v/vlib/compiler/expression.v

// Copyright (c) 2019-2020 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module compiler

fn (p mut Parser) bool_expression() string {
	//is_ret := p.prev_tok == .key_return
	start_ph := p.cgen.add_placeholder()
	mut expected := p.expected_type
	tok := p.tok
	typ := p.bterm()
	mut got_and := false // to catch `a && b || c` in one expression without ()
	mut got_or := false
	for p.tok == .and || p.tok == .logical_or {
		if p.tok == .and {
			got_and = true
			if got_or {
				p.error(and_or_error)
			}
		}
		if p.tok == .logical_or {
			got_or = true
			if got_and {
				p.error(and_or_error)
			}
		}
		if p.is_sql {
			if p.tok == .and {
				p.gen(' and ')
			}
			else if p.tok == .logical_or {
				p.gen(' or ')
			}
		}
		else {
			p.gen(' ${p.tok.str()} ')
		}
		p.check_space(p.tok)
		p.check_types(p.bterm(), typ)
		if typ != 'bool' {
			p.error('logical operators `&&` and `||` require booleans')
		}
	}
	if typ == '' {
		println('curline:')
		println(p.cgen.cur_line)
		println(tok.str())
		p.error('expr() returns empty type')
	}
	if p.inside_return_expr && p.expected_type.contains('_MulRet_') { //is_ret { // return a,b hack TODO
		expected = p.expected_type
	}
	// `window.widget = button`, widget is an interface
	if expected != typ && expected.ends_with('er') && expected.contains('I') {
		tt := typ.replace('*', '_ptr')
		/*
		if p.fileis('button') || p.fileis('textbox') {
			p.warn('exp="$expected" typ="$typ" tt="$tt"')
		}
		*/
		p.cgen.set_placeholder(start_ph,
		'($expected) { ._interface_idx = /* :) */ _${expected}_${tt}_index, ._object = ' )
		p.gen('}')
		//p.satisfies_interface(expected, typ, true)
	}
	// e.g. `return InfixExpr{}` in a function expecting `Expr`
	if expected != typ && expected in p.table.sum_types { // TODO perf
		//p.warn('SUM CAST exp=$expected typ=$typ p.exp=$p.expected_type')
		if typ in p.table.sum_types[expected] {
			p.cgen.set_placeholder(start_ph, '/*SUM TYPE CAST2*/ ($expected) { .obj = memdup( &($typ[]) { ')
			tt := typ.all_after('_') // TODO
			p.gen('}, sizeof($typ) ), .typ = SumType_${expected}_${tt} }')//${val}_type }')
		}
	}
	// `as` cast
	// TODO remove copypasta
	if p.tok == .key_as {
		return p.key_as(typ, start_ph)
	}
	return typ
}

fn (p mut Parser) key_as(typ string, start_ph int) string {
	p.fspace()
	p.next()
	p.fspace()
	cast_typ := p.get_type()
	if typ == cast_typ {
		p.error('casting `$typ` to `$cast_typ` is not needed')
	}
	if typ in p.table.sum_types {
		if !(cast_typ in  p.table.sum_types[typ]) {
			p.error('cannot cast `$typ` to `$cast_typ`. `$cast_typ` is not a variant of `$typ`')
		}
		p.cgen.set_placeholder(start_ph, '*($cast_typ*)')
		p.gen('.obj')
		// Make sure the sum type can be cast, otherwise throw a runtime error
		/*
		sum_type:= p.cgen.cur_line.all_after('*) (').replace('.obj', '.typ')

		n := cast_typ.all_after('__')
		p.cgen.insert_before('if (($sum_type != SumType_${typ}_$n) {
puts("runtime error: $p.file_name:$p.scanner.line_nr cannot cast sum type `$typ` to `$n`");
exit(1);
}
')
*/
	} else {
		p.error('`as` casts have been removed, use the old syntax: `Type(val)`')
	}
	return cast_typ
}

fn (p mut Parser) bterm() string {
	ph := p.cgen.add_placeholder()
	mut typ := p.expression()
	p.expected_type = typ
	is_str := typ == 'string' && !p.is_sql
	is_ustr := typ == 'ustring'
	base := p.base_type(typ)
	is_float := base[0] == `f` && (base in ['f64', 'f32']) && !(p.cur_fn.name in ['f64_abs', 'f32_abs']) && p.cur_fn.name != 'eq'
	is_array := typ.starts_with('array_')
	expr_type := base
	tok := p.tok
	/*
	if tok == .assign {
		p.error('no = ')
	}
	*/

