fix: #541

yuin · yuin · commit 2589b6a801c1 · 2026-01-06T02:32:05.000+09:00
diff --git a/_test/extra.txt b/_test/extra.txt
@@ -876,3 +876,10 @@ text" /></p>
 </li>
 </ul>
 //= = = = = = = = = = = = = = = = = = = = = = = =//
+
+70: Single letter ATX heading
+//- - - - - - - - -//
+# A
+//- - - - - - - - -//
+<h1>A</h1>
+//= = = = = = = = = = = = = = = = = = = = = = = =//
diff --git a/parser/atx_heading.go b/parser/atx_heading.go
@@ -126,14 +126,13 @@ func (b *atxHeadingParser) Open(parent ast.Node, reader text.Reader, pc Context)
 		i = stop - 1
 		for ; line[i] == '#' && i > 0; i-- {
 		}
-		if i == 0 { // empty headings like '### ###'
+		if i == 0 && line[0] == '#' { // empty headings like '### ###'
 			reader.AdvanceToEOL()
 			return node, NoChildren
 		}
-		if i == 0 || util.IsSpace(line[i]) {
+		if i != stop-1 && util.IsSpace(line[i]) {
 			stop = i
 			stop -= util.TrimRightSpaceLength(line[0:stop])
-
 		}
 	}
 	hl.Stop = hl.Start + stop

Original file line number	Diff line number	Diff line change
`@@ -126,14 +126,13 @@ func (b *atxHeadingParser) Open(parent ast.Node, reader text.Reader, pc Context)`
`126`	`126`	`i = stop - 1`
`127`	`127`	`for ; line[i] == '#' && i > 0; i-- {`
`128`	`128`	`}`
`129`		`- if i == 0 { // empty headings like '### ###'`
	`129`	`+ if i == 0 && line[0] == '#' { // empty headings like '### ###'`
`130`	`130`	`reader.AdvanceToEOL()`
`131`	`131`	`return node, NoChildren`
`132`	`132`	`}`
`133`		`- if i == 0 \|\| util.IsSpace(line[i]) {`
	`133`	`+ if i != stop-1 && util.IsSpace(line[i]) {`
`134`	`134`	`stop = i`
`135`	`135`	`stop -= util.TrimRightSpaceLength(line[0:stop])`
`136`		`-`
`137`	`136`	`}`
`138`	`137`	`}`
`139`	`138`	`hl.Stop = hl.Start + stop`