#! /usr/bin/perl -w
# Extract all examples from the manual source.

# This file is part of GNU Bison

# Copyright (C) 1992, 2000-2001, 2005-2006, 2009-2015, 2018-2021 Free
# Software Foundation, Inc.
#
# This program 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 of the License, or
# (at your option) any later version.
#
# This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.

# Usage: extexi [OPTION...] input-file.texi ... -- [FILES to extract]

# Look for @example environments preceded with lines such as:
#
#      @comment file c/mfcalc/calc.y
# or
#      @comment file c/mfcalc/calc.y: 3
#
# and output their content in that file (c/mfcalc/calc.y).  When
# numbers are provided, use them to decide the output order (block 1
# is output before block 2, even if the latter appears before).  The
# same number may be used several time, in which case the order of
# appearance is used.
#
# Use @ignore for code to extract that must not be part of the
# documentation.  For instance:
#
#      @ignore
#      @comment file: c++/calc++/scanner.ll
#      @example
#      // Work around an incompatibility in Flex.
#      # undef yywrap
#      # define yywrap() 1
#      @end example
#      @end ignore

use strict;

use File::Basename qw(dirname);
use File::Path qw(make_path);

# Whether we generate synclines.
my $synclines = 0;

# normalize($block)
# -----------------
# Remove Texinfo mark up.
sub normalize($)
{
  local ($_) = @_;

  # If we just remove this lines, then the compiler's tracking of
  # #lines is broken.  Leave lines that that accepted by all our tools
  # (including flex, hence the leading space), and that will be easy
  # to remove (see the Make examples-unline recipe).
  s{^\@(c |comment|dots|end (ignore|group)|ignore|group).*}{ /**/}mg;
  s/\@value\{VERSION\}/$ENV{VERSION}/g;
  s/^\@(error|result)\{\}//mg;
  s/\@([{}@])/$1/g;
  s/\@comment.*//;
  $_;
}

# Print messages only once.
my %msg;
sub message($)
{
  my ($msg) = @_;
  if (! $msg{$msg})
    {
      print STDERR "extexi: $msg\n";
      $msg{$msg} = 1;
    }
}

# The list of files we should extract.
my @file_wanted;

# Whether we should extract that file, and then under which path.  We
# check if the prefix matches.  So for instance if "foo/bar.y" is
# wanted (i.e., in @FILE_WANTED), "file: bar.y" matches.
sub file_wanted ($)
{
  my ($f) = @_;
  for my $file (@file_wanted)
    {
      # No endswith in Perl 5...
      return $file if $f eq substr($file, -length($f));
    }
  undef
}

# process ($in)
# -------------
# Read input file $in, and generate the outputs.
sub process ($)
{
  my ($in) = @_;
  use IO::File;
  my $f = new IO::File($in)
    or die "$in: cannot open: $?";
  # FILE-NAME => { BLOCK-NUM => CODE }
  my %file;

  # The latest "@comment file: FILE [BLOCK-NUM]" arguments.
  my $file;
  my $block;
  # The @example block currently read.
  my $input;
  local $_;
  while (<$f>)
    {
      if (/^\@comment file: ([^:\n]+)(?::\s*(\d+))?$/)
        {
          my $f = $1;
          $block = $2 || 1;
          if (file_wanted($f))
            {
              $file = file_wanted($f);
              message(" GEN $file");
            }
          else
            {
              message("SKIP $f");
            }
        }
      elsif ($file && /^\@(small)?example$/ .. /^\@end (small)?example$/)
        {
          if (/^\@(small)?example$/)
            {
              # Bison supports synclines, but not Flex.
              $input .= sprintf ("#line %s \"$in\"\n", $. + 1)
                if $synclines && $file =~ /\.[chy]*$/;
            }
          elsif (/^\@end (small)?example$/)
            {
              die "no contents: $file"
                if $input eq "";

              $file{$file}{$block} .= "\n" if defined $file{$file}{$block};
              $file{$file}{$block} .= normalize($input);
              $file = $input = undef;
              ++$block;
            }
          else
            {
              $input .= $_;
            }
        }
    }

  # Output the files.
  for my $file (keys %file)
    {
      make_path (dirname ($file));
      my $o = new IO::File(">$file")
        or die "$file: cannot create: $?";
      print $o $file{$file}{$_}
        for sort keys %{$file{$file}};
    }
}

my @input;
my $seen_dash = 0;
for my $arg (@ARGV)
{
  if ($seen_dash)
    {
      push @file_wanted, $arg;
    }
  elsif ($arg eq '--')
    {
      $seen_dash = 1;
    }
  elsif ($arg eq '--synclines')
    {
      $synclines = 1;
    }
  else
    {
      push @input, $arg;
    }
}
process $_
  foreach @input;


### Setup "GNU" style for perl-mode and cperl-mode.
## Local Variables:
## perl-indent-level: 2
## perl-continued-statement-offset: 2
## perl-continued-brace-offset: 0
## perl-brace-offset: 0
## perl-brace-imaginary-offset: 0
## perl-label-offset: -2
## cperl-indent-level: 2
## cperl-brace-offset: 0
## cperl-continued-brace-offset: 0
## cperl-label-offset: -2
## cperl-extra-newline-before-brace: t
## cperl-merge-trailing-else: nil
## cperl-continued-statement-offset: 2
## End: