node/lib/console.js at master · anchnk/node · GitHub

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// Copyright Joyent, Inc. and other Node contributors.

// Permission is hereby granted, free of charge, to any person obtaining a

// copy of this software and associated documentation files (the

// "Software"), to deal in the Software without restriction, including

// without limitation the rights to use, copy, modify, merge, publish,

// distribute, sublicense, and/or sell copies of the Software, and to permit

// persons to whom the Software is furnished to do so, subject to the

// following conditions:

// The above copyright notice and this permission notice shall be included

// in all copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS

// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN

// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,

// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR

// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE

// USE OR OTHER DEALINGS IN THE SOFTWARE.

'use strict';

const util = require('util');

function Console(stdout, stderr, ignoreErrors = true) {

if (!(this instanceof Console)) {

return new Console(stdout, stderr, ignoreErrors);

}

if (!stdout || typeof stdout.write !== 'function') {

throw new TypeError('Console expects a writable stream instance');

}

if (!stderr) {

stderr = stdout;

} else if (typeof stderr.write !== 'function') {

throw new TypeError('Console expects writable stream instances');

}

var prop = {

writable: true,

enumerable: false,

configurable: true

};

prop.value = stdout;

Object.defineProperty(this, '_stdout', prop);

prop.value = stderr;

Object.defineProperty(this, '_stderr', prop);

prop.value = ignoreErrors;

Object.defineProperty(this, '_ignoreErrors', prop);

prop.value = new Map();

Object.defineProperty(this, '_times', prop);

prop.value = createWriteErrorHandler(stdout);

Object.defineProperty(this, '_stdoutErrorHandler', prop);

prop.value = createWriteErrorHandler(stderr);

Object.defineProperty(this, '_stderrErrorHandler', prop);

// bind the prototype functions to this Console instance

var keys = Object.keys(Console.prototype);

for (var v = 0; v < keys.length; v++) {

var k = keys[v];

this[k] = this[k].bind(this);

}

// Make a function that can serve as the callback passed to `stream.write()`.

function createWriteErrorHandler(stream) {

return (err) => {

// This conditional evaluates to true if and only if there was an error

// that was not already emitted (which happens when the _write callback

// is invoked asynchronously).

if (err && !stream._writableState.errorEmitted) {

// If there was an error, it will be emitted on `stream` as

// an `error` event. Adding a `once` listener will keep that error

// from becoming an uncaught exception, but since the handler is

// removed after the event, non-console.* writes won’t be affected.

stream.once('error', noop);

}

};

}

function write(ignoreErrors, stream, string, errorhandler) {

if (!ignoreErrors) return stream.write(string);

// There may be an error occurring synchronously (e.g. for files or TTYs

// on POSIX systems) or asynchronously (e.g. pipes on POSIX systems), so

// handle both situations.

try {

// Add and later remove a noop error handler to catch synchronous errors.

stream.once('error', noop);

stream.write(string, errorhandler);

} catch (e) {

// Sorry, there’s no proper way to pass along the error here.

} finally {

stream.removeListener('error', noop);

}

// As of v8 5.0.71.32, the combination of rest param, template string

// and .apply(null, args) benchmarks consistently faster than using

// the spread operator when calling util.format.

Console.prototype.log = function log(...args) {

write(this._ignoreErrors,

this._stdout,

`${util.format.apply(null, args)}\n`,

this._stdoutErrorHandler);

};

Console.prototype.info = Console.prototype.log;

Console.prototype.warn = function warn(...args) {

write(this._ignoreErrors,

this._stderr,

`${util.format.apply(null, args)}\n`,

this._stderrErrorHandler);

};

Console.prototype.error = Console.prototype.warn;

Console.prototype.dir = function dir(object, options) {

options = Object.assign({customInspect: false}, options);

write(this._ignoreErrors,

this._stdout,

`${util.inspect(object, options)}\n`,

this._stdoutErrorHandler);

};

Console.prototype.time = function time(label) {

this._times.set(label, process.hrtime());

};

Console.prototype.timeEnd = function timeEnd(label) {

const time = this._times.get(label);

if (!time) {

process.emitWarning(`No such label '${label}' for console.timeEnd()`);

return;

}

const duration = process.hrtime(time);

const ms = duration[0] * 1000 + duration[1] / 1e6;

this.log('%s: %sms', label, ms.toFixed(3));

this._times.delete(label);

};

Console.prototype.trace = function trace(...args) {

// TODO probably can to do this better with V8's debug object once that is

// exposed.

var err = new Error();

err.name = 'Trace';

err.message = util.format.apply(null, args);

Error.captureStackTrace(err, trace);

this.error(err.stack);

};

Console.prototype.assert = function assert(expression, ...args) {

if (!expression) {

require('assert').ok(false, util.format.apply(null, args));

}

};

module.exports = new Console(process.stdout, process.stderr);

module.exports.Console = Console;

function noop() {}

node/lib/console.js at master · anchnk/node · GitHub

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