	if tok in [.eq, .gt, .lt, .le, .ge, .ne] {
		// TODO: remove when array comparing is supported
		if is_array {
			p.error('array comparison is not supported yet')
		}
		p.fspace()
		// p.fgen(' ${p.tok.str()} ')
		if (is_float || is_str || is_ustr) && !p.is_js {
			p.gen(',')
		}
		else if p.is_sql && tok == .eq {
			p.gen('=')
		}
		else {
			p.gen(tok.str())
		}
		p.next()
		p.fspace()
		// `id == user.id` => `id == $1`, `user.id`
		if p.is_sql {
			p.sql_i++
			p.gen('$' + p.sql_i.str())
			p.cgen.start_cut()
			p.check_types(p.expression(), typ)
			sql_param := p.cgen.cut()
			p.sql_params << sql_param
			p.sql_types << typ
			// println('*** sql type: $typ | param: $sql_param')
		}
		else {
			p.check_types(p.expression(), typ)
		}
		typ = 'bool'
		if is_str && !p.is_js {
			// && !p.is_sql {
			p.gen(')')
			match tok {
				.eq {
					p.cgen.set_placeholder(ph, 'string_eq(')
				}
				.ne {
					p.cgen.set_placeholder(ph, 'string_ne(')
				}
				.le {
					p.cgen.set_placeholder(ph, 'string_le(')
				}
				.ge {
					p.cgen.set_placeholder(ph, 'string_ge(')
				}
				.gt {
					p.cgen.set_placeholder(ph, 'string_gt(')
				}
				.lt {
					p.cgen.set_placeholder(ph, 'string_lt(')
				}
				else {
				}}
		}
		if is_ustr {
			p.gen(')')
			match tok {
				.eq {
					p.cgen.set_placeholder(ph, 'ustring_eq(')
				}
				.ne {
					p.cgen.set_placeholder(ph, 'ustring_ne(')
				}
				.le {
					p.cgen.set_placeholder(ph, 'ustring_le(')
				}
				.ge {
					p.cgen.set_placeholder(ph, 'ustring_ge(')
				}
				.gt {
					p.cgen.set_placeholder(ph, 'ustring_gt(')
				}
				.lt {
					p.cgen.set_placeholder(ph, 'ustring_lt(')
				}
				else {
				}}
		}
		if is_float && p.cur_fn.name != 'f32_abs' && p.cur_fn.name != 'f64_abs' {
			p.gen(')')
			match tok {
				// NB: For more precision/stability, the == and != float
				// comparisons are done with V functions that use the epsilon
				// constants for the given type.
				// Everything else uses native comparisons (C macros) for speed.
				.eq {
					p.cgen.set_placeholder(ph, '${expr_type}_eq(')
				}
				.ne {
					p.cgen.set_placeholder(ph, '${expr_type}_ne(')
				}
				.le {
					p.cgen.set_placeholder(ph, 'macro_${expr_type}_le(')
				}
				.ge {
					p.cgen.set_placeholder(ph, 'macro_${expr_type}_ge(')
				}
				.gt {
					p.cgen.set_placeholder(ph, 'macro_${expr_type}_gt(')
				}
				.lt {
					p.cgen.set_placeholder(ph, 'macro_${expr_type}_lt(')
				}
				else {
				}}
		}
	}
	return typ
}

