react-native/Libraries/vendor/core/mergeHelpers.js

161 lines
4.6 KiB
JavaScript

/**
* @generated SignedSource<<b68d78236d45828b3f7f7fcc740782a9>>
*
* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
* !! This file is a check-in of a static_upstream project! !!
* !! !!
* !! You should not modify this file directly. Instead: !!
* !! 1) Use `fjs use-upstream` to temporarily replace this with !!
* !! the latest version from upstream. !!
* !! 2) Make your changes, test them, etc. !!
* !! 3) Use `fjs push-upstream` to copy your changes back to !!
* !! static_upstream. !!
* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
*
* Copyright 2013-2014 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* @providesModule mergeHelpers
*
* requiresPolyfills: Array.isArray
*/
"use strict";
var invariant = require('invariant');
var keyMirror = require('keyMirror');
/**
* Maximum number of levels to traverse. Will catch circular structures.
* @const
*/
var MAX_MERGE_DEPTH = 36;
/**
* We won't worry about edge cases like new String('x') or new Boolean(true).
* Functions are considered terminals, and arrays are not.
* @param {*} o The item/object/value to test.
* @return {boolean} true iff the argument is a terminal.
*/
var isTerminal = function(o) {
return typeof o !== 'object' || o === null;
};
var mergeHelpers = {
MAX_MERGE_DEPTH: MAX_MERGE_DEPTH,
isTerminal: isTerminal,
/**
* Converts null/undefined values into empty object.
*
* @param {?Object=} arg Argument to be normalized (nullable optional)
* @return {!Object}
*/
normalizeMergeArg: function(arg) {
return arg === undefined || arg === null ? {} : arg;
},
/**
* If merging Arrays, a merge strategy *must* be supplied. If not, it is
* likely the caller's fault. If this function is ever called with anything
* but `one` and `two` being `Array`s, it is the fault of the merge utilities.
*
* @param {*} one Array to merge into.
* @param {*} two Array to merge from.
*/
checkMergeArrayArgs: function(one, two) {
invariant(
Array.isArray(one) && Array.isArray(two),
'Tried to merge arrays, instead got %s and %s.',
one,
two
);
},
/**
* @param {*} one Object to merge into.
* @param {*} two Object to merge from.
*/
checkMergeObjectArgs: function(one, two) {
mergeHelpers.checkMergeObjectArg(one);
mergeHelpers.checkMergeObjectArg(two);
},
/**
* @param {*} arg
*/
checkMergeObjectArg: function(arg) {
invariant(
!isTerminal(arg) && !Array.isArray(arg),
'Tried to merge an object, instead got %s.',
arg
);
},
/**
* @param {*} arg
*/
checkMergeIntoObjectArg: function(arg) {
invariant(
(!isTerminal(arg) || typeof arg === 'function') && !Array.isArray(arg),
'Tried to merge into an object, instead got %s.',
arg
);
},
/**
* Checks that a merge was not given a circular object or an object that had
* too great of depth.
*
* @param {number} Level of recursion to validate against maximum.
*/
checkMergeLevel: function(level) {
invariant(
level < MAX_MERGE_DEPTH,
'Maximum deep merge depth exceeded. You may be attempting to merge ' +
'circular structures in an unsupported way.'
);
},
/**
* Checks that the supplied merge strategy is valid.
*
* @param {string} Array merge strategy.
*/
checkArrayStrategy: function(strategy) {
invariant(
strategy === undefined || strategy in mergeHelpers.ArrayStrategies,
'You must provide an array strategy to deep merge functions to ' +
'instruct the deep merge how to resolve merging two arrays.'
);
},
/**
* Set of possible behaviors of merge algorithms when encountering two Arrays
* that must be merged together.
* - `clobber`: The left `Array` is ignored.
* - `indexByIndex`: The result is achieved by recursively deep merging at
* each index. (not yet supported.)
*/
ArrayStrategies: keyMirror({
Clobber: true,
IndexByIndex: true
})
};
module.exports = mergeHelpers;