Parse link reference definitions

lib/lexer_block.js

@@ -163,7 +163,7 @@ LexerBlock.prototype.tokenize = function (state, startLine, endLine) {
 };
 
 
-LexerBlock.prototype.parse = function (src, options) {
+LexerBlock.prototype.parse = function (src, options, env) {
   var state, lineStart = 0, lastTabPos = 0;
 
   if (!src) { return ''; }
@@ -201,7 +201,8 @@ LexerBlock.prototype.parse = function (src, options) {
     src,
     this,
     [],
-    options
+    options,
+    env
   );
 
   this.tokenize(state, state.line, state.lineMax);

lib/lexer_block/paragraph.js

@@ -8,7 +8,7 @@ var getLines = require('../helpers').getLines;
 
 
 module.exports = function paragraph(state, startLine/*, endLine*/) {
-  var endLine,
+  var endLine, content, ref, t,
       nextLine = startLine + 1,
       rules_named = state.lexer.rules_named;
 
@@ -34,12 +34,22 @@ module.exports = function paragraph(state, startLine/*, endLine*/) {
     //if (rules_named.def(state, nextLine, endLine, true)) { break; }
   }
 
+  content = getLines(state, startLine, nextLine, state.blkIndent, false).trim();
+
+  while ((ref = state.lexer.inline.parse_reference(content, state.options, state.env))) {
+    t = state.env.references;
+    t[ref.label] = t[ref.label] || { title: ref.title, href: ref.href };
+    content = ref.remaining;
+  }
+
+  if (content) {
     state.tokens.push({ type: 'paragraph_open' });
     state.tokens.push({
       type: 'inline',
-    content: getLines(state, startLine, nextLine, state.blkIndent, false).trim()
+      content: content
     });
     state.tokens.push({ type: 'paragraph_close' });
+  }
 
   state.line = nextLine;
   return true;

lib/lexer_block/state_block.js

@@ -3,7 +3,7 @@
 'use strict';
 
 
-function State(src, lexer, tokens, options) {
+function State(src, lexer, tokens, options, env) {
   var ch, s, start, pos, len, indent, indent_found;
 
   // TODO: check if we can move string replaces to parser, to avoid
@@ -23,6 +23,8 @@ function State(src, lexer, tokens, options) {
   // TODO: (?) set directly for faster access.
   this.options = options;
 
+  this.env = env;
+
   //
   // Internal state vartiables
   //

lib/lexer_inline.js

@@ -4,6 +4,8 @@
 
 
 var StateInline = require('./lexer_inline/state_inline');
+var links = require('./lexer_inline/links');
+var skipSpaces = require('./helpers').skipSpaces;
 
 ////////////////////////////////////////////////////////////////////////////////
 // Lexer rules
@@ -154,13 +156,68 @@ LexerInline.prototype.tokenize = function (state) {
 
 // Parse input string.
 //
-LexerInline.prototype.parse = function (str, options) {
+LexerInline.prototype.parse = function (str, options, env) {
-  var state = new StateInline(str, this, options);
+  var state = new StateInline(str, this, options, env);
 
   this.tokenize(state);
 
   return state.tokens;
 };
 
+// Parse link reference definition.
+//
+LexerInline.prototype.parse_reference = function (str, options) {
+  var state, labelEnd, pos, max, code, start, href, title;
+
+  if (str.charCodeAt(0) !== 0x5B/* [ */) { return null; }
+
+  state = new StateInline(str, this, options);
+  labelEnd = links.parseLinkLabel(state, 0);
+
+  if (labelEnd < 0 || str.charCodeAt(labelEnd + 1) !== 0x3A/* : */) { return null; }
+
+  max = state.posMax;
+
+  // [label]:   destination   'title'
+  //         ^^^ skip optional whitespace here
+  for (pos = labelEnd + 2; pos < max; pos++) {
+    code = state.src.charCodeAt(pos);
+    if (code !== 0x20 && code !== 0x0A) { break; }
+  }
+
+  // [label]:   destination   'title'
+  //            ^^^^^^^^^^^ parse this
+  href = links.parseLinkDestination(state, pos);
+  if (href === null) { return null; }
+  pos = state.pos;
+
+  // [label]:   destination   'title'
+  //                       ^^^ skipping those spaces
+  start = pos;
+  for (pos = pos + 1; pos < max; pos++) {
+    code = state.src.charCodeAt(pos);
+    if (code !== 0x20 && code !== 0x0A) { break; }
+  }
+
+  // [label]:   destination   'title'
+  //                          ^^^^^^^ parse this
+  if (pos < max && start !== pos && (title = links.parseLinkTitle(state, pos)) !== null) {
+    pos = state.pos;
+  } else {
+    title = '';
+  }
+
+  // ensure that the end of the line is empty
+  pos = skipSpaces(state, pos);
+  if (pos < max && state.src.charCodeAt(pos) !== 0x0A) { return null; }
+
+  return {
+    label: str.slice(1, labelEnd).trim().replace(/\s+/g, ' '),
+    title: title,
+    href: href,
+    remaining: str.slice(pos)
+  };
+};
+
 
 module.exports = LexerInline;

lib/lexer_inline/links.js

@@ -5,38 +5,17 @@
 
 var skipSpaces = require('../helpers').skipSpaces;
 
