parser/cgen: is keyword

vlib/v/checker/checker.v

@@ -196,6 +196,9 @@ pub fn (c mut Checker) infix_expr(infix_expr mut ast.InfixExpr) table.Type {
 	left_type := c.expr(infix_expr.left)
 	infix_expr.left_type = left_type
 	c.expected_type = left_type
+	if infix_expr.op == .key_is {
+		return table.bool_type
+	}
 	right_type := c.expr(infix_expr.right)
 	infix_expr.right_type = right_type
 	right := c.table.get_type_symbol(right_type)
@@ -1709,6 +1712,9 @@ pub fn (c mut Checker) warn(s string, pos token.Position) {
 }
 
 pub fn (c mut Checker) error(message string, pos token.Position) {
+	if c.pref.is_verbose {
+		print_backtrace()
+	}
 	c.warn_or_error(message, pos, false)
 }
 

vlib/v/gen/cgen.v

@@ -126,15 +126,10 @@ pub fn cgen(files []ast.File, table &table.Table, pref &pref.Preferences) string
 	}
 	//
 	g.finish()
-	return g.hashes() +
-		'\n// V typedefs:\n' + g.typedefs.str() +
-		'\n// V typedefs2:\n' + g.typedefs2.str() +
-		'\n// V cheaders:\n' + g.cheaders.str() +
-		'\n// V includes:\n' + g.includes.str() +
-		'\n// V definitions:\n' + g.definitions.str() +
-		'\n// V gowrappers:\n' + g.gowrappers.str() +
-		'\n// V stringliterals:\n' + g.stringliterals.str() +
-		'\n// V out\n' + g.out.str()
+	return g.hashes() + '\n// V typedefs:\n' + g.typedefs.str() + '\n// V typedefs2:\n' + g.typedefs2.str() +
+		'\n// V cheaders:\n' + g.cheaders.str() + '\n// V includes:\n' + g.includes.str() + '\n// V definitions:\n' +
+		g.definitions.str() + '\n// V gowrappers:\n' + g.gowrappers.str() + '\n// V stringliterals:\n' +
+		g.stringliterals.str() + '\n// V out\n' + g.out.str()
 }
 
 pub fn (g Gen) hashes() string {
@@ -1211,6 +1206,10 @@ fn (g mut Gen) infix_expr(node ast.InfixExpr) {
 	// string + string, string == string etc
 	// g.infix_op = node.op
 	left_sym := g.table.get_type_symbol(node.left_type)
+	if node.op == .key_is {
+		g.is_expr(node)
+		return
+	}
 	right_sym := g.table.get_type_symbol(node.right_type)
 	if node.left_type == table.string_type_idx && node.op != .key_in && node.op != .not_in {
 		fn_name := match node.op {
@@ -2828,6 +2827,12 @@ fn (g mut Gen) go_stmt(node ast.GoStmt) {
 	}
 }
 
+fn (g mut Gen) is_expr(node ast.InfixExpr) {
+	g.expr(node.left)
+	g.write('.typ == ')
+	g.expr(node.right)
+}
+
 // already generated styp, reuse it
 fn (g mut Gen) gen_str_for_type(sym table.TypeSymbol, styp string) {
 	if sym.has_method('str') || styp in g.str_types {

vlib/v/parser/parser.v

@@ -21,7 +21,7 @@ mut:
 	peek_tok          token.Token
 	table             &table.Table
 	is_c              bool
-	is_js			  bool
+	is_js             bool
 	inside_if         bool
 	inside_for        bool
 	inside_fn         bool
@@ -39,6 +39,7 @@ mut:
 	inside_match      bool // to separate `match A { }` from `Struct{}`
 	inside_match_case bool // to separate `match_expr { }` from `Struct{}`
 	is_stmt_ident     bool // true while the beginning of a statement is an ident/selector
+	inside_is         bool // `is Type`, expecting type
 }
 
