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#
# scanExamples.py
#
# Illustration of using pyparsing's scan_string,transform_string, and search_string methods
#
# Copyright (c) 2004, 2006 Paul McGuire
#
from pyparsing import (
Word,
alphas,
alphanums,
Literal,
rest_of_line,
OneOrMore,
empty,
Suppress,
replace_with,
)
# 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.set_results_name("name")
+ "="
+ rest_of_line.set_results_name("value")
)
for t, s, e in macroDef.scan_string(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 rest_of_line advances past leading whitespace, does implicit lstrip during parsing
macroDef = Suppress("#define") + ident + Suppress("=") + empty + rest_of_line
macros = dict(list(macroDef.search_string(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.set_parse_action(lambda t: "_".join(t))
print("(replace namespace-scoped names with C-compatible names)")
print(scopedIdent.transform_string(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.set_parse_action(substituteMacro)
ident.ignore(macroDef)
print("(simulate #define pre-processor)")
print(ident.transform_string(testData))
#################
print("Example of a stripper")
print("----------------------")
from pyparsing import dbl_quoted_string, LineStart
# remove all string macro definitions (after extracting to a string resource table?)
stringMacroDef = Literal("#define") + ident + "=" + dbl_quoted_string + LineStart()
stringMacroDef.set_parse_action(replace_with(""))
print(stringMacroDef.transform_string(testData))
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