-
-module.exports = function links(state) {
-  var oldLength,
-      oldPending,
-      level,
-      rules,
-      len,
-      i,
-      ok,
-      found,
-      labelStart,
-      labelEnd,
-      href,
-      title,
-      pos,
-      code,
-      isImage = false,
-      max = state.posMax,
-      start = state.pos,
-      marker = state.src.charCodeAt(start);
-
-  if (marker === 0x21/* ! */) {
-    isImage = true;
-    marker = state.src.charCodeAt(++start);
-  }
-
-  if (marker !== 0x5B/* [ */) { return false; }
-
 //
 // Parse link label
 //
-  oldLength = state.tokens.length;
+// this function assumes that first character ("[") already matches;
+// returns the end of the label
+function parseLinkLabel(state, start) {
+  var level, rules, len, found, marker, i, ok,
+      labelEnd = -1,
+      max = state.posMax,
+      oldPos = state.pos,
+      oldLength = state.tokens.length,
       oldPending = state.pending;
 
   state.pos = start + 1;
@@ -60,7 +39,7 @@ module.exports = function links(state) {
       // skip emphasis because it has lower priority, compare:
       //  [foo *bar]()*
       //  [foo `bar]()`
-      if (rules[i].name !== 'emphasis' && rules[i] !== links) {
+      if (rules[i].name !== 'emphasis' && rules[i].name !== 'links') {
         ok = rules[i](state);
       }
       if (ok) { break; }
@@ -69,38 +48,34 @@ module.exports = function links(state) {
     if (!ok) { state.pending += state.src[state.pos++]; }
   }
 
+  if (found) { labelEnd = state.pos; }
+
   // restore old state
-  labelStart = start + 1;
+  state.pos = oldPos;
-  labelEnd = state.pos;
-  state.pos = start;
   state.tokens.length = oldLength;
   state.pending = oldPending;
 
-  // parser failed to find ']', so it's not a valid link
+  return labelEnd;
-  if (!found) { return false; }
+}
 
 //
-  // Parse link destination and title
+// Parse link destination
 //
-  pos = labelEnd + 1;
+// on success it returns a string and updates state.pos;
-  href = title = '';
+// on failure it returns null
-  if (pos >= max || state.src.charCodeAt(pos) !== 0x28/* ( */) { return false; }
+function parseLinkDestination(state, pos) {
-
+  var code, level,
-  // [link](  <href>  "title"  )
+      max = state.posMax,
-  //        ^^ skipping these spaces
+      href = '';
-  pos++;
-  if ((pos = skipSpaces(state, pos)) >= max) { return false; }
 
-  // [link](  <href>  "title"  )
-  //          ^^^^^^ parsing link destination
   if (state.src.charCodeAt(pos) === 0x3C /* < */) {
     pos++;
     while (pos < max) {
       code = state.src.charCodeAt(pos);
-      if (code === 0x0A /* \n */) { return false; }
+      if (code === 0x0A /* \n */) { return null; }
       if (code === 0x3E /* > */) {
-        pos++;
+        state.pos = pos + 1;
-        break;
+        return href;
       }
       if (code === 0x5C /* \ */) {
         pos++;
@@ -110,7 +85,13 @@ module.exports = function links(state) {
 
       href += state.src[pos++];
     }
-  } else {
+
+    // no closing '>'
+    return null;
+  }
+
+  // this should be ... } else { ... branch
+
   level = 0;
   while (pos < max) {
     code = state.src.charCodeAt(pos);
@@ -118,7 +99,7 @@ module.exports = function links(state) {
     if (code === 0x20) { break; }
 
     // ascii control characters
-      if (code < 0x20 || code === 0x7F) { return false; }
+    if (code < 0x20 || code === 0x7F) { return null; }
 
     if (code === 0x5C /* \ */) {
       pos++;
@@ -128,7 +109,7 @@ module.exports = function links(state) {
 
     if (code === 0x28 /* ( */) {
       level++;
-        if (level > 1) { return false; }
+      if (level > 1) { return null; }
     }
 
     if (code === 0x29 /* ) */) {
@@ -140,19 +121,27 @@ module.exports = function links(state) {
 
     href += state.src[pos++];
   }
-  }
 
-  // [link](  <href>  "title"  )
+  if (!href.length) { return null; }
-  //                ^^ skipping these spaces
-  start = pos;
-  if ((pos = skipSpaces(state, pos)) >= max) { return false; }
 
