133 lines
4.2 KiB
JavaScript
133 lines
4.2 KiB
JavaScript
'use strict';
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const util = require('util');
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const { SPLAT } = require('triple-beam');
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/**
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* Captures the number of format (i.e. %s strings) in a given string.
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* Based on `util.format`, see Node.js source:
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* https://github.com/nodejs/node/blob/b1c8f15c5f169e021f7c46eb7b219de95fe97603/lib/util.js#L201-L230
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* @type {RegExp}
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*/
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const formatRegExp = /%[scdjifoO%]/g;
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/**
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* Captures the number of escaped % signs in a format string (i.e. %s strings).
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* @type {RegExp}
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*/
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const escapedPercent = /%%/g;
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class Splatter {
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constructor(opts) {
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this.options = opts;
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}
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/**
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* Check to see if tokens <= splat.length, assign { splat, meta } into the
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* `info` accordingly, and write to this instance.
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*
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* @param {Info} info Logform info message.
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* @param {String[]} tokens Set of string interpolation tokens.
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* @returns {Info} Modified info message
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* @private
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*/
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_splat(info, tokens) {
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const msg = info.message;
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const splat = info[SPLAT] || info.splat || [];
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const percents = msg.match(escapedPercent);
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const escapes = percents && percents.length || 0;
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// The expected splat is the number of tokens minus the number of escapes
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// e.g.
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// - { expectedSplat: 3 } '%d %s %j'
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// - { expectedSplat: 5 } '[%s] %d%% %d%% %s %j'
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//
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// Any "meta" will be arugments in addition to the expected splat size
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// regardless of type. e.g.
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//
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// logger.log('info', '%d%% %s %j', 100, 'wow', { such: 'js' }, { thisIsMeta: true });
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// would result in splat of four (4), but only three (3) are expected. Therefore:
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//
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// extraSplat = 3 - 4 = -1
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// metas = [100, 'wow', { such: 'js' }, { thisIsMeta: true }].splice(-1, -1 * -1);
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// splat = [100, 'wow', { such: 'js' }]
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const expectedSplat = tokens.length - escapes;
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const extraSplat = expectedSplat - splat.length;
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const metas = extraSplat < 0
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? splat.splice(extraSplat, -1 * extraSplat)
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: [];
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// Now that { splat } has been separated from any potential { meta }. we
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// can assign this to the `info` object and write it to our format stream.
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// If the additional metas are **NOT** objects or **LACK** enumerable properties
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// you are going to have a bad time.
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const metalen = metas.length;
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if (metalen) {
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for (let i = 0; i < metalen; i++) {
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Object.assign(info, metas[i]);
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}
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}
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info.message = util.format(msg, ...splat);
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return info;
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}
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/**
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* Transforms the `info` message by using `util.format` to complete
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* any `info.message` provided it has string interpolation tokens.
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* If no tokens exist then `info` is immutable.
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*
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* @param {Info} info Logform info message.
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* @param {Object} opts Options for this instance.
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* @returns {Info} Modified info message
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*/
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transform(info) {
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const msg = info.message;
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const splat = info[SPLAT] || info.splat;
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// No need to process anything if splat is undefined
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if (!splat || !splat.length) {
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return info;
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}
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// Extract tokens, if none available default to empty array to
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// ensure consistancy in expected results
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const tokens = msg && msg.match && msg.match(formatRegExp);
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// This condition will take care of inputs with info[SPLAT]
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// but no tokens present
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if (!tokens && (splat || splat.length)) {
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const metas = splat.length > 1
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? splat.splice(0)
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: splat;
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// Now that { splat } has been separated from any potential { meta }. we
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// can assign this to the `info` object and write it to our format stream.
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// If the additional metas are **NOT** objects or **LACK** enumerable properties
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// you are going to have a bad time.
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const metalen = metas.length;
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if (metalen) {
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for (let i = 0; i < metalen; i++) {
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Object.assign(info, metas[i]);
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}
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}
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return info;
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}
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if (tokens) {
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return this._splat(info, tokens);
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}
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return info;
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}
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}
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/*
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* function splat (info)
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* Returns a new instance of the splat format TransformStream
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* which performs string interpolation from `info` objects. This was
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* previously exposed implicitly in `winston < 3.0.0`.
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*/
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module.exports = opts => new Splatter(opts);
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