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syncArrays.js
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syncArrays.js
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// The MIT License (MIT)
//
// Copyright (c) 2015-2021 Camptocamp SA
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
/**
* Provides a function that synchronizes two arrays, arr1 and
* arr2. arr2 is a subset of arr1, it includes the elements of arr1 that passes
* the filter. When elements are added to/removed from arr1, arr2 is updated to
* include the elements of arr1 that pass the filter. When the order of
* elements in arr2 changes, arr1 is reordered to have the same order as arr2.
*
* This can for example be used to synchronize the array of layers in the map
* with the array of selected layers, where layers may be added to/removed from
* the map, and the order of selected layers may change.
*
* let dereg = ngeoSyncArrays(map.getLayers().getArray(), selectedLayers,
* true, scope, function(layer) {
* // exclude the layer at index 0 in the map
* return map.getLayers().indexOf(layer) !== 0;
* });
*
* This will return a function that can be called to cancel synchronization.
*
* @param {T[]} arr1 Array 1.
* @param {T[]} arr2 Array 2.
* @param {boolean} reverse `true` if arr2 is in reverse order, `false`
* otherwise.
* @param {angular.IScope} scope Angular scope. Used to watch arr1 and arr2
* using $watchCollection.
* @param {function(T):boolean} filter Filter function.
* @returns {function()} Function to call to stop synchronization
* @template T
* @hidden
*/
function syncArrays(arr1, arr2, reverse, scope, filter) {
// Update arr2 when elements are added to, or removed from, arr1.
const dereg1 = scope.$watchCollection(
() => arr1,
() => {
let i, ii, j;
if (reverse) {
for (i = arr1.length - 1, j = 0; i >= 0; --i) {
if (filter(arr1[i])) {
arr2[j++] = arr1[i];
}
}
} else {
for (i = 0, ii = arr1.length, j = 0; i < ii; ++i) {
if (filter(arr1[i])) {
arr2[j++] = arr1[i];
}
}
}
arr2.length = j;
}
);
// Update arr1 when the order of elements changes in arr2.
const dereg2 = scope.$watchCollection(
() => arr2,
() => {
let i, ii, j;
if (reverse) {
for (i = 0, ii = arr1.length, j = arr2.length - 1; i < ii; ++i) {
if (filter(arr1[i])) {
arr1[i] = arr2[j--];
}
}
console.assert(j == -1);
} else {
for (i = 0, ii = arr1.length, j = 0; i < ii; ++i) {
if (filter(arr1[i])) {
arr1[i] = arr2[j++];
}
}
console.assert(j == arr2.length);
}
}
);
return function () {
dereg1();
dereg2();
};
}
export default syncArrays;