"""
Pig Latin Lexer

if a string starts with a consonant, put the consonant at the end of the word
and add the string "ay" to the end.

>Consonant   #before
>Onsonantcay #after

if a string starts with a vowel, just add "ay" to the end of the string.

>apple    #before
>appleay  #before

written using SlyLex Yacc

nick creel sp19 compiler design/programming languages
"""

from sly import Lexer

class PigLexer(Lexer):
	#token names
	tokens = { CONSONANT, VOWEL } 

	ignore = ' \t'
	#Regular expressions defining tokens
	
	CONSONANT = r'[b-zB-Z&&^eiouEIOU][A-Za-z]*'
	VOWEL = r'[aeiouAEIOU][a-zA-Z]*'

	def CONSONANT(self, t):
		```
		Test the first character in t.value.
		 If t.value[0] is a consonant, set 
		t.value equal to
		 t.value[1:] + t.value[0] + 'ay'
		then return the token.

		>>> CONSONANT("Big") == "igBay"
		```
		t.value = t.value[1:] + t.value[0] + 'ay'
		return t
	def VOWEL(self, t):	
		```
		test the first character in t.value.
		 if t.value[0] is a 
		vowel, then make t.value 
		equal to t.value + 'ay', then return
		t. 

		>>> VOWEL("apple") == "appleay"
		```
		t.value = t.value + 'ay' 
		return t

if __name__ == '__main__':
	string = "Big bad apple"
	lexer = PigLexer()
	result = ""
	for tok in lexer.tokenize(string):
		result = result + tok.value + " "
	print("Input: " + string)
	print("Result: " + result)