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1 // Copyright 2006 Google Inc. | |
2 // | |
3 // Licensed under the Apache License, Version 2.0 (the "License"); | |
4 // you may not use this file except in compliance with the License. | |
5 // You may obtain a copy of the License at | |
6 // | |
7 // http://www.apache.org/licenses/LICENSE-2.0 | |
8 // | |
9 // Unless required by applicable law or agreed to in writing, software | |
10 // distributed under the License is distributed on an "AS IS" BASIS, | |
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or | |
12 // implied. See the License for the specific language governing | |
13 // permissions and limitations under the License. | |
14 /** | |
15 * Author: Steffen Meschkat <mesch@google.com> | |
16 * | |
17 * @fileoverview A simple formatter to project JavaScript data into | |
18 * HTML templates. The template is edited in place. I.e. in order to | |
19 * instantiate a template, clone it from the DOM first, and then | |
20 * process the cloned template. This allows for updating of templates: | |
21 * If the templates is processed again, changed values are merely | |
22 * updated. | |
23 * | |
24 * NOTE(mesch): IE DOM doesn't have importNode(). | |
25 * | |
26 * NOTE(mesch): The property name "length" must not be used in input | |
27 * data, see comment in jstSelect_(). | |
28 */ | |
29 | |
30 | |
31 /** | |
32 * Names of jstemplate attributes. These attributes are attached to | |
33 * normal HTML elements and bind expression context data to the HTML | |
34 * fragment that is used as template. | |
35 */ | |
36 var ATT_select = 'jsselect'; | |
37 var ATT_instance = 'jsinstance'; | |
38 var ATT_display = 'jsdisplay'; | |
39 var ATT_values = 'jsvalues'; | |
40 var ATT_vars = 'jsvars'; | |
41 var ATT_eval = 'jseval'; | |
42 var ATT_transclude = 'transclude'; | |
43 var ATT_content = 'jscontent'; | |
44 var ATT_skip = 'jsskip'; | |
45 | |
46 | |
47 /** | |
48 * Name of the attribute that caches a reference to the parsed | |
49 * template processing attribute values on a template node. | |
50 */ | |
51 var ATT_jstcache = 'jstcache'; | |
52 | |
53 | |
54 /** | |
55 * Name of the property that caches the parsed template processing | |
56 * attribute values on a template node. | |
57 */ | |
58 var PROP_jstcache = '__jstcache'; | |
59 | |
60 | |
61 /** | |
62 * ID of the element that contains dynamically loaded jstemplates. | |
63 */ | |
64 var STRING_jsts = 'jsts'; | |
65 | |
66 | |
67 /** | |
68 * Un-inlined string literals, to avoid object creation in | |
69 * IE6. | |
70 */ | |
71 var CHAR_asterisk = '*'; | |
72 var CHAR_dollar = '$'; | |
73 var CHAR_period = '.'; | |
74 var CHAR_ampersand = '&'; | |
75 var STRING_div = 'div'; | |
76 var STRING_id = 'id'; | |
77 var STRING_asteriskzero = '*0'; | |
78 var STRING_zero = '0'; | |
79 | |
80 | |
81 /** | |
82 * HTML template processor. Data values are bound to HTML templates | |
83 * using the attributes transclude, jsselect, jsdisplay, jscontent, | |
84 * jsvalues. The template is modifed in place. The values of those | |
85 * attributes are JavaScript expressions that are evaluated in the | |
86 * context of the data object fragment. | |
87 * | |
88 * @param {JsEvalContext} context Context created from the input data | |
89 * object. | |
90 * | |
91 * @param {Element} template DOM node of the template. This will be | |
92 * processed in place. After processing, it will still be a valid | |
93 * template that, if processed again with the same data, will remain | |
94 * unchanged. | |
95 * | |
96 * @param {boolean} opt_debugging Optional flag to collect debugging | |
97 * information while processing the template. Only takes effect | |
98 * in MAPS_DEBUG. | |
99 */ | |
100 function jstProcess(context, template, opt_debugging) { | |
101 var processor = new JstProcessor; | |
102 JstProcessor.prepareTemplate_(template); | |
103 | |
104 /** | |
105 * Caches the document of the template node, so we don't have to | |
106 * access it through ownerDocument. | |
107 * @type Document | |
108 */ | |
109 processor.document_ = ownerDocument(template); | |
110 | |
111 processor.run_(bindFully(processor, processor.jstProcessOuter_, | |
112 context, template)); | |
113 } | |
114 | |
115 | |
116 /** | |
117 * Internal class used by jstemplates to maintain context. This is | |
118 * necessary to process deep templates in Safari which has a | |
119 * relatively shallow maximum recursion depth of 100. | |
120 * @class | |
121 * @constructor | |
122 */ | |
123 function JstProcessor() { | |
124 } | |
125 | |
126 | |
127 /** | |
128 * Counter to generate node ids. These ids will be stored in | |
