!in operator

vlib/v/checker/checker.v

@@ -198,7 +198,7 @@ pub fn (c mut Checker) infix_expr(infix_expr mut ast.InfixExpr) table.Type {
 			return table.void_type
 		}
 	}
-	if infix_expr.op == .key_in {
+	if infix_expr.op in [.key_in, .not_in] {
 		if !(right.kind in [.array, .map, .string]) {
 			c.error('`in` can only be used with an array/map/string.', infix_expr.pos)
 		}
@@ -209,7 +209,8 @@ pub fn (c mut Checker) infix_expr(infix_expr mut ast.InfixExpr) table.Type {
 		if left_type == table.void_type || right_type == table.void_type {
 			return table.void_type
 		}
-		c.error('infix expr: cannot use `$right.name` (right) as `$left.name`', infix_expr.pos)
+		c.error('infix expr: cannot use `$right.name` (right expression) as `$left.name`',
+			infix_expr.pos)
 	}
 	if infix_expr.op.is_relational() {
 		return table.bool_type
@@ -752,7 +753,7 @@ pub fn (c mut Checker) array_init(array_init mut ast.ArrayInit) table.Type {
 				mut full_const_name := if it.mod == 'main' { it.name } else { it.mod + '.' +
 						it.name }
 				if obj := c.file.global_scope.find_const(full_const_name) {
-				   if cint := const_int_value( obj ) {
+					if cint := const_int_value(obj) {
 						fixed_size = cint
 					}
 				} else {

vlib/v/gen/cgen.v

@@ -1376,7 +1376,10 @@ fn (g mut Gen) infix_expr(node ast.InfixExpr) {
 		g.write(', ')
 		g.expr(node.right)
 		g.write(')')
-	} else if node.op == .key_in {
+	} else if node.op in [.key_in, .not_in] {
+		if node.op == .not_in {
+			g.write('!')
+		}
 		if right_sym.kind == .array {
 			match node.right {
 				ast.ArrayInit {

vlib/v/scanner/scanner.v

@@ -720,6 +720,10 @@ pub fn (s mut Scanner) scan() token.Token {
 				s.pos++
 				return s.new_token(.ne, '', 2)
 			}
+			else if nextc == `i` && s.text[s.pos+2] == `n` && !s.text[s.pos+3].is_letter() {
+				s.pos += 2
+				return s.new_token(.not_in, '', 3)
+			}
 			else {
 				return s.new_token(.not, '', 1)
 			}

vlib/v/token/token.v

@@ -44,6 +44,7 @@ pub enum Kind {
 	str_dollar
 	left_shift
 	right_shift
+	not_in // !in
 	// at // @
 	assign // =
 	decl_assign // :=
@@ -167,6 +168,7 @@ fn build_token_str() []string {
 	s[Kind.dotdot] = '..'
 	s[Kind.ellipsis] = '...'
 	s[Kind.comma] = ','
+	s[Kind.not_in] = '!in'
 	// s[Kind.at] = '@'
 	s[Kind.semicolon] = ';'
 	s[Kind.colon] = ':'
@@ -381,7 +383,7 @@ pub fn (tok Token) precedence() int {
 		.left_shift_assign, .right_shift_assign, .mult_assign, .xor_assign {
 			return int(Precedence.assign)
 		}
-		.key_in, .key_as {
+		.key_in, .not_in, .key_as {
 			return int(Precedence.in_as)
 		}
 		.logical_or, .and {
@@ -421,7 +423,7 @@ pub fn (k Kind) is_start_of_type() bool {
 pub fn (kind Kind) is_infix() bool {
 	return kind in [.plus, .minus, .mod, .mul, .div, .eq, .ne, .gt, .lt, .key_in,
 	//
-	.key_as, .ge, .le, .logical_or, .xor,
+	.key_as, .ge, .le, .logical_or, .xor, .not_in,
 	//
 	.and, .dot, .pipe, .amp, .left_shift, .right_shift]
 }