extract logic of "zipping" music and lyrics to a new class

lib/gly.rb

@@ -7,6 +7,7 @@ module Gly; end
 headers
 lyrics
 markup
+music_with_lyrics
 document
 document_gabc_convertor
 document_ly_convertor

lib/gly/gabc_convertor.rb

@@ -11,70 +11,12 @@ def convert(score, out=StringIO.new)
 
       out.puts '%%'
 
-      lyric_enum = score.lyrics.each_syllable.to_enum
-
-      score.music.each_with_index do |mus_chunk,i|
-        begin
-          next_syl = lyric_enum.peek
-          out.print lyric_enum.next if next_syl == ' '
-        rescue StopIteration
-          next_syl = ''
-        end until next_syl != ' '
-
-        if no_lyrics? mus_chunk, next_syl
-          if i == score.music.size - 1
-            out.print ' '
-          end
-        else
-          # regular music chunk
-          begin
-            out.print strip_directives lyric_enum.next
-          rescue StopIteration
-            out.print ' ' if i > 0 # don't add space at the very beginning
-          end
-        end
-
-        out.print "(#{mus_chunk})"
-        if no_lyrics?(mus_chunk, next_syl) &&
-           i != (score.music.size - 1) &&
-           ! score.lyrics.empty?
-          out.print ' '
-        end
+      score.music_with_lyrics.each_pair do |music_chunk, lyric_chunk|
+        out.print lyric_chunk if lyric_chunk
+        out.print "(#{music_chunk})" if music_chunk
       end
 
       return out
     end
-
-    def no_lyrics?(music_chunk, syllable)
-      clef?(music_chunk) ||
-        (nonlyrical_chunk?(music_chunk) &&
-         ! nonlyrical_lyrics?(syllable))
-    end
-
-    def clef?(chunk)
-      chunk =~ /\A[cf][1-4]\Z/
-    end
-
-    def without_differentiae(chunk)
-      chunk.gsub /(([,`])|(:[:']?)|(;[1-6]?))/, ''
-    end
-
-    def without_breaks(chunk)
-      chunk.gsub /[zZ]/, ''
-    end
-
-    # is the given music chunk capable of bearing lyrics?
-    def nonlyrical_chunk?(chunk)
-      chunk.size > 0 &&
-        without_breaks(without_differentiae(chunk)).empty?
-    end
-
-    def nonlyrical_lyrics?(syl)
-      syl =~ /\A\s*!/ || syl =~ /\A\s*\*\Z/
-    end
-
-    def strip_directives(syl)
-      syl.sub(/(\s*)!/, '\1') # exclamation mark at the beginning - place even under nonlyrical music chunk
-    end
   end
 end

lib/gly/music_with_lyrics.rb

@@ -0,0 +1,78 @@
+module Gly
+  # knows how to "zip" music and lyric chunks together
+  class MusicWithLyrics
+    def initialize(music, lyrics)
+      @music = music
+      @lyrics = lyrics
+    end
+
+    def each_pair
+      return enum_for(:each_pair) unless block_given?
+
+      lyric_enum = @lyrics.each_syllable.to_enum
+
+      @music.each_with_index do |mus_chunk,i|
+        begin
+          next_syl = lyric_enum.peek
+          yield nil, lyric_enum.next if next_syl == ' '
+        rescue StopIteration
+          next_syl = ''
+        end until next_syl != ' '
+
+        if no_lyrics? mus_chunk, next_syl
+          if i == @music.size - 1
+            yield nil, ' '
+          end
+        else
+          # regular music chunk
+          begin
+            lyr = strip_directives lyric_enum.next
+          rescue StopIteration
+            lyr = ' ' if i > 0 # don't add space at the very beginning
+          end
+        end
+
+        yield mus_chunk, lyr
+        if no_lyrics?(mus_chunk, next_syl) &&
+           i != (@music.size - 1) &&
+           ! @lyrics.empty?
+          yield nil, ' '
+        end
+      end
+    end
+
+    private
+
+    def no_lyrics?(music_chunk, syllable)
+      clef?(music_chunk) ||
+        (nonlyrical_chunk?(music_chunk) &&
+         ! nonlyrical_lyrics?(syllable))
+    end
+
+    def clef?(chunk)
+      chunk =~ /\A[cf][1-4]\Z/
+    end
+
+    def without_differentiae(chunk)
+      chunk.gsub /(([,`])|(:[:']?)|(;[1-6]?))/, ''
+    end
+
+    def without_breaks(chunk)
+      chunk.gsub /[zZ]/, ''
+    end
+
+    # is the given music chunk capable of bearing lyrics?
+    def nonlyrical_chunk?(chunk)
+      chunk.size > 0 &&
+        without_breaks(without_differentiae(chunk)).empty?
+    end
+
+    def nonlyrical_lyrics?(syl)
+      syl =~ /\A\s*!/ || syl =~ /\A\s*\*\Z/
+    end
+
+    def strip_directives(syl)
+      syl.sub(/(\s*)!/, '\1') # exclamation mark at the beginning - place even under nonlyrical music chunk
+    end
+  end
+end

lib/gly/score.rb

@@ -12,5 +12,9 @@ def initialize
     def empty?
       @headers.empty? && @lyrics.empty? && @music.empty?
     end
+
+    def music_with_lyrics
+      MusicWithLyrics.new(music, lyrics)
+    end
   end
 end

tests/music_with_lyrics.rb

@@ -0,0 +1,28 @@
+require_relative 'test_helper'
+
+class TestMusicWithLyrics < GlyTest
+  include Gly
+
+  def assert_translates(gly, expected)
+    doc = Parser.new.parse(StringIO.new(gly))
+    score = doc.scores[0]
+    zipped = MusicWithLyrics.new(score.music, score.lyrics)
+    assert_equal zipped.each_pair.to_a, expected
+  end
+
+  def two_monosyllabic_words
+    assert_translates("a a\n\\l i i", [['a', 'i'], [nil, ' '], ['a', 'i']])
+  end
+
+  def test_one_word_and_divisio
+    assert_translates("a a ::\nA -- men", [['a', 'A'], ['a', 'men'], [nil, ' '], ['::', nil]])
+  end
+
+  def test_divisio
+    assert_translates("a , a\n\\l x x", [['a', 'x'], [nil, ' '], [',', nil], [nil, ' '], ['a', 'x']])
+  end
+
+  def test_force_under_divisio
+    assert_translates("a , a\n\\l x !forced x", [['a', 'x'], [nil, ' '], [',', 'forced'], [nil, ' '], ['a', 'x']])
+  end
+end

tests/run.rb

@@ -2,3 +2,4 @@
 require_relative 'no_crash'
 require_relative 'string_helpers_test'
 require_relative 'parser'
+require_relative 'music_with_lyrics'