Merge pull request #23 from PolymerLabs/set-value-justin

refactor NodePart::setValue

src/lit-html.ts

@@ -266,24 +266,12 @@ export class NodePart extends Part {
   }
 
   setValue(value: any): void {
-    let node: Node|undefined = undefined;
     value = this._getValue(value);
 
     if (value instanceof Node) {
-      this.clear();
-      node = value;
-      this._previousValue = value;
+      this._previousValue = this._setNodeValue(value);
     } else if (value instanceof TemplateResult) {
-      let instance: TemplateInstance;
-      if (this._previousValue && this._previousValue._template === value.template) {
-        instance = this._previousValue;
-      } else {
-        this.clear();
-        instance = this.instance._createInstance(value.template);
-        node = instance._clone();
-      }
-      instance.update(value.values);
-      this._previousValue = instance;
+      this._previousValue = this._setTemplateResultValue(value);
     } else if (value && value.then !== undefined) {
       value.then((v: any) => {
         if (this._previousValue === value) {
@@ -292,6 +280,44 @@ export class NodePart extends Part {
       });
       this._previousValue = value;
     } else if (value && typeof value !== 'string' && value[Symbol.iterator]) {
+      this._previousValue = this._setIterableValue(value);
+    } else if (this.startNode.nextSibling! === this.endNode.previousSibling! &&
+        this.startNode.nextSibling!.nodeType === Node.TEXT_NODE) {
+      this.startNode.nextSibling!.textContent = value;
+      this._previousValue = value;
+    } else {
+      this._previousValue = this._setTextValue(value);
+    }
+  }
+
+  private _insertNodeBeforeEndNode(node: Node) {
+    this.endNode.parentNode!.insertBefore(node, this.endNode);
+  }
+
+  private _setNodeValue(value: Node): Node {
+    this.clear();
+    this._insertNodeBeforeEndNode(value);
+
+    return value;
+  }
+
+  private _setTextValue(value: string): Node {
+    return this._setNodeValue(new Text(value));
+  }
+
+  private _setTemplateResultValue(value: TemplateResult): TemplateInstance {
+    let instance: TemplateInstance;
+    if (this._previousValue && this._previousValue._template === value.template) {
+      instance = this._previousValue;
+    } else {
+      instance = this.instance._createInstance(value.template);
+      this._setNodeValue(instance._clone());
+    }
+    instance.update(value.values);
+    return instance;
+  }
+
+  private _setIterableValue(value: any): NodePart[] {
     // For an Iterable, we create a new InstancePart per item, then set its
     // value to the item. This is a little bit of overhead for every item in
     // an Iterable, but it lets us recurse easily and update Arrays of
@@ -305,7 +331,8 @@ export class NodePart extends Part {
     let itemEnd;
     const values = value[Symbol.iterator]() as Iterator<any>;
 
-      const previousParts: NodePart[]|undefined = Array.isArray(this._previousValue) ? this._previousValue : undefined;
+    const previousParts: NodePart[]|undefined = Array.isArray(this._previousValue) ?
+        this._previousValue : undefined;
     let previousPartsIndex = 0;
     const itemParts = [];
     let current = values.next();
@@ -337,7 +364,7 @@ export class NodePart extends Part {
           itemEnd = this.endNode;
         } else {
           itemEnd = new Text();
-            this.endNode.parentNode!.insertBefore(itemEnd, this.endNode);
+          this._insertNodeBeforeEndNode(itemEnd);
         }
         itemPart = new NodePart(this.instance, itemStart, itemEnd);
       }
@@ -349,19 +376,7 @@ export class NodePart extends Part {
       next = values.next();
       itemStart = itemEnd;
     }
-      this._previousValue = itemParts;
-    } else if (this.startNode.nextSibling! === this.endNode.previousSibling! &&
-        this.startNode.nextSibling!.nodeType === Node.TEXT_NODE) {
-      this.startNode.nextSibling!.textContent = value;
-      this._previousValue = value;
-    } else {
-      this.clear();
-      node = new Text(value);
-      this._previousValue = value;
-    }
-    if (node !== undefined) {
-      this.endNode.parentNode!.insertBefore(node, this.endNode);
-    }
+    return itemParts;
   }
 
   clear(startNode: Node = this.startNode) {