Added specifications, a pluggable RNG, include? and splice() operatio…

…ns for MusicStructure, and some semantic changes to Repeat. Also fixed a bug in Chord#transpose and handle the case where there may be nothing to transpose.

Rakefile

@@ -0,0 +1,4 @@
+require 'spec/rake/spectask'
+
+Spec::Rake::SpecTask.new
+task :default => :spec

lib/music.rb

@@ -16,7 +16,7 @@
 
 class Array
   def rand
-    self[(Kernel::rand * size).floor]
+    self[(Music::rand * size).floor]
   end
 end
 
@@ -54,6 +54,17 @@ def self.Hertz(pitch)
     end
   end
 
+  # Pluggable random number generator support. The default RNG may be
+  # replaced, e.g. for deterministic unit testing.
+  class RNG
+    def rand; Kernel.rand end
+  end
+  def Music.rng; @rng end
+  def Music.rng=(rng) @rng = rng end
+  Music.rng = RNG.new
+
+  def Music.rand; Music.rng.rand end
+
   class PitchClass
     include Comparable
 
@@ -125,6 +136,23 @@ def surface
     def structure
       StructureIterator.new(self)
     end
+
+    def include?(structure)
+      self == structure || has_next? && next_structure.include?(structure)
+    end
+
+    def splice(structure)
+      if has_next?
+        next_structure.splice(structure)
+      else
+        self >> structure
+      end
+    end
+
+    # Convenient access to the RNG
+    def rand
+      Music::rng.rand
+    end
   end
 
   class MusicEvent
@@ -140,13 +168,15 @@ class Surface
     include Enumerable
     extend Forwardable
 
-    def_delegators :@surface, :[], :[]=, :each, :first, :last
+    def_delegators :@surface, :[], :[]=, :each, :first, :last, :size, :length
 
     def initialize(head)
       @head, @surface = head, []
       generate
     end
 
+    def to_a; @surface end
+
     private
       def generate
         return if @head.nil?
@@ -168,6 +198,10 @@ def first; @head end
 
     def last; map { |s| s }[-1] end
 
+    def include?(structure)
+      detect { |s| s == structure } ? true : false
+    end
+
     def each
       return if @head.nil?
       cursor = @head
@@ -186,6 +220,13 @@ def initialize(duration)
       @duration = duration
     end
 
+    def ==(other)
+      case other
+        when Silence: @duration == other.duration
+        else false
+      end
+    end
+
     def perform(performance)
       performance.play_silence(self)
     end
@@ -199,6 +240,14 @@ def initialize(pitch, duration, effort)
       @pitch, @duration, @effort = pitch, duration, effort
     end
 
+    def ==(other)
+      case other
+        when Note
+          [@pitch, @duration, @effort] == [other.pitch, other.duration, other.effort]
+        else false
+      end
+    end
+
     def perform(performance)
       performance.play_note(self)
     end
@@ -219,6 +268,14 @@ def initialize(pitches, duration, effort)
       @pitches, @duration, @effort = pitches, duration, effort
     end
 
+    def ==(other)
+      case other
+        when Chord
+          [@pitches, @duration, @effort] == [other.pitches, other.duration, other.effort]
+        else false
+      end
+    end
+
     # Iterate over each pitch in the chord, with its corresponding effort value.
     def pitch_with_effort
       e = Array(effort)
@@ -234,7 +291,7 @@ def pitch_class
     end
 
     def transpose(hsteps, dur=self.duration, eff=self.effort)
-      self.class.new(pitch.map { |p| p+hsteps }, dur, eff)
+      self.class.new(pitches.map { |p| p+hsteps }, dur, eff)
     end
   end
 
@@ -252,7 +309,12 @@ def initialize(*args) # pitch, duration, effort
     end
 
     def generate(surface)
-      surface.last.transpose(*@args)
+      # Scan backwards for a transposable event.
+      if ev = surface.to_a.reverse.detect { |e| e.respond_to?(:transpose) }
+        ev.transpose(*@args)
+      else
+        Silence.new(0)
+      end
     end
   end
 
@@ -270,6 +332,14 @@ def activate
       end
       choice.activate
     end
+
+    def include?(structure)
+      self == structure || @choices.any? { |c| c.include?(structure) } || (has_next? && next_structure.include?(structure))
+    end
+
+    def splice(structure)
+      @choices.each { |c| c.splice(structure) unless c.include?(structure) }
+    end
   end
 
   class Cycle < MusicStructure
@@ -279,13 +349,20 @@ def initialize(*structures)
 
     def activate
       structure = @structures[next_index]
-      unless structure.has_next?
-        structure = structure.dup
-        structure >> @next
+      if has_next?
+        structure.structure.last >> @next unless structure.structure.include?(@next)
       end
       structure.activate
     end
 
