Opt(DelimitedList(term))
>>> print(func.parse_string("fn a, b, 100"))
['fn', 'a', 'b', '100']

>>> func = ident + Group(Opt(DelimitedList(term)))
>>> print(func.parse_string("fn a, b, 100"))
['fn', ['a', 'b', '100']]

class IndentedBlock(expr: ParserElement, *, recursive: bool = False, grouped: bool = True)

Bases: ParseElementEnhance

Expression to match one or more expressions at a given indentation level. Useful for parsing text where structure is implied by indentation (like Python source code).

Example:

'''
BNF:
statement ::= assignment_stmt | if_stmt
assignment_stmt ::= identifier '=' rvalue
rvalue ::= identifier | integer
if_stmt ::= 'if' bool_condition block
block ::= ([indent] statement)...
identifier ::= [A..Za..z]
integer ::= [0..9]...
bool_condition ::= 'TRUE' | 'FALSE'
'''

IF, TRUE, FALSE = Keyword.using_each("IF TRUE FALSE".split())

statement = Forward()
identifier = Char(alphas)
integer = Word(nums).add_parse_action(lambda t: int(t[0]))
rvalue = identifier | integer
assignment_stmt = identifier + "=" + rvalue

if_stmt = IF + (TRUE | FALSE) + IndentedBlock(statement)

statement <<= Group(assignment_stmt | if_stmt)

result = if_stmt.parse_string('''
    IF TRUE
        a = 1000
        b = 2000
        IF FALSE
            z = 100
''')
print(result.dump())

['IF', 'TRUE', [['a', '=', 1000], ['b', '=', 2000], ['IF', 'FALSE', [['z', '=', 100]]]]]
[0]:
  IF
[1]:
  TRUE
[2]:
  [['a', '=', 1000], ['b', '=', 2000], ['IF', 'FALSE', [['z', '=', 100]]]]
  [0]:
    ['a', '=', 1000]
  [1]:
    ['b', '=', 2000]
  [2]:
    ['IF', 'FALSE', [['z', '=', 100]]]
    [0]:
      IF
    [1]:
      FALSE
    [2]:
      [['z', '=', 100]]
      [0]:
        ['z', '=', 100]

class Keyword(match_string: str = '', ident_chars: str | None = None, caseless: bool = False, **kwargs)

Bases: Token

Token to exactly match a specified string as a keyword, that is, it must be immediately preceded and followed by whitespace or non-keyword characters. Compare with Literal:

• Literal("if") will match the leading 'if' in 'ifAndOnlyIf'.

• Keyword("if") will not; it will only match the leading 'if' in 'if x=1', or 'if(y==2)'

Accepts two optional constructor arguments in addition to the keyword string:

• ident_chars is a string of characters that would be valid identifier characters, defaulting to all alphanumerics + “_” and “$”

• caseless allows case-insensitive matching, default is False.

Example:

>>> Keyword("start").parse_string("start")
ParseResults(['start'], {})
>>> Keyword("start").parse_string("starting")
Traceback (most recent call last):
ParseException: Expected Keyword 'start', keyword was immediately
followed by keyword character, found 'ing'  (at char 5), (line:1, col:6)

>>> Keyword("start").parse_string("starting").debug()
Traceback (most recent call last):
ParseException: Expected Keyword "start", keyword was immediately
followed by keyword character, found 'ing' ...

For case-insensitive matching, use CaselessKeyword.

DEFAULT_KEYWORD_CHARS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_$'

property identChars: set[str]

Deprecated since version 3.3.0: use ident_chars instead.

Property returning the characters being used as keyword characters for this expression.

static setDefaultKeywordChars(chars) → None

Deprecated since version 3.0.0: Use set_default_keyword_chars instead

static set_default_keyword_chars(chars) → None

Overrides the default characters used by Keyword expressions.

class LineEnd

Bases: PositionToken

Matches if current position is at the end of a line within the parse string

class LineStart

Bases: PositionToken

Matches if current position is at the logical beginning of a line (after skipping whitespace) within the parse string

Example:

test = '''\
AAA this line
AAA and this line
  AAA and even this line
B AAA but definitely not this line
'''

for t in (LineStart() + 'AAA' + rest_of_line).search_string(test):
    print(t)

prints:

['AAA', ' this line']
['AAA', ' and this line']
['AAA', ' and even this line']

class Literal(match_string: str = '', **kwargs)

Bases: Token

Token to exactly match a specified string.

Example:

>>> Literal('abc').parse_string('abc')
ParseResults(['abc'], {})
>>> Literal('abc').parse_string('abcdef')
ParseResults(['abc'], {})
>>> Literal('abc').parse_string('ab')
Traceback (most recent call last):
ParseException: Expected 'abc', found 'ab'  (at char 0), (line: 1, col: 1)

For case-insensitive matching, use CaselessLiteral.

For keyword matching (force word break before and after the matched string), use Keyword or CaselessKeyword.

class Located(expr: ParserElement | str, savelist: bool = False)

Bases: ParseElementEnhance

Decorates a returned token with its starting and ending locations in the input string.

This helper adds the following results names:

• locn_start - location where matched expression begins

• locn_end - location where matched expression ends

• value - the actual parsed results

Be careful if the input text contains <TAB> characters, you may want to call ParserElement.parse_with_tabs

Example:

wd = Word(alphas)
for match in Located(wd).search_string("ljsdf123lksdjjf123lkkjj1222"):
    print(match)

prints:

[0, ['ljsdf'], 5]
[8, ['lksdjjf'], 15]
[18, ['lkkjj'], 23]

class MatchFirst(exprs: Iterable[ParserElement], savelist: bool = False)

Bases: ParseExpression

Requires that at least one ParserElement is found. If more than one expression matches, the first one listed is the one that will match. May be constructed using the '|' operator.

Example: Construct MatchFirst using ‘|’ operator

# watch the order of expressions to match
>>> number = Word(nums) | Combine(Word(nums) + '.' + Word(nums))
>>> print(number.search_string("123 3.1416 789"))  # Fail!
[['123'], ['3'], ['1416'], ['789']]

# put more selective expression first
>>> number = Combine(Word(nums) + '.' + Word(nums)) | Word(nums)
>>> print(number.search_string("123 3.1416 789"))  # Better
[['123'], ['3.1416'], ['789']]

class NoMatch

Bases: Token

A token that will never match.

class NotAny(expr: ParserElement | str)

Bases: ParseElementEnhance

Lookahead to disallow matching with the given parse expression. NotAny does not advance the parsing position within the input string, it only verifies that the specified parse expression does not match at the current position. Also, NotAny does not skip over leading whitespace. NotAny always returns a null token list. May be constructed using the '~' operator.

Example:

AND, OR, NOT = map(CaselessKeyword, "AND OR NOT".split())

# take care not to mistake keywords for identifiers
ident = ~(AND | OR | NOT) + Word(alphas)
boolean_term = Opt(NOT) + ident

# very crude boolean expression - to support parenthesis groups and
# operation hierarchy, use infix_notation
boolean_expr = boolean_term + ((AND | OR) + boolean_term)[...]

# integers that are followed by "." are actually floats
integer = Word(nums) + ~Char(".")

class OneOrMore(

expr: str | ParserElement,

stop_on: ParserElement | str | None = None,

**kwargs,

)

Bases: _MultipleMatch

Repetition of one or more of the given expression.

Parameters:

• expr - expression that must match one or more times

• stop_on - (default= None) - expression for a terminating sentinel (only required if the sentinel would ordinarily match the repetition expression)

Example:

>>> data_word = Word(alphas)
>>> label = data_word + FollowedBy(':')
>>> attr_expr = Group(
...     label + Suppress(':')
...     + OneOrMore(data_word).set_parse_action(' '.join))

>>> text = "shape: SQUARE posn: upper left color: BLACK"

# Fail! read 'posn' as data instead of next label
>>> attr_expr[1, ...].parse_string(text).pprint()
[['shape', 'SQUARE posn']]

# use stop_on attribute for OneOrMore
# to avoid reading label string as part of the data
>>> attr_expr = Group(
...     label + Suppress(':')
...     + OneOrMore(
...         data_word, stop_on=label).set_parse_action(' '.join))
>>> OneOrMore(attr_expr).parse_string(text).pprint()  # Better
[['shape', 'SQUARE'], ['posn', 'upper left'], ['color', 'BLACK']]

# could also be written as
>>> (attr_expr * (1,)).parse_string(text).pprint()
[['shape', 'SQUARE'], ['posn', 'upper left'], ['color', 'BLACK']]

class OnlyOnce(method_call: Callable[[str, int, ParseResults], Any])

Bases: object

Wrapper for parse actions, to ensure they are only called once. Note: parse action signature must include all 3 arguments.

__call__(

s: str,

l: int,

t: ParseResults,

) → ParseResults

Call self as a function.

reset()

Allow the associated parse action to be called once more.

class OpAssoc(*values)

Bases: Enum

Enumeration of operator associativity - used in constructing InfixNotationOperatorSpec for infix_notation

LEFT = 1

RIGHT = 2

class Opt(expr: ParserElement | str, default: Any = __optionalNotMatched)

Bases: ParseElementEnhance

Optional matching of the given expression.

Parameters:

• expr – expression that must match zero or more times

• default – (optional) - value to be returned if the optional expression is not found.

Example:

# US postal code can be a 5-digit zip, plus optional 4-digit qualifier
zip = Combine(Word(nums, exact=5) + Opt('-' + Word(nums, exact=4)))
zip.run_tests('''
    # traditional ZIP code
    12345

    # ZIP+4 form
    12101-0001

    # invalid ZIP
    98765-
    ''')

prints:

 # traditional ZIP code
 12345
 ['12345']

 # ZIP+4 form
 12101-0001
 ['12101-0001']

 # invalid ZIP
 98765-
 98765-
      ^
 ParseException: Expected end of text, found '-' (at char 5), (line:1, col:6)
 FAIL: Expected end of text, found '-'  (at char 5), (line:1, col:6)

Optional

alias of Opt

class Or(exprs: Iterable[ParserElement], savelist: bool = False)

Bases: ParseExpression

Requires that at least one ParserElement is found. If two expressions match, the expression that matches the longest string will be used. May be constructed using the '^' operator.

Example:

# construct Or using '^' operator

number = Word(nums) ^ Combine(Word(nums) + '.' + Word(nums))
print(number.search_string("123 3.1416 789"))

prints:

[['123'], ['3.1416'], ['789']]

exception ParseBaseException(pstr: str, loc: int = 0, msg: str | None = None, elem=None)

Bases: Exception

base exception class for all parsing runtime exceptions

__str__() → str

Changed in version 3.2.0: Now uses formatted_message() to format message.

args: tuple[str, int, str | None]

property col: int

Return the 1-based column on the line of text where the exception occurred.

property column: int

Return the 1-based column on the line of text where the exception occurred.

copy()

explain(depth: int = 16) → str

Method to translate the Python internal traceback into a list of the pyparsing expressions that caused the exception to be raised.

Parameters:

• depth (default=16) - number of levels back in the stack trace to list expression and function names; if None, the full stack trace names will be listed; if 0, only the failing input line, marker, and exception string will be shown

Returns a multi-line string listing the ParserElements and/or function names in the exception’s stack trace.

Example:

# an expression to parse 3 integers
expr = pp.Word(pp.nums) * 3
try:
    # a failing parse - the third integer is prefixed with "A"
    expr.parse_string("123 456 A789")
except pp.ParseException as pe:
    print(pe.explain(depth=0))

prints:

123 456 A789
        ^
ParseException: Expected W:(0-9), found 'A789'  (at char 8), (line:1, col:9)

Note: the diagnostic output will include string representations of the expressions that failed to parse. These representations will be more helpful if you use set_name to give identifiable names to your expressions. Otherwise they will use the default string forms, which may be cryptic to read.

Note: pyparsing’s default truncation of exception tracebacks may also truncate the stack of expressions that are displayed in the explain output. To get the full listing of parser expressions, you may have to set ParserElement.verbose_stacktrace = True

static explain_exception(exc: Exception, depth: int = 16) → str

Method to take an exception and translate the Python internal traceback into a list of the pyparsing expressions that caused the exception to be raised.

Parameters:

• exc - exception raised during parsing (need not be a ParseException, in support of Python exceptions that might be raised in a parse action)

• depth (default=16) - number of levels back in the stack trace to list expression and function names; if None, the full stack trace names will be listed; if 0, only the failing input line, marker, and exception string will be shown

Returns a multi-line string listing the ParserElements and/or function names in the exception’s stack trace.

formatted_message() → str

Output the formatted exception message. Can be overridden to customize the message formatting or contents.

Added in version 3.2.0.

property found: str

property line: str

Return the line of text where the exception occurred.

property lineno: int

Return the 1-based line number of text where the exception occurred.

loc: int

markInputline(marker_string: str | None = None, **kwargs) → str

Deprecated since version 3.0.0: Use mark_input_line instead

mark_input_line(marker_string: str | None = None, **kwargs) → str

Extracts the exception line from the input string, and marks the location of the exception with a special symbol.

msg: str

property parserElement

parser_element: Any

pstr: str

class ParseElementEnhance(expr: ParserElement | str, savelist: bool = False)

Bases: ParserElement

Abstract subclass of ParserElement, for combining and post-processing parsed tokens.

ignore(other) → ParserElement

Define expression to be ignored (e.g., comments) while doing pattern matching; may be called repeatedly, to define multiple comment or other ignorable patterns.

ignoreWhitespace(recursive: bool = True) → ParserElement

Deprecated since version 3.0.0: Use ignore_whitespace instead

ignore_whitespace(recursive: bool = True) → ParserElement

Extends ignore_whitespace defined in base class, and also invokes ignore_whitespace on

the contained expression.

leaveWhitespace(recursive: bool = True) → ParserElement

Deprecated since version 3.0.0: Use leave_whitespace instead

leave_whitespace(recursive: bool = True) → ParserElement

Extends leave_whitespace defined in base class, and also invokes leave_whitespace on

the contained expression.

validate(validateTrace=None) → None

Deprecated since version 3.0.0: Do not use to check for left recursion.

Check defined expressions for valid structure, check for infinite recursive definitions.

exception ParseException(pstr: str, loc: int = 0, msg: str | None = None, elem=None)

Bases: ParseBaseException

Exception thrown when a parse expression doesn’t match the input string

Example:

integer = Word(nums).set_name("integer")
try:
    integer.parse_string("ABC")
except ParseException as pe:
    print(pe, f"column: {pe.column}")

prints:

Expected integer, found 'ABC'  (at char 0), (line:1, col:1) column: 1

args: tuple[str, int, str | None]

loc: int

msg: str

parser_element: Any

pstr: str

class ParseExpression(exprs: Iterable[ParserElement], savelist: bool = False)

Bases: ParserElement

Abstract subclass of ParserElement, for combining and post-processing parsed tokens.

append(other) → ParserElement

Add an expression to the list of expressions related to this ParseExpression instance.

copy() → ParserElement

Returns a copy of this expression.

Generally only used internally by pyparsing.

ignore(other) → ParserElement

Define expression to be ignored (e.g., comments) while doing pattern matching; may be called repeatedly, to define multiple comment or other ignorable patterns.

ignoreWhitespace(recursive: bool = True) → ParserElement

Deprecated since version 3.0.0: Use ignore_whitespace instead

ignore_whitespace(recursive: bool = True) → ParserElement

Extends ignore_whitespace defined in base class, and also invokes ignore_whitespace on

all contained expressions.

leaveWhitespace(recursive: bool = True) → ParserElement

Deprecated since version 3.0.0: Use leave_whitespace instead

leave_whitespace(recursive: bool = True) → ParserElement

Extends leave_whitespace defined in base class, and also invokes leave_whitespace on

all contained expressions.

validate(validateTrace=None) → None

Deprecated since version 3.0.0: Do not use to check for left recursion.

Check defined expressions for valid structure, check for infinite recursive definitions.

exception ParseFatalException(pstr: str, loc: int = 0, msg: str | None = None, elem=None)

Bases: ParseBaseException

User-throwable exception thrown when inconsistent parse content is found; stops all parsing immediately

args: tuple[str, int, str | None]

loc: int

msg: str

parser_element: Any

pstr: str

class ParseResults(toklist=None, name=None, **kwargs)

Bases: object

Structured parse results, to provide multiple means of access to the parsed data:

• as a list (len(results))

• by list index (results[0], results[1], etc.)

• by attribute (results.<results_name> - see ParserElement.set_results_name)

Example:

integer = Word(nums)
date_str = (integer.set_results_name("year") + '/'
            + integer.set_results_name("month") + '/'
            + integer.set_results_name("day"))
# equivalent form:
# date_str = (integer("year") + '/'
#             + integer("month") + '/'
#             + integer("day"))

# parse_string returns a ParseResults object
result = date_str.parse_string("1999/12/31")

def test(s, fn=repr):
    print(f"{s} -> {fn(eval(s))}")

test("list(result)")
test("result[0]")
test("result['month']")
test("result.day")
test("'month' in result")
test("'minutes' in result")
test("result.dump()", str)

prints:

list(result) -> ['1999', '/', '12', '/', '31']
result[0] -> '1999'
result['month'] -> '12'
result.day -> '31'
'month' in result -> True
'minutes' in result -> False
result.dump() -> ['1999', '/', '12', '/', '31']
- day: '31'
- month: '12'
- year: '1999'

class List(contained=None)

Bases: list

Simple wrapper class to distinguish parsed list results that should be preserved as actual Python lists, instead of being converted to ParseResults:

import pyparsing as pp
ppc = pp.common

LBRACK, RBRACK, LPAR, RPAR = pp.Suppress.using_each("[]()")
element = pp.Forward()
item = ppc.integer
item_list = pp.DelimitedList(element)
element_list = LBRACK + item_list + RBRACK | LPAR + item_list + RPAR
element <<= item | element_list

# add parse action to convert from ParseResults
# to actual Python collection types
@element_list.add_parse_action
def as_python_list(t):
    return pp.ParseResults.List(t.as_list())

element.run_tests('''
    100
    [2,3,4]
    [[2, 1],3,4]
    [(2, 1),3,4]
    (2,3,4)
    ([2, 3], 4)
    ''', post_parse=lambda s, r: (r[0], type(r[0]))
)

prints:

100
(100, <class 'int'>)

[2,3,4]
([2, 3, 4], <class 'list'>)

[[2, 1],3,4]
([[2, 1], 3, 4], <class 'list'>)

[(2, 1),3,4]
([[2, 1], 3, 4], <class 'list'>)

(2,3,4)
([2, 3, 4], <class 'list'>)

([2, 3], 4)
([[2, 3], 4], <class 'list'>)

(Used internally by Group when aslist=True.)

__add__(other: ParseResults) → ParseResults

__getitem__(i)

__str__() → str

Return str(self).

append(item)

Add single element to end of ParseResults list of elements.

Example:

>>> numlist = Word(nums)[...]
>>> print(numlist.parse_string("0 123 321"))
['0', '123', '321']

>>> # use a parse action to compute the sum of the parsed integers,
>>> # and add it to the end
>>> def append_sum(tokens):
...     tokens.append(sum(map(int, tokens)))
...
>>> numlist.add_parse_action(append_sum)
[W:(0-9)]...
>>> print(numlist.parse_string("0 123 321"))
['0', '123', '321', 444]

asDict() → dict

Returns the named parse results as a nested dictionary.

Example:

>>> integer = pp.Word(pp.nums)
>>> date_str = integer("year") + '/' + integer("month") + '/' + integer("day")

>>> result = date_str.parse_string('1999/12/31')
>>> type(result)
<class 'pyparsing.results.ParseResults'>
>>> result
ParseResults(['1999', '/', '12', '/', '31'], {'year': '1999', 'month': '12', 'day': '31'})

>>> result_dict = result.as_dict()
>>> type(result_dict)
<class 'dict'>
>>> result_dict
{'year': '1999', 'month': '12', 'day': '31'}

>>> # even though a ParseResults supports dict-like access,
>>> # sometime you just need to have a dict
>>> import json
>>> print(json.dumps(result))
Traceback (most recent call last):
TypeError: Object of type ParseResults is not JSON serializable
>>> print(json.dumps(result.as_dict()))
{"year": "1999", "month": "12", "day": "31"}

asList(*, flatten: bool = False) → list

Returns the parse results as a nested list of matching tokens, all converted to strings. If flatten is True, all the nesting levels in the returned list are collapsed.

Example:

>>> patt = Word(alphas)[1, ...]
>>> result = patt.parse_string("sldkj lsdkj sldkj")
>>> # even though the result prints in string-like form,
>>> # it is actually a pyparsing ParseResults
>>> type(result)
<class 'pyparsing.results.ParseResults'>
>>> print(result)
['sldkj', 'lsdkj', 'sldkj']

>>> # Use as_list() to create an actual list
>>> result_list = result.as_list()
>>> type(result_list)
<class 'list'>
>>> print(result_list)
['sldkj', 'lsdkj', 'sldkj']

Changed in version 3.2.0: New flatten argument.

as_dict() → dict

Returns the named parse results as a nested dictionary.

Example:

>>> integer = pp.Word(pp.nums)
>>> date_str = integer("year") + '/' + integer("month") + '/' + integer("day")

>>> result = date_str.parse_string('1999/12/31')
>>> type(result)
<class 'pyparsing.results.ParseResults'>
>>> result
ParseResults(['1999', '/', '12', '/', '31'], {'year': '1999', 'month': '12', 'day': '31'})

>>> result_dict = result.as_dict()
>>> type(result_dict)
<class 'dict'>
>>> result_dict
{'year': '1999', 'month': '12', 'day': '31'}

>>> # even though a ParseResults supports dict-like access,
>>> # sometime you just need to have a dict
>>> import json
>>> print(json.dumps(result))
Traceback (most recent call last):
TypeError: Object of type ParseResults is not JSON serializable
>>> print(json.dumps(result.as_dict()))
{"year": "1999", "month": "12", "day": "31"}

as_list(*, flatten: bool = False) → list

Returns the parse results as a nested list of matching tokens, all converted to strings. If flatten is True, all the nesting levels in the returned list are collapsed.

Example:

>>> patt = Word(alphas)[1, ...]
>>> result = patt.parse_string("sldkj lsdkj sldkj")
>>> # even though the result prints in string-like form,
>>> # it is actually a pyparsing ParseResults
>>> type(result)
<class 'pyparsing.results.ParseResults'>
>>> print(result)
['sldkj', 'lsdkj', 'sldkj']

>>> # Use as_list() to create an actual list
>>> result_list = result.as_list()
>>> type(result_list)
<class 'list'>
>>> print(result_list)
['sldkj', 'lsdkj', 'sldkj']

Changed in version 3.2.0: New flatten argument.

clear()

Clear all elements and results names.

copy() → ParseResults

Returns a new shallow copy of a ParseResults object. ParseResults items contained within the source are shared with the copy. Use ParseResults.deepcopy() to create a copy with its own separate content values.

deepcopy() → ParseResults

Returns a new deep copy of a ParseResults object.

Added in version 3.1.0.

dump(indent='', full=True, include_list=True, _depth=0) → str

Diagnostic method for listing out the contents of a ParseResults. Accepts an optional indent argument so that this string can be embedded in a nested display of other data.

Example:

integer = Word(nums)
date_str = integer("year") + '/' + integer("month") + '/' + integer("day")

result = date_str.parse_string('1999/12/31')
print(result.dump())

prints:

['1999', '/', '12', '/', '31']
- day: '31'
- month: '12'
- year: '1999'

extend(itemseq)

Add sequence of elements to end of ParseResults list of elements.

Example:

patt = Word(alphas)[1, ...]

# use a parse action to append the reverse of the matched strings,
# to make a palindrome
def make_palindrome(tokens):
    tokens.extend(reversed([t[::-1] for t in tokens]))
    return ''.join(tokens)

patt.add_parse_action(make_palindrome)
print(patt.parse_string("lskdj sdlkjf lksd"))

prints:

['lskdjsdlkjflksddsklfjkldsjdksl']

classmethod from_dict(other, name=None) → ParseResults

Helper classmethod to construct a ParseResults from a dict, preserving the name-value relations as results names. If an optional name argument is given, a nested ParseResults will be returned.

get(key, default_value=None)

Returns named result matching the given key, or if there is no such name, then returns the given default_value or None if no default_value is specified.

Similar to dict.get().

Example:

>>> integer = Word(nums)
>>> date_str = integer("year") + '/' + integer("month") + '/' + integer("day")

>>> result = date_str.parse_string("1999/12/31")
>>> result.get("year")
'1999'
>>> result.get("hour", "not specified")
'not specified'
>>> result.get("hour")

getName() → str | None

Returns the results name for this token expression.

Useful when several different expressions might match at a particular location.

Example:

integer = Word(nums)
ssn_expr = Regex(r"\d\d\d-\d\d-\d\d\d\d")
house_number_expr = Suppress('#') + Word(nums, alphanums)
user_data = (Group(house_number_expr)("house_number")
            | Group(ssn_expr)("ssn")
            | Group(integer)("age"))
user_info = user_data[1, ...]

result = user_info.parse_string("22 111-22-3333 #221B")
for item in result:
    print(item.get_name(), ':', item[0])

prints:

age : 22
ssn : 111-22-3333
house_number : 221B

get_name() → str | None

Returns the results name for this token expression.

Useful when several different expressions might match at a particular location.

Example:

integer = Word(nums)
ssn_expr = Regex(r"\d\d\d-\d\d-\d\d\d\d")
house_number_expr = Suppress('#') + Word(nums, alphanums)
user_data = (Group(house_number_expr)("house_number")
            | Group(ssn_expr)("ssn")
            | Group(integer)("age"))
user_info = user_data[1, ...]

result = user_info.parse_string("22 111-22-3333 #221B")
for item in result:
    print(item.get_name(), ':', item[0])

prints:

age : 22
ssn : 111-22-3333
house_number : 221B

haskeys() → bool

Since keys() returns an iterator, this method is helpful in bypassing code that looks for the existence of any defined results names.

insert(index, ins_string)

Inserts new element at location index in the list of parsed tokens.

Similar to list.insert().

Example:

>>> numlist = Word(nums)[...]
>>> print(numlist.parse_string("0 123 321"))
['0', '123', '321']

>>> # use a parse action to insert the parse location
>>> # in the front of the parsed results
>>> def insert_locn(locn, tokens):
...     tokens.insert(0, locn)
...
>>> numlist.add_parse_action(insert_locn)
[W:(0-9)]...
>>> print(numlist.parse_string("0 123 321"))
[0, '0', '123', '321']

items()

keys()

pop(*args, **kwargs)

Removes and returns item at specified index (default= last). Supports both list and dict semantics for pop(). If passed no argument or an integer argument, it will use list semantics and pop tokens from the list of parsed tokens. If passed a non-integer argument (most likely a string), it will use dict semantics and pop the corresponding value from any defined results names. A second default return value argument is supported, just as in dict.pop().

Example:

>>> numlist = Word(nums)[...]
>>> print(numlist.parse_string("0 123 321"))
['0', '123', '321']

>>> def remove_first(tokens):
...     tokens.pop(0)
...
>>> numlist.add_parse_action(remove_first)
[W:(0-9)]...
>>> print(numlist.parse_string("0 123 321"))
['123', '321']

>>> label = Word(alphas)
>>> patt = label("LABEL") + Word(nums)[1, ...]
>>> print(patt.parse_string("AAB 123 321").dump())
['AAB', '123', '321']
- LABEL: 'AAB'

>>> # Use pop() in a parse action to remove named result
>>> # (note that corresponding value is not
>>> # removed from list form of results)
>>> def remove_LABEL(tokens):
...     tokens.pop("LABEL")
...     return tokens
...
>>> patt.add_parse_action(remove_LABEL)
{W:(A-Za-z) {W:(0-9)}...}
>>> print(patt.parse_string("AAB 123 321").dump())
['AAB', '123', '321']

pprint(*args, **kwargs)

Pretty-printer for parsed results as a list, using the pprint module. Accepts additional positional or keyword args as defined for pprint.pprint .

Example:

ident = Word(alphas, alphanums)
num = Word(nums)
func = Forward()
term = ident | num | Group('(' + func + ')')
func <<= ident + Group(Optional(DelimitedList(term)))
result = func.parse_string("fna a,b,(fnb c,d,200),100")
result.pprint(width=40)

prints:

['fna',
 ['a',
  'b',
  ['(', 'fnb', ['c', 'd', '200'], ')'],
  '100']]

values()

exception ParseSyntaxException(pstr: str, loc: int = 0, msg: str | None = None, elem=None)

Bases: ParseFatalException

Just like ParseFatalException, but thrown internally when an ErrorStop (‘-’ operator) indicates that parsing is to stop immediately because an unbacktrackable syntax error has been found.

args: tuple[str, int, str | None]

loc: int

msg: str

parser_element: Any

pstr: str

class ParserElement(savelist: bool = False)

Bases: ABC

Abstract base level parser element class.

DEFAULT_WHITE_CHARS: str = ' \n\t\r'

class DebugActions(debug_try, debug_match, debug_fail)

Bases: NamedTuple

debug_fail: Callable[[str, int, ParserElement, Exception, bool], None] | None

Alias for field number 2

debug_match: Callable[[str, int, int, ParserElement, ParseResults, bool], None] | None

Alias for field number 1

debug_try: Callable[[str, int, ParserElement, bool], None] | None

Alias for field number 0

class NullCache

Bases: dict

A null cache type for initialization of the packrat_cache class variable. If/when enable_packrat() is called, this null cache will be replaced by a proper _CacheType class instance.

clear() → None

Remove all items from the dict.

get(*args) → Any

Return the value for key if key is in the dictionary, else default.

not_in_cache: bool = True

set(*args) → None

__add__(other) → ParserElement

Implementation of + operator - returns And. Adding strings to a ParserElement converts them to Literals by default.

Example:

greet = Word(alphas) + "," + Word(alphas) + "!"
hello = "Hello, World!"
print(hello, "->", greet.parse_string(hello))

prints:

Hello, World! -> ['Hello', ',', 'World', '!']

... may be used as a parse expression as a short form of SkipTo:

Literal('start') + ... + Literal('end')

is equivalent to:

Literal('start') + SkipTo('end')("_skipped*") + Literal('end')

Note that the skipped text is returned with ‘_skipped’ as a results name, and to support having multiple skips in the same parser, the value returned is a list of all skipped text.

__and__(other) → ParserElement

Implementation of & operator - returns Each

__call__(name: str | None = None) → ParserElement

Shortcut for set_results_name, with list_all_matches=False.

If name is given with a trailing '*' character, then list_all_matches will be passed as True.

If name is omitted, same as calling copy.

Example:

# these are equivalent
userdata = (
    Word(alphas).set_results_name("name")
    + Word(nums + "-").set_results_name("socsecno")
)

userdata = Word(alphas)("name") + Word(nums + "-")("socsecno")

__getitem__(key)

use [] indexing notation as a short form for expression repetition:

• expr[n] is equivalent to expr*n

• expr[m, n] is equivalent to expr*(m, n)

• expr[n, ...] or expr[n,] is equivalent

  to expr*n + ZeroOrMore(expr) (read as “at least n instances of expr”)

• expr[..., n] is equivalent to expr*(0, n)

  (read as “0 to n instances of expr”)

• expr[...] and expr[0, ...] are equivalent to ZeroOrMore(expr)

• expr[1, ...] is equivalent to OneOrMore(expr)

None may be used in place of ....

