all: add builtin channel type `chan elem_type` (#6126)

vlib/sync/channel_array_mut_test.v

@@ -0,0 +1,36 @@
+import sync
+
+const (
+	num_iterations = 10000
+)
+
+struct St {
+mut:
+	n int
+}
+
+// this function gets an array of channels for `St` references
+fn do_rec_calc_send(chs []chan mut St) {
+	mut s := St{}
+	for {
+		if !(&sync.Channel(chs[0])).pop(&s) {
+			break
+		}
+		s.n++
+		(&sync.Channel(chs[1])).push(&s)
+	}
+}
+
+fn test_channel_array_mut() {
+	mut chs := [chan mut St{cap: 1}, chan mut St{}]
+	go do_rec_calc_send(chs)
+	mut t := St{
+		n: 100
+	}
+	for _ in 0 .. num_iterations {
+		(&sync.Channel(chs[0])).push(&t)
+		(&sync.Channel(chs[1])).pop(&t)
+	}
+	(&sync.Channel(chs[0])).close()
+	assert t.n == 100 + num_iterations
+}

vlib/sync/channel_select_2_test.v

@@ -0,0 +1,76 @@
+import sync
+
+fn do_rec_i64(ch chan i64) {
+	mut sum := i64(0)
+	for _ in 0 .. 300 {
+		mut a := i64(0)
+		(&sync.Channel(ch)).pop(&a)
+		sum += a
+	}
+	assert sum == 300 * (300 - 1) / 2
+}
+
+fn do_send_int(ch chan int) {
+	for i in 0 .. 300 {
+		(&sync.Channel(ch)).push(&i)
+	}
+}
+
+fn do_send_byte(ch chan byte) {
+	for i in 0 .. 300 {
+		ii := byte(i)
+		(&sync.Channel(ch)).push(&ii)
+	}
+}
+
+fn do_send_i64(mut ch sync.Channel) {
+	for i in 0 .. 300 {
+		ii := i64(i)
+		ch.push(&ii)
+	}
+}
+
+fn test_select() {
+	chi := chan int{}
+	mut chl := sync.new_channel<i64>(1)
+	chb := chan byte{cap: 10}
+	recch := chan i64{cap: 0}
+	go do_rec_i64(recch)
+	go do_send_int(chi)
+	go do_send_byte(chb)
+	go do_send_i64(mut chl)
+	mut channels := [&sync.Channel(chi), &sync.Channel(recch), chl, &sync.Channel(chb)]
+	directions := [sync.Direction.pop, .push, .pop, .pop]
+	mut sum := i64(0)
+	mut rl := i64(0)
+	mut ri := int(0)
+	mut rb := byte(0)
+	mut sl := i64(0)
+	mut objs := [voidptr(&ri), &sl, &rl, &rb]
+	for _ in 0 .. 1200 {
+		idx := sync.channel_select(mut channels, directions, mut objs, -1)
+		match idx {
+			0 {
+				sum += ri
+			}
+			1 {
+				sl++
+			}
+			2 {
+				sum += rl
+			}
+			3 {
+				sum += rb
+			}
+			else {
+				println('got $idx (timeout)')
+			}
+		}
+	}
+	// Use Gauß' formula for the first 2 contributions
+	expected_sum :=  2 * (300 * (300 - 1) / 2) +
+		// the 3rd contribution is `byte` and must be seen modulo 256
+		256 * (256 - 1) / 2 +
+		44 * (44 - 1) / 2
+	assert sum == expected_sum
+}

vlib/sync/channels.v

@@ -111,6 +111,10 @@ pub:
 
 pub fn new_channel<T>(n u32) &Channel {
 	st := sizeof(T)
+	return new_channel_st(n, st)
+}
+
+fn new_channel_st(n u32, st u32) &Channel {
 	return &Channel{
 		writesem: new_semaphore_init(if n > 0 { n + 1 } else { 1 })
 		readsem:  new_semaphore_init(if n > 0 { u32(0) } else { 1 })

vlib/v/ast/ast.v

@@ -10,7 +10,7 @@ import v.errors
 pub type TypeDecl = AliasTypeDecl | FnTypeDecl | SumTypeDecl
 
