Add full info string in fenced code blocks

According to common mark, the info string for a fenced code block can be any
non-whitespace string, so adjust the code to read a full string instead of
just the syntax name.

Fixes russross#410 in v2.

block.go

@@ -17,6 +17,7 @@ import (
 	"bytes"
 	"html"
 	"regexp"
+	"strings"
 
 	"github.com/shurcooL/sanitized_anchor_name"
 )
@@ -568,8 +569,8 @@ func (*Markdown) isHRule(data []byte) bool {
 
 // isFenceLine checks if there's a fence line (e.g., ``` or ``` go) at the beginning of data,
 // and returns the end index if so, or 0 otherwise. It also returns the marker found.
-// If syntax is not nil, it gets set to the syntax specified in the fence line.
-func isFenceLine(data []byte, syntax *string, oldmarker string) (end int, marker string) {
+// If info is not nil, it gets set to the syntax specified in the fence line.
+func isFenceLine(data []byte, info *string, oldmarker string) (end int, marker string) {
 	i, size := 0, 0
 
 	// skip up to three spaces
@@ -605,9 +606,9 @@ func isFenceLine(data []byte, syntax *string, oldmarker string) (end int, marker
 	}
 
 	// TODO(shurcooL): It's probably a good idea to simplify the 2 code paths here
-	// into one, always get the syntax, and discard it if the caller doesn't care.
-	if syntax != nil {
-		syn := 0
+	// into one, always get the info string, and discard it if the caller doesn't care.
+	if info != nil {
+		infoLength := 0
 		i = skipChar(data, i, ' ')
 
 		if i >= len(data) {
@@ -617,14 +618,14 @@ func isFenceLine(data []byte, syntax *string, oldmarker string) (end int, marker
 			return 0, ""
 		}
 
-		syntaxStart := i
+		infoStart := i
 
 		if data[i] == '{' {
 			i++
-			syntaxStart++
+			infoStart++
 
 			for i < len(data) && data[i] != '}' && data[i] != '\n' {
-				syn++
+				infoLength++
 				i++
 			}
 
@@ -634,31 +635,30 @@ func isFenceLine(data []byte, syntax *string, oldmarker string) (end int, marker
 
 			// strip all whitespace at the beginning and the end
 			// of the {} block
-			for syn > 0 && isspace(data[syntaxStart]) {
-				syntaxStart++
-				syn--
+			for infoLength > 0 && isspace(data[infoStart]) {
+				infoStart++
+				infoLength--
 			}
 
-			for syn > 0 && isspace(data[syntaxStart+syn-1]) {
-				syn--
+			for infoLength > 0 && isspace(data[infoStart+infoLength-1]) {
+				infoLength--
 			}
-
 			i++
+			i = skipChar(data, i, ' ')
 		} else {
-			for i < len(data) && !isspace(data[i]) {
-				syn++
+			for i < len(data) && !isverticalspace(data[i]){
+				infoLength++
 				i++
 			}
 		}
 
-		*syntax = string(data[syntaxStart : syntaxStart+syn])
+		*info = strings.TrimSpace(string(data[infoStart : infoStart+infoLength]))
 	}
 
-	i = skipChar(data, i, ' ')
-	if i >= len(data) || data[i] != '\n' {
-		if i == len(data) {
-			return i, marker
-		}
+	if i == len(data) {
+		return i, marker
+	}
+	if i > len(data) || data[i] != '\n' {
 		return 0, ""
 	}
 	return i + 1, marker // Take newline into account.
@@ -668,14 +668,14 @@ func isFenceLine(data []byte, syntax *string, oldmarker string) (end int, marker
 // or 0 otherwise. It writes to out if doRender is true, otherwise it has no side effects.
 // If doRender is true, a final newline is mandatory to recognize the fenced code block.
 func (p *Markdown) fencedCodeBlock(data []byte, doRender bool) int {
-	var syntax string
-	beg, marker := isFenceLine(data, &syntax, "")
+	var info string
+	beg, marker := isFenceLine(data, &info, "")
 	if beg == 0 || beg >= len(data) {
 		return 0
 	}
 
 	var work bytes.Buffer
-	work.Write([]byte(syntax))
+	work.Write([]byte(info))
 	work.WriteByte('\n')
 
 	for {

block_test.go

@@ -934,6 +934,9 @@ func TestFencedCodeBlock(t *testing.T) {
 		"``` go\nfunc foo() bool {\n\treturn true;\n}\n```\n",
 		"<pre><code class=\"language-go\">func foo() bool {\n\treturn true;\n}\n</code></pre>\n",
 
