#!/usr/bin/env python
# 
# Copyright (C) 2007 Terry < snip, not in public ^_^ >
#
# This software is provided 'as-is', without any express or implied
# warranty.  In no event will the authors be held liable for any damages
# arising from the use of this software.
#
# Permission is granted to anyone to use this software for any purpose,
# including commercial applications, and to alter it and redistribute it
# freely, subject to the following restrictions:
#
# 1. The origin of this software must not be misrepresented; you must not
#    claim that you wrote the original software. If you use this software
#    in a product, an acknowledgment in the product documentation would be
#    appreciated but is not required.
# 2. Altered source versions must be plainly marked as such, and must not be
#    misrepresented as being the original software.
# 3. This notice may not be removed or altered from any source distribution.
#
# < snip again >
#
#############################################################################

""" -- pdpp.py --

 A simple Python-written Document Pre-Processor.

 Purpose:
     Allow a simple syntax for defining constants, macros, variables, and
     other associated items. 

     And combine this with a simple style of text and formating instructions 
     To create a easy way of generating an HTML document.
"""

import sys, os
import re
import optparse

EXIT_SUCCESS    =   0
EXIT_FAILURE    =   1

class ConstantNotDefinedError(Exception):
    pass

class PreProcessor:
    """Simple text preprocessor
    
    #define FOO bar  -> causes PrePrcessor#defines[] to have a dictionary
    appended as { 'FOO' : bar }. The add_define() and get_define() methods 
    insert a key,value and fetch a value by key.

    #macro ....
    """
    defines = []
    macros = []
    
    def __init__(self):
        pass
    
    def add_define(self, const, value):
        "Register a constant as translating to value with the preprocessor"
        p = { "%s" % const : value }
        self.defines.append(p)

    def get_define(self, const):
        """Access a stored constant and return it's definition (value)

        ThrowsConstantNotDefinedError if constant is not defined"""
        for hash in self.defines:
            for key in hash:
                if key == "%s" % const:
                    return hash[key]
                #raise ConstantNotDefinedError, "%s not defined!" % key

    def add_macro(self):
        pass

    def get_macro(self, macro):
        pass

    def parse(self, file):
        lines = file.readlines()
        for ln in lines:
            if re.match(r'^#.*', ln):
                cmd=ln.split(' ')
                if cmd[0].lower() == '#define':
                    val=' '.join(cmd[2:])
                    self.add_define( cmd[1], val)
        return True


def usage():
    sys.stderr.write("write me")
    sys.exit(EXIT_FAILURE)

def main(argv):
    try:
        fp = file('./test.txt')
        pp=PreProcessor()
        pp.parse(fp)
        print pp.defines,"\n\n\n"
        print pp.get_define('OS')
        print pp.get_define('VERSION')
        print pp.get_define('VIM')
        print pp.get_define('undefined')

    except IOError:
        usage()




if __name__ == "__main__":
    main(sys.argv)