 pub type Expr = AnonFn | ArrayInit | AsCast | Assoc | BoolLiteral | CallExpr | CastExpr |
-	CharLiteral | Comment | ComptimeCall | ConcatExpr | EnumVal | FloatLiteral | Ident | IfExpr |
+	CharLiteral | ChanInit | Comment | ComptimeCall | ConcatExpr | EnumVal | FloatLiteral | Ident | IfExpr |
 	IfGuardExpr | IndexExpr | InfixExpr | IntegerLiteral | Likely | LockExpr | MapInit | MatchExpr |
 	None | OrExpr | ParExpr | PostfixExpr | PrefixExpr | RangeExpr | SelectorExpr | SizeOf |
 	SqlExpr | StringInterLiteral | StringLiteral | StructInit | Type | TypeOf | UnsafeExpr
@@ -751,6 +751,16 @@ pub mut:
 	typ             table.Type
 }
 
+pub struct ChanInit {
+pub:
+	pos        token.Position
+	cap_expr   Expr
+	has_cap    bool
+pub mut:
+	typ        table.Type
+	elem_type  table.Type
+}
+
 pub struct MapInit {
 pub:
 	pos        token.Position

vlib/v/checker/checker.v

@@ -2345,6 +2345,9 @@ pub fn (mut c Checker) expr(node ast.Expr) table.Type {
 		ast.CallExpr {
 			return c.call_expr(mut node)
 		}
+		ast.ChanInit {
+			return c.chan_init(mut node)
+		}
 		ast.CharLiteral {
 			return table.byte_type
 		}
@@ -3198,6 +3201,17 @@ pub fn (mut c Checker) enum_val(mut node ast.EnumVal) table.Type {
 	return typ
 }
 
+pub fn (mut c Checker) chan_init(mut node ast.ChanInit) table.Type {
+	if node.typ != 0 {
+		info := c.table.get_type_symbol(node.typ).chan_info()
+		node.elem_type = info.elem_type
+		return node.typ
+	} else {
+		c.error('`chan` of unknown type', node.pos)
+		return node.typ
+	}
+}
+
 pub fn (mut c Checker) map_init(mut node ast.MapInit) table.Type {
 	// `x ;= map[string]string` - set in parser
 	if node.typ != 0 {

vlib/v/fmt/fmt.v

@@ -799,6 +799,16 @@ pub fn (mut f Fmt) expr(node ast.Expr) {
 		ast.CallExpr {
 			f.call_expr(node)
 		}
+		ast.ChanInit {
+			f.write('chan[')
+			f.write(f.type_to_str(node.elem_type))
+			f.write(']{')
+			if node.has_cap {
+				f.write('cap: ')
+				f.expr(node.cap_expr)
+			}
+			f.write('}')
+		}
 		ast.CharLiteral {
 			f.write('`$node.val`')
 		}

vlib/v/gen/cgen.v

@@ -497,6 +497,10 @@ typedef struct {
 			.interface_ {
 				g.type_definitions.writeln('typedef _Interface ${c_name(typ.name)};')
 			}
+			.chan {
+				styp := util.no_dots(typ.name)
+				g.type_definitions.writeln('typedef chan $styp;')
+			}
 			.map {
 				styp := util.no_dots(typ.name)
 				g.type_definitions.writeln('typedef map $styp;')
@@ -1787,6 +1791,18 @@ fn (mut g Gen) expr(node ast.Expr) {
 				g.write('))')
 			}
 		}
+		ast.ChanInit {
+			elem_typ_str := g.typ(node.elem_type)
+			g.write('sync__new_channel_st(')
+			if node.has_cap {
+				g.expr(node.cap_expr)
+			} else {
+				g.write('0')
+			}
+			g.write(', sizeof(')
+			g.write(elem_typ_str)
+			g.write('))')
+		}
 		ast.CharLiteral {
 			g.write("'$node.val'")
 		}

vlib/v/gen/cheaders.v

@@ -415,6 +415,8 @@ typedef map map_string;
 typedef byte array_fixed_byte_300 [300];
 typedef byte array_fixed_byte_400 [400];
 
