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<h1 class="page-title">Source: iterator.js</h1>
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<pre class="prettyprint source linenums"><code>/*-
*
* This file is part of Oracle NoSQL Database
* Copyright (C) 2014, 2018 Oracle and/or its affiliates. All rights reserved.
*
* If you have received this file as part of Oracle NoSQL Database the
* following applies to the work as a whole:
*
* Oracle NoSQL Database server software is free software: you can
* redistribute it and/or modify it under the terms of the GNU Affero
* General Public License as published by the Free Software Foundation,
* version 3.
*
* Oracle NoSQL Database is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Affero General Public License for more details.
*
* If you have received this file as part of Oracle NoSQL Database Client or
* distributed separately the following applies:
*
* Oracle NoSQL Database client software is free software: you can
* redistribute it and/or modify it under the terms of the Apache License
* as published by the Apache Software Foundation, version 2.0.
*
* You should have received a copy of the GNU Affero General Public License
* and/or the Apache License in the LICENSE file along with Oracle NoSQL
* Database client or server distribution. If not, see
* <http://www.gnu.org/licenses/>
* or
* <http://www.apache.org/licenses/LICENSE-2.0>.
*
* An active Oracle commercial licensing agreement for this product supersedes
* these licenses and in such case the license notices, but not the copyright
* notice, may be removed by you in connection with your distribution that is
* in accordance with the commercial licensing terms.
*
* For more information please contact:
*
* berkeleydb-info_us@oracle.com
*
*/
'use strict';
/*global Logger*/
/*global LOG_LEVELS*/
/*global Errors*/
/*global Types*/
var Parse = require('./parse');
var EventEmitter = require('events').EventEmitter;
util.inherits(Iterator, EventEmitter);
/**
* Iterator object.
* Contains a set of rows as result of parameters sent to the method
* that generated this object.
* @function {rowCallback} next Returns the next row if available.
* @function {rowCallback} getCurrent Returns the current row if available.
* @function {rowCallback} forEach Returns all the rows in sequence from
* this iterator executing the function for every row.
* @function {closeIteratorCallback} close Closes this iterator and free resources.
* @class Iterator
*/
function Iterator(/*client*/ client, /*TIteratorResult*/ iteratorResult,
/*Object*/ ResultType) {
EventEmitter.call(this);
var self = this;
var iteratorId = iteratorResult.iteratorId;
var closed = false;
var buffer =
new ResultType(iteratorResult.result).returnRows;
var hasMore = iteratorResult.hasMore;
var index, length;
var buffering = false;
resetIndexes();
function reportError(error, callback) {
callback = callback || function(){};
Logger.error(error);
callback(error);
try {
this.emit('error', error);
} catch (error) {
Logger.debug("No error event available to catch error: " + error);
}
}
function resetIndexes() {
index = 0;
length = buffer.length - 1;
}
function isClosed() {
return closed;
}
this.isClosed = isClosed;
function next(callback) {
callback = callback || function () {};
if (closed)
callback(new Errors.IteratorError('This Iterator is closed'));
if (length >= index) { //Available from buffer
var row = buffer[index++];
callback(null, row);
self.emit('data', row);
return;
}
if (hasMore) {
buffering = true;
client.iteratorNext(iteratorId, function (err, iteratorResult) {
if (err) {
var error = Errors.getProxyError(err, 'iterator.next()');
reportError(error, callback);
} else if (iteratorResult != null) {
buffer =
new ResultType(iteratorResult.result).returnRows;
hasMore = iteratorResult.hasMore;
resetIndexes();
var row = buffer[index++];
callback(null, row);
self.emit('data', row);
} else {
hasMore = false;
buffer = [];
resetIndexes();
callback(new Errors.IteratorError('No more elements on Iterator'));
self.emit('done');
}
});
} else {
callback(new Errors.IteratorError('No more elements on Iterator'));
self.emit('done');
}
}
this.next = next;
function getCurrent(callback) {
callback = callback || function () {};
Logger.debug('Iterator - getCurrent');
var _index = index - 1;
if (closed) {
callback(new Errors.IteratorError('This Iterator is closed'));
return;
}
if (length >= _index) {
callback(null, buffer[_index]);
self.emit('data', buffer[_index]);
}
}
this.getCurrent = getCurrent;
function forEach(callback) {
callback = callback || function(){};
Logger.debug('Iterator - forEach');
if (closed) {
callback(new Errors.IteratorError('This Iterator is closed'));
return;
}
var lastEntry = false;
while (true) { //Depleting buffer
if (length >= index) {
var row = buffer[index++];
callback(null, row);
self.emit('data', row);
} else if (hasMore) {
client.iteratorNext(iteratorId, function (err, iteratorResult) {
if (err) {
var error = Errors.getProxyError(err, 'iterator.next()');
reportError(error, callback);
} else if (iteratorResult != null) {
buffer =
new ResultType(iteratorResult.result).returnRows;
hasMore = iteratorResult.hasMore;
resetIndexes();
forEach(callback);
} else {
hasMore = false;
buffer = [];
lastEntry = true;
resetIndexes();
callback(new Errors.IteratorError('No more elements on Iterator'));
self.emit('done');
}
});
break;
} else {
lastEntry = true;
break;
}
}
if (lastEntry) // Means this is the last entry, no more items available
self.emit('done');
}
this.forEach = forEach;
function close(callback) {
callback = callback || function(){};
Logger.debug('Iterator - close');
if (closed) {
var error = new Errors.IteratorError('This Iterator is closed');
callback(error);
self.emit('error', error);
return;
}
client.iteratorClose(iteratorId, function closingIterator(err) {
if (err) {
var error = Errors.getProxyError(err, 'iterator.next()');
reportError(error, callback);
} else {
callback();
self.emit('close');
}
});
}
this.close = close;
}
/**
* @callback closeIteratorCallback
* @param {Error} error The error returned by the operation, if any, null
* otherwise.
*/
/**
* @callback rowCallback
* @param {Error} error The error returned by the operation, if any, null
* otherwise.
* @param {ReturnRow} result A result Object object with the row and
* metadata as result.
*/
/**
* Called when an error occurred
* @event Iterator#error
*/
/**
* Called when the Iterator is closed
* @event Iterator#close
*/
/**
* Called when the Iterator has data to be read
* @event Iterator#data
*/
/**
* Called when there is no more data available in the Iterator
* @event Iterator#done
*/
module.exports = Iterator;
</code></pre>
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