Add a benchmark extension.

chrome/test/data/extensions/samples/benchmark/jst/jstemplate.js

+// Copyright 2006 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+// implied. See the License for the specific language governing
+// permissions and limitations under the License.
+/**
+ * Author: Steffen Meschkat <mesch@google.com>
+ *
+ * @fileoverview A simple formatter to project JavaScript data into
+ * HTML templates. The template is edited in place. I.e. in order to
+ * instantiate a template, clone it from the DOM first, and then
+ * process the cloned template. This allows for updating of templates:
+ * If the templates is processed again, changed values are merely
+ * updated.
+ *
+ * NOTE(mesch): IE DOM doesn't have importNode().
+ *
+ * NOTE(mesch): The property name "length" must not be used in input
+ * data, see comment in jstSelect_().
+ */
+
+
+/**
+ * Names of jstemplate attributes. These attributes are attached to
+ * normal HTML elements and bind expression context data to the HTML
+ * fragment that is used as template.
+ */
+var ATT_select = 'jsselect';
+var ATT_instance = 'jsinstance';
+var ATT_display = 'jsdisplay';
+var ATT_values = 'jsvalues';
+var ATT_vars = 'jsvars';
+var ATT_eval = 'jseval';
+var ATT_transclude = 'transclude';
+var ATT_content = 'jscontent';
+var ATT_skip = 'jsskip';
+
+
+/**
+ * Name of the attribute that caches a reference to the parsed
+ * template processing attribute values on a template node.
+ */
+var ATT_jstcache = 'jstcache';
+
+
+/**
+ * Name of the property that caches the parsed template processing
+ * attribute values on a template node.
+ */
+var PROP_jstcache = '__jstcache';
+
+
+/**
+ * ID of the element that contains dynamically loaded jstemplates.
+ */
+var STRING_jsts = 'jsts';
+
+
+/**
+ * Un-inlined string literals, to avoid object creation in
+ * IE6.
+ */
+var CHAR_asterisk = '*';
+var CHAR_dollar = '$';
+var CHAR_period = '.';
+var CHAR_ampersand = '&';
+var STRING_div = 'div';
+var STRING_id = 'id';
+var STRING_asteriskzero = '*0';
+var STRING_zero = '0';
+
+
+/**
+ * HTML template processor. Data values are bound to HTML templates
+ * using the attributes transclude, jsselect, jsdisplay, jscontent,
+ * jsvalues. The template is modifed in place. The values of those
+ * attributes are JavaScript expressions that are evaluated in the
+ * context of the data object fragment.
+ *
+ * @param {JsEvalContext} context Context created from the input data
+ * object.
+ *
+ * @param {Element} template DOM node of the template. This will be
+ * processed in place. After processing, it will still be a valid
+ * template that, if processed again with the same data, will remain
+ * unchanged.
+ *
+ * @param {boolean} opt_debugging Optional flag to collect debugging
+ *     information while processing the template.  Only takes effect
+ *     in MAPS_DEBUG.
+ */
+function jstProcess(context, template, opt_debugging) {
+  var processor = new JstProcessor;
+  if (MAPS_DEBUG && opt_debugging) {
+    processor.setDebugging(opt_debugging);
+  }
+  JstProcessor.prepareTemplate_(template);
+
+  /**
+   * Caches the document of the template node, so we don't have to
+   * access it through ownerDocument.
+   * @type Document
+   */
+  processor.document_ = ownerDocument(template);
+
+  processor.run_(bindFully(processor, processor.jstProcessOuter_,
+                           context, template));
+  if (MAPS_DEBUG && opt_debugging) {
+    log('jstProcess:' + '\n' + processor.getLogs().join('\n'));
+  }
+}
+
+
+/**
+ * Internal class used by jstemplates to maintain context.  This is
+ * necessary to process deep templates in Safari which has a
+ * relatively shallow maximum recursion depth of 100.
+ * @class
+ * @constructor
+ */
+function JstProcessor() {
+  if (MAPS_DEBUG) {
+    /**
+     * An array of logging messages.  These are collected during processing
+     * and dumped to the console at the end.
+     * @type Array.<string>
+     */
+    this.logs_ = [];
+  }
+}
+
+
+/**
+ * Counter to generate node ids. These ids will be stored in
+ * ATT_jstcache and be used to lookup the preprocessed js attributes
+ * from the jstcache_. The id is stored in an attribute so it
+ * suvives cloneNode() and thus cloned template nodes can share the
+ * same cache entry.
