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51 lines
1.2 KiB
51 lines
1.2 KiB
4 years ago
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const util = require('util')
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const AbstractIterator = require('abstract-leveldown').AbstractIterator
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const binding = require('./binding')
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function Iterator (db, options) {
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AbstractIterator.call(this, db)
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this.context = binding.iterator_init(db.context, options)
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this.cache = null
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this.finished = false
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}
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util.inherits(Iterator, AbstractIterator)
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Iterator.prototype._seek = function (target) {
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if (target.length === 0) {
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throw new Error('cannot seek() to an empty target')
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}
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this.cache = null
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binding.iterator_seek(this.context, target)
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this.finished = false
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}
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Iterator.prototype._next = function (callback) {
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var that = this
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if (this.cache && this.cache.length) {
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process.nextTick(callback, null, this.cache.pop(), this.cache.pop())
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} else if (this.finished) {
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process.nextTick(callback)
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} else {
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binding.iterator_next(this.context, 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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binding.iterator_end(this.context, callback)
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}
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module.exports = Iterator
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