129 * ATT_jstcache and be used to lookup the preprocessed js attributes | |
130 * from the jstcache_. The id is stored in an attribute so it | |
131 * suvives cloneNode() and thus cloned template nodes can share the | |
132 * same cache entry. | |
133 * @type number | |
134 */ | |
135 JstProcessor.jstid_ = 0; | |
136 | |
137 | |
138 /** | |
139 * Map from jstid to processed js attributes. | |
140 * @type Object | |
141 */ | |
142 JstProcessor.jstcache_ = {}; | |
143 | |
144 /** | |
145 * The neutral cache entry. Used for all nodes that don't have any | |
146 * jst attributes. We still set the jsid attribute on those nodes so | |
147 * we can avoid to look again for all the other jst attributes that | |
148 * aren't there. Remember: not only the processing of the js | |
149 * attribute values is expensive and we thus want to cache it. The | |
150 * access to the attributes on the Node in the first place is | |
151 * expensive too. | |
152 */ | |
153 JstProcessor.jstcache_[0] = {}; | |
154 | |
155 | |
156 /** | |
157 * Map from concatenated attribute string to jstid. | |
158 * The key is the concatenation of all jst atributes found on a node | |
159 * formatted as "name1=value1&name2=value2&...", in the order defined by | |
160 * JST_ATTRIBUTES. The value is the id of the jstcache_ entry that can | |
161 * be used for this node. This allows the reuse of cache entries in cases | |
162 * when a cached entry already exists for a given combination of attribute | |
163 * values. (For example when two different nodes in a template share the same | |
164 * JST attributes.) | |
165 * @type Object | |
166 */ | |
167 JstProcessor.jstcacheattributes_ = {}; | |
168 | |
169 | |
170 /** | |
171 * Map for storing temporary attribute values in prepareNode_() so they don't | |
172 * have to be retrieved twice. (IE6 perf) | |
173 * @type Object | |
174 */ | |
175 JstProcessor.attributeValues_ = {}; | |
176 | |
177 | |
178 /** | |
179 * A list for storing non-empty attributes found on a node in prepareNode_(). | |
180 * The array is global since it can be reused - this way there is no need to | |
181 * construct a new array object for each invocation. (IE6 perf) | |
182 * @type Array | |
183 */ | |
184 JstProcessor.attributeList_ = []; | |
185 | |
186 | |
187 /** | |
188 * Prepares the template: preprocesses all jstemplate attributes. | |
189 * | |
190 * @param {Element} template | |
191 */ | |
192 JstProcessor.prepareTemplate_ = function(template) { | |
193 if (!template[PROP_jstcache]) { | |
194 domTraverseElements(template, function(node) { | |
195 JstProcessor.prepareNode_(node); | |
196 }); | |
197 } | |
198 }; | |
199 | |
200 | |
201 /** | |
202 * A list of attributes we use to specify jst processing instructions, | |
203 * and the functions used to parse their values. | |
204 * | |
205 * @type Array.<Array> | |
206 */ | |
207 var JST_ATTRIBUTES = [ | |
208 [ ATT_select, jsEvalToFunction ], | |
209 [ ATT_display, jsEvalToFunction ], | |
210 [ ATT_values, jsEvalToValues ], | |
211 [ ATT_vars, jsEvalToValues ], | |
212 [ ATT_eval, jsEvalToExpressions ], | |
213 [ ATT_transclude, jsEvalToSelf ], | |
214 [ ATT_content, jsEvalToFunction ], | |
215 [ ATT_skip, jsEvalToFunction ] | |
216 ]; | |
217 | |
218 | |
219 /** | |
220 * Prepares a single node: preprocesses all template attributes of the | |
221 * node, and if there are any, assigns a jsid attribute and stores the | |
222 * preprocessed attributes under the jsid in the jstcache. | |
223 * | |
224 * @param {Element} node | |
225 * | |
226 * @return {Object} The jstcache entry. The processed jst attributes | |
227 * are properties of this object. If the node has no jst attributes, | |
228 * returns an object with no properties (the jscache_[0] entry). | |
229 */ | |
230 JstProcessor.prepareNode_ = function(node) { | |
231 // If the node already has a cache property, return it. | |
232 if (node[PROP_jstcache]) { | |
233 return node[PROP_jstcache]; | |
234 } | |
235 | |
236 // If it is not found, we always set the PROP_jstcache property on the node. | |
237 // Accessing the property is faster than executing getAttribute(). If we | |
238 // don't find the property on a node that was cloned in jstSelect_(), we | |
239 // will fall back to check for the attribute and set the property | |
240 // from cache. | |
241 | |
242 // If the node has an attribute indexing a cache object, set it as a property | |
243 // and return it. | |
244 var jstid = domGetAttribute(node, ATT_jstcache); | |
245 if (jstid != null) { | |
246 return node[PROP_jstcache] = JstProcessor.jstcache_[jstid]; | |
247 } | |
248 | |
249 var attributeValues = JstProcessor.attributeValues_; | |
250 var attributeList = JstProcessor.attributeList_; | |