+ * @type number
+ */
+JstProcessor.jstid_ = 0;
+
+
+/**
+ * Map from jstid to processed js attributes.
+ * @type Object
+ */
+JstProcessor.jstcache_ = {};
+
+/**
+ * The neutral cache entry. Used for all nodes that don't have any
+ * jst attributes. We still set the jsid attribute on those nodes so
+ * we can avoid to look again for all the other jst attributes that
+ * aren't there. Remember: not only the processing of the js
+ * attribute values is expensive and we thus want to cache it. The
+ * access to the attributes on the Node in the first place is
+ * expensive too.
+ */
+JstProcessor.jstcache_[0] = {};
+
+
+/**
+ * Map from concatenated attribute string to jstid.
+ * The key is the concatenation of all jst atributes found on a node
+ * formatted as "name1=value1&name2=value2&...", in the order defined by
+ * JST_ATTRIBUTES. The value is the id of the jstcache_ entry that can
+ * be used for this node. This allows the reuse of cache entries in cases
+ * when a cached entry already exists for a given combination of attribute
+ * values. (For example when two different nodes in a template share the same
+ * JST attributes.)
+ * @type Object
+ */
+JstProcessor.jstcacheattributes_ = {};
+
+
+/**
+ * Map for storing temporary attribute values in prepareNode_() so they don't
+ * have to be retrieved twice. (IE6 perf)
+ * @type Object
+ */
+JstProcessor.attributeValues_ = {};
+
+
+/**
+ * A list for storing non-empty attributes found on a node in prepareNode_().
+ * The array is global since it can be reused - this way there is no need to
+ * construct a new array object for each invocation. (IE6 perf)
+ * @type Array
+ */
+JstProcessor.attributeList_ = [];
+
+
+/**
+ * Prepares the template: preprocesses all jstemplate attributes.
+ *
+ * @param {Element} template
+ */
+JstProcessor.prepareTemplate_ = function(template) {
+  if (!template[PROP_jstcache]) {
+    domTraverseElements(template, function(node) {
+      JstProcessor.prepareNode_(node);
+    });
+  }
+};
+
+
+/**
+ * A list of attributes we use to specify jst processing instructions,
+ * and the functions used to parse their values.
+ *
+ * @type Array.<Array>
+ */
+var JST_ATTRIBUTES = [
+    [ ATT_select, jsEvalToFunction ],
+    [ ATT_display, jsEvalToFunction ],
+    [ ATT_values, jsEvalToValues ],
+    [ ATT_vars, jsEvalToValues ],
+    [ ATT_eval, jsEvalToExpressions ],
+    [ ATT_transclude, jsEvalToSelf ],
+    [ ATT_content, jsEvalToFunction ],
+    [ ATT_skip, jsEvalToFunction ]
+];
+
+
+/**
+ * Prepares a single node: preprocesses all template attributes of the
+ * node, and if there are any, assigns a jsid attribute and stores the
+ * preprocessed attributes under the jsid in the jstcache.
+ *
+ * @param {Element} node
+ *
+ * @return {Object} The jstcache entry. The processed jst attributes
+ * are properties of this object. If the node has no jst attributes,
+ * returns an object with no properties (the jscache_[0] entry).
+ */
+JstProcessor.prepareNode_ = function(node) {
+  // If the node already has a cache property, return it.
+  if (node[PROP_jstcache]) {
+    return node[PROP_jstcache];
+  }
+
+  // If it is not found, we always set the PROP_jstcache property on the node.
+  // Accessing the property is faster than executing getAttribute(). If we
+  // don't find the property on a node that was cloned in jstSelect_(), we
+  // will fall back to check for the attribute and set the property
+  // from cache.
+
+  // If the node has an attribute indexing a cache object, set it as a property
+  // and return it.
+  var jstid = domGetAttribute(node, ATT_jstcache);
+  if (jstid != null) {
+    return node[PROP_jstcache] = JstProcessor.jstcache_[jstid];
+  }
+
+  var attributeValues = JstProcessor.attributeValues_;
+  var attributeList = JstProcessor.attributeList_;
+  attributeList.length = 0;
+
+  // Look for interesting attributes.
