88 lines
2.3 KiB
JavaScript
88 lines
2.3 KiB
JavaScript
/**
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* @typedef {import('hast').Element} Element
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* @typedef {import('hast').Properties} Properties
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*/
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/**
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* @template {string} SimpleSelector
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* Selector type.
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* @template {string} DefaultTagName
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* Default tag name.
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* @typedef {(
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* SimpleSelector extends ''
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* ? DefaultTagName
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* : SimpleSelector extends `${infer TagName}.${infer Rest}`
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* ? ExtractTagName<TagName, DefaultTagName>
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* : SimpleSelector extends `${infer TagName}#${infer Rest}`
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* ? ExtractTagName<TagName, DefaultTagName>
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* : SimpleSelector extends string
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* ? SimpleSelector
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* : DefaultTagName
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* )} ExtractTagName
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* Extract tag name from a simple selector.
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*/
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const search = /[#.]/g
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/**
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* Create a hast element from a simple CSS selector.
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*
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* @template {string} Selector
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* Type of selector.
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* @template {string} [DefaultTagName='div']
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* Type of default tag name (default: `'div'`).
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* @param {Selector | null | undefined} [selector]
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* Simple CSS selector (optional).
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*
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* Can contain a tag name (`foo`), classes (`.bar`), and an ID (`#baz`).
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* Multiple classes are allowed.
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* Uses the last ID if multiple IDs are found.
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* @param {DefaultTagName | null | undefined} [defaultTagName='div']
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* Tag name to use if `selector` does not specify one (default: `'div'`).
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* @returns {Element & {tagName: ExtractTagName<Selector, DefaultTagName>}}
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* Built element.
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*/
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export function parseSelector(selector, defaultTagName) {
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const value = selector || ''
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/** @type {Properties} */
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const props = {}
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let start = 0
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/** @type {string | undefined} */
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let previous
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/** @type {string | undefined} */
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let tagName
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while (start < value.length) {
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search.lastIndex = start
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const match = search.exec(value)
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const subvalue = value.slice(start, match ? match.index : value.length)
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if (subvalue) {
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if (!previous) {
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tagName = subvalue
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} else if (previous === '#') {
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props.id = subvalue
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} else if (Array.isArray(props.className)) {
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props.className.push(subvalue)
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} else {
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props.className = [subvalue]
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}
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start += subvalue.length
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}
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if (match) {
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previous = match[0]
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start++
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}
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}
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return {
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type: 'element',
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// @ts-expect-error: tag name is parsed.
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tagName: tagName || defaultTagName || 'div',
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properties: props,
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children: []
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}
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}
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