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62 lines
1.3 KiB
62 lines
1.3 KiB
5 years ago
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const util = require('util')
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, AbstractIterator = require('abstract-leveldown').AbstractIterator
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, fastFuture = require('fast-future')
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function Iterator (db, options) {
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AbstractIterator.call(this, db)
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this.binding = db.binding.iterator(options)
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this.cache = null
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this.finished = false
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this.fastFuture = fastFuture()
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}
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util.inherits(Iterator, AbstractIterator)
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Iterator.prototype.seek = function (key) {
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if (typeof key !== 'string')
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throw new Error('seek requires a string key')
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this.cache = null
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this.binding.seek(key)
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}
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Iterator.prototype._next = function (callback) {
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var that = this
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, key
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, value
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if (this.cache && this.cache.length) {
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key = this.cache.pop()
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value = this.cache.pop()
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this.fastFuture(function () {
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callback(null, key, value)
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})
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} else if (this.finished) {
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this.fastFuture(function () {
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callback()
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})
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} else {
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this.binding.next(function (err, array, finished) {
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if (err) return callback(err)
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that.cache = array
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that.finished = finished
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that._next(callback)
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})
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}
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return this
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}
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Iterator.prototype._end = function (callback) {
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delete this.cache
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this.binding.end(callback)
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}
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module.exports = Iterator
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