Switch to chroma

go.mod

@@ -1 +1,7 @@
 module github.com/danog/blackfriday/v2
+
+go 1.17
+
+require github.com/alecthomas/chroma v0.9.4
+
+require github.com/dlclark/regexp2 v1.4.0 // indirect

go.sum

@@ -0,0 +1,15 @@
+github.com/alecthomas/chroma v0.9.4 h1:YL7sOAE3p8HS96T9km7RgvmsZIctqbK1qJ0b7hzed44=
+github.com/alecthomas/chroma v0.9.4/go.mod h1:jtJATyUxlIORhUOFNA9NZDWGAQ8wpxQQqNSB4rjA/1s=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/dlclark/regexp2 v1.4.0 h1:F1rxgk7p4uKjwIQxBs9oAXe5CqrXlCduYEJvrF4u93E=
+github.com/dlclark/regexp2 v1.4.0/go.mod h1:2pZnwuY/m+8K6iRw6wQdMtk+rH5tNGR1i55kozfMjCc=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

html.go

@@ -19,10 +19,13 @@ import (
 	"bytes"
 	"fmt"
 	"io"
-	"os"
-	"os/exec"
 	"regexp"
 	"strings"
+
+	"github.com/alecthomas/chroma"
+	"github.com/alecthomas/chroma/formatters/html"
+	"github.com/alecthomas/chroma/lexers"
+	"github.com/alecthomas/chroma/styles"
 )
 
 // HTMLFlags control optional behavior of HTML renderer.
@@ -769,25 +772,37 @@ func (r *HTMLRenderer) RenderNode(w io.Writer, node *Node, entering bool) WalkSt
 		r.cr(w)
 		r.tag(w, divTag[:len(divTag)-1], attrs)
 		r.tag(w, divTag[:len(divTag)-1], []string{`class="highlight"`})
-		r.tag(w, preTag[:len(preTag)-1], []string{`class="highlight"`})
-		r.out(w, codeTag)
 
-		buf := new(bytes.Buffer)
-		args := []string{"highlight", "-f", "html"}
-		if lang != "" {
-			args = append(args, "-l", lang)
-		}
-		cmd := exec.Command("rougify", args...) // nolint: gas
-		cmd.Stdin = strings.NewReader(string(node.Literal))
-		cmd.Stdout = buf
-		cmd.Stderr = os.Stderr
-		if e := cmd.Run(); e != nil {
-			panic(e)
-		}
-		r.out(w, buf.Bytes())
+		source := string(node.Literal)
+
+		// Determine lexer.
+		l := lexers.Get(lang)
+		if l == nil {
+			l = lexers.Analyse(source)
+		}
+		if l == nil {
+			l = lexers.Fallback
+		}
+		l = chroma.Coalesce(l)
+
+		// Determine formatter.
+		f := html.New(html.WithClasses(true))
+
+		// Determine style.
+		s := styles.Get("")
+		if s == nil {
+			s = styles.Fallback
+		}
+
+		it, err := l.Tokenise(nil, source)
+		if err != nil {
+			panic(err)
+		}
+
+		if err = f.Format(w, s, it); err != nil {
+			panic(err)
+		}
 
-		r.out(w, codeCloseTag)
-		r.out(w, preCloseTag)
 		r.out(w, divCloseTag)
 		r.out(w, divCloseTag)