+  for (var i = 0, I = jsLength(JST_ATTRIBUTES); i < I; ++i) {
+    var name = JST_ATTRIBUTES[i][0];
+    var value = domGetAttribute(node, name);
+    attributeValues[name] = value;
+    if (value != null) {
+      attributeList.push(name + "=" + value);
+    }
+  }
+
+  // If none found, mark this node to prevent further inspection, and return
+  // an empty cache object.
+  if (attributeList.length == 0) {
+    domSetAttribute(node, ATT_jstcache, STRING_zero);
+    return node[PROP_jstcache] = JstProcessor.jstcache_[0];
+  }
+
+  // If we already have a cache object corresponding to these attributes,
+  // annotate the node with it, and return it.
+  var attstring = attributeList.join(CHAR_ampersand);
+  if (jstid = JstProcessor.jstcacheattributes_[attstring]) {
+    domSetAttribute(node, ATT_jstcache, jstid);
+    return node[PROP_jstcache] = JstProcessor.jstcache_[jstid];
+  }
+
+  // Otherwise, build a new cache object.
+  var jstcache = {};
+  for (var i = 0, I = jsLength(JST_ATTRIBUTES); i < I; ++i) {
+    var att = JST_ATTRIBUTES[i];
+    var name = att[0];
+    var parse = att[1];
+    var value = attributeValues[name];
+    if (value != null) {
+      jstcache[name] = parse(value);
+      if (MAPS_DEBUG) {
+        jstcache.jstAttributeValues = jstcache.jstAttributeValues || {};
+        jstcache.jstAttributeValues[name] = value;
+      }
+    }
+  }
+
+  jstid = STRING_empty + ++JstProcessor.jstid_;
+  domSetAttribute(node, ATT_jstcache, jstid);
+  JstProcessor.jstcache_[jstid] = jstcache;
+  JstProcessor.jstcacheattributes_[attstring] = jstid;
+
+  return node[PROP_jstcache] = jstcache;
+};
+
+
+/**
+ * Runs the given function in our state machine.
+ *
+ * It's informative to view the set of all function calls as a tree:
+ * - nodes are states
+ * - edges are state transitions, implemented as calls to the pending
+ *   functions in the stack.
+ *   - pre-order function calls are downward edges (recursion into call).
+ *   - post-order function calls are upward edges (return from call).
+ * - leaves are nodes which do not recurse.
+ * We represent the call tree as an array of array of calls, indexed as
+ * stack[depth][index].  Here [depth] indexes into the call stack, and
+ * [index] indexes into the call queue at that depth.  We require a call
+ * queue so that a node may branch to more than one child
+ * (which will be called serially), typically due to a loop structure.
+ *
+ * @param {Function} f The first function to run.
+ */
+JstProcessor.prototype.run_ = function(f) {
+  var me = this;
+
+  /**
+   * A stack of queues of pre-order calls.
+   * The inner arrays (constituent queues) are structured as
+   * [ arg2, arg1, method, arg2, arg1, method, ...]
+   * ie. a flattened array of methods with 2 arguments, in reverse order
+   * for efficient push/pop.
+   *
+   * The outer array is a stack of such queues.
+   *
+   * @type Array.<Array>
+   */
+  var calls = me.calls_ = [];
+
+  /**
+   * The index into the queue for each depth. NOTE: Alternative would
+   * be to maintain the queues in reverse order (popping off of the
+   * end) but the repeated calls to .pop() consumed 90% of this
+   * function's execution time.
+   * @type Array.<number>
+   */
+  var queueIndices = me.queueIndices_ = [];
+
+  /**
+   * A pool of empty arrays.  Minimizes object allocation for IE6's benefit.
+   * @type Array.<Array>
+   */
+  var arrayPool = me.arrayPool_ = [];
+
+  f();
+  var queue, queueIndex;
+  var method, arg1, arg2;
+  var temp;
+  while (calls.length) {
+    queue = calls[calls.length - 1];
+    queueIndex = queueIndices[queueIndices.length - 1];
+    if (queueIndex >= queue.length) {
+      me.recycleArray_(calls.pop());
+      queueIndices.pop();
+      continue;
+    }
+
+    // Run the first function in the queue.
+    method = queue[queueIndex++];
+    arg1 = queue[queueIndex++];
+    arg2 = queue[queueIndex++];
+    queueIndices[queueIndices.length - 1] = queueIndex;
+    method.call(me, arg1, arg2);
+  }
+};
+
+
+/**
+ * Pushes one or more functions onto the stack.  These will be run in sequence,
+ * interspersed with any recursive calls that they make.
+ *
+ * This method takes ownership of the given array!
