171 lines
4.5 KiB
JavaScript
171 lines
4.5 KiB
JavaScript
/**
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* @typedef {import('mdast').Literal} Literal
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* @typedef {import('mdast-util-from-markdown').Extension} FromMarkdownExtension
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* @typedef {import('mdast-util-from-markdown').CompileContext} CompileContext
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* @typedef {import('mdast-util-from-markdown').Handle} FromMarkdownHandle
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* @typedef {import('mdast-util-to-markdown').Options} ToMarkdownExtension
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*
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* @typedef {import('micromark-extension-frontmatter').Options} Options
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* @typedef {import('micromark-extension-frontmatter/matters.js').Matter} Matter
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* @typedef {import('micromark-extension-frontmatter/matters.js').Info} Info
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*/
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import {matters} from 'micromark-extension-frontmatter/matters.js'
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/**
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* Create an extension for `mdast-util-from-markdown`.
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*
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* @param {Options | null | undefined} [options]
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* Configuration.
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* @returns {FromMarkdownExtension}
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* Extension for `mdast-util-from-markdown`.
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*/
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export function frontmatterFromMarkdown(options) {
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// @ts-expect-error: `micromark-extension-frontmatter` should fix types to
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// accept `null` as options.
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const settings = matters(options)
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/** @type {FromMarkdownExtension['enter']} */
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const enter = {}
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/** @type {FromMarkdownExtension['exit']} */
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const exit = {}
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let index = -1
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while (++index < settings.length) {
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const matter = settings[index]
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enter[matter.type] = opener(matter)
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exit[matter.type] = close
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exit[matter.type + 'Value'] = value
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}
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return {enter, exit}
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}
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/**
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* @param {Matter} matter
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* @returns {FromMarkdownHandle} enter
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*/
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function opener(matter) {
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return open
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/**
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* @this {CompileContext}
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* @type {FromMarkdownHandle}
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*/
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function open(token) {
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// @ts-expect-error: custom.
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this.enter({type: matter.type, value: ''}, token)
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this.buffer()
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}
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}
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/**
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* @this {CompileContext}
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* @type {FromMarkdownHandle}
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*/
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function close(token) {
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const data = this.resume()
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const node = /** @type {Literal} */ (this.exit(token))
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// Remove the initial and final eol.
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node.value = data.replace(/^(\r?\n|\r)|(\r?\n|\r)$/g, '')
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}
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/**
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* @this {CompileContext}
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* @type {FromMarkdownHandle}
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*/
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function value(token) {
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this.config.enter.data.call(this, token)
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this.config.exit.data.call(this, token)
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}
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/**
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* Create an extension for `mdast-util-to-markdown`.
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*
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* @param {Options | null | undefined} [options]
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* Configuration.
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* @returns {ToMarkdownExtension}
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* Extension for `mdast-util-to-markdown`.
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*/
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export function frontmatterToMarkdown(options) {
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// To do: use an extension object with `satisfies` later.
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/** @type {ToMarkdownExtension['unsafe']} */
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const unsafe = []
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/** @type {ToMarkdownExtension['handlers']} */
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const handlers = {}
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// @ts-expect-error: `micromark-extension-frontmatter` should fix types to
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// accept `null` as options.
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const settings = matters(options)
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let index = -1
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while (++index < settings.length) {
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const matter = settings[index]
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// @ts-expect-error: this can add custom frontmatter nodes.
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// Typing those is the responsibility of the end user.
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handlers[matter.type] = handler(matter)
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// To do: idea: perhaps make this smarter, with an `after` of the second char?
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unsafe.push({atBreak: true, character: fence(matter, 'open').charAt(0)})
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}
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return {unsafe, handlers}
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}
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/**
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* Create a handle that can serialize a frontmatter node as markdown.
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*
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* @param {Matter} matter
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* Structure.
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* @returns {(node: Literal) => string} enter
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* Handler.
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*/
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function handler(matter) {
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const open = fence(matter, 'open')
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const close = fence(matter, 'close')
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return handle
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/**
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* Serialize a frontmatter node as markdown.
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*
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* @param {Literal} node
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* Node to serialize.
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* @returns {string}
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* Serialized node.
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*/
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function handle(node) {
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return open + (node.value ? '\n' + node.value : '') + '\n' + close
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}
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}
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/**
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* Get an `open` or `close` fence.
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*
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* @param {Matter} matter
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* Structure.
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* @param {'open' | 'close'} prop
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* Field to get.
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* @returns {string}
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* Fence.
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*/
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function fence(matter, prop) {
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return matter.marker
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? pick(matter.marker, prop).repeat(3)
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: // @ts-expect-error: They’re mutually exclusive.
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pick(matter.fence, prop)
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}
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/**
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* Take `open` or `close` fields when schema is an info object, or use the
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* given value when it is a string.
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*
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* @param {Info | string} schema
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* Info object or value.
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* @param {'open' | 'close'} prop
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* Field to get.
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* @returns {string}
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* Thing to use for the opening or closing.
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*/
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function pick(schema, prop) {
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return typeof schema === 'string' ? schema : schema[prop]
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}
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