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[addons] update() immutability helper
Dealing with immutable data is hard. This provides a simple helper (ported from the IG codebase) that makes dealing with immutable JSON data easier. Designed to be familiar for people who use MongoDB.
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‎src/addons/__tests__/update-test.js‎

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/**
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* Copyright 2013-2014 Facebook, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* @emails react-core
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*/
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"use strict";
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var update = require('update');
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describe('update', function() {
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it('should support push', function() {
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expect(update([1], {$push: [7]})).toEqual([1, 7]);
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expect(update.bind(null, [], {$push: 7})).toThrow(
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'Invariant Violation: update(): expected spec of $push to be an ' +
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'array; got 7. Did you forget to wrap your parameter in an array?'
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);
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expect(update.bind(null, 1, {$push: 7})).toThrow(
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'Invariant Violation: update(): expected target of $push to be an ' +
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'array; got 1.'
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);
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});
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it('should support unshift', function() {
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expect(update([1], {$unshift: [7]})).toEqual([7, 1]);
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expect(update.bind(null, [], {$unshift: 7})).toThrow(
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'Invariant Violation: update(): expected spec of $unshift to be an ' +
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'array; got 7. Did you forget to wrap your parameter in an array?'
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);
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expect(update.bind(null, 1, {$unshift: 7})).toThrow(
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'Invariant Violation: update(): expected target of $unshift to be an ' +
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'array; got 1.'
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);
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});
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it('should support splice', function() {
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expect(update([1, 4, 3], {$splice: [[1, 1, 2]]})).toEqual([1, 2, 3]);
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expect(update.bind(null, [], {$splice: 1})).toThrow(
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'Invariant Violation: update(): expected spec of $splice to be an ' +
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'array of arrays; got 1. Did you forget to wrap your parameters in an '+
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'array?'
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);
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expect(update.bind(null, [], {$splice: [1]})).toThrow(
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'Invariant Violation: update(): expected spec of $splice to be an ' +
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'array of arrays; got 1. Did you forget to wrap your parameters in an ' +
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'array?'
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);
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expect(update.bind(null, 1, {$splice: 7})).toThrow(
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'Invariant Violation: Expected $splice target to be an array; got 1'
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);
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});
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it('should support merge', function() {
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expect(update({a: 'b'}, {$merge: {c: 'd'}})).toEqual({a: 'b', c: 'd'});
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expect(update.bind(null, {}, {$merge: 7})).toThrow(
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'Invariant Violation: update(): $merge expects a spec of type ' +
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'\'object\'; got 7'
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);
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expect(update.bind(null, 7, {$merge: {a: 'b'}})).toThrow(
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'Invariant Violation: update(): $merge expects a target of type ' +
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'\'object\'; got 7'
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);
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});
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it('should support set', function() {
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expect(update({a: 'b'}, {$set: {c: 'd'}})).toEqual({c: 'd'});
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});
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it('should support deep updates', function() {
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expect(update({a: 'b', c: {d: 'e'}}, {c: {d: {$set: 'f'}}})).toEqual({
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a: 'b',
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c: {d: 'f'}
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});
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});
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it('should require a directive', function() {
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expect(update.bind(null, {a: 'b'}, {a: 'c'})).toThrow(
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'Invariant Violation: update(): You provided a key path to update() ' +
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'that did not contain one of $push, $unshift, $splice, $set, $merge. ' +
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'Did you forget to include {$set: ...}?'
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);
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});
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});

