From cd3fa08cb15a5c07b87d967cea59653e63948a77 Mon Sep 17 00:00:00 2001
From: Mathias Leppich <mleppich@muhqu.de>
Date: Sun, 30 Mar 2014 21:57:58 +0200
Subject: [PATCH] fix issue #45: 'Fenced Code Blocks without a blank line
 before'

Add missing newline between paragraph and fenced code block within `firstPass()`.
---
 block.go    | 12 ++++++++----
 markdown.go | 13 +++++++++++++
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/block.go b/block.go
index 2636c52..cb3de22 100644
--- a/block.go
+++ b/block.go
@@ -101,7 +101,7 @@ func (p *parser) block(out *bytes.Buffer, data []byte) {
 		// }
 		// ```
 		if p.flags&EXTENSION_FENCED_CODE != 0 {
-			if i := p.fencedCode(out, data); i > 0 {
+			if i := p.fencedCode(out, data, true); i > 0 {
 				data = data[i:]
 				continue
 			}
@@ -599,7 +599,7 @@ func (p *parser) isFencedCode(data []byte, syntax **string, oldmarker string) (s
 	return
 }
 
-func (p *parser) fencedCode(out *bytes.Buffer, data []byte) int {
+func (p *parser) fencedCode(out *bytes.Buffer, data []byte, doRender bool) int {
 	var lang *string
 	beg, marker := p.isFencedCode(data, &lang, "")
 	if beg == 0 || beg >= len(data) {
@@ -631,7 +631,9 @@ func (p *parser) fencedCode(out *bytes.Buffer, data []byte) int {
 		}
 
 		// verbatim copy to the working buffer
-		work.Write(data[beg:end])
+		if doRender {
+			work.Write(data[beg:end])
+		}
 		beg = end
 	}
 
@@ -640,7 +642,9 @@ func (p *parser) fencedCode(out *bytes.Buffer, data []byte) int {
 		syntax = *lang
 	}
 
-	p.r.BlockCode(out, work.Bytes(), syntax)
+	if doRender {
+		p.r.BlockCode(out, work.Bytes(), syntax)
+	}
 
 	return beg
 }
diff --git a/markdown.go b/markdown.go
index 1b170e4..174bef8 100644
--- a/markdown.go
+++ b/markdown.go
@@ -305,6 +305,7 @@ func Markdown(input []byte, renderer Renderer, extensions int) []byte {
 // - expand tabs
 // - normalize newlines
 // - copy everything else
+// - add missing newlines before fenced code blocks
 func firstPass(p *parser, input []byte) []byte {
 	var out bytes.Buffer
 	tabSize := TAB_SIZE_DEFAULT
@@ -312,6 +313,8 @@ func firstPass(p *parser, input []byte) []byte {
 		tabSize = TAB_SIZE_EIGHT
 	}
 	beg, end := 0, 0
+	lastLineWasBlank := false
+	lastFencedCodeBlockEnd := 0
 	for beg < len(input) { // iterate over lines
 		if end = isReference(p, input[beg:], tabSize); end > 0 {
 			beg += end
@@ -321,6 +324,16 @@ func firstPass(p *parser, input []byte) []byte {
 				end++
 			}
 
+			// when last line was none blank and a fenced code block comes after
+			if !lastLineWasBlank && beg >= lastFencedCodeBlockEnd {
+				i := p.fencedCode(&out, append(input[beg:], '\n'), false)
+				if i > 0 {
+					out.WriteByte('\n') // need to inject additional linebreak
+					lastFencedCodeBlockEnd = beg + i
+				}
+			}
+			lastLineWasBlank = end == beg
+
 			// add the line body if present
 			if end > beg {
 				expandTabs(&out, input[beg:end], tabSize)