251 attributeList.length = 0; | |
252 | |
253 // Look for interesting attributes. | |
254 for (var i = 0, I = jsLength(JST_ATTRIBUTES); i < I; ++i) { | |
255 var name = JST_ATTRIBUTES[i][0]; | |
256 var value = domGetAttribute(node, name); | |
257 attributeValues[name] = value; | |
258 if (value != null) { | |
259 attributeList.push(name + "=" + value); | |
260 } | |
261 } | |
262 | |
263 // If none found, mark this node to prevent further inspection, and return | |
264 // an empty cache object. | |
265 if (attributeList.length == 0) { | |
266 domSetAttribute(node, ATT_jstcache, STRING_zero); | |
267 return node[PROP_jstcache] = JstProcessor.jstcache_[0]; | |
268 } | |
269 | |
270 // If we already have a cache object corresponding to these attributes, | |
271 // annotate the node with it, and return it. | |
272 var attstring = attributeList.join(CHAR_ampersand); | |
273 if (jstid = JstProcessor.jstcacheattributes_[attstring]) { | |
274 domSetAttribute(node, ATT_jstcache, jstid); | |
275 return node[PROP_jstcache] = JstProcessor.jstcache_[jstid]; | |
276 } | |
277 | |
278 // Otherwise, build a new cache object. | |
279 var jstcache = {}; | |
280 for (var i = 0, I = jsLength(JST_ATTRIBUTES); i < I; ++i) { | |
281 var att = JST_ATTRIBUTES[i]; | |
282 var name = att[0]; | |
283 var parse = att[1]; | |
284 var value = attributeValues[name]; | |
285 if (value != null) { | |
286 jstcache[name] = parse(value); | |
287 } | |
288 } | |
289 | |
290 jstid = STRING_empty + ++JstProcessor.jstid_; | |
291 domSetAttribute(node, ATT_jstcache, jstid); | |
292 JstProcessor.jstcache_[jstid] = jstcache; | |
293 JstProcessor.jstcacheattributes_[attstring] = jstid; | |
294 | |
295 return node[PROP_jstcache] = jstcache; | |
296 }; | |
297 | |
298 | |
299 /** | |
300 * Runs the given function in our state machine. | |
301 * | |
302 * It's informative to view the set of all function calls as a tree: | |
303 * - nodes are states | |
304 * - edges are state transitions, implemented as calls to the pending | |
305 * functions in the stack. | |
306 * - pre-order function calls are downward edges (recursion into call). | |
307 * - post-order function calls are upward edges (return from call). | |
308 * - leaves are nodes which do not recurse. | |
309 * We represent the call tree as an array of array of calls, indexed as | |
310 * stack[depth][index]. Here [depth] indexes into the call stack, and | |
311 * [index] indexes into the call queue at that depth. We require a call | |
312 * queue so that a node may branch to more than one child | |
313 * (which will be called serially), typically due to a loop structure. | |
314 * | |
315 * @param {Function} f The first function to run. | |
316 */ | |
317 JstProcessor.prototype.run_ = function(f) { | |
318 var me = this; | |
319 | |
320 /** | |
321 * A stack of queues of pre-order calls. | |
322 * The inner arrays (constituent queues) are structured as | |
323 * [ arg2, arg1, method, arg2, arg1, method, ...] | |
324 * ie. a flattened array of methods with 2 arguments, in reverse order | |
325 * for efficient push/pop. | |
326 * | |
327 * The outer array is a stack of such queues. | |
328 * | |
329 * @type Array.<Array> | |
330 */ | |
331 var calls = me.calls_ = []; | |
332 | |
333 /** | |
334 * The index into the queue for each depth. NOTE: Alternative would | |
335 * be to maintain the queues in reverse order (popping off of the | |
336 * end) but the repeated calls to .pop() consumed 90% of this | |
337 * function's execution time. | |
338 * @type Array.<number> | |
339 */ | |
340 var queueIndices = me.queueIndices_ = []; | |
341 | |
342 /** | |
343 * A pool of empty arrays. Minimizes object allocation for IE6's benefit. | |
344 * @type Array.<Array> | |
345 */ | |
346 var arrayPool = me.arrayPool_ = []; | |
347 | |
348 f(); | |
349 var queue, queueIndex; | |
350 var method, arg1, arg2; | |
351 var temp; | |
352 while (calls.length) { | |
353 queue = calls[calls.length - 1]; | |
354 queueIndex = queueIndices[queueIndices.length - 1]; | |
355 if (queueIndex >= queue.length) { | |
356 me.recycleArray_(calls.pop()); | |
357 queueIndices.pop(); | |
358 continue; | |
359 } | |
360 | |
361 // Run the first function in the queue. | |
362 method = queue[queueIndex++]; | |
363 arg1 = queue[queueIndex++]; | |
364 arg2 = queue[queueIndex++]; | |
365 queueIndices[queueIndices.length - 1] = queueIndex; | |
366 method.call(me, arg1, arg2); | |
367 } | |
368 }; | |
369 | |
370 | |
371 /** | |
372 * Pushes one or more functions onto the stack. These will be run in sequence, | |
373 * interspersed with any recursive calls that they make. | |
374 * | |