// also called on *, &, @, . (enum)
fn (p mut Parser) name_expr() string {
	p.has_immutable_field = false
	p.is_const_literal = false
	ph := p.cgen.add_placeholder()
	// amp
	ptr := p.tok == .amp
	deref := p.tok == .mul
	mut mul_nr := 0
	mut deref_nr := 0
	for {
		if p.tok == .amp {
			mul_nr++
		}
		else if p.tok == .mul {
			deref_nr++
		}
		else {
			break
		}
		p.next()
	}
	if p.tok == .lpar {
		p.gen('*'.repeat(deref_nr))
		p.gen('(')
		p.check(.lpar)
		mut temp_type := p.bool_expression()
		p.gen(')')
		p.check(.rpar)
		for _ in 0 .. deref_nr {
			temp_type = temp_type.replace_once('*', '')
		}
		return temp_type
	}
	mut name := p.lit
	// blank identifier (not var)
	if name == '_' {
		p.error('cannot use `_` as value')
	}
	// generic type check
	if name in p.generic_dispatch.inst.keys() {
		name = p.generic_dispatch.inst[name]
	}
	// Raw string (`s := r'hello \n ')
	if name == 'r' && p.peek() == .string&& p.prev_tok != .str_dollar {
		p.string_expr()
		return 'string'
	}
	// C string (a zero terminated one) C.func( c'hello' )
	if name == 'c' && p.peek() == .string&& p.prev_tok != .str_dollar {
		p.string_expr()
		return 'charptr'
	}
	// known_type := p.table.known_type(name)
	orig_name := name
	is_c := name == 'C' && p.peek() == .dot
	if is_c {
		p.check(.name)
		p.check(.dot)
		name = p.lit
		// C struct initialization
		if p.peek() == .lcbr && p.expected_type == '' {
			// not an expression
			if !p.table.known_type(name) {
				p.error('unknown C type `$name`, ' + 'define it with `struct C.$name { ... }`')
			}
			return p.get_struct_type(name, true, ptr)
		}
		if ptr && p.peek() == .lpar {
			peek2 := p.tokens[p.token_idx + 1]
			// `&C.Foo(0)` cast (replacing old `&C.Foo{!}`)
			if peek2.tok == .number && peek2.lit == '0' {
				p.cgen.insert_before('struct /*C.Foo(0)*/ ')
				p.gen('0')
				p.next()
				p.next()
				p.next()
				p.next()
				return name + '*'
			}
			// `&C.Foo(foo)` cast
			p.cast(name + '*')
			return name + '*'
		}
		// C function
		if p.peek() == .lpar {
			return p.get_c_func_type(name)
		}
		// C const (`C.GLFW_KEY_LEFT`)
		p.gen(name)
		p.next()
		return 'int'
	}
	// enum value? (`color == .green`)
	if p.tok == .dot {
		if p.table.known_type(p.expected_type) {
			p.check_enum_member_access()
			// println("found enum value: $p.expected_type")
			return p.expected_type
		}
		else {
			p.error('unknown enum: `$p.expected_type`')
		}
	}
	// Variable, checked before modules, so that module shadowing is allowed:
	// `gg = gg.newcontext(); gg.draw_rect(...)`
	if p.known_var_check_new_var(name) {
		return p.get_var_type(name, ptr, deref_nr)
	}
	// Module?
	if p.peek() == .dot && (name == p.mod || p.import_table.known_alias(name)) && !is_c {
		mut mod := name
		// must be aliased module
		if name != p.mod && p.import_table.known_alias(name) {
			p.import_table.register_used_import(name)
			mod = p.import_table.resolve_alias(name)
		}
		p.next()
		p.check(.dot)
		name = p.lit
		name = prepend_mod(mod_gen_name(mod), name)
	}
	// Unknown name, try prepending the module name to it
	// TODO perf
	else if !p.table.known_type(name) && !p.known_fn_in_mod(name) && !p.table.known_const(name) && !is_c {
		name = p.prepend_mod(name)
	}
	// re-check
	if p.known_var_check_new_var(name) {
		return p.get_var_type(name, ptr, deref_nr)
	}
	// if known_type || is_c_struct_init || (p.first_pass() && p.peek() == .lcbr) {
	// known type? int(4.5) or Color.green (enum)
	if p.table.known_type(name) {
		// cast expression: float(5), byte(0), (*int)(ptr) etc
		// if !is_c && ( p.peek() == .lpar || (deref && p.peek() == .rpar) ) {
		if p.peek() == .lpar || (deref && p.peek() == .rpar) {
			if deref {
				name += '*'.repeat(deref_nr)
			}
			else if ptr {
				name += '*'.repeat(mul_nr)
			}
			// p.gen('(')
			mut typ := name
			p.cast(typ)
			// p.gen(')')
			for p.tok == .dot {
				typ = p.dot(typ, ph)
			}
			return typ
		}
		// Color.green
		else if p.peek() == .dot {
			is_arr_start := p.prev_tok == .lsbr
			enum_type := p.table.find_type(name)
			if enum_type.cat != .enum_ {
				p.error('`$name` is not an enum')
			}
			p.next()
			p.check(.dot)
			val := p.lit
			if !enum_type.has_enum_val(val) {
				p.error('enum `$enum_type.name` does not have value `$val`')
			}
			if p.expected_type == enum_type.name && !is_arr_start {
				// `if color == .red` is enough
				// no need in `if color == Color.red`
				p.warn('`${enum_type.name}.$val` is unnecessary, use `.$val`')
			}
			// `expr := Expr.BoolExpr(true)` =>
			// `Expr expr = { .obj = true, .typ = BoolExpr_type };`
			if val[0].is_capital() {
				p.next()
				p.check(.lpar)
				//println('sum type $val name=$val')
				// Find a corresponding tuple variant
				// TODO slow, but this will be re-written anyway
				mut idx := 0
				for i, val_ in enum_type.enum_vals {
					//println('f $field.name')
					if val_ == val {
						idx = i
					}
				}
				q := p.table.tuple_variants[enum_type.name]
				//println(q)
				//println(q[idx])
				arg_type := q[idx]
				p.gen('($enum_type.name) { .obj = ($arg_type[]) { ')
				p.bool_expression()
				p.check(.rpar)
				p.gen('}, .typ = ${val}_type }')
				return enum_type.name
			}
			// println('enum val $val')
			p.gen(mod_gen_name(enum_type.mod) + '__' + enum_type.name + '_' + val) // `color = main__Color_green`
			p.next()
			return enum_type.name
		}
		// normal struct init (non-C)
		else if p.peek() == .lcbr || p.peek() == .lt {
			return p.get_struct_type(name, false, ptr)
		}
	}
	// Constant
	if p.table.known_const(name) {
		return p.get_const_type(name, ptr)
	}
	// TODO: V script? Try os module.
	// Function (not method, methods are handled in `.dot()`)
	mut f := p.table.find_fn_is_script(name, p.v_script) or {
		// First pass, the function can be defined later.
		if p.first_pass() {
			p.next()
			return 'unresolved'
		}
		// exhaused all options type,enum,const,mod,var,fn etc
		// so show undefined error (also checks typos)
		p.undefined_error(name, orig_name)
		return '' // panics
	}
	// no () after func, so func is an argument, just gen its name
	// TODO verify this and handle errors
	peek := p.peek()
	if peek != .lpar && peek != .lt {
		// Register anon fn type
		fn_typ := Type{
			name: f.typ_str() // 'fn (int, int) string'