‎src/addons/update.js‎

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/**
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* Copyright 2013-2014 Facebook, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* @providesModule update
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*/
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"use strict";
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var copyProperties = require('copyProperties');
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var keyOf = require('keyOf');
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var invariant = require('invariant');
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function shallowCopy(x) {
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if (Array.isArray(x)) {
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return x.concat();
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} else if (x && typeof x === 'object') {
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return copyProperties(new x.constructor(), x);
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} else {
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return x;
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}
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}
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var DIRECTIVE_PUSH = keyOf({$push: null});
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var DIRECTIVE_UNSHIFT = keyOf({$unshift: null});
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var DIRECTIVE_SPLICE = keyOf({$splice: null});
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var DIRECTIVE_SET = keyOf({$set: null});
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var DIRECTIVE_MERGE = keyOf({$merge: null});
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var ALL_DIRECTIVES_LIST = [
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DIRECTIVE_PUSH,
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DIRECTIVE_UNSHIFT,
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DIRECTIVE_SPLICE,
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DIRECTIVE_SET,
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DIRECTIVE_MERGE
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];
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var ALL_DIRECTIVES_SET = {};
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ALL_DIRECTIVES_LIST.forEach(function(directive) {
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ALL_DIRECTIVES_SET[directive] = true;
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});
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function invariantArrayCase(value, spec, directive) {
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invariant(
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Array.isArray(value),
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'update(): expected target of %s to be an array; got %s.',
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directive,
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value
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);
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var specValue = spec[directive];
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invariant(
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Array.isArray(specValue),
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'update(): expected spec of %s to be an array; got %s. ' +
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'Did you forget to wrap your parameter in an array?',
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directive,
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specValue
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);
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}
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function update(value, spec) {
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invariant(
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typeof spec === 'object',
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'update(): You provided a key path to update() that did not contain one ' +
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'of %s. Did you forget to include {%s: ...}?',
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ALL_DIRECTIVES_LIST.join(', '),
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DIRECTIVE_SET
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);
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if (spec.hasOwnProperty(DIRECTIVE_SET)) {
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invariant(
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Object.keys(spec).length === 1,
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'Cannot have more than one key in an object with %s',
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DIRECTIVE_SET
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);
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return spec[DIRECTIVE_SET];
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}
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var nextValue = shallowCopy(value);
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if (spec.hasOwnProperty(DIRECTIVE_MERGE)) {
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var mergeObj = spec[DIRECTIVE_MERGE];
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invariant(
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mergeObj && typeof mergeObj === 'object',
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'update(): %s expects a spec of type \'object\'; got %s',
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DIRECTIVE_MERGE,
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mergeObj
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);
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invariant(
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nextValue && typeof nextValue === 'object',
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'update(): %s expects a target of type \'object\'; got %s',
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DIRECTIVE_MERGE,
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nextValue
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);
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copyProperties(nextValue, spec[DIRECTIVE_MERGE]);
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}
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if (spec.hasOwnProperty(DIRECTIVE_PUSH)) {
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invariantArrayCase(value, spec, DIRECTIVE_PUSH);
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spec[DIRECTIVE_PUSH].forEach(function(item) {
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nextValue.push(item);
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});
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}
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if (spec.hasOwnProperty(DIRECTIVE_UNSHIFT)) {
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invariantArrayCase(value, spec, DIRECTIVE_UNSHIFT);
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spec[DIRECTIVE_UNSHIFT].forEach(function(item) {
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nextValue.unshift(item);
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});
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}
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if (spec.hasOwnProperty(DIRECTIVE_SPLICE)) {
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invariant(
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Array.isArray(value),
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'Expected %s target to be an array; got %s',
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DIRECTIVE_SPLICE,
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value
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);
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invariant(
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Array.isArray(spec[DIRECTIVE_SPLICE]),
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'update(): expected spec of %s to be an array of arrays; got %s. ' +
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'Did you forget to wrap your parameters in an array?',
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DIRECTIVE_SPLICE,
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spec[DIRECTIVE_SPLICE]
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);
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spec[DIRECTIVE_SPLICE].forEach(function(args) {
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invariant(
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Array.isArray(args),
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'update(): expected spec of %s to be an array of arrays; got %s. ' +
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'Did you forget to wrap your parameters in an array?',
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DIRECTIVE_SPLICE,
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spec[DIRECTIVE_SPLICE]
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);
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nextValue.splice.apply(nextValue, args);
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});
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}
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for (var k in spec) {
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if (!ALL_DIRECTIVES_SET[k]) {
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nextValue[k] = update(value[k], spec[k]);
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}
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}
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return nextValue;
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}
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module.exports = update;

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