-  // [link](  <href>  "title"  )
+  state.pos = pos;
-  //                  ^^^^^^^ parsing link title
+  return href;
+}
+
+//
+// Parse link title
+//
+// on success it returns a string and updates state.pos;
+// on failure it returns null
+function parseLinkTitle(state, pos) {
+  var title, code,
+      max = state.posMax,
       marker = state.src.charCodeAt(pos);
-  if (start !== pos) {
+
-    if (marker === 0x22 /* " */ || marker === 0x27 /* ' */ || marker === 0x28 /* ( */) {
+  if (marker !== 0x22 /* " */ && marker !== 0x27 /* ' */ && marker !== 0x28 /* ( */) { return null; }
+
   pos++;
+  title = '';
 
   // if opening marker is "(", switch it to closing marker ")"
   if (marker === 0x28) { marker = 0x29; }
@@ -160,8 +149,8 @@ module.exports = function links(state) {
   while (pos < max) {
     code = state.src.charCodeAt(pos);
     if (code === marker) {
-          pos++;
+      state.pos = pos + 1;
-          break;
+      return title;
     }
     if (code === 0x5C /* \ */) {
       pos++;
@@ -171,13 +160,86 @@ module.exports = function links(state) {
 
     title += state.src[pos++];
   }
+
+  return null;
 }
+
+function links(state) {
+  var labelStart,
+      labelEnd,
+      href,
+      title,
+      pos,
+      ref,
+      isImage = false,
+      max = state.posMax,
+      start = state.pos,
+      marker = state.src.charCodeAt(start);
+
+  if (marker === 0x21/* ! */) {
+    isImage = true;
+    marker = state.src.charCodeAt(++start);
   }
 
+  if (marker !== 0x5B/* [ */) { return false; }
+
+  labelStart = start + 1;
+  labelEnd = parseLinkLabel(state, start);
+
+  // parser failed to find ']', so it's not a valid link
+  if (pos < 0) { return false; }
+
+  pos = labelEnd + 1;
+  if (pos < max && state.src.charCodeAt(pos) === 0x28/* ( */) {
+    //
+    // Inline link
+    //
+
     // [link](  <href>  "title"  )
     //        ^^ skipping these spaces
+    pos++;
     if ((pos = skipSpaces(state, pos)) >= max) { return false; }
-  if (state.src.charCodeAt(pos) !== 0x29/* ) */) { return false; }
+
+    // [link](  <href>  "title"  )
+    //          ^^^^^^ parsing link destination
+    start = pos;
+    href = parseLinkDestination(state, pos);
+    if (href !== null) {
+      pos = state.pos;
+    } else {
+      href = '';
+    }
+
+    // [link](  <href>  "title"  )
+    //                ^^ skipping these spaces
+    start = pos;
+    pos = skipSpaces(state, pos);
+
+    // [link](  <href>  "title"  )
+    //                  ^^^^^^^ parsing link title
+    if (pos < max && start !== pos && (title = parseLinkTitle(state, pos)) !== null) {
+      pos = state.pos;
+
+      // [link](  <href>  "title"  )
+      //                         ^^ skipping these spaces
+      pos = skipSpaces(state, pos);
+    } else {
+      title = '';
+    }
+
+    if (pos >= max || state.src.charCodeAt(pos) !== 0x29/* ) */) {
+      state.pos = labelStart - 1;
+      return false;
+    }
+  } else {
+    //
+    // Link reference
+    //
+    ref = state.env.references[state.src.slice(labelStart, labelEnd).trim().replace(/\s+/g, ' ')];
+    if (!ref) { 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;
@@ -201,4 +263,9 @@ module.exports = function links(state) {
   state.pos = pos + 1;
   state.posMax = max;
   return true;
-};
+}
+
+module.exports = links;
+module.exports.parseLinkLabel = parseLinkLabel;
+module.exports.parseLinkDestination = parseLinkDestination;
+module.exports.parseLinkTitle = parseLinkTitle;

lib/lexer_inline/state_inline.js

@@ -3,8 +3,9 @@
 'use strict';
 
 
-function StateInline(src, lexer, options) {
+function StateInline(src, lexer, options, env) {
   this.src = src;
+  this.env = env;
   this.options = options;
   this.lexer = lexer;
   this.tokens = [];

lib/parser.js

@@ -21,6 +21,10 @@ function Parser(options) {
   this.block    = new LexerBlock();
   this.renderer = new Renderer();
 
+  // a bunch of cross-references between parsers
+  // used for link reference definitions
+  this.block.inline = this.inline;
+
   if (options) { this.set(options); }
 }
 
@@ -31,21 +35,21 @@ Parser.prototype.set = function (options) {
 
 
 Parser.prototype.render = function (src) {
-  var tokens, tok, i, l;
+  var tokens, tok, i, l, env = { references: Object.create(null) };
 
   // Parse blocks
-  tokens = this.block.parse(src, this.options);
+  tokens = this.block.parse(src, this.options, env);
 
   // Parse inlines
   for (i = 0, l = tokens.length; i < l; i++) {
     tok = tokens[i];
     if (tok.type === 'inline') {
-      tok.children = this.inline.parse(tok.content, this.options);
+      tok.children = this.inline.parse(tok.content, this.options, env);
     }
   }
 
   // Render
-  return this.renderer.render(tokens, this.options);
+  return this.renderer.render(tokens, this.options, env);
 };