fix: Full Commonmark compliance for Lists

src/Lexer.js

@@ -153,7 +153,7 @@ module.exports = class Lexer {
         src = src.substring(token.raw.length);
         lastToken = tokens[tokens.length - 1];
         // An indented code block cannot interrupt a paragraph.
-        if (lastToken && lastToken.type === 'paragraph') {
+        if (lastToken && (lastToken.type === 'paragraph' || lastToken.type === 'text')) {
           lastToken.raw += '\n' + token.raw;
           lastToken.text += '\n' + token.text;
         } else {
@@ -204,6 +204,10 @@ module.exports = class Lexer {
         l = token.items.length;
         for (i = 0; i < l; i++) {
           token.items[i].tokens = this.blockTokens(token.items[i].text, [], false);
+          if (token.items[i].tokens.some(t => t.type === 'space')) {
+            token.loose = true;
+            token.items[i].loose = true;
+          }
         }
         tokens.push(token);
         continue;
@@ -217,13 +221,19 @@ module.exports = class Lexer {
       }
 
       // def
-      if (top && (token = this.tokenizer.def(src))) {
+      if (token = this.tokenizer.def(src)) {
         src = src.substring(token.raw.length);
-        if (!this.tokens.links[token.tag]) {
-          this.tokens.links[token.tag] = {
-            href: token.href,
-            title: token.title
-          };
+        lastToken = tokens[tokens.length - 1];
+        if (lastToken && (lastToken.type === 'paragraph' || lastToken.type === 'text')) {
+          lastToken.raw += '\n' + token.raw;
+          lastToken.text += '\n' + token.raw;
+        } else {
+          if (!this.tokens.links[token.tag]) {
+            this.tokens.links[token.tag] = {
+              href: token.href,
+              title: token.title
+            };
+          }
         }
         continue;
       }

src/Parser.js

@@ -149,7 +149,7 @@ module.exports = class Parser {
             if (item.task) {
               checkbox = this.renderer.checkbox(checked);
               if (loose) {
-                if (item.tokens.length > 0 && item.tokens[0].type === 'text') {
+                if (item.tokens.length > 0 && item.tokens[0].type === 'paragraph') {
                   item.tokens[0].text = checkbox + ' ' + item.tokens[0].text;
                   if (item.tokens[0].tokens && item.tokens[0].tokens.length > 0 && item.tokens[0].tokens[0].type === 'text') {
                     item.tokens[0].tokens[0].text = checkbox + ' ' + item.tokens[0].tokens[0].text;

src/Tokenizer.js

@@ -194,134 +194,138 @@ module.exports = class Tokenizer {
   }
 
   list(src) {
-    const cap = this.rules.block.list.exec(src);
+    let cap = this.rules.block.list.exec(src);
     if (cap) {
-      let raw = cap[0];
-      const bull = cap[2];
+      let raw, istask, ischecked, indent, i, blankLine, endsWithBlankLine,
+        line, lines, itemContents;
+
+      let bull = cap[1].trim();
       const isordered = bull.length > 1;
 
       const list = {
         type: 'list',
-        raw,
+        raw: '',
         ordered: isordered,
         start: isordered ? +bull.slice(0, -1) : '',
         loose: false,
         items: []
       };
 
-      // Get each top-level item.
-      const itemMatch = cap[0].match(this.rules.block.item);
-
-      let next = false,
-        item,
-        space,
-        bcurr,
-        bnext,
-        addBack,
-        loose,
-        istask,
-        ischecked,
-        endMatch;
-
-      let l = itemMatch.length;
-      bcurr = this.rules.block.listItemStart.exec(itemMatch[0]);
-      for (let i = 0; i < l; i++) {
-        item = itemMatch[i];
-        raw = item;
-
-        if (!this.options.pedantic) {
-          // Determine if current item contains the end of the list
-          endMatch = item.match(new RegExp('\\n\\s*\\n {0,' + (bcurr[0].length - 1) + '}\\S'));
-          if (endMatch) {
-            addBack = item.length - endMatch.index + itemMatch.slice(i + 1).join('\n').length;
-            list.raw = list.raw.substring(0, list.raw.length - addBack);
-
-            item = item.substring(0, endMatch.index);
-            raw = item;
-            l = i + 1;
-          }
+      bull = isordered ? `\\d{1,9}\\${bull.slice(-1)}` : `\\${bull}`;
+
+      if (this.options.pedantic) {
+        bull = isordered ? bull : '[*+-]';
+      }
+
+      // Get next list item
+      const itemRegex = new RegExp(`^( {0,3}${bull})((?: [^\\n]*| *)(?:\\n[^\\n]*)*(?:\\n|$))`);
+
+      // Get each top-level item
+      while (src) {
+        if (this.rules.block.hr.test(src)) { // End list if we encounter an HR (possibly move into itemRegex?)
+          break;
         }
 
