52 lines
1.3 KiB
Plaintext
52 lines
1.3 KiB
Plaintext
/**
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* @typedef {import('hast').Parents} Parents
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* @typedef {import('hast').RootContent} RootContent
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*/
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import {whitespace} from 'hast-util-whitespace'
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export const siblingAfter = siblings(1)
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export const siblingBefore = siblings(-1)
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/** @type {Array<RootContent>} */
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const emptyChildren = []
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/**
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* Factory to check siblings in a direction.
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*
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* @param {number} increment
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*/
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function siblings(increment) {
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return sibling
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/**
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* Find applicable siblings in a direction.
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*
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* @template {Parents} Parent
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* Parent type.
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* @param {Parent | undefined} parent
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* Parent.
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* @param {number | undefined} index
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* Index of child in `parent`.
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* @param {boolean | undefined} [includeWhitespace=false]
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* Whether to include whitespace (default: `false`).
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* @returns {Parent extends {children: Array<infer Child>} ? Child | undefined : never}
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* Child of parent.
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*/
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function sibling(parent, index, includeWhitespace) {
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const siblings = parent ? parent.children : emptyChildren
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let offset = (index || 0) + increment
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let next = siblings[offset]
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if (!includeWhitespace) {
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while (next && whitespace(next)) {
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offset += increment
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next = siblings[offset]
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}
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}
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// @ts-expect-error: it’s a correct child.
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return next
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}
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}
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