michael@0: /*
michael@0:  * Copyright 2012, Mozilla Foundation and contributors
michael@0:  *
michael@0:  * Licensed under the Apache License, Version 2.0 (the "License");
michael@0:  * you may not use this file except in compliance with the License.
michael@0:  * You may obtain a copy of the License at
michael@0:  *
michael@0:  * http://www.apache.org/licenses/LICENSE-2.0
michael@0:  *
michael@0:  * Unless required by applicable law or agreed to in writing, software
michael@0:  * distributed under the License is distributed on an "AS IS" BASIS,
michael@0:  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
michael@0:  * See the License for the specific language governing permissions and
michael@0:  * limitations under the License.
michael@0:  */
michael@0: 
michael@0: this.EXPORTED_SYMBOLS = [ "template" ];
michael@0: Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
michael@0: XPCOMUtils.defineLazyModuleGetter(this, "console",
michael@0:                                   "resource://gre/modules/devtools/Console.jsm");
michael@0: 
michael@0: 'do not use strict';
michael@0: 
michael@0: // WARNING: do not 'use strict' without reading the notes in envEval();
michael@0: // Also don't remove the 'do not use strict' marker. The orion build uses these
michael@0: // markers to know where to insert AMD headers.
michael@0: 
michael@0: /**
michael@0:  * For full documentation, see:
michael@0:  * https://github.com/mozilla/domtemplate/blob/master/README.md
michael@0:  */
michael@0: 
michael@0: /**
michael@0:  * Begin a new templating process.
michael@0:  * @param node A DOM element or string referring to an element's id
michael@0:  * @param data Data to use in filling out the template
michael@0:  * @param options Options to customize the template processing. One of:
michael@0:  * - allowEval: boolean (default false) Basic template interpolations are
michael@0:  *   either property paths (e.g. ${a.b.c.d}), or if allowEval=true then we
michael@0:  *   allow arbitrary JavaScript
michael@0:  * - stack: string or array of strings (default empty array) The template
michael@0:  *   engine maintains a stack of tasks to help debug where it is. This allows
michael@0:  *   this stack to be prefixed with a template name
michael@0:  * - blankNullUndefined: By default DOMTemplate exports null and undefined
michael@0:  *   values using the strings 'null' and 'undefined', which can be helpful for
michael@0:  *   debugging, but can introduce unnecessary extra logic in a template to
michael@0:  *   convert null/undefined to ''. By setting blankNullUndefined:true, this
michael@0:  *   conversion is handled by DOMTemplate
michael@0:  */
michael@0: var template = function(node, data, options) {
michael@0:   var state = {
michael@0:     options: options || {},
michael@0:     // We keep a track of the nodes that we've passed through so we can keep
michael@0:     // data.__element pointing to the correct node
michael@0:     nodes: []
michael@0:   };
michael@0: 
michael@0:   state.stack = state.options.stack;
michael@0: 
michael@0:   if (!Array.isArray(state.stack)) {
michael@0:     if (typeof state.stack === 'string') {
michael@0:       state.stack = [ options.stack ];
michael@0:     }
michael@0:     else {
michael@0:       state.stack = [];
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   processNode(state, node, data);
michael@0: };
michael@0: 
michael@0: //
michael@0: //
michael@0: //
michael@0: 
michael@0: /**
michael@0:  * Helper for the places where we need to act asynchronously and keep track of
michael@0:  * where we are right now
michael@0:  */
michael@0: function cloneState(state) {
michael@0:   return {
michael@0:     options: state.options,
michael@0:     stack: state.stack.slice(),
michael@0:     nodes: state.nodes.slice()
michael@0:   };
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Regex used to find ${...} sections in some text.
michael@0:  * Performance note: This regex uses ( and ) to capture the 'script' for
michael@0:  * further processing. Not all of the uses of this regex use this feature so
michael@0:  * if use of the capturing group is a performance drain then we should split
michael@0:  * this regex in two.
michael@0:  */
michael@0: var TEMPLATE_REGION = /\$\{([^}]*)\}/g;
michael@0: 
michael@0: /**
michael@0:  * Recursive function to walk the tree processing the attributes as it goes.
michael@0:  * @param node the node to process. If you pass a string in instead of a DOM
michael@0:  * element, it is assumed to be an id for use with document.getElementById()
michael@0:  * @param data the data to use for node processing.
