gavo.imp.pyparsing module

pyparsing module - Classes and methods to define and execute parsing grammars

The pyparsing module 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.parseString(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.parseString 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.setResultsName

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

• find some helpful expression short-cuts like delimitedList and oneOf

• find more useful common expressions in the pyparsing_common namespace class

class gavo.imp.pyparsing.And(exprs, savelist=True)

Bases: ParseExpression

Requires all given ParseExpression 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 = OneOrMore(Word(alphas))

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

checkRecursion(parseElementList)

parseImpl(instring, loc, doActions=True)

streamline()

class gavo.imp.pyparsing.CaselessKeyword(matchString, identChars=None)

Bases: Keyword

Caseless version of Keyword.

Example:

OneOrMore(CaselessKeyword("CMD")).parseString("cmd CMD Cmd10") # -> ['CMD', 'CMD']

(Contrast with example for CaselessLiteral.)

class gavo.imp.pyparsing.CaselessLiteral(matchString)

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:

OneOrMore(CaselessLiteral("CMD")).parseString("cmd CMD Cmd10") # -> ['CMD', 'CMD', 'CMD']

(Contrast with example for CaselessKeyword.)

parseImpl(instring, loc, doActions=True)

class gavo.imp.pyparsing.Char(charset, asKeyword=False, excludeChars=None)

Bases: _WordRegex

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

class gavo.imp.pyparsing.CharsNotIn(notChars, min=1, max=0, exact=0)

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).parseString("dkls,lsdkjf,s12 34,@!#,213"))

prints:

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

parseImpl(instring, loc, doActions=True)

class gavo.imp.pyparsing.CloseMatch(match_string, maxMismatches=1)

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

• maxMismatches - (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.parseString("ATCATCGAAXGGA") # -> (['ATCATCGAAXGGA'], {'mismatches': [[9]], 'original': ['ATCATCGAATGGA']})
patt.parseString("ATCAXCGAAXGGA") # -> Exception: Expected 'ATCATCGAATGGA' (with up to 1 mismatches) (at char 0), (line:1, col:1)

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

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

parseImpl(instring, loc, doActions=True)

class gavo.imp.pyparsing.Combine(expr, joinString='', adjacent=True)

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.parseString('3.1416')) # -> ['3', '.', '1416']
# will also erroneously match the following
print(real.parseString('3. 1416')) # -> ['3', '.', '1416']

real = Combine(Word(nums) + '.' + Word(nums))
print(real.parseString('3.1416')) # -> ['3.1416']
# no match when there are internal spaces
print(real.parseString('3. 1416')) # -> Exception: Expected W:(0123...)

ignore(other)

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 = OneOrMore(Word(alphas))
patt.parseString('ablaj /* comment */ lskjd') # -> ['ablaj']

patt.ignore(cStyleComment)
patt.parseString('ablaj /* comment */ lskjd') # -> ['ablaj', 'lskjd']

postParse(instring, loc, tokenlist)

class gavo.imp.pyparsing.Dict(expr)

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.

Example:

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

text = "shape: SQUARE posn: upper left color: light blue texture: burlap"
attr_expr = (label + Suppress(':') + OneOrMore(data_word, stopOn=label).setParseAction(' '.join))

# print attributes as plain groups
print(OneOrMore(attr_expr).parseString(text).dump())

# instead of OneOrMore(expr), parse using Dict(OneOrMore(Group(expr))) - Dict will auto-assign names
result = Dict(OneOrMore(Group(attr_expr))).parseString(text)
print(result.dump())

# access named fields as dict entries, or output as dict
print(result['shape'])
print(result.asDict())

prints:

['shape', 'SQUARE', 'posn', 'upper left', 'color', 'light blue', 'texture', 'burlap']
[['shape', 'SQUARE'], ['posn', 'upper left'], ['color', 'light blue'], ['texture', 'burlap']]
- color: light blue
- posn: upper left
- shape: SQUARE
- texture: burlap
SQUARE
{'color': 'light blue', 'posn': 'upper left', 'texture': 'burlap', 'shape': 'SQUARE'}

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

postParse(instring, loc, tokenlist)

class gavo.imp.pyparsing.Each(exprs, savelist=True)

Bases: ParseExpression

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

May be constructed using the '&' operator.

Example:

color = oneOf("RED ORANGE YELLOW GREEN BLUE PURPLE BLACK WHITE BROWN")
shape_type = oneOf("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 & Optional(color_attr) & Optional(size_attr)

shape_spec.runTests('''
    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

checkRecursion(parseElementList)

parseImpl(instring, loc, doActions=True)

streamline()

class gavo.imp.pyparsing.Empty

Bases: Token

An empty token, will always match.

class gavo.imp.pyparsing.FollowedBy(expr)

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, stopOn=label).setParseAction(' '.join))

OneOrMore(attr_expr).parseString("shape: SQUARE color: BLACK posn: upper left").pprint()

prints:

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

parseImpl(instring, loc, doActions=True)

class gavo.imp.pyparsing.Forward(other=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 variable using the ‘<<’ operator.

Note: take care when assigning to Forward not to overlook precedence of operators.

