lib/gfm/link.js
// CommonMark specifies that links have no whitespace between the label and
// destination, e.g.:
//
// [link text](path/to/the/thing)
//
// However, GitHub allows you to put whitespace between the `]` and `(`
// characters, like so:
//
// [link text] (path/to/the/thing)
//
// This is against CommonMark because it's ambiguous. Consider a link reference
// followed by a parenthetical statement:
//
// [link text] (parenthetical statement)
//
// [link text]: path/to/the/thing
//
// CommonMark renders: <a href="path/to/the/thing">link text</a>
// GitHub renders: <a href="parenthetical%20statement">link text</a>
//
// To account for the difference, we need to override markdown-it's link rule.
// This file is a copy of the original markdown-it source, plus the necessary
// modifications, wrapped as a markdown-it plugin.
// Process [link](<to> "stuff")
'use strict'
module.exports = function (md) {
md.inline.ruler.at('link', link)
}
function link (state, silent) {
var attrs
var code
var label
var labelEnd
var labelStart
var pos
var res
var ref
var title
var token
var href = ''
var oldPos = state.pos
var max = state.posMax
var start = state.pos
var parseReference = true
var isSpace = state.md.utils.isSpace
var normalizeReference = state.md.utils.normalizeReference
if (state.src.charCodeAt(state.pos) !== 0x5B/* [ */) { return false }
labelStart = state.pos + 1
labelEnd = state.md.helpers.parseLinkLabel(state, state.pos, true)
// parser failed to find ']', so it's not a valid link
if (labelEnd < 0) { return false }
pos = labelEnd + 1
// BEGIN CUSTOM MODIFICATION
// look ahead to see if the next non-whitespace character is '(', and if
// it is, skip the whitespace
for (; pos < max; pos++) {
code = state.src.charCodeAt(pos)
if (!isSpace(code) && code !== 0x0A) { break }
}
if (pos < max && state.src.charCodeAt(pos) !== 0x28) { pos = labelEnd + 1 }
// END CUSTOM MODIFICATION
if (pos < max && state.src.charCodeAt(pos) === 0x28/* ( */) {
//
// Inline link
//
// might have found a valid shortcut link, disable reference parsing
parseReference = false
// [link]( <href> "title" )
// ^^ skipping these spaces
pos++
for (; pos < max; pos++) {
code = state.src.charCodeAt(pos)
if (!isSpace(code) && code !== 0x0A) { break }
}
if (pos >= max) { return false }
// [link]( <href> "title" )
// ^^^^^^ parsing link destination
start = pos
res = state.md.helpers.parseLinkDestination(state.src, pos, state.posMax)
if (res.ok) {
href = state.md.normalizeLink(res.str)
if (state.md.validateLink(href)) {
pos = res.pos
} else {
href = ''
}
}
// [link]( <href> "title" )
// ^^ skipping these spaces
start = pos
for (; pos < max; pos++) {
code = state.src.charCodeAt(pos)
if (!isSpace(code) && code !== 0x0A) { break }
}
// [link]( <href> "title" )
// ^^^^^^^ parsing link title
res = state.md.helpers.parseLinkTitle(state.src, pos, state.posMax)
if (pos < max && start !== pos && res.ok) {
title = res.str
pos = res.pos
// [link]( <href> "title" )
// ^^ skipping these spaces
for (; pos < max; pos++) {
code = state.src.charCodeAt(pos)
if (!isSpace(code) && code !== 0x0A) { break }
}
} else {
title = ''
}
if (pos >= max || state.src.charCodeAt(pos) !== 0x29/* ) */) {
// parsing a valid shortcut link failed, fallback to reference
parseReference = true
}
pos++
}
if (parseReference) {
//
// Link reference
//
if (typeof state.env.references === 'undefined') { return false }
if (pos < max && state.src.charCodeAt(pos) === 0x5B/* [ */) {
start = pos + 1
pos = state.md.helpers.parseLinkLabel(state, pos)
if (pos >= 0) {
label = state.src.slice(start, pos++)
} else {
pos = labelEnd + 1
}
} else {
pos = labelEnd + 1
}
// covers label === '' and label === undefined
// (collapsed reference link and shortcut reference link respectively)
if (!label) { label = state.src.slice(labelStart, labelEnd) }
ref = state.env.references[normalizeReference(label)]
if (!ref) {
state.pos = oldPos
return false
}
href = ref.href
title = ref.title
}
//
// We found the end of the link, and know for a fact it's a valid link;
// so all that's left to do is to call tokenizer.
//
if (!silent) {
state.pos = labelStart
state.posMax = labelEnd
token = state.push('link_open', 'a', 1)
token.attrs = attrs = [ [ 'href', href ] ]
if (title) {
attrs.push([ 'title', title ])
}
state.md.inline.tokenize(state)
token = state.push('link_close', 'a', -1)
}
state.pos = pos
state.posMax = max
return true
}