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const slugify = (s) => encodeURIComponent(String(s).trim().toLowerCase().replace(/\s+/g, '-'))
const position = {
false: 'push',
true: 'unshift'
}
const hasProp = Object.prototype.hasOwnProperty
const permalinkHref = slug => `#${slug}`
const renderPermalink = (slug, opts, state, idx) => {
const space = () => Object.assign(new state.Token('text', '', 0), { content: ' ' })
const linkTokens = [
Object.assign(new state.Token('link_open', 'a', 1), {
attrs: [
['class', opts.permalinkClass],
['href', opts.permalinkHref(slug, state)],
['aria-hidden', 'true']
]
}),
Object.assign(new state.Token('html_block', '', 0), { content: opts.permalinkSymbol }),
new state.Token('link_close', 'a', -1)
]
// `push` or `unshift` according to position option.
// Space is at the opposite side.
linkTokens[position[!opts.permalinkBefore]](space())
state.tokens[idx + 1].children[position[opts.permalinkBefore]](...linkTokens)
}
const uniqueSlug = (slug, slugs) => {
let uniq = slug
let i = 2
while (hasProp.call(slugs, uniq)) uniq = `${slug}-${i++}`
slugs[uniq] = true
return uniq
}
const isLevelSelectedNumber = selection => level => level >= selection
const isLevelSelectedArray = selection => level => selection.includes(level)
const anchor = (md, opts) => {
opts = Object.assign({}, anchor.defaults, opts)
md.core.ruler.push('anchor', state => {
const slugs = {}
const tokens = state.tokens
const isLevelSelected = Array.isArray(opts.level)
? isLevelSelectedArray(opts.level)
: isLevelSelectedNumber(opts.level)
tokens
.filter(token => token.type === 'heading_open')
.filter(token => isLevelSelected(Number(token.tag.substr(1))))
.forEach(token => {
// Aggregate the next token children text.
const title = tokens[tokens.indexOf(token) + 1].children
.filter(token => token.type === 'text' || token.type === 'code_inline')
.reduce((acc, t) => acc + t.content, '')
let slug = token.attrGet('id')
if (slug == null) {
slug = uniqueSlug(opts.slugify(title), slugs)
token.attrPush(['id', slug])
}
if (opts.permalink) {
opts.renderPermalink(slug, opts, state, tokens.indexOf(token))
}
if (opts.callback) {
opts.callback(token, { slug, title })
}
})
})
}
anchor.defaults = {
level: 1,
slugify,
permalink: false,
renderPermalink,
permalinkClass: 'header-anchor',
permalinkSymbol: '¶',
permalinkBefore: false,
permalinkHref
}
module.exports = anchor
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