# diffhelpers.py - pure Python implementation of diffhelpers.c

#

# Copyright 2009 Matt Mackall <mpm@selenic.com> and others

#

# This software may be used and distributed according to the terms of the

# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

def addlines(fp, hunk, lena, lenb, a, b):

    while True:

        todoa = lena - len(a)

        todob = lenb - len(b)

        num = max(todoa, todob)

        if num == 0:

            break

        for i in xrange(num):

            s = fp.readline()

            if s == "\\ No newline at end of file\n":

                fix_newline(hunk, a, b)

                continue

            if s == "\n":

                # Some patches may be missing the control char

                # on empty lines. Supply a leading space.

                s = " \n"

            hunk.append(s)

            if s.startswith('+'):

                b.append(s[1:])

            elif s.startswith('-'):

                a.append(s)

            else:

                b.append(s[1:])

                a.append(s)

    return 0

def fix_newline(hunk, a, b):

    l = hunk[-1]

    # tolerate CRLF in last line

    if l.endswith('\r\n'):

        hline = l[:-2]

    else:

        hline = l[:-1]

    if hline.startswith((' ', '+')):

        b[-1] = hline[1:]

    if hline.startswith((' ', '-')):

        a[-1] = hline

    hunk[-1] = hline

    return 0

def testhunk(a, b, bstart):

    alen = len(a)

    blen = len(b)

    if alen > blen - bstart:

        return -1

    for i in xrange(alen):

        if a[i][1:] != b[i + bstart]:

            return -1

    return 0