+ *
+ * @param {Array} args Array of method calls structured as
+ *     [ method, arg1, arg2, method, arg1, arg2, ... ]
+ */
+JstProcessor.prototype.push_ = function(args) {
+  this.calls_.push(args);
+  this.queueIndices_.push(0);
+};
+
+
+/**
+ * Enable/disable debugging.
+ * @param {boolean} debugging New state
+ */
+JstProcessor.prototype.setDebugging = function(debugging) {
+  if (MAPS_DEBUG) {
+    this.debugging_ = debugging;
+  }
+};
+
+
+JstProcessor.prototype.createArray_ = function() {
+  if (this.arrayPool_.length) {
+    return this.arrayPool_.pop();
+  } else {
+    return [];
+  }
+};
+
+
+JstProcessor.prototype.recycleArray_ = function(array) {
+  arrayClear(array);
+  this.arrayPool_.push(array);
+};
+
+/**
+ * Implements internals of jstProcess. This processes the two
+ * attributes transclude and jsselect, which replace or multiply
+ * elements, hence the name "outer". The remainder of the attributes
+ * is processed in jstProcessInner_(), below. That function
+ * jsProcessInner_() only processes attributes that affect an existing
+ * node, but doesn't create or destroy nodes, hence the name
+ * "inner". jstProcessInner_() is called through jstSelect_() if there
+ * is a jsselect attribute (possibly for newly created clones of the
+ * current template node), or directly from here if there is none.
+ *
+ * @param {JsEvalContext} context
+ *
+ * @param {Element} template
+ */
+JstProcessor.prototype.jstProcessOuter_ = function(context, template) {
+  var me = this;
+
+  var jstAttributes = me.jstAttributes_(template);
+  if (MAPS_DEBUG && me.debugging_) {
+    me.logState_('Outer', template, jstAttributes.jstAttributeValues);
+  }
+
+  var transclude = jstAttributes[ATT_transclude];
+  if (transclude) {
+    var tr = jstGetTemplate(transclude);
+    if (tr) {
+      domReplaceChild(tr, template);
+      var call = me.createArray_();
+      call.push(me.jstProcessOuter_, context, tr);
+      me.push_(call);
+    } else {
+      domRemoveNode(template);
+    }
+    return;
+  }
+
+  var select = jstAttributes[ATT_select];
+  if (select) {
+    me.jstSelect_(context, template, select);
+  } else {
+    me.jstProcessInner_(context, template);
+  }
+};
+
+
+/**
+ * Implements internals of jstProcess. This processes all attributes
+ * except transclude and jsselect. It is called either from
+ * jstSelect_() for nodes that have a jsselect attribute so that the
+ * jsselect attribute will not be processed again, or else directly
+ * from jstProcessOuter_(). See the comment on jstProcessOuter_() for
+ * an explanation of the name.
+ *
+ * @param {JsEvalContext} context
+ *
+ * @param {Element} template
+ */
+JstProcessor.prototype.jstProcessInner_ = function(context, template) {
+  var me = this;
+
+  var jstAttributes = me.jstAttributes_(template);
+  if (MAPS_DEBUG && me.debugging_) {
+    me.logState_('Inner', template, jstAttributes.jstAttributeValues);
+  }
+
+  // NOTE(mesch): See NOTE on ATT_content why this is a separate
+  // attribute, and not a special value in ATT_values.
+  var display = jstAttributes[ATT_display];
+  if (display) {
+    var shouldDisplay = context.jsexec(display, template);
+    if (MAPS_DEBUG && me.debugging_) {
+      me.logs_.push(ATT_display + ': ' + shouldDisplay + '<br/>');
+    }
+    if (!shouldDisplay) {
+      displayNone(template);
+      return;
+    }
+    displayDefault(template);
+  }
+
+  // NOTE(mesch): jsvars is evaluated before jsvalues, because it's
+  // more useful to be able to use var values in attribute value
+  // expressions than vice versa.
+  var values = jstAttributes[ATT_vars];
+  if (values) {
+    me.jstVars_(context, template, values);
+  }
+
+  values = jstAttributes[ATT_values];
+  if (values) {
+    me.jstValues_(context, template, values);
+  }
+
+  // Evaluate expressions immediately. Useful for hooking callbacks
+  // into jstemplates.