375 * This method takes ownership of the given array! | |
376 * | |
377 * @param {Array} args Array of method calls structured as | |
378 * [ method, arg1, arg2, method, arg1, arg2, ... ] | |
379 */ | |
380 JstProcessor.prototype.push_ = function(args) { | |
381 this.calls_.push(args); | |
382 this.queueIndices_.push(0); | |
383 }; | |
384 | |
385 | |
386 /** | |
387 * Enable/disable debugging. | |
388 * @param {boolean} debugging New state | |
389 */ | |
390 JstProcessor.prototype.setDebugging = function(debugging) { | |
391 }; | |
392 | |
393 | |
394 JstProcessor.prototype.createArray_ = function() { | |
395 if (this.arrayPool_.length) { | |
396 return this.arrayPool_.pop(); | |
397 } else { | |
398 return []; | |
399 } | |
400 }; | |
401 | |
402 | |
403 JstProcessor.prototype.recycleArray_ = function(array) { | |
404 arrayClear(array); | |
405 this.arrayPool_.push(array); | |
406 }; | |
407 | |
408 /** | |
409 * Implements internals of jstProcess. This processes the two | |
410 * attributes transclude and jsselect, which replace or multiply | |
411 * elements, hence the name "outer". The remainder of the attributes | |
412 * is processed in jstProcessInner_(), below. That function | |
413 * jsProcessInner_() only processes attributes that affect an existing | |
414 * node, but doesn't create or destroy nodes, hence the name | |
415 * "inner". jstProcessInner_() is called through jstSelect_() if there | |
416 * is a jsselect attribute (possibly for newly created clones of the | |
417 * current template node), or directly from here if there is none. | |
418 * | |
419 * @param {JsEvalContext} context | |
420 * | |
421 * @param {Element} template | |
422 */ | |
423 JstProcessor.prototype.jstProcessOuter_ = function(context, template) { | |
424 var me = this; | |
425 | |
426 var jstAttributes = me.jstAttributes_(template); | |
427 | |
428 var transclude = jstAttributes[ATT_transclude]; | |
429 if (transclude) { | |
430 var tr = jstGetTemplate(transclude); | |
431 if (tr) { | |
432 domReplaceChild(tr, template); | |
433 var call = me.createArray_(); | |
434 call.push(me.jstProcessOuter_, context, tr); | |
435 me.push_(call); | |
436 } else { | |
437 domRemoveNode(template); | |
438 } | |
439 return; | |
440 } | |
441 | |
442 var select = jstAttributes[ATT_select]; | |
443 if (select) { | |
444 me.jstSelect_(context, template, select); | |
445 } else { | |
446 me.jstProcessInner_(context, template); | |
447 } | |
448 }; | |
449 | |
450 | |
451 /** | |
452 * Implements internals of jstProcess. This processes all attributes | |
453 * except transclude and jsselect. It is called either from | |
454 * jstSelect_() for nodes that have a jsselect attribute so that the | |
455 * jsselect attribute will not be processed again, or else directly | |
456 * from jstProcessOuter_(). See the comment on jstProcessOuter_() for | |
457 * an explanation of the name. | |
458 * | |
459 * @param {JsEvalContext} context | |
460 * | |
461 * @param {Element} template | |
462 */ | |
463 JstProcessor.prototype.jstProcessInner_ = function(context, template) { | |
464 var me = this; | |
465 | |
466 var jstAttributes = me.jstAttributes_(template); | |
467 | |
468 // NOTE(mesch): See NOTE on ATT_content why this is a separate | |
469 // attribute, and not a special value in ATT_values. | |
470 var display = jstAttributes[ATT_display]; | |
471 if (display) { | |
472 var shouldDisplay = context.jsexec(display, template); | |
473 if (!shouldDisplay) { | |
474 displayNone(template); | |
475 return; | |
476 } | |
477 displayDefault(template); | |
478 } | |
479 | |
480 // NOTE(mesch): jsvars is evaluated before jsvalues, because it's | |
481 // more useful to be able to use var values in attribute value | |
482 // expressions than vice versa. | |
483 var values = jstAttributes[ATT_vars]; | |
484 if (values) { | |
485 me.jstVars_(context, template, values); | |
486 } | |
487 | |
488 values = jstAttributes[ATT_values]; | |
489 if (values) { | |
490 me.jstValues_(context, template, values); | |
491 } | |
492 | |
493 // Evaluate expressions immediately. Useful for hooking callbacks | |
494 // into jstemplates. | |
495 // | |
496 // NOTE(mesch): Evaluation order is sometimes significant, e.g. when | |
497 // the expression evaluated in jseval relies on the values set in | |
498 // jsvalues, so it needs to be evaluated *after* | |
499 // jsvalues. TODO(mesch): This is quite arbitrary, it would be | |
500 // better if this would have more necessity to it. | |
501 var expressions = jstAttributes[ATT_eval]; | |
502 if (expressions) { | |
503 for (var i = 0, I = jsLength(expressions); i < I; ++i) { | |
504 context.jsexec(expressions[i], template); | |
505 } | |
