"""Base class for real-world parsers (such as parser.Parser)"""
from simpleparse.stt.TextTools.TextTools import *
from simpleparse.generator import Generator
class BaseParser:
"""Class on which real-world parsers build
Normally you use a sub-class of this class, such as
simpleparser.parser.Parser
"""
_rootProduction = ""
# primary API...
def parse( self, data, production=None, processor=None, start=0, stop=None):
"""Parse data with production "production" of this parser
data -- data to be parsed, a Python string, for now
production -- optional string specifying a non-default production to use
for parsing data
processor -- optional pointer to a Processor or MethodSource object for
use in determining reporting format and/or post-processing the results
of the parsing pass. Can be None if neither is desired (default)
start -- starting index for the parsing, default 0
stop -- stoping index for the parsing, default len(data)
"""
self.resetBeforeParse()
if processor is None:
processor = self.buildProcessor()
if stop is None:
stop = len(data)
value = tag( data, self.buildTagger( production, processor), start, stop )
if processor and callable(processor):
return processor( value, data )
else:
return value
# abstract methods
def buildProcessor( self ):
"""Build default processor object for this parser class
The default implementation returns None. The processor
can either implement the "method source" API (just provides
information about Callouts and the like), or the processor
API and the method-source API. The processor API merely
requires that the object be callable, and have the signature:
object( (success, children, nextPosition), buffer)
(Note: your object can treat the first item as a single tuple
if it likes).
See: simpleparse.processor module for details.
"""
return None
def buildTagger( self, name, processor ):
"""Build the tag-table for the parser
This method must be implemented by your base class and _not_
call the implementation here.
"""
raise NotImplementedError( """Parser sub-class %s hasn't implemented a buildTagger method"""%(self.__class__.__name__))
def resetBeforeParse( self ):
"""Called just before the parser's parse method starts working,
Allows you to set up special-purpose structures, such as stacks
or local storage values. There is no base implementation. The
base implementation does nothing.
"""
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