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parser: match expression + match fixes

pull/1755/head
Danil-Lapirow 2019-08-27 00:39:11 +03:00 committed by Alexander Medvednikov
parent b6336f730b
commit 7edcbeca1a
2 changed files with 276 additions and 12 deletions
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190
compiler/parser.v
View File

@ -64,6 +64,7 @@ mut:
builtin_mod bool
vh_lines []string
inside_if_expr bool
inside_unwrapping_match_statement bool
is_struct_init bool
if_expr_cnt int
for_expr_cnt int // to detect whether `continue` can be used
@ -1019,6 +1020,7 @@ fn (p mut Parser) statements() string {
fn (p mut Parser) statements_no_rcbr() string {
p.cur_fn.open_scope()
if !p.inside_if_expr {
p.genln('')
}
@ -1049,6 +1051,7 @@ fn (p mut Parser) statements_no_rcbr() string {
}
//p.fmt_dec()
// println('close scope line=$p.scanner.line_nr')
p.close_scope()
return last_st_typ
}
@ -1152,8 +1155,10 @@ fn (p mut Parser) statement(add_semi bool) string {
p.if_st(false, 0)
case Token.key_for:
p.for_st()
case Token.key_switch, Token.key_match:
case Token.key_switch:
p.switch_statement()
case Token.key_match:
p.match_statement(false)
case Token.key_mut, Token.key_static:
p.var_decl()
case Token.key_return:
@ -2409,6 +2414,9 @@ fn (p mut Parser) factor() string {
case Token.key_if:
typ = p.if_st(true, 0)
return typ
case Token.key_match:
typ = p.match_statement(true)
return typ
default:
if p.pref.is_verbose || p.pref.is_debug {
next := p.peek()
@ -3350,6 +3358,186 @@ fn (p mut Parser) switch_statement() {
p.returns = false // only get here when no default, so return is not guaranteed
}
// Returns typ if used as expession
fn (p mut Parser) match_statement(is_expr bool) string {
p.check(.key_match)
p.cgen.start_tmp()
typ := p.bool_expression()
expr := p.cgen.end_tmp()
// is it safe to use p.cgen.insert_before ???
tmp_var := p.get_tmp()
p.cgen.insert_before('$typ $tmp_var = $expr;')
p.check(.lcbr)
mut i := 0
mut all_cases_return := true
// stores typ of resulting variable
mut res_typ := ''
defer {
p.check(.rcbr)
}
for p.tok != .rcbr {
if p.tok == .key_else {
p.check(.key_else)
p.check(.arrow)
// unwrap match if there is only else
if i == 0 {
if is_expr {
// statements are dissallowed (if match is expression) so user cant declare variables there and so on
// allow braces is else
got_brace := p.tok == .lcbr
if got_brace {
p.check(.lcbr)
}
p.gen('( ')
res_typ = p.bool_expression()
p.gen(' )')
// allow braces in else
if got_brace {
p.check(.rcbr)
}
return res_typ
} else {
p.match_parse_statement_branch()
p.returns = all_cases_return && p.returns
return ''
}
}
if is_expr {
// statements are dissallowed (if match is expression) so user cant declare variables there and so on
p.gen(':(')
// allow braces is else
got_brace := p.tok == .lcbr
if got_brace {
p.check(.lcbr)
}
p.check_types(p.bool_expression(), res_typ)
// allow braces in else
if got_brace {
p.check(.rcbr)
}
p.gen(strings.repeat(`)`, i+1))
return res_typ
} else {
p.genln('else // default:')
p.match_parse_statement_branch()
p.returns = all_cases_return && p.returns
return ''
}
}
if i > 0 {
if is_expr {
p.gen(': (')
} else {
p.gen('else ')
}
} else if is_expr {
p.gen('(')
}
if is_expr {
p.gen('(')
} else {
p.gen('if (')
}
// Multiple checks separated by comma
mut got_comma := false
for {
if got_comma {
p.gen(') || (')
}
if typ == 'string' {
// TODO: use tmp variable
// p.gen('string_eq($tmp_var, ')
p.gen('string_eq($tmp_var, ')
}
else {
// TODO: use tmp variable
// p.gen('($tmp_var == ')
p.gen('($tmp_var == ')
}
p.expected_type = typ
p.check_types(p.bool_expression(), typ)
p.expected_type = ''
if p.tok != .comma {
break
}
p.check(.comma)
got_comma = true
}
p.gen(') )')
p.check(.arrow)
// statements are dissallowed (if match is expression) so user cant declare variables there and so on
if is_expr {
p.gen('? (')
// braces are required for now
p.check(.lcbr)
if i == 0 {
// on the first iteration we set value of res_typ
res_typ = p.bool_expression()
} else {
// later on we check that the value is of res_typ type
p.check_types(p.bool_expression(), res_typ)
}
// braces are required for now
p.check(.rcbr)
p.gen(')')
}
else {
p.match_parse_statement_branch()
// p.gen(')')
}
all_cases_return = all_cases_return && p.returns
i++
}
if is_expr {
// we get here if no else found, ternary requires "else" branch
p.error('Match expession requires "else"')
}
p.returns = false // only get here when no default, so return is not guaranteed
return ''
}
fn (p mut Parser) match_parse_statement_branch(){
p.check(.lcbr)
p.genln('{ ')
p.statements()
}
fn (p mut Parser) assert_statement() {
if p.first_pass() {
return

96
compiler/tests/match_test.v
View File

@ -1,12 +1,88 @@
fn test_match() {
a := 3
mut b := 0
match a {
2 => println('two')
3 => println('three')
b = 3
4 => println('four')
else => println('???')
enum Color{
red, green, blue
}
assert b == 3
fn test_match_integers() {
// a := 3
// mut b := 0
// match a {
// 2 => println('two')
// 3 => println('three')
// b = 3
// 4 => println('four')
// else => println('???')
// }
// assert b == 3
assert match 2 {
1 => {2}
2 => {3}
else => {5}
} == 3
assert match 0 {
1 => {2}
2 => {3}
else => 5
} == 5
assert match 1 {
else => {5}
} == 5
mut a := 0
match 2 {
0 => {a = 1}
1 => {a = 2}
else => {
a = 3
println('a is $a')
}
}
assert a == 3
a = 0
match 1 {
0 => {a = 1}
1 => {
a = 2
a = a + 2
a = a + 2
}
}
assert a == 6
a = 0
match 1 {
else => {
a = -2
}
}
assert a == -2
}
fn test_match_enums(){
mut b := Color.red
match b{
.red => {
b = .green
}
.green => {b = .blue}
else => {
println('b is ${b.str()}')
b = .red
}
}
assert b == .green
match b{
.red => {
b = .green
}
else => {
println('b is ${b.str()}')
b = .blue
}
}
assert b == .blue
}