michael@0:  */
michael@0: function processNode(state, node, data) {
michael@0:   if (typeof node === 'string') {
michael@0:     node = document.getElementById(node);
michael@0:   }
michael@0:   if (data == null) {
michael@0:     data = {};
michael@0:   }
michael@0:   state.stack.push(node.nodeName + (node.id ? '#' + node.id : ''));
michael@0:   var pushedNode = false;
michael@0:   try {
michael@0:     // Process attributes
michael@0:     if (node.attributes && node.attributes.length) {
michael@0:       // We need to handle 'foreach' and 'if' first because they might stop
michael@0:       // some types of processing from happening, and foreach must come first
michael@0:       // because it defines new data on which 'if' might depend.
michael@0:       if (node.hasAttribute('foreach')) {
michael@0:         processForEach(state, node, data);
michael@0:         return;
michael@0:       }
michael@0:       if (node.hasAttribute('if')) {
michael@0:         if (!processIf(state, node, data)) {
michael@0:           return;
michael@0:         }
michael@0:       }
michael@0:       // Only make the node available once we know it's not going away
michael@0:       state.nodes.push(data.__element);
michael@0:       data.__element = node;
michael@0:       pushedNode = true;
michael@0:       // It's good to clean up the attributes when we've processed them,
michael@0:       // but if we do it straight away, we mess up the array index
michael@0:       var attrs = Array.prototype.slice.call(node.attributes);
michael@0:       for (var i = 0; i < attrs.length; i++) {
michael@0:         var value = attrs[i].value;
michael@0:         var name = attrs[i].name;
michael@0: 
michael@0:         state.stack.push(name);
michael@0:         try {
michael@0:           if (name === 'save') {
michael@0:             // Save attributes are a setter using the node
michael@0:             value = stripBraces(state, value);
michael@0:             property(state, value, data, node);
michael@0:             node.removeAttribute('save');
michael@0:           }
michael@0:           else if (name.substring(0, 2) === 'on') {
michael@0:             // If this attribute value contains only an expression
michael@0:             if (value.substring(0, 2) === '${' && value.slice(-1) === '}' &&
michael@0:                     value.indexOf('${', 2) === -1) {
michael@0:               value = stripBraces(state, value);
michael@0:               var func = property(state, value, data);
michael@0:               if (typeof func === 'function') {
michael@0:                 node.removeAttribute(name);
michael@0:                 var capture = node.hasAttribute('capture' + name.substring(2));
michael@0:                 node.addEventListener(name.substring(2), func, capture);
michael@0:                 if (capture) {
michael@0:                   node.removeAttribute('capture' + name.substring(2));
michael@0:                 }
michael@0:               }
michael@0:               else {
michael@0:                 // Attribute value is not a function - use as a DOM-L0 string
michael@0:                 node.setAttribute(name, func);
michael@0:               }
michael@0:             }
michael@0:             else {
michael@0:               // Attribute value is not a single expression use as DOM-L0
michael@0:               node.setAttribute(name, processString(state, value, data));
michael@0:             }
michael@0:           }
michael@0:           else {
michael@0:             node.removeAttribute(name);
michael@0:             // Remove '_' prefix of attribute names so the DOM won't try
michael@0:             // to use them before we've processed the template
michael@0:             if (name.charAt(0) === '_') {
michael@0:               name = name.substring(1);
michael@0:             }
michael@0: 
michael@0:             // Async attributes can only work if the whole attribute is async
michael@0:             var replacement;
michael@0:             if (value.indexOf('${') === 0 &&
michael@0:                 value.charAt(value.length - 1) === '}') {
michael@0:               replacement = envEval(state, value.slice(2, -1), data, value);
michael@0:               if (replacement && typeof replacement.then === 'function') {
michael@0:                 node.setAttribute(name, '');
michael@0:                 replacement.then(function(newValue) {
michael@0:                   node.setAttribute(name, newValue);
michael@0:                 }).then(null, console.error);
michael@0:               }
michael@0:               else {
michael@0:                 if (state.options.blankNullUndefined && replacement == null) {
michael@0:                   replacement = '';
michael@0:                 }
michael@0:                 node.setAttribute(name, replacement);
michael@0:               }
michael@0:             }
michael@0:             else {
michael@0:               node.setAttribute(name, processString(state, value, data));
michael@0:             }
michael@0:           }
michael@0:         }
michael@0:         finally {
michael@0:           state.stack.pop();
michael@0:         }
michael@0:       }
michael@0:     }
michael@0: 
michael@0:     // Loop through our children calling processNode. First clone them, so the
michael@0:     // set of nodes that we visit will be unaffected by additions or removals.
