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virtual-array.ts
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161 lines (128 loc) · 4.32 KB
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import observable = require("data/observable");
import types = require("utils/types");
import virtualArrayDef = require("data/virtual-array");
var CHANGE = "change", UPDATE = "update", DELETE = "delete", ADD = "add";
export module knownEvents {
export var itemsLoading = "itemsLoading";
export var change = "change";
}
export class ChangeType implements virtualArrayDef.ChangeType {
static Add = "add";
static Delete = "delete";
static Update = "update";
static Splice = "splice";
}
export class VirtualArray<T> extends observable.Observable {
private _requestedIndexes: Array<number>;
private _loadedIndexes: Array<number>;
private _length: number;
private _cache: {};
constructor(length = 0) {
super();
this._length = length;
this._cache = {};
this._requestedIndexes = [];
this._loadedIndexes = [];
}
get length(): number {
return this._length;
}
set length(value: number) {
if (this._length !== value) {
var index = this._length;
var count = value - this._length;
this._length = value;
this.notify({
eventName: CHANGE, object: this,
action: count > 0 ? ADD : DELETE,
index: index,
removed: new Array(count < 0 ? Math.abs(count) : 0),
addedCount: count > 0 ? count : 0
});
}
}
private _loadSize: number;
get loadSize(): number {
return this._loadSize;
}
set loadSize(value: number) {
this._loadSize = value;
}
getItem(index: number): T {
var item = this._cache[index];
if (types.isUndefined(item)) {
if (index >= 0 && index < this.length && this._requestedIndexes.indexOf(index) < 0 && this._loadedIndexes.indexOf(index) < 0) {
this.requestItems(index);
}
}
return item;
}
setItem(index: number, value: T) {
if (this._cache[index] !== value) {
this.load(index, [value]);
}
}
load(index: number, items: T[]): void {
var i: number;
for (i = 0; i < items.length; i++) {
var itemIndex = index + i;
this._cache[itemIndex] = items[i];
this._requestedIndexes.splice(this._requestedIndexes.indexOf(itemIndex), 1);
if (this._loadedIndexes.indexOf(itemIndex) < 0) {
this._loadedIndexes.push(itemIndex);
}
}
// Remove requested but never loaded indexes.
if (this._requestedIndexes.length > 0) {
for (i = 0; i < this.loadSize - items.length; i++) {
this._requestedIndexes.splice(this._requestedIndexes.indexOf(index + i), 1);
}
}
this.notify({
eventName: CHANGE, object: this,
action: UPDATE,
index: index,
removed: new Array(items.length),
addedCount: items.length
});
}
private requestItems(index: number): void {
var indexesToLoad = [];
var pageIndex = this._loadSize > 0 ? this._loadSize * Math.floor(index / this._loadSize) : index;
var count = 0;
var start = -1;
for (var i = 0; i < this.loadSize; i++) {
var itemIndex = pageIndex + i;
if (itemIndex >= this._length) {
break;
}
if (this._loadedIndexes.indexOf(itemIndex) < 0) {
if (start < 0) {
start = itemIndex;
}
indexesToLoad.push(itemIndex);
if (this._requestedIndexes.indexOf(itemIndex) < 0) {
this._requestedIndexes.push(itemIndex);
}
count++;
} else {
if (count > 0) {
this.notify({
eventName: knownEvents.itemsLoading, object: this,
index: start,
count: count
});
}
start = -1;
count = 0;
}
}
if (start >= 0 && count > 0) {
this.notify({
eventName: knownEvents.itemsLoading, object: this,
index: start,
count: count
});
}
}
}