+		"``` go foo bar\nfunc foo() bool {\n\treturn true;\n}\n```\n",
+		"<pre><code class=\"language-go\">func foo() bool {\n\treturn true;\n}\n</code></pre>\n",
+
 		"``` c\n/* special & char < > \" escaping */\n```\n",
 		"<pre><code class=\"language-c\">/* special &amp; char &lt; &gt; &quot; escaping */\n</code></pre>\n",
 
@@ -1392,6 +1395,9 @@ func TestFencedCodeBlock_EXTENSION_NO_EMPTY_LINE_BEFORE_BLOCK(t *testing.T) {
 		"``` go\nfunc foo() bool {\n\treturn true;\n}\n```\n",
 		"<pre><code class=\"language-go\">func foo() bool {\n\treturn true;\n}\n</code></pre>\n",
 
+		"``` go foo bar\nfunc foo() bool {\n\treturn true;\n}\n```\n",
+		"<pre><code class=\"language-go\">func foo() bool {\n\treturn true;\n}\n</code></pre>\n",
+
 		"``` c\n/* special & char < > \" escaping */\n```\n",
 		"<pre><code class=\"language-c\">/* special &amp; char &lt; &gt; &quot; escaping */\n</code></pre>\n",
 
@@ -1630,10 +1636,10 @@ func TestCompletePage(t *testing.T) {
 func TestIsFenceLine(t *testing.T) {
 	tests := []struct {
 		data            []byte
-		syntaxRequested bool
+		infoRequested bool
 		wantEnd         int
 		wantMarker      string
-		wantSyntax      string
+		wantInfo      string
 	}{
 		{
 			data:       []byte("```"),
@@ -1647,7 +1653,7 @@ func TestIsFenceLine(t *testing.T) {
 		},
 		{
 			data:            []byte("```\nstuff here\n"),
-			syntaxRequested: true,
+			infoRequested: true,
 			wantEnd:         4,
 			wantMarker:      "```",
 		},
@@ -1657,34 +1663,48 @@ func TestIsFenceLine(t *testing.T) {
 		},
 		{
 			data:            []byte("```"),
-			syntaxRequested: true,
+			infoRequested: true,
 			wantEnd:         3,
 			wantMarker:      "```",
 		},
 		{
 			data:            []byte("``` go"),
-			syntaxRequested: true,
+			infoRequested: true,
 			wantEnd:         6,
 			wantMarker:      "```",
-			wantSyntax:      "go",
+			wantInfo:      "go",
+		},
+		{
+			data:            []byte("``` go foo bar"),
+			infoRequested: true,
+			wantEnd:         14,
+			wantMarker:      "```",
+			wantInfo:      "go foo bar",
+		},
+		{
+			data:            []byte("``` go foo bar  "),
+			infoRequested: true,
+			wantEnd:         16,
+			wantMarker:      "```",
+			wantInfo:      "go foo bar",
 		},
 	}
 
 	for _, test := range tests {
-		var syntax *string
-		if test.syntaxRequested {
-			syntax = new(string)
+		var info *string
+		if test.infoRequested {
+			info = new(string)
 		}
-		end, marker := isFenceLine(test.data, syntax, "```")
+		end, marker := isFenceLine(test.data, info, "```")
 		if got, want := end, test.wantEnd; got != want {
 			t.Errorf("got end %v, want %v", got, want)
 		}
 		if got, want := marker, test.wantMarker; got != want {
 			t.Errorf("got marker %q, want %q", got, want)
 		}
-		if test.syntaxRequested {
-			if got, want := *syntax, test.wantSyntax; got != want {
-				t.Errorf("got syntax %q, want %q", got, want)
+		if test.infoRequested {
+			if got, want := *info, test.wantInfo; got != want {
+				t.Errorf("got info string %q, want %q", got, want)
 			}
 		}
 	}

markdown.go

@@ -813,7 +813,17 @@ func ispunct(c byte) bool {
 
 // Test if a character is a whitespace character.
 func isspace(c byte) bool {
-	return c == ' ' || c == '\t' || c == '\n' || c == '\r' || c == '\f' || c == '\v'
+	return ishorizontalspace(c) || isverticalspace(c)
+}
+
+// Test if a character is a horizontal whitespace character.
+func ishorizontalspace(c byte) bool {
+	return c == ' ' || c == '\t'
+}
+
+// Test if a character is a vertical character.
+func isverticalspace(c byte) bool {
+	return c == '\n' || c == '\r' || c == '\f' || c == '\v'
 }
 
 // Test if a character is letter.