Add old style Sass support

Author: bep

scss/common.go

@@ -76,6 +76,9 @@ type Options struct {
 	// to another URL or to return the body.
 	ImportResolver func(url string, prev string) (newURL string, body string, resolved bool)
 
+	// Used to indicate "old style" SASS for the input stream.
+	SassSyntax bool
+
 	// Source map settings
 	SourceMapFilename       string
 	SourceMapRoot           string

scss/libsass/transpiler.go

@@ -7,6 +7,7 @@
 package libsass
 
 import (
+	"bytes"
 	"io"
 	"io/ioutil"
 	"os"
@@ -30,12 +31,24 @@ func New(options scss.Options) (tocss.Transpiler, error) {
 // older SASS (.sass) files, but the main entry (src) currently needs to be SCSS.
 func (t *libsassTranspiler) Execute(dst io.Writer, src io.Reader) (tocss.Result, error) {
 	var result tocss.Result
-
-	b, err := ioutil.ReadAll(src)
-	if err != nil {
-		return result, err
+	var sourceStr string
+
+	if t.options.SassSyntax {
+		// LibSass does not support this directly, so have to handle the main SASS content
+		// special.
+		var buf bytes.Buffer
+		err := libs.ToScss(src, &buf)
+		if err != nil {
+			return result, err
+		}
+		sourceStr = buf.String()
+	} else {
+		b, err := ioutil.ReadAll(src)
+		if err != nil {
+			return result, err
+		}
+		sourceStr = string(b)
 	}
-	sourceStr := string(b)
 
 	dataCtx := libs.SassMakeDataContext(sourceStr)
 

scss/libsass/transpiler_test.go

@@ -41,6 +41,25 @@ div { p { color: $white; } }`)
 	assert.Equal("div p {\n  color: #fff; }\n", dst.String())
 }
 
+func TestSassSyntax(t *testing.T) {
+	assert := require.New(t)
+	src := bytes.NewBufferString(`
+$color: #333;
+
+.content-navigation
+  border-color: $color
+`)
+
+	var dst bytes.Buffer
+
+	transpiler, err := New(scss.Options{OutputStyle: scss.CompressedStyle, SassSyntax: true})
+	assert.NoError(err)
+
+	_, err = transpiler.Execute(&dst, src)
+	assert.NoError(err)
+	assert.Equal(".content-navigation{border-color:#333}\n", dst.String())
+}
+
 func TestOutputStyle(t *testing.T) {
 	assert := require.New(t)
 	src := bytes.NewBufferString(`