			mod: p.mod
			func: f
		}
		p.table.register_type(fn_typ)
		p.gen(p.table.fn_gen_name(f))
		p.next()
		return f.typ_str() // 'void*'
	}
	// TODO bring back
	if f.typ == 'void' && !p.inside_if_expr {
		// p.error('`$f.name` used as value')
	}
	fn_call_ph := p.cgen.add_placeholder()
	// println('call to fn $f.name of type $f.typ')
	// TODO replace the following dirty hacks (needs ptr access to fn table)
	new_f := f
	p.fn_call(mut new_f, 0, '', '')
	if f.is_generic {
		_ = p.table.find_fn(f.name) or {
			return ''
		}
		// println('after call of generic instance $new_f.name(${new_f.str_args(p.table)}) $new_f.typ')
		// println('	from $f2.name(${f2.str_args(p.table)}) $f2.typ : $f2.type_inst')
	}
	f = new_f
	// optional function call `function() or {}`, no return assignment
	is_or_else := p.tok == .key_orelse
	if p.tok == .question {
		// `files := os.ls('.')?`
		return p.gen_handle_question_suffix(f, fn_call_ph)
	}
	else if !p.is_var_decl && is_or_else {
		f.typ = p.gen_handle_option_or_else(f.typ, '', fn_call_ph)
	}
	else if !p.is_var_decl && !is_or_else && !p.inside_return_expr && f.typ.starts_with('Option_') {
		opt_type := f.typ[7..].replace('ptr_', '&')
		p.error('unhandled option type: `?$opt_type`')
	}
	// dot after a function call: `get_user().age`
	if p.tok == .dot {
		mut typ := ''
		for p.tok == .dot {
			// println('dot #$dc')
			typ = p.dot(f.typ, ph)
		}
		return typ
	}
	// p.log('end of name_expr')
	if f.typ.ends_with('*') {
		p.is_alloc = true
	}
	return f.typ
}

