immutability-util
Version:
Mutate a copy of data without changing the original source. Inspired by immutability-helper.
331 lines (295 loc) • 7.7 kB
JavaScript
/**
* Copyright (c) 2017 hustcc
* License: MIT
* GitHub: https://github.com/hustcc/immutability-util
*
* Inspired by:
*
* https://github.com/kolodny/immutability-helper
* https://github.com/ProtoTeam/immutability-helper-x
*
* [Notice]
* Version 0.0.x -> 0.1.x
* Copy the data when using the methods, and the `value()` API only return the current state which is immutable.
* When call multiple methods, will has repeated data copy.
*
* Version 0.2.x (TODO)
* Only save the path array and value, and copy the data when calling `value()` API.
* Only do data copy once on the node, will get much more performance.
*
**/
const invariant = require('./invariant.js');
class ImmutabilityUtil {
/**
* @param state
*/
constructor(state = {}) {
this.state = state; // state data
this.commands = this._commands();
}
_commands = () => ({
$apply: (value, origin) => {
this._invariantApply(value);
return value(origin);
},
$merge: (value, origin) => {
this._invariantMerge(value, origin);
let next = origin;
this._allKeys(value).forEach((key) => {
if (value[key] !== next[key]) {
if (next === origin) next = this._copy(origin);
next[key] = value[key];
}
});
return next;
},
$push: (value, origin) => {
this._invariantPushAndUnshift(value, origin, '$push');
return value.length ? origin.concat(value) : origin;
},
$set: value => value,
$splice: (value, origin) => {
this._invariantSplices(value, origin);
let next = origin;
value.forEach((splice) => {
this._invariantSplice(splice);
if (next === origin && splice.length) next = this._copy(origin);
Array.prototype.splice.apply(next, splice);
});
return next;
},
$unset: (value, origin) => {
this._invariantUnset(value);
let next = origin;
value.forEach((key) => {
if (Object.hasOwnProperty.call(next, key)) {
if (next === origin) next = this._copy(origin);
delete next[key];
}
});
return next;
},
$unshift: (value, origin) => {
this._invariantPushAndUnshift(value, origin, '$unshift');
return value.length ? value.concat(origin) : origin;
},
});
/**
* Clone object.
* @param object
* @returns {*}
* @private
*/
_copy = (object) => {
if (object instanceof Array) return object.slice();
else if (object && typeof object === 'object') return Object.assign(new object.constructor(), object);
return object;
};
/**
* Get all keys of object. Symbols supported.
* @param obj
* @returns {*}
* @private
*/
_allKeys = (obj) => {
if (typeof Object.getOwnPropertySymbols === 'function') {
return Object.keys(obj).concat(Object.getOwnPropertySymbols(obj));
}
return Object.keys(obj);
};
/**
* Get path array from path string.
* path string is the string like `app.ui.data`, split by .
* @param path
* @returns {Array|*}
* @private
*/
_pathArray = (path) => {
if (Array.isArray(path)) return path.filter(e => !!e);
// [n] => .n
path = path.replace(/(\[\d+\])/g, s => `.${s.slice(1, -1)}`);
return path.split('.').filter(e => !!e);
};
/**
* 核心处理函数
* @param path
* @param update
* @param processor 处理的函数
* @private
*/
_process = (path, update, processor) => {
path = this._pathArray(path);
const length = path.length;
// start to loop the path string.
const _loop = (state, i) => {
let nextState = state;
if (i < length - 1) {
i += 1;
const key = path[i];
const nextStateForKey = _loop(nextState[key], i);
if (nextStateForKey !== nextState[key]) {
if (nextState === state) {
// console.log('copy', key);
nextState = this._copy(state);
}
nextState[key] = nextStateForKey;
}
} else {
nextState = processor(update, state);
}
return nextState;
};
this.state = _loop(this.state, -1);
};
/**
* $apply
* @param path
* @param value
* @returns {ImmutabilityUtil}
*/
$apply = (path, value) => {
this._process(path, value, this.commands.$apply);
return this;
};
/**
* $merge
* @param path
* @param value
* @returns {ImmutabilityUtil}
*/
$merge = (path, value) => {
this._process(path, value, this.commands.$merge);
return this;
};
/**
* $push
* @param path
* @param value
* @returns {ImmutabilityUtil}
*/
$push = (path, value) => {
this._process(path, value, this.commands.$push);
return this;
};
/**
* $set
* @param path
* @param value
* @returns {ImmutabilityUtil}
*/
$set =(path, value) => {
this._process(path, value, this.commands.$set);
return this;
};
/**
* $splice
* @param path
* @param value
* @returns {ImmutabilityUtil}
*/
$splice = (path, value) => {
this._process(path, value, this.commands.$splice);
return this;
};
/**
* $unset
* @param path
* @param value
* @returns {ImmutabilityUtil}
*/
$unset = (path, value) => {
this._process(path, value, this.commands.$unset);
return this;
};
/**
* $unshift
* @param path
* @param value
* @returns {ImmutabilityUtil}
*/
$unshift = (path, value) => {
this._process(path, value, this.commands.$unshift);
return this;
};
/**
* get the state value.
* @returns {{}|*}
*/
value = () => this.state;
setState = (state) => {
this.state = state;
return this;
};
// invariants
_invariantPushAndUnshift = (value, origin, command) => {
invariant(
Array.isArray(origin),
'iu(): expected target of %s to be an array; got %s.',
command,
origin
);
invariant(
Array.isArray(value),
'iu(): expected value of %s to be an array; got %s. Did you forget to wrap your parameters in an array?',
command,
value
);
};
_invariantSplices = (value, origin) => {
invariant(
Array.isArray(origin),
'iu(): expected target of $splice to be an array; got %s.',
origin
);
this._invariantSplice(value);
};
_invariantSplice = (value) => {
invariant(
Array.isArray(value),
'iu(): expected value of $splice to be an array of arrays; got %s. ' +
'Did you forget to wrap your parameters in an array?',
value
);
};
_invariantApply = (fn) => {
invariant(
typeof fn === 'function',
'iu(): expected target of $apply to be a function; got %s.',
fn
);
};
_invariantMerge = (value, origin) => {
invariant(
value && typeof value === 'object',
'iu(): expected value of $merge to be an \'object\'; got %s.',
value
);
invariant(
origin && typeof origin === 'object',
'iu(): expected target of $merge to be an \'object\'; got %s.',
origin
);
};
_invariantUnset = (value) => {
invariant(
Array.isArray(value),
'iu(): expected value of $unset to be an array; got %s. Did you forget to wrap your parameters in an array?',
value
);
};
}
// 单例模式，提高性能
const instance = new ImmutabilityUtil();
/**
* 库函数入口
* @param state 需要被修改的 state 状态
* @param newInstance 默认使用单例，提高性能
* @returns {ImmutabilityUtil}
*/
const entry = (state, newInstance = false) => {
if (newInstance) {
return new ImmutabilityUtil(state);
}
return instance.setState(state);
};
module.exports = entry;