506 } | |
507 | |
508 var skip = jstAttributes[ATT_skip]; | |
509 if (skip) { | |
510 var shouldSkip = context.jsexec(skip, template); | |
511 if (shouldSkip) return; | |
512 } | |
513 | |
514 // NOTE(mesch): content is a separate attribute, instead of just a | |
515 // special value mentioned in values, for two reasons: (1) it is | |
516 // fairly common to have only mapped content, and writing | |
517 // content="expr" is shorter than writing values="content:expr", and | |
518 // (2) the presence of content actually terminates traversal, and we | |
519 // need to check for that. Display is a separate attribute for a | |
520 // reason similar to the second, in that its presence *may* | |
521 // terminate traversal. | |
522 var content = jstAttributes[ATT_content]; | |
523 if (content) { | |
524 me.jstContent_(context, template, content); | |
525 | |
526 } else { | |
527 // Newly generated children should be ignored, so we explicitly | |
528 // store the children to be processed. | |
529 var queue = me.createArray_(); | |
530 for (var c = template.firstChild; c; c = c.nextSibling) { | |
531 if (c.nodeType == DOM_ELEMENT_NODE) { | |
532 queue.push(me.jstProcessOuter_, context, c); | |
533 } | |
534 } | |
535 if (queue.length) me.push_(queue); | |
536 } | |
537 }; | |
538 | |
539 | |
540 /** | |
541 * Implements the jsselect attribute: evalutes the value of the | |
542 * jsselect attribute in the current context, with the current | |
543 * variable bindings (see JsEvalContext.jseval()). If the value is an | |
544 * array, the current template node is multiplied once for every | |
545 * element in the array, with the array element being the context | |
546 * object. If the array is empty, or the value is undefined, then the | |
547 * current template node is dropped. If the value is not an array, | |
548 * then it is just made the context object. | |
549 * | |
550 * @param {JsEvalContext} context The current evaluation context. | |
551 * | |
552 * @param {Element} template The currently processed node of the template. | |
553 * | |
554 * @param {Function} select The javascript expression to evaluate. | |
555 * | |
556 * @notypecheck FIXME(hmitchell): See OCL6434950. instance and value need | |
557 * type checks. | |
558 */ | |
559 JstProcessor.prototype.jstSelect_ = function(context, template, select) { | |
560 var me = this; | |
561 | |
562 var value = context.jsexec(select, template); | |
563 | |
564 // Enable reprocessing: if this template is reprocessed, then only | |
565 // fill the section instance here. Otherwise do the cardinal | |
566 // processing of a new template. | |
567 var instance = domGetAttribute(template, ATT_instance); | |
568 | |
569 var instanceLast = false; | |
570 if (instance) { | |
571 if (instance.charAt(0) == CHAR_asterisk) { | |
572 instance = parseInt10(instance.substr(1)); | |
573 instanceLast = true; | |
574 } else { | |
575 instance = parseInt10(/** @type string */(instance)); | |
576 } | |
577 } | |
578 | |
579 // The expression value instanceof Array is occasionally false for | |
580 // arrays, seen in Firefox. Thus we recognize an array as an object | |
581 // which is not null that has a length property. Notice that this | |
582 // also matches input data with a length property, so this property | |
583 // name should be avoided in input data. | |
584 var multiple = isArray(value); | |
585 var count = multiple ? jsLength(value) : 1; | |
586 var multipleEmpty = (multiple && count == 0); | |
587 | |
588 if (multiple) { | |
589 if (multipleEmpty) { | |
590 // For an empty array, keep the first template instance and mark | |
591 // it last. Remove all other template instances. | |
592 if (!instance) { | |
593 domSetAttribute(template, ATT_instance, STRING_asteriskzero); | |
594 displayNone(template); | |
595 } else { | |
596 domRemoveNode(template); | |
597 } | |
598 | |
599 } else { | |
600 displayDefault(template); | |
601 // For a non empty array, create as many template instances as | |
602 // are needed. If the template is first processed, as many | |
603 // template instances are needed as there are values in the | |
604 // array. If the template is reprocessed, new template instances | |
605 // are only needed if there are more array values than template | |
606 // instances. Those additional instances are created by | |
607 // replicating the last template instance. | |
608 // | |
609 // When the template is first processed, there is no jsinstance | |
610 // attribute. This is indicated by instance === null, except in | |
611 // opera it is instance === "". Notice also that the === is | |
612 // essential, because 0 == "", presumably via type coercion to | |