// returns resulting type
fn (p mut Parser) expression() string {
	p.is_const_literal = true
	// if p.scanner.file_path.contains('test_test') {
	// println('expression() pass=$p.pass tok=')
	// p.print_tok()
	// }
	ph := p.cgen.add_placeholder()
	typ := p.indot_expr()
	is_str := typ == 'string'
	is_ustr := typ == 'ustring'
	// `a << b` ==> `array_push(&a, b)`
	if p.tok == .left_shift {
		if typ.contains('array_') {
			// Can't pass integer literal, because push requires a void*
			// a << 7 => int tmp = 7; array_push(&a, &tmp);
			// _PUSH(&a, expression(), tmp, string)
			tmp := p.get_tmp()
			tmp_typ := parse_pointer(typ[6..]) // skip "array_"
			//p.warn('arr typ $tmp_typ')
			p.expected_type = tmp_typ
			//println('set expr to $tmp_typ')
			p.check_space(.left_shift)
			// Get the value we are pushing
			p.gen(', (')
			// Immutable? Can we push?
			if !p.expr_var.is_mut && !p.pref.translated {
				p.error("`$p.expr_var.name` is immutable (can\'t <<)")
			}
			if p.expr_var.is_arg && p.expr_var.typ.starts_with('array_') {
				p.error("for now it's not possible to append an element to " + 'a mutable array argument `$p.expr_var.name`')
			}
			if !p.expr_var.is_changed {
				p.mark_var_changed(p.expr_var)
			}
			p.gen('/*typ = $typ   tmp_typ=$tmp_typ*/')
			ph_clone := p.cgen.add_placeholder()
			expr_type := p.bool_expression()
			// Need to clone the string when appending it to an array?
			if p.pref.autofree && typ == 'array_string' && expr_type == 'string' {
				p.cgen.set_placeholder(ph_clone, 'string_clone(')
				p.gen(')')
			}
			p.gen_array_push(ph, typ, expr_type, tmp, tmp_typ)
			return 'void'
		}
		else {
			if !is_integer_type(typ) {
				t := p.table.find_type(typ)
				if t.cat != .enum_ {
					p.error('cannot use shift operator on non-integer type `$typ`')
				}
			}
			p.next()
			p.gen(' << ')
			p.check_types(p.expression(), 'integer')
			return typ
		}
	}
	if p.tok == .righ_shift {
		if !is_integer_type(typ) {
			t := p.table.find_type(typ)
			if t.cat != .enum_ {
				p.error('cannot use shift operator on non-integer type `$typ`')
			}
		}
		p.next()
		p.gen(' >> ')
		p.check_types(p.expression(), 'integer')
		return typ
	}
	// + - | ^
	for p.tok in [.plus, .minus, .pipe, .amp, .xor] {
		tok_op := p.tok
		if typ == 'bool' {
			p.error('operator ${p.tok.str()} not defined on bool ')
		}
		is_num := typ.contains('*') || is_number_type(typ) || is_number_type(p.base_type(typ))
		p.check_space(p.tok)
		if is_str && tok_op == .plus && !p.is_js {
			p.is_alloc = true
			p.cgen.set_placeholder(ph, 'string_add(')
			p.gen(',')
		}
		else if is_ustr && tok_op == .plus {
			p.cgen.set_placeholder(ph, 'ustring_add(')
			p.gen(',')
		}
		// 3 + 4
		else if is_num || p.is_js {
			if typ == 'void*' {
				// Msvc errors on void* pointer arithmatic
				// ... So cast to byte* and then do the add
				p.cgen.set_placeholder(ph, '(byte*)')
			}
			else if typ.contains('*') {
				p.cgen.set_placeholder(ph, '($typ)')
			}
			p.gen(tok_op.str())
		}
		// Vec + Vec
		else {
			if p.pref.translated {
				p.gen(tok_op.str() + ' /*doom hack*/') // TODO hack to fix DOOM's angle_t
			}
			else {
				p.gen(',')
			}
		}
		if is_str && tok_op != .plus {
			p.error('strings only support `+` operator')
		}
		expr_type := p.term()
		open := tok_op == .amp && p.tok in [.eq, .ne] // force precedence `(a & b) == c`  //false
		if tok_op in [.pipe, .amp, .xor] {
			if !(is_integer_type(expr_type) && is_integer_type(typ)) {
				p.error('operator ${tok_op.str()} is defined only on integer types')
			}
			// open = true
		}
		if open {
			p.cgen.set_placeholder(ph, '(')
		}
		p.check_types(expr_type, typ)
		if (is_str || is_ustr) && tok_op == .plus && !p.is_js {
			p.gen(')')
		}
		if open {
			p.gen(')')
		}
		// Make sure operators are used with correct types
		if !p.pref.translated && !is_str && !is_ustr && !is_num {
			T := p.table.find_type(typ)
			if tok_op == .plus {
				p.handle_operator('+', typ, 'op_plus', ph, T)
			}
			else if tok_op == .minus {
				p.handle_operator('-', typ, 'op_minus', ph, T)
			}
		}
	}
	// `as` cast
	// TODO remove copypasta
	if p.tok == .key_as {
		return p.key_as(typ, ph)
	}
	return typ
}

