#!/usr/bin/env python

"""A preprocessor for Python scripts implementing the *detect*
statement. Uses blockparser.py.

TODO: Use class exceptions instead of string exceptions."""

import blockparser
from types import ListType, StringType
from string import strip
from re import sub

def process(block, inDetect=0, extraIndent=0):

    def eventReplacement(matchObject):
        return "raise "+matchObject.group(1)
    
    lineNum = 0
    while lineNum < len(block):
        element = block[lineNum]
        if type(element) == StringType:
            indent = blockparser.getIndent(element)
            if strip(element)[:6] == 'detect':
                events = strip(strip(element)[6:-1])
                del block[lineNum]
                block[lineNum:lineNum] = [' '*(indent+extraIndent)
                                          +'try:',
                                          ' '*(indent+extraIndent)
                                          +'    while 1:']
                lineNum = lineNum+2
                process(block[lineNum], 1, extraIndent+4)
                lineNum = lineNum+1
                block[lineNum:lineNum] = [' '*(indent+extraIndent)+
                                          "except ("+events+"): pass"]
            else:
                if extraIndent != 0:
                    block[lineNum] = ' '*extraIndent+block[lineNum]
                block[lineNum] = sub(r"(?=\s*)('[^']*')",
                                     eventReplacement,
                                     block[lineNum])
        else:
            process(element, inDetect, extraIndent)
        lineNum = lineNum+1
    return block
    

def output(structure):
    result = ""
    for element in structure:
        if type(element) == ListType:
            result = result + output(element)
        else:
            result = result + element + "\n"
    return result


if __name__=="__main__":
    import sys
    structure = blockparser.parse(sys.argv[1])
    structure = process(structure)
    print output(structure)