65 lines
1.6 KiB
Plaintext
65 lines
1.6 KiB
Plaintext
/**
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* Copyright (c) 2015-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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/**
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* Produces the value of a block string from its parsed raw value, similar to
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* Coffeescript's block string, Python's docstring trim or Ruby's strip_heredoc.
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*
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* This implements the GraphQL spec's BlockStringValue() static algorithm.
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*/
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export default function blockStringValue(rawString: string): string {
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// Expand a block string's raw value into independent lines.
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const lines = rawString.split(/\r\n|[\n\r]/g);
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// Remove common indentation from all lines but first.
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let commonIndent = null;
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for (let i = 1; i < lines.length; i++) {
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const line = lines[i];
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const indent = leadingWhitespace(line);
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if (
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indent < line.length &&
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(commonIndent === null || indent < commonIndent)
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) {
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commonIndent = indent;
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if (commonIndent === 0) {
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break;
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}
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}
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}
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if (commonIndent) {
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for (let i = 1; i < lines.length; i++) {
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lines[i] = lines[i].slice(commonIndent);
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}
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}
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// Remove leading and trailing blank lines.
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while (lines.length > 0 && isBlank(lines[0])) {
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lines.shift();
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}
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while (lines.length > 0 && isBlank(lines[lines.length - 1])) {
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lines.pop();
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}
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// Return a string of the lines joined with U+000A.
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return lines.join('\n');
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}
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function leadingWhitespace(str) {
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let i = 0;
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while (i < str.length && (str[i] === ' ' || str[i] === '\t')) {
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i++;
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}
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return i;
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}
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function isBlank(str) {
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return leadingWhitespace(str) === str.length;
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}
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