From e5a6788de1fce0d11d147aa465ddc7e5f1acaacc Mon Sep 17 00:00:00 2001
From: Yotam Mann <yotammann@gmail.com>
Date: Thu, 1 Mar 2018 14:11:07 -0500
Subject: [PATCH] getNextState returns the next instance of the given state
 after the given time

---
 Tone/core/TimelineState.js | 19 +++++++++++++++++++
 test/core/TimelineState.js | 16 ++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/Tone/core/TimelineState.js b/Tone/core/TimelineState.js
index da5d3a20..f5f09843 100644
--- a/Tone/core/TimelineState.js
+++ b/Tone/core/TimelineState.js
@@ -46,6 +46,8 @@ define(["Tone/core/Tone", "Tone/core/Timeline", "Tone/type/Type"], function(Tone
 	 *  @returns {Tone.TimelineState} this
 	 */
 	Tone.TimelineState.prototype.setStateAtTime = function(state, time){
+		//all state changes need to be >= the previous state time
+		//TODO throw error if time < the previous event time
 		this.add({
 			"state" : state,
 			"time" : time
@@ -70,5 +72,22 @@ define(["Tone/core/Tone", "Tone/core/Timeline", "Tone/type/Type"], function(Tone
 		}
 	};
 
+	/**
+	 *  Return the event after the time with the given state
+	 *  @param {Tone.State} state The state to look for
+	 *  @param  {Time}  time  When to check from
+	 *  @return  {Object}  The event with the given state after the time
+	 */
+	Tone.TimelineState.prototype.getNextState = function(state, time){
+		time = this.toSeconds(time);
+		var index = this._search(time);
+		for (var i = index; i < this._timeline.length; i++){
+			var event = this._timeline[i];
+			if (event.state === state){
+				return event;
+			}
+		}
+	};
+
 	return Tone.TimelineState;
 });
diff --git a/test/core/TimelineState.js b/test/core/TimelineState.js
index 726dfea6..b6c2e5d7 100644
--- a/test/core/TimelineState.js
+++ b/test/core/TimelineState.js
@@ -61,5 +61,21 @@ define(["Test", "Tone/core/TimelineState"], function(Test, TimelineState) {
 			sched.dispose();
 		});
 		
+		it("gets the next occurance of the state at or before the given time", function(){
+			var sched = new TimelineState();
+			sched.setStateAtTime("A", 0);
+			sched.setStateAtTime("B", 1);
+			sched.setStateAtTime("C", 2);
+			sched.setStateAtTime("B", 3);
+			expect(sched.getNextState("B", 1)).exists;
+			expect(sched.getNextState("B", 1).state).is.equal("B");
+			expect(sched.getNextState("B", 2)).exists;
+			expect(sched.getNextState("B", 2).state).is.equal("B");
+			expect(sched.getNextState("B", 2).time).is.equal(3);
+			expect(sched.getNextState("B", 0.9)).exists;
+			expect(sched.getNextState("B", 0.9).state).is.equal("B");
+			expect(sched.getNextState("B", 0.9).time).is.equal(1);
+			sched.dispose();
+		});
 	});
 });