Add Smartypants support for French Guillemets

This is a port of the fix for #378 in v1.

Fixes #380

html.go

@@ -44,6 +44,7 @@ const (
 	SmartypantsDashes                             // Enable smart dashes (with Smartypants)
 	SmartypantsLatexDashes                        // Enable LaTeX-style dashes (with Smartypants)
 	SmartypantsAngledQuotes                       // Enable angled double quotes (with Smartypants) for double quotes rendering
+	SmartypantsQuotesNBSP                         // Enable « French guillemets » (with Smartypants)
 	TOC                                           // Generate a table of contents
 
 	TagName               = "[A-Za-z][A-Za-z0-9-]*"

inline_test.go

@@ -1034,6 +1034,18 @@ func TestSmartDoubleQuotes(t *testing.T) {
 	doTestsInlineParam(t, tests, TestParams{HTMLFlags: Smartypants})
 }
 
+func TestSmartDoubleQuotesNBSP(t *testing.T) {
+	var tests = []string{
+		"this should be normal \"quoted\" text.\n",
+		"<p>this should be normal &ldquo;&nbsp;quoted&nbsp;&rdquo; text.</p>\n",
+		"this \" single double\n",
+		"<p>this &ldquo;&nbsp; single double</p>\n",
+		"two pair of \"some\" quoted \"text\".\n",
+		"<p>two pair of &ldquo;&nbsp;some&nbsp;&rdquo; quoted &ldquo;&nbsp;text&nbsp;&rdquo;.</p>\n"}
+
+	doTestsInlineParam(t, tests, TestParams{HTMLFlags: Smartypants | SmartypantsQuotesNBSP})
+}
+
 func TestSmartAngledDoubleQuotes(t *testing.T) {
 	var tests = []string{
 		"this should be angled \"quoted\" text.\n",
@@ -1046,6 +1058,18 @@ func TestSmartAngledDoubleQuotes(t *testing.T) {
 	doTestsInlineParam(t, tests, TestParams{HTMLFlags: Smartypants | SmartypantsAngledQuotes})
 }
 
+func TestSmartAngledDoubleQuotesNBSP(t *testing.T) {
+	var tests = []string{
+		"this should be angled \"quoted\" text.\n",
+		"<p>this should be angled &laquo;&nbsp;quoted&nbsp;&raquo; text.</p>\n",
+		"this \" single double\n",
+		"<p>this &laquo;&nbsp; single double</p>\n",
+		"two pair of \"some\" quoted \"text\".\n",
+		"<p>two pair of &laquo;&nbsp;some&nbsp;&raquo; quoted &laquo;&nbsp;text&nbsp;&raquo;.</p>\n"}
+
+	doTestsInlineParam(t, tests, TestParams{HTMLFlags: Smartypants | SmartypantsAngledQuotes | SmartypantsQuotesNBSP})
+}
+
 func TestSmartFractions(t *testing.T) {
 	var tests = []string{
 		"1/2, 1/4 and 3/4; 1/4th and 3/4ths\n",
@@ -1140,3 +1164,13 @@ func TestSkipHTML(t *testing.T) {
 		"<p>text inline html more text</p>\n",
 	}, TestParams{HTMLFlags: SkipHTML})
 }
+
+func BenchmarkSmartDoubleQuotes(b *testing.B) {
+	params := TestParams{HTMLFlags: Smartypants}
+	params.extensions |= Autolink | Strikethrough
+	params.HTMLFlags |= UseXHTML
+
+	for i := 0; i < b.N; i++ {
+		runMarkdown("this should be normal \"quoted\" text.\n", params)
+	}
+}

smartypants.go

@@ -42,7 +42,7 @@ func isdigit(c byte) bool {
 	return c >= '0' && c <= '9'
 }
 
-func smartQuoteHelper(out *bytes.Buffer, previousChar byte, nextChar byte, quote byte, isOpen *bool) bool {
+func smartQuoteHelper(out *bytes.Buffer, previousChar byte, nextChar byte, quote byte, isOpen *bool, addNBSP bool) bool {
 	// edge of the buffer is likely to be a tag that we don't get to see,
 	// so we treat it like text sometimes
 
@@ -99,6 +99,12 @@ func smartQuoteHelper(out *bytes.Buffer, previousChar byte, nextChar byte, quote
 		*isOpen = false
 	}
 
+	// Note that with the limited lookahead, this non-breaking
+	// space will also be appended to single double quotes.
+	if addNBSP && !*isOpen {
+		out.WriteString("&nbsp;")
+	}
+
 	out.WriteByte('&')
 	if *isOpen {
 		out.WriteByte('l')
@@ -107,6 +113,11 @@ func smartQuoteHelper(out *bytes.Buffer, previousChar byte, nextChar byte, quote
 	}
 	out.WriteByte(quote)
 	out.WriteString("quo;")
+
+	if addNBSP && *isOpen {
+		out.WriteString("&nbsp;")
+	}
+
 	return true
 }
 
