Merge pull request #211 from russross/issue-122

Fix issue 122: fenced code blocks inside blockquotes

block.go

@@ -891,13 +891,35 @@ func (p *parser) quotePrefix(data []byte) int {
 	return 0
 }
 
+// blockquote ends with at least one blank line
+// followed by something without a blockquote prefix
+func (p *parser) terminateBlockquote(data []byte, beg, end int) bool {
+	if p.isEmpty(data[beg:]) <= 0 {
+		return false
+	}
+	if end >= len(data) {
+		return true
+	}
+	return p.quotePrefix(data[end:]) == 0 && p.isEmpty(data[end:]) == 0
+}
+
 // parse a blockquote fragment
 func (p *parser) quote(out *bytes.Buffer, data []byte) int {
 	var raw bytes.Buffer
 	beg, end := 0, 0
 	for beg < len(data) {
 		end = beg
+		// Step over whole lines, collecting them. While doing that, check for
+		// fenced code and if one's found, incorporate it altogether,
+		// irregardless of any contents inside it
 		for data[end] != '\n' {
+			if p.flags&EXTENSION_FENCED_CODE != 0 {
+				if i := p.fencedCode(out, data[end:], false); i > 0 {
+					// -1 to compensate for the extra end++ after the loop:
+					end += i - 1
+					break
+				}
+			}
 			end++
 		}
 		end++
@@ -905,11 +927,7 @@ func (p *parser) quote(out *bytes.Buffer, data []byte) int {
 		if pre := p.quotePrefix(data[beg:]); pre > 0 {
 			// skip the prefix
 			beg += pre
-		} else if p.isEmpty(data[beg:]) > 0 &&
-			(end >= len(data) ||
-				(p.quotePrefix(data[end:]) == 0 && p.isEmpty(data[end:]) == 0)) {
-			// blockquote ends with at least one blank line
-			// followed by something without a blockquote prefix
+		} else if p.terminateBlockquote(data, beg, end) {
 			break
 		}
 
@@ -1342,6 +1360,14 @@ func (p *parser) paragraph(out *bytes.Buffer, data []byte) int {
 			return i
 		}
 
+		// if there's a fenced code block, paragraph is over
+		if p.flags&EXTENSION_FENCED_CODE != 0 {
+			if p.fencedCode(out, current, false) > 0 {
+				p.renderParagraph(out, data[:i])
+				return i
+			}
+		}
+
 		// if there's a definition list item, prev line is a definition term
 		if p.flags&EXTENSION_DEFINITION_LISTS != 0 {
 			if p.dliPrefix(current) != 0 {

block_test.go

@@ -14,6 +14,7 @@
 package blackfriday
 
 import (
+	"strings"
 	"testing"
 )
 
@@ -1065,6 +1066,118 @@ func TestFencedCodeBlock(t *testing.T) {
 	doTestsBlock(t, tests, EXTENSION_FENCED_CODE)
 }
 
+func TestFencedCodeInsideBlockquotes(t *testing.T) {
+	cat := func(s ...string) string { return strings.Join(s, "\n") }
+	var tests = []string{
+		cat("> ```go",
+			"package moo",
+			"",
+			"```",
+			""),
+		`<blockquote>
+<pre><code class="language-go">package moo
+
+</code></pre>
+</blockquote>
+`,
+		// -------------------------------------------
+		cat("> foo",
+			"> ",
+			"> ```go",
+			"package moo",
+			"```",
+			"> ",
+			"> goo.",
+			""),
+		`<blockquote>
+<p>foo</p>
+
+<pre><code class="language-go">package moo
+</code></pre>
+
+<p>goo.</p>
+</blockquote>
+`,
+		// -------------------------------------------
+		cat("> foo",
+			"> ",
+			"> quote",
+			"continues",
+			"```",
+			""),
+		`<blockquote>
+<p>foo</p>
+
+<p>quote
+continues
+` + "```" + `</p>
+</blockquote>
+`,
+		// -------------------------------------------
+		cat("> foo",
+			"> ",
+			"> ```go",
+			"package moo",
+			"```",
+			"> ",
+			"> goo.",
+			"> ",
+			"> ```go",
+			"package zoo",
+			"```",
+			"> ",
+			"> woo.",
+			""),
+		`<blockquote>
+<p>foo</p>
+
+<pre><code class="language-go">package moo
+</code></pre>
+
+<p>goo.</p>
+
+<pre><code class="language-go">package zoo
+</code></pre>
+
+<p>woo.</p>
+</blockquote>
+`,
+	}
+
+	// These 2 alternative forms of blockquoted fenced code blocks should produce same output.
+	forms := [2]string{
+		cat("> plain quoted text",
+			"> ```fenced",
+			"code",
+			" with leading single space correctly preserved",
+			"okay",
+			"```",
+			"> rest of quoted text"),
+		cat("> plain quoted text",
+			"> ```fenced",
+			"> code",
+			">  with leading single space correctly preserved",
+			"> okay",
+			"> ```",
+			"> rest of quoted text"),
+	}
+	want := `<blockquote>
+<p>plain quoted text</p>
+
+<pre><code class="language-fenced">code
+ with leading single space correctly preserved
+okay
+</code></pre>
+
+<p>rest of quoted text</p>
+</blockquote>
+`
+	tests = append(tests, forms[0], want)
+	tests = append(tests, forms[1], want)
+
+	doTestsBlock(t, tests, EXTENSION_FENCED_CODE)
+}
+
 func TestTable(t *testing.T) {
 	var tests = []string{
 		"a | b\n---|---\nc | d\n",

markdown.go

@@ -385,7 +385,6 @@ func MarkdownOptions(input []byte, renderer Renderer, opts Options) []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
@@ -393,7 +392,6 @@ 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 {
@@ -405,16 +403,13 @@ func firstPass(p *parser, input []byte) []byte {
 			}
 
 			if p.flags&EXTENSION_FENCED_CODE != 0 {
-				// when last line was none blank and a fenced code block comes after
+				// track fenced code block boundaries to suppress tab expansion
+				// inside them:
 				if beg >= lastFencedCodeBlockEnd {
 					if i := p.fencedCode(&out, input[beg:], false); i > 0 {
-						if !lastLineWasBlank {
-							out.WriteByte('\n') // need to inject additional linebreak
-						}
 						lastFencedCodeBlockEnd = beg + i
 					}
 				}
-				lastLineWasBlank = end == beg
 			}
 
 			// add the line body if present