+  //
+  // NOTE(mesch): Evaluation order is sometimes significant, e.g. when
+  // the expression evaluated in jseval relies on the values set in
+  // jsvalues, so it needs to be evaluated *after*
+  // jsvalues. TODO(mesch): This is quite arbitrary, it would be
+  // better if this would have more necessity to it.
+  var expressions = jstAttributes[ATT_eval];
+  if (expressions) {
+    for (var i = 0, I = jsLength(expressions); i < I; ++i) {
+      context.jsexec(expressions[i], template);
+    }
+  }
+
+  var skip = jstAttributes[ATT_skip];
+  if (skip) {
+    var shouldSkip = context.jsexec(skip, template);
+    if (MAPS_DEBUG && me.debugging_) {
+      me.logs_.push(ATT_skip + ': ' + shouldSkip + '<br/>');
+    }
+    if (shouldSkip) return;
+  }
+
+  // NOTE(mesch): content is a separate attribute, instead of just a
+  // special value mentioned in values, for two reasons: (1) it is
+  // fairly common to have only mapped content, and writing
+  // content="expr" is shorter than writing values="content:expr", and
+  // (2) the presence of content actually terminates traversal, and we
+  // need to check for that. Display is a separate attribute for a
+  // reason similar to the second, in that its presence *may*
+  // terminate traversal.
+  var content = jstAttributes[ATT_content];
+  if (content) {
+    me.jstContent_(context, template, content);
+
+  } else {
+    // Newly generated children should be ignored, so we explicitly
+    // store the children to be processed.
+    var queue = me.createArray_();
+    for (var c = template.firstChild; c; c = c.nextSibling) {
+      if (c.nodeType == DOM_ELEMENT_NODE) {
+        queue.push(me.jstProcessOuter_, context, c);
+      }
+    }
+    if (queue.length) me.push_(queue);
+  }
+};
+
+
+/**
+ * Implements the jsselect attribute: evalutes the value of the
+ * jsselect attribute in the current context, with the current
+ * variable bindings (see JsEvalContext.jseval()). If the value is an
+ * array, the current template node is multiplied once for every
+ * element in the array, with the array element being the context
+ * object. If the array is empty, or the value is undefined, then the
+ * current template node is dropped. If the value is not an array,
+ * then it is just made the context object.
+ *
+ * @param {JsEvalContext} context The current evaluation context.
+ *
+ * @param {Element} template The currently processed node of the template.
+ *
+ * @param {Function} select The javascript expression to evaluate.
+ *
+ * @notypecheck FIXME(hmitchell): See OCL6434950. instance and value need
+ * type checks.
+ */
+JstProcessor.prototype.jstSelect_ = function(context, template, select) {
+  var me = this;
+
+  var value = context.jsexec(select, template);
+
+  // Enable reprocessing: if this template is reprocessed, then only
+  // fill the section instance here. Otherwise do the cardinal
+  // processing of a new template.
+  var instance = domGetAttribute(template, ATT_instance);
+
+  var instanceLast = false;
+  if (instance) {
+    if (instance.charAt(0) == CHAR_asterisk) {
+      instance = parseInt10(instance.substr(1));
+      instanceLast = true;
+    } else {
+      instance = parseInt10(/** @type string */(instance));
+    }
+  }
+
+  // The expression value instanceof Array is occasionally false for
+  // arrays, seen in Firefox. Thus we recognize an array as an object
+  // which is not null that has a length property. Notice that this
+  // also matches input data with a length property, so this property
+  // name should be avoided in input data.
+  var multiple = isArray(value);
+  var count = multiple ? jsLength(value) : 1;
+  var multipleEmpty = (multiple && count == 0);
+
+  if (multiple) {
+    if (multipleEmpty) {
+      // For an empty array, keep the first template instance and mark
+      // it last. Remove all other template instances.
+      if (!instance) {
+        domSetAttribute(template, ATT_instance, STRING_asteriskzero);
+        displayNone(template);
+      } else {
+        domRemoveNode(template);
+      }
+
+    } else {
+      displayDefault(template);
+      // For a non empty array, create as many template instances as
+      // are needed. If the template is first processed, as many
+      // template instances are needed as there are values in the
+      // array. If the template is reprocessed, new template instances
+      // are only needed if there are more array values than template
+      // instances. Those additional instances are created by
+      // replicating the last template instance.
+      //
+      // When the template is first processed, there is no jsinstance
+      // attribute. This is indicated by instance === null, except in
+      // opera it is instance === "". Notice also that the === is
+      // essential, because 0 == "", presumably via type coercion to
+      // boolean.