613 // boolean. | |
614 if (instance === null || instance === STRING_empty || | |
615 (instanceLast && instance < count - 1)) { | |
616 // A queue of calls to push. | |
617 var queue = me.createArray_(); | |
618 | |
619 var instancesStart = instance || 0; | |
620 var i, I, clone; | |
621 for (i = instancesStart, I = count - 1; i < I; ++i) { | |
622 var node = domCloneNode(template); | |
623 domInsertBefore(node, template); | |
624 | |
625 jstSetInstance(/** @type Element */(node), value, i); | |
626 clone = context.clone(value[i], i, count); | |
627 | |
628 queue.push(me.jstProcessInner_, clone, node, | |
629 JsEvalContext.recycle, clone, null); | |
630 | |
631 } | |
632 // Push the originally present template instance last to keep | |
633 // the order aligned with the DOM order, because the newly | |
634 // created template instances are inserted *before* the | |
635 // original instance. | |
636 jstSetInstance(template, value, i); | |
637 clone = context.clone(value[i], i, count); | |
638 queue.push(me.jstProcessInner_, clone, template, | |
639 JsEvalContext.recycle, clone, null); | |
640 me.push_(queue); | |
641 } else if (instance < count) { | |
642 var v = value[instance]; | |
643 | |
644 jstSetInstance(template, value, instance); | |
645 var clone = context.clone(v, instance, count); | |
646 var queue = me.createArray_(); | |
647 queue.push(me.jstProcessInner_, clone, template, | |
648 JsEvalContext.recycle, clone, null); | |
649 me.push_(queue); | |
650 } else { | |
651 domRemoveNode(template); | |
652 } | |
653 } | |
654 } else { | |
655 if (value == null) { | |
656 displayNone(template); | |
657 } else { | |
658 displayDefault(template); | |
659 var clone = context.clone(value, 0, 1); | |
660 var queue = me.createArray_(); | |
661 queue.push(me.jstProcessInner_, clone, template, | |
662 JsEvalContext.recycle, clone, null); | |
663 me.push_(queue); | |
664 } | |
665 } | |
666 }; | |
667 | |
668 | |
669 /** | |
670 * Implements the jsvars attribute: evaluates each of the values and | |
671 * assigns them to variables in the current context. Similar to | |
672 * jsvalues, except that all values are treated as vars, independent | |
673 * of their names. | |
674 * | |
675 * @param {JsEvalContext} context Current evaluation context. | |
676 * | |
677 * @param {Element} template Currently processed template node. | |
678 * | |
679 * @param {Array} values Processed value of the jsvalues attribute: a | |
680 * flattened array of pairs. The second element in the pair is a | |
681 * function that can be passed to jsexec() for evaluation in the | |
682 * current jscontext, and the first element is the variable name that | |
683 * the value returned by jsexec is assigned to. | |
684 */ | |
685 JstProcessor.prototype.jstVars_ = function(context, template, values) { | |
686 for (var i = 0, I = jsLength(values); i < I; i += 2) { | |
687 var label = values[i]; | |
688 var value = context.jsexec(values[i+1], template); | |
689 context.setVariable(label, value); | |
690 } | |
691 }; | |
692 | |
693 | |
694 /** | |
695 * Implements the jsvalues attribute: evaluates each of the values and | |
696 * assigns them to variables in the current context (if the name | |
697 * starts with '$', javascript properties of the current template node | |
698 * (if the name starts with '.'), or DOM attributes of the current | |
699 * template node (otherwise). Since DOM attribute values are always | |
700 * strings, the value is coerced to string in the latter case, | |
701 * otherwise it's the uncoerced javascript value. | |
702 * | |
703 * @param {JsEvalContext} context Current evaluation context. | |
704 * | |
705 * @param {Element} template Currently processed template node. | |
706 * | |
707 * @param {Array} values Processed value of the jsvalues attribute: a | |
708 * flattened array of pairs. The second element in the pair is a | |
709 * function that can be passed to jsexec() for evaluation in the | |
710 * current jscontext, and the first element is the label that | |
711 * determines where the value returned by jsexec is assigned to. | |
712 */ | |
713 JstProcessor.prototype.jstValues_ = function(context, template, values) { | |
714 for (var i = 0, I = jsLength(values); i < I; i += 2) { | |
715 var label = values[i]; | |
716 var value = context.jsexec(values[i+1], template); | |
717 | |
718 if (label.charAt(0) == CHAR_dollar) { | |
719 // A jsvalues entry whose name starts with $ sets a local | |
720 // variable. | |
721 context.setVariable(label, value); | |
722 | |
723 } else if (label.charAt(0) == CHAR_period) { | |
724 // A jsvalues entry whose name starts with . sets a property of | |