+typedef struct sync__Channel* chan;
+
 #ifndef __cplusplus
 	#ifndef bool
 		typedef int bool;

vlib/v/gen/js/js.v

@@ -232,6 +232,9 @@ pub fn (mut g JsGen) typ(t table.Type) string {
 			info := sym.info as table.ArrayFixed
 			styp = g.typ(info.elem_type) + '[]'
 		}
+		.chan {
+			styp = 'chan'
+		}
 		// 'map[string]int' => 'Map<string, number>'
 		.map {
 			info := sym.info as table.Map
@@ -533,6 +536,9 @@ fn (mut g JsGen) expr(node ast.Expr) {
 		ast.CallExpr {
 			g.gen_call_expr(node)
 		}
+		ast.ChanInit {
+			// TODO
+		}
 		ast.CastExpr {
 			// JS has no types, so no need to cast
 			// Just write the expression inside

vlib/v/parser/parse_type.v

@@ -51,6 +51,13 @@ pub fn (mut p Parser) parse_map_type() table.Type {
 	return table.new_type(idx)
 }
 
+pub fn (mut p Parser) parse_chan_type() table.Type {
+	p.next()
+	elem_type := p.parse_type()
+	idx := p.table.find_or_register_chan(elem_type)
+	return table.new_type(idx)
+}
+
 pub fn (mut p Parser) parse_multi_return_type() table.Type {
 	p.check(.lpar)
 	mut mr_types := []table.Type{}
@@ -211,6 +218,9 @@ pub fn (mut p Parser) parse_any_type(language table.Language, is_ptr, check_dot
 			if name == 'map' {
 				return p.parse_map_type()
 			}
+			if name == 'chan' {
+				return p.parse_chan_type()
+			}
 			defer {
 				p.next()
 			}

vlib/v/parser/parser.v

@@ -958,6 +958,47 @@ pub fn (mut p Parser) name_expr() ast.Expr {
 			typ: map_type
 		}
 	}
+	// `chan typ{...}`
+	if p.tok.lit == 'chan' {
+		first_pos := p.tok.position()
+		mut last_pos := p.tok.position()
+		chan_type := p.parse_chan_type()
+		mut has_cap := false
+		mut cap_expr := ast.Expr{}
+		p.check(.lcbr)
+		if p.tok.kind == .rcbr {
+			last_pos = p.tok.position()
+			p.next()
+		} else {
+			key := p.check_name()
+			p.check(.colon)
+			match key {
+				'cap' {
+					has_cap = true
+					cap_expr = p.expr(0)
+				}
+				'len', 'init' {
+					p.error('`$key` cannot be initialized for `chan`. Did you mean `cap`?')
+				}
+				else {
+					p.error('wrong field `$key`, expecting `cap`')
+				}
+			}
+			last_pos = p.tok.position()
+			p.check(.rcbr)
+		}
+		pos := token.Position{
+			line_nr: first_pos.line_nr
+			pos: first_pos.pos
+			len: last_pos.pos - first_pos.pos + last_pos.len
+		}
+		return ast.ChanInit{
+			pos: pos
+			has_cap: has_cap
+			cap_expr: cap_expr
+			typ: chan_type
+		}
+	}
 	// Raw string (`s := r'hello \n ')
 	if p.tok.lit in ['r', 'c', 'js'] && p.peek_tok.kind == .string && !p.inside_str_interp {
 		return p.string_expr()

vlib/v/table/atypes.v

@@ -15,7 +15,7 @@ import strings
 
 pub type Type int
 
-pub type TypeInfo = Alias | Array | ArrayFixed | Enum | FnType | GenericStructInst | Interface |
+pub type TypeInfo = Alias | Array | ArrayFixed | Chan | Enum | FnType | GenericStructInst | Interface |
 	Map | MultiReturn | Struct | SumType
 
 pub enum Language {
@@ -253,10 +253,11 @@ pub const (
 	ustring_type_idx = 19
 	array_type_idx   = 20
 	map_type_idx     = 21
-	any_type_idx     = 22
+	chan_type_idx    = 22
+	any_type_idx     = 23
 	// t_type_idx       = 23
-	any_flt_type_idx = 23
+	any_flt_type_idx = 24
-	any_int_type_idx = 24
+	any_int_type_idx = 25
 )
 
 pub const (
@@ -293,6 +294,7 @@ pub const (
 	ustring_type = new_type(ustring_type_idx)
 	array_type   = new_type(array_type_idx)
 	map_type     = new_type(map_type_idx)
+	chan_type    = new_type(chan_type_idx)
 	any_type     = new_type(any_type_idx)
 	// t_type       = new_type(t_type_idx)
 	any_flt_type = new_type(any_flt_type_idx)
@@ -302,7 +304,7 @@ pub const (
 pub const (
 	builtin_type_names = ['void', 'voidptr', 'charptr', 'byteptr', 'i8', 'i16', 'int', 'i64', 'u16',
 		'u32', 'u64', 'any_int', 'f32', 'f64', 'any_float', 'string', 'ustring', 'char', 'byte', 'bool',
-		'none', 'array', 'array_fixed', 'map', 'any', 'struct', 'mapnode', 'size_t']
+		'none', 'array', 'array_fixed', 'map', 'chan', 'any', 'struct', 'mapnode', 'size_t']
 )
 
 pub struct MultiReturn {
@@ -342,6 +344,7 @@ pub enum Kind {
 	array
 	array_fixed
 	map
+	chan
 	any
 	struct_
 	generic_struct_inst
@@ -391,6 +394,14 @@ pub fn (t &TypeSymbol) array_fixed_info() ArrayFixed {
 	}
 }
 
+[inline]
+pub fn (t &TypeSymbol) chan_info() Chan {
+	match t.info {
+		Chan { return *it }
+		else { panic('TypeSymbol.chan_info(): no chan info for type: $t.name') }
+	}
+}
+
 [inline]
 pub fn (t &TypeSymbol) map_info() Map {
 	match t.info {
@@ -524,6 +535,11 @@ pub fn (mut t Table) register_builtin_type_symbols() {
 		name: 'map'
 		mod: 'builtin'
 	})
+	t.register_type_symbol({
+		kind: .chan
+		name: 'chan'
+		mod: 'builtin'
+	})
 	t.register_type_symbol({
 		kind: .any
 		name: 'any'
@@ -616,6 +632,7 @@ pub fn (k Kind) str() string {
 		.array { 'array' }
 		.array_fixed { 'array_fixed' }
 		.map { 'map' }
+		.chan { 'chan' }
 		.multi_return { 'multi_return' }
 		.sum_type { 'sum_type' }
 		.alias { 'alias' }
@@ -708,6 +725,11 @@ pub mut:
 	elem_type Type
 }
 
+pub struct Chan {
+pub mut:
+	elem_type   Type
+}
+
 pub struct Map {
 pub mut:
 	key_type   Type

vlib/v/table/table.v

@@ -320,6 +320,13 @@ pub fn (t &Table) array_fixed_name(elem_type Type, size, nr_dims int) string {
 	}
 }
 
+[inline]
+pub fn (t &Table) chan_name(elem_type Type) string {
+	elem_type_sym := t.get_type_symbol(elem_type)
+	suffix := if elem_type.is_ptr() { '_ptr' } else { '' }
+	return 'chan_$elem_type_sym.name' + suffix
+}
+
 [inline]
 pub fn (t &Table) map_name(key_type, value_type Type) string {
 	key_type_sym := t.get_type_symbol(key_type)
@@ -329,6 +336,25 @@ pub fn (t &Table) map_name(key_type, value_type Type) string {
 	// return 'map_${value_type_sym.name}' + suffix
 }
 
+pub fn (mut t Table) find_or_register_chan(elem_type Type) int {
+	name := t.chan_name(elem_type)
+	// existing
+	existing_idx := t.type_idxs[name]
+	if existing_idx > 0 {
+		return existing_idx
+	}
+	// register
+	chan_typ := TypeSymbol{
+		parent_idx: chan_type_idx
+		kind: .chan
+		name: name
+		info: Chan{
+			elem_type: elem_type
+		}
+	}
+	return t.register_type_symbol(chan_typ)
+}
+
 pub fn (mut t Table) find_or_register_map(key_type, value_type Type) int {
 	name := t.map_name(key_type, value_type)
 	// existing