String matching, . matches any char, * means to repeat zero or at least one times.

StringPatternMatching_studyCode.rb

def isMatch(text, pattern)
  if pattern.length == 1 && text.length == 0
    return false  # "", "a"  return false
  end
  if pattern.length == 1 && text.length == 1 && pattern == '.'
    return true  # "a" "." return true
  end
  
  #"" "a*"
  
  if pattern.length == 1 
    return text == pattern # "a" "a" pattern .
  end

  test_pattern = pattern[0] #
  star = true if pattern[1] == '*'
  
  match = false  
  if star
    match ||= isMatch(text, pattern.slice(2, pattern.length))
    match ||= isMatch(text.slice(1, text.length), pattern) if text[0] == test_pattern
  elsif text[0] == test_pattern
    match ||= isMatch(text.slice(1, text.length), pattern.slice(1, pattern.length))
  end  
  return match
end