all: detach parsing preamble from content

This is to prevent empty preamble being rendered in HTML content.

8 files changed, 57 insertions, 47 deletions

diff --git a/asciidoctor.go b/asciidoctor.go
index c6888ac..12942c0 100644
--- a/asciidoctor.go
+++ b/asciidoctor.go
@@ -12,6 +12,8 @@ import "github.com/shuLhan/share/lib/math/big"
 const (
 	// Version of this module.
 	Version = `0.3.3-dev`
+
+	_lf = "\n"
 )
 
 func init() {
diff --git a/document.go b/document.go
index 653a3e1..2b1cd91 100644
--- a/document.go
+++ b/document.go
@@ -85,19 +85,10 @@ func newDocument() (doc *Document) {
 		header: &element{
 			kind: elKindDocHeader,
 		},
-		preamble: &element{
-			elementAttribute: elementAttribute{
-				Attrs: make(map[string]string),
-			},
-			kind: elKindPreamble,
-		},
 		content: &element{
 			kind: elKindDocContent,
 		},
 	}
-
-	doc.content.addChild(doc.preamble)
-
 	return doc
 }
 
@@ -157,7 +148,16 @@ func parse(doc *Document, content []byte) {
 		doc.sectLevel, _ = strconv.Atoi(sectLevel)
 	}
 
-	docp.parseBlock(doc.preamble, 0)
+	if docp.hasPreamble() {
+		doc.preamble = &element{
+			elementAttribute: elementAttribute{
+				Attrs: make(map[string]string),
+			},
+			kind: elKindPreamble,
+		}
+		docp.parseBlock(doc.preamble, 0)
+	}
+	docp.parseBlock(doc.content, 0)
 }
 
 // ToHTMLEmbedded convert the Document object into HTML with content only,
diff --git a/document_parser.go b/document_parser.go
index 2a29152..45b7597 100644
--- a/document_parser.go
+++ b/document_parser.go
@@ -118,6 +118,27 @@ func (docp *documentParser) consumeLinesUntil(el *element, term int, terms []int
 	return line
 }
 
+// hasPreamble will return true if the contents contains preamble, indicated
+// by the first section that found after current line.
+func (docp *documentParser) hasPreamble() bool {
+	var (
+		start = docp.lineNum
+
+		line []byte
+		kind int
+	)
+	for ; start < len(docp.lines); start++ {
+		line = docp.lines[start]
+		kind, _, _ = whatKindOfLine(line)
+		if kind == elKindSectionL1 || kind == elKindSectionL2 ||
+			kind == elKindSectionL3 || kind == elKindSectionL4 ||
+			kind == elKindSectionL5 {
+			return true
+		}
+	}
+	return false
+}
+
 func (docp *documentParser) include(el *elementInclude) {
 	var (
 		content []byte = bytes.ReplaceAll(el.content, []byte("\r\n"), []byte("\n"))
@@ -336,9 +357,15 @@ func (docp *documentParser) parseBlock(parent *element, term int) {
 			el = new(element)
 			continue
 
-		case elKindSectionL1, elKindSectionL2,
-			elKindSectionL3, elKindSectionL4,
-			elKindSectionL5:
+		case elKindSectionL1, elKindSectionL2, elKindSectionL3, elKindSectionL4, elKindSectionL5:
+			if parent.kind == elKindPreamble {
+				docp.kind = lineKindEmpty
+				docp.prevKind = lineKindEmpty
+				docp.lineNum--
+				isTerm = true
+				continue
+			}
+
 			if term == elKindBlockOpen {
 				line = docp.parseParagraph(parent, el, line, term)
 				parent.addChild(el)
diff --git a/element.go b/element.go
index c0e94c1..9609570 100644
--- a/element.go
+++ b/element.go
@@ -843,11 +843,6 @@ func (el *element) toHTML(doc *Document, w io.Writer) {
 			doc.tocHTML(w)
 		}
 
