Initial commit

node_modules/mongodb/lib/core/utils.js

@@ -0,0 +1,297 @@
+'use strict';
+const os = require('os');
+const crypto = require('crypto');
+const requireOptional = require('require_optional');
+
+/**
+ * Generate a UUIDv4
+ */
+const uuidV4 = () => {
+  const result = crypto.randomBytes(16);
+  result[6] = (result[6] & 0x0f) | 0x40;
+  result[8] = (result[8] & 0x3f) | 0x80;
+  return result;
+};
+
+/**
+ * Relays events for a given listener and emitter
+ *
+ * @param {EventEmitter} listener the EventEmitter to listen to the events from
+ * @param {EventEmitter} emitter the EventEmitter to relay the events to
+ */
+function relayEvents(listener, emitter, events) {
+  events.forEach(eventName => listener.on(eventName, event => emitter.emit(eventName, event)));
+}
+
+function retrieveKerberos() {
+  let kerberos;
+
+  try {
+    kerberos = requireOptional('kerberos');
+  } catch (err) {
+    if (err.code === 'MODULE_NOT_FOUND') {
+      throw new Error('The `kerberos` module was not found. Please install it and try again.');
+    }
+
+    throw err;
+  }
+
+  return kerberos;
+}
+
+// Throw an error if an attempt to use EJSON is made when it is not installed
+const noEJSONError = function() {
+  throw new Error('The `mongodb-extjson` module was not found. Please install it and try again.');
+};
+
+// Facilitate loading EJSON optionally
+function retrieveEJSON() {
+  let EJSON = null;
+  try {
+    EJSON = requireOptional('mongodb-extjson');
+  } catch (error) {} // eslint-disable-line
+  if (!EJSON) {
+    EJSON = {
+      parse: noEJSONError,
+      deserialize: noEJSONError,
+      serialize: noEJSONError,
+      stringify: noEJSONError,
+      setBSONModule: noEJSONError,
+      BSON: noEJSONError
+    };
+  }
+
+  return EJSON;
+}
+
+/**
+ * A helper function for determining `maxWireVersion` between legacy and new topology
+ * instances
+ *
+ * @private
+ * @param {(Topology|Server)} topologyOrServer
+ */
+function maxWireVersion(topologyOrServer) {
+  if (topologyOrServer) {
+    if (topologyOrServer.ismaster) {
+      return topologyOrServer.ismaster.maxWireVersion;
+    }
+
+    if (typeof topologyOrServer.lastIsMaster === 'function') {
+      const lastIsMaster = topologyOrServer.lastIsMaster();
+      if (lastIsMaster) {
+        return lastIsMaster.maxWireVersion;
+      }
+    }
+
+    if (topologyOrServer.description) {
+      return topologyOrServer.description.maxWireVersion;
+    }
+  }
+
+  return 0;
+}
+
+/*
+ * Checks that collation is supported by server.
+ *
+ * @param {Server} [server] to check against
+ * @param {object} [cmd] object where collation may be specified
+ * @param {function} [callback] callback function
+ * @return true if server does not support collation
+ */
+function collationNotSupported(server, cmd) {
+  return cmd && cmd.collation && maxWireVersion(server) < 5;
+}
+
+/**
+ * Checks if a given value is a Promise
+ *
+ * @param {*} maybePromise
+ * @return true if the provided value is a Promise
+ */
+function isPromiseLike(maybePromise) {
+  return maybePromise && typeof maybePromise.then === 'function';
+}
+
+/**
+ * Applies the function `eachFn` to each item in `arr`, in parallel.
+ *
+ * @param {array} arr an array of items to asynchronusly iterate over
+ * @param {function} eachFn A function to call on each item of the array. The callback signature is `(item, callback)`, where the callback indicates iteration is complete.
