Merge pull request #8 from theSherwood/subscription

Adds subscriptions to variables

Author: trusktr

dist/variable.d.ts

@@ -45,6 +45,17 @@ export declare class Variable {
      * @private
      */
     setValue(value: number): void;
+    /**
+     * Set a callback for whenever the value changes.
+     *
+     * @param {function(number,number):void} callback to call whenever the variable value changes
+     */
+    subscribe(callback: (value: number, previousValue: number) => void): void;
+    /**
+     * Stops the variable from calling the callback when the variable value
+     * changes.
+     */
+    unsubscribe(): void;
     /**
      * Creates a new Expression by adding a number, variable or expression
      * to the variable.
@@ -85,5 +96,6 @@ export declare class Variable {
     private _value;
     private _context;
     private _id;
+    private _callback;
 }
 //# sourceMappingURL=variable.d.ts.map

dist/variable.d.ts.map

@@ -59,7 +59,26 @@ export class Variable {
      * @private
      */
     setValue(value) {
+        var previousValue = this._value;
         this._value = value;
+        if (this._callback && previousValue !== value) {
+            this._callback(value, previousValue);
+        }
+    }
+    /**
+     * Set a callback for whenever the value changes.
+     *
+     * @param {function(number,number):void} callback to call whenever the variable value changes
+     */
+    subscribe(callback) {
+        this._callback = callback;
+    }
+    /**
+     * Stops the variable from calling the callback when the variable value
+     * changes.
+     */
+    unsubscribe() {
+        this._callback = null;
     }
     /**
      * Creates a new Expression by adding a number, variable or expression
@@ -116,6 +135,7 @@ export class Variable {
     _value = 0.0;
     _context = null;
     _id = VarId++;
+    _callback;
 }
 /**
  * The internal variable id counter.

dist/variable.js

@@ -48,6 +48,8 @@ console.assert(centerX.value() === 250)
     - [.name()](#module_@lume/kiwi..Variable+name) ⇒ <code>String</code>
     - [.setName(name)](#module_@lume/kiwi..Variable+setName)
     - [.value()](#module_@lume/kiwi..Variable+value) ⇒ <code>Number</code>
+    - [.subscribe(callback)](#module_@lume/kiwi..Variable+subscribe)
+    - [.unsubscribe()](#module_@lume/kiwi..Variable+unsubscribe)
     - [.plus(value)](#module_@lume/kiwi..Variable+plus) ⇒ <code>Expression</code>
     - [.minus(value)](#module_@lume/kiwi..Variable+minus) ⇒ <code>Expression</code>
     - [.multiply(coefficient)](#module_@lume/kiwi..Variable+multiply) ⇒ <code>Expression</code>
@@ -99,6 +101,8 @@ The primary user constraint variable.
   - [.name()](#module_@lume/kiwi..Variable+name) ⇒ <code>String</code>
   - [.setName(name)](#module_@lume/kiwi..Variable+setName)
   - [.value()](#module_@lume/kiwi..Variable+value) ⇒ <code>Number</code>
+  - [.subscribe(callback)](#module_@lume/kiwi..Variable+subscribe)
+  - [.unsubscribe()](#module_@lume/kiwi..Variable+unsubscribe)
   - [.plus(value)](#module_@lume/kiwi..Variable+plus) ⇒ <code>Expression</code>
   - [.minus(value)](#module_@lume/kiwi..Variable+minus) ⇒ <code>Expression</code>
   - [.multiply(coefficient)](#module_@lume/kiwi..Variable+multiply) ⇒ <code>Expression</code>
@@ -140,6 +144,26 @@ Returns the value of the variable.
 
 **Kind**: instance method of [<code>Variable</code>](#module_@lume/kiwi..Variable)  
 **Returns**: <code>Number</code> - Calculated value  
+<a name="module_@lume/kiwi..Variable+subscribe"></a>
+
+### variable.subscribe(callback)
+
+Set a callback for whenever the value changes.
+
+**Kind**: instance method of [<code>Variable</code>](#module_@lume/kiwi..Variable)
+
+| Param    | Type                  | Description                                 |
+| -------- | --------------------- | ------------------------------------------- |
+| callback | <code>function</code> | to call whenever the variable value changes |
+
+<a name="module_@lume/kiwi..Variable+unsubscribe"></a>
+
+### variable.unsubscribe()
+
+Stops the variable from calling the callback when the variable value
+changes.
+
+**Kind**: instance method of [<code>Variable</code>](#module_@lume/kiwi..Variable)  
 <a name="module_@lume/kiwi..Variable+plus"></a>
 
 ### variable.plus(value) ⇒ <code>Expression</code>

docs/Kiwi.md

@@ -67,7 +67,28 @@ export class Variable {
 	 * @private
 	 */
 	public setValue(value: number): void {
+		var previousValue = this._value
 		this._value = value
+		if (this._callback && previousValue !== value) {
+			this._callback(value, previousValue)
+		}
+	}
+
+	/**
+	 * Set a callback for whenever the value changes.
+	 *
+	 * @param {function(number,number):void} callback to call whenever the variable value changes
+	 */
+	public subscribe(callback: (value: number, previousValue: number) => void): void {
+		this._callback = callback
+	}
+
+	/**
+	 * Stops the variable from calling the callback when the variable value
+	 * changes.
+	 */
+	public unsubscribe(): void {
+		this._callback = null
 	}
 
 	/**
@@ -131,6 +152,7 @@ export class Variable {
 	private _value: number = 0.0
 	private _context: any = null
 	private _id: number = VarId++
+	private _callback: (value: number, previousValue: number) => void
 }
 
 /**

src/variable.ts

@@ -39,6 +39,33 @@ describe('import kiwi', function () {
 				solver.updateVariables()
 				assert.equal(200, variable.value())
 			})
+			it('variable.subscribe(callback) => value: 400', function () {
+				var var2 = new kiwi.Variable()
+				var val, previousVal
+				var2.subscribe((value, previousValue) => ((val = value), (previousVal = previousValue)))
+				assert.equal(val, undefined)
+				assert.equal(previousVal, undefined)
+				solver.addEditVariable(var2, kiwi.Strength.strong)
+				solver.suggestValue(var2, 400)
+				solver.updateVariables()
+				assert.equal(val, 400)
+				assert.equal(previousVal, 0)
+				solver.suggestValue(var2, 500)
+				solver.updateVariables()
+				assert.equal(val, 500)
+				assert.equal(previousVal, 400)
+			})
+			it('variable.unsubscribe()', function () {
+				var var2 = new kiwi.Variable()
+				var val, previousVal
+				var2.subscribe((value, previousValue) => ((val = value), (previousVal = previousValue)))
+				solver.addEditVariable(var2, kiwi.Strength.strong)
+				solver.suggestValue(var2, 300)
+				var2.unsubscribe()
+				solver.updateVariables()
+				assert.equal(val, undefined)
+				assert.equal(previousVal, undefined)
+			})
 			it('solver.removeEditVariable(variable) => solver.hasEditVariable(): false', function () {
 				assert(solver.hasEditVariable(variable))
 				solver.removeEditVariable(variable)