fn (p mut Parser) handle_operator(op string, typ string,cpostfix string, ph int, tt &Type) {
	if tt.has_method(op) {
		p.cgen.set_placeholder(ph, '${typ}_${cpostfix}(')
		p.gen(')')
	}
	else if typ != 'unresolved' {
		p.error('operator $op not defined on `$typ`')
	}
}

fn (p mut Parser) term() string {
	line_nr := p.scanner.line_nr
	// if p.fileis('fn_test') {
	// println('\nterm() $line_nr')
	// }
	ph := p.cgen.add_placeholder()
	typ := p.unary()
	// if p.fileis('fn_test') {
	// println('2: $line_nr')
	// }
	// `*` on a newline? Can't be multiplication, only dereference
	if p.tok == .mul && line_nr != p.scanner.line_nr {
		return typ
	}
	for p.tok in [.mul, .div, .mod] {
		tok := p.tok
		is_mul := tok == .mul
		is_div := tok == .div
		is_mod := tok == .mod
		p.fspace()
		p.next()
		p.gen(tok.str()) // + ' /*op2*/ ')
		oph := p.cgen.add_placeholder()
		p.fspace()
		if (is_div || is_mod) && p.tok == .number && p.lit == '0' {
			p.error('division or modulo by zero')
		}
		expr_type := p.unary()
		if (is_mul || is_div) && expr_type == 'string' {
			p.error('operator ${tok.str()} cannot be used on strings')
		}
		if !is_primitive_type(expr_type) && expr_type == typ {
			p.check_types(expr_type, typ)
			T := p.table.find_type(typ)
			// NB: oph is a char index just after the OP
			before_oph := p.cgen.cur_line[..oph - 1]
			after_oph := p.cgen.cur_line[oph..]
			p.cgen.cur_line = before_oph + ',' + after_oph
			match tok {
				.mul {
					p.handle_operator('*', typ, 'op_mul', ph, T)
				}
				.div {
					p.handle_operator('/', typ, 'op_div', ph, T)
				}
				.mod {
					p.handle_operator('%', typ, 'op_mod', ph, T)
				}
				else {
				}}
			continue
		}
		if is_mod {
			if !(is_integer_type(expr_type) && is_integer_type(typ)) {
				p.error('operator `mod` requires integer types')
			}
		}
		else {
			p.check_types(expr_type, typ)
		}
	}
	return typ
}

fn (p mut Parser) unary() string {
	mut typ := ''
	tok := p.tok
	match tok {
		.not {
			p.gen('!')
			p.check(.not)
			// typ should be bool type
			typ = p.indot_expr()
			if typ != 'bool' {
				p.error('operator ! requires bool type, not `$typ`')
			}
		}
		.bit_not {
			p.gen('~')
			p.check(.bit_not)
			typ = p.bool_expression()
		}
		else {
			typ = p.factor()
		}}
	return typ
}

