Module spelling 

Vietnamese CVC (Consonant-Vowel-Consonant) spelling validation.

Functions

apply_mark

Applies mark m to character c. Marks: 1=hat, 2=breve, 3=horn, 4=dash.

apply_tone

Applies tone t to the toneless base character c.

is_valid_cvc

Public CVC validation entry point.

is_vowel

lower

tone_of

Returns the tone number (0=none, 1=grave, 2=acute, 3=hook, 4=tilde, 5=dot)

toneless_base

Returns the toneless base vowel for a character. e.g. ‘ấ’ → ‘â’, ‘ạ’ → ‘a’, ‘ê’ → ‘ê’