+      if (instance === null || instance === STRING_empty ||
+          (instanceLast && instance < count - 1)) {
+        // A queue of calls to push.
+        var queue = me.createArray_();
+
+        var instancesStart = instance || 0;
+        var i, I, clone;
+        for (i = instancesStart, I = count - 1; i < I; ++i) {
+          var node = domCloneNode(template);
+          domInsertBefore(node, template);
+
+          jstSetInstance(/** @type Element */(node), value, i);
+          clone = context.clone(value[i], i, count);
+
+          queue.push(me.jstProcessInner_, clone, node,
+                     JsEvalContext.recycle, clone, null);
+                     
+        }
+        // Push the originally present template instance last to keep
+        // the order aligned with the DOM order, because the newly
+        // created template instances are inserted *before* the
+        // original instance.
+        jstSetInstance(template, value, i);
+        clone = context.clone(value[i], i, count);
+        queue.push(me.jstProcessInner_, clone, template,
+                   JsEvalContext.recycle, clone, null);
+        me.push_(queue);
+      } else if (instance < count) {
+        var v = value[instance];
+
+        jstSetInstance(template, value, instance);
+        var clone = context.clone(v, instance, count);
+        var queue = me.createArray_();
+        queue.push(me.jstProcessInner_, clone, template,
+                   JsEvalContext.recycle, clone, null);
+        me.push_(queue);
+      } else {
+        domRemoveNode(template);
+      }
+    }
+  } else {
+    if (value == null) {
+      displayNone(template);
+    } else {
+      displayDefault(template);
+      var clone = context.clone(value, 0, 1);
+      var queue = me.createArray_();
+      queue.push(me.jstProcessInner_, clone, template,
+                 JsEvalContext.recycle, clone, null);
+      me.push_(queue);
+    }
+  }
+};
+
+
+/**
+ * Implements the jsvars attribute: evaluates each of the values and
+ * assigns them to variables in the current context. Similar to
+ * jsvalues, except that all values are treated as vars, independent
+ * of their names.
+ *
+ * @param {JsEvalContext} context Current evaluation context.
+ *
+ * @param {Element} template Currently processed template node.
+ *
+ * @param {Array} values Processed value of the jsvalues attribute: a
+ * flattened array of pairs. The second element in the pair is a
+ * function that can be passed to jsexec() for evaluation in the
+ * current jscontext, and the first element is the variable name that
+ * the value returned by jsexec is assigned to.
+ */
+JstProcessor.prototype.jstVars_ = function(context, template, values) {
+  for (var i = 0, I = jsLength(values); i < I; i += 2) {
+    var label = values[i];
+    var value = context.jsexec(values[i+1], template);
+    context.setVariable(label, value);
+  }
+};
+
+
+/**
+ * Implements the jsvalues attribute: evaluates each of the values and
+ * assigns them to variables in the current context (if the name
+ * starts with '$', javascript properties of the current template node
+ * (if the name starts with '.'), or DOM attributes of the current
+ * template node (otherwise). Since DOM attribute values are always
+ * strings, the value is coerced to string in the latter case,
+ * otherwise it's the uncoerced javascript value.
+ *
+ * @param {JsEvalContext} context Current evaluation context.
+ *
+ * @param {Element} template Currently processed template node.
+ *
+ * @param {Array} values Processed value of the jsvalues attribute: a
+ * flattened array of pairs. The second element in the pair is a
+ * function that can be passed to jsexec() for evaluation in the
+ * current jscontext, and the first element is the label that
+ * determines where the value returned by jsexec is assigned to.
+ */
+JstProcessor.prototype.jstValues_ = function(context, template, values) {
+  for (var i = 0, I = jsLength(values); i < I; i += 2) {
+    var label = values[i];
+    var value = context.jsexec(values[i+1], template);
+
+    if (label.charAt(0) == CHAR_dollar) {
+      // A jsvalues entry whose name starts with $ sets a local
+      // variable.
+      context.setVariable(label, value);
+
+    } else if (label.charAt(0) == CHAR_period) {
+      // A jsvalues entry whose name starts with . sets a property of
+      // the current template node. The name may have further dot
+      // separated components, which are translated into namespace
+      // objects. This specifically allows to set properties on .style
+      // using jsvalues. NOTE(mesch): Setting the style attribute has
+      // no effect in IE and hence should not be done anyway.
