# 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);
$tone = [̄́̌̀̆] ;
# Move the tone to the end of a syllable, and convert to number
e {($tone) r} → r &Pinyin-NumericPinyin($1);
($tone) ( [i o n u {o n} {n g}]) → $2 &Pinyin-NumericPinyin($1);
($tone) → &Pinyin-NumericPinyin($1);
# The following backs up until it finds the right vowel, then deposits the tone
$vowel = [aAeEiIoOuU {ü} {Ü} vV];
$consonant = [[a-z A-Z] - [$vowel]];
$digit = [1-5];
$1 &NumericPinyin-Pinyin($3) $2 ← ([aAeE]) ($vowel* $consonant*) ($digit);
$1 &NumericPinyin-Pinyin($3) $2 ← ([oO]) ([$vowel-[aeAE]]* $consonant*) ($digit);
$1 &NumericPinyin-Pinyin($3) $2 ← ($vowel) ($consonant*) ($digit);
&NumericPinyin-Pinyin($1) ← [:letter:] {($digit)};
::NFC (NFD);