Note that expr[..., n] and expr[m, n] do not raise an exception if more than n exprs exist in the input stream. If this behavior is desired, then write expr[..., n] + ~expr.

For repetition with a stop_on expression, use slice notation:

• expr[...: end_expr] and expr[0, ...: end_expr] are equivalent to ZeroOrMore(expr, stop_on=end_expr)

• expr[1, ...: end_expr] is equivalent to OneOrMore(expr, stop_on=end_expr)

Changed in version 3.1.0: Support for slice notation.

__invert__() → ParserElement

Implementation of ~ operator - returns NotAny

__mul__(other) → ParserElement

Implementation of * operator, allows use of expr * 3 in place of expr + expr + expr. Expressions may also be multiplied by a 2-integer tuple, similar to {min, max} multipliers in regular expressions. Tuples may also include None as in:

• expr*(n, None) or expr*(n, ) is equivalent to expr*n + ZeroOrMore(expr) (read as “at least n instances of expr”)

• expr*(None, n) is equivalent to expr*(0, n) (read as “0 to n instances of expr”)

• expr*(None, None) is equivalent to ZeroOrMore(expr)

• expr*(1, None) is equivalent to OneOrMore(expr)

Note that expr*(None, n) does not raise an exception if more than n exprs exist in the input stream; that is, expr*(None, n) does not enforce a maximum number of expr occurrences. If this behavior is desired, then write expr*(None, n) + ~expr

__or__(other) → ParserElement

Implementation of | operator - returns MatchFirst

Changed in version 3.1.0: Support expr | "" as a synonym for Optional(expr).

__str__() → str

Return str(self).

__sub__(other) → ParserElement

Implementation of - operator, returns And with error stop

__xor__(other) → ParserElement

Implementation of ^ operator - returns Or

addCondition(

*fns: Callable[[], bool] | Callable[[ParseResults], bool] | Callable[[int, ParseResults], bool] | Callable[[str, int, ParseResults], bool],

call_during_try: bool = False,

**kwargs: Any,

) → ParserElement

Deprecated since version 3.0.0: Use add_condition instead

addParseAction(

*fns: Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any],

call_during_try: bool = False,

**kwargs: Any,

) → ParserElement

Deprecated since version 3.0.0: Use add_parse_action instead

add_condition(

*fns: Callable[[], bool] | Callable[[ParseResults], bool] | Callable[[int, ParseResults], bool] | Callable[[str, int, ParseResults], bool],

call_during_try: bool = False,

**kwargs: Any,

) → ParserElement

Add a boolean predicate function to expression’s list of parse actions. See set_parse_action for function call signatures. Unlike set_parse_action, functions passed to add_condition need to return boolean success/fail of the condition.

Optional keyword arguments:

• message = define a custom message to be used in the raised exception

• fatal = if True, will raise ParseFatalException to stop parsing immediately; otherwise will raise ParseException

• call_during_try = boolean to indicate if this method should be called during internal tryParse calls, default=False

Example:

>>> integer = Word(nums).set_parse_action(lambda toks: int(toks[0]))
>>> year_int = integer.copy().add_condition(
...     lambda toks: toks[0] >= 2000,
...     message="Only support years 2000 and later")
>>> date_str = year_int + '/' + integer + '/' + integer

>>> result = date_str.parse_string("1999/12/31")
Traceback (most recent call last):
ParseException: Only support years 2000 and later...

add_parse_action(

*fns: Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any],

call_during_try: bool = False,

**kwargs: Any,

) → ParserElement

Add one or more parse actions to expression’s list of parse actions. See set_parse_action.

See examples in copy.

canParseNext(instring: str, loc: int, do_actions: bool = False) → bool

Deprecated since version 3.0.0: Use can_parse_next instead

copy() → ParserElement

Make a copy of this ParserElement. Useful for defining different parse actions for the same parsing pattern, using copies of the original parse element.

Example:

integer = Word(nums).set_parse_action(
    lambda toks: int(toks[0]))
integerK = integer.copy().add_parse_action(
    lambda toks: toks[0] * 1024) + Suppress("K")
integerM = integer.copy().add_parse_action(
    lambda toks: toks[0] * 1024 * 1024) + Suppress("M")

print(
    (integerK | integerM | integer)[1, ...].parse_string(
    "5K 100 640K 256M")
)

prints:

[5120, 100, 655360, 268435456]

Equivalent form of expr.copy() is just expr():

integerM = integer().add_parse_action(
    lambda toks: toks[0] * 1024 * 1024) + Suppress("M")

create_diagram(

output_html: TextIO | Path | str,

vertical: int = 3,

show_results_names: bool = False,

show_groups: bool = False,

embed: bool = False,

show_hidden: bool = False,

**kwargs,

) → None

Create a railroad diagram for the parser.

Parameters:

• output_html (str or file-like object) - output target for generated diagram HTML

• vertical (int) - threshold for formatting multiple alternatives vertically instead of horizontally (default=3)

• show_results_names - bool flag whether diagram should show annotations for defined results names

• show_groups - bool flag whether groups should be highlighted with an unlabeled surrounding box

• show_hidden - bool flag to show diagram elements for internal elements that are usually hidden

• embed - bool flag whether generated HTML should omit <HEAD>, <BODY>, and <DOCTYPE> tags to embed the resulting HTML in an enclosing HTML source

• head - str containing additional HTML to insert into the <HEAD> section of the generated code; can be used to insert custom CSS styling

• body - str containing additional HTML to insert at the beginning of the <BODY> section of the generated code

Additional diagram-formatting keyword arguments can also be included; see railroad.Diagram class.

Changed in version 3.1.0: embed argument added.

property defaultName: str

static disableMemoization() → None

Deprecated since version 3.0.0: Use disable_memoization instead

static disable_memoization() → None

Disables active Packrat or Left Recursion parsing and their memoization

This method also works if neither Packrat nor Left Recursion are enabled. This makes it safe to call before activating Packrat nor Left Recursion to clear any previous settings.

static enableLeftRecursion(cache_size_limit: int | None = None, *, force=False) → None

Deprecated since version 3.0.0: Use enable_left_recursion instead

static enablePackrat(cache_size_limit: int | None = 128, *, force: bool = False) → None

Deprecated since version 3.0.0: Use enable_packrat instead

static enable_left_recursion(cache_size_limit: int | None = None, *, force=False) → None

Enables “bounded recursion” parsing, which allows for both direct and indirect left-recursion. During parsing, left-recursive Forward elements are repeatedly matched with a fixed recursion depth that is gradually increased until finding the longest match.

Example:

import pyparsing as pp
pp.ParserElement.enable_left_recursion()

E = pp.Forward("E")
num = pp.Word(pp.nums)

# match `num`, or `num '+' num`, or `num '+' num '+' num`, ...
E <<= E + '+' - num | num

print(E.parse_string("1+2+3+4"))

prints:

['1', '+', '2', '+', '3', '+', '4']

Recursion search naturally memoizes matches of Forward elements and may thus skip reevaluation of parse actions during backtracking. This may break programs with parse actions which rely on strict ordering of side-effects.

Parameters:

• cache_size_limit - (default=``None``) - memoize at most this many Forward elements during matching; if None (the default), memoize all Forward elements.

Bounded Recursion parsing works similar but not identical to Packrat parsing, thus the two cannot be used together. Use force=True to disable any previous, conflicting settings.

static enable_packrat(cache_size_limit: int | None = 128, *, force: bool = False) → None

Enables “packrat” parsing, which adds memoizing to the parsing logic. Repeated parse attempts at the same string location (which happens often in many complex grammars) can immediately return a cached value, instead of re-executing parsing/validating code. Memoizing is done of both valid results and parsing exceptions.

Parameters:

• cache_size_limit - (default= 128) - if an integer value is provided will limit the size of the packrat cache; if None is passed, then the cache size will be unbounded; if 0 is passed, the cache will be effectively disabled.

This speedup may break existing programs that use parse actions that have side-effects. For this reason, packrat parsing is disabled when you first import pyparsing. To activate the packrat feature, your program must call the class method ParserElement.enable_packrat. For best results, call enable_packrat() immediately after importing pyparsing.

Example:

import pyparsing
pyparsing.ParserElement.enable_packrat()

Packrat parsing works similar but not identical to Bounded Recursion parsing, thus the two cannot be used together. Use force=True to disable any previous, conflicting settings.

ignore(other: ParserElement) → ParserElement

Define expression to be ignored (e.g., comments) while doing pattern matching; may be called repeatedly, to define multiple comment or other ignorable patterns.

Example:

>>> patt = Word(alphas)[...]
>>> print(patt.parse_string('ablaj /* comment */ lskjd'))
['ablaj']

>>> patt = Word(alphas)[...].ignore(c_style_comment)
>>> print(patt.parse_string('ablaj /* comment */ lskjd'))
['ablaj', 'lskjd']

ignoreWhitespace(recursive: bool = True) → ParserElement

Deprecated since version 3.0.0: Use ignore_whitespace instead

ignore_whitespace(recursive: bool = True) → ParserElement

Enables the skipping of whitespace before matching the characters in the ParserElement’s defined pattern.

Parameters:

recursive – If True (the default), also enable whitespace skipping in child elements (if any)

static inlineLiteralsUsing(cls: type) → None

Deprecated since version 3.0.0: Use inline_literals_using instead

static inline_literals_using(cls: type) → None

Set class to be used for inclusion of string literals into a parser.

Example:

# default literal class used is Literal
>>> integer = Word(nums)
>>> date_str = (
...     integer("year") + '/'
...     + integer("month") + '/'
...     + integer("day")
... )

>>> date_str.parse_string("1999/12/31")
ParseResults(['1999', '/', '12', '/', '31'],
{'year': '1999', 'month': '12', 'day': '31'})

# change to Suppress
>>> ParserElement.inline_literals_using(Suppress)
>>> date_str = (
...     integer("year") + '/'
...     + integer("month") + '/'
...     + integer("day")
... )

>>> date_str.parse_string("1999/12/31")
ParseResults(['1999', '12', '31'],
{'year': '1999', 'month': '12', 'day': '31'})

# Reset
>>> ParserElement.inline_literals_using(Literal)

leaveWhitespace(recursive: bool = True) → ParserElement

Deprecated since version 3.0.0: Use leave_whitespace instead

leave_whitespace(recursive: bool = True) → ParserElement

Disables the skipping of whitespace before matching the characters in the ParserElement’s defined pattern. This is normally only used internally by the pyparsing module, but may be needed in some whitespace-sensitive grammars.

Parameters:

recursive – If true (the default), also disable whitespace skipping in child elements (if any)

matches(test_string: str, parse_all: bool = True, **kwargs) → bool

Method for quick testing of a parser against a test string. Good for simple inline microtests of sub expressions while building up larger parser.

Parameters:

• test_string – to test against this expression for a match

• parse_all – flag to pass to parse_string() when running tests

Example:

>>> expr = Word(nums)
>>> expr.matches("100")
True

property name: str

Returns a user-defined name if available, but otherwise defaults back to the auto-generated name

packrat_cache: _CacheType = {}

packrat_cache_lock = <unlocked _thread.RLock object owner=0 count=0>

packrat_cache_stats = [0, 0]

parseFile(

file_or_filename: str | Path | TextIO,

encoding: str = 'utf-8',

parse_all: bool = False,

**kwargs,

) → ParseResults

Deprecated since version 3.0.0: Use parse_file instead

parseString(

instring: str,

parse_all: bool = False,

**kwargs,

) → ParseResults

Deprecated since version 3.0.0: Use parse_string instead

parseWithTabs() → ParserElement

Deprecated since version 3.0.0: Use parse_with_tabs instead

parse_file(

file_or_filename: str | Path | TextIO,

encoding: str = 'utf-8',

parse_all: bool = False,

**kwargs,

) → ParseResults

Execute the parse expression on the given file or filename. If a filename is specified (instead of a file object), the entire file is opened, read, and closed before parsing.

parse_string(

instring: str,

parse_all: bool = False,

**kwargs,

) → ParseResults

Parse a string with respect to the parser definition. This function is intended as the primary interface to the client code.

Parameters:

• instring – The input string to be parsed.

• parse_all – If set, the entire input string must match the grammar.

• parseAll – retained for pre-PEP8 compatibility, will be removed in a future release.

Raises:

ParseException – Raised if parse_all is set and the input string does not match the whole grammar.

Returns:

the parsed data as a ParseResults object, which may be accessed as a list, a dict, or an object with attributes if the given parser includes results names.

If the input string is required to match the entire grammar, parse_all flag must be set to True. This is also equivalent to ending the grammar with StringEnd().

To report proper column numbers, parse_string operates on a copy of the input string where all tabs are converted to spaces (8 spaces per tab, as per the default in string.expandtabs). If the input string contains tabs and the grammar uses parse actions that use the loc argument to index into the string being parsed, one can ensure a consistent view of the input string by doing one of the following:

• calling parse_with_tabs on your grammar before calling parse_string (see parse_with_tabs),

• define your parse action using the full (s,loc,toks) signature, and reference the input string using the parse action’s s argument, or

• explicitly expand the tabs in your input string before calling parse_string.

Examples:

By default, partial matches are OK.

>>> res = Word('a').parse_string('aaaaabaaa')
>>> print(res)
['aaaaa']

The parsing behavior varies by the inheriting class of this abstract class. Please refer to the children directly to see more examples.

It raises an exception if parse_all flag is set and instring does not match the whole grammar.

>>> res = Word('a').parse_string('aaaaabaaa', parse_all=True)
Traceback (most recent call last):
ParseException: Expected end of text, found 'b' ...

parse_with_tabs() → ParserElement

Overrides default behavior to expand <TAB> s to spaces before parsing the input string. Must be called before parse_string when the input grammar contains elements that match <TAB> characters.

recursion_lock = <unlocked _thread.RLock object owner=0 count=0>

recursion_memos: collections.abc.MutableMapping[tuple[int, Forward, bool], tuple[int, ParseResults | Exception]] = {}

static resetCache() → None

Deprecated since version 3.0.0: Use reset_cache instead

static reset_cache() → None

Clears caches used by packrat and left-recursion.

runTests(

tests: str | list[str],

parse_all: bool = True,

comment: ParserElement | str | None = '#',

full_dump: bool = True,

print_results: bool = True,

failure_tests: bool = False,

post_parse: Callable[[str, ParseResults], str | None] | None = None,

file: TextIO | None = None,

with_line_numbers: bool = False,

*,

parseAll: bool = True,

fullDump: bool = True,

printResults: bool = True,

failureTests: bool = False,

postParse: Callable[[str, ParseResults], str | None] | None = None,

) → tuple[bool, list[tuple[str, ParseResults | Exception]]]

Deprecated since version 3.0.0: Use run_tests instead

run_tests(

tests: str | list[str],

parse_all: bool = True,

comment: ParserElement | str | None = '#',

full_dump: bool = True,

print_results: bool = True,

failure_tests: bool = False,

post_parse: Callable[[str, ParseResults], str | None] | None = None,

file: TextIO | None = None,

with_line_numbers: bool = False,

*,

parseAll: bool = True,

fullDump: bool = True,

printResults: bool = True,

failureTests: bool = False,

postParse: Callable[[str, ParseResults], str | None] | None = None,

) → tuple[bool, list[tuple[str, ParseResults | Exception]]]

Execute the parse expression on a series of test strings, showing each test, the parsed results or where the parse failed. Quick and easy way to run a parse expression against a list of sample strings.