-        // Determine whether the next list item belongs here.
-        // Backpedal if it does not belong in this list.
-        if (i !== l - 1) {
-          bnext = this.rules.block.listItemStart.exec(itemMatch[i + 1]);
-          if (
-            !this.options.pedantic
-              ? bnext[1].length >= bcurr[0].length || bnext[1].length > 3
-              : bnext[1].length > bcurr[1].length
-          ) {
-            // nested list or continuation
-            itemMatch.splice(i, 2, itemMatch[i] + (!this.options.pedantic && bnext[1].length < bcurr[0].length && !itemMatch[i].match(/\n$/) ? '' : '\n') + itemMatch[i + 1]);
-            i--;
-            l--;
-            continue;
-          } else if (
-            // different bullet style
-            !this.options.pedantic || this.options.smartLists
-              ? bnext[2][bnext[2].length - 1] !== bull[bull.length - 1]
-              : isordered === (bnext[2].length === 1)
-          ) {
-            addBack = itemMatch.slice(i + 1).join('\n').length;
-            list.raw = list.raw.substring(0, list.raw.length - addBack);
-            i = l - 1;
-          }
-          bcurr = bnext;
+        if (!(cap = itemRegex.exec(src))) {
+          break;
         }
 
-        // Remove the list item's bullet
-        // so it is seen as the next token.
-        space = item.length;
-        item = item.replace(/^ *([*+-]|\d+[.)]) ?/, '');
-
-        // Outdent whatever the
-        // list item contains. Hacky.
-        if (~item.indexOf('\n ')) {
-          space -= item.length;
-          item = !this.options.pedantic
-            ? item.replace(new RegExp('^ {1,' + space + '}', 'gm'), '')
-            : item.replace(/^ {1,4}/gm, '');
+        lines = cap[2].split('\n');
+
+        if (this.options.pedantic) {
+          indent = 2;
+          itemContents = lines[0].trimLeft();
+        } else {
+          indent = cap[2].search(/[^ ]/); // Find first non-space char
+          indent = cap[1].length + (indent > 4 ? 1 : indent); // intented code blocks after 4 spaces; indent is always 1
+          itemContents = lines[0].slice(indent - cap[1].length);
         }
 
-        // trim item newlines at end
-        item = rtrim(item, '\n');
-        if (i !== l - 1) {
-          raw = raw + '\n';
+        blankLine = false;
+        raw = cap[0];
+
+        if (!lines[0] && /^ *$/.test(lines[1])) { // items begin with at most one blank line
+          raw = cap[1] + lines.slice(0, 2).join('\n') + '\n';
+          list.loose = true;
+          lines = [];
         }
 
-        // Determine whether item is loose or not.
-        // Use: /(^|\n)(?! )[^\n]+\n\n(?!\s*$)/
-        // for discount behavior.
-        loose = next || /\n\n(?!\s*$)/.test(raw);
-        if (i !== l - 1) {
-          next = raw.slice(-2) === '\n\n';
-          if (!loose) loose = next;
+        const nextBulletRegex = new RegExp(`^ {0,${Math.min(3, indent - 1)}}(?:[*+-]|\\d{1,9}[.)])`);
+
+        for (i = 1; i < lines.length; i++) {
+          line = lines[i];
+
+          if (this.options.pedantic) { // Re-align to follow commonmark nesting rules
+            line = line.replace(/^ {1,4}(?=( {4})*[^ ])/g, '  ');
+          }
+
+          // End list item if found start of new bullet
+          if (nextBulletRegex.test(line)) {
+            raw = cap[1] + lines.slice(0, i).join('\n') + '\n';
+            break;
+          }
+
+          // Until we encounter a blank line, item contents do not need indentation
+          if (!blankLine) {
+            if (!line.trim()) { // Check if current line is empty
+              blankLine = true;
+            }
+
+            // Dedent if possible
+            if (line.search(/[^ ]/) >= indent) {
+              itemContents += '\n' + line.slice(indent);
+            } else {
+              itemContents += '\n' + line;
+            }
+            continue;
+          }
+
+          // Dedent this line
+          if (line.search(/[^ ]/) >= indent || !line.trim()) {
+            itemContents += '\n' + line.slice(indent);
+            continue;
+          } else { // Line was not properly indented; end of this item
+            raw = cap[1] + lines.slice(0, i).join('\n') + '\n';
+            break;
+          }
         }
 
