Parslet Woes

failing_example.rb

require 'parslet'
require 'parslet/convenience'
require 'pp'

def parse(input)
  parser = SongParser.new
  begin
    tree = parser.parse(input)
  rescue Parslet::ParseFailed => error
    puts error, parser.root.error_tree
  end
  tree
end

class SongParser < Parslet::Parser
  # Convenience: End of Line / Whitespace matchers
  rule(:line_end) { match('[\r\n]').repeat(1) }

  # Elements
  rule(:syllable) { ((timecode | line_end).absent? >> any).repeat(1) }
  rule(:timecode) {
    str('[') >> match('\d').repeat(1).as(:min) >>
    str(':') >> match('\d').repeat(1).as(:sec) >>
    str(':') >> match('\d').repeat(1).as(:msec) >> str(']')
  }

  # Groups
  rule(:pair) { timecode >> syllable.as(:syllable) }
  rule(:line) { (pair.repeat >> timecode.maybe).as(:line) >> line_end }
  rule(:song) { line.repeat.as(:lines) }

  root :song
end

input  = "[01:06:07]Beat[01:06:30]ing [01:06:56]up [01:06:83]the [01:07:09]wrong "
input << "[01:07:52]guy[01:08:03]junk\n[01:08:50]Oh [01:08:93]man![01:09:48]\n"
input_no_trailing_new_line = input.chomp

# puts "INPUT"
# puts input
# puts

def parser
  SongParser.new
end

# pp parser.line.parse_with_debug("[01:06:07]syll[01:06:07]junk[01:06:07]\n")
tree = parser.parse(input)

Syllable = Struct.new(:min, :text)
transform = Parslet::Transform.new do
  rule(:min=>simple(:min), :sec=>simple(:sec), :msec=>simple(:msec), :syllable=>simple(:text)) { Syllable.new(min, text) }
  rule(:min=>simple(:min), :sec=>simple(:sec), :msec=>simple(:msec)) { Syllable.new(min, nil) }
  rule(:line => sequence(:syllables)) { syllables.last.text = nil; syllables }
end
pp transform.apply(tree)