55 lines
1.4 KiB
Plaintext
55 lines
1.4 KiB
Plaintext
/**
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* Copyright (c) 2017-present, Facebook, Inc.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @flow strict
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*/
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import invariant from './invariant';
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/**
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* fixes indentation by removing leading spaces and tabs from each line
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*/
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function fixIndent(str: string): string {
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const trimmedStr = str
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.replace(/^\n*/m, '') // remove leading newline
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.replace(/[ \t]*$/, ''); // remove trailing spaces and tabs
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const indentMatch = /^[ \t]*/.exec(trimmedStr);
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invariant(Array.isArray(indentMatch));
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const indent = indentMatch[0]; // figure out indent
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return trimmedStr.replace(RegExp('^' + indent, 'mg'), ''); // remove indent
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}
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/**
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* An ES6 string tag that fixes indentation. Also removes leading newlines
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* and trailing spaces and tabs, but keeps trailing newlines.
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*
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* Example usage:
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* const str = dedent`
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* {
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* test
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* }
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* `
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* str === "{\n test\n}\n";
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*/
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export default function dedent(
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strings: string | Array<string>,
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...values: Array<string>
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): string {
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// when used as an ordinary function, allow passing a singleton string
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const strArray = typeof strings === 'string' ? [strings] : strings;
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const numValues = values.length;
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const str = strArray.reduce((prev, cur, index) => {
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let next = prev + cur;
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if (index < numValues) {
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next += values[index]; // interpolation
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}
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return next;
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}, '');
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return fixIndent(str);
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}
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