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

fwdExpr << a | b | c

will actually be evaluated as:

(fwdExpr << 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:

fwdExpr << (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.

copy()

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).setParseAction(lambda toks: int(toks[0]))
integerK = integer.copy().addParseAction(lambda toks: toks[0] * 1024) + Suppress("K")
integerM = integer.copy().addParseAction(lambda toks: toks[0] * 1024 * 1024) + Suppress("M")

print(OneOrMore(integerK | integerM | integer).parseString("5K 100 640K 256M"))

prints:

[5120, 100, 655360, 268435456]

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

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

leaveWhitespace()

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.

streamline()

validate(validateTrace=None)

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

class gavo.imp.pyparsing.GoToColumn(colno)

Bases: _PositionToken

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

parseImpl(instring, loc, doActions=True)

preParse(instring, loc)

class gavo.imp.pyparsing.Group(expr)

Bases: TokenConverter

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

Example:

ident = Word(alphas)
num = Word(nums)
term = ident | num
func = ident + Optional(delimitedList(term))
print(func.parseString("fn a, b, 100"))  # -> ['fn', 'a', 'b', '100']

func = ident + Group(Optional(delimitedList(term)))
print(func.parseString("fn a, b, 100"))  # -> ['fn', ['a', 'b', '100']]

postParse(instring, loc, tokenlist)

class gavo.imp.pyparsing.Keyword(matchString, identChars=None, caseless=False)

Bases: Token

Token to exactly match a specified string as a keyword, that is, it must be immediately followed by a non-keyword character. 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:

• identChars 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").parseString("start")  # -> ['start']
Keyword("start").parseString("starting")  # -> Exception

For case-insensitive matching, use CaselessKeyword.

DEFAULT_KEYWORD_CHARS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_$'

copy()

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).setParseAction(lambda toks: int(toks[0]))
integerK = integer.copy().addParseAction(lambda toks: toks[0] * 1024) + Suppress("K")
integerM = integer.copy().addParseAction(lambda toks: toks[0] * 1024 * 1024) + Suppress("M")

print(OneOrMore(integerK | integerM | integer).parseString("5K 100 640K 256M"))

prints:

[5120, 100, 655360, 268435456]

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

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

parseImpl(instring, loc, doActions=True)

static setDefaultKeywordChars(chars)

Overrides the default Keyword chars

class gavo.imp.pyparsing.LineEnd

Bases: _PositionToken

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

parseImpl(instring, loc, doActions=True)

class gavo.imp.pyparsing.LineStart

Bases: _PositionToken

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

Example:

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

for t in (LineStart() + 'AAA' + restOfLine).searchString(test):
    print(t)

prints:

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

parseImpl(instring, loc, doActions=True)

class gavo.imp.pyparsing.Literal(matchString)

Bases: Token

Token to exactly match a specified string.

Example:

Literal('blah').parseString('blah')  # -> ['blah']
Literal('blah').parseString('blahfooblah')  # -> ['blah']
Literal('blah').parseString('bla')  # -> Exception: Expected "blah"

For case-insensitive matching, use CaselessLiteral.

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

parseImpl(instring, loc, doActions=True)

class gavo.imp.pyparsing.MatchFirst(exprs, savelist=False)

Bases: ParseExpression

Requires that at least one ParseExpression is found. If two expressions match, 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.searchString("123 3.1416 789")) #  Fail! -> [['123'], ['3'], ['1416'], ['789']]

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

checkRecursion(parseElementList)

parseImpl(instring, loc, doActions=True)

streamline()

class gavo.imp.pyparsing.NoMatch

Bases: Token

A token that will never match.

parseImpl(instring, loc, doActions=True)

class gavo.imp.pyparsing.NotAny(expr)

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 = Optional(NOT) + ident

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

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

parseImpl(instring, loc, doActions=True)

class gavo.imp.pyparsing.OneOrMore(expr, stopOn=None)

Bases: _MultipleMatch

Repetition of one or more of the given expression.

Parameters:

• expr - expression that must match one or more times

• stopOn - (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).setParseAction(' '.join))

text = "shape: SQUARE posn: upper left color: BLACK"
OneOrMore(attr_expr).parseString(text).pprint()  # Fail! read 'color' as data instead of next label -> [['shape', 'SQUARE color']]

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

# could also be written as
(attr_expr * (1,)).parseString(text).pprint()

class gavo.imp.pyparsing.OnlyOnce(methodCall)

Bases: object

Wrapper for parse actions, to ensure they are only called once.

reset()

class gavo.imp.pyparsing.Optional(expr, default=<gavo.imp.pyparsing._NullToken object>)

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) + Optional('-' + Word(nums, exact=4)))
zip.runTests('''
    # 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-
     ^
FAIL: Expected end of text (at char 5), (line:1, col:6)

parseImpl(instring, loc, doActions=True)

class gavo.imp.pyparsing.Or(exprs, savelist=False)

Bases: ParseExpression

Requires that at least one ParseExpression 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.searchString("123 3.1416 789"))

prints:

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

checkRecursion(parseElementList)

parseImpl(instring, loc, doActions=True)

streamline()

exception gavo.imp.pyparsing.ParseBaseException(pstr, loc=0, msg=None, elem=None)

Bases: Exception

base exception class for all parsing runtime exceptions

markInputline(markerString='>!<')

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

class gavo.imp.pyparsing.ParseElementEnhance(expr, savelist=False)

Bases: ParserElement

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

checkRecursion(parseElementList)

ignore(other)

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 = OneOrMore(Word(alphas))
patt.parseString('ablaj /* comment */ lskjd') # -> ['ablaj']

patt.ignore(cStyleComment)
patt.parseString('ablaj /* comment */ lskjd') # -> ['ablaj', 'lskjd']

leaveWhitespace()

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.

parseImpl(instring, loc, doActions=True)

streamline()

validate(validateTrace=None)

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

exception gavo.imp.pyparsing.ParseException(pstr, loc=0, msg=None, elem=None)

Bases: ParseBaseException

Exception thrown when parse expressions don’t match class; supported attributes by name are: - lineno - returns the line number of the exception text - col - returns the column number of the exception text - line - returns the line containing the exception text

Example:

try:
    Word(nums).setName("integer").parseString("ABC")
except ParseException as pe:
    print(pe)
    print("column: {}".format(pe.col))

prints:

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

static explain(exc, depth=16)

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.

