[REBOL] Re: [REBOL parse] Parsing AEIOU and sometimes Y
From: anton:wilddsl:au at: 2-May-2007 16:33
Hi Ed,
Here's my go at it:
; y can't be a consonant, if it's preceded by a consonant
vow: charset "aeiouAEIOU"
y: charset "yY"
con: exclude charset [#"a" - #"z" #"A" - #"Z"] union vow y
y-as-vowel: [y (print "y = vowel")]
y-as-consonant: [y pos: vow :pos (print "y = consonant")] ; to be
interpreted as a consonant, y must also be followed by a vowel
vowel: [[vow | y-as-vowel] (consonant/1: [con | y-as-consonant])] ;
enable y as a consonant
consonant: [[con | y-as-consonant] (consonant/1: [con])] ; disable y as a
consonant
rule: [(consonant/1: [con | y-as-consonant]) any [consonant | vowel]]
parse "toy" rule ; y = vowel
parse "crazy" rule ; y = vowel
parse "crybaby" rule ; y = vowel; y = vowel
parse "yay" rule ; y = consonant ; y = vowel
parse "yoyo" rule ; y = consonant ; y = consonant
The whole Y issue is complicated, isn't it ?
Y can be a vowel, consonant or semi-vowel (a type of consonant)...
Regards,
Anton.