Parameters:

• tests - a list of separate test strings, or a multiline string of test strings

• parse_all - (default= True) - flag to pass to parse_string when running tests

• comment - (default= '#') - expression for indicating embedded comments in the test string; pass None to disable comment filtering

• full_dump - (default= True) - dump results as list followed by results names in nested outline; if False, only dump nested list

• print_results - (default= True) prints test output to stdout

• failure_tests - (default= False) indicates if these tests are expected to fail parsing

• post_parse - (default= None) optional callback for successful parse results; called as fn(test_string, parse_results) and returns a string to be added to the test output

• file - (default= None) optional file-like object to which test output will be written; if None, will default to sys.stdout

• with_line_numbers - default= False) show test strings with line and column numbers

Returns: a (success, results) tuple, where success indicates that all tests succeeded (or failed if failure_tests is True), and the results contain a list of lines of each test’s output

Passing example:

number_expr = pyparsing_common.number.copy()

result = number_expr.run_tests('''
    # unsigned integer
    100
    # negative integer
    -100
    # float with scientific notation
    6.02e23
    # integer with scientific notation
    1e-12
    # negative decimal number without leading digit
    -.100
    ''')
print("Success" if result[0] else "Failed!")

prints:

# unsigned integer
100
[100]

# negative integer
-100
[-100]

# float with scientific notation
6.02e23
[6.02e+23]

# integer with scientific notation
1e-12
[1e-12]

# negative decimal number without leading digit
-.100
[-0.1]
Success

Failure-test example:

result = number_expr.run_tests('''
    # stray character
    100Z
    # too many '.'
    3.14.159
    ''', failure_tests=True)
print("Success" if result[0] else "Failed!")

prints:

# stray character
100Z
100Z
   ^
ParseException: Expected end of text, found 'Z' ...

# too many '.'
3.14.159
3.14.159
    ^
ParseException: Expected end of text, found '.' ...
FAIL: Expected end of text, found '.' ...
Success

Each test string must be on a single line. If you want to test a string that spans multiple lines, create a test like this:

expr = Word(alphanums)[1,...]
expr.run_tests(r"this is a test\n of strings that spans \n 3 lines")

(Note that this is a raw string literal, you must include the leading 'r'.)

scanString(

instring: str,

max_matches: int = _MAX_INT,

overlap: bool = False,

always_skip_whitespace=True,

*,

debug: bool = False,

**kwargs,

) → Generator[tuple[ParseResults, int, int], None, None]

Deprecated since version 3.0.0: Use scan_string instead

scan_string(

instring: str,

max_matches: int = _MAX_INT,

overlap: bool = False,

always_skip_whitespace=True,

*,

debug: bool = False,

**kwargs,

) → Generator[tuple[ParseResults, int, int], None, None]

Scan the input string for expression matches. Each match will return the matching tokens, start location, and end location. May be called with optional max_matches argument, to clip scanning after ‘n’ matches are found. If overlap is specified, then overlapping matches will be reported.

Note that the start and end locations are reported relative to the string being parsed. See parse_string for more information on parsing strings with embedded tabs.

Example:

source = "sldjf123lsdjjkf345sldkjf879lkjsfd987"
print(source)
for tokens, start, end in Word(alphas).scan_string(source):
    print(' '*start + '^'*(end-start))
    print(' '*start + tokens[0])

prints:

sldjf123lsdjjkf345sldkjf879lkjsfd987
^^^^^
sldjf
        ^^^^^^^
        lsdjjkf
                  ^^^^^^
                  sldkjf
                           ^^^^^^
                           lkjsfd

searchString(

instring: str,

max_matches: int = _MAX_INT,

*,

debug: bool = False,

**kwargs,

) → ParseResults

Deprecated since version 3.0.0: Use search_string instead

search_string(

instring: str,

max_matches: int = _MAX_INT,

*,

debug: bool = False,

**kwargs,

) → ParseResults

Another extension to scan_string, simplifying the access to the tokens found to match the given parse expression. May be called with optional max_matches argument, to clip searching after ‘n’ matches are found.

Example:

quote = '''More than Iron, more than Lead,
more than Gold I need Electricity'''

# a capitalized word starts with an uppercase letter,
# followed by zero or more lowercase letters
cap_word = Word(alphas.upper(), alphas.lower())

print(cap_word.search_string(quote))

# the sum() builtin can be used to merge results
# into a single ParseResults object
print(sum(cap_word.search_string(quote)))

prints:

[['More'], ['Iron'], ['Lead'], ['Gold'], ['I'], ['Electricity']]
['More', 'Iron', 'Lead', 'Gold', 'I', 'Electricity']

setBreak(break_flag: bool = True) → ParserElement

Deprecated since version 3.0.0: Use set_break instead

setDebug(flag: bool = True, recurse: bool = False) → ParserElement

Deprecated since version 3.0.0: Use set_debug instead

setDebugActions(

start_action: Callable[[str, int, ParserElement, bool], None],

success_action: Callable[[str, int, int, ParserElement, ParseResults, bool], None],

exception_action: Callable[[str, int, ParserElement, Exception, bool], None],

) → ParserElement

Deprecated since version 3.0.0: Use set_debug_actions instead

static setDefaultWhitespaceChars(chars: str) → None

Deprecated since version 3.0.0: Use set_default_whitespace_chars instead

setFailAction(

fn: Callable[[str, int, ParserElement, Exception], None],

) → ParserElement

Deprecated since version 3.0.0: Use set_fail_action instead

setName(name: str | None) → ParserElement

Deprecated since version 3.0.0: Use set_name instead

setParseAction(

*fns: Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any],

call_during_try: bool = False,

**kwargs: Any,

) → ParserElement

Deprecated since version 3.0.0: Use set_parse_action instead

setResultsName(

name: str,

list_all_matches: bool = False,

**kwargs,

) → ParserElement

Deprecated since version 3.0.0: Use set_results_name instead

setWhitespaceChars(

chars: set[str] | str,

copy_defaults: bool = False,

) → ParserElement

Deprecated since version 3.0.0: Use set_whitespace_chars instead

set_break(break_flag: bool = True) → ParserElement

Method to invoke the Python pdb debugger when this element is about to be parsed. Set break_flag to True to enable, False to disable.

set_debug(flag: bool = True, recurse: bool = False) → ParserElement

Enable display of debugging messages while doing pattern matching. Set flag to True to enable, False to disable. Set recurse to True to set the debug flag on this expression and all sub-expressions.

Example:

wd = Word(alphas).set_name("alphaword")
integer = Word(nums).set_name("numword")
term = wd | integer

# turn on debugging for wd
wd.set_debug()

term[1, ...].parse_string("abc 123 xyz 890")

prints:

Match alphaword at loc 0(1,1)
  abc 123 xyz 890
  ^
Matched alphaword -> ['abc']
Match alphaword at loc 4(1,5)
  abc 123 xyz 890
      ^
Match alphaword failed, ParseException raised: Expected alphaword, ...
Match alphaword at loc 8(1,9)
  abc 123 xyz 890
          ^
Matched alphaword -> ['xyz']
Match alphaword at loc 12(1,13)
  abc 123 xyz 890
              ^
Match alphaword failed, ParseException raised: Expected alphaword, ...
  abc 123 xyz 890
                 ^
Match alphaword failed, ParseException raised: Expected alphaword, found end of text ...

The output shown is that produced by the default debug actions - custom debug actions can be specified using set_debug_actions(). Prior to attempting to match the wd expression, the debugging message "Match <exprname> at loc <n>(<line>,<col>)" is shown. Then if the parse succeeds, a "Matched" message is shown, or an "Exception raised" message is shown. Also note the use of set_name() to assign a human-readable name to the expression, which makes debugging and exception messages easier to understand - for instance, the default name created for the Word expression without calling set_name() is "W:(A-Za-z)".

Changed in version 3.1.0: recurse argument added.

set_debug_actions(

start_action: Callable[[str, int, ParserElement, bool], None],

success_action: Callable[[str, int, int, ParserElement, ParseResults, bool], None],

exception_action: Callable[[str, int, ParserElement, Exception, bool], None],

) → ParserElement

Customize display of debugging messages while doing pattern matching:

Parameters:

• start_action –

  method to be called when an expression is about to be parsed; should have the signature:

  fn(input_string: str,
     location: int,
     expression: ParserElement,
     cache_hit: bool)
  

• success_action –

  method to be called when an expression has successfully parsed; should have the signature:

  fn(input_string: str,
     start_location: int,
     end_location: int,
     expression: ParserELement,
     parsed_tokens: ParseResults,
     cache_hit: bool)
  

• exception_action –

  method to be called when expression fails to parse; should have the signature:

  fn(input_string: str,
     location: int,
     expression: ParserElement,
     exception: Exception,
     cache_hit: bool)
  

static set_default_whitespace_chars(chars: str) → None

Overrides the default whitespace chars

Example:

# default whitespace chars are space, <TAB> and newline
>>> Word(alphas)[1, ...].parse_string("abc def\nghi jkl")
ParseResults(['abc', 'def', 'ghi', 'jkl'], {})

# change to just treat newline as significant
>>> ParserElement.set_default_whitespace_chars(" \t")
>>> Word(alphas)[1, ...].parse_string("abc def\nghi jkl")
ParseResults(['abc', 'def'], {})

# Reset to default
>>> ParserElement.set_default_whitespace_chars(" \n\t\r")

set_fail_action(

fn: Callable[[str, int, ParserElement, Exception], None],

) → ParserElement

Define action to perform if parsing fails at this expression. Fail acton fn is a callable function that takes the arguments fn(s, loc, expr, err) where:

• s = string being parsed

• loc = location where expression match was attempted and failed

• expr = the parse expression that failed

• err = the exception thrown

The function returns no value. It may throw ParseFatalException if it is desired to stop parsing immediately.

set_name(name: str | None) → ParserElement

Define name for this expression, makes debugging and exception messages clearer. If __diag__.enable_debug_on_named_expressions is set to True, setting a name will also enable debug for this expression.

If name is None, clears any custom name for this expression, and clears the debug flag is it was enabled via __diag__.enable_debug_on_named_expressions.

Example:

>>> integer = Word(nums)
>>> integer.parse_string("ABC")
Traceback (most recent call last):
ParseException: Expected W:(0-9) (at char 0), (line:1, col:1)

>>> integer.set_name("integer")
integer
>>> integer.parse_string("ABC")
Traceback (most recent call last):
ParseException: Expected integer (at char 0), (line:1, col:1)

Changed in version 3.1.0: Accept None as the name argument.

set_parse_action(

*fns: Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any],

call_during_try: bool = False,

**kwargs: Any,

) → ParserElement

Define one or more actions to perform when successfully matching parse element definition.

Parse actions can be called to perform data conversions, do extra validation, update external data structures, or enhance or replace the parsed tokens. Each parse action fn is a callable method with 0-3 arguments, called as fn(s, loc, toks) , fn(loc, toks) , fn(toks) , or just fn() , where:

• s = the original string being parsed (see note below)

• loc = the location of the matching substring

• toks = a list of the matched tokens, packaged as a ParseResults object

The parsed tokens are passed to the parse action as ParseResults. They can be modified in place using list-style append, extend, and pop operations to update the parsed list elements; and with dictionary-style item set and del operations to add, update, or remove any named results. If the tokens are modified in place, it is not necessary to return them with a return statement.

Parse actions can also completely replace the given tokens, with another ParseResults object, or with some entirely different object (common for parse actions that perform data conversions). A convenient way to build a new parse result is to define the values using a dict, and then create the return value using ParseResults.from_dict.

If None is passed as the fn parse action, all previously added parse actions for this expression are cleared.

Optional keyword arguments:

Parameters:

call_during_try – (default= False) indicate if parse action should be run during lookaheads and alternate testing. For parse actions that have side effects, it is important to only call the parse action once it is determined that it is being called as part of a successful parse. For parse actions that perform additional validation, then call_during_try should be passed as True, so that the validation code is included in the preliminary “try” parses.

Note

The default parsing behavior is to expand tabs in the input string before starting the parsing process. See parse_string() for more information on parsing strings containing <TAB> s, and suggested methods to maintain a consistent view of the parsed string, the parse location, and line and column positions within the parsed string.

Example: Parse dates in the form YYYY/MM/DD

Setup code:

def convert_to_int(toks):
    '''a parse action to convert toks from str to int
    at parse time'''
    return int(toks[0])

def is_valid_date(instring, loc, toks):
    '''a parse action to verify that the date is a valid date'''
    from datetime import date
    year, month, day = toks[::2]
    try:
        date(year, month, day)
    except ValueError:
        raise ParseException(instring, loc, "invalid date given")

integer = Word(nums)
date_str = integer + '/' + integer + '/' + integer

# add parse actions
integer.set_parse_action(convert_to_int)
date_str.set_parse_action(is_valid_date)

Successful parse - note that integer fields are converted to ints:

print(date_str.parse_string("1999/12/31"))

prints:

[1999, '/', 12, '/', 31]

Failure - invalid date:

date_str.parse_string("1999/13/31")

prints:

Traceback (most recent call last):
ParseException: invalid date given, found '1999' ...

set_results_name(

name: str,

list_all_matches: bool = False,

**kwargs,

) → ParserElement

Define name for referencing matching tokens as a nested attribute of the returned parse results.

Normally, results names are assigned as you would assign keys in a dict: any existing value is overwritten by later values. If it is necessary to keep all values captured for a particular results name, call set_results_name with list_all_matches = True.

NOTE: set_results_name returns a copy of the original ParserElement object; this is so that the client can define a basic element, such as an integer, and reference it in multiple places with different names.

You can also set results names using the abbreviated syntax, expr("name") in place of expr.set_results_name("name") - see __call__(). If list_all_matches is required, use expr("name*").

Example:

integer = Word(nums)
date_str = (integer.set_results_name("year") + '/'
            + integer.set_results_name("month") + '/'
            + integer.set_results_name("day"))

# equivalent form:
date_str = integer("year") + '/' + integer("month") + '/' + integer("day")

set_whitespace_chars(

chars: set[str] | str,

copy_defaults: bool = False,

) → ParserElement

Overrides the default whitespace chars

split(

instring: str,

maxsplit: int = _MAX_INT,

include_separators: bool = False,

**kwargs,

) → Generator[str, None, None]

Generator method to split a string using the given expression as a separator. May be called with optional maxsplit argument, to limit the number of splits; and the optional include_separators argument (default= False), if the separating matching text should be included in the split results.

Example:

punc = one_of(list(".,;:/-!?"))
print(list(punc.split(
    "This, this?, this sentence, is badly punctuated!")))

prints:

['This', ' this', '', ' this sentence', ' is badly punctuated', '']

suppress() → ParserElement

Suppresses the output of this ParserElement; useful to keep punctuation from cluttering up returned output.

suppress_warning(

warning_type: Diagnostics,

) → ParserElement

Suppress warnings emitted for a particular diagnostic on this expression.

Example:

>>> label = pp.Word(pp.alphas)

# Normally using an empty Forward in a grammar
# would print a warning, but we can suppress that
>>> base = pp.Forward().suppress_warning(
...     pp.Diagnostics.warn_on_parse_using_empty_Forward)

>>> grammar = base | label
>>> print(grammar.parse_string("x"))
['x']

transformString(instring: str, *, debug: bool = False) → str

Deprecated since version 3.0.0: Use transform_string instead

transform_string(instring: str, *, debug: bool = False) → str

Extension to scan_string, to modify matching text with modified tokens that may be returned from a parse action. To use transform_string, define a grammar and attach a parse action to it that modifies the returned token list. Invoking transform_string() on a target string will then scan for matches, and replace the matched text patterns according to the logic in the parse action. transform_string() returns the resulting transformed string.

Example:

quote = '''now is the winter of our discontent,
made glorious summer by this sun of york.'''

wd = Word(alphas)
wd.set_parse_action(lambda toks: toks[0].title())

print(wd.transform_string(quote))

prints:

Now Is The Winter Of Our Discontent,
Made Glorious Summer By This Sun Of York.

tryParse(

instring: str,

loc: int,

*,

raise_fatal: bool = False,

do_actions: bool = False,

) → int

Deprecated since version 3.0.0: Use try_parse instead

classmethod using_each(seq, **class_kwargs)

Yields a sequence of class(obj, **class_kwargs) for obj in seq.