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

explain() is only supported under Python 3.

class gavo.imp.pyparsing.ParseExpression(exprs, savelist=False)

Bases: ParserElement

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

append(other)

copy()

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).setParseAction(lambda toks: int(toks[0]))
integerK = integer.copy().addParseAction(lambda toks: toks[0] * 1024) + Suppress("K")
integerM = integer.copy().addParseAction(lambda toks: toks[0] * 1024 * 1024) + Suppress("M")

print(OneOrMore(integerK | integerM | integer).parseString("5K 100 640K 256M"))

prints:

[5120, 100, 655360, 268435456]

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

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

ignore(other)

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 = OneOrMore(Word(alphas))
patt.parseString('ablaj /* comment */ lskjd') # -> ['ablaj']

patt.ignore(cStyleComment)
patt.parseString('ablaj /* comment */ lskjd') # -> ['ablaj', 'lskjd']

leaveWhitespace()

Extends leaveWhitespace defined in base class, and also invokes leaveWhitespace on all contained expressions.

streamline()

validate(validateTrace=None)

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

exception gavo.imp.pyparsing.ParseFatalException(pstr, loc=0, msg=None, elem=None)

Bases: ParseBaseException

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

class gavo.imp.pyparsing.ParseResults(toklist=None, name=None, asList=True, modal=True)

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.<resultsName> - see ParserElement.setResultsName)

Example:

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

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

def test(s, fn=repr):
    print("%s -> %s" % (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

append(item)

Add single element to end of ParseResults list of elements.

Example:

print(OneOrMore(Word(nums)).parseString("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)))
print(OneOrMore(Word(nums)).addParseAction(append_sum).parseString("0 123 321")) # -> ['0', '123', '321', 444]

asDict()

Returns the named parse results as a nested dictionary.

Example:

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

result = date_str.parseString('12/31/1999')
print(type(result), repr(result)) # -> <class 'pyparsing.ParseResults'> (['12', '/', '31', '/', '1999'], {'day': [('1999', 4)], 'year': [('12', 0)], 'month': [('31', 2)]})

result_dict = result.asDict()
print(type(result_dict), repr(result_dict)) # -> <class 'dict'> {'day': '1999', 'year': '12', 'month': '31'}

# even though a ParseResults supports dict-like access, sometime you just need to have a dict
import json
print(json.dumps(result)) # -> Exception: TypeError: ... is not JSON serializable
print(json.dumps(result.asDict())) # -> {"month": "31", "day": "1999", "year": "12"}

asList()

Returns the parse results as a nested list of matching tokens, all converted to strings.

Example:

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

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

asXML(doctag=None, namedItemsOnly=False, indent='', formatted=True)

(Deprecated) Returns the parse results as XML. Tags are created for tokens and lists that have defined results names.

clear()

Clear all elements and results names.

copy()

Returns a new copy of a ParseResults object.

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

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.parseString('12/31/1999')
print(result.dump())

prints:

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

extend(itemseq)

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

Example:

patt = OneOrMore(Word(alphas))

# 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)
print(patt.addParseAction(make_palindrome).parseString("lskdj sdlkjf lksd")) # -> 'lskdjsdlkjflksddsklfjkldsjdksl'

classmethod from_dict(other, name=None)

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, defaultValue=None)

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

Similar to dict.get().

Example:

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

result = date_str.parseString("1999/12/31")
print(result.get("year")) # -> '1999'
print(result.get("hour", "not specified")) # -> 'not specified'
print(result.get("hour")) # -> None

getName()

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 = OneOrMore(user_data)

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

prints:

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

haskeys()

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

insert(index, insStr)

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

Similar to list.insert().

Example:

print(OneOrMore(Word(nums)).parseString("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)
print(OneOrMore(Word(nums)).addParseAction(insert_locn).parseString("0 123 321")) # -> [0, '0', '123', '321']

items()

Returns an iterator of all named result key-value tuples.

iteritems

Returns an iterator of all named result key-value tuples (Python 2.x only).

iterkeys

Returns an iterator of all named result keys (Python 2.x only).

itervalues

Returns an iterator of all named result values (Python 2.x only).

keys()

Returns an iterator of all named result 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:

def remove_first(tokens):
    tokens.pop(0)
print(OneOrMore(Word(nums)).parseString("0 123 321")) # -> ['0', '123', '321']
print(OneOrMore(Word(nums)).addParseAction(remove_first).parseString("0 123 321")) # -> ['123', '321']

label = Word(alphas)
patt = label("LABEL") + OneOrMore(Word(nums))
print(patt.parseString("AAB 123 321").dump())

# 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.addParseAction(remove_LABEL)
print(patt.parseString("AAB 123 321").dump())

prints:

['AAB', '123', '321']
- LABEL: AAB

['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.parseString("fna a,b,(fnb c,d,200),100")
result.pprint(width=40)

prints:

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

values()

Returns an iterator of all named result values.

exception gavo.imp.pyparsing.ParseSyntaxException(pstr, loc=0, msg=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.

class gavo.imp.pyparsing.ParserElement(savelist=False)

Bases: object

Abstract base level parser element class.

