Added blocks.executeExpression().

closes #154.

Author: Kanaye

src/query/Expression.js

@@ -8,6 +8,7 @@ define([
   var Expression = {
     Html: 0,
     ValueOnly: 2,
+    Raw: 3,
     NodeWise: 4,
 
     Create: function (text, attributeName, element) {
@@ -70,7 +71,7 @@ define([
 
     GetValue: function (context, elementData, expression, type) {
       var nodeWise = type == Expression.NodeWise;
-      var value = nodeWise ? [] : '';
+      var value = nodeWise || type == Expression.Raw ? [] : '';
       var length = expression.length;
       var index = -1;
       var chunk;
@@ -118,6 +119,8 @@ define([
 
           if (nodeWise) {
             value[expression.nodeLength - 1] = (value[expression.nodeLength - 1] || '') + tempValue;
+          } else if (type == Expression.Raw) {
+            value.push(tempValue);
           } else {
             value +=  tempValue;
           }
@@ -163,6 +166,10 @@ define([
 
       observables = Observer.stopObserving();
 
+      if (type == Expression.Raw) {
+        return {observables: observables, result: result, value: value};
+      }
+
       if (type != Expression.ValueOnly && type != Expression.NodeWise && (isObservable || observables.length)) {
         if (!attributeName) {
           elementData = ElementsData.createIfNotExists();

src/query/methods.js

@@ -6,8 +6,9 @@ define([
   './DomQuery',
   './VirtualElement',
   './ElementsData',
-  './serverData'
-], function (blocks, dataQueryAttr, OBSERVABLE, createVirtual, DomQuery, VirtualElement, ElementsData, serverData) {
+  './serverData',
+  './Expression'
+], function (blocks, dataQueryAttr, OBSERVABLE, createVirtual, DomQuery, VirtualElement, ElementsData, serverData, Expression) {
   /**
    * Performs a query operation on the DOM. Executes all data-query attributes
    * and renders the html result to the specified HTMLElement if not specified
@@ -175,4 +176,56 @@ define([
     }
     return null;
   };
+
+  /**
+   * Executes expressions on a specified context.
+   *
+   * @param  {string} expression The expression to execute.
+   * @param  {Object} context    The context to exute the expression on.
+   *                             The context for an element can be get via block.context().
+   * @param  {Object} [options]  An optional options objecz.
+   * @param  {bool}   [options.raw] If true the function returns an array with the raw value. Default: false
+   *
+   * @returns {string|Object[]}]  Returns the result of the expressions as a string.
+   *                             Or if options.raw is specified it returns an array of objects (see second example for details);
+   * @example {javascript}
+   * var context = {greeter: blocks.observable("world")};
+   * var expression = "Hello {{greeter}}!";
+   * blocks.executeExpression(expression, context);
+   * // -> "Hello world!"
+   *
+   * blocks.executeExpression(expression, context, {raw: true});
+   * // -> [{observables: [], value: "Hello ", result: "Hello "},
+   * //    {observables: [observable<"world">], value: observable<"world">, result: "world"},
+   * //    {observable: [], value: "!", result: "!"}]
+   */
+  blocks.executeExpression = function (expression, context, options) {
+    options = options || {};
+    var expressionData = Expression.Create(blocks.unwrapObservable(expression));
+    var setContext = false;
+    var value;
+    var values = [];
+    context = blocks.unwrapObservable(context);
+
+    if (!blocks.isObject(context)) {
+      context = {$this: context};
+    } else if (!context.$this) {
+      setContext = true;
+      context.$this = context;
+    }
+
+    value = Expression.GetValue(context, null, expressionData, options.raw ? Expression.Raw : Expression.ValueOnly);
+
+    if (setContext) {
+      context.$this = undefined;
+    }
+
+    if (options.raw) {
+      blocks.each(blocks.toArray(value), function (val, i) {
+        values[i] = blocks.isObject(val) ? val : {observables: [], result: val, value: val};
+      })
+    }
+
+    return options.raw ? values : value;
+  };
 });