Only check for TOML block at the start

When we already outputted something, stop checking for the TOML block.
We take special care to check if the header is outputted already,
because that is the *only* element that does not need syntax to be
outputted.

block.go

@@ -85,9 +85,11 @@ func (p *parser) block(out *bytes.Buffer, data []byte) {
 		if p.flags&EXTENSION_TITLEBLOCK_TOML != 0 && len(data) > 2 {
 			// only one % at the left
 			if data[0] == '%' && data[1] != '%' {
-				if i := p.titleBlock(out, data, true); i > 0 {
-					data = data[i:]
-					continue
+				if out.Len() <= p.headerLen {
+					if i := p.titleBlock(out, data, true); i > 0 {
+						data = data[i:]
+						continue
+					}
 				}
 			}
 		}
@@ -99,11 +101,12 @@ func (p *parser) block(out *bytes.Buffer, data []byte) {
 		// %%%
 		if p.flags&EXTENSION_TITLEBLOCK_TOML != 0 && len(data) > 3 {
 			if data[0] == '%' && data[1] == '%' && data[2] == '%' {
-				if i := p.titleBlockBlock(out, data, true); i > 0 {
-					data = data[i:]
-					continue
+				if out.Len() <= p.headerLen {
+					if i := p.titleBlockBlock(out, data, true); i > 0 {
+						data = data[i:]
+						continue
+					}
 				}
-
 			}
 		}
 

markdown.go

@@ -283,6 +283,7 @@ type parser struct {
 
 	appendix   bool // have we seen a {backmatter}?
 	titleblock bool // have we seen a titleblock
+	headerLen  int  // if a header is written what is length
 
 	partCount    int // TODO, keep track of part counts (-#)
 	chapterCount int // TODO, keep track of chapter count (#)
@@ -468,6 +469,7 @@ func secondPass(p *parser, input []byte, depth int) *bytes.Buffer {
 	var output bytes.Buffer
 
 	p.r.DocumentHeader(&output, depth == 0)
+	p.headerLen = output.Len()
 	p.block(&output, input)
 
 	if p.flags&EXTENSION_FOOTNOTES != 0 && len(p.notes) > 0 {