-	case elKindPreamble:
-		if !doc.isEmbedded {
-			fmt.Fprint(w, _htmlPreambleBegin)
-		}
-
 	case elKindSectionDiscrete:
 		hmltWriteSectionDiscrete(doc, el, w)
 
@@ -1051,17 +1046,6 @@ func (el *element) toHTML(doc *Document, w io.Writer) {
 	}
 
 	switch el.kind {
-	case elKindPreamble:
-		if !doc.isEmbedded {
-			fmt.Fprint(w, "\n</div>")
-		}
-		if doc.tocIsEnabled && doc.tocPosition == metaValuePreamble {
-			doc.tocHTML(w)
-		}
-		if !doc.isEmbedded {
-			fmt.Fprint(w, "\n</div>")
-		}
-
 	case elKindSectionL1, elKindSectionL2, elKindSectionL3,
 		elKindSectionL4, elKindSectionL5:
 		if el.kind == elKindSectionL1 {
diff --git a/html_backend.go b/html_backend.go
index 1635328..b3f5adb 100644
--- a/html_backend.go
+++ b/html_backend.go
@@ -865,6 +865,21 @@ func htmlWriteBlockVideo(el *element, out io.Writer) {
 func htmlWriteBody(doc *Document, out *bytes.Buffer) {
 	if !doc.isEmbedded {
 		fmt.Fprint(out, "\n<div id=\"content\">")
+
+		if doc.preamble != nil {
+			fmt.Fprint(out, _lf+`<div id="preamble">`)
+			fmt.Fprint(out, _lf+`<div class="sectionbody">`)
+
+			if doc.preamble.child != nil {
+				doc.preamble.child.toHTML(doc, out)
+			}
+
+			fmt.Fprint(out, _lf+`</div>`)
+			if doc.tocIsEnabled && doc.tocPosition == metaValuePreamble {
+				doc.tocHTML(out)
+			}
+			fmt.Fprint(out, _lf+`</div>`)
+		}
 	}
 
 	if doc.content.child != nil {
diff --git a/html_template.go b/html_template.go
index cd173ab..c846fab 100644
--- a/html_template.go
+++ b/html_template.go
@@ -13,12 +13,6 @@ const (
 <meta name="viewport" content="width=device-width, initial-scale=1.0">`
 )
 
-const (
-	_htmlPreambleBegin = `
-<div id="preamble">
-<div class="sectionbody">`
-)
-
 // HTML templates for table of contents.
 const (
 	_htmlToCBegin = `
diff --git a/testdata/header_with_empty_line_test.txt b/testdata/header_with_empty_line_test.txt
index b2810db..f36f99b 100644
--- a/testdata/header_with_empty_line_test.txt
+++ b/testdata/header_with_empty_line_test.txt
@@ -17,14 +17,10 @@ Below is empty line with spaces.
 </div>
 </div>
 <div id="content">
-<div id="preamble">
-<div class="sectionbody">
 <div class="paragraph">
 <p>= Title</p>
 </div>
 </div>
-</div>
-</div>
 <div id="footer">
 <div id="footer-text">
 </div>
diff --git a/testdata/meta_showtitle_test.txt b/testdata/meta_showtitle_test.txt
index 7c5c047..e534c1c 100644
--- a/testdata/meta_showtitle_test.txt
+++ b/testdata/meta_showtitle_test.txt
@@ -11,10 +11,6 @@ output_call: ToHTMLBody
 </div>
 </div>
 <div id="content">
-<div id="preamble">
-<div class="sectionbody">
-</div>
-</div>
 </div>
 <div id="footer">
 <div id="footer-text">
@@ -32,10 +28,6 @@ output_call: ToHTMLBody
 </div>
 </div>
 <div id="content">
-<div id="preamble">
-<div class="sectionbody">
-</div>
-</div>
 </div>
 <div id="footer">
 <div id="footer-text">