+ * @param {function} callback The callback called after every item has been iterated
+ */
+function eachAsync(arr, eachFn, callback) {
+  arr = arr || [];
+
+  let idx = 0;
+  let awaiting = 0;
+  for (idx = 0; idx < arr.length; ++idx) {
+    awaiting++;
+    eachFn(arr[idx], eachCallback);
+  }
+
+  if (awaiting === 0) {
+    callback();
+    return;
+  }
+
+  function eachCallback(err) {
+    awaiting--;
+    if (err) {
+      callback(err);
+      return;
+    }
+
+    if (idx === arr.length && awaiting <= 0) {
+      callback();
+    }
+  }
+}
+
+function eachAsyncSeries(arr, eachFn, callback) {
+  arr = arr || [];
+
+  let idx = 0;
+  let awaiting = arr.length;
+  if (awaiting === 0) {
+    callback();
+    return;
+  }
+
+  function eachCallback(err) {
+    idx++;
+    awaiting--;
+    if (err) {
+      callback(err);
+      return;
+    }
+
+    if (idx === arr.length && awaiting <= 0) {
+      callback();
+      return;
+    }
+
+    eachFn(arr[idx], eachCallback);
+  }
+
+  eachFn(arr[idx], eachCallback);
+}
+
+function isUnifiedTopology(topology) {
+  return topology.description != null;
+}
+
+function arrayStrictEqual(arr, arr2) {
+  if (!Array.isArray(arr) || !Array.isArray(arr2)) {
+    return false;
+  }
+
+  return arr.length === arr2.length && arr.every((elt, idx) => elt === arr2[idx]);
+}
+
+function tagsStrictEqual(tags, tags2) {
+  const tagsKeys = Object.keys(tags);
+  const tags2Keys = Object.keys(tags2);
+  return tagsKeys.length === tags2Keys.length && tagsKeys.every(key => tags2[key] === tags[key]);
+}
+
+function errorStrictEqual(lhs, rhs) {
+  if (lhs === rhs) {
+    return true;
+  }
+
+  if ((lhs == null && rhs != null) || (lhs != null && rhs == null)) {
+    return false;
+  }
+
+  if (lhs.constructor.name !== rhs.constructor.name) {
+    return false;
+  }
+
+  if (lhs.message !== rhs.message) {
+    return false;
+  }
+
+  return true;
+}
+
+function makeStateMachine(stateTable) {
+  return function stateTransition(target, newState) {
+    const legalStates = stateTable[target.s.state];
+    if (legalStates && legalStates.indexOf(newState) < 0) {
+      throw new TypeError(
+        `illegal state transition from [${target.s.state}] => [${newState}], allowed: [${legalStates}]`
+      );
+    }
+
+    target.emit('stateChanged', target.s.state, newState);
+    target.s.state = newState;
+  };
+}
+
+function makeClientMetadata(options) {
+  options = options || {};
+
+  const metadata = {
+    driver: {
+      name: 'nodejs',
+      version: require('../../package.json').version
+    },
+    os: {
+      type: os.type(),
+      name: process.platform,
+      architecture: process.arch,
+      version: os.release()
+    },
+    platform: `'Node.js ${process.version}, ${os.endianness} (${
+      options.useUnifiedTopology ? 'unified' : 'legacy'
+    })`
+  };
+
+  // support optionally provided wrapping driver info
+  if (options.driverInfo) {
+    if (options.driverInfo.name) {
+      metadata.driver.name = `${metadata.driver.name}|${options.driverInfo.name}`;
+    }
+
+    if (options.driverInfo.version) {
+      metadata.version = `${metadata.driver.version}|${options.driverInfo.version}`;
+    }
+
+    if (options.driverInfo.platform) {
+      metadata.platform = `${metadata.platform}|${options.driverInfo.platform}`;
+    }
+  }
+
+  if (options.appname) {
+    // MongoDB requires the appname not exceed a byte length of 128
+    const buffer = Buffer.from(options.appname);
+    metadata.application = {
+      name: buffer.length > 128 ? buffer.slice(0, 128).toString('utf8') : options.appname
+    };
+  }
+
+  return metadata;
+}
+
+const noop = () => {};
+
+module.exports = {
+  uuidV4,
+  relayEvents,
+  collationNotSupported,
+  retrieveEJSON,
+  retrieveKerberos,
+  maxWireVersion,
+  isPromiseLike,
+  eachAsync,
+  eachAsyncSeries,
+  isUnifiedTopology,
+  arrayStrictEqual,
+  tagsStrictEqual,
+  errorStrictEqual,
+  makeStateMachine,
+  makeClientMetadata,
+  noop
+};