angular2
Version:
Angular 2 - a web framework for modern web apps
164 lines (163 loc) • 7.92 kB
JavaScript
var __decorate = (this && this.__decorate) || function (decorators, target, key, desc) {
var c = arguments.length, r = c < 3 ? target : desc === null ? desc = Object.getOwnPropertyDescriptor(target, key) : desc, d;
if (typeof Reflect === "object" && typeof Reflect.decorate === "function") r = Reflect.decorate(decorators, target, key, desc);
else for (var i = decorators.length - 1; i >= 0; i--) if (d = decorators[i]) r = (c < 3 ? d(r) : c > 3 ? d(target, key, r) : d(target, key)) || r;
return c > 3 && r && Object.defineProperty(target, key, r), r;
};
var __metadata = (this && this.__metadata) || function (k, v) {
if (typeof Reflect === "object" && typeof Reflect.metadata === "function") return Reflect.metadata(k, v);
};
import { Directive, ChangeDetectorRef, IterableDiffers, ViewContainerRef, TemplateRef } from 'angular2/core';
import { isPresent, isBlank, getTypeNameForDebugging } from 'angular2/src/facade/lang';
import { BaseException } from "../../facade/exceptions";
/**
* The `NgFor` directive instantiates a template once per item from an iterable. The context for
* each instantiated template inherits from the outer context with the given loop variable set
* to the current item from the iterable.
*
* ### Local Variables
*
* `NgFor` provides several exported values that can be aliased to local variables:
*
* * `index` will be set to the current loop iteration for each template context.
* * `first` will be set to a boolean value indicating whether the item is the first one in the
* iteration.
* * `last` will be set to a boolean value indicating whether the item is the last one in the
* iteration.
* * `even` will be set to a boolean value indicating whether this item has an even index.
* * `odd` will be set to a boolean value indicating whether this item has an odd index.
*
* ### Change Propagation
*
* When the contents of the iterator changes, `NgFor` makes the corresponding changes to the DOM:
*
* * When an item is added, a new instance of the template is added to the DOM.
* * When an item is removed, its template instance is removed from the DOM.
* * When items are reordered, their respective templates are reordered in the DOM.
* * Otherwise, the DOM element for that item will remain the same.
*
* Angular uses object identity to track insertions and deletions within the iterator and reproduce
* those changes in the DOM. This has important implications for animations and any stateful
* controls
* (such as `<input>` elements which accept user input) that are present. Inserted rows can be
* animated in, deleted rows can be animated out, and unchanged rows retain any unsaved state such
* as user input.
*
* It is possible for the identities of elements in the iterator to change while the data does not.
* This can happen, for example, if the iterator produced from an RPC to the server, and that
* RPC is re-run. Even if the data hasn't changed, the second response will produce objects with
* different identities, and Angular will tear down the entire DOM and rebuild it (as if all old
* elements were deleted and all new elements inserted). This is an expensive operation and should
* be avoided if possible.
*
* ### Syntax
*
* - `<li *ngFor="let item of items; #i = index">...</li>`
* - `<li template="ngFor #item of items; #i = index">...</li>`
* - `<template ngFor #item [ngForOf]="items" #i="index"><li>...</li></template>`
*
* ### Example
*
* See a [live demo](http://plnkr.co/edit/KVuXxDp0qinGDyo307QW?p=preview) for a more detailed
* example.
*/
export let NgFor = class NgFor {
constructor(_viewContainer, _templateRef, _iterableDiffers, _cdr) {
this._viewContainer = _viewContainer;
this._templateRef = _templateRef;
this._iterableDiffers = _iterableDiffers;
this._cdr = _cdr;
}
set ngForOf(value) {
this._ngForOf = value;
if (isBlank(this._differ) && isPresent(value)) {
try {
this._differ = this._iterableDiffers.find(value).create(this._cdr, this._ngForTrackBy);
}
catch (e) {
throw new BaseException(`Cannot find a differ supporting object '${value}' of type '${getTypeNameForDebugging(value)}'. NgFor only supports binding to Iterables such as Arrays.`);
}
}
}
set ngForTemplate(value) {
if (isPresent(value)) {
this._templateRef = value;
}
}
set ngForTrackBy(value) { this._ngForTrackBy = value; }
ngDoCheck() {
if (isPresent(this._differ)) {
var changes = this._differ.diff(this._ngForOf);
if (isPresent(changes))
this._applyChanges(changes);
}
}
_applyChanges(changes) {
// TODO(rado): check if change detection can produce a change record that is
// easier to consume than current.
var recordViewTuples = [];
changes.forEachRemovedItem((removedRecord) => recordViewTuples.push(new RecordViewTuple(removedRecord, null)));
changes.forEachMovedItem((movedRecord) => recordViewTuples.push(new RecordViewTuple(movedRecord, null)));
var insertTuples = this._bulkRemove(recordViewTuples);
changes.forEachAddedItem((addedRecord) => insertTuples.push(new RecordViewTuple(addedRecord, null)));
this._bulkInsert(insertTuples);
for (var i = 0; i < insertTuples.length; i++) {
this._perViewChange(insertTuples[i].view, insertTuples[i].record);
}
for (var i = 0, ilen = this._viewContainer.length; i < ilen; i++) {
var viewRef = this._viewContainer.get(i);
viewRef.setLocal('first', i === 0);
viewRef.setLocal('last', i === ilen - 1);
}
changes.forEachIdentityChange((record) => {
var viewRef = this._viewContainer.get(record.currentIndex);
viewRef.setLocal('\$implicit', record.item);
});
}
_perViewChange(view, record) {
view.setLocal('\$implicit', record.item);
view.setLocal('index', record.currentIndex);
view.setLocal('even', (record.currentIndex % 2 == 0));
view.setLocal('odd', (record.currentIndex % 2 == 1));
}
_bulkRemove(tuples) {
tuples.sort((a, b) => a.record.previousIndex - b.record.previousIndex);
var movedTuples = [];
for (var i = tuples.length - 1; i >= 0; i--) {
var tuple = tuples[i];
// separate moved views from removed views.
if (isPresent(tuple.record.currentIndex)) {
tuple.view = this._viewContainer.detach(tuple.record.previousIndex);
movedTuples.push(tuple);
}
else {
this._viewContainer.remove(tuple.record.previousIndex);
}
}
return movedTuples;
}
_bulkInsert(tuples) {
tuples.sort((a, b) => a.record.currentIndex - b.record.currentIndex);
for (var i = 0; i < tuples.length; i++) {
var tuple = tuples[i];
if (isPresent(tuple.view)) {
this._viewContainer.insert(tuple.view, tuple.record.currentIndex);
}
else {
tuple.view =
this._viewContainer.createEmbeddedView(this._templateRef, tuple.record.currentIndex);
}
}
return tuples;
}
};
NgFor = __decorate([
Directive({ selector: '[ngFor][ngForOf]', inputs: ['ngForTrackBy', 'ngForOf', 'ngForTemplate'] }),
__metadata('design:paramtypes', [ViewContainerRef, TemplateRef, IterableDiffers, ChangeDetectorRef])
], NgFor);
class RecordViewTuple {
constructor(record, view) {
this.record = record;
this.view = view;
}
}