53 lines
1.1 KiB
JavaScript
53 lines
1.1 KiB
JavaScript
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'use strict';
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/*
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* Displays a helpful message and the source of
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* the format when it is invalid.
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*/
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class InvalidFormatError extends Error {
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constructor(formatFn) {
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super(`Format functions must be synchronous taking a two arguments: (info, opts)
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Found: ${formatFn.toString().split('\n')[0]}\n`);
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Error.captureStackTrace(this, InvalidFormatError);
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}
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}
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/*
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* function format (formatFn)
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* Returns a create function for the `formatFn`.
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*/
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module.exports = formatFn => {
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if (formatFn.length > 2) {
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throw new InvalidFormatError(formatFn);
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}
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/*
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* function Format (options)
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* Base prototype which calls a `_format`
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* function and pushes the result.
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*/
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function Format(options = {}) {
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this.options = options;
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}
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Format.prototype.transform = formatFn;
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//
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// Create a function which returns new instances of
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// FormatWrap for simple syntax like:
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//
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// require('winston').formats.json();
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//
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function createFormatWrap(opts) {
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return new Format(opts);
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}
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//
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// Expose the FormatWrap through the create function
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// for testability.
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//
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createFormatWrap.Format = Format;
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return createFormatWrap;
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};
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