-        if (loose) {
-          list.loose = true;
+        if (!list.loose) {
+          // If the previous item ended with a blank line, the list is loose
+          if (endsWithBlankLine) {
+            list.loose = true;
+          } else if (/\n *\n *$/.test(raw)) {
+            endsWithBlankLine = true;
+          }
         }
 
         // Check for task list items
         if (this.options.gfm) {
-          istask = /^\[[ xX]\] /.test(item);
-          ischecked = undefined;
+          istask = /^\[[ xX]\] /.exec(itemContents);
           if (istask) {
-            ischecked = item[1] !== ' ';
-            item = item.replace(/^\[[ xX]\] +/, '');
+            ischecked = istask[0] !== '[ ] ';
+            itemContents = itemContents.replace(/^\[[ xX]\] +/, '');
           }
         }
 
         list.items.push({
           type: 'list_item',
-          raw,
-          task: istask,
+          raw: raw,
+          task: !!istask,
           checked: ischecked,
-          loose: loose,
-          text: item
+          loose: false,
+          text: itemContents
         });
+
+        list.raw += raw;
+        src = src.slice(raw.length);
       }
 
+      // Do not consume ending newlines. Alternatively, make itemRegex *start* with any newlines to simplify/speed up endsWithBlankLine logic
+      list.items[list.items.length - 1].raw = raw.trimRight();
+      list.items[list.items.length - 1].text = itemContents.trimRight();
+      list.raw = list.raw.trimRight();
+
       return list;
     }
   }

src/rules.js

@@ -10,11 +10,11 @@ const {
 const block = {
   newline: /^(?: *(?:\n|$))+/,
   code: /^( {4}[^\n]+(?:\n(?: *(?:\n|$))*)?)+/,
-  fences: /^ {0,3}(`{3,}(?=[^`\n]*\n)|~{3,})([^\n]*)\n(?:|([\s\S]*?)\n)(?: {0,3}\1[~`]* *(?:\n+|$)|$)/,
+  fences: /^ {0,3}(`{3,}(?=[^`\n]*\n)|~{3,})([^\n]*)\n(?:|([\s\S]*?)\n)(?: {0,3}\1[~`]* *(?=\n|$)|$)/,
   hr: /^ {0,3}((?:- *){3,}|(?:_ *){3,}|(?:\* *){3,})(?:\n+|$)/,
   heading: /^ {0,3}(#{1,6})(?=\s|$)(.*)(?:\n+|$)/,
   blockquote: /^( {0,3}> ?(paragraph|[^\n]*)(?:\n|$))+/,
-  list: /^( {0,3})(bull) [\s\S]+?(?:hr|def|\n{2,}(?! )(?! {0,3}bull )\n*|\s*$)/,
+  list: /^( {0,3}bull)( [^\n]+?)?(?:\n|$)/,
   html: '^ {0,3}(?:' // optional indentation
     + '<(script|pre|style|textarea)[\\s>][\\s\\S]*?(?:</\\1>[^\\n]*\\n+|$)' // (1)
     + '|comment[^\\n]*(\\n+|$)' // (2)
@@ -43,11 +43,6 @@ block.def = edit(block.def)
   .getRegex();
 
 block.bullet = /(?:[*+-]|\d{1,9}[.)])/;
-block.item = /^( *)(bull) ?[^\n]*(?:\n(?! *bull ?)[^\n]*)*/;
-block.item = edit(block.item, 'gm')
-  .replace(/bull/g, block.bullet)
-  .getRegex();
-
 block.listItemStart = edit(/^( *)(bull) */)
   .replace('bull', block.bullet)
   .getRegex();