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transform.js
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transform.js
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'use strict';
const { MUTATION, WAS_WRITTEN, WAS_ACCESSED, ENTITY, ENTITIES } = require('./symbols');
const { get, set } = require('./get-set');
const concatOne = (arr, s) => {
const newArr = new Array(arr.length + 1);
for (let i = 0; i <= arr.length; i++) {
if (i < arr.length) newArr[i] = arr[i];
else newArr[i] = s;
}
return newArr;
};
const concat = concatOne;
function createStage(target, rootPatch, keys = []) {
return new Proxy(target, {
get(target, name) {
const propPatch = concat(keys, name);
let value;
const mutation = get(rootPatch, concat(propPatch, MUTATION));
if (mutation) {
return mutation.value;
}
else
value = target[name];
if (value && typeof value == 'object') {
return createStage(value, rootPatch, propPatch);
}
return value;
},
set(target, name, value) {
const oldValue = target[name];
if (value !== oldValue) {
if (Array.isArray(target)) {
let patch = get(rootPatch, keys);
if (!patch) {
patch = {};
set(rootPatch, keys, patch);
}
if (!patch[MUTATION]) {
const arrayDraft = target.slice();
// we need to explicitly assign the first changed item
// all next changes will affect arrayDraft directly
// without Proxy (`get` trap will return patch[MUTATION].value)
arrayDraft[name] = value;
patch[MUTATION] = {value: arrayDraft};
}
return true;
}
set(rootPatch, concat(keys, name), {[MUTATION]:{value}})
}
return true;
},
ownKeys(target) {
const patch = get(rootPatch, keys.concat([])) || {}
return Array.from(new Set(
Reflect.ownKeys(target).concat(Object.keys(patch))
));
},
getOwnPropertyDescriptor(target, name) {
const patch = get(rootPatch, keys) || {};
if (patch[name] && patch[name][MUTATION]) {
return {
configurable: true,
enumerable: true,
value: patch[name][MUTATION].value
}
}
return Reflect.getOwnPropertyDescriptor(target, name);
}
});
}
function applyPatch (node, patch, root, rootPatch) {
if (patch && patch[MUTATION]) {
const mutValue = patch[MUTATION].value;
if (mutValue && mutValue[ENTITY]) {
const id = mutValue[ENTITY];
if (rootPatch[ENTITIES] && rootPatch[ENTITIES] && rootPatch[ENTITIES][id]) {
return rootPatch[ENTITIES][id][MUTATION].value;
}
return root[ENTITIES][mutValue[ENTITY]];
}
return patch[MUTATION].value;
}
let symbols;
if (node && typeof node == 'object') {
symbols = Object.getOwnPropertySymbols(node);
}
if (
patch
&& node && typeof node == 'object'
//&& patch[WAS_ACCESSED]
&& Object.keys(patch).length || symbols && symbols.length
) {
let copy;
if (Array.isArray(node))
copy = node.slice();
else {
copy = {};
for (let k in node) {
copy[k] = node[k];
}
if (symbols) {
for (let i = 0; i < symbols.length; i++) {
copy[symbols[i]] = node[symbols[i]];
}
}
}
for (let k in patch) {
const res = applyPatch(node[k], patch[k], root, rootPatch);
copy[k] = res;
}
const patchSymbols = Object.getOwnPropertySymbols(patch);
for (let i = 0; i < patchSymbols.length; i++) {
const k = patchSymbols[i];
const res = applyPatch(node[k], patch[k], root, rootPatch);
copy[k] = res;
}
return copy;
}
return node;
}
exports.applyPatch = applyPatch;
const diff = require('./diff');
const copyDeep = require('./copyDeep');
const transform = (transformer, original, ...args) => {
if (typeof original == 'undefined') {
return transform.bind(null, transformer);
}
if (typeof transformer !== 'function') throw new Error(`
API was changed in 0.5.0 version of Transmutable library.
Now transform function takes transforming function as a FIRST argument.
Original state as a SECOND one.
`);
let patch;
let result;
if (typeof Proxy == 'undefined') {
const copy = copyDeep(original);
result = transformer.call(copy, copy, ...args);
patch = diff(original, copy);
} else {
patch = {};
const stage = createStage(original, patch);
result = transformer.call(stage, stage, ...args);
}
if (typeof result != 'undefined') return result;
return applyPatch(original, patch, original, patch);
}
exports.transform = transform;
// we keep Reducer separately because Reducer is meant for use with Redux
// and Transform is for general use.
// now they both share the same API and implementation
// but in future versions it may not be true
exports.Reducer = () => {
throw new Error("Transmutable: to create Redux reducer just use `transform` function with currying (look into docs)")
}
const over = (getter, setter, original) => {
if (typeof setter == 'undefined') return over.bind(null, getter);
return transform(d => {
const relativeStage = get(d, getter);
const result = setter.call(relativeStage, relativeStage);
if (typeof result != 'undefined') {
set(d, getter, result)
}
}, original);
}
exports.over = over;
exports.transformAt = over;