markdown-it/lib/rules_inline/link.js

// Process [link](<to> "stuff")

'use strict';

var parseLinkLabel       = require('../helpers/parse_link_label');
var parseLinkDestination = require('../helpers/parse_link_destination');
var parseLinkTitle       = require('../helpers/parse_link_title');
var normalizeReference   = require('../helpers/normalize_reference');


module.exports = function link(state, silent) {
  var code,
      href,
      label,
      labelEnd,
      labelStart,
      pos,
      res,
      ref,
      title,
      oldPos = state.pos,
      max = state.posMax,
      start = state.pos;

  if (state.src.charCodeAt(state.pos) !== 0x5B/* [ */) { return false; }

  labelStart = state.pos + 1;
  labelEnd = parseLinkLabel(state, state.pos, true);

  // parser failed to find ']', so it's not a valid link
  if (labelEnd < 0) { return false; }

  pos = labelEnd + 1;
  if (pos < max && state.src.charCodeAt(pos) === 0x28/* ( */) {
    //
    // Inline link
    //

    // [link](  <href>  "title"  )
    //        ^^ skipping these spaces
    pos++;
    for (; pos < max; pos++) {
      code = state.src.charCodeAt(pos);
      if (code !== 0x20 && code !== 0x0A) { break; }
    }
    if (pos >= max) { return false; }

    // [link](  <href>  "title"  )
    //          ^^^^^^ parsing link destination
    start = pos;
    res = parseLinkDestination(state.src, pos, state.posMax);
    if (res.ok && state.md.inline.validateLink(res.str)) {
      href = res.str;
      pos = res.pos;
    } else {
      href = '';
    }

    // [link](  <href>  "title"  )
    //                ^^ skipping these spaces
    start = pos;
    for (; pos < max; pos++) {
      code = state.src.charCodeAt(pos);
      if (code !== 0x20 && code !== 0x0A) { break; }
    }

    // [link](  <href>  "title"  )
    //                  ^^^^^^^ parsing link title
    res = 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 (code !== 0x20 && code !== 0x0A) { break; }
      }
    } else {
      title = '';
    }

    if (pos >= max || state.src.charCodeAt(pos) !== 0x29/* ) */) {
      state.pos = oldPos;
      return false;
    }
    pos++;
  } else {
    //
    // Link reference
    //
    if (typeof state.env.references === 'undefined') { return false; }

    // [foo]  [bar]
    //      ^^ optional whitespace (can include newlines)
    for (; pos < max; pos++) {
      code = state.src.charCodeAt(pos);
      if (code !== 0x20 && code !== 0x0A) { break; }
    }

    if (pos < max && state.src.charCodeAt(pos) === 0x5B/* [ */) {
      start = pos + 1;
      pos = 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;

    state.push({
      type: 'link_open',
      href: href,
      target: '',
      title: title,
      level: state.level++
    });
    state.md.inline.tokenize(state);
    state.push({ type: 'link_close', level: --state.level });
  }

  state.pos = pos;
  state.posMax = max;
  return true;
};