Node JS version

node_modules/cassandra-driver/lib/datastax/graph/result-set.js

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+/*
+ * Copyright DataStax, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+'use strict';
+
+const utils = require('../../utils');
+
+/**
+ * Creates a new instance of <code>GraphResultSet</code>.
+ * @class
+ * @classdesc
+ * Represents the result set of a [graph query execution]{@link Client#executeGraph} containing vertices, edges or
+ * scalar values depending on the query.
+ * <p>
+ * It allows iteration of the items using <code>for..of</code> statements under ES2015 and exposes
+ * <code>forEach()</code>, <code>first()</code> and <code>toArray()</code> to access the underlying items.
+ * </p>
+ * @example
+ * for (let vertex of result} { ... }
+ * @example
+ * const arr = result.toArray();
+ * @example
+ * const vertex = result.first();
+ * @param {ResultSet} result
+ * @param {Function} [rowParser]
+ * @alias module:datastax/graph~GraphResultSet
+ * @constructor
+ */
+function GraphResultSet(result, rowParser) {
+  /**
+   * Information on the execution of a successful query:
+   * @member {Object}
+   * @property {Number} achievedConsistency The consistency level that has been actually achieved by the query.
+   * @property {String} queriedHost The Cassandra host that coordinated this query.
+   * @property {Object} triedHosts Gets the associative array of host that were queried before getting a valid response,
+   * being the last host the one that replied correctly.
+   * @property {Uuid} traceId Identifier of the trace session.
+   * @property {Array.<string>} warnings Warning messages generated by the server when executing the query.
+   */
+  this.info = result.info;
+  const rows = result.rows;
+  rowParser = rowParser || parsePlainJsonRow;
+
+  /**
+   * This property has been deprecated because it may return a lower value than the actual length of the results.
+   * Use <code>toArray()</code> instead.
+   * <p>Gets the length of the result.</p>
+   * @deprecated Use <code>toArray()</code> instead. This property will be removed in the following major version.
+   * @member {Number}
+   */
+  this.length = result.rowLength;
+
+  /**
+   * A string token representing the current page state of query. It can be used in the following executions to
+   * continue paging and retrieve the remained of the result for the query.
+   * @member {String}
+   */
+  this.pageState = result.pageState;
+
+  /**
+   * Returns the first element of the result or null if the result is empty.
+   * @returns {Object}
+   */
+  this.first = function first() {
+    const iterator = this.values();
+    const item = iterator.next();
+    if (item.done) {
+      return null;
+    }
+
+    return item.value;
+  };
+
+  /**
+   * Executes a provided function once per result element.
+   * @param {Function} callback Function to execute for each element, taking two arguments: currentValue and index.
+   * @param {Object} [thisArg] Value to use as <code>this</code> when executing callback.
+   */
+  this.forEach = function forEach(callback, thisArg) {
+    if (!rows.length) {
+      return;
+    }
+    const iterator = this.values();
+    let item = iterator.next();
+    let index = 0;
+    while (!item.done) {
+      callback.call(thisArg || this, item.value, index++);
+      item = iterator.next();
+    }
+  };
+
+  /**
+   * Results an Array of graph result elements (vertex, edge, scalar).
+   * @returns {Array}
+   */
+  this.toArray = function toArray() {
+    if (!rows.length) {
+      return utils.emptyArray;
+    }
+    return utils.iteratorToArray(this.values());
+  };
+
+  /**
+   * Returns a new Iterator object that contains the values for each index in the result.
+   * @returns {Iterator}
+   */
+  this.values = function* values() {
+    for (const traverser of this.getTraversers()) {
+      const bulk = traverser.bulk || 1;
+
+      for (let j = 0; j < bulk; j++) {
+        yield traverser.object;
+      }
+    }
+  };
+
+  /**
+   * Gets the traversers represented contained in the result set.
+   * @returns {Iterator}
+   */
+  this.getTraversers = function* () {
+    for (const row of rows) {
+      yield rowParser(row);
+    }
+  };
+}
+
+if (typeof Symbol !== 'undefined' && typeof Symbol.iterator === 'symbol') {
+  // Make iterable
+  GraphResultSet.prototype[Symbol.iterator] = function getIterator() {
+    return this.values();
+  };
+}
+
+/**
+ * @param {Row} row
+ * @private
+ */
+function parsePlainJsonRow(row) {
+  const parsed = JSON.parse(row['gremlin']);
+  return { object: parsed.result, bulk: parsed.bulk || 1 };
+}
+
+module.exports = GraphResultSet;