support tables with missing values

(and add supporting test case)

lib/rules_block/table.js

@@ -143,9 +143,12 @@ module.exports = function table(state, startLine, endLine, silent) {
   for (nextLine = startLine + 2; nextLine < endLine; nextLine++) {
     if (state.sCount[nextLine] < state.blkIndent) { break; }
 
-    lineText = getLine(state, nextLine).trim();
+    lineText = getLine(state, nextLine);
     if (lineText.indexOf('|') === -1) { break; }
-    columns = escapedSplit(lineText.replace(/^\||\|$/g, ''));
+
+    // keep spaces at beginning of line to indicate an empty first cell, but
+    // strip trailing whitespace
+    columns = escapedSplit(lineText.replace(/^\||\|\s*$/g, ''));
 
     token = state.push('tr_open', 'tr', 1);
     for (i = 0; i < columnCount; i++) {

test/fixtures/markdown-it/tables.txt

@@ -470,3 +470,35 @@ Allow one-column tables (issue #171):
 </tbody>
 </table>
 .
+
+
+Allow tables with missing values:
+.
+0,0 | 0,1 | 0,2
+--- | --- | ---
+1,0 |     | 1,2
+    | 2,1 |
+
+.
+<table>
+<thead>
+<tr>
+<th>0,0</th>
+<th>0,1</th>
+<th>0,2</th>
+</tr>
+</thead>
+<tbody>
+<tr>
+<td>1,0</td>
+<td></td>
+<td>1,2</td>
+</tr>
+<tr>
+<td></td>
+<td>2,1</td>
+<td></td>
+</tr>
+</tbody>
+</table>
+.