127 lines
3.5 KiB
JavaScript
127 lines
3.5 KiB
JavaScript
/**
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* @typedef {'toml' | 'yaml'} Preset
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* Known name of a frontmatter style.
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*
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* @typedef Info
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* Sequence.
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*
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* Depending on how this structure is used, it reflects a marker or a fence.
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* @property {string} close
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* Closing.
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* @property {string} open
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* Opening.
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*
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* @typedef MatterProps
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* Fields describing a kind of matter.
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* @property {string} type
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* Node type to tokenize as.
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* @property {boolean | null | undefined} [anywhere=false]
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* Whether matter can be found anywhere in the document, normally, only matter
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* at the start of the document is recognized.
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*
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* > 👉 **Note**: using this is a terrible idea.
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* > It’s called frontmatter, not matter-in-the-middle or so.
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* > This makes your markdown less portable.
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*
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* @typedef MarkerProps
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* Marker configuration.
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* @property {Info | string} marker
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* Character repeated 3 times, used as complete fences.
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*
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* For example the character `'-'` will result in `'---'` being used as the
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* fence
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* Pass `open` and `close` to specify different characters for opening and
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* closing fences.
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* @property {never} [fence]
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* If `marker` is set, `fence` must not be set.
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*
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* @typedef FenceProps
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* Fence configuration.
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* @property {Info | string} fence
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* Complete fences.
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*
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* This can be used when fences contain different characters or lengths
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* other than 3.
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* Pass `open` and `close` to interface to specify different characters for opening and
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* closing fences.
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* @property {never} [marker]
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* If `fence` is set, `marker` must not be set.
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*
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* @typedef {(MatterProps & FenceProps) | (MatterProps & MarkerProps)} Matter
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* Fields describing a kind of matter.
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*
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* > 👉 **Note**: using `anywhere` is a terrible idea.
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* > It’s called frontmatter, not matter-in-the-middle or so.
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* > This makes your markdown less portable.
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*
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* > 👉 **Note**: `marker` and `fence` are mutually exclusive.
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* > If `marker` is set, `fence` must not be set, and vice versa.
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*
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* @typedef {Matter | Preset | Array<Matter | Preset>} Options
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* Configuration.
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*/
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import {fault} from 'fault'
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const own = {}.hasOwnProperty
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const markers = {yaml: '-', toml: '+'}
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/**
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* Simplify options by normalizing them to an array of matters.
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*
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* @param {Options | null | undefined} [options='yaml']
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* Configuration (default: `'yaml'`).
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* @returns {Array<Matter>}
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* List of matters.
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*/
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export function toMatters(options) {
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/** @type {Array<Matter>} */
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const result = []
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let index = -1
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/** @type {Array<Matter | Preset>} */
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const presetsOrMatters = Array.isArray(options)
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? options
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: options
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? [options]
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: ['yaml']
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while (++index < presetsOrMatters.length) {
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result[index] = matter(presetsOrMatters[index])
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}
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return result
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}
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/**
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* Simplify an option.
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*
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* @param {Matter | Preset} option
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* Configuration.
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* @returns {Matter}
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* Matter.
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*/
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function matter(option) {
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let result = option
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if (typeof result === 'string') {
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if (!own.call(markers, result)) {
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throw fault('Missing matter definition for `%s`', result)
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}
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result = {type: result, marker: markers[result]}
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} else if (typeof result !== 'object') {
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throw fault('Expected matter to be an object, not `%j`', result)
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}
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if (!own.call(result, 'type')) {
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throw fault('Missing `type` in matter `%j`', result)
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}
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if (!own.call(result, 'fence') && !own.call(result, 'marker')) {
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throw fault('Missing `marker` or `fence` in matter `%j`', result)
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}
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return result
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}
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