DEFAULT_WHITE_CHARS = ' \n\t\r'

addCondition(*fns, **kwargs)

Add a boolean predicate function to expression’s list of parse actions. See setParseAction for function call signatures. Unlike setParseAction, functions passed to addCondition 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

Example:

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

result = date_str.parseString("1999/12/31")  # -> Exception: Only support years 2000 and later (at char 0), (line:1, col:1)

addParseAction(*fns, **kwargs)

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

See examples in copy.

canParseNext(instring, loc)

checkRecursion(parseElementList)

copy()

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).setParseAction(lambda toks: int(toks[0]))
integerK = integer.copy().addParseAction(lambda toks: toks[0] * 1024) + Suppress("K")
integerM = integer.copy().addParseAction(lambda toks: toks[0] * 1024 * 1024) + Suppress("M")

print(OneOrMore(integerK | integerM | integer).parseString("5K 100 640K 256M"))

prints:

[5120, 100, 655360, 268435456]

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

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

static enablePackrat(cache_size_limit=128)

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.enablePackrat. For best results, call enablePackrat() immediately after importing pyparsing.

Example:

import pyparsing
pyparsing.ParserElement.enablePackrat()

ignore(other)

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 = OneOrMore(Word(alphas))
patt.parseString('ablaj /* comment */ lskjd') # -> ['ablaj']

patt.ignore(cStyleComment)
patt.parseString('ablaj /* comment */ lskjd') # -> ['ablaj', 'lskjd']

static inlineLiteralsUsing(cls)

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.parseString("1999/12/31")  # -> ['1999', '/', '12', '/', '31']


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

date_str.parseString("1999/12/31")  # -> ['1999', '12', '31']

leaveWhitespace()

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.

matches(testString, parseAll=True)

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:

• testString - to test against this expression for a match

• parseAll - (default= True) - flag to pass to parseString when running tests

Example:

expr = Word(nums)
assert expr.matches("100")

packrat_cache = {}

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

packrat_cache_stats = [0, 0]

parseFile(file_or_filename, parseAll=False)

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.

parseImpl(instring, loc, doActions=True)

parseString(instring, parseAll=False)

Execute the parse expression with the given string. This is the main interface to the client code, once the complete expression has been built.

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

If you want the grammar to require that the entire input string be successfully parsed, then set parseAll to True (equivalent to ending the grammar with StringEnd()).

Note: parseString implicitly calls expandtabs() on the input string, in order to report proper column numbers in parse actions. If the input string contains tabs and the grammar uses parse actions that use the loc argument to index into the string being parsed, you can ensure you have a consistent view of the input string by:

• calling parseWithTabs on your grammar before calling parseString (see parseWithTabs)

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

• explicitly expand the tabs in your input string before calling parseString

Example:

Word('a').parseString('aaaaabaaa')  # -> ['aaaaa']
Word('a').parseString('aaaaabaaa', parseAll=True)  # -> Exception: Expected end of text

parseWithTabs()

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

postParse(instring, loc, tokenlist)

preParse(instring, loc)

static resetCache()

runTests(tests, parseAll=True, comment='#', fullDump=True, printResults=True, failureTests=False, postParse=None, file=None)

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

• parseAll - (default= True) - flag to pass to parseString when running tests

• comment - (default= '#') - expression for indicating embedded comments in the test

  string; pass None to disable comment filtering

• fullDump - (default= True) - dump results as list followed by results names in nested outline;

  if False, only dump nested list

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

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

• postParse - (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

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

Example:

number_expr = pyparsing_common.number.copy()

result = number_expr.runTests('''
    # unsigned integer
    100
    # negative integer
    -100
    # float with scientific notation
    6.02e23
    # integer with scientific notation
    1e-12
    ''')
print("Success" if result[0] else "Failed!")

result = number_expr.runTests('''
    # stray character
    100Z
    # missing leading digit before '.'
    -.100
    # too many '.'
    3.14.159
    ''', failureTests=True)
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]

Success

# stray character
100Z
   ^
FAIL: Expected end of text (at char 3), (line:1, col:4)

# missing leading digit before '.'
-.100
^
FAIL: Expected {real number with scientific notation | real number | signed integer} (at char 0), (line:1, col:1)

# too many '.'
3.14.159
    ^
FAIL: Expected end of text (at char 4), (line:1, col:5)

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.runTest(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, maxMatches=2147483647, overlap=False)

Scan the input string for expression matches. Each match will return the matching tokens, start location, and end location. May be called with optional maxMatches 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 parseString for more information on parsing strings with embedded tabs.

Example:

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

prints:

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

searchString(instring, maxMatches=2147483647)

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

Example:

# 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.searchString("More than Iron, more than Lead, more than Gold I need Electricity"))

# the sum() builtin can be used to merge results into a single ParseResults object
print(sum(cap_word.searchString("More than Iron, more than Lead, more than Gold I need Electricity")))

prints:

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

setBreak(breakFlag=True)

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

setDebug(flag=True)

Enable display of debugging messages while doing pattern matching. Set flag to True to enable, False to disable.

Example:

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

# turn on debugging for wd
wd.setDebug()

OneOrMore(term).parseString("abc 123 xyz 890")

prints:

Match alphaword at loc 0(1,1)
Matched alphaword -> ['abc']
Match alphaword at loc 3(1,4)
Exception raised:Expected alphaword (at char 4), (line:1, col:5)
Match alphaword at loc 7(1,8)
Matched alphaword -> ['xyz']
Match alphaword at loc 11(1,12)
Exception raised:Expected alphaword (at char 12), (line:1, col:13)
Match alphaword at loc 15(1,16)
Exception raised:Expected alphaword (at char 15), (line:1, col:16)

The output shown is that produced by the default debug actions - custom debug actions can be specified using setDebugActions. 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 setName 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 setName is "W:(ABCD...)".

setDebugActions(startAction, successAction, exceptionAction)

Enable display of debugging messages while doing pattern matching.

static setDefaultWhitespaceChars(chars)

Overrides the default whitespace chars

Example:

# default whitespace chars are space, <TAB> and newline
OneOrMore(Word(alphas)).parseString("abc def\nghi jkl")  # -> ['abc', 'def', 'ghi', 'jkl']

# change to just treat newline as significant
ParserElement.setDefaultWhitespaceChars(" \t")
OneOrMore(Word(alphas)).parseString("abc def\nghi jkl")  # -> ['abc', 'def']

setFailAction(fn)

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.

setName(name)

Define name for this expression, makes debugging and exception messages clearer.

Example:

Word(nums).parseString("ABC")  # -> Exception: Expected W:(0123...) (at char 0), (line:1, col:1)
Word(nums).setName("integer").parseString("ABC")  # -> Exception: Expected integer (at char 0), (line:1, col:1)

setParseAction(*fns, **kwargs)

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

If the functions in fns modify the tokens, they can return them as the return value from fn, and the modified list of tokens will replace the original. Otherwise, fn does not need to return any value.

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

Optional keyword arguments: - callDuringTry = (default= False) indicate if parse action should be run during lookaheads and alternate testing

Note: the default parsing behavior is to expand tabs in the input string before starting the parsing process. See parseString 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:

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

date_str.parseString("1999/12/31")  # -> ['1999', '/', '12', '/', '31']

# use parse action to convert to ints at parse time
integer = Word(nums).setParseAction(lambda toks: int(toks[0]))
date_str = integer + '/' + integer + '/' + integer

# note that integer fields are now ints, not strings
date_str.parseString("1999/12/31")  # -> [1999, '/', 12, '/', 31]

setResultsName(name, listAllMatches=False)

Define name for referencing matching tokens as a nested attribute of the returned parse results. NOTE: this 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.setResultsName("name") - see __call__.

Example:

date_str = (integer.setResultsName("year") + '/'
            + integer.setResultsName("month") + '/'
            + integer.setResultsName("day"))

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

setWhitespaceChars(chars)

Overrides the default whitespace chars

split(instring, maxsplit=2147483647, includeSeparators=False)

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 includeSeparators argument (default= False), if the separating matching text should be included in the split results.

Example:

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

prints:

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

streamline()

suppress()

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

transformString(instring)

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

Example:

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

print(wd.transformString("now is the winter of our discontent made glorious summer by this sun of york."))

prints:

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

tryParse(instring, loc)

validate(validateTrace=None)

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

verbose_stacktrace = False

class gavo.imp.pyparsing.PrecededBy(expr, retreat=None)

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

parseImpl(instring, loc=0, doActions=True)

class gavo.imp.pyparsing.QuotedString(quoteChar, escChar=None, escQuote=None, multiline=False, unquoteResults=True, endQuoteChar=None, convertWhitespaceEscapes=True)

Bases: Token

Token for matching strings that are delimited by quoting characters.

Defined with the following parameters:

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

• escChar - character to escape quotes, typically backslash (default= None)

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

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

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

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

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

Example:

qs = QuotedString('"')
print(qs.searchString('lsjdf "This is the quote" sldjf'))
complex_qs = QuotedString('{{', endQuoteChar='}}')
print(complex_qs.searchString('lsjdf {{This is the "quote"}} sldjf'))
sql_qs = QuotedString('"', escQuote='""')
print(sql_qs.searchString('lsjdf "This is the quote with ""embedded"" quotes" sldjf'))

prints:

[['This is the quote']]
[['This is the "quote"']]
[['This is the quote with "embedded" quotes']]

parseImpl(instring, loc, doActions=True)

exception gavo.imp.pyparsing.RecursiveGrammarException(parseElementList)

Bases: Exception

exception thrown by ParserElement.validate if the grammar could be improperly recursive

class gavo.imp.pyparsing.Regex(pattern, flags=0, asGroupList=False, asMatch=False)

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 parse results.

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

Example:

realnum = Regex(r"[+-]?\d+\.\d*")
date = Regex(r'(?P<year>\d{4})-(?P<month>\d\d?)-(?P<day>\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})")

# use regex module instead of stdlib re module to construct a Regex using
# a compiled regular expression
import regex
parser = pp.Regex(regex.compile(r'[0-9]'))

parseImpl(instring, loc, doActions=True)

parseImplAsGroupList(instring, loc, doActions=True)

parseImplAsMatch(instring, loc, doActions=True)

sub(repl)

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.transformString("h1:main title:"))
# prints "<h1>main title</h1>"

class gavo.imp.pyparsing.SkipTo(other, include=False, ignore=None, failOn=None)

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 - (default= False) if True, the target expression is also parsed

  (the skipped text and target expression are returned as a 2-element list).

• ignore - (default= None) used to define grammars (typically quoted strings and

  comments) that might contain false matches to the target expression

• failOn - (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=quotedString)
string_data.setParseAction(tokenMap(str.strip))
ticket_expr = (integer("issue_num") + SEP
              + string_data("sev") + SEP
              + string_data("desc") + SEP
              + integer("days_open"))

for tkt in ticket_expr.searchString(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

parseImpl(instring, loc, doActions=True)

class gavo.imp.pyparsing.StringEnd

Bases: _PositionToken

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

parseImpl(instring, loc, doActions=True)

class gavo.imp.pyparsing.StringStart

Bases: _PositionToken

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

parseImpl(instring, loc, doActions=True)

class gavo.imp.pyparsing.Suppress(expr, savelist=False)

Bases: TokenConverter

Converter for ignoring the results of a parsed expression.

