Module pyparsing :: Class PrecededBy

Class PrecededBy

source code

     object --+        
              |        
  ParserElement --+    
                  |    
ParseElementEnhance --+
                      |
                     PrecededBy

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:

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
Instance Methods
 
__init__(self, expr, retreat=None)
x.__init__(...) initializes x; see help(type(x)) for signature
source code
 
parseImpl(self, instring, loc=0, doActions=True) source code

Inherited from ParseElementEnhance: __str__, checkRecursion, ignore, leaveWhitespace, streamline, validate

Inherited from ParserElement: __add__, __and__, __call__, __eq__, __hash__, __invert__, __mul__, __ne__, __or__, __radd__, __rand__, __repr__, __req__, __rmul__, __rne__, __ror__, __rsub__, __rxor__, __sub__, __xor__, addCondition, addParseAction, canParseNext, copy, matches, parseFile, parseString, parseWithTabs, postParse, preParse, runTests, scanString, searchString, setBreak, setDebug, setDebugActions, setFailAction, setName, setParseAction, setResultsName, setWhitespaceChars, split, suppress, transformString, tryParse

Inherited from object: __delattr__, __format__, __getattribute__, __new__, __reduce__, __reduce_ex__, __setattr__, __sizeof__, __subclasshook__

Static Methods

Inherited from ParserElement: enablePackrat, inlineLiteralsUsing, resetCache, setDefaultWhitespaceChars

Class Variables

Inherited from ParserElement: DEFAULT_WHITE_CHARS, packrat_cache, packrat_cache_lock, packrat_cache_stats, verbose_stacktrace

Properties

Inherited from object: __class__

Method Details

__init__(self, expr, retreat=None)
(Constructor)

source code 

x.__init__(...) initializes x; see help(type(x)) for signature

Overrides: object.__init__
(inherited documentation)

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

source code 
Overrides: ParserElement.parseImpl