michael@0:     var childNodes = Array.prototype.slice.call(node.childNodes);
michael@0:     for (var j = 0; j < childNodes.length; j++) {
michael@0:       processNode(state, childNodes[j], data);
michael@0:     }
michael@0: 
michael@0:     if (node.nodeType === 3 /*Node.TEXT_NODE*/) {
michael@0:       processTextNode(state, node, data);
michael@0:     }
michael@0:   }
michael@0:   finally {
michael@0:     if (pushedNode) {
michael@0:       data.__element = state.nodes.pop();
michael@0:     }
michael@0:     state.stack.pop();
michael@0:   }
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Handle attribute values where the output can only be a string
michael@0:  */
michael@0: function processString(state, value, data) {
michael@0:   return value.replace(TEMPLATE_REGION, function(path) {
michael@0:     var insert = envEval(state, path.slice(2, -1), data, value);
michael@0:     return state.options.blankNullUndefined && insert == null ? '' : insert;
michael@0:   });
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Handle <x if="${...}">
michael@0:  * @param node An element with an 'if' attribute
michael@0:  * @param data The data to use with envEval()
michael@0:  * @returns true if processing should continue, false otherwise
michael@0:  */
michael@0: function processIf(state, node, data) {
michael@0:   state.stack.push('if');
michael@0:   try {
michael@0:     var originalValue = node.getAttribute('if');
michael@0:     var value = stripBraces(state, originalValue);
michael@0:     var recurse = true;
michael@0:     try {
michael@0:       var reply = envEval(state, value, data, originalValue);
michael@0:       recurse = !!reply;
michael@0:     }
michael@0:     catch (ex) {
michael@0:       handleError(state, 'Error with \'' + value + '\'', ex);
michael@0:       recurse = false;
michael@0:     }
michael@0:     if (!recurse) {
michael@0:       node.parentNode.removeChild(node);
michael@0:     }
michael@0:     node.removeAttribute('if');
michael@0:     return recurse;
michael@0:   }
michael@0:   finally {
michael@0:     state.stack.pop();
michael@0:   }
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Handle <x foreach="param in ${array}"> and the special case of
michael@0:  * <loop foreach="param in ${array}">.
michael@0:  * This function is responsible for extracting what it has to do from the
michael@0:  * attributes, and getting the data to work on (including resolving promises
michael@0:  * in getting the array). It delegates to processForEachLoop to actually
michael@0:  * unroll the data.
michael@0:  * @param node An element with a 'foreach' attribute
michael@0:  * @param data The data to use with envEval()
michael@0:  */
michael@0: function processForEach(state, node, data) {
michael@0:   state.stack.push('foreach');
michael@0:   try {
michael@0:     var originalValue = node.getAttribute('foreach');
michael@0:     var value = originalValue;
michael@0: 
michael@0:     var paramName = 'param';
michael@0:     if (value.charAt(0) === '$') {
michael@0:       // No custom loop variable name. Use the default: 'param'
michael@0:       value = stripBraces(state, value);
michael@0:     }
michael@0:     else {
michael@0:       // Extract the loop variable name from 'NAME in ${ARRAY}'
michael@0:       var nameArr = value.split(' in ');
michael@0:       paramName = nameArr[0].trim();
michael@0:       value = stripBraces(state, nameArr[1].trim());
michael@0:     }
michael@0:     node.removeAttribute('foreach');
michael@0:     try {
michael@0:       var evaled = envEval(state, value, data, originalValue);
michael@0:       var cState = cloneState(state);
michael@0:       handleAsync(evaled, node, function(reply, siblingNode) {
michael@0:         processForEachLoop(cState, reply, node, siblingNode, data, paramName);
michael@0:       });
michael@0:       node.parentNode.removeChild(node);
michael@0:     }
michael@0:     catch (ex) {
michael@0:       handleError(state, 'Error with \'' + value + '\'', ex);
michael@0:     }
michael@0:   }
michael@0:   finally {
michael@0:     state.stack.pop();
michael@0:   }
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Called by processForEach to handle looping over the data in a foreach loop.
