#--------------------------------------------------------------------
# Copyright (c) 1999-2004, International Business Machines
# Corporation and others. All Rights Reserved.
#--------------------------------------------------------------------

# According to the pinyin definitions I've been able to find:
# 'a', 'e' are the preferred bases
# otherwise 'o'
# otherwise last vowel

# The trailing form of syllables are the following:
#         "a", "ai", "ao", "an", "ang",
#         "o", "ou", "ong",
#         "e", "ei", "er", "en", "eng",
#         "i", "ia", "iao", "ie", "iu", "ian", "in", "iang", "ing", "iong",
#         "u", "ua", "uo", "uai", "ui", "uan", "un", "uang", "ueng",
#         "ü", "üe", "üan", "ün"
# so the letters the tone will 'hop' are:

::NFD (NFC);
$tone = [\u0304\u0301\u030C\u0300\u0306] ;

# Move the tone to the end of a syllable, and convert to number
e {($tone) r} > r &tone-digit($1);
($tone) ( [i o n u {o n} {n g}]) > $2 &tone-digit($1);
($tone) > &tone-digit($1);

# The following backs up until it finds the right vowel, then deposits the tone

$vowel = [aAeEiIoOuUüÜ];
$consonant = [[a-z A-Z] - [$vowel]];
$digit = [1-5];
$1 &digit-tone($3) $2 < ([aAeE]) ($vowel* $consonant*) ($digit);
$1 &digit-tone($3) $2 < ([oO]) ([$vowel-[aeAE]]* $consonant*) ($digit);
$1 &digit-tone($3) $2 < ($vowel) ($consonant*) ($digit);
&digit-tone($1) < [:letter:] {($digit)};

::NFC (NFD);