725 // the current template node. The name may have further dot | |
726 // separated components, which are translated into namespace | |
727 // objects. This specifically allows to set properties on .style | |
728 // using jsvalues. NOTE(mesch): Setting the style attribute has | |
729 // no effect in IE and hence should not be done anyway. | |
730 var nameSpaceLabel = label.substr(1).split(CHAR_period); | |
731 var nameSpaceObject = template; | |
732 var nameSpaceDepth = jsLength(nameSpaceLabel); | |
733 for (var j = 0, J = nameSpaceDepth - 1; j < J; ++j) { | |
734 var jLabel = nameSpaceLabel[j]; | |
735 if (!nameSpaceObject[jLabel]) { | |
736 nameSpaceObject[jLabel] = {}; | |
737 } | |
738 nameSpaceObject = nameSpaceObject[jLabel]; | |
739 } | |
740 nameSpaceObject[nameSpaceLabel[nameSpaceDepth - 1]] = value; | |
741 | |
742 } else if (label) { | |
743 // Any other jsvalues entry sets an attribute of the current | |
744 // template node. | |
745 if (typeof value == TYPE_boolean) { | |
746 // Handle boolean values that are set as attributes specially, | |
747 // according to the XML/HTML convention. | |
748 if (value) { | |
749 domSetAttribute(template, label, label); | |
750 } else { | |
751 domRemoveAttribute(template, label); | |
752 } | |
753 } else { | |
754 domSetAttribute(template, label, STRING_empty + value); | |
755 } | |
756 } | |
757 } | |
758 }; | |
759 | |
760 | |
761 /** | |
762 * Implements the jscontent attribute. Evalutes the expression in | |
763 * jscontent in the current context and with the current variables, | |
764 * and assigns its string value to the content of the current template | |
765 * node. | |
766 * | |
767 * @param {JsEvalContext} context Current evaluation context. | |
768 * | |
769 * @param {Element} template Currently processed template node. | |
770 * | |
771 * @param {Function} content Processed value of the jscontent | |
772 * attribute. | |
773 */ | |
774 JstProcessor.prototype.jstContent_ = function(context, template, content) { | |
775 // NOTE(mesch): Profiling shows that this method costs significant | |
776 // time. In jstemplate_perf.html, it's about 50%. I tried to replace | |
777 // by HTML escaping and assignment to innerHTML, but that was even | |
778 // slower. | |
779 var value = STRING_empty + context.jsexec(content, template); | |
780 // Prevent flicker when refreshing a template and the value doesn't | |
781 // change. | |
782 if (template.innerHTML == value) { | |
783 return; | |
784 } | |
785 while (template.firstChild) { | |
786 domRemoveNode(template.firstChild); | |
787 } | |
788 var t = domCreateTextNode(this.document_, value); | |
789 domAppendChild(template, t); | |
790 }; | |
791 | |
792 | |
793 /** | |
794 * Caches access to and parsing of template processing attributes. If | |
795 * domGetAttribute() is called every time a template attribute value | |
796 * is used, it takes more than 10% of the time. | |
797 * | |
798 * @param {Element} template A DOM element node of the template. | |
799 * | |
800 * @return {Object} A javascript object that has all js template | |
801 * processing attribute values of the node as properties. | |
802 */ | |
803 JstProcessor.prototype.jstAttributes_ = function(template) { | |
804 if (template[PROP_jstcache]) { | |
805 return template[PROP_jstcache]; | |
806 } | |
807 | |
808 var jstid = domGetAttribute(template, ATT_jstcache); | |
809 if (jstid) { | |
810 return template[PROP_jstcache] = JstProcessor.jstcache_[jstid]; | |
811 } | |
812 | |
813 return JstProcessor.prepareNode_(template); | |
814 }; | |
815 | |
816 | |
817 /** | |
818 * Helps to implement the transclude attribute, and is the initial | |
819 * call to get hold of a template from its ID. | |
820 * | |
821 * If the ID is not present in the DOM, and opt_loadHtmlFn is specified, this | |
822 * function will call that function and add the result to the DOM, before | |
823 * returning the template. | |
824 * | |
825 * @param {string} name The ID of the HTML element used as template. | |
826 * @param {Function} opt_loadHtmlFn A function which, when called, will return | |
827 * HTML that contains an element whose ID is 'name'. | |
828 * | |
829 * @return {Element|null} The DOM node of the template. (Only element nodes | |
830 * can be found by ID, hence it's a Element.) | |
831 */ | |
832 function jstGetTemplate(name, opt_loadHtmlFn) { | |
833 var doc = document; | |
834 var section; | |
835 if (opt_loadHtmlFn) { | |
836 section = jstLoadTemplateIfNotPresent(doc, name, opt_loadHtmlFn); | |
837 } else { | |
838 section = domGetElementById(doc, name); | |
839 } | |
840 if (section) { | |
841 JstProcessor.prepareTemplate_(section); | |
842 var ret = domCloneElement(section); | |
