# # 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 )