Example:

source = "a, b, c,d"
wd = Word(alphas)
wd_list1 = wd + ZeroOrMore(',' + wd)
print(wd_list1.parseString(source))

# 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 + ZeroOrMore(Suppress(',') + wd)
print(wd_list2.parseString(source))

prints:

['a', ',', 'b', ',', 'c', ',', 'd']
['a', 'b', 'c', 'd']

(See also delimitedList.)

postParse(instring, loc, tokenlist)

suppress()

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

class gavo.imp.pyparsing.Token

Bases: ParserElement

Abstract ParserElement subclass, for defining atomic matching patterns.

class gavo.imp.pyparsing.TokenConverter(expr, savelist=False)

Bases: ParseElementEnhance

Abstract subclass of ParseExpression, for converting parsed results.

class gavo.imp.pyparsing.White(ws=' \t\r\n', min=1, max=0, exact=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.

parseImpl(instring, loc, doActions=True)

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 gavo.imp.pyparsing.Word(initChars, bodyChars=None, min=1, max=0, exact=0, asKeyword=False, excludeChars=None)

Bases: Token

Token for matching words composed of allowed character sets. Defined with string containing all allowed initial characters, an optional string containing allowed body characters (if omitted, defaults to the initial character set), 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. An optional excludeChars parameter can list characters that might be found in the input bodyChars string; useful to define a word of all printables except for one or two characters, for instance.

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)

Example:

# a word composed of digits
integer = Word(nums) # equivalent to Word("0123456789") or Word(srange("0-9"))

# a word with a leading capital, and zero or more lowercase
capital_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, excludeChars=",")

parseImpl(instring, loc, doActions=True)

class gavo.imp.pyparsing.WordEnd(wordChars='0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~')

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 wordChars (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.

parseImpl(instring, loc, doActions=True)

class gavo.imp.pyparsing.WordStart(wordChars='0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~')

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 wordChars (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.

parseImpl(instring, loc, doActions=True)

class gavo.imp.pyparsing.ZeroOrMore(expr, stopOn=None)

Bases: _MultipleMatch

Optional repetition of zero or more of the given expression.

Parameters:

• expr - expression that must match zero or more times

• stopOn - (default= None) - expression for a terminating sentinel

  (only required if the sentinel would ordinarily match the repetition expression)

Example: similar to OneOrMore

parseImpl(instring, loc, doActions=True)

gavo.imp.pyparsing.cStyleComment = C style comment

Comment of the form /* ... */

gavo.imp.pyparsing.col(loc, strg)

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.parseString 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.

gavo.imp.pyparsing.commaSeparatedList = commaSeparatedList

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

This expression is deprecated in favor of pyparsing_common.comma_separated_list.

gavo.imp.pyparsing.conditionAsParseAction(fn, message=None, fatal=False)

gavo.imp.pyparsing.countedArray(expr, intExpr=None)

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

Example:

countedArray(Word(alphas)).parseString('2 ab cd ef')  # -> ['ab', 'cd']

# in this parser, the leading integer value is given in binary,
# '10' indicating that 2 values are in the array
binaryConstant = Word('01').setParseAction(lambda t: int(t[0], 2))
countedArray(Word(alphas), intExpr=binaryConstant).parseString('10 ab cd ef')  # -> ['ab', 'cd']

gavo.imp.pyparsing.cppStyleComment = C++ style comment

Comment of either form cStyleComment or dblSlashComment

gavo.imp.pyparsing.dblSlashComment = // comment

Comment of the form // ... (to end of line)

gavo.imp.pyparsing.delimitedList(expr, delim=',', combine=False)

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.

Example:

delimitedList(Word(alphas)).parseString("aa,bb,cc") # -> ['aa', 'bb', 'cc']
delimitedList(Word(hexnums), delim=':', combine=True).parseString("AA:BB:CC:DD:EE") # -> ['AA:BB:CC:DD:EE']

gavo.imp.pyparsing.dictOf(key, value)

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"
attr_expr = (label + Suppress(':') + OneOrMore(data_word, stopOn=label).setParseAction(' '.join))
print(OneOrMore(attr_expr).parseString(text).dump())

attr_label = label
attr_value = Suppress(':') + OneOrMore(data_word, stopOn=label).setParseAction(' '.join)

# similar to Dict, but simpler call format
result = dictOf(attr_label, attr_value).parseString(text)
print(result.dump())
print(result['shape'])
print(result.shape)  # object attribute access works too
print(result.asDict())

prints:

[['shape', 'SQUARE'], ['posn', 'upper left'], ['color', 'light blue'], ['texture', 'burlap']]
- color: light blue
- posn: upper left
- shape: SQUARE
- texture: burlap
SQUARE
SQUARE
{'color': 'light blue', 'shape': 'SQUARE', 'posn': 'upper left', 'texture': 'burlap'}

gavo.imp.pyparsing.downcaseTokens(s, l, t)

(Deprecated) Helper parse action to convert tokens to lower case. Deprecated in favor of pyparsing_common.downcaseTokens

gavo.imp.pyparsing.htmlComment = HTML comment

Comment of the form <!-- ... -->

gavo.imp.pyparsing.indentedBlock(blockStatementExpr, indentStack, indent=True)

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 (default= True)

A valid block must contain at least one blockStatement.

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("(" + Optional(delimitedList(identifier)) + ")") + ":")
func_body = indentedBlock(stmt, indentStack)
funcDef = Group(funcDecl + func_body)

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

module_body = OneOrMore(stmt)

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']]]]]]]

gavo.imp.pyparsing.infixNotation(baseExpr, opList, lpar=Suppress:("("), rpar=Suppress:(")"))

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 infixNotation. See ParserElement.enablePackrat for a mechanism to potentially improve your parser performance.

