Fix edge case for list indents

Now list items cannot be indented more than 4 spaces from the first,
as per commonmark 0.29 spec:
 - item 1
  - item 2
   - item 3
    - item 4
     - this one is a paragraph continuation

lib/rules_block/list.js

@@ -114,9 +114,9 @@ module.exports = function list(state, startLine, endLine, silent) {
       max,
       nextLine,
       offset,
-      oldIndent,
-      oldLIndent,
+      oldListIndent,
       oldParentType,
+      oldSCount,
       oldTShift,
       oldTight,
       pos,
@@ -132,6 +132,18 @@ module.exports = function list(state, startLine, endLine, silent) {
   // if it's indented more than 3 spaces, it should be a code block
   if (state.sCount[startLine] - state.blkIndent >= 4) { return false; }
 
+  // Special case:
+  //  - item 1
+  //   - item 2
+  //    - item 3
+  //     - item 4
+  //      - this one is a paragraph continuation
+  if (state.listIndent >= 0 &&
+      state.sCount[startLine] - state.listIndent >= 4 &&
+      state.sCount[startLine] < state.blkIndent) {
+    return false;
+  }
+
   // limit conditions when list can interrupt
   // a paragraph (validation mode only)
   if (silent && state.parentType === 'paragraph') {
@@ -243,11 +255,19 @@ module.exports = function list(state, startLine, endLine, silent) {
     token.markup = String.fromCharCode(markerCharCode);
     token.map    = itemLines = [ startLine, 0 ];
 
-    oldIndent = state.blkIndent;
+    // change current state, then restore it after parser subcall
     oldTight = state.tight;
     oldTShift = state.tShift[startLine];
-    oldLIndent = state.sCount[startLine];
+    oldSCount = state.sCount[startLine];
+
+    //  - example list
+    // ^ listIndent position will be here
+    //   ^ blkIndent position will be here
+    //
+    oldListIndent = state.listIndent;
+    state.listIndent = state.blkIndent;
     state.blkIndent = indent;
+
     state.tight = true;
     state.tShift[startLine] = contentStart - state.bMarks[startLine];
     state.sCount[startLine] = offset;
@@ -273,9 +293,10 @@ module.exports = function list(state, startLine, endLine, silent) {
     // but we should filter last element, because it means list finish
     prevEmptyEnd = (state.line - startLine) > 1 && state.isEmpty(state.line - 1);
 
-    state.blkIndent = oldIndent;
+    state.blkIndent = state.listIndent;
+    state.listIndent = oldListIndent;
     state.tShift[startLine] = oldTShift;
-    state.sCount[startLine] = oldLIndent;
+    state.sCount[startLine] = oldSCount;
     state.tight = oldTight;
 
     token        = state.push('list_item_close', 'li', -1);
@@ -292,6 +313,9 @@ module.exports = function list(state, startLine, endLine, silent) {
     //
     if (state.sCount[nextLine] < state.blkIndent) { break; }
 
+    // if it's indented more than 3 spaces, it should be a code block
+    if (state.sCount[startLine] - state.blkIndent >= 4) { break; }
+
     // fail if terminating block found
     terminate = false;
     for (i = 0, l = terminatorRules.length; i < l; i++) {

lib/rules_block/state_block.js

@@ -40,12 +40,13 @@ function StateBlock(src, md, env, tokens) {
   this.bsCount = [];
 
   // block parser variables
-  this.blkIndent  = 0; // required block content indent
-                       // (for example, if we are in list)
+  this.blkIndent  = 0; // required block content indent (for example, if we are
+                       // inside a list, it would be positioned after list marker)
   this.line       = 0; // line index in src
   this.lineMax    = 0; // lines count
   this.tight      = false;  // loose/tight mode for lists
   this.ddIndent   = -1; // indent of the current dd block (-1 if there isn't any)
+  this.listIndent = -1; // indent of the current list block (-1 if there isn't any)
 
   // can be 'blockquote', 'list', 'root', 'paragraph' or 'reference'
   // used in lists to determine if they interrupt a paragraph

test/fixtures/commonmark/bad.txt

@@ -1,67 +0,0 @@
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-src line: 5176
-
-.
-- a
- - b
-  - c
-   - d
-    - e
-.
-<ul>
-<li>a</li>
-<li>b</li>
-<li>c</li>
-<li>d
-- e</li>
-</ul>
-.
-
-error:
-
-<ul>
-<li>a</li>
-<li>b</li>
-<li>c</li>
-<li>d</li>
-<li>e</li>
-</ul>
-
-
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-src line: 5196
-
-.
-1. a
-
-  2. b
-
-    3. c
-.
-<ol>
-<li>
-<p>a</p>
-</li>
-<li>
-<p>b</p>
-</li>
-</ol>
-<pre><code>3. c
-</code></pre>
-.
-
-error:
-
-<ol>
-<li>
-<p>a</p>
-</li>
-<li>
-<p>b</p>
-</li>
-<li>
-<p>c</p>
-</li>
-</ol>
-
-

test/fixtures/commonmark/good.txt

@@ -4027,6 +4027,47 @@ src line: 5152
 </ol>
 .
 
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+src line: 5176
+
+.
+- a
+ - b
+  - c
+   - d
+    - e
+.
+<ul>
+<li>a</li>
+<li>b</li>
+<li>c</li>
+<li>d
+- e</li>
+</ul>
+.
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+src line: 5196
+
+.
+1. a
+
+  2. b
+
+    3. c
+.
+<ol>
+<li>
+<p>a</p>
+</li>
+<li>
+<p>b</p>
+</li>
+</ol>
+<pre><code>3. c
+</code></pre>
+.
+
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 src line: 5219