michael@0:  * This works with both arrays and objects.
michael@0:  * Calls processForEachMember() for each member of 'set'
michael@0:  * @param set The object containing the data to loop over
michael@0:  * @param templNode The node to copy for each set member
michael@0:  * @param sibling The sibling node to which we add things
michael@0:  * @param data the data to use for node processing
michael@0:  * @param paramName foreach loops have a name for the parameter currently being
michael@0:  * processed. The default is 'param'. e.g. <loop foreach="param in ${x}">...
michael@0:  */
michael@0: function processForEachLoop(state, set, templNode, sibling, data, paramName) {
michael@0:   if (Array.isArray(set)) {
michael@0:     set.forEach(function(member, i) {
michael@0:       processForEachMember(state, member, templNode, sibling,
michael@0:                            data, paramName, '' + i);
michael@0:     });
michael@0:   }
michael@0:   else {
michael@0:     for (var member in set) {
michael@0:       if (set.hasOwnProperty(member)) {
michael@0:         processForEachMember(state, member, templNode, sibling,
michael@0:                              data, paramName, member);
michael@0:       }
michael@0:     }
michael@0:   }
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Called by processForEachLoop() to resolve any promises in the array (the
michael@0:  * array itself can also be a promise, but that is resolved by
michael@0:  * processForEach()). Handle <LOOP> elements (which are taken out of the DOM),
michael@0:  * clone the template node, and pass the processing on to processNode().
michael@0:  * @param member The data item to use in templating
michael@0:  * @param templNode The node to copy for each set member
michael@0:  * @param siblingNode The parent node to which we add things
michael@0:  * @param data the data to use for node processing
michael@0:  * @param paramName The name given to 'member' by the foreach attribute
michael@0:  * @param frame A name to push on the stack for debugging
michael@0:  */
michael@0: function processForEachMember(state, member, templNode, siblingNode, data, paramName, frame) {
michael@0:   state.stack.push(frame);
michael@0:   try {
michael@0:     var cState = cloneState(state);
michael@0:     handleAsync(member, siblingNode, function(reply, node) {
michael@0:       data[paramName] = reply;
michael@0:       if (node.parentNode != null) {
michael@0:         if (templNode.nodeName.toLowerCase() === 'loop') {
michael@0:           for (var i = 0; i < templNode.childNodes.length; i++) {
michael@0:             var clone = templNode.childNodes[i].cloneNode(true);
michael@0:             node.parentNode.insertBefore(clone, node);
michael@0:             processNode(cState, clone, data);
michael@0:           }
michael@0:         }
michael@0:         else {
michael@0:           var clone = templNode.cloneNode(true);
michael@0:           clone.removeAttribute('foreach');
michael@0:           node.parentNode.insertBefore(clone, node);
michael@0:           processNode(cState, clone, data);
michael@0:         }
michael@0:       }
michael@0:       delete data[paramName];
michael@0:     });
michael@0:   }
michael@0:   finally {
michael@0:     state.stack.pop();
michael@0:   }
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Take a text node and replace it with another text node with the ${...}
michael@0:  * sections parsed out. We replace the node by altering node.parentNode but
michael@0:  * we could probably use a DOM Text API to achieve the same thing.
michael@0:  * @param node The Text node to work on
michael@0:  * @param data The data to use in calls to envEval()
michael@0:  */
michael@0: function processTextNode(state, node, data) {
michael@0:   // Replace references in other attributes
michael@0:   var value = node.data;
michael@0:   // We can't use the string.replace() with function trick (see generic
michael@0:   // attribute processing in processNode()) because we need to support
michael@0:   // functions that return DOM nodes, so we can't have the conversion to a
michael@0:   // string.
michael@0:   // Instead we process the string as an array of parts. In order to split
michael@0:   // the string up, we first replace '${' with '\uF001$' and '}' with '\uF002'
michael@0:   // We can then split using \uF001 or \uF002 to get an array of strings
michael@0:   // where scripts are prefixed with $.
michael@0:   // \uF001 and \uF002 are just unicode chars reserved for private use.