+      var nameSpaceLabel = label.substr(1).split(CHAR_period);
+      var nameSpaceObject = template;
+      var nameSpaceDepth = jsLength(nameSpaceLabel);
+      for (var j = 0, J = nameSpaceDepth - 1; j < J; ++j) {
+        var jLabel = nameSpaceLabel[j];
+        if (!nameSpaceObject[jLabel]) {
+          nameSpaceObject[jLabel] = {};
+        }
+        nameSpaceObject = nameSpaceObject[jLabel];
+      }
+      nameSpaceObject[nameSpaceLabel[nameSpaceDepth - 1]] = value;
+
+    } else if (label) {
+      // Any other jsvalues entry sets an attribute of the current
+      // template node.
+      if (typeof value == TYPE_boolean) {
+        // Handle boolean values that are set as attributes specially,
+        // according to the XML/HTML convention.
+        if (value) {
+          domSetAttribute(template, label, label);
+        } else {
+          domRemoveAttribute(template, label);
+        }
+      } else {
+        domSetAttribute(template, label, STRING_empty + value);
+      }
+    }
+  }
+};
+
+
+/**
+ * Implements the jscontent attribute. Evalutes the expression in
+ * jscontent in the current context and with the current variables,
+ * and assigns its string value to the content of the current template
+ * node.
+ *
+ * @param {JsEvalContext} context Current evaluation context.
+ *
+ * @param {Element} template Currently processed template node.
+ *
+ * @param {Function} content Processed value of the jscontent
+ * attribute.
+ */
+JstProcessor.prototype.jstContent_ = function(context, template, content) {
+  // NOTE(mesch): Profiling shows that this method costs significant
+  // time. In jstemplate_perf.html, it's about 50%. I tried to replace
+  // by HTML escaping and assignment to innerHTML, but that was even
+  // slower.
+  var value = STRING_empty + context.jsexec(content, template);
+  // Prevent flicker when refreshing a template and the value doesn't
+  // change.
+  if (template.innerHTML == value) {
+    return;
+  }
+  while (template.firstChild) {
+    domRemoveNode(template.firstChild);
+  }
+  var t = domCreateTextNode(this.document_, value);
+  domAppendChild(template, t);
+};
+
+
+/**
+ * Caches access to and parsing of template processing attributes. If
+ * domGetAttribute() is called every time a template attribute value
+ * is used, it takes more than 10% of the time.
+ *
+ * @param {Element} template A DOM element node of the template.
+ *
+ * @return {Object} A javascript object that has all js template
+ * processing attribute values of the node as properties.
+ */
+JstProcessor.prototype.jstAttributes_ = function(template) {
+  if (template[PROP_jstcache]) {
+    return template[PROP_jstcache];
+  }
+
+  var jstid = domGetAttribute(template, ATT_jstcache);
+  if (jstid) {
+    return template[PROP_jstcache] = JstProcessor.jstcache_[jstid];
+  }
+
+  return JstProcessor.prepareNode_(template);
+};
+
+
+/**
+ * Helps to implement the transclude attribute, and is the initial
+ * call to get hold of a template from its ID.
+ *
+ * If the ID is not present in the DOM, and opt_loadHtmlFn is specified, this
+ * function will call that function and add the result to the DOM, before
+ * returning the template.
+ *
+ * @param {string} name The ID of the HTML element used as template.
+ * @param {Function} opt_loadHtmlFn A function which, when called, will return
+ *   HTML that contains an element whose ID is 'name'.
+ *
+ * @return {Element|null} The DOM node of the template. (Only element nodes
+ * can be found by ID, hence it's a Element.)
+ */
+function jstGetTemplate(name, opt_loadHtmlFn) {
+  var doc = document;
+  var section;
+  if (opt_loadHtmlFn) {
+    section = jstLoadTemplateIfNotPresent(doc, name, opt_loadHtmlFn);
+  } else {
+    section = domGetElementById(doc, name);
+  }
+  if (section) {
+    JstProcessor.prepareTemplate_(section);
+    var ret = domCloneElement(section);
+    domRemoveAttribute(ret, STRING_id);
+    return ret;
+  } else {
+    return null;
+  }
+}
+
+/**
+ * This function is the same as 'jstGetTemplate' but, if the template
+ * does not exist, throw an exception.
+ *
+ * @param {string} name The ID of the HTML element used as template.
+ * @param {Function} opt_loadHtmlFn A function which, when called, will return
+ *   HTML that contains an element whose ID is 'name'.
