Merge pull request #90 from ucan-wg/fix/extended-field-names

Add support for extended field names in selectors

pkg/policy/selector/parsing.go

@@ -13,7 +13,17 @@ import (
 var (
 	indexRegex = regexp.MustCompile(`^-?\d+$`)
 	sliceRegex = regexp.MustCompile(`^((\-?\d+:\-?\d*)|(\-?\d*:\-?\d+))$`)
-	fieldRegex = regexp.MustCompile(`^\.[a-zA-Z_-]*?$`)
+
+	// Field name requirements:
+	// - Must start with ASCII letter, Unicode letter, or underscore
+	// - Can contain:
+	//   - ASCII letters (a-z, A-Z)
+	//   - ASCII digits (0-9)
+	//   - Unicode letters (\p{L})
+	//   - Dollar sign ($)
+	//   - Underscore (_)
+	//   - Hyphen (-)
+	fieldRegex = regexp.MustCompile(`^\.[a-zA-Z_\p{L}][a-zA-Z0-9$_\p{L}\-]*$`)
 )
 
 func Parse(str string) (Selector, error) {

pkg/policy/selector/parsing_test.go

@@ -6,6 +6,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/require"
+
 	"github.com/ucan-wg/go-ucan/pkg/policy/limits"
 )
 
@@ -575,6 +576,50 @@ func TestParse(t *testing.T) {
 		require.Error(t, err)
 	})
 
+	t.Run("extended field names", func(t *testing.T) {
+		validFields := []string{
+			".basic",
+			".user_name",
+			".user-name",
+			".userName$special",
+			".αβγ",        // Greek letters
+			".użytkownik", // Polish characters
+			".用户",         // Chinese characters
+			".사용자",        // Korean characters
+			"._private",
+			".number123",
+			".camelCase",
+			".snake_case",
+			".kebab-case",
+			".mixed_kebab-case",
+			".with$dollar",
+			".MIXED_Case_123",
+			".unicodeø",
+		}
+
+		for _, field := range validFields {
+			sel, err := Parse(field)
+			require.NoError(t, err, "field: %s", field)
+			require.NotNil(t, sel)
+		}
+
+		invalidFields := []string{
+			".123number",         // Can't start with digit
+			".@special",          // @ not allowed
+			".space name",        // No spaces
+			".#hashtag",          // No #
+			".name!",             // No !
+			".{brackets}",        // No brackets
+			".name/with/slashes", // No slashes
+		}
+
+		for _, field := range invalidFields {
+			sel, err := Parse(field)
+			require.Error(t, err, "field: %s", field)
+			require.Nil(t, sel)
+		}
+	})
+
 	t.Run("integer overflow", func(t *testing.T) {
 		sel, err := Parse(fmt.Sprintf(".[%d]", limits.MaxInt53+1))
 		require.Error(t, err)