git ssb

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var computed = require('./computed')
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var resolve = require('./resolve')
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var forEach = require('./for-each')
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var forEachPair = require('./for-each-pair')
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var addLookupMethods = require('./lib/add-lookup-methods')
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module.exports = Merge
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function Merge (sources) {
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  var raw = {}
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  var value = {}
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  var keys = new Set()
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  var instance = computed.extended(sources, function update () {
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    var currentKeys = []
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    forEach(sources, function (source) {
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      forEachPair(source, function (key, rawValue) {
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        currentKeys.push(key)
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        keys.add(key)
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        raw[key] = rawValue
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        value[key] = resolve(rawValue)
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      })
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    })
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    // remove deleted keys
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    Array.from(keys.values()).filter(function (k) {
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      return !currentKeys.includes(k)
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    }).forEach(function (key) {
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      keys.delete(key)
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      delete raw[key]
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      delete value[key]
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    })
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    return value
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  })
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  var result = function MutantMerge (listener) {
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    return instance(listener)
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  }
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  addLookupMethods(result, raw, instance.checkUpdated)
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  return result
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}
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