+    def include?(structure)
+      self == structure || @structures.any? { |c| c.include?(structure) } || (has_next? && next_structure.include?(structure))
+    end
+
+    def splice(structure)
+      @structures.each { |c| c.splice(structure) unless c.include?(structure) }
+    end
+
     private
       def next_index
         @pos = (@pos + 1) % @structures.size
@@ -301,12 +378,21 @@ def initialize(repititions, structure)
 
     def activate
       if @repititions.zero?
-        @next.activate if @next
+        @next.activate if has_next?
       else
         @repititions -= 1
+        @structure.splice(self) unless @structure.include?(self)
         @structure.activate
       end
     end
+
+    def include?(structure)
+      self == structure || @structure.include?(structure) || (has_next? && next_structure.include?(structure))
+    end
+
+    def splice(structure)
+      @structure.splice(structure) unless @structure.include?(structure)
+    end
   end
 
   # Lifts a Proc into a MusicStructure.
@@ -355,6 +441,8 @@ def fun(&proc)
       Fun.new(&proc)
     end
 
+    def dupe; Dup.new end
+
     def seq(*structures)
       hd, *tl = structures
       tl.inject(hd) { |s, k| s.structure.last >> k }

spec/event_spec.rb

@@ -0,0 +1,117 @@
+require File.join( File.dirname(__FILE__), 'spec_helper')
+
+describe MusicEvent do
+
+  describe Silence do
+    before(:each) do
+      @event = Silence.new(1)
+    end
+
+    it "should have a duration" do
+      @event.duration.should == 1
+    end
+
+    it "can be performed" do
+      @event.should be_performed_with(:play_silence)
+    end
+  end
+
+  describe Note do
+    before(:each) do
+      @event = Note.new(60, 1, 127)
+    end
+
+    it "should have a pitch" do
+      @event.pitch.should == 60
+    end
+
+    it "should have a duration" do
+      @event.duration.should == 1
+    end
+
+    it "should have effort" do
+      @event.effort.should == 127
+    end
+
+    it "can be performed" do
+      @event.should be_performed_with(:play_note)
+    end
+
+    it "can be transposed" do
+      @event.transpose(2).should == Note.new(62, 1, 127)
+    end
+  end
+
+  describe Chord do
+    before(:each) do
+      @event = Chord.new([60, 64, 67], 1, 127)
+    end
+
+    it "should have a list of pitches" do
+      @event.pitches.should == [60, 64, 67]
+    end
+
+    it "should have a duration" do
+      @event.duration.should == 1
+    end
+
+    it "should have effort" do
+      @event.effort.should == 127
+    end
+
+    it "can enumerate its pitches with their respective efforts" do
+      data = []
+      @event.pitch_with_effort { |p, i| data << [p,i] }
+      data.should == [[60, 127], [64, 127], [67, 127]]
+    end
+
+    it "can have efforts specific to its pitches" do
+      chord = Chord.new([60, 64, 67], 1, [100, 110, 127])
+      data = []
+      chord.pitch_with_effort { |p, i| data << [p,i] }
+      data.should == [[60, 100], [64, 110], [67, 127]]
+    end
+
+    it "can be performed" do
+      @event.should be_performed_with(:play_chord)
+    end
+
+    it "can be transposed" do
+      @event.transpose(2).should == Chord.new([62, 66, 69], 1, 127)
+    end
+  end
+end
+
+class VisitorMatcher
+  class StubVisitor
+    def initialize(meth_sym)
+      @match = false
+      eval "def #{meth_sym}(*args) @match = true end"
+    end
+
+    def method_missing(meth_sym, *args)
+      @match = false
+      @__meth_sym = meth_sym
+    end
+
+    def __meth_sym; @__meth_sym.nil? ? "nothing" : @__meth_sym end
+
+    def __matches?; @match == true end
+  end
+
+  def initialize(meth_sym)
+    @visitor = StubVisitor.new(meth_sym)
+    @meth_sym = meth_sym
+  end
+
+  def matches?(ev)
+    ev.perform(@visitor)
+    @visitor.__matches?
+  end
+
+  def failure_message
+    "Expected visit with #@meth_sym. Got #{@visitor.__meth_sym}."
+  end
+end
+
+def be_performed_with(meth_sym) VisitorMatcher.new(meth_sym) end