fn (p mut Parser) factor() string {
	mut typ := ''
	tok := p.tok
	match tok {
		.key_none {
			if !p.expected_type.starts_with('Option_') {
				p.error('need "$p.expected_type" got none')
			}
			p.gen('opt_none()')
			p.check(.key_none)
			return p.expected_type
		}
		.number {
			// Check if float (`1.0`, `1e+3`) but not if is hexa (e.g. 0xEE contains `E` but is not float)
			typ = if (p.lit.contains('.') || p.lit.contains('e') || p.lit.contains('E')) && !(p.lit[..2] in ['0x', '0X']) { 'f64' } else { 'int' }
			if p.expected_type != '' && !is_valid_int_const(p.lit, p.expected_type) {
				p.error('constant `$p.lit` overflows `$p.expected_type`')
			}
			p.gen(p.lit)
		}
		.minus {
			p.gen('-')
			p.next()
			return p.factor()
			// Variable
		}
		.key_sizeof {
			p.gen('sizeof(')
			// p.fgen('sizeof(')
			p.next()
			p.check(.lpar)
			mut sizeof_typ := p.get_type()
			p.check(.rpar)
			p.gen('$sizeof_typ)')
			// p.fgen('$sizeof_typ)')
			return 'int'
		}
		.key_typeof {
			p.next()
			p.check(.lpar)
			p.cgen.nogen = true
			vname := if p.tok == .name && p.peek() == .rpar { p.lit } else { '' }
			type_of_var := p.expression()
			p.cgen.nogen = false
			p.check(.rpar)
			is_sum_type := type_of_var in p.table.sum_types
			if is_sum_type && vname.len > 0 {
				// TODO: make this work for arbitrary sumtype expressions, not just simple vars
				// NB: __SumTypeNames__[xxx][0] is the name of the sumtype itself;
				// idx>0 are the names of the sumtype children
				p.gen('tos3(__SumTypeNames__${type_of_var}[${vname}.typ])')
			}else{
				p.gen('tos3("$type_of_var")')
			}
			return 'string'
		}
		.key_nameof {
			p.next()
			p.check(.lpar)
			mut nameof_typ := p.get_type()
			p.check(.rpar)
			p.gen('tos3("$nameof_typ")')
			return 'string'
		}
		.key_offsetof {
			p.next()
			p.check(.lpar)
			offsetof_typ := p.get_type()
			p.check(.comma)
			member := p.check_name()
			p.check(.rpar)
			p.gen('__offsetof($offsetof_typ, $member)')
			return 'int'
		}
		.amp, .dot, .mul {
			// (dot is for enum vals: `.green`)
			return p.name_expr()
		}
		.name {
			// map[string]int
			if p.lit == 'map' && p.peek() == .lsbr {
				return p.map_init()
			}
			if p.lit == 'json' && p.peek() == .dot {
				if !('json' in p.table.imports) {
					p.error('undefined: `json`, use `import json`')
				}
				p.import_table.register_used_import('json')
				return p.js_decode()
			}
			// if p.fileis('orm_test') {
			// println('ORM name: $p.lit')
			// }
			typ = p.name_expr()
			return typ
		}
		/*
	.key_default {
		p.next()
		p.next()
		name := p.check_name()
		if name != 'T' {
			p.error('default needs T')
		}
		p.gen('default(T)')
		p.next()
		return 'T'
	}
	*/

		.lpar {
			// p.gen('(/*lpar*/')
			p.gen('(')
			p.check(.lpar)
			typ = p.bool_expression()
			// Hack. If this `)` referes to a ptr cast `(*int__)__`, it was already checked
			// TODO: fix parser so that it doesn't think it's a par expression when it sees `(` in
			// __(__*int)(
			if !p.ptr_cast {
				p.check(.rpar)
			}
			p.ptr_cast = false
			p.gen(')')
			return typ
		}
		.chartoken {
			p.char_expr()
			typ = 'byte'
			return typ
		}
		.string{
			p.string_expr()
			typ = 'string'
			return typ
		}
		.key_false {
			typ = 'bool'
			p.gen('0')
		}
		.key_true {
			typ = 'bool'
			p.gen('1')
		}
		.lsbr {
			// `[1,2,3]` or `[]` or `[20]byte`
			// TODO have to return because arrayInit does next()
			// everything should do next()
			return p.array_init()
		}
		.lcbr {
			// `m := { 'one': 1 }`
			if p.peek() == .string{
				return p.map_init()
			}
			peek2 := p.tokens[p.token_idx + 1]
			if p.peek() == .rcbr || (p.peek() == .name && peek2.tok == .colon) {
				return p.struct_init(p.expected_type)
			}
			// { user | name :'new name' }
			return p.assoc()
		}
		.key_if {
			typ = p.if_statement(true, 0)
			return typ
		}
		.key_match {
			typ = p.match_statement(true)
			return typ
		}
		else {
			if p.pref.verbosity.is_higher_or_equal(.level_three) {
				next := p.peek()
				println('prev=${p.prev_tok.str()}')
				println('next=${next.str()}')
			}
			p.error('unexpected token: `${p.tok.str()}`')
		}}
	p.next() // TODO everything should next()
	return typ
}

// { user | name: 'new name' }