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JavaScript

var defaultIsMergeableObject = require('is-mergeable-object')
function emptyTarget(val) {
return Array.isArray(val) ? [] : {}
}
function cloneUnlessOtherwiseSpecified(value, options) {
return (options.clone !== false && options.isMergeableObject(value))
? deepmerge(emptyTarget(value), value, options)
: value
}
function defaultArrayMerge(target, source, options) {
return target.concat(source).map(function(element) {
return cloneUnlessOtherwiseSpecified(element, options)
})
}
function getMergeFunction(key, options) {
if (!options.customMerge) {
return deepmerge
}
var customMerge = options.customMerge(key)
return typeof customMerge === 'function' ? customMerge : deepmerge
}
function getEnumerableOwnPropertySymbols(target) {
return Object.getOwnPropertySymbols
? Object.getOwnPropertySymbols(target).filter(function(symbol) {
return Object.propertyIsEnumerable.call(target, symbol)
})
: []
}
function getKeys(target) {
return Object.keys(target).concat(getEnumerableOwnPropertySymbols(target))
}
function propertyIsOnObject(object, property) {
try {
return property in object
} catch(_) {
return false
}
}
// Protects from prototype poisoning and unexpected merging up the prototype chain.
function propertyIsUnsafe(target, key) {
return propertyIsOnObject(target, key) // Properties are safe to merge if they don't exist in the target yet,
&& !(Object.hasOwnProperty.call(target, key) // unsafe if they exist up the prototype chain,
&& Object.propertyIsEnumerable.call(target, key)) // and also unsafe if they're nonenumerable.
}
function mergeObject(target, source, options) {
var destination = {}
if (options.isMergeableObject(target)) {
getKeys(target).forEach(function(key) {
destination[key] = cloneUnlessOtherwiseSpecified(target[key], options)
})
}
getKeys(source).forEach(function(key) {
if (propertyIsUnsafe(target, key)) {
return
}
if (propertyIsOnObject(target, key) && options.isMergeableObject(source[key])) {
destination[key] = getMergeFunction(key, options)(target[key], source[key], options)
} else {
destination[key] = cloneUnlessOtherwiseSpecified(source[key], options)
}
})
return destination
}
function deepmerge(target, source, options) {
options = options || {}
options.arrayMerge = options.arrayMerge || defaultArrayMerge
options.isMergeableObject = options.isMergeableObject || defaultIsMergeableObject
// cloneUnlessOtherwiseSpecified is added to `options` so that custom arrayMerge()
// implementations can use it. The caller may not replace it.
options.cloneUnlessOtherwiseSpecified = cloneUnlessOtherwiseSpecified
var sourceIsArray = Array.isArray(source)
var targetIsArray = Array.isArray(target)
var sourceAndTargetTypesMatch = sourceIsArray === targetIsArray
if (!sourceAndTargetTypesMatch) {
return cloneUnlessOtherwiseSpecified(source, options)
} else if (sourceIsArray) {
return options.arrayMerge(target, source, options)
} else {
return mergeObject(target, source, options)
}
}
deepmerge.all = function deepmergeAll(array, options) {
if (!Array.isArray(array)) {
throw new Error('first argument should be an array')
}
return array.reduce(function(prev, next) {
return deepmerge(prev, next, options)
}, {})
}
module.exports = deepmerge