Parameters:

• baseExpr - expression representing the most basic element for the nested

• opList - list of tuples, one for each operator precedence level in the expression grammar; each tuple is of the form (opExpr, numTerms, rightLeftAssoc, parseAction), where:

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

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

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

  • parseAction 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 setParseAction(*fn) (ParserElement.setParseAction)

• lpar - expression for matching left-parentheses (default= Suppress('('))

• rpar - expression for matching right-parentheses (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 = infixNotation(integer | varname,
    [
    ('-', 1, opAssoc.RIGHT),
    (oneOf('* /'), 2, opAssoc.LEFT),
    (oneOf('+ -'), 2, opAssoc.LEFT),
    ])

arith_expr.runTests('''
    5+3*6
    (5+3)*6
    -2--11
    ''', fullDump=False)

prints:

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

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

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

gavo.imp.pyparsing.javaStyleComment = C++ style comment

Same as cppStyleComment

gavo.imp.pyparsing.line(loc, strg)

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

gavo.imp.pyparsing.lineno(loc, strg)

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.parseString 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.

gavo.imp.pyparsing.locatedExpr(expr)

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.parseWithTabs

Example:

wd = Word(alphas)
for match in locatedExpr(wd).searchString("ljsdf123lksdjjf123lkkjj1222"):
    print(match)

prints:

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

gavo.imp.pyparsing.makeHTMLTags(tagStr)

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>'
# makeHTMLTags returns pyparsing expressions for the opening and
# closing tags as a 2-tuple
a, a_end = makeHTMLTags("A")
link_expr = a + SkipTo(a_end)("link_text") + a_end

for link in link_expr.searchString(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

gavo.imp.pyparsing.makeXMLTags(tagStr)

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 makeHTMLTags

gavo.imp.pyparsing.matchOnlyAtCol(n)

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

gavo.imp.pyparsing.matchPreviousExpr(expr)

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 = matchPreviousExpr(first)
matchExpr = 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.

gavo.imp.pyparsing.matchPreviousLiteral(expr)

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 = matchPreviousLiteral(first)
matchExpr = 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 matchPreviousExpr. Do not use with packrat parsing enabled.

gavo.imp.pyparsing.nestedExpr(opener='(', closer=')', content=None, ignoreExpr=quotedString using single or double quotes)

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

Parameters:

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

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

• content - expression for items within the nested lists (default= None)

• ignoreExpr - expression for ignoring opening and closing delimiters (default= quotedString)

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 ignoreExpr 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 quotedString or a comment expression. Specify multiple expressions using an Or or MatchFirst. The default is quotedString, but if no expressions are to be ignored, then pass None for this argument.

Example:

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

code_body = nestedExpr('{', '}', ignoreExpr=(quotedString | cStyleComment))

c_function = (decl_data_type("type")
              + ident("name")
              + LPAR + Optional(delimitedList(arg), [])("args") + RPAR
              + code_body("body"))
c_function.ignore(cStyleComment)

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.searchString(source_code):
    print("%(name)s (%(type)s) args: %(args)s" % func)

prints:

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

gavo.imp.pyparsing.nullDebugAction(*args)

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

gavo.imp.pyparsing.oneOf(strs, caseless=False, useRegex=True, asKeyword=False)

Helper to quickly define a set of alternative Literals, 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 - (default= False) - treat all literals as caseless

• useRegex - (default= True) - as an optimization, will generate a Regex object; otherwise, will generate a MatchFirst object (if caseless=True or asKeyword=True, or if creating a Regex raises an exception)

• asKeyword - (default=``False``) - enforce Keyword-style matching on the generated expressions

Example:

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

prints:

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

gavo.imp.pyparsing.operatorPrecedence(baseExpr, opList, lpar=Suppress:("("), rpar=Suppress:(")"))

(Deprecated) Former name of infixNotation, will be dropped in a future release.

gavo.imp.pyparsing.originalTextFor(expr, asString=True)

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 astring containing the original parsed text.

If the optional asString 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 originalTextFor contains expressions with defined results names, you must set asString to False if you want to preserve those results name values.

Example:

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

prints:

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

class gavo.imp.pyparsing.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

Parse actions:

• convertToInteger

• convertToFloat

• convertToDate

• convertToDatetime

• stripHTMLTags

• upcaseTokens

• downcaseTokens

Example:

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

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

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

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

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

import uuid
pyparsing_common.uuid.setParseAction(tokenMap(uuid.UUID))
pyparsing_common.uuid.runTests('''
    # uuid
    12345678-1234-5678-1234-567812345678
    ''')

prints:

# 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]

# 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]

# hex numbers
100
[256]

FF
[255]

# fractions
1/2
[0.5]

-3/4
[-0.75]

# mixed fractions
1
[1]

1/2
[0.5]

-3/4
[-0.75]

1-3/4
[1.75]

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

comma_separated_list = comma separated list

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

static convertToDate(fmt='%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.setParseAction(pyparsing_common.convertToDate())
print(date_expr.parseString("1999-12-31"))

prints:

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

static convertToDatetime(fmt='%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.setParseAction(pyparsing_common.convertToDatetime())
print(dt_expr.parseString("1999-12-31T23:59:59.999"))

prints:

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

convertToFloat(l, t)

Parse action for converting parsed numbers to Python float

convertToInteger(l, t)

Parse action for converting parsed integers to Python int

static downcaseTokens(s, l, t)

Parse action to convert tokens to lower case.

fnumber = fnumber

any int or real number, returned as float

fraction = fraction

fractional expression of an integer divided by an integer, returns a float

hex_integer = hex integer

expression that parses a hexadecimal integer, returns an int

identifier = identifier

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

integer = integer

expression that parses an unsigned integer, returns 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_datetime = ISO8601 datetime