 // for tests
@@ -616,6 +617,11 @@ fn (p mut Parser) struct_init(short_syntax bool) ast.StructInit {
 
 pub fn (p mut Parser) name_expr() ast.Expr {
 	var node := ast.Expr{}
+	if p.inside_is {
+		return ast.Type{
+			typ: p.parse_type()
+		}
+	}
 	is_c := p.tok.lit == 'C'
 	is_js := p.tok.lit == 'JS'
 	var mod := ''
@@ -635,8 +641,8 @@ pub fn (p mut Parser) name_expr() ast.Expr {
 		return p.string_expr()
 	}
 	known_var := p.scope.known_var(p.tok.lit)
-	if p.peek_tok.kind == .dot && !known_var && (is_c || is_js || p.known_import(p.tok.lit) || p.mod.all_after('.') ==
-		p.tok.lit) {
+	if p.peek_tok.kind == .dot && !known_var && (is_c || is_js || p.known_import(p.tok.lit) ||
+		p.mod.all_after('.') == p.tok.lit) {
 		if is_c {
 			mod = 'C'
 		} else if is_js {
@@ -1044,7 +1050,11 @@ fn (p mut Parser) infix_expr(left ast.Expr) ast.Expr {
 	pos := p.tok.position()
 	p.next()
 	var right := ast.Expr{}
+	if op == .key_is {
+		p.inside_is = true
+	}
 	right = p.expr(precedence)
+	p.inside_is = false
 	var expr := ast.Expr{}
 	expr = ast.InfixExpr{
 		left: left
@@ -1511,7 +1521,7 @@ fn (p mut Parser) const_decl() ast.ConstDecl {
 	if p.tok.kind != .lpar {
 		p.error('consts must be grouped, e.g.\nconst (\n\ta = 1\n)')
 	}
-	p.next() // (
+	p.next()	// (
 	var fields := []ast.ConstField
 	for p.tok.kind != .rpar {
 		if p.tok.kind == .comment {

vlib/v/tests/mut_test.v

@@ -14,7 +14,7 @@ fn foo(b int, a mut []int) {
 }
 
 fn test_mut() {
-	mut numbers := [1, 2, 3]
+	var numbers := [1, 2, 3]
 	foo(7, mut numbers)
 	assert numbers.len == 3
 	// TODO bring back once << works with mutable args
@@ -23,15 +23,16 @@ fn test_mut() {
 	// assert numbers[3] == 4
 	println(numbers)
 	n := 1
-	mut b := &n
-	*b = 10
-	//mut b := mut a
-	//b = 10
+	var b := &n
+	//
+	(*b) = 10
+	// mut b := mut a
+	// b = 10
 }
 
 fn test_mut_2() {
 	zero := 0
-	mut b := B{}
+	var b := B{}
 	b.a << A{}
 	b.a[0].v = [9, 8, 7]
 	b.a[0].v << 6

vlib/v/tests/sum_type_test.v

@@ -0,0 +1,31 @@
+type Expr = IfExpr | IntegerLiteral
+
+struct IfExpr {
+	pos int
+}
+
+struct IntegerLiteral {
+	val string
+}
+
+fn handle(e Expr) string {
+	assert e is IntegerLiteral
+	if e is IntegerLiteral {
+		println('int')
+	}
+	match e {
+		IntegerLiteral {
+			return 'int'
+		}
+		IfExpr {
+			return 'if'
+		}
+	}
+	return ''
+}
+
+fn test_expr() {
+	expr := IntegerLiteral{'12'}
+	assert handle(expr) == 'int'
+	// assert expr is IntegerLiteral
+}

vlib/v/token/token.v

@@ -101,6 +101,7 @@ pub enum Kind {
 	key_import_const
 	key_in
 	key_interface
+	key_is
 	// key_it
 	key_match
 	key_module
@@ -246,6 +247,7 @@ fn build_token_str() []string {
 	s[Kind.key_select] = 'select'
 	s[Kind.key_none] = 'none'
 	s[Kind.key_offsetof] = '__offsetof'
+	s[Kind.key_is] = 'is'
 	s[Kind.key_var] = 'var'
 	return s
 }
@@ -385,7 +387,7 @@ pub fn (tok Token) precedence() int {
 		.left_shift_assign, .right_shift_assign, .mult_assign, .xor_assign {
 			return int(Precedence.assign)
 		}
-		.key_in, .not_in, .key_as {
+		.key_in, .not_in, .key_as, .key_is {
 			return int(Precedence.in_as)
 		}
 		.logical_or, .and {
@@ -425,7 +427,7 @@ 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, .not_in,
+	.key_as, .ge, .le, .logical_or, .xor, .not_in, .key_is,
 	//
 	.and, .dot, .pipe, .amp, .left_shift, .right_shift]
 }