"""Module to analyze Python source code; for syntax coloring tools.

Interface:
    tags = fontify(pytext, searchfrom, searchto)

The 'pytext' argument is a string containing Python source code.
The (optional) arguments 'searchfrom' and 'searchto' may contain a slice in pytext. 
The returned value is a list of tuples, formatted like this:
    [('keyword', 0, 6, None), ('keyword', 11, 17, None), ('comment', 23, 53, None), etc. ]
The tuple contents are always like this:
    (tag, startindex, endindex, sublist)
tag is one of ('comment', 'string', 'keyword', 'function', 'class')
sublist is not used, hence always None. 
"""

# Based on FontText.py by Mitchell S. Chapman,
# which was modified by Zachary Roadhouse,
# then un-Tk'd by Just van Rossum.
# Many thanks for regular expression debugging & authoring are due to:
#    Tim (the-incredib-ly y'rs) Peters and Cristian Tismer
# So, who owns the copyright? ;-) How about this:
# Copyright 1996-1997: 
#    Mitchell S. Chapman,
#    Zachary Roadhouse,
#    Tim Peters,
#    Just van Rossum
#
# Version 0.4 - changes copyright (C) 2001 Mark Pilgrim (f8dy@diveintopython.org)
#   2001/02/05 - MAP - distinguish between class and function identifiers
#   2001/03/21 - MAP - get keywords from keyword module (instead of hard-coded list)
#   2001/03/22 - MAP - use re module instead of deprecated regex module

__version__ = "0.4"

import string, re, keyword

# Build up a regular expression which will match anything
# interesting, including multi-line triple-quoted strings.
commentPat = "#.*"

pat = "q[^\q\n]*(\\\\[\000-\377][^\q\n]*)*q"
quotePat = string.replace(pat, "q", "'") + "|" + string.replace(pat, 'q', '"')

# Way to go, Tim!
pat = """
    qqq
    [^\\q]*
    (
        (    \\\\[\000-\377]
        |    q
            (    \\\\[\000-\377]
            |    [^\\q]
            |    q
                (    \\\\[\000-\377]
                |    [^\\q]
                )
            )
        )
        [^\\q]*
    )*
    qqq
"""
pat = string.join(string.split(pat), '')    # get rid of whitespace
tripleQuotePat = string.replace(pat, "q", "'") + "|" + string.replace(pat, 'q', '"')

# Build up a regular expression which matches all and only
# Python keywords. This will let us skip the uninteresting
# identifier references.
# nonKeyPat identifies characters which may legally precede
# a keyword pattern.
nonKeyPat = "(^|[^a-zA-Z0-9_.\"'])"
keywordsPat = string.join(keyword.kwlist, "|")
keyPat = nonKeyPat + "(" + keywordsPat + ")" + nonKeyPat

matchPat = keyPat + "|" + commentPat + "|" + tripleQuotePat + "|" + quotePat
matchRE = re.compile(matchPat)

idKeyPat = "[ \t]*[A-Za-z_][A-Za-z_0-9.]*"    # Ident w. leading whitespace.
idRE = re.compile(idKeyPat)

def fontify(pytext, searchfrom=0, searchto=None):
    if searchto is None:
        searchto = len(pytext)
    tags = []
    commentTag = 'comment'
    stringTag = 'string'
    keywordTag = 'keyword'
    functionTag = 'function'
    classTag = 'class'

    start = 0
    end = searchfrom
    while 1:
        matchObject = matchRE.search(pytext, end)
        if not matchObject: break
        (start, end) = matchObject.span()
        match = matchObject.group(0)
        c = match[0]
        if c not in "#'\"":
            # Must have matched a keyword.
            if start <> searchfrom:
                # there's still a redundant char before and after it, strip!
                match = match[1:-1]
                start = start + 1
            else:
                # this is the first keyword in the text.
                # Only a space at the end.
                match = match[:-1]
            end = end - 1
            tags.append((keywordTag, start, end, None))
            # If this was a defining keyword, look ahead to the
            # following identifier.
            if match in ["def", "class"]:
                idMatchObject = idRE.search(pytext, end)
                if idMatchObject:
                    (start, end) = idMatchObject.span()
                    match = idMatchObject.group(0)
                    tags.append(((match=='def') and functionTag or classTag, start, end, None))
        elif c == "#":
            tags.append((commentTag, start, end, None))
        else:
            tags.append((stringTag, start, end, None))
    return tags

def test(path):
    f = open(path)
    text = f.read()
    f.close()
    tags = fontify(text)
    for tag, start, end, sublist in tags:
        print tag, `text[start:end]`, start, end