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

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, returns float

number = {real number with scientific notation | real number | signed integer}

any numeric expression, returns the corresponding Python type

real = real number

expression that parses a floating point number and returns a float

sci_real = real number with scientific notation

expression that parses a floating point number with optional scientific notation and returns a float

signed_integer = signed integer

expression that parses an integer with optional leading sign, returns an int

static stripHTMLTags(s, l, tokens)

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 = makeHTMLTags("TD")
table_text = td + SkipTo(td_end).setParseAction(pyparsing_common.stripHTMLTags)("body") + td_end
print(table_text.parseString(text).body)

Prints:

More info at the pyparsing wiki page

static upcaseTokens(s, l, t)

Parse action to convert tokens to upper case.

uuid = UUID

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

class gavo.imp.pyparsing.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

class CJK

Bases: Chinese, Japanese, Korean

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 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

class Korean

Bases: unicode_set

Unicode set for Korean Unicode Character Range

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 Korean

gavo.imp.pyparsing.pythonStyleComment = Python style comment

Comment of the form # ... (to end of line)

gavo.imp.pyparsing.removeQuotes(s, l, t)

Helper parse action for removing quotation marks from parsed quoted strings.

Example:

# by default, quotation marks are included in parsed results
quotedString.parseString("'Now is the Winter of our Discontent'") # -> ["'Now is the Winter of our Discontent'"]

# use removeQuotes to strip quotation marks from parsed results
quotedString.setParseAction(removeQuotes)
quotedString.parseString("'Now is the Winter of our Discontent'") # -> ["Now is the Winter of our Discontent"]

gavo.imp.pyparsing.replaceHTMLEntity(t)

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

gavo.imp.pyparsing.replaceWith(replStr)

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

Example:

num = Word(nums).setParseAction(lambda toks: int(toks[0]))
na = oneOf("N/A NA").setParseAction(replaceWith(math.nan))
term = na | num

OneOrMore(term).parseString("324 234 N/A 234") # -> [324, 234, nan, 234]

gavo.imp.pyparsing.srange(s)

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.)

gavo.imp.pyparsing.tokenMap(func, *args)

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).setParseAction(tokenMap(int, 16)), which will convert the parsed data to an integer using base 16.

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

hex_ints = OneOrMore(Word(hexnums)).setParseAction(tokenMap(int, 16))
hex_ints.runTests('''
    00 11 22 aa FF 0a 0d 1a
    ''')

upperword = Word(alphas).setParseAction(tokenMap(str.upper))
OneOrMore(upperword).runTests('''
    my kingdom for a horse
    ''')

wd = Word(alphas).setParseAction(tokenMap(str.title))
OneOrMore(wd).setParseAction(' '.join).runTests('''
    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']

gavo.imp.pyparsing.traceParseAction(f)

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)

@traceParseAction
def remove_duplicate_chars(tokens):
    return ''.join(sorted(set(''.join(tokens))))

wds = OneOrMore(wd).setParseAction(remove_duplicate_chars)
print(wds.parseString("slkdjs sld sldd sdlf sdljf"))

prints:

>>entering remove_duplicate_chars(line: 'slkdjs sld sldd sdlf sdljf', 0, (['slkdjs', 'sld', 'sldd', 'sdlf', 'sdljf'], {}))
<<leaving remove_duplicate_chars (ret: 'dfjkls')
['dfjkls']

gavo.imp.pyparsing.ungroup(expr)

Helper to undo pyparsing’s default grouping of And expressions, even if all but one are non-empty.

class gavo.imp.pyparsing.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, such as:

_ranges = [(0x0020, 0x007e), (0x00a0, 0x00ff),]

A unicode set can also be defined using multiple inheritance of other unicode sets:

class CJK(Chinese, Japanese, Korean):
    pass

alphanums = ''

alphas = ''

nums = ''

printables = ''

gavo.imp.pyparsing.upcaseTokens(s, l, t)

(Deprecated) Helper parse action to convert tokens to upper case. Deprecated in favor of pyparsing_common.upcaseTokens

gavo.imp.pyparsing.withAttribute(*args, **attrDict)

Helper to create a validating parse action to be used with start tags created with makeXMLTags or makeHTMLTags. Use withAttribute to qualify a starting tag with a required attribute value, to avoid false matches on common tags such as <TD> or <DIV>.

Call withAttribute 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 withClass.

To verify that the attribute exists, but without specifying a value, pass withAttribute.ANY_VALUE as the value.

Example:

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 = makeHTMLTags("div")

# only match div tag having a type attribute with value "grid"
div_grid = div().setParseAction(withAttribute(type="grid"))
grid_expr = div_grid + SkipTo(div | div_end)("body")
for grid_header in grid_expr.searchString(html):
    print(grid_header.body)

# construct a match with any div tag having a type attribute, regardless of the value
div_any_type = div().setParseAction(withAttribute(type=withAttribute.ANY_VALUE))
div_expr = div_any_type + SkipTo(div | div_end)("body")
for div_header in div_expr.searchString(html):
    print(div_header.body)

prints:

1 4 0 1 0

1 4 0 1 0
1,3 2,3 1,1

gavo.imp.pyparsing.withClass(classname, namespace='')

Simplified version of withAttribute when matching on a div class - made difficult because class is a reserved word in Python.

Example:

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 = makeHTMLTags("div")
div_grid = div().setParseAction(withClass("grid"))

grid_expr = div_grid + SkipTo(div | div_end)("body")
for grid_header in grid_expr.searchString(html):
    print(grid_header.body)

div_any_type = div().setParseAction(withClass(withAttribute.ANY_VALUE))
div_expr = div_any_type + SkipTo(div | div_end)("body")
for div_header in div_expr.searchString(html):
    print(div_header.body)

prints:

1 4 0 1 0

1 4 0 1 0
1,3 2,3 1,1