Allow leading pipes to be ommitted

Author: nobu

lib/rdoc/markdown.kpeg

@@ -1198,17 +1198,22 @@ CodeFence = &{ github? }
             }
 
 Table = &{ github? }
-        TableRow:header TableLine:line TableRow+:body
+        TableHead:header TableLine:line TableRow+:body
         { table = RDoc::Markup::Table.new(header, line, body) }
 
-TableRow = TableItem+:row "|"? @Newline
-           { row }
-TableItem = "|" < (!"|" !@Newline .)+ >
+TableHead = TableItem2+:items "|"? @Newline
+            { items }
+
+TableRow = ( ( TableItem:item1 TableItem2*:items { [item1, *items] } ):row | TableItem2+:row ) "|"? @Newline
+	   { row }
+TableItem2 = "|" TableItem
+TableItem = < (!"|" !@Newline .)+ >
             { text.strip }
 
-TableLine = TableColumn+:line "|"? @Newline
-            { line }
-TableColumn = "|" < ( "-"+ ":"? | ":" "-"* ) >
+TableLine = ( ( TableAlign:align1 TableAlign2*:aligns {[align1, *aligns] } ):line | TableAlign2+:line ) "|"? @Newline
+	    { line }
+TableAlign2 = "|" TableAlign
+TableAlign = < /:?-+:?/ >
               { text.start_with?(":") ? :left :
                 text.end_with?(":") ? :right : nil
               }

test/rdoc/test_rdoc_markdown.rb

@@ -1065,9 +1065,9 @@ def test_gfm_table
   def test_gfm_table_2
     doc = parse <<~MD
     | Cmd | Returns | Meaning
-    |-----|---------|--------
-    | "b" | boolean | True if file1 is a block device
-    | "c" | boolean | True if file1 is a character device
+    ------|---------|--------
+    |"b"  | boolean | True if file1 is a block device
+    "c"   | boolean | True if file1 is a character device
     MD
 
     head = %w[Cmd Returns Meaning]