#! /usr/bin/env perl
#
# hyphenex.pl
#
# This small filter converts a hyphenation exception log article for
# TUGBoat to a real \hyphenation block.
#
# Written by Werner Lemberg <wl@gnu.org>.
#
# Version 1.3 (2008/05/20)
#
# Public domain.
#
#
# Usage:
#   perl hyphenex.pl < tugboat-article > hyphenation-exceptions

# print header
print "% Hyphenation exceptions for US English,\n";
print "% based on hyphenation exception log articles in TUGboat.\n";
print "%\n";
print "% Copyright 2021 TeX Users Group.\n";
print "% You may freely use, modify and/or distribute this file.\n";
print "%\n";
print "% This is an automatically generated file.  Do not edit!\n";
print "%\n";
print "% Please contact the TUGboat editorial staff <tugboat\@tug.org>\n";
print "% for corrections and omissions.\n";
print "\n";
print "\\hyphenation{\n";

while (<>) {
  # retain only lines starting with \1 ... \6 or \tabalign
  next if not (m/^\\[123456]/ || m/^\\tabalign/);
  # remove final newline
  chop;
  # remove all TeX commands except \1 ... \6
  s/\\[^123456\s{]+//g;
  # remove all paired { ... }
  1 while s/{(.*?)}/\1/g;
  # skip lines which now have only whitespace before `&'
  next if m/^\s*&/;
  # remove comments
  s/%.*//;
  # remove trailing whitespace
  s/\s*$//;
  # remove trailing `*' (used as a marker in the document)
  s/\*$//;
  # split at whitespace
  @field = split(' ');
  if ($field[0] eq "\\1" || $field[0] eq "\\4") {
    print "  $field[2]\n";
  }
  elsif ($field[0] eq "\\2" || $field[0] eq "\\5") {
    print "  $field[2]\n";
    # handle multiple suffixes separated by commata
    @suffix_list = split(/,/, "$field[3]");
    foreach $suffix (@suffix_list) {
      print "  $field[2]$suffix\n";
    }
  }
  elsif ($field[0] eq "\\3" || $field[0] eq "\\6") {
    # handle multiple suffixes separated by commata
    @suffix_list = split(/,/, "$field[3],$field[4]");
    foreach $suffix (@suffix_list) {
      print "  $field[2]$suffix\n";
    }
  }
  else {
    # for `&', split at `&' with trailing whitespace
    @field = split(/&\s*/);
    print "  $field[1]\n";
  }
}

# print trailer
print "}\n";
print "\n";
print "% EOF\n";