Example:

LPAR, RPAR, LBRACE, RBRACE, SEMI = Suppress.using_each("(){};")

Added in version 3.1.0.

validate(validateTrace=None) → None

Deprecated since version 3.0.0: Do not use to check for left recursion.

Check defined expressions for valid structure, check for infinite recursive definitions.

verbose_stacktrace: bool = False

visit_all()

General-purpose method to yield all expressions and sub-expressions in a grammar. Typically just for internal use.

class PositionToken

Bases: Token

class PrecededBy(expr: ParserElement | str, retreat: int = 0)

Bases: ParseElementEnhance

Lookbehind matching of the given parse expression. PrecededBy does not advance the parsing position within the input string, it only verifies that the specified parse expression matches prior to the current position. PrecededBy always returns a null token list, but if a results name is defined on the given expression, it is returned.

Parameters:

• expr - expression that must match prior to the current parse location

• retreat - (default= None) - (int) maximum number of characters to lookbehind prior to the current parse location

If the lookbehind expression is a string, Literal, Keyword, or a Word or CharsNotIn with a specified exact or maximum length, then the retreat parameter is not required. Otherwise, retreat must be specified to give a maximum number of characters to look back from the current parse position for a lookbehind match.

Example:

# VB-style variable names with type prefixes
int_var = PrecededBy("#") + pyparsing_common.identifier
str_var = PrecededBy("$") + pyparsing_common.identifier

exception PyparsingDeprecationWarning

Bases: PyparsingWarning, DeprecationWarning

Base warning class for all pyparsing deprecation warnings

exception PyparsingDiagnosticWarning

Bases: PyparsingWarning

Base warning class for all pyparsing diagnostic warnings

exception PyparsingWarning

Bases: UserWarning

Base warning class for all pyparsing warnings

class QuotedString(

quote_char: str = '',

esc_char: str | None = None,

esc_quote: str | None = None,

multiline: bool = False,

unquote_results: bool = True,

end_quote_char: str | None = None,

convert_whitespace_escapes: bool = True,

**kwargs,

)

Bases: Token

Token for matching strings that are delimited by quoting characters.

Defined with the following parameters:

• quote_char - string of one or more characters defining the quote delimiting string

• esc_char - character to re_escape quotes, typically backslash (default= None)

• esc_quote - special quote sequence to re_escape an embedded quote string (such as SQL’s "" to re_escape an embedded ") (default= None)

• multiline - boolean indicating whether quotes can span multiple lines (default= False)

• unquote_results - boolean indicating whether the matched text should be unquoted (default= True)

• end_quote_char - string of one or more characters defining the end of the quote delimited string (default= None => same as quote_char)

• convert_whitespace_escapes - convert escaped whitespace ('\t', '\n', etc.) to actual whitespace (default= True)

Caution

convert_whitespace_escapes has no effect if unquote_results is False.

Example:

>>> qs = QuotedString('"')
>>> print(qs.search_string('lsjdf "This is the quote" sldjf'))
[['This is the quote']]
>>> complex_qs = QuotedString('{{', end_quote_char='}}')
>>> print(complex_qs.search_string(
...    'lsjdf {{This is the "quote"}} sldjf'))
[['This is the "quote"']]
>>> sql_qs = QuotedString('"', esc_quote='""')
>>> print(sql_qs.search_string(
...     'lsjdf "This is the quote with ""embedded"" quotes" sldjf'))
[['This is the quote with "embedded" quotes']]

ws_map = {'\\f': '\x0c', '\\n': '\n', '\\r': '\r', '\\t': '\t'}

exception RecursiveGrammarException(parseElementList)

Bases: Exception

Deprecated since version 3.0.0: Only used by the deprecated ParserElement.validate().

Exception thrown by ParserElement.validate if the grammar could be left-recursive; parser may need to enable left recursion using ParserElement.enable_left_recursion

__str__() → str

Return str(self).

class Regex(

pattern: Any,

flags: RegexFlag | int = 0,

as_group_list: bool = False,

as_match: bool = False,

**kwargs,

)

Bases: Token

Token for matching strings that match a given regular expression. Defined with string specifying the regular expression in a form recognized by the stdlib Python re module. If the given regex contains named groups (defined using (?P<name>...)), these will be preserved as named ParseResults.

If instead of the Python stdlib re module you wish to use a different RE module (such as the regex module), you can do so by building your Regex object with a compiled RE that was compiled using regex.

The parameters pattern and flags are passed to the re.compile() function as-is. See the Python re module module for an explanation of the acceptable patterns and flags.

Example:

realnum = Regex(r"[+-]?\d+\.\d*")
# ref: https://stackoverflow.com/questions/267399/how-do-you-match-only-valid-roman-numerals-with-a-regular-expression
roman = Regex(r"M{0,4}(CM|CD|D?{0,3})(XC|XL|L?X{0,3})(IX|IV|V?I{0,3})")

# named fields in a regex will be returned as named results
date = Regex(r'(?P<year>\d{4})-(?P<month>\d\d?)-(?P<day>\d\d?)')

# the Regex class will accept regular expressions compiled using the
# re module
import re
parser = pp.Regex(re.compile(r'[0-9]'))

copy() → Regex

Returns a copy of this expression.

Generally only used internally by pyparsing.

property re: Pattern

Property returning the compiled regular expression for this Regex.

Generally only used internally by pyparsing.

property re_match: Callable[[str, int], Any]

sub(repl: str) → ParserElement

Return Regex with an attached parse action to transform the parsed result as if called using re.sub(expr, repl, string).

Example:

make_html = Regex(r"(\w+):(.*?):").sub(r"<\1>\2</\1>")
print(make_html.transform_string("h1:main title:"))

<h1>main title</h1>

class SkipTo(

other: ParserElement | str,

include: bool = False,

ignore: ParserElement | str | None = None,

fail_on: ParserElement | str | None = None,

**kwargs,

)

Bases: ParseElementEnhance

Token for skipping over all undefined text until the matched expression is found.

Parameters:

• expr – target expression marking the end of the data to be skipped

• include – if True, the target expression is also parsed (the skipped text and target expression are returned as a 2-element list) (default= False).

• ignore – (default= None) used to define grammars (typically quoted strings and comments) that might contain false matches to the target expression

• fail_on – (default= None) define expressions that are not allowed to be included in the skipped test; if found before the target expression is found, the SkipTo is not a match

Example:

report = '''
    Outstanding Issues Report - 1 Jan 2000

       # | Severity | Description                               |  Days Open
    -----+----------+-------------------------------------------+-----------
     101 | Critical | Intermittent system crash                 |          6
      94 | Cosmetic | Spelling error on Login ('log|n')         |         14
      79 | Minor    | System slow when running too many reports |         47
    '''
integer = Word(nums)
SEP = Suppress('|')
# use SkipTo to simply match everything up until the next SEP
# - ignore quoted strings, so that a '|' character inside a quoted string does not match
# - parse action will call token.strip() for each matched token, i.e., the description body
string_data = SkipTo(SEP, ignore=quoted_string)
string_data.set_parse_action(token_map(str.strip))
ticket_expr = (integer("issue_num") + SEP
              + string_data("sev") + SEP
              + string_data("desc") + SEP
              + integer("days_open"))

for tkt in ticket_expr.search_string(report):
    print(tkt.dump())

prints:

['101', 'Critical', 'Intermittent system crash', '6']
- days_open: '6'
- desc: 'Intermittent system crash'
- issue_num: '101'
- sev: 'Critical'
['94', 'Cosmetic', "Spelling error on Login ('log|n')", '14']
- days_open: '14'
- desc: "Spelling error on Login ('log|n')"
- issue_num: '94'
- sev: 'Cosmetic'
['79', 'Minor', 'System slow when running too many reports', '47']
- days_open: '47'
- desc: 'System slow when running too many reports'
- issue_num: '79'
- sev: 'Minor'

ignore(expr)

Define expression to be ignored (e.g., comments) while doing pattern matching; may be called repeatedly, to define multiple comment or other ignorable patterns.

class StringEnd

Bases: PositionToken

Matches if current position is at the end of the parse string

class StringStart

Bases: PositionToken

Matches if current position is at the beginning of the parse string

class Suppress(expr: ParserElement | str, savelist: bool = False)

Bases: TokenConverter

Converter for ignoring the results of a parsed expression.

Example:

>>> source = "a, b, c,d"
>>> wd = Word(alphas)
>>> wd_list1 = wd + (',' + wd)[...]
>>> print(wd_list1.parse_string(source))
['a', ',', 'b', ',', 'c', ',', 'd']

# often, delimiters that are useful during parsing are just in the
# way afterward - use Suppress to keep them out of the parsed output
>>> wd_list2 = wd + (Suppress(',') + wd)[...]
>>> print(wd_list2.parse_string(source))
['a', 'b', 'c', 'd']

# Skipped text (using '...') can be suppressed as well
>>> source = "lead in START relevant text END trailing text"
>>> start_marker = Keyword("START")
>>> end_marker = Keyword("END")
>>> find_body = Suppress(...) + start_marker + ... + end_marker
>>> print(find_body.parse_string(source))
['START', 'relevant text ', 'END']

(See also DelimitedList.)

__add__(other) → ParserElement

Implementation of + operator - returns And. Adding strings to a ParserElement converts them to Literals by default.

Example:

greet = Word(alphas) + "," + Word(alphas) + "!"
hello = "Hello, World!"
print(hello, "->", greet.parse_string(hello))

prints:

Hello, World! -> ['Hello', ',', 'World', '!']

... may be used as a parse expression as a short form of SkipTo:

Literal('start') + ... + Literal('end')

is equivalent to:

Literal('start') + SkipTo('end')("_skipped*") + Literal('end')

Note that the skipped text is returned with ‘_skipped’ as a results name, and to support having multiple skips in the same parser, the value returned is a list of all skipped text.

__sub__(other) → ParserElement

Implementation of - operator, returns And with error stop

suppress() → ParserElement

Suppresses the output of this ParserElement; useful to keep punctuation from cluttering up returned output.

class Tag(tag_name: str, value: Any = True)

Bases: Token

A meta-element for inserting a named result into the parsed tokens that may be checked later in a parse action or while processing the parsed results. Accepts an optional tag value, defaulting to True.

Example:

>>> end_punc = "." | ("!" + Tag("enthusiastic"))
>>> greeting = "Hello," + Word(alphas) + end_punc

>>> result = greeting.parse_string("Hello, World.")
>>> print(result.dump())
['Hello,', 'World', '.']

>>> result = greeting.parse_string("Hello, World!")
>>> print(result.dump())
['Hello,', 'World', '!']
- enthusiastic: True

.. versionadded:: 3.1.0

class Token

Bases: ParserElement

Abstract ParserElement subclass, for defining atomic matching patterns.

class TokenConverter(expr: ParserElement | str, savelist=False)

Bases: ParseElementEnhance

Abstract subclass of ParseElementEnhance, for converting parsed results.

class White(ws: str = ' \t\r\n', min: int = 1, max: int = 0, exact: int = 0)

Bases: Token

Special matching class for matching whitespace. Normally, whitespace is ignored by pyparsing grammars. This class is included when some whitespace structures are significant. Define with a string containing the whitespace characters to be matched; default is " \t\r\n". Also takes optional min, max, and exact arguments, as defined for the Word class.

whiteStrs = {'\t': '<TAB>', '\n': '<LF>', '\x0c': '<FF>', '\r': '<CR>', ' ': '<SP>', '\xa0': '<NBSP>', '\u1680': '<OGHAM_SPACE_MARK>', '\u180e': '<MONGOLIAN_VOWEL_SEPARATOR>', '\u2000': '<EN_QUAD>', '\u2001': '<EM_QUAD>', '\u2002': '<EN_SPACE>', '\u2003': '<EM_SPACE>', '\u2004': '<THREE-PER-EM_SPACE>', '\u2005': '<FOUR-PER-EM_SPACE>', '\u2006': '<SIX-PER-EM_SPACE>', '\u2007': '<FIGURE_SPACE>', '\u2008': '<PUNCTUATION_SPACE>', '\u2009': '<THIN_SPACE>', '\u200a': '<HAIR_SPACE>', '\u200b': '<ZERO_WIDTH_SPACE>', '\u202f': '<NNBSP>', '\u205f': '<MMSP>', '\u3000': '<IDEOGRAPHIC_SPACE>'}

class Word(

init_chars: str = '',

body_chars: str | None = None,

min: int = 1,

max: int = 0,

exact: int = 0,

as_keyword: bool = False,

exclude_chars: str | None = None,

**kwargs,

)

Bases: Token

Token for matching words composed of allowed character sets.

Parameters:

• init_chars - string of all characters that should be used to match as a word; “ABC” will match “AAA”, “ABAB”, “CBAC”, etc.; if body_chars is also specified, then this is the string of initial characters

• body_chars - string of characters that can be used for matching after a matched initial character as given in init_chars; if omitted, same as the initial characters (default=``None``)

• min - minimum number of characters to match (default=1)

• max - maximum number of characters to match (default=0)

• exact - exact number of characters to match (default=0)

• as_keyword - match as a keyword (default=``False``)

• exclude_chars - characters that might be found in the input body_chars string but which should not be accepted for matching ;useful to define a word of all printables except for one or two characters, for instance (default=``None``)

srange is useful for defining custom character set strings for defining Word expressions, using range notation from regular expression character sets.

A common mistake is to use Word to match a specific literal string, as in Word("Address"). Remember that Word uses the string argument to define sets of matchable characters. This expression would match “Add”, “AAA”, “dAred”, or any other word made up of the characters ‘A’, ‘d’, ‘r’, ‘e’, and ‘s’. To match an exact literal string, use Literal or Keyword.

pyparsing includes helper strings for building Words:

• alphas

• nums

• alphanums

• hexnums

• alphas8bit (alphabetic characters in ASCII range 128-255 - accented, tilded, umlauted, etc.)

• punc8bit (non-alphabetic characters in ASCII range 128-255 - currency, symbols, superscripts, diacriticals, etc.)

• printables (any non-whitespace character)

alphas, nums, and printables are also defined in several Unicode sets - see pyparsing_unicode.

Example:

# a word composed of digits
integer = Word(nums)
# Two equivalent alternate forms:
Word("0123456789")
Word(srange("[0-9]"))

# a word with a leading capital, and zero or more lowercase
capitalized_word = Word(alphas.upper(), alphas.lower())

# hostnames are alphanumeric, with leading alpha, and '-'
hostname = Word(alphas, alphanums + '-')

# roman numeral
# (not a strict parser, accepts invalid mix of characters)
roman = Word("IVXLCDM")

# any string of non-whitespace characters, except for ','
csv_value = Word(printables, exclude_chars=",")

Raises:

ValueError – If min and max are both specified and the test min <= max fails.

Changed in version 3.1.0: Raises ValueError if min > max.

copy() → Word

Returns a copy of this expression.

Generally only used internally by pyparsing.

property initChars: set[str]

Deprecated since version 3.3.0: use init_chars instead.

Property returning the initial chars to be used when matching this Word expression. If no body chars were specified, the initial characters will also be the body characters.

class WordEnd(word_chars: str = printables, **kwargs)

Bases: PositionToken

Matches if the current position is at the end of a Word, and is not followed by any character in a given set of word_chars (default= printables). To emulate the  behavior of regular expressions, use WordEnd(alphanums). WordEnd will also match at the end of the string being parsed, or at the end of a line.

class WordStart(word_chars: str = printables, **kwargs)

Bases: PositionToken

Matches if the current position is at the beginning of a Word, and is not preceded by any character in a given set of word_chars (default= printables). To emulate the  behavior of regular expressions, use WordStart(alphanums). WordStart will also match at the beginning of the string being parsed, or at the beginning of a line.

class ZeroOrMore(

expr: str | ParserElement,

stop_on: ParserElement | str | None = None,

**kwargs,

)

Bases: _MultipleMatch

Optional repetition of zero or more of the given expression.

Parameters:

• expr - expression that must match zero or more times

• stop_on - expression for a terminating sentinel (only required if the sentinel would ordinarily match the repetition expression) - (default= None)

Example: similar to OneOrMore

autoname_elements() → None

Utility to simplify mass-naming of parser elements, for generating railroad diagram with named subdiagrams.

col(loc: int, strg: str) → int

Returns current column within a string, counting newlines as line separators. The first column is number 1.

Note: the default parsing behavior is to expand tabs in the input string before starting the parsing process. See ParserElement.parse_string() for more information on parsing strings containing <TAB> s, and suggested methods to maintain a consistent view of the parsed string, the parse location, and line and column positions within the parsed string.

common

alias of pyparsing_common

conditionAsParseAction(

fn: Callable[[], bool] | Callable[[ParseResults], bool] | Callable[[int, ParseResults], bool] | Callable[[str, int, ParseResults], bool],

message: str | None = None,

fatal: bool = False,

) → Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any]

Deprecated since version 3.0.0: Use condition_as_parse_action instead

condition_as_parse_action(

fn: Callable[[], bool] | Callable[[ParseResults], bool] | Callable[[int, ParseResults], bool] | Callable[[str, int, ParseResults], bool],

message: str | None = None,

fatal: bool = False,

) → Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any]

Function to convert a simple predicate function that returns True or False into a parse action. Can be used in places when a parse action is required and ParserElement.add_condition() cannot be used (such as when adding a condition to an operator level in infix_notation).

Optional keyword arguments:

Parameters:

• message – define a custom message to be used in the raised exception

• fatal – if True, will raise ParseFatalException to stop parsing immediately; otherwise will raise ParseException

countedArray(

expr: ParserElement,

int_expr: ParserElement | None = None,

**kwargs,

) → ParserElement

Deprecated since version 3.0.0: Use counted_array instead

counted_array(

expr: ParserElement,

int_expr: ParserElement | None = None,

**kwargs,

) → ParserElement

Helper to define a counted list of expressions.

This helper defines a pattern of the form:

integer expr expr expr...

where the leading integer tells how many expr expressions follow. The matched tokens returns the array of expr tokens as a list - the leading count token is suppressed.

If int_expr is specified, it should be a pyparsing expression that produces an integer value.

Examples:

>>> counted_array(Word(alphas)).parse_string('2 ab cd ef')
ParseResults(['ab', 'cd'], {})

• In this parser, the leading integer value is given in binary, ‘10’ indicating that 2 values are in the array:

  >>> binary_constant = Word('01').set_parse_action(lambda t: int(t[0], 2))
  >>> counted_array(Word(alphas), int_expr=binary_constant
  ...     ).parse_string('10 ab cd ef')
  ParseResults(['ab', 'cd'], {})
  

• If other fields must be parsed after the count but before the list items, give the fields results names and they will be preserved in the returned ParseResults:

  >>> ppc = pyparsing.common
  >>> count_with_metadata = ppc.integer + Word(alphas)("type")
  >>> typed_array = counted_array(Word(alphanums),
  ...     int_expr=count_with_metadata)("items")
  >>> result = typed_array.parse_string("3 bool True True False")
  >>> print(result.dump())
  ['True', 'True', 'False']
  - items: ['True', 'True', 'False']
  - type: 'bool'
  

delimitedList(

expr: str | ParserElement,

delim: str | ParserElement = ',',

combine: bool = False,

min: Optional[int] = None,

max: Optional[int] = None,

*,

allow_trailing_delim: bool = False,

) → None

Deprecated since version 3.0.0: Use DelimitedList instead

delimited_list(

expr: str | ParserElement,

delim: str | ParserElement = ',',

combine: bool = False,

min: Optional[int] = None,

max: Optional[int] = None,

*,

allow_trailing_delim: bool = False,

) → None

Deprecated since version 3.0.0: Use DelimitedList instead

dictOf(

key: ParserElement,

value: ParserElement,

) → Dict

Deprecated since version 3.0.0: Use dict_of instead

dict_of(

key: ParserElement,

value: ParserElement,

) → Dict

Helper to easily and clearly define a dictionary by specifying the respective patterns for the key and value. Takes care of defining the Dict, ZeroOrMore, and Group tokens in the proper order. The key pattern can include delimiting markers or punctuation, as long as they are suppressed, thereby leaving the significant key text. The value pattern can include named results, so that the Dict results can include named token fields.

Example:

>>> text = "shape: SQUARE posn: upper left color: light blue texture: burlap"

>>> data_word = Word(alphas)
>>> label = data_word + FollowedBy(':')
>>> attr_expr = (
...    label
...    + Suppress(':')
...    + OneOrMore(data_word, stop_on=label)
...    .set_parse_action(' '.join))
>>> print(attr_expr[1, ...].parse_string(text).dump())
['shape', 'SQUARE', 'posn', 'upper left', 'color', 'light blue', 'texture', 'burlap']

>>> attr_label = label
>>> attr_value = Suppress(':') + OneOrMore(data_word, stop_on=label
...   ).set_parse_action(' '.join)

# similar to Dict, but simpler call format
>>> result = dict_of(attr_label, attr_value).parse_string(text)
>>> print(result.dump())
[['shape', 'SQUARE'], ['posn', 'upper left'], ['color', 'light blue'], ['texture', 'burlap']]
- color: 'light blue'
- posn: 'upper left'
- shape: 'SQUARE'
- texture: 'burlap'
[0]:
  ['shape', 'SQUARE']
[1]:
  ['posn', 'upper left']
[2]:
  ['color', 'light blue']
[3]:
  ['texture', 'burlap']

>>> print(result['shape'])
SQUARE
>>> print(result.shape)  # object attribute access works too
SQUARE
>>> print(result.as_dict())
{'shape': 'SQUARE', 'posn': 'upper left', 'color': 'light blue', 'texture': 'burlap'}

indentedBlock(blockStatementExpr, indentStack, indent=True, backup_stacks=[])

Deprecated since version 3.0.0: Use the IndentedBlock class instead. Note that IndentedBlock has a difference method signature.

Helper method for defining space-delimited indentation blocks, such as those used to define block statements in Python source code.

Parameters:

• blockStatementExpr – expression defining syntax of statement that is repeated within the indented block

• indentStack – list created by caller to manage indentation stack (multiple statementWithIndentedBlock expressions within a single grammar should share a common indentStack)

• indent – boolean indicating whether block must be indented beyond the current level; set to False for block of left-most statements

A valid block must contain at least one blockStatement.

(Note that indentedBlock uses internal parse actions which make it incompatible with packrat parsing.)

Example:

data = '''
def A(z):
  A1
  B = 100
  G = A2
  A2
  A3
B
def BB(a,b,c):
  BB1
  def BBA():
    bba1
    bba2
    bba3
C
D
def spam(x,y):
     def eggs(z):
         pass
'''

indentStack = [1]
stmt = Forward()

identifier = Word(alphas, alphanums)
funcDecl = ("def" + identifier + Group("(" + Opt(delimitedList(identifier)) + ")") + ":")
func_body = indentedBlock(stmt, indentStack)
funcDef = Group(funcDecl + func_body)

rvalue = Forward()
funcCall = Group(identifier + "(" + Opt(delimitedList(rvalue)) + ")")
rvalue << (funcCall | identifier | Word(nums))
assignment = Group(identifier + "=" + rvalue)
stmt << (funcDef | assignment | identifier)

module_body = stmt[1, ...]

parseTree = module_body.parseString(data)
parseTree.pprint()

prints:

[['def',
  'A',
  ['(', 'z', ')'],
  ':',
  [['A1'], [['B', '=', '100']], [['G', '=', 'A2']], ['A2'], ['A3']]],
 'B',
 ['def',
  'BB',
  ['(', 'a', 'b', 'c', ')'],
  ':',
  [['BB1'], [['def', 'BBA', ['(', ')'], ':', [['bba1'], ['bba2'], ['bba3']]]]]],
 'C',
 'D',
 ['def',
  'spam',
  ['(', 'x', 'y', ')'],
  ':',
  [[['def', 'eggs', ['(', 'z', ')'], ':', [['pass']]]]]]]

infixNotation(

base_expr: ParserElement,

op_list: list[tuple[ParserElement | str | tuple[ParserElement | str, ParserElement | str], int, OpAssoc, Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any] | None] | tuple[ParserElement | str | tuple[ParserElement | str, ParserElement | str], int, OpAssoc]],

lpar: str | ParserElement = Suppress('('),

rpar: str | ParserElement = Suppress(')'),

) → Forward

Deprecated since version 3.0.0: Use infix_notation instead

infix_notation(

base_expr: ParserElement,

op_list: list[tuple[ParserElement | str | tuple[ParserElement | str, ParserElement | str], int, OpAssoc, Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any] | None] | tuple[ParserElement | str | tuple[ParserElement | str, ParserElement | str], int, OpAssoc]],

lpar: str | ParserElement = Suppress('('),

rpar: str | ParserElement = Suppress(')'),

) → Forward

Helper method for constructing grammars of expressions made up of operators working in a precedence hierarchy. Operators may be unary or binary, left- or right-associative. Parse actions can also be attached to operator expressions. The generated parser will also recognize the use of parentheses to override operator precedences (see example below).

Note: if you define a deep operator list, you may see performance issues when using infix_notation. See ParserElement.enable_packrat for a mechanism to potentially improve your parser performance.

Parameters:

Parameters:

• base_expr – expression representing the most basic operand to be used in the expression

• op_list –

  list of tuples, one for each operator precedence level in the expression grammar; each tuple is of the form (op_expr, num_operands, right_left_assoc, (optional)parse_action), where:

  • op_expr is the pyparsing expression for the operator; may also be a string, which will be converted to a Literal; if num_operands is 3, op_expr is a tuple of two expressions, for the two operators separating the 3 terms

  • num_operands is the number of terms for this operator (must be 1, 2, or 3)

  • right_left_assoc is the indicator whether the operator is right or left associative, using the pyparsing-defined constants OpAssoc.RIGHT and OpAssoc.LEFT.

  • parse_action is the parse action to be associated with expressions matching this operator expression (the parse action tuple member may be omitted); if the parse action is passed a tuple or list of functions, this is equivalent to calling set_parse_action(*fn) (ParserElement.set_parse_action)

• lpar – expression for matching left-parentheses; if passed as a str, then will be parsed as Suppress(lpar). If lpar is passed as an expression (such as Literal('(')), then it will be kept in the parsed results, and grouped with them. (default= Suppress('('))

• rpar – expression for matching right-parentheses; if passed as a str, then will be parsed as Suppress(rpar). If rpar is passed as an expression (such as Literal(')')), then it will be kept in the parsed results, and grouped with them. (default= Suppress(')'))

Example:

# simple example of four-function arithmetic with ints and
# variable names
integer = pyparsing_common.signed_integer
varname = pyparsing_common.identifier

arith_expr = infix_notation(integer | varname,
    [
    ('-', 1, OpAssoc.RIGHT),
    (one_of('* /'), 2, OpAssoc.LEFT),
    (one_of('+ -'), 2, OpAssoc.LEFT),
    ])

arith_expr.run_tests('''
    5+3*6
    (5+3)*6
    (5+x)*y
    -2--11
    ''', full_dump=False)

prints:

5+3*6
[[5, '+', [3, '*', 6]]]

(5+3)*6
[[[5, '+', 3], '*', 6]]

(5+x)*y
[[[5, '+', 'x'], '*', 'y']]

-2--11
[[['-', 2], '-', ['-', 11]]]

line(loc: int, strg: str) → str

Returns the line of text containing loc within a string, counting newlines as line separators.

lineno(loc: int, strg: str) → int

Returns current line number within a string, counting newlines as line separators. The first line is number 1.

Note - the default parsing behavior is to expand tabs in the input string before starting the parsing process. See ParserElement.parse_string() for more information on parsing strings containing <TAB> s, and suggested methods to maintain a consistent view of the parsed string, the parse location, and line and column positions within the parsed string.

locatedExpr(expr: ParserElement) → ParserElement

Deprecated since version 3.0.0: Use the Located class instead. Note that Located returns results with one less grouping level.

Helper to decorate a returned token with its starting and ending locations in the input string.

This helper adds the following results names:

• locn_start - location where matched expression begins

• locn_end - location where matched expression ends

• value - the actual parsed results

Be careful if the input text contains <TAB> characters, you may want to call ParserElement.parse_with_tabs()

makeHTMLTags(

tag_str: str | ParserElement,

) → tuple[ParserElement, ParserElement]

Deprecated since version 3.0.0: Use make_html_tags instead

makeXMLTags(

tag_str: str | ParserElement,

) → tuple[ParserElement, ParserElement]

Deprecated since version 3.0.0: Use make_xml_tags instead

make_html_tags(

tag_str: str | ParserElement,

) → tuple[ParserElement, ParserElement]

Helper to construct opening and closing tag expressions for HTML, given a tag name. Matches tags in either upper or lower case, attributes with namespaces and with quoted or unquoted values.

Example:

text = '<td>More info at the <a href="https://github.com/pyparsing/pyparsing/wiki">pyparsing</a> wiki page</td>'
# make_html_tags returns pyparsing expressions for the opening and
# closing tags as a 2-tuple
a, a_end = make_html_tags("A")
link_expr = a + SkipTo(a_end)("link_text") + a_end

for link in link_expr.search_string(text):
    # attributes in the <A> tag (like "href" shown here) are
    # also accessible as named results
    print(link.link_text, '->', link.href)

prints:

pyparsing -> https://github.com/pyparsing/pyparsing/wiki

make_xml_tags(

tag_str: str | ParserElement,

) → tuple[ParserElement, ParserElement]

Helper to construct opening and closing tag expressions for XML, given a tag name. Matches tags only in the given upper/lower case.

Example: similar to make_html_tags

matchOnlyAtCol(

n: int,

) → Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any]

Deprecated since version 3.0.0: Use match_only_at_col instead

matchPreviousExpr(expr: ParserElement) → ParserElement

Deprecated since version 3.0.0: Use match_previous_expr instead

matchPreviousLiteral(expr: ParserElement) → ParserElement

Deprecated since version 3.0.0: Use match_previous_literal instead

match_only_at_col(

n: int,

) → Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any]

Helper method for defining parse actions that require matching at a specific column in the input text.

match_previous_expr(expr: ParserElement) → ParserElement

Helper to define an expression that is indirectly defined from the tokens matched in a previous expression, that is, it looks for a ‘repeat’ of a previous expression. For example:

first = Word(nums)
second = match_previous_expr(first)
match_expr = first + ":" + second

will match "1:1", but not "1:2". Because this matches by expressions, will not match the leading "1:1" in "1:10"; the expressions are evaluated first, and then compared, so "1" is compared with "10". Do not use with packrat parsing enabled.

match_previous_literal(expr: ParserElement) → ParserElement

Helper to define an expression that is indirectly defined from the tokens matched in a previous expression, that is, it looks for a ‘repeat’ of a previous expression. For example:

.. testcode::

first = Word(nums) second = match_previous_literal(first) match_expr = first + “:” + second

will match "1:1", but not "1:2". Because this matches a previous literal, will also match the leading "1:1" in "1:10". If this is not desired, use match_previous_expr. Do not use with packrat parsing enabled.

nestedExpr(

opener: str | ParserElement = '(',

closer: str | ParserElement = ')',

content: ParserElement | None = None,

ignore_expr: ParserElement | None = _NO_IGNORE_EXPR_GIVEN,

**kwargs,

) → ParserElement

Deprecated since version 3.0.0: Use nested_expr instead

nested_expr(

opener: str | ParserElement = '(',

closer: str | ParserElement = ')',

content: ParserElement | None = None,

ignore_expr: ParserElement | None = _NO_IGNORE_EXPR_GIVEN,

**kwargs,

) → ParserElement

Helper method for defining nested lists enclosed in opening and closing delimiters ("(" and ")" are the default).

