ng2-pagination/dist/paginate.pipe.js

Pagination for Angular

"use strict";
var core_1 = require("@angular/core");
var pagination_service_1 = require("./pagination.service");
var LARGE_NUMBER = Number.MAX_SAFE_INTEGER;
var PaginatePipe = (function () {
    function PaginatePipe(service) {
        this.service = service;
        // store the values from the last time the pipe was invoked
        this.state = {};
    }
    PaginatePipe.prototype.transform = function (collection, args) {
        // When an observable is passed through the AsyncPipe, it will output
        // `null` until the subscription resolves. In this case, we want to
        // use the cached data from the `state` object to prevent the NgFor
        // from flashing empty until the real values arrive.
        if (args instanceof Array) {
            // compatible with angular2 before beta16
            args = args[0];
        }
        if (!(collection instanceof Array)) {
            var _id = args.id || this.service.defaultId;
            if (this.state[_id]) {
                return this.state[_id].slice;
            }
            else {
                return collection;
            }
        }
        var serverSideMode = args.totalItems && args.totalItems !== collection.length;
        var instance = this.createInstance(collection, args);
        var id = instance.id;
        var start, end;
        var perPage = instance.itemsPerPage;
        this.service.register(instance);
        if (!serverSideMode && collection instanceof Array) {
            perPage = +perPage || LARGE_NUMBER;
            start = (instance.currentPage - 1) * perPage;
            end = start + perPage;
            var isIdentical = this.stateIsIdentical(id, collection, start, end);
            if (isIdentical) {
                return this.state[id].slice;
            }
            else {
                var slice = collection.slice(start, end);
                this.saveState(id, collection, slice, start, end);
                this.service.change.emit(id);
                return slice;
            }
        }
        // save the state for server-side collection to avoid null
        // flash as new data loads.
        this.saveState(id, collection, collection, start, end);
        return collection;
    };
    /**
     * Create an PaginationInstance object, using defaults for any optional properties not supplied.
     */
    PaginatePipe.prototype.createInstance = function (collection, args) {
        var config = args;
        this.checkConfig(config);
        return {
            id: config.id || this.service.defaultId(),
            itemsPerPage: config.itemsPerPage || 0,
            currentPage: config.currentPage || 1,
            totalItems: config.totalItems || collection.length
        };
    };
    /**
     * Ensure the argument passed to the filter contains the required properties.
     */
    PaginatePipe.prototype.checkConfig = function (config) {
        var required = ['itemsPerPage', 'currentPage'];
        var missing = required.filter(function (prop) { return !(prop in config); });
        if (0 < missing.length) {
            throw new Error("PaginatePipe: Argument is missing the following required properties: " + missing.join(', '));
        }
    };
    /**
     * To avoid returning a brand new array each time the pipe is run, we store the state of the sliced
     * array for a given id. This means that the next time the pipe is run on this collection & id, we just
     * need to check that the collection, start and end points are all identical, and if so, return the
     * last sliced array.
     */
    PaginatePipe.prototype.saveState = function (id, collection, slice, start, end) {
        this.state[id] = {
            collection: collection,
            size: collection.length,
            slice: slice,
            start: start,
            end: end
        };
    };
    /**
     * For a given id, returns true if the collection, size, start and end values are identical.
     */
    PaginatePipe.prototype.stateIsIdentical = function (id, collection, start, end) {
        var state = this.state[id];
        if (!state) {
            return false;
        }
        var isMetaDataIdentical = state.size === collection.length &&
            state.start === start &&
            state.end === end;
        if (!isMetaDataIdentical) {
            return false;
        }
        return state.slice.every(function (element, index) { return element === collection[start + index]; });
    };
    PaginatePipe.decorators = [
        { type: core_1.Pipe, args: [{
                    name: 'paginate',
                    pure: false
                },] },
    ];
    /** @nocollapse */
    PaginatePipe.ctorParameters = function () { return [
        { type: pagination_service_1.PaginationService, },
    ]; };
    return PaginatePipe;
}());
exports.PaginatePipe = PaginatePipe;