Add toPairs() and fromPairs()

Author: antonmedv

builtin/builtin.go

@@ -584,6 +584,70 @@ var Builtins = []*ast.Function{
 			return anyType, fmt.Errorf("cannot get values from %s", args[0])
 		},
 	},
+	{
+		Name: "toPairs",
+		Func: func(args ...any) (any, error) {
+			if len(args) != 1 {
+				return nil, fmt.Errorf("invalid number of arguments (expected 1, got %d)", len(args))
+			}
+			v := reflect.ValueOf(args[0])
+			if v.Kind() != reflect.Map {
+				return nil, fmt.Errorf("cannot transform %s to pairs", v.Kind())
+			}
+			keys := v.MapKeys()
+			out := make([][2]any, len(keys))
+			for i, key := range keys {
+				out[i] = [2]any{key.Interface(), v.MapIndex(key).Interface()}
+			}
+			return out, nil
+		},
+		Validate: func(args []reflect.Type) (reflect.Type, error) {
+			if len(args) != 1 {
+				return anyType, fmt.Errorf("invalid number of arguments (expected 1, got %d)", len(args))
+			}
+			switch kind(args[0]) {
+			case reflect.Interface, reflect.Map:
+				return arrayType, nil
+			}
+			return anyType, fmt.Errorf("cannot transform %s to pairs", args[0])
+		},
+	},
+	{
+		Name: "fromPairs",
+		Func: func(args ...any) (any, error) {
+			if len(args) != 1 {
+				return nil, fmt.Errorf("invalid number of arguments (expected 1, got %d)", len(args))
+			}
+			v := reflect.ValueOf(args[0])
+			if v.Kind() != reflect.Slice && v.Kind() != reflect.Array {
+				return nil, fmt.Errorf("cannot transform %s from pairs", v)
+			}
+			out := reflect.MakeMap(mapType)
+			for i := 0; i < v.Len(); i++ {
+				pair := deref(v.Index(i))
+				if pair.Kind() != reflect.Array && pair.Kind() != reflect.Slice {
+					return nil, fmt.Errorf("invalid pair %v", pair)
+				}
+				if pair.Len() != 2 {
+					return nil, fmt.Errorf("invalid pair length %v", pair)
+				}
+				key := pair.Index(0)
+				value := pair.Index(1)
+				out.SetMapIndex(key, value)
+			}
+			return out.Interface(), nil
+		},
+		Validate: func(args []reflect.Type) (reflect.Type, error) {
+			if len(args) != 1 {
+				return anyType, fmt.Errorf("invalid number of arguments (expected 1, got %d)", len(args))
+			}
+			switch kind(args[0]) {
+			case reflect.Interface, reflect.Slice, reflect.Array:
+				return mapType, nil
+			}
+			return anyType, fmt.Errorf("cannot transform %s from pairs", args[0])
+		},
+	},
 	{
 		Name: "sort",
 		Func: func(args ...any) (any, error) {

builtin/builtin_test.go

@@ -94,6 +94,10 @@ func TestBuiltin(t *testing.T) {
 		{`get({foo: 1, bar: 2}, "unknown")`, nil},
 		{`"foo" in keys({foo: 1, bar: 2})`, true},
 		{`1 in values({foo: 1, bar: 2})`, true},
+		{`len(toPairs({foo: 1, bar: 2}))`, 2},
+		{`len(toPairs({}))`, 0},
+		{`fromPairs([["foo", 1], ["bar", 2]])`, map[any]any{"foo": 1, "bar": 2}},
+		{`fromPairs(toPairs({foo: 1, bar: 2}))`, map[any]any{"foo": 1, "bar": 2}},
 		{`groupBy(1..9, # % 2)`, map[any][]any{0: {2, 4, 6, 8}, 1: {1, 3, 5, 7, 9}}},
 		{`groupBy(1..9, # % 2)[0]`, []any{2, 4, 6, 8}},
 		{`groupBy(1..3, # > 1)[true]`, []any{2, 3}},

builtin/utils.go

@@ -9,8 +9,8 @@ var (
 	anyType     = reflect.TypeOf(new(any)).Elem()
 	integerType = reflect.TypeOf(0)
 	floatType   = reflect.TypeOf(float64(0))
-	stringType  = reflect.TypeOf("")
 	arrayType   = reflect.TypeOf([]any{})
+	mapType     = reflect.TypeOf(map[any]any{})
 )
 
 func kind(t reflect.Type) reflect.Kind {