feat: Adds RenderBytesTo for rendering markdown to a externally provided writer

glamour.go

@@ -66,6 +66,16 @@ func RenderBytes(in []byte, stylePath string) ([]byte, error) {
 	return r.RenderBytes(in)
 }
 
+func RenderBytesTo(in []byte, stylePath string, w io.Writer) error {
+	r, err := NewTermRenderer(
+		WithStylePath(stylePath),
+	)
+	if err != nil {
+		return err
+	}
+	return r.RenderBytesTo(in, w)
+}
+
 // NewTermRenderer returns a new TermRenderer the given options.
 func NewTermRenderer(options ...TermRendererOption) (*TermRenderer, error) {
 	tr := &TermRenderer{
@@ -290,10 +300,15 @@ func (tr *TermRenderer) Render(in string) (string, error) {
 // RenderBytes returns the markdown rendered into a byte slice.
 func (tr *TermRenderer) RenderBytes(in []byte) ([]byte, error) {
 	var buf bytes.Buffer
-	err := tr.md.Convert(in, &buf)
+	err := tr.RenderBytesTo(in, &buf)
 	return buf.Bytes(), err
 }
 
+// RenderBytesTo renders markdown into the provided writer.
+func (tr *TermRenderer) RenderBytesTo(in []byte, w io.Writer) error {
+	return tr.md.Convert(in, w)
+}
+
 func getEnvironmentStyle() string {
 	glamourStyle := os.Getenv("GLAMOUR_STYLE")
 	if len(glamourStyle) == 0 {

glamour_test.go

@@ -325,3 +325,59 @@ func TestWithChromaFormatterCustom(t *testing.T) {
 
 	golden.RequireEqual(t, []byte(b))
 }
+
+func TestRenderBytesTo(t *testing.T) {
+	in, err := os.ReadFile(markdown)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var buf bytes.Buffer
+	err = RenderBytesTo(in, "dark", &buf)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	golden.RequireEqual(t, buf.Bytes())
+}
+
+func TestRenderBytesToWithCustomStyle(t *testing.T) {
+	in, err := os.ReadFile(markdown)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var buf bytes.Buffer
+	err = RenderBytesTo(in, "testdata/custom.style", &buf)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Compare with expected output
+	r, err := NewTermRenderer(WithStylePath("testdata/custom.style"))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expected, err := r.RenderBytes(in)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !bytes.Equal(expected, buf.Bytes()) {
+		t.Errorf("Output doesn't match expected result")
+	}
+}
+
+func TestRenderBytesToError(t *testing.T) {
+	in, err := os.ReadFile(markdown)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var buf bytes.Buffer
+	err = RenderBytesTo(in, "non-existent-style", &buf)
+	if err == nil {
+		t.Error("Expected error for non-existent style, got nil")
+	}
+}