+ *
+ * @return {Element} The DOM node of the template. (Only element nodes
+ * can be found by ID, hence it's a Element.)
+ */
+function jstGetTemplateOrDie(name, opt_loadHtmlFn) {
+  var x = jstGetTemplate(name, opt_loadHtmlFn);
+  check(x !== null);
+  return /** @type Element */(x);
+}
+
+
+/**
+ * If an element with id 'name' is not present in the document, call loadHtmlFn
+ * and insert the result into the DOM.
+ *
+ * @param {Document} doc
+ * @param {string} name
+ * @param {Function} loadHtmlFn A function that returns HTML to be inserted
+ * into the DOM.
+ * @param {string} opt_target The id of a DOM object under which to attach the
+ *   HTML once it's inserted.  An object with this id is created if it does not
+ *   exist.
+ * @return {Element} The node whose id is 'name'
+ */
+function jstLoadTemplateIfNotPresent(doc, name, loadHtmlFn, opt_target) {
+  var section = domGetElementById(doc, name);
+  if (section) {
+    return section;
+  }
+  // Load any necessary HTML and try again.
+  jstLoadTemplate_(doc, loadHtmlFn(), opt_target || STRING_jsts);
+  var section = domGetElementById(doc, name);
+  if (!section) {
+    log("Error: jstGetTemplate was provided with opt_loadHtmlFn, " +
+        "but that function did not provide the id '" + name + "'.");
+  }
+  return /** @type Element */(section);
+}
+
+
+/**
+ * Loads the given HTML text into the given document, so that
+ * jstGetTemplate can find it.
+ *
+ * We append it to the element identified by targetId, which is hidden.
+ * If it doesn't exist, it is created.
+ *
+ * @param {Document} doc The document to create the template in.
+ *
+ * @param {string} html HTML text to be inserted into the document.
+ *
+ * @param {string} targetId The id of a DOM object under which to attach the
+ *   HTML once it's inserted.  An object with this id is created if it does not
+ *   exist.
+ */
+function jstLoadTemplate_(doc, html, targetId) {
+  var existing_target = domGetElementById(doc, targetId);
+  var target;
+  if (!existing_target) {
+    target = domCreateElement(doc, STRING_div);
+    target.id = targetId;
+    displayNone(target);
+    positionAbsolute(target);
+    domAppendChild(doc.body, target);
+  } else {
+    target = existing_target;
+  }
+  var div = domCreateElement(doc, STRING_div);
+  target.appendChild(div);
+  div.innerHTML = html;
+}
+
+
+/**
+ * Sets the jsinstance attribute on a node according to its context.
+ *
+ * @param {Element} template The template DOM node to set the instance
+ * attribute on.
+ *
+ * @param {Array} values The current input context, the array of
+ * values of which the template node will render one instance.
+ *
+ * @param {number} index The index of this template node in values.
+ */
+function jstSetInstance(template, values, index) {
+  if (index == jsLength(values) - 1) {
+    domSetAttribute(template, ATT_instance, CHAR_asterisk + index);
+  } else {
+    domSetAttribute(template, ATT_instance, STRING_empty + index);
+  }
+}
+
+
+/**
+ * Log the current state.
+ * @param {string} caller An identifier for the caller of .log_.
+ * @param {Element} template The template node being processed.
+ * @param {Object} jstAttributeValues The jst attributes of the template node.
+ */
+JstProcessor.prototype.logState_ = function(
+    caller, template, jstAttributeValues) {
+  if (MAPS_DEBUG) {
+    var msg = '<table>';
+    msg += '<caption>' + caller + '</caption>';
+    msg += '<tbody>';
+    if (template.id) {
+      msg += '<tr><td>' + 'id:' + '</td><td>' + template.id + '</td></tr>';
+    }
+    if (template.name) {
+      msg += '<tr><td>' + 'name:' + '</td><td>' + template.name + '</td></tr>';
+    }
+    if (jstAttributeValues) {
+      msg += '<tr><td>' + 'attr:' +
+      '</td><td>' + jsToSource(jstAttributeValues) + '</td></tr>';
+    }
+    msg += '</tbody></table><br/>';
+    this.logs_.push(msg);
+  }
+};
+
+
+/**
+ * Retrieve the processing logs.
+ * @return {Array.<string>} The processing logs.
+ */
+JstProcessor.prototype.getLogs = function() {
+  return this.logs_;
+};
+