@@ -119,7 +130,7 @@ func (r *SPRenderer) smartSingleQuote(out *bytes.Buffer, previousChar byte, text
 			if len(text) >= 3 {
 				nextChar = text[2]
 			}
-			if smartQuoteHelper(out, previousChar, nextChar, 'd', &r.inDoubleQuote) {
+			if smartQuoteHelper(out, previousChar, nextChar, 'd', &r.inDoubleQuote, false) {
 				return 1
 			}
 		}
@@ -144,7 +155,7 @@ func (r *SPRenderer) smartSingleQuote(out *bytes.Buffer, previousChar byte, text
 	if len(text) > 1 {
 		nextChar = text[1]
 	}
-	if smartQuoteHelper(out, previousChar, nextChar, 's', &r.inSingleQuote) {
+	if smartQuoteHelper(out, previousChar, nextChar, 's', &r.inSingleQuote, false) {
 		return 0
 	}
 
@@ -208,13 +219,13 @@ func (r *SPRenderer) smartDashLatex(out *bytes.Buffer, previousChar byte, text [
 	return 0
 }
 
-func (r *SPRenderer) smartAmpVariant(out *bytes.Buffer, previousChar byte, text []byte, quote byte) int {
+func (r *SPRenderer) smartAmpVariant(out *bytes.Buffer, previousChar byte, text []byte, quote byte, addNBSP bool) int {
 	if bytes.HasPrefix(text, []byte("&quot;")) {
 		nextChar := byte(0)
 		if len(text) >= 7 {
 			nextChar = text[6]
 		}
-		if smartQuoteHelper(out, previousChar, nextChar, quote, &r.inDoubleQuote) {
+		if smartQuoteHelper(out, previousChar, nextChar, quote, &r.inDoubleQuote, addNBSP) {
 			return 5
 		}
 	}
@@ -227,12 +238,15 @@ func (r *SPRenderer) smartAmpVariant(out *bytes.Buffer, previousChar byte, text
 	return 0
 }
 
-func (r *SPRenderer) smartAmp(out *bytes.Buffer, previousChar byte, text []byte) int {
+func (r *SPRenderer) smartAmp(angledQuotes, addNBSP bool) func(*bytes.Buffer, byte, []byte) int {
-	return r.smartAmpVariant(out, previousChar, text, 'd')
+	var quote byte = 'd'
-}
+	if angledQuotes {
+		quote = 'a'
+	}
 
-func (r *SPRenderer) smartAmpAngledQuote(out *bytes.Buffer, previousChar byte, text []byte) int {
+	return func(out *bytes.Buffer, previousChar byte, text []byte) int {
-	return r.smartAmpVariant(out, previousChar, text, 'a')
+		return r.smartAmpVariant(out, previousChar, text, quote, addNBSP)
+	}
 }
 
 func (r *SPRenderer) smartPeriod(out *bytes.Buffer, previousChar byte, text []byte) int {
@@ -256,7 +270,7 @@ func (r *SPRenderer) smartBacktick(out *bytes.Buffer, previousChar byte, text []
 		if len(text) >= 3 {
 			nextChar = text[2]
 		}
-		if smartQuoteHelper(out, previousChar, nextChar, 'd', &r.inDoubleQuote) {
+		if smartQuoteHelper(out, previousChar, nextChar, 'd', &r.inDoubleQuote, false) {
 			return 1
 		}
 	}
@@ -340,7 +354,7 @@ func (r *SPRenderer) smartDoubleQuoteVariant(out *bytes.Buffer, previousChar byt
 	if len(text) > 1 {
 		nextChar = text[1]
 	}
-	if !smartQuoteHelper(out, previousChar, nextChar, quote, &r.inDoubleQuote) {
+	if !smartQuoteHelper(out, previousChar, nextChar, quote, &r.inDoubleQuote, false) {
 		out.WriteString("&quot;")
 	}
 
@@ -370,13 +384,31 @@ type smartCallback func(out *bytes.Buffer, previousChar byte, text []byte) int
 
 // NewSmartypantsRenderer constructs a Smartypants renderer object.
 func NewSmartypantsRenderer(flags HTMLFlags) *SPRenderer {
-	var r SPRenderer
+	var (
+		r SPRenderer
+
+		smartAmpAngled      = r.smartAmp(true, false)
+		smartAmpAngledNBSP  = r.smartAmp(true, true)
+		smartAmpRegular     = r.smartAmp(false, false)
+		smartAmpRegularNBSP = r.smartAmp(false, true)
+
+		addNBSP = flags&SmartypantsQuotesNBSP != 0
+	)
+
 	if flags&SmartypantsAngledQuotes == 0 {
 		r.callbacks['"'] = r.smartDoubleQuote
-		r.callbacks['&'] = r.smartAmp
+		if !addNBSP {
+			r.callbacks['&'] = smartAmpRegular
+		} else {
+			r.callbacks['&'] = smartAmpRegularNBSP
+		}
 	} else {
 		r.callbacks['"'] = r.smartAngledDoubleQuote
-		r.callbacks['&'] = r.smartAmpAngledQuote
+		if !addNBSP {
+			r.callbacks['&'] = smartAmpAngled
+		} else {
+			r.callbacks['&'] = smartAmpAngledNBSP
+		}
 	}
 	r.callbacks['\''] = r.smartSingleQuote
 	r.callbacks['('] = r.smartParens