#
# scanExamples.py
#
# Illustration of using pyparsing's scanString,transformString, and searchString methods
#
# Copyright (c) 2004, 2006 Paul McGuire
#
from pyparsing import Word,alphas,alphanums,Literal,restOfLine,OneOrMore,\
empty, Suppress, replaceWith
# simulate some C++ code
testData = """
#define MAX_LOCS=100
#define USERNAME = "floyd"
#define PASSWORD = "swordfish"
a = MAX_LOCS;
CORBA::initORB("xyzzy", USERNAME, PASSWORD );
"""
#################
print "Example of an extractor"
print "----------------------"
# simple grammar to match #define's
ident = Word(alphas, alphanums+"_")
macroDef = Literal("#define") + ident.setResultsName("name") + "=" + restOfLine.setResultsName("value")
for t,s,e in macroDef.scanString( testData ):
print t.name,":", t.value
# or a quick way to make a dictionary of the names and values
# (return only key and value tokens, and construct dict from key-value pairs)
# - empty ahead of restOfLine advances past leading whitespace, does implicit lstrip during parsing
macroDef = Suppress("#define") + ident + Suppress("=") + empty + restOfLine
macros = dict(list(macroDef.searchString(testData)))
print "macros =", macros
print
#################
print "Examples of a transformer"
print "----------------------"
# convert C++ namespaces to mangled C-compatible names
scopedIdent = ident + OneOrMore( Literal("::").suppress() + ident )
scopedIdent.setParseAction(lambda t: "_".join(t))
print "(replace namespace-scoped names with C-compatible names)"
print scopedIdent.transformString( testData )
# or a crude pre-processor (use parse actions to replace matching text)
def substituteMacro(s,l,t):
if t[0] in macros:
return macros[t[0]]
ident.setParseAction( substituteMacro )
ident.ignore(macroDef)
print "(simulate #define pre-processor)"
print ident.transformString( testData )
#################
print "Example of a stripper"
print "----------------------"
from pyparsing import dblQuotedString,LineStart
# remove all string macro definitions (after extracting to a string resource table?)
stringMacroDef = Literal("#define") + ident + "=" + dblQuotedString + LineStart()
stringMacroDef.setParseAction( replaceWith("") )
print stringMacroDef.transformString( testData )
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