Parameters:

• opener – str - opening character for a nested list (default= "("); can also be a pyparsing expression

• closer – str - closing character for a nested list (default= ")"); can also be a pyparsing expression

• content – expression for items within the nested lists

• ignore_expr – expression for ignoring opening and closing delimiters (default = quoted_string)

Parameter ignoreExpr is retained for compatibility but will be removed in a future release.

If an expression is not provided for the content argument, the nested expression will capture all whitespace-delimited content between delimiters as a list of separate values.

Use the ignore_expr argument to define expressions that may contain opening or closing characters that should not be treated as opening or closing characters for nesting, such as quoted_string or a comment expression. Specify multiple expressions using an Or or MatchFirst. The default is quoted_string, but if no expressions are to be ignored, then pass None for this argument.

Example:

data_type = one_of("void int short long char float double")
decl_data_type = Combine(data_type + Opt(Word('*')))
ident = Word(alphas+'_', alphanums+'_')
number = pyparsing_common.number
arg = Group(decl_data_type + ident)
LPAR, RPAR = map(Suppress, "()")

code_body = nested_expr('{', '}', ignore_expr=(quoted_string | c_style_comment))

c_function = (decl_data_type("type")
              + ident("name")
              + LPAR + Opt(DelimitedList(arg), [])("args") + RPAR
              + code_body("body"))
c_function.ignore(c_style_comment)

source_code = '''
    int is_odd(int x) {
        return (x%2);
    }

    int dec_to_hex(char hchar) {
        if (hchar >= '0' && hchar <= '9') {
            return (ord(hchar)-ord('0'));
        } else {
            return (10+ord(hchar)-ord('A'));
        }
    }
'''
for func in c_function.search_string(source_code):
    print(f"{func.name} ({func.type}) args: {func.args}")

prints:

is_odd (int) args: [['int', 'x']]
dec_to_hex (int) args: [['char', 'hchar']]

nullDebugAction(*args)

Deprecated since version 3.0.0: Use null_debug_action instead

null_debug_action(*args)

‘Do-nothing’ debug action, to suppress debugging output during parsing.

oneOf(

strs: Iterable[str] | str,

caseless: bool = False,

use_regex: bool = True,

as_keyword: bool = False,

**kwargs,

) → ParserElement

Deprecated since version 3.0.0: Use one_of instead

one_of(

strs: Iterable[str] | str,

caseless: bool = False,

use_regex: bool = True,

as_keyword: bool = False,

**kwargs,

) → ParserElement

Helper to quickly define a set of alternative Literal s, and makes sure to do longest-first testing when there is a conflict, regardless of the input order, but returns a MatchFirst for best performance.

Parameters:

• strs – a string of space-delimited literals, or a collection of string literals

• caseless – treat all literals as caseless

• use_regex – bool - as an optimization, will generate a Regex object; otherwise, will generate a MatchFirst object (if caseless=True or as_keyword=True, or if creating a Regex raises an exception)

• as_keyword – bool - enforce Keyword-style matching on the generated expressions

Parameters asKeyword and useRegex are retained for pre-PEP8 compatibility, but will be removed in a future release.

Example:

comp_oper = one_of("< = > <= >= !=")
var = Word(alphas)
number = Word(nums)
term = var | number
comparison_expr = term + comp_oper + term
print(comparison_expr.search_string("B = 12  AA=23 B<=AA AA>12"))

prints:

[['B', '=', '12'], ['AA', '=', '23'], ['B', '<=', 'AA'], ['AA', '>', '12']]

opAssoc

alias of OpAssoc

originalTextFor(

expr: ParserElement,

as_string: bool = True,

**kwargs,

) → ParserElement

Deprecated since version 3.0.0: Use original_text_for instead

original_text_for(

expr: ParserElement,

as_string: bool = True,

**kwargs,

) → ParserElement

Helper to return the original, untokenized text for a given expression. Useful to restore the parsed fields of an HTML start tag into the raw tag text itself, or to revert separate tokens with intervening whitespace back to the original matching input text. By default, returns a string containing the original parsed text.

If the optional as_string argument is passed as False, then the return value is a ParseResults containing any results names that were originally matched, and a single token containing the original matched text from the input string. So if the expression passed to original_text_for contains expressions with defined results names, you must set as_string to False if you want to preserve those results name values.

The asString pre-PEP8 argument is retained for compatibility, but will be removed in a future release.

Example:

src = "this is test <b> bold <i>text</i> </b> normal text "
for tag in ("b", "i"):
    opener, closer = make_html_tags(tag)
    patt = original_text_for(opener + ... + closer)
    print(patt.search_string(src)[0])

prints:

['<b> bold <i>text</i> </b>']
['<i>text</i>']

class pyparsing_common

Bases: object

Here are some common low-level expressions that may be useful in jump-starting parser development:

• numeric forms (integers, reals, scientific notation)

• common programming identifiers

• network addresses (MAC, IPv4, IPv6)

• ISO8601 dates and datetime

• UUID

• comma-separated list

• url

Parse actions:

• convert_to_integer

• convert_to_float

• convert_to_date

• convert_to_datetime

• strip_html_tags

• upcase_tokens

• downcase_tokens

Examples:

pyparsing_common.number.run_tests('''
    # any int or real number, returned as the appropriate type
    100
    -100
    +100
    3.14159
    6.02e23
    1e-12
    ''')

# any int or real number, returned as the appropriate type
100
[100]

-100
[-100]

+100
[100]

3.14159
[3.14159]

6.02e23
[6.02e+23]

1e-12
[1e-12]

pyparsing_common.fnumber.run_tests('''
    # any int or real number, returned as float
    100
    -100
    +100
    3.14159
    6.02e23
    1e-12
    ''')

# any int or real number, returned as float
100
[100.0]

-100
[-100.0]

+100
[100.0]

3.14159
[3.14159]

6.02e23
[6.02e+23]

1e-12
[1e-12]

pyparsing_common.hex_integer.run_tests('''
    # hex numbers
    100
    FF
    ''')

# hex numbers
100
[256]

FF
[255]

pyparsing_common.fraction.run_tests('''
    # fractions
    1/2
    -3/4
    ''')

# fractions
1/2
[0.5]

-3/4
[-0.75]

pyparsing_common.mixed_integer.run_tests('''
    # mixed fractions
    1
    1/2
    -3/4
    1-3/4
    ''')

# mixed fractions
1
[1]

1/2
[0.5]

-3/4
[-0.75]

1-3/4
[1.75]

import uuid
pyparsing_common.uuid.set_parse_action(token_map(uuid.UUID))
pyparsing_common.uuid.run_tests('''
    # uuid
    12345678-1234-5678-1234-567812345678
    ''')

# uuid
12345678-1234-5678-1234-567812345678
[UUID('12345678-1234-5678-1234-567812345678')]

static as_datetime(s, l, t)

Parse action to convert parsed dates or datetimes to a Python datetime.datetime.

This parse action will use the year, month, day, etc. results names defined in the ISO8601 date expressions, but it can be used with any expression that provides one or more of these fields.

Omitted fields will default to fields from Jan 1, 00:00:00.

Invalid dates will raise a ParseException with the error message indicating the invalid date fields.

comma_separated_list = comma separated list

Predefined expression of 1 or more printable words or quoted strings, separated by commas.

static convertToDate(fmt: str = '%Y-%m-%d')

Deprecated since version 3.0.0: Use convert_to_date instead

static convertToDatetime(fmt: str = '%Y-%m-%dT%H:%M:%S.%f')

Deprecated since version 3.0.0: Use convert_to_datetime instead

static convertToFloat(_, __, t)

Deprecated since version 3.0.0: Use convert_to_float instead

static convertToInteger(_, __, t)

Deprecated since version 3.0.0: Use convert_to_integer instead

static convert_to_date(fmt: str = '%Y-%m-%d')

Helper to create a parse action for converting parsed date string to Python datetime.date

Params - - fmt - format to be passed to datetime.strptime (default= "%Y-%m-%d")

Example:

date_expr = pyparsing_common.iso8601_date.copy()
date_expr.set_parse_action(pyparsing_common.convert_to_date())
print(date_expr.parse_string("1999-12-31"))

prints:

[datetime.date(1999, 12, 31)]

static convert_to_datetime(fmt: str = '%Y-%m-%dT%H:%M:%S.%f')

Helper to create a parse action for converting parsed datetime string to Python datetime.datetime

Params - - fmt - format to be passed to datetime.strptime (default= "%Y-%m-%dT%H:%M:%S.%f")

Example:

dt_expr = pyparsing_common.iso8601_datetime.copy()
dt_expr.set_parse_action(pyparsing_common.convert_to_datetime())
print(dt_expr.parse_string("1999-12-31T23:59:59.999"))

prints:

[datetime.datetime(1999, 12, 31, 23, 59, 59, 999000)]

static convert_to_float(_, __, t)

Parse action for converting parsed numbers to Python float

static convert_to_integer(_, __, t)

Parse action for converting parsed integers to Python int

static downcaseTokens(s, l, t)

Deprecated since version 3.0.0: Use downcase_tokens instead

static downcase_tokens(s, l, t)

Parse action to convert tokens to lower case.

fnumber = fnumber

any int or real number, always converts to a float

fraction = fraction

fractional expression of an integer divided by an integer, converts to a float

hex_integer = hex integer

expression that parses a hexadecimal integer, converts to an int

identifier = identifier

typical code identifier (leading alpha or ‘_’, followed by 0 or more alphas, nums, or ‘_’)

ieee_float = ieee_float

any floating-point literal (int, real number, infinity, or NaN), converts to a float

integer = integer

expression that parses an unsigned integer, converts to an int

ipv4_address = IPv4 address

IPv4 address (0.0.0.0 - 255.255.255.255)

ipv6_address = IPv6 address

IPv6 address (long, short, or mixed form)

iso8601_date = ISO8601 date

ISO8601 date (yyyy-mm-dd)

iso8601_date_validated = ISO8601 date

Validated ISO8601 date strings, raising ParseException for invalid date values.

iso8601_datetime = ISO8601 datetime

ISO8601 datetime (yyyy-mm-ddThh:mm:ss.s(Z|+-00:00)) - trailing seconds, milliseconds, and timezone optional; accepts separating 'T' or ' '

iso8601_datetime_validated = ISO8601 datetime

Validated ISO8601 date and time strings, raising ParseException for invalid date/time values.

mac_address = MAC address

MAC address xx:xx:xx:xx:xx (may also have ‘-’ or ‘.’ delimiters)

mixed_integer = fraction or mixed integer-fraction

mixed integer of the form ‘integer - fraction’, with optional leading integer, converts to a float

number = number

any numeric expression, converts to the corresponding Python type

real = real number

expression that parses a floating point number, converts to a float

sci_real = real number with scientific notation

expression that parses a floating point number with optional scientific notation, converts to a float

signed_integer = signed integer

expression that parses an integer with optional leading sign, converts to an int

static stripHTMLTags(s: str, l: int, tokens: ParseResults)

Deprecated since version 3.0.0: Use strip_html_tags instead

static strip_html_tags(s: str, l: int, tokens: ParseResults)

Parse action to remove HTML tags from web page HTML source

Example:

# strip HTML links from normal text
text = '<td>More info at the <a href="https://github.com/pyparsing/pyparsing/wiki">pyparsing</a> wiki page</td>'
td, td_end = make_html_tags("TD")
table_text = td + SkipTo(td_end).set_parse_action(
    pyparsing_common.strip_html_tags)("body") + td_end
print(table_text.parse_string(text).body)

Prints:

More info at the pyparsing wiki page

static upcaseTokens(s, l, t)

Deprecated since version 3.0.0: Use upcase_tokens instead

static upcase_tokens(s, l, t)

Parse action to convert tokens to upper case.

url = url

URL (http/https/ftp scheme)

Changed in version 3.1.0: url named group added

uuid = UUID

UUID (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx)

class pyparsing_test

Bases: object

namespace class for classes useful in writing unit tests

class TestParseResultsAsserts(methodName='runTest')

Bases: TestCase

A mixin class to add parse results assertion methods to normal unittest.TestCase classes.

assertParseAndCheckDict(

expr,

test_string,

expected_dict,

msg=None,

verbose=True,

)

Convenience wrapper assert to test a parser element and input string, and assert that the resulting ParseResults.as_dict() is equal to the expected_dict.

assertParseAndCheckList(

expr,

test_string,

expected_list,

msg=None,

verbose=True,

)

Convenience wrapper assert to test a parser element and input string, and assert that the resulting ParseResults.as_list() is equal to the expected_list.

assertParseResultsEquals(

result,

expected_list=None,

expected_dict=None,

msg=None,

)

Unit test assertion to compare a ParseResults object with an optional expected_list, and compare any defined results names with an optional expected_dict.

assertRaisesParseException(

exc_type=ParseException,

expected_msg=None,

msg=None,

)

assertRunTestResults(

run_tests_report,

expected_parse_results=None,

msg=None,

)

Unit test assertion to evaluate output of run_tests().

If a list of list-dict tuples is given as the expected_parse_results argument, then these are zipped with the report tuples returned by run_tests() and evaluated using assertParseResultsEquals(). Finally, asserts that the overall :meth:~ParserElement.run_tests success value is True.

Parameters:

• run_tests_report (tuple[bool, list[tuple[str, ParseResults | Exception]]]) – the return value from ParserElement.run_tests()

• expected_parse_results (list[tuple[str | list | dict | Exception, ...]]) – (optional)

class reset_pyparsing_context

Bases: object

Context manager to be used when writing unit tests that modify pyparsing config values: - packrat parsing - bounded recursion parsing - default whitespace characters - default keyword characters - literal string auto-conversion class - __diag__ settings

Example:

ppt = pyparsing.pyparsing_test

class MyTestClass(ppt.TestParseResultsAsserts):
    def test_literal(self):
        with ppt.reset_pyparsing_context():
            # test that literals used to construct
            # a grammar are automatically suppressed
            ParserElement.inline_literals_using(Suppress)

            term = Word(alphas) | Word(nums)
            group = Group('(' + term[...] + ')')

            # assert that the '()' characters
            # are not included in the parsed tokens
            self.assertParseAndCheckList(
                group,
                "(abc 123 def)",
                ['abc', '123', 'def']
            )

        # after exiting context manager, literals
        # are converted to Literal expressions again

copy()

restore()

save()

static with_line_numbers(

s: str,

start_line: int | None = None,

end_line: int | None = None,

expand_tabs: bool = True,

eol_mark: str = '|',

mark_spaces: str | None = None,

mark_control: str | None = None,

*,

indent: str | int = '',

base_1: bool = True,

) → str

Helpful method for debugging a parser - prints a string with line and column numbers. (Line and column numbers are 1-based by default - if debugging a parse action, pass base_1=False, to correspond to the loc value passed to the parse action.)

