add support for sprite-names fixes #192 (#194)

handlers/spriting.go

@@ -21,6 +21,7 @@ func init() {
 	libsass.RegisterSassFunc("sprite-map($glob, $spacing: 0px)", SpriteMap)
 	libsass.RegisterSassFunc("sprite-file($map, $name)", SpriteFile)
 	libsass.RegisterSassFunc("sprite-position($map, $file)", SpritePosition)
+	libsass.RegisterSassFunc("sprite-names($map)", SpriteNames)
 }
 
 // SpritePosition returns the position of the image in the sprite-map.
@@ -89,6 +90,36 @@ func SpriteFile(ctx context.Context, usv libsass.SassValue) (rsv *libsass.SassVa
 	return &res, err
 }
 
+func fileName(path string) string {
+	return strings.TrimSuffix(path, filepath.Ext(path))
+}
+
+// SpriteNames returns the names of all images in a sprite map
+func SpriteNames(ctx context.Context, usv libsass.SassValue) (*libsass.SassValue, error) {
+	comp, err := libsass.CompFromCtx(ctx)
+	if err != nil {
+		return nil, err
+	}
+	sprites := payload.Sprite(comp.Payload())
+
+	var glob string
+	if err := libsass.Unmarshal(usv, &glob); err != nil {
+		return nil, err
+	}
+
+	imgs := sprites.Get(glob)
+	if imgs == nil {
+		return nil, fmt.Errorf("sprite-map (%s) not found", glob)
+	}
+	paths := imgs.Paths()
+	for i := range paths {
+		paths[i] = fileName(paths[i])
+	}
+
+	lst, err := libsass.Marshal(paths)
+	return &lst, err
+}
+
 // Sprite returns the source and background position for an image in the
 // spritesheet.
 func Sprite(ctx context.Context, usv libsass.SassValue) (rsv *libsass.SassValue, err error) {

handlers/spriting_test.go

@@ -44,6 +44,43 @@ div.retina {
 	//   background-position: 10px -74px; }
 }
 
+func TestSpriteNames(t *testing.T) {
+	in := bytes.NewBufferString(`
+$map: sprite-map("*.png", 10px); // One argument
+@each $color in sprite_names($map) {
+        .#{$color} {
+          width:0px;
+        }
+      }
+`)
+
+	var out bytes.Buffer
+	comp, err := libsass.New(&out, in,
+		libsass.Payload(payload.New()),
+		libsass.ImgDir("../test/img"),
+		libsass.BuildDir("../test/build"),
+		libsass.ImgBuildDir("../test/build/img"),
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err := comp.Run(); err != nil {
+		t.Fatal(err)
+	}
+
+	e := `.139 {
+  width: 0px; }
+
+.140 {
+  width: 0px; }
+`
+
+	if out.String() != e {
+		t.Errorf("got: %q\nwanted: %q\n", out.String(), e)
+	}
+}
+
 func TestFuncSpriteFile(t *testing.T) {
 
 	comp, err := libsass.New(nil, nil,