#!/usr/bin/perl
# Copyright (C) 2012 Free Software Foundation, Inc.
#
# This file is part of GCC.
#
# GCC is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3, or (at your option)
# any later version.
#
# GCC is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with GCC; see the file COPYING.  If not, write to
# the Free Software Foundation, 51 Franklin Street, Fifth Floor,
# Boston, MA 02110-1301, USA.

# This script parses a .diff file generated with 'diff -up' or 'diff -cp'
# and writes a skeleton ChangeLog file to stdout. It does not try to be
# very smart when parsing function names, but it produces a reasonable
# approximation.
#
# Author: Diego Novillo <dnovillo@google.com> and
#         Cary Coutant <ccoutant@google.com>

# Change these settings to reflect your profile.
$username = $ENV{'USER'};
$name = `finger $username | grep -o 'Name: .*'`;
@n = split(/: /, $name);
$name = @n[1]; chop($name);
$addr = $username . "\@my.domain.org";
$date = `date +%Y-%m-%d`; chop ($date);


#-----------------------------------------------------------------------------
# Program starts here. You should not need to edit anything below this
# line.
#-----------------------------------------------------------------------------
if ( $#ARGV != 0 ) {
    $prog = `basename $0`; chop ($prog);
    print "usage: $prog file.diff\n\n";
    print "Adds a ChangeLog template to the start of file.diff\n";
    print "It assumes that file.diff has been created with -up or -cp.\n";
    exit 1;
}

$diff = $ARGV[0];
$dir = `dirname $diff`; chop ($dir);
$basename = `basename $diff`; chop ($basename);
$cl = `mktemp /tmp/$basename.XXXXXX` || exit 1; chop ($cl);
$hdrline = "$date  $name  <$addr>";

open (CLFILE, ">$cl") or die "Could not open file $cl for writing";

print CLFILE "$hdrline\n\n";

# For every file in the .diff print all the function names in ChangeLog
# format.
$bof = 0;
open (DFILE, $diff) or die "Could not open file $diff for reading";
while (<DFILE>) {
    # Check if we found a new file.
    if (/^\+\+\+ (b\/)?(\S+)/) {
	# If we have not seen any function names in the previous file (ie,
	# $bof == 1), we just write out a ':' before starting the next
	# file.
	if ($bof == 1) {
	    print CLFILE ":\n";
	}
	$filename = $2;
	print CLFILE "\t* $filename";
	$bof = 1;
    }

    # Remember the last line in a unified diff block that might start
    # a new function.
    if (/^[-+ ]([a-zA-Z0-9_].*)/) {
        $save_fn = $1;
    }

    # If we find a new function, print it in brackets.  Special case if
    # this is the first function in a file.  
    #
    # Note that we don't try too hard to find good matches.  This should
    # return a superset of the actual set of functions in the .diff file.
    #
    # The first two patterns work with context diff files (diff -c). The
    # third pattern works with unified diff files (diff -u).
    #
    # The fourth pattern looks for the starts of functions or classes
    # within a unified diff block.

    if (/^\*\*\*\*\*\** ([a-zA-Z0-9_].*)/
        || /^[\-\+\!] ([a-zA-Z0-9_]+)[ \t]*\(.*/
	|| /^@@ .* @@ ([a-zA-Z0-9_].*)/
	|| /^[-+ ](\{)/)
      {
	$_ = $1;
	my $fn;
	if (/^\{/) {
	    # Beginning of a new function.
	    $_ = $save_fn;
	} else {
	    $save_fn = "";
	}
	if (/;$/) {
	    # No usable function name found.
	} elsif (/^((class|struct|union|enum) [a-zA-Z0-9_]+)/) {
	    # Discard stuff after the class/struct/etc. tag.
	    $fn = $1;
	} elsif (/([a-zA-Z0-9_][^(]*)\(/) {
	    # Discard template and function parameters.
	    $fn = $1;
	    1 while ($fn =~ s/<[^<>]*>//);
	    $fn =~ s/[ \t]*$//;
	}
	if ($fn && $seen_names{$fn} == 0) {
	    # If this is the first function in the file, we display it next
	    # to the filename, so we need an extra space before the opening
	    # brace.
	    if ($bof) {
		print CLFILE " ";
		$bof = 0;
	    } else {
		print CLFILE "\t";
	    }

	    print CLFILE "($fn):\n";
	    $seen_names{$fn} = 1;
	}
    }
}

# If we have not seen any function names (ie, $bof == 1), we just
# write out a ':'. This happens when there is only one file with no
# functions.
if ($bof == 1) {
    print CLFILE ":\n";
}

print CLFILE "\n";
close (DFILE);

# Concatenate the ChangeLog template and the original .diff file.
system ("cat $diff >>$cl && mv $cl $diff") == 0
    or die "Could not add the ChangeLog entry to $diff";

exit 0;