v/vlib/compiler/for.v

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// Copyright (c) 2019 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) for_st() {
p.check(.key_for)
p.fgen(' ')
p.for_expr_cnt++
next_tok := p.peek()
//debug := p.scanner.file_path.contains('r_draw')
p.open_scope()
if p.tok == .lcbr {
// Infinite loop
p.gen('while (1) {')
}
else if p.tok == .key_mut {
p.error('`mut` is not required in for loops')
}
// for i := 0; i < 10; i++ {
else if next_tok == .decl_assign || next_tok == .assign || p.tok == .semicolon {
p.genln('for (')
if next_tok == .decl_assign {
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p.check_not_reserved()
p.var_decl()
}
else if p.tok != .semicolon {
// allow `for ;; i++ {`
// Allow `for i = 0; i < ...`
p.statement(false)
}
p.check(.semicolon)
p.gen(' ; ')
p.fgen(' ')
if p.tok != .semicolon {
p.bool_expression()
}
p.check(.semicolon)
p.gen(' ; ')
p.fgen(' ')
if p.tok != .lcbr {
p.statement(false)
}
p.genln(') { ')
}
// for i, val in array
else if p.peek() == .comma {
/*
`for i, val in array {`
==>
```
array_int tmp = array;
for (int i = 0; i < tmp.len; i++) {
int val = tmp[i];
```
*/
i := p.check_name()
p.check(.comma)
val := p.check_name()
if i == '_' && val == '_' {
p.error('no new variables on the left side of `in`')
}
p.fgen(' ')
p.check(.key_in)
p.fgen(' ')
tmp := p.get_tmp()
p.cgen.start_tmp()
mut typ := p.bool_expression()
is_arr := typ.starts_with('array_')
is_map := typ.starts_with('map_')
is_str := typ == 'string'
is_variadic_arg := typ.starts_with('varg_')
if !is_arr && !is_str && !is_map && !is_variadic_arg {
p.error('cannot range over type `$typ`')
}
expr := p.cgen.end_tmp()
if !is_variadic_arg {
if p.is_js {
p.genln('var $tmp = $expr;')
} else {
p.genln('$typ $tmp = $expr;')
}
}
// typ = strings.Replace(typ, "_ptr", "*", -1)
mut i_var_type := 'int'
if is_variadic_arg {
typ = typ[5..]
p.gen_for_varg_header(i, expr, typ, val)
}
else if is_arr {
typ = typ[6..]
p.gen_for_header(i, tmp, typ, val)
}
else if is_map {
i_var_type = 'string'
typ = typ[4..]
p.gen_for_map_header(i, tmp, typ, val, typ)
}
else if is_str {
typ = 'byte'
p.gen_for_str_header(i, tmp, typ, val)
}
// Register temp vars
if i != '_' {
p.register_var(Var {
name: i
typ: i_var_type
is_mut: true
is_changed: true
})
}
if val != '_' {
p.register_var(Var {
name: val
typ: typ
ptr: typ.contains('*')
})
}
}
// `for val in vals`
else if p.peek() == .key_in {
val := p.check_name()
p.fgen(' ')
p.check(.key_in)
p.fspace()
tmp := p.get_tmp()
p.cgen.start_tmp()
mut typ := p.bool_expression()
expr := p.cgen.end_tmp()
is_range := p.tok == .dotdot
is_variadic_arg := typ.starts_with('varg_')
mut range_end := ''
if is_range {
p.check_types(typ, 'int')
p.check_space(.dotdot)
p.cgen.start_tmp()
p.check_types(p.bool_expression(), 'int')
range_end = p.cgen.end_tmp()
}
is_arr := typ.contains('array')
is_str := typ == 'string'
if !is_arr && !is_str && !is_range && !is_variadic_arg {
p.error('cannot range over type `$typ`')
}
if !is_variadic_arg {
if p.is_js {
p.genln('var $tmp = $expr;')
} else {
p.genln('$typ $tmp = $expr;')
}
}
// TODO var_type := if...
i := p.get_tmp()
if is_variadic_arg {
typ = typ[5..]
p.gen_for_varg_header(i, expr, typ, val)
}
else if is_range {
typ = 'int'
p.gen_for_range_header(i, range_end, tmp, typ, val)
}
else if is_arr {
typ = typ[6..]// all after `array_`
p.gen_for_header(i, tmp, typ, val)
}
else if is_str {
typ = 'byte'
p.gen_for_str_header(i, tmp, typ, val)
}
// println('for typ=$typ vartyp=$var_typ')
// Register temp var
if val != '_' {
p.register_var(Var {
name: val
typ: typ
ptr: typ.contains('*')
is_changed: true
is_mut: false
is_for_var: true
})
}
} else {
// `for a < b {`
p.gen('while (')
p.check_types(p.bool_expression(), 'bool')
p.genln(') {')
}
p.fspace()
p.check(.lcbr)
p.genln('')
p.statements()
p.close_scope()
p.for_expr_cnt--
p.returns = false // TODO handle loops that are guaranteed to return
}