Use pkg deref in vm

builtin/builtin.go

@@ -920,8 +920,7 @@ var Builtins = []*Function{
 			var arr []any
 
 			for _, arg := range args {
-				arg = runtime.Deref(arg)
-				v := reflect.ValueOf(arg)
+				v := reflect.ValueOf(deref.Deref(arg))
 
 				if v.Kind() != reflect.Slice && v.Kind() != reflect.Array {
 					return nil, 0, fmt.Errorf("cannot concat %s", v.Kind())

expr_test.go

@@ -316,9 +316,9 @@ func ExampleOperator_Decimal() {
 	code := `A + B - C`
 
 	type Env struct {
-		A, B, C   Decimal
-		Sub       func(a, b Decimal) Decimal
-		Add       func(a, b Decimal) Decimal
+		A, B, C Decimal
+		Sub     func(a, b Decimal) Decimal
+		Add     func(a, b Decimal) Decimal
 	}
 
 	options := []expr.Option{
@@ -334,11 +334,11 @@ func ExampleOperator_Decimal() {
 	}
 
 	env := Env{
-		A: Decimal{3},
-		B: Decimal{2},
-		C: Decimal{1},
+		A:   Decimal{3},
+		B:   Decimal{2},
+		C:   Decimal{1},
 		Sub: func(a, b Decimal) Decimal { return Decimal{a.N - b.N} },
-		Add: func(a, b Decimal) Decimal { return Decimal{a.N + b.N}  },
+		Add: func(a, b Decimal) Decimal { return Decimal{a.N + b.N} },
 	}
 
 	output, err := expr.Run(program, env)
@@ -1358,21 +1358,6 @@ func TestExpr_fetch_from_func(t *testing.T) {
 	assert.Contains(t, err.Error(), "cannot fetch Value from func()")
 }
 
-func TestExpr_fetch_from_interface(t *testing.T) {
-	type FooBar struct {
-		Value string
-	}
-	foobar := &FooBar{"waldo"}
-	var foobarAny any = foobar
-	var foobarPtrAny any = &foobarAny
-
-	res, err := expr.Eval("foo.Value", map[string]any{
-		"foo": foobarPtrAny,
-	})
-	assert.NoError(t, err)
-	assert.Equal(t, "waldo", res)
-}
-
 func TestExpr_map_default_values(t *testing.T) {
 	env := map[string]any{
 		"foo": map[string]string{},

test/deref/deref_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"testing"
 
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
 	"github.com/expr-lang/expr"
@@ -237,3 +238,18 @@ func TestDeref_сommutative(t *testing.T) {
 		})
 	}
 }
+
+func TestDeref_fetch_from_interface_mix_pointer(t *testing.T) {
+	type FooBar struct {
+		Value string
+	}
+	foobar := &FooBar{"waldo"}
+	var foobarAny any = foobar
+	var foobarPtrAny any = &foobarAny
+
+	res, err := expr.Eval("foo.Value", map[string]any{
+		"foo": foobarPtrAny,
+	})
+	assert.NoError(t, err)
+	assert.Equal(t, "waldo", res)
+}

vm/runtime/runtime.go

@@ -6,20 +6,13 @@ import (
 	"fmt"
 	"math"
 	"reflect"
-)
 
-func deref(kind reflect.Kind, value reflect.Value) (reflect.Kind, reflect.Value) {
-	for kind == reflect.Ptr || kind == reflect.Interface {
-		value = value.Elem()
-		kind = value.Kind()
-	}
-	return kind, value
-}
+	"github.com/expr-lang/expr/internal/deref"
+)
 
 func Fetch(from, i any) any {
 	v := reflect.ValueOf(from)
-	kind := v.Kind()
-	if kind == reflect.Invalid {
+	if v.Kind() == reflect.Invalid {
 		panic(fmt.Sprintf("cannot fetch %v from %T", i, from))
 	}
 
@@ -37,11 +30,9 @@ func Fetch(from, i any) any {
 	// a value, when they are accessed through a pointer we don't want to
 	// copy them to a value.
 	// De-reference everything if necessary (interface and pointers)
-	kind, v = deref(kind, v)
+	v = deref.Value(v)
 
-	// TODO: We can create separate opcodes for each of the cases below to make
-	// the little bit faster.
-	switch kind {
+	switch v.Kind() {
 	case reflect.Array, reflect.Slice, reflect.String:
 		index := ToInt(i)
 		if index < 0 {
@@ -144,27 +135,6 @@ func FetchMethod(from any, method *Method) any {
 	panic(fmt.Sprintf("cannot fetch %v from %T", method.Name, from))
 }
 
-func Deref(i any) any {
-	if i == nil {
-		return nil
-	}
-
-	v := reflect.ValueOf(i)
-
-	for v.Kind() == reflect.Ptr || v.Kind() == reflect.Interface {
-		if v.IsNil() {
-			return nil
-		}
-		v = v.Elem()
-	}
-
-	if v.IsValid() {
-		return v.Interface()
-	}
-
-	panic(fmt.Sprintf("cannot dereference %v", i))
-}
-
 func Slice(array, from, to any) any {
 	v := reflect.ValueOf(array)
 

vm/vm.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/expr-lang/expr/builtin"
 	"github.com/expr-lang/expr/file"
+	"github.com/expr-lang/expr/internal/deref"
 	"github.com/expr-lang/expr/vm/runtime"
 )
 
@@ -436,7 +437,7 @@ func (vm *VM) Run(program *Program, env any) (_ any, err error) {
 
 		case OpDeref:
 			a := vm.pop()
-			vm.push(runtime.Deref(a))
+			vm.push(deref.Deref(a))
 
 		case OpIncrementIndex:
 			vm.scope().Index++