843 domRemoveAttribute(ret, STRING_id); | |
844 return ret; | |
845 } else { | |
846 return null; | |
847 } | |
848 } | |
849 | |
850 /** | |
851 * This function is the same as 'jstGetTemplate' but, if the template | |
852 * does not exist, throw an exception. | |
853 * | |
854 * @param {string} name The ID of the HTML element used as template. | |
855 * @param {Function} opt_loadHtmlFn A function which, when called, will return | |
856 * HTML that contains an element whose ID is 'name'. | |
857 * | |
858 * @return {Element} The DOM node of the template. (Only element nodes | |
859 * can be found by ID, hence it's a Element.) | |
860 */ | |
861 function jstGetTemplateOrDie(name, opt_loadHtmlFn) { | |
862 var x = jstGetTemplate(name, opt_loadHtmlFn); | |
863 check(x !== null); | |
864 return /** @type Element */(x); | |
865 } | |
866 | |
867 | |
868 /** | |
869 * If an element with id 'name' is not present in the document, call loadHtmlFn | |
870 * and insert the result into the DOM. | |
871 * | |
872 * @param {Document} doc | |
873 * @param {string} name | |
874 * @param {Function} loadHtmlFn A function that returns HTML to be inserted | |
875 * into the DOM. | |
876 * @param {string} opt_target The id of a DOM object under which to attach the | |
877 * HTML once it's inserted. An object with this id is created if it does not | |
878 * exist. | |
879 * @return {Element} The node whose id is 'name' | |
880 */ | |
881 function jstLoadTemplateIfNotPresent(doc, name, loadHtmlFn, opt_target) { | |
882 var section = domGetElementById(doc, name); | |
883 if (section) { | |
884 return section; | |
885 } | |
886 // Load any necessary HTML and try again. | |
887 jstLoadTemplate_(doc, loadHtmlFn(), opt_target || STRING_jsts); | |
888 var section = domGetElementById(doc, name); | |
889 if (!section) { | |
890 log("Error: jstGetTemplate was provided with opt_loadHtmlFn, " + | |
891 "but that function did not provide the id '" + name + "'."); | |
892 } | |
893 return /** @type Element */(section); | |
894 } | |
895 | |
896 | |
897 /** | |
898 * Loads the given HTML text into the given document, so that | |
899 * jstGetTemplate can find it. | |
900 * | |
901 * We append it to the element identified by targetId, which is hidden. | |
902 * If it doesn't exist, it is created. | |
903 * | |
904 * @param {Document} doc The document to create the template in. | |
905 * | |
906 * @param {string} html HTML text to be inserted into the document. | |
907 * | |
908 * @param {string} targetId The id of a DOM object under which to attach the | |
909 * HTML once it's inserted. An object with this id is created if it does not | |
910 * exist. | |
911 */ | |
912 function jstLoadTemplate_(doc, html, targetId) { | |
913 var existing_target = domGetElementById(doc, targetId); | |
914 var target; | |
915 if (!existing_target) { | |
916 target = domCreateElement(doc, STRING_div); | |
917 target.id = targetId; | |
918 displayNone(target); | |
919 positionAbsolute(target); | |
920 domAppendChild(doc.body, target); | |
921 } else { | |
922 target = existing_target; | |
923 } | |
924 var div = domCreateElement(doc, STRING_div); | |
925 target.appendChild(div); | |
926 div.innerHTML = html; | |
927 } | |
928 | |
929 | |
930 /** | |
931 * Sets the jsinstance attribute on a node according to its context. | |
932 * | |
933 * @param {Element} template The template DOM node to set the instance | |
934 * attribute on. | |
935 * | |
936 * @param {Array} values The current input context, the array of | |
937 * values of which the template node will render one instance. | |
938 * | |
939 * @param {number} index The index of this template node in values. | |
940 */ | |
941 function jstSetInstance(template, values, index) { | |
942 if (index == jsLength(values) - 1) { | |
943 domSetAttribute(template, ATT_instance, CHAR_asterisk + index); | |
944 } else { | |
945 domSetAttribute(template, ATT_instance, STRING_empty + index); | |
946 } | |
947 } | |
948 | |
949 | |
950 /** | |
951 * Log the current state. | |
952 * @param {string} caller An identifier for the caller of .log_. | |
953 * @param {Element} template The template node being processed. | |
954 * @param {Object} jstAttributeValues The jst attributes of the template node. | |
955 */ | |
956 JstProcessor.prototype.logState_ = function( | |
957 caller, template, jstAttributeValues) { | |
958 }; | |
959 | |
960 | |
961 /** | |
962 * Retrieve the processing logs. | |
963 * @return {Array.<string>} The processing logs. | |
964 */ | |
965 JstProcessor.prototype.getLogs = function() { | |
966 return this.logs_; | |
967 }; | |
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