michael@0:   value = value.replace(TEMPLATE_REGION, '\uF001$$$1\uF002');
michael@0:   // Split a string using the unicode chars F001 and F002.
michael@0:   var parts = value.split(/\uF001|\uF002/);
michael@0:   if (parts.length > 1) {
michael@0:     parts.forEach(function(part) {
michael@0:       if (part === null || part === undefined || part === '') {
michael@0:         return;
michael@0:       }
michael@0:       if (part.charAt(0) === '$') {
michael@0:         part = envEval(state, part.slice(1), data, node.data);
michael@0:       }
michael@0:       var cState = cloneState(state);
michael@0:       handleAsync(part, node, function(reply, siblingNode) {
michael@0:         var doc = siblingNode.ownerDocument;
michael@0:         if (reply == null) {
michael@0:           reply = cState.options.blankNullUndefined ? '' : '' + reply;
michael@0:         }
michael@0:         if (typeof reply.cloneNode === 'function') {
michael@0:           // i.e. if (reply instanceof Element) { ...
michael@0:           reply = maybeImportNode(cState, reply, doc);
michael@0:           siblingNode.parentNode.insertBefore(reply, siblingNode);
michael@0:         }
michael@0:         else if (typeof reply.item === 'function' && reply.length) {
michael@0:           // NodeLists can be live, in which case maybeImportNode can
michael@0:           // remove them from the document, and thus the NodeList, which in
michael@0:           // turn breaks iteration. So first we clone the list
michael@0:           var list = Array.prototype.slice.call(reply, 0);
michael@0:           list.forEach(function(child) {
michael@0:             var imported = maybeImportNode(cState, child, doc);
michael@0:             siblingNode.parentNode.insertBefore(imported, siblingNode);
michael@0:           });
michael@0:         }
michael@0:         else {
michael@0:           // if thing isn't a DOM element then wrap its string value in one
michael@0:           reply = doc.createTextNode(reply.toString());
michael@0:           siblingNode.parentNode.insertBefore(reply, siblingNode);
michael@0:         }
michael@0:       });
michael@0:     });
michael@0:     node.parentNode.removeChild(node);
michael@0:   }
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Return node or a import of node, if it's not in the given document
michael@0:  * @param node The node that we want to be properly owned
michael@0:  * @param doc The document that the given node should belong to
michael@0:  * @return A node that belongs to the given document
michael@0:  */
michael@0: function maybeImportNode(state, node, doc) {
michael@0:   return node.ownerDocument === doc ? node : doc.importNode(node, true);
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * A function to handle the fact that some nodes can be promises, so we check
michael@0:  * and resolve if needed using a marker node to keep our place before calling
michael@0:  * an inserter function.
michael@0:  * @param thing The object which could be real data or a promise of real data
michael@0:  * we use it directly if it's not a promise, or resolve it if it is.
michael@0:  * @param siblingNode The element before which we insert new elements.
michael@0:  * @param inserter The function to to the insertion. If thing is not a promise
michael@0:  * then handleAsync() is just 'inserter(thing, siblingNode)'
michael@0:  */
michael@0: function handleAsync(thing, siblingNode, inserter) {
michael@0:   if (thing != null && typeof thing.then === 'function') {
michael@0:     // Placeholder element to be replaced once we have the real data
michael@0:     var tempNode = siblingNode.ownerDocument.createElement('span');
michael@0:     siblingNode.parentNode.insertBefore(tempNode, siblingNode);
michael@0:     thing.then(function(delayed) {
michael@0:       inserter(delayed, tempNode);
michael@0:       if (tempNode.parentNode != null) {
michael@0:         tempNode.parentNode.removeChild(tempNode);
michael@0:       }
michael@0:     }).then(null, function(error) {
michael@0:       console.error(error.stack);
michael@0:     });
michael@0:   }
michael@0:   else {
michael@0:     inserter(thing, siblingNode);
michael@0:   }
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Warn of string does not begin '${' and end '}'
michael@0:  * @param str the string to check.
michael@0:  * @return The string stripped of ${ and }, or untouched if it does not match
michael@0:  */
michael@0: function stripBraces(state, str) {
michael@0:   if (!str.match(TEMPLATE_REGION)) {
michael@0:     handleError(state, 'Expected ' + str + ' to match ${...}');
michael@0:     return str;
michael@0:   }
michael@0:   return str.slice(2, -1);
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Combined getter and setter that works with a path through some data set.
