create separate Props.CSS func

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 All notable changes to this project will be documented in this file.
 
+### v0.1.2
+
+- Move the `Props` CSS writing into a `Props.CSS` func, so it can be used in isolation of the `Style` struct.
+  - This allows for the `Props` CSS to be used in other contexts, such as in a `style` attribute in HTML.
+
 ### v0.1.1
 
 Added new props:

style.go

@@ -118,19 +118,15 @@ type (
 	}
 )
 
-// CSS writes the CSS representation of the style to the writer.
-func (s *Style) CSS(w io.Writer) error {
-	propsValue := reflect.ValueOf(s.Props)
-	propsType := reflect.TypeOf(s.Props)
-
-	if _, err := fmt.Fprintf(w, "%s{", s.Selector); err != nil {
-		return err
-	}
+// CSS writes the CSS representation of the props to the writer.
+func (p *Props) CSS(w io.Writer) error {
+	value := reflect.ValueOf(*p)
+	typ := reflect.TypeOf(*p)
 
 	// Iterate over the fields of the Props struct and write the CSS properties to the writer.
-	for i := 0; i < propsValue.NumField(); i++ {
-		fieldValue := propsValue.Field(i)
-		fieldType := propsType.Field(i)
+	for i := 0; i < value.NumField(); i++ {
+		fieldValue := value.Field(i)
+		fieldType := typ.Field(i)
 
 		if fieldValue.IsZero() {
 			continue
@@ -145,6 +141,20 @@ func (s *Style) CSS(w io.Writer) error {
 		}
 	}
 
+	return nil
+}
+
+// CSS writes the CSS representation of the style to the writer.
+func (s *Style) CSS(w io.Writer) error {
+	if _, err := fmt.Fprintf(w, "%s{", s.Selector); err != nil {
+		return err
+	}
+
+	// Write the standard properties to the writer.
+	if err := s.Props.CSS(w); err != nil {
+		return err
+	}
+
 	// Write the custom properties to the writer.
 	for _, prop := range s.CustomProps {
 		if _, err := fmt.Fprintf(w, "%s:%s;", prop.Attr, prop.Value); err != nil {

style_test.go

@@ -20,6 +20,25 @@ func runTest(t *testing.T, st *Style, expected string) {
 	}
 }
 
+func TestProps_CSS(t *testing.T) {
+	testCases := map[Props]string{
+		{}: "",
+		{BackgroundColor: props.ColorRGBA(0, 0, 0, 255)}:      "background-color:rgba(0,0,0,1.00);",
+		{Margin: props.UnitPx(10), Padding: props.UnitPx(10)}: "margin:10px;padding:10px;",
+	}
+	for prop, expected := range testCases {
+		var buf bytes.Buffer
+		err := prop.CSS(&buf)
+		if err != nil {
+			t.Errorf("unexpected error: %v", err)
+		}
+
+		if buf.String() != expected {
+			t.Errorf("expected %q, got %q", expected, buf.String())
+		}
+	}
+}
+
 func TestStyle_Empty(t *testing.T) {
 	st := &Style{Selector: ".test", Props: Props{}}
 	css := ".test{}"