Add struct tag support

variable-encoder.go

@@ -242,11 +242,19 @@ func (e *VariableEncoder) encodeStruct(v reflect.Value, t reflect.Type) error {
 	for i := 0; i < t.NumField(); i++ {
 		ft, fv := t.Field(i), v.Field(i)
 		if ft.PkgPath == "" { // Ignore unexported fields.
+			fieldName := ft.Name
+			if name, ok := ft.Tag.Lookup("typst"); ok {
+				// Omit fields that have their name set to "-".
+				if name == "-" {
+					continue
+				}
+				fieldName = name
+			}
+
 			if err := e.writeIndentationCharacters(); err != nil {
 				return err
 			}
-			// TODO: Allow name customization via struct tags
+			if err := e.writeStringLiteral([]byte(fieldName)); err != nil {
-			if err := e.writeStringLiteral([]byte(ft.Name)); err != nil {
 				return err
 			}
 			if err := e.writeString(": "); err != nil {

variable-encoder_test.go

@@ -126,6 +126,14 @@ func TestVariableEncoder(t *testing.T) {
 			Foo string
 			Bar int
 		}{"Hey!", 12345}, false, "(\n  \"Foo\": \"Hey!\",\n  \"Bar\": 12345,\n)"},
+		{"struct with tags", struct {
+			Foo string `typst:"foo"`
+			Bar int    `typst:"😀"`
+		}{"Hey!", 12345}, false, "(\n  \"foo\": \"Hey!\",\n  \"😀\": 12345,\n)"},
+		{"struct with tags omitting", struct {
+			Foo string `typst:"foo"`
+			Bar int    `typst:"-"`
+		}{"Hey!", 12345}, false, "(\n  \"foo\": \"Hey!\",\n)"},
 		{"struct empty", struct{}{}, false, "()"},
 		{"struct empty pointer", (*struct{})(nil), false, "none"},
 		{"map string string", map[string]string{"Foo": "Bar", "Foo2": "Electric Foogaloo"}, false, "(\n  \"Foo\": \"Bar\",\n  \"Foo2\": \"Electric Foogaloo\",\n)"},