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39 lines
1.5 KiB
TypeScript
39 lines
1.5 KiB
TypeScript
/*
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* SPDX-FileCopyrightText: 2023 The HedgeDoc developers (see AUTHORS file)
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*
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* SPDX-License-Identifier: AGPL-3.0-only
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*/
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import type { FrontmatterExtractionResult } from './types.js'
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const FRONTMATTER_BEGIN_REGEX = /^-{3,}$/
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const FRONTMATTER_END_REGEX = /^(?:-{3,}|\.{3,})$/
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/**
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* Extracts a frontmatter block from a given multiline string.
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* A valid frontmatter block requires the content to start with a line containing at least three dashes.
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* The block is terminated by a line containing the same amount of dashes or dots as the first line.
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* @param lines The lines from which the frontmatter should be extracted.
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* @return { isPresent } false if no frontmatter block could be found, true if a block was found.
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* { rawFrontmatterText } if a block was found, this property contains the extracted text without the fencing.
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* { frontmatterLines } if a block was found, this property contains the number of lines to skip from the
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* given multiline string for retrieving the non-frontmatter content.
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*/
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export const extractFrontmatter = (
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lines: string[]
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): FrontmatterExtractionResult | undefined => {
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if (lines.length < 2 || !FRONTMATTER_BEGIN_REGEX.test(lines[0])) {
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return undefined
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}
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for (let i = 1; i < lines.length; i++) {
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if (
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lines[i].length === lines[0].length &&
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FRONTMATTER_END_REGEX.test(lines[i])
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) {
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return {
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rawText: lines.slice(1, i).join('\n'),
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lineOffset: i + 1
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}
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}
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}
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return undefined
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}
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