class Regularity

# File lib/regularity.rb, line 20
def initialize
  @str = ''
  @ended = false
end

# File lib/regularity.rb, line 82
def =~(other)
  regex =~ other
end

# File lib/regularity.rb, line 30
def append(*args)
  write interpret(*args)
end

# File lib/regularity.rb, line 61
def at_least(times, pattern)
  between [times, nil], pattern
end

# File lib/regularity.rb, line 65
def at_most(times, pattern)
  between [nil, times], pattern
end

# File lib/regularity.rb, line 53
def between(range, pattern)
  unless range.length == 2 && range.any? { |i| i.is_a?(Integer) }
    raise Regularity:Error.new('must provide an array of 2 elements, one of them must be an integer')
  end

  write '%s{%s,%s}' % [interpret(pattern), range[0], range[1]]
end

# File lib/regularity.rb, line 35
def end_with(*args)
  write '%s$', args
  @ended = true
  self
end

# File lib/regularity.rb, line 98
def inspect
  to_s
end

# File lib/regularity.rb, line 41
def maybe(*args)
  write '%s?', args
end

# File lib/regularity.rb, line 86
def method_missing(meth, *args, &block)
  regex.send(meth, *args, &block)
end

# File lib/regularity.rb, line 45
def not(*args)
  write '(?!%s)', args
end

# File lib/regularity.rb, line 49
def one_of(ary)
  write '[%s]' % ary.map { |c| escape(c) }.join('|')
end

# File lib/regularity.rb, line 73
def one_or_more(pattern)
  write '%s+', pattern
end

# File lib/regularity.rb, line 77
def regex
  Regexp.new(@str)
end

# File lib/regularity.rb, line 90
def respond_to?(meth)
  regex.respond_to?(meth) || super
end

# File lib/regularity.rb, line 25
def start_with(*args)
  raise Regularity::Error.new('#start_with? called multiple times') unless @str.empty?
  write '^%s', args
end

# File lib/regularity.rb, line 94
def to_s
  "#<Regularity:#{object_id} regex=/#{@str}/>"
end

# File lib/regularity.rb, line 69
def zero_or_more(pattern)
  write '%s*', pattern
end

# File lib/regularity.rb, line 143
def escape(pattern)
  pattern.to_s.gsub(/.+/) do |char|
    ESCAPED_CHARS.include?(char) ? "\\#{char}" : char
  end
end

# File lib/regularity.rb, line 111
def interpret(*args)
  case args.length
  when 2 then numbered_constraint(*args)
  when 1 then patterned_constraint(*args)
  else raise ArgumentError
  end
end

# File lib/regularity.rb, line 120
def numbered_constraint(count, type)
  pattern = patterned_constraint(type)
  raise Regularity::Error.new('Unrecognized pattern') if pattern.nil? || pattern.empty?
  '%s{%s}' % [pattern, count]
end

# File lib/regularity.rb, line 127
def patterned_constraint(pattern)
  escape translate(pattern)
end

# File lib/regularity.rb, line 132
def singularize(word)
  str = word.to_s
  str.end_with?('s') ? str[0..-2] : str
end

# File lib/regularity.rb, line 151
def translate(pattern)
  PATTERNS[singularize(pattern)] || pattern
end

# File lib/regularity.rb, line 104
def write(str, args=nil)
  raise Regularity::Error.new('#end_with has already been called') if @ended
  @str << (args.nil? ? str : str % interpret(*args))
  self
end