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fix(core): ensure ngFor only inserts/moves/removes elements when necessary (#10287)

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Closes #9960
Closes #7239
Closes #9672
Closes #9454
Closes #10287
This commit is contained in:
Matias Niemelä
2016-08-01 11:09:52 -07:00
committed by GitHub
parent 4df7b1cfbc
commit e18626b7a2
10 changed files with 428 additions and 91 deletions
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60
modules/@angular/core/src/change_detection/differs/default_iterable_differ.ts
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@ -63,6 +63,56 @@ export class DefaultIterableDiffer implements IterableDiffer {
}
}
forEachOperation(
fn: (item: CollectionChangeRecord, previousIndex: number, currentIndex: number) => void) {
var nextIt = this._itHead;
var nextRemove = this._removalsHead;
var addRemoveOffset = 0;
var moveOffsets: number[] = null;
while (nextIt || nextRemove) {
// Figure out which is the next record to process
// Order: remove, add, move
let record = !nextRemove ||
nextIt &&
nextIt.currentIndex < getPreviousIndex(nextRemove, addRemoveOffset, moveOffsets) ?
nextIt :
nextRemove;
var adjPreviousIndex = getPreviousIndex(record, addRemoveOffset, moveOffsets);
var currentIndex = record.currentIndex;
// consume the item, and adjust the addRemoveOffset and update moveDistance if necessary
if (record === nextRemove) {
addRemoveOffset--;
nextRemove = nextRemove._nextRemoved;
} else {
nextIt = nextIt._next;
if (record.previousIndex == null) {
addRemoveOffset++;
} else {
// INVARIANT: currentIndex < previousIndex
if (!moveOffsets) moveOffsets = [];
let localMovePreviousIndex = adjPreviousIndex - addRemoveOffset;
let localCurrentIndex = currentIndex - addRemoveOffset;
if (localMovePreviousIndex != localCurrentIndex) {
for (var i = 0; i < localMovePreviousIndex; i++) {
var offset = i < moveOffsets.length ? moveOffsets[i] : (moveOffsets[i] = 0);
var index = offset + i;
if (localCurrentIndex <= index && index < localMovePreviousIndex) {
moveOffsets[i] = offset + 1;
}
}
var previousIndex = record.previousIndex;
moveOffsets[previousIndex] = localCurrentIndex - localMovePreviousIndex;
}
}
}
if (adjPreviousIndex !== currentIndex) {
fn(record, adjPreviousIndex, currentIndex);
}
}
}
forEachPreviousItem(fn: Function) {
var record: CollectionChangeRecord;
for (record = this._previousItHead; record !== null; record = record._nextPrevious) {
@ -700,3 +750,13 @@ class _DuplicateMap {
toString(): string { return '_DuplicateMap(' + stringify(this.map) + ')'; }
}
function getPreviousIndex(item: any, addRemoveOffset: number, moveOffsets: number[]): number {
var previousIndex = item.previousIndex;
if (previousIndex === null) return previousIndex;
var moveOffset = 0;
if (moveOffsets && previousIndex < moveOffsets.length) {
moveOffset = moveOffsets[previousIndex];
}
return previousIndex + addRemoveOffset + moveOffset;
}