Parameters:

• s – string to be printed with line and column numbers

• start_line – starting line number in s to print (default=1)

• end_line – ending line number in s to print (default=len(s))

• expand_tabs – expand tabs to spaces, to match the pyparsing default

• eol_mark – string to mark the end of lines, helps visualize trailing spaces

• mark_spaces – special character to display in place of spaces

• mark_control –

  convert non-printing control characters to a placeholding character; valid values:

  • "unicode" - replaces control chars with Unicode symbols, such as “␍” and “␊”

  • any single character string - replace control characters with given string

  • None (default) - string is displayed as-is

• indent – string to indent with line and column numbers; if an int is passed, converted to " " * indent

• base_1 – whether to label string using base 1; if False, string will be labeled based at 0

Returns:

input string with leading line numbers and column number headers

Changed in version 3.2.0: New indent and base_1 arguments.

class pyparsing_unicode

Bases: unicode_set

A namespace class for defining common language unicode_sets.

class Arabic

Bases: unicode_set

Unicode set for Arabic Unicode Character Range

BMP

alias of BasicMultilingualPlane

class BasicMultilingualPlane

Bases: unicode_set

Unicode set for the Basic Multilingual Plane

class CJK

Bases: Chinese, Japanese, Hangul

Unicode set for combined Chinese, Japanese, and Korean (CJK) Unicode Character Range

class Chinese

Bases: unicode_set

Unicode set for Chinese Unicode Character Range

class Cyrillic

Bases: unicode_set

Unicode set for Cyrillic Unicode Character Range

class Devanagari

Bases: unicode_set

Unicode set for Devanagari Unicode Character Range

class Greek

Bases: unicode_set

Unicode set for Greek Unicode Character Ranges

class Hangul

Bases: unicode_set

Unicode set for Hangul (Korean) Unicode Character Range

class Hebrew

Bases: unicode_set

Unicode set for Hebrew Unicode Character Range

class Japanese

Bases: unicode_set

Unicode set for Japanese Unicode Character Range, combining Kanji, Hiragana, and Katakana ranges

class Hiragana

Bases: unicode_set

Unicode set for Hiragana Unicode Character Range

class Kanji

Bases: unicode_set

Unicode set for Kanji Unicode Character Range

class Katakana

Bases: unicode_set

Unicode set for Katakana Unicode Character Range

ひらがな

alias of Hiragana

カタカナ

alias of Katakana

漢字

alias of Kanji

Korean

alias of Hangul

class Latin1

Bases: unicode_set

Unicode set for Latin-1 Unicode Character Range

class LatinA

Bases: unicode_set

Unicode set for Latin-A Unicode Character Range

class LatinB

Bases: unicode_set

Unicode set for Latin-B Unicode Character Range

class Thai

Bases: unicode_set

Unicode set for Thai Unicode Character Range

Ελληνικά

alias of Greek

кириллица

alias of Cyrillic

العربية

alias of Arabic

ไทย

alias of Thai

中文

alias of Chinese

日本語

alias of Japanese

한국어

alias of Hangul

removeQuotes(s: str, l: int, t: ParseResults) → Any

Deprecated since version 3.0.0: Use remove_quotes instead

remove_quotes(s: str, l: int, t: ParseResults) → Any

Helper parse action for removing quotation marks from parsed quoted strings, that use a single character for quoting. For parsing strings that may have multiple characters, use the QuotedString class.

Example:

>>> # by default, quotation marks are included in parsed results
>>> quoted_string.parse_string("'Now is the Winter of our Discontent'")
ParseResults(["'Now is the Winter of our Discontent'"], {})

>>> # use remove_quotes to strip quotation marks from parsed results
>>> dequoted = quoted_string().set_parse_action(remove_quotes)
>>> dequoted.parse_string("'Now is the Winter of our Discontent'")
ParseResults(['Now is the Winter of our Discontent'], {})

replaceHTMLEntity(s, l, t)

Deprecated since version 3.0.0: Use replace_html_entity instead

replaceWith(

repl_str: Any,

) → Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any]

Deprecated since version 3.0.0: Use replace_with instead

replace_html_entity(s, l, t)

Helper parser action to replace common HTML entities with their special characters

replace_with(

repl_str: Any,

) → Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any]

Helper method for common parse actions that simply return a literal value. Especially useful when used with transform_string().

Example:

>>> num = Word(nums).set_parse_action(lambda toks: int(toks[0]))
>>> na = one_of("N/A NA").set_parse_action(replace_with(math.nan))
>>> term = na | num

>>> term[1, ...].parse_string("324 234 N/A 234")
ParseResults([324, 234, nan, 234], {})

show_best_practices(file=sys.stdout) → str | None

Load and return the project’s best practices.

Example:

>>> import pyparsing as pp
>>> pp.show_best_practices()
<!--
This file contains instructions for best practices for developing parsers with pyparsing, and can be used by AI agents
when generating Python code using pyparsing.
-->
...

This can also be run from the command line:

python -m pyparsing.ai.show_best_practices

srange(s: str) → str

Helper to easily define string ranges for use in Word construction. Borrows syntax from regexp '[]' string range definitions:

srange("[0-9]")   -> "0123456789"
srange("[a-z]")   -> "abcdefghijklmnopqrstuvwxyz"
srange("[a-z$_]") -> "abcdefghijklmnopqrstuvwxyz$_"

The input string must be enclosed in []’s, and the returned string is the expanded character set joined into a single string. The values enclosed in the []’s may be:

• a single character

• an escaped character with a leading backslash (such as \- or \])

• an escaped hex character with a leading '\x' (\x21, which is a '!' character) (\0x## is also supported for backwards compatibility)

• an escaped octal character with a leading '\0' (\041, which is a '!' character)

• a range of any of the above, separated by a dash ('a-z', etc.)

• any combination of the above ('aeiouy', 'a-zA-Z0-9_$', etc.)

testing

alias of pyparsing_test

tokenMap(

func,

*args,

) → Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any]

Deprecated since version 3.0.0: Use token_map instead

token_map(

func,

*args,

) → Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any]

Helper to define a parse action by mapping a function to all elements of a ParseResults list. If any additional args are passed, they are forwarded to the given function as additional arguments after the token, as in hex_integer = Word(hexnums).set_parse_action(token_map(int, 16)), which will convert the parsed data to an integer using base 16.

Example (compare the last to example in ParserElement.transform_string:

hex_ints = Word(hexnums)[1, ...].set_parse_action(token_map(int, 16))
hex_ints.run_tests('''
    00 11 22 aa FF 0a 0d 1a
    ''')

upperword = Word(alphas).set_parse_action(token_map(str.upper))
upperword[1, ...].run_tests('''
    my kingdom for a horse
    ''')

wd = Word(alphas).set_parse_action(token_map(str.title))
wd[1, ...].set_parse_action(' '.join).run_tests('''
    now is the winter of our discontent made glorious summer by this sun of york
    ''')

prints:

00 11 22 aa FF 0a 0d 1a
[0, 17, 34, 170, 255, 10, 13, 26]

my kingdom for a horse
['MY', 'KINGDOM', 'FOR', 'A', 'HORSE']

now is the winter of our discontent made glorious summer by this sun of york
['Now Is The Winter Of Our Discontent Made Glorious Summer By This Sun Of York']

traceParseAction(

f: Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any],

) → Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any]

Deprecated since version 3.0.0: Use trace_parse_action instead

trace_parse_action(

f: Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any],

) → Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any]

Decorator for debugging parse actions.

When the parse action is called, this decorator will print ">> entering method-name(line:<current_source_line>, <parse_location>, <matched_tokens>)". When the parse action completes, the decorator will print "<<" followed by the returned value, or any exception that the parse action raised.

Example:

wd = Word(alphas)

@trace_parse_action
def remove_duplicate_chars(tokens):
    return ''.join(sorted(set(''.join(tokens))))

wds = wd[1, ...].set_parse_action(remove_duplicate_chars)
print(wds.parse_string("slkdjs sld sldd sdlf sdljf"))

prints:

>>entering remove_duplicate_chars(line: 'slkdjs sld sldd sdlf sdljf',
0, ParseResults(['slkdjs', 'sld', 'sldd', 'sdlf', 'sdljf'], {}))
<<leaving remove_duplicate_chars (ret: 'dfjkls')
['dfjkls']

Changed in version 3.1.0: Exception type added to output

ungroup(expr: ParserElement) → ParserElement

Helper to undo pyparsing’s default grouping of And expressions, even if all but one are non-empty.

unicode

alias of pyparsing_unicode

class unicode_set

Bases: object

A set of Unicode characters, for language-specific strings for alphas, nums, alphanums, and printables. A unicode_set is defined by a list of ranges in the Unicode character set, in a class attribute _ranges. Ranges can be specified using 2-tuples or a 1-tuple, such as:

_ranges = [
    (0x0020, 0x007e),
    (0x00a0, 0x00ff),
    (0x0100,),
    ]

Ranges are left- and right-inclusive. A 1-tuple of (x,) is treated as (x, x).

A unicode set can also be defined using multiple inheritance of other unicode sets:

class CJK(Chinese, Japanese, Korean):
    pass

alphanums = ''

alphas = ''

identbodychars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyzªµ·ºÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖØÙÚÛÜÝÞßàáâãäåæçèéêëìíîïðñòóôõöøùúûüýþÿ'

identchars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyzªµºÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖØÙÚÛÜÝÞßàáâãäåæçèéêëìíîïðñòóôõöøùúûüýþÿ'

identifier = W:(A-Z_a-zªµºÀ-Ö..., 0-9A-Z_a-zªµ·...)

nums = ''

printables = ''

withAttribute(

*args: tuple[str, str],

**attr_dict,

) → Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any]

Deprecated since version 3.0.0: Use with_attribute instead

withClass(

classname: str,

namespace: str = '',

) → Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any]

Deprecated since version 3.0.0: Use with_class instead

with_attribute(

*args: tuple[str, str],

**attr_dict,

) → Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any]

Helper to create a validating parse action to be used with start tags created with make_xml_tags or make_html_tags. Use with_attribute to qualify a starting tag with a required attribute value, to avoid false matches on common tags such as <TD> or <DIV>.

Call with_attribute with a series of attribute names and values. Specify the list of filter attributes names and values as:

• keyword arguments, as in (align="right"), or

• as an explicit dict with ** operator, when an attribute name is also a Python reserved word, as in **{"class":"Customer", "align":"right"}

• a list of name-value tuples, as in (("ns1:class", "Customer"), ("ns2:align", "right"))

For attribute names with a namespace prefix, you must use the second form. Attribute names are matched insensitive to upper/lower case.

If just testing for class (with or without a namespace), use with_class.

To verify that the attribute exists, but without specifying a value, pass with_attribute.ANY_VALUE as the value.

The next two examples use the following input data and tag parsers:

html = '''
    <div>
    Some text
    <div type="grid">1 4 0 1 0</div>
    <div type="graph">1,3 2,3 1,1</div>
    <div>this has no type</div>
    </div>
'''
div,div_end = make_html_tags("div")

Only match div tag having a type attribute with value “grid”:

div_grid = div().set_parse_action(with_attribute(type="grid"))
grid_expr = div_grid + SkipTo(div | div_end)("body")
for grid_header in grid_expr.search_string(html):
    print(grid_header.body)

prints:

1 4 0 1 0

Construct a match with any div tag having a type attribute, regardless of the value:

div_any_type = div().set_parse_action(
    with_attribute(type=with_attribute.ANY_VALUE)
)
div_expr = div_any_type + SkipTo(div | div_end)("body")
for div_header in div_expr.search_string(html):
    print(div_header.body)

prints:

1 4 0 1 0
1,3 2,3 1,1

with_class(

classname: str,

namespace: str = '',

) → Callable[[], Any] | Callable[[ParseResults], Any] | Callable[[int, ParseResults], Any] | Callable[[str, int, ParseResults], Any]

Simplified version of with_attribute() when matching on a div class - made difficult because class is a reserved word in Python.

Using similar input data to the with_attribute() examples:

html = '''
    <div>
    Some text
    <div class="grid">1 4 0 1 0</div>
    <div class="graph">1,3 2,3 1,1</div>
    <div>this &lt;div&gt; has no class</div>
    </div>
'''
div,div_end = make_html_tags("div")

Only match div tag having the “grid” class:

div_grid = div().set_parse_action(with_class("grid"))
grid_expr = div_grid + SkipTo(div | div_end)("body")
for grid_header in grid_expr.search_string(html):
    print(grid_header.body)

prints:

1 4 0 1 0

Construct a match with any div tag having a class attribute, regardless of the value:

div_any_type = div().set_parse_action(
    with_class(withAttribute.ANY_VALUE)
)
div_expr = div_any_type + SkipTo(div | div_end)("body")
for div_header in div_expr.search_string(html):
    print(div_header.body)

prints:

1 4 0 1 0
1,3 2,3 1,1

Module pyparsing.diagram

class AnnotatedItem(*args: Any, **kwargs: Any)

Bases: Group

Simple subclass of Group that creates an annotation label

class ConverterState(diagram_kwargs: dict | None = None)

Bases: object

Stores some state that persists between recursions into the element tree

diagram_kwargs: dict

Shared kwargs that are used to customize the construction of diagrams

diagrams: dict[int, EditablePartial[NamedDiagram]]

A dictionary mapping ParserElement IDs to subdiagrams generated from them

extract_into_diagram(el_id: int)

Used when we encounter the same token twice in the same tree. When this happens, we replace all instances of that token with a terminal, and create a new subdiagram for the token

generate_index() → int

Generate a number used to index a diagram

get(key, default=None)

index: int

The index of the next element. This is used for sorting

index_generator = count(1)

class EachItem(*args: Any, **kwargs: Any)

Bases: Group

Custom railroad item to compose a:

• railroad.Group containing a

  • railroad.OneOrMore containing a

    • railroad.Choice of the elements in the railroad.Each

with the group label indicating that all must be matched

all_label = '[ALL]'

class EditablePartial(func: Callable[[...], T], args: list, kwargs: dict)

Bases: Generic[T]

Acts like a functools.partial, but can be edited. In other words, it represents a type that hasn’t yet been constructed.

classmethod from_call(

func: Callable[[...], T],

*args,

**kwargs,

) → EditablePartial[T]

If you call this function in the same way that you would call the constructor, it will store the arguments as you expect. For example EditablePartial.from_call(Fraction, 1, 3)() == Fraction(1, 3)

property name

class ElementState(

element: ParserElement,

converted: EditablePartial,

parent: EditablePartial,

number: int,

name: str = None,

parent_index: int | None = None,

extract: bool = False,

complete: bool = False,

)

Bases: object

State recorded for an individual pyparsing Element

complete: bool = False

If true, all of this element’s children have been filled out

converted: EditablePartial

The output Railroad element in an unconverted state

element: ParserElement

The pyparsing element that this represents

extract: bool = False

If true, we should extract this out into a subdiagram

mark_for_extraction(

el_id: int,

state: ConverterState,

name: str = None,

force: bool = False,

)

Called when this instance has been seen twice, and thus should eventually be extracted into a sub-diagram :param el_id: id of the element :param state: element/diagram state tracker :param name: name to use for this element’s text :param force: If true, force extraction now, regardless of the state of this. Only useful for extracting the root element when we know we’re finished

name: str = None

The name of the element

number: int

The order in which we found this element, used for sorting diagrams if this is extracted into a diagram

parent: EditablePartial

The parent Railroad element, which we store so that we can extract this if it’s duplicated

parent_index: int | None = None

The index of this inside its parent

class NamedDiagram(name: str, index: int, diagram: railroad.DiagramItem = None)

Bases: object

A simple structure for associating a name with a railroad diagram

property bookmark

diagram: railroad.DiagramItem = None

index: int

name: str

railroad_to_html(diagrams: list[NamedDiagram], embed=False, **kwargs) → str

Given a list of NamedDiagram, produce a single HTML string that visualises those diagrams.

Params kwargs:

kwargs to be passed in to the template

resolve_partial(

partial: EditablePartial[T],

) → T

Recursively resolves a collection of Partials into whatever type they are

to_railroad(

element: ParserElement,

diagram_kwargs: dict | None = None,

vertical: int = 3,

show_results_names: bool = False,

show_groups: bool = False,

show_hidden: bool = False,

) → list[NamedDiagram]

Convert a pyparsing element tree into a list of diagrams. This is the recommended entrypoint to diagram creation if you want to access the Railroad tree before it is converted to HTML

Parameters:

• element – base element of the parser being diagrammed

• diagram_kwargs – kwargs to pass to the Diagram() constructor

• vertical – (optional) int - limit at which number of alternatives should be shown vertically instead of horizontally

• show_results_names – bool to indicate whether results name annotations should be included in the diagram

• show_groups – bool to indicate whether groups should be highlighted with an unlabeled surrounding box

• show_hidden – bool to indicate whether internal elements that are typically hidden should be shown