qbit/go
1
0
Fork 0
mirror of https://github.com/golang/go synced 2024-11-21 22:44:40 -07:00
Code Releases Activity

remove assignment cases from switch

Browse Source 
R=r
OCL=26480
CL=26480
This commit is contained in:
Ken Thompson 2009-03-18 12:13:42 -07:00
parent bd3c478f93
commit 1cdcfda140
2 changed files with 51 additions and 105 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
src/cmd/gc/swt.c
View File

@ -44,49 +44,15 @@ sw0(Node *c, Type *place, int arg)
return T;
}
walktype(c, Erv);
return T;
break;
case OTYPESW:
if(arg != Stype)
yyerror("inappropriate type case");
return T;
break;
case OAS:
yyerror("inappropriate assignment in a case statement");
break;
}
walktype(c->left, Elv);
r = c->right;
if(c == N)
return T;
switch(r->op) {
default:
goto bad;
case ORECV:
// <-chan
walktype(r->left, Erv);
if(!istype(r->left->type, TCHAN))
goto bad;
break;
case OINDEX:
// map[e]
walktype(r->left, Erv);
if(!istype(r->left->type, TMAP))
goto bad;
break;
case ODOTTYPE:
// interface.(type)
walktype(r->left, Erv);
if(!istype(r->left->type, TINTER))
goto bad;
break;
}
c->type = types[TBOOL];
if(arg != Strue)
goto bad;
return T;
bad:
yyerror("inappropriate assignment in a case statement");
return T;
}
@ -311,26 +277,6 @@ loop:
t->ninit = N;
}
if(t->left->op == OAS) {
if(bool == N) {
bool = nod(OXXX, N, N);
tempname(bool, types[TBOOL]);
}
t->left->left = nod(OLIST, t->left->left, bool);
cas = list(cas, t->left); // v,bool = rhs
a = nod(OIF, N, N);
a->nbody = t->right; // then goto l
a->ntest = bool;
if(arg != Strue)
a->ntest = nod(ONOT, bool, N);
cas = list(cas, a); // if bool goto l
t = listnext(&save);
goto loop;
}
switch(arg) {
default:
// not bool const

96
test/typeswitch.go
View File

@ -62,30 +62,30 @@ func f(i int) interface{} {
func main() {
// type guard style
for i := Bool; i < Last; i++ {
switch v := f(i); true {
case x := v.(bool):
assert(x == true && i == Bool, "switch 1 bool");
case x := v.(int):
assert(x == 7 && i == Int, "switch 1 int");
case x := v.(float):
assert(x == 7.4 && i == Float, "switch 1 float");
case x := v.(string):
assert(x == "hello" && i == String, "switch 1 string");
case x := v.(S):
assert(x.a == 1234 && i == Struct, "switch 1 struct");
case x := v.(chan int):
assert(x == c && i == Chan, "switch 1 chan");
case x := v.([]int):
assert(x[3] == 3 && i == Array, "switch 1 array");
case x := v.(map[string]int):
assert(x == m && i == Map, "switch 1 map");
case x := v.(func(i int) interface{}):
assert(x == f && i == Func, "switch 1 fun");
default:
assert(false, "switch 1 unknown");
}
}
// for i := Bool; i < Last; i++ {
// switch v := f(i); true {
// case x := v.(bool):
// assert(x == true && i == Bool, "switch 1 bool");
// case x := v.(int):
// assert(x == 7 && i == Int, "switch 1 int");
// case x := v.(float):
// assert(x == 7.4 && i == Float, "switch 1 float");
// case x := v.(string):
// assert(x == "hello" && i == String, "switch 1 string");
// case x := v.(S):
// assert(x.a == 1234 && i == Struct, "switch 1 struct");
// case x := v.(chan int):
// assert(x == c && i == Chan, "switch 1 chan");
// case x := v.([]int):
// assert(x[3] == 3 && i == Array, "switch 1 array");
// case x := v.(map[string]int):
// assert(x == m && i == Map, "switch 1 map");
// case x := v.(func(i int) interface{}):
// assert(x == f && i == Func, "switch 1 fun");
// default:
// assert(false, "switch 1 unknown");
// }
// }
// type switch style
for i := Bool; i < Last; i++ {
@ -135,24 +135,24 @@ func main() {
assert(false, "switch 4 unknown");
}
switch true {
case x := f(Int).(float):
assert(false, "switch 5 type guard wrong type");
case x := f(Int).(int):
assert(x == 7, "switch 5 type guard");
default:
assert(false, "switch 5 unknown");
}
// switch true {
// case x := f(Int).(float):
// assert(false, "switch 5 type guard wrong type");
// case x := f(Int).(int):
// assert(x == 7, "switch 5 type guard");
// default:
// assert(false, "switch 5 unknown");
// }
m["7"] = 7;
switch true {
case x := m["6"]:
assert(false, "switch 6 map reference wrong");
case x := m["7"]:
assert(x == 7, "switch 6 map reference");
default:
assert(false, "switch 6 unknown");
}
// switch true {
// case x := m["6"]:
// assert(false, "switch 6 map reference wrong");
// case x := m["7"]:
// assert(x == 7, "switch 6 map reference");
// default:
// assert(false, "switch 6 unknown");
// }
go func() { <-c; c <- 77; } ();
// guarantee the channel is ready
@ -161,13 +161,13 @@ func main() {
sys.Gosched();
}
dummyc := make(chan int);
switch true {
case x := <-dummyc:
assert(false, "switch 7 chan wrong");
case x := <-c:
assert(x == 77, "switch 7 chan");
default:
assert(false, "switch 7 unknown");
}
// switch true {
// case x := <-dummyc:
// assert(false, "switch 7 chan wrong");
// case x := <-c:
// assert(x == 77, "switch 7 chan");
// default:
// assert(false, "switch 7 unknown");
// }
}