generate random string from a canonical for, useful for software responding like humans

text-generator.rb

#!/usr/bin/env ruby
# generate a single sentence from a canonical form
# canonical sentence is a multi sentences combined in one
# form, generator will generate a sentence from it randomly
# based on the form, for example:
# "Hello [Emad|Elsaid]" , may generate "Hello Emad" or
# "Hello Elsaid" the result is random.
# also you could nest [] inside each other to gain a multi level
# canonical sentence example:
# "[[Hi|Hello] [Emad|elsaid] | good [morning|night] sir]"
def generate(result)
	while result.include? '[' 
		s_start = result.index '['
		s_end = s_start+1
		while s_end<result.length and result[s_end]!=']'
			s_start = s_end if result[s_end] == '['
			s_end += 1
		end
		sentence = result[(s_start+1)...s_end]
		sentence = sentence.split '|'
		result = result[0...s_start] + sentence.sample + result[s_end+1...result.length]
	end
	result
end

10.times do
	puts generate '[Hello|Hi] my [friend|dear], how [are you [today|these days]|is your brother]?'
end

# Hello my friend, how is your brother?
# Hi my dear, how is your brother?
# Hello my dear, how is your brother?
# Hello my dear, how is your brother?
# Hi my friend, how is your brother?
# Hi my friend, how is your brother?
# Hello my friend, how are you these days?
# Hello my friend, how is your brother?
# Hello my friend, how are you these days?
# Hi my friend, how is your brother?

Decided to write this equivalent string. Shows usage, and may be easier to track nesting.

def choices(array)                                              
  '[' + array.join('|') + ']'                                   
end                                                             

greetings = choices(%w[Hello Hi Hey])                           
titles = choices(%w[friend dear])                               
concerns = choices(                                             
  [                                                             
    "are you #{choices(['today', 'these days'])}",              
    "is your #{choices(%w[sister mother father brother])}"      
   ]                                                             
)

20.times do                                                     
  puts generate("#{greetings} my #{titles}, how #{concerns}?") 
end