helpers: Add support for French Guillemets

Fixes #3725

docs/content/readfiles/bfconfig.md

@@ -8,6 +8,11 @@
     Blackfriday flag: **`HTML_USE_SMARTYPANTS`** <br>
     Purpose: `false` disables smart punctuation substitutions, including smart quotes, smart dashes, smart fractions, etc. If `true`, it may be fine-tuned with the `angledQuotes`, `fractions`, `smartDashes`, and `latexDashes` flags (see below).
 
+`smartypantsQuotesNBSP`
+: default: **`false`** <br>
+    Blackfriday flag: **`HTML_SMARTYPANTS_QUOTES_NBSP`** <br>
+    Purpose: `true` enables French style Guillemets with non-breaking space inside the quotes.
+
 `angledQuotes`
 : default: **`false`**<br>
     Blackfriday flag: **`HTML_SMARTYPANTS_ANGLED_QUOTES`**<br>

helpers/content.go

@@ -63,6 +63,7 @@ func NewContentSpec(cfg config.Provider) *ContentSpec {
 // Blackfriday holds configuration values for Blackfriday rendering.
 type Blackfriday struct {
 	Smartypants                      bool
+	SmartypantsQuotesNBSP            bool
 	AngledQuotes                     bool
 	Fractions                        bool
 	HrefTargetBlank                  bool
@@ -81,6 +82,7 @@ func (c ContentSpec) NewBlackfriday() *Blackfriday {
 	defaultParam := map[string]interface{}{
 		"smartypants":                      true,
 		"angledQuotes":                     false,
+		"smartypantsQuotesNBSP":            false,
 		"fractions":                        true,
 		"hrefTargetBlank":                  false,
 		"smartDashes":                      true,
@@ -229,6 +231,10 @@ func (c ContentSpec) getHTMLRenderer(defaultFlags int, ctx *RenderingContext) bl
 		htmlFlags |= blackfriday.HTML_USE_SMARTYPANTS
 	}
 
+	if ctx.Config.SmartypantsQuotesNBSP {
+		htmlFlags |= blackfriday.HTML_SMARTYPANTS_QUOTES_NBSP
+	}
+
 	if ctx.Config.AngledQuotes {
 		htmlFlags |= blackfriday.HTML_SMARTYPANTS_ANGLED_QUOTES
 	}

helpers/content_test.go

@@ -171,6 +171,7 @@ func TestGetHTMLRendererAllFlags(t *testing.T) {
 		{blackfriday.HTML_USE_XHTML},
 		{blackfriday.HTML_FOOTNOTE_RETURN_LINKS},
 		{blackfriday.HTML_USE_SMARTYPANTS},
+		{blackfriday.HTML_SMARTYPANTS_QUOTES_NBSP},
 		{blackfriday.HTML_SMARTYPANTS_ANGLED_QUOTES},
 		{blackfriday.HTML_SMARTYPANTS_FRACTIONS},
 		{blackfriday.HTML_HREF_TARGET_BLANK},
@@ -186,6 +187,7 @@ func TestGetHTMLRendererAllFlags(t *testing.T) {
 	ctx.Config.PlainIDAnchors = true
 	ctx.Config.SmartDashes = true
 	ctx.Config.Smartypants = true
+	ctx.Config.SmartypantsQuotesNBSP = true
 	ctx.Config.SourceRelativeLinksEval = true
 	renderer := c.getHTMLRenderer(defaultFlags, ctx)
 	actualFlags := renderer.GetFlags()