michael@0:  * For example:
michael@0:  * <ul>
michael@0:  * <li>property(state, 'a.b', { a: { b: 99 }}); // returns 99
michael@0:  * <li>property(state, 'a', { a: { b: 99 }}); // returns { b: 99 }
michael@0:  * <li>property(state, 'a', { a: { b: 99 }}, 42); // returns 99 and alters the
michael@0:  * input data to be { a: { b: 42 }}
michael@0:  * </ul>
michael@0:  * @param path An array of strings indicating the path through the data, or
michael@0:  * a string to be cut into an array using <tt>split('.')</tt>
michael@0:  * @param data the data to use for node processing
michael@0:  * @param newValue (optional) If defined, this value will replace the
michael@0:  * original value for the data at the path specified.
michael@0:  * @return The value pointed to by <tt>path</tt> before any
michael@0:  * <tt>newValue</tt> is applied.
michael@0:  */
michael@0: function property(state, path, data, newValue) {
michael@0:   try {
michael@0:     if (typeof path === 'string') {
michael@0:       path = path.split('.');
michael@0:     }
michael@0:     var value = data[path[0]];
michael@0:     if (path.length === 1) {
michael@0:       if (newValue !== undefined) {
michael@0:         data[path[0]] = newValue;
michael@0:       }
michael@0:       if (typeof value === 'function') {
michael@0:         return value.bind(data);
michael@0:       }
michael@0:       return value;
michael@0:     }
michael@0:     if (!value) {
michael@0:       handleError(state, '"' + path[0] + '" is undefined');
michael@0:       return null;
michael@0:     }
michael@0:     return property(state, path.slice(1), value, newValue);
michael@0:   }
michael@0:   catch (ex) {
michael@0:     handleError(state, 'Path error with \'' + path + '\'', ex);
michael@0:     return '${' + path + '}';
michael@0:   }
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Like eval, but that creates a context of the variables in <tt>env</tt> in
michael@0:  * which the script is evaluated.
michael@0:  * WARNING: This script uses 'with' which is generally regarded to be evil.
michael@0:  * The alternative is to create a Function at runtime that takes X parameters
michael@0:  * according to the X keys in the env object, and then call that function using
michael@0:  * the values in the env object. This is likely to be slow, but workable.
michael@0:  * @param script The string to be evaluated.
michael@0:  * @param data The environment in which to eval the script.
michael@0:  * @param frame Optional debugging string in case of failure.
michael@0:  * @return The return value of the script, or the error message if the script
michael@0:  * execution failed.
michael@0:  */
michael@0: function envEval(state, script, data, frame) {
michael@0:   try {
michael@0:     state.stack.push(frame.replace(/\s+/g, ' '));
michael@0:     // Detect if a script is capable of being interpreted using property()
michael@0:     if (/^[_a-zA-Z0-9.]*$/.test(script)) {
michael@0:       return property(state, script, data);
michael@0:     }
michael@0:     else {
michael@0:       if (!state.options.allowEval) {
michael@0:         handleError(state, 'allowEval is not set, however \'' + script + '\'' +
michael@0:             ' can not be resolved using a simple property path.');
michael@0:         return '${' + script + '}';
michael@0:       }
michael@0:       with (data) {
michael@0:         return eval(script);
michael@0:       }
michael@0:     }
michael@0:   }
michael@0:   catch (ex) {
michael@0:     handleError(state, 'Template error evaluating \'' + script + '\'', ex);
michael@0:     return '${' + script + '}';
michael@0:   }
michael@0:   finally {
michael@0:     state.stack.pop();
michael@0:   }
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * A generic way of reporting errors, for easy overloading in different
michael@0:  * environments.
michael@0:  * @param message the error message to report.
michael@0:  * @param ex optional associated exception.
michael@0:  */
michael@0: function handleError(state, message, ex) {
michael@0:   logError(message + ' (In: ' + state.stack.join(' > ') + ')');
michael@0:   if (ex) {
michael@0:     logError(ex);
michael@0:   }
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * A generic way of reporting errors, for easy overloading in different
michael@0:  * environments.
michael@0:  * @param message the error message to report.
michael@0:  */
michael@0: function logError(message) {
michael@0:   console.log(message);
michael@0: }