Adding upstream version 0.28.1.

Signed-off-by: Daniel Baumann <daniel@debian.org>

core/validators/equal.go

@@ -0,0 +1,85 @@
+package validators
+
+import (
+	"reflect"
+
+	validation "github.com/go-ozzo/ozzo-validation/v4"
+)
+
+// Equal checks whether the validated value matches another one from the same type.
+//
+// It expects the compared values to be from the same type and works
+// with booleans, numbers, strings and their pointer variants.
+//
+// If one of the value is pointer, the comparison is based on its
+// underlying value (when possible to determine).
+//
+// Note that empty/zero values are also compared (this differ from other validation.RuleFunc).
+//
+// Example:
+//
+//	validation.Field(&form.PasswordConfirm, validation.By(validators.Equal(form.Password)))
+func Equal[T comparable](valueToCompare T) validation.RuleFunc {
+	return func(value any) error {
+		if compareValues(value, valueToCompare) {
+			return nil
+		}
+
+		return validation.NewError("validation_values_mismatch", "Values don't match.")
+	}
+}
+
+func compareValues(a, b any) bool {
+	if a == b {
+		return true
+	}
+
+	if checkIsNil(a) && checkIsNil(b) {
+		return true
+	}
+
+	var result bool
+
+	defer func() {
+		if err := recover(); err != nil {
+			result = false
+		}
+	}()
+
+	reflectA := reflect.ValueOf(a)
+	reflectB := reflect.ValueOf(b)
+
+	dereferencedA := dereference(reflectA)
+	dereferencedB := dereference(reflectB)
+	if dereferencedA.CanInterface() && dereferencedB.CanInterface() {
+		result = dereferencedA.Interface() == dereferencedB.Interface()
+	}
+
+	return result
+}
+
+// note https://github.com/golang/go/issues/51649
+func checkIsNil(value any) bool {
+	if value == nil {
+		return true
+	}
+
+	var result bool
+
+	defer func() {
+		if err := recover(); err != nil {
+			result = false
+		}
+	}()
+
+	result = reflect.ValueOf(value).IsNil()
+
+	return result
+}
+
+func dereference(v reflect.Value) reflect.Value {
+	for v.Kind() == reflect.Pointer {
+		v = v.Elem()
+	}
+	return v
+}