languages/go
languages/go
1
0
Fork 0
mirror of https://github.com/golang/go synced 2024-09-04 23:44:16 +00:00
Code Issues Packages Projects Releases Wiki Activity

update type switch to match spec.

Browse source 
R=ken
OCL=34471
CL=34471
This commit is contained in:
Russ Cox 2009-09-09 00:18:16 -07:00
parent 5438be4541
commit 5d16d23362
8 changed files with 178 additions and 66 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
doc/go_spec.html
View file

@ -4367,7 +4367,6 @@ The following minimal alignment properties are guaranteed:
<h2 id="Implementation_differences"><font color=red>Implementation differences - TODO</font></h2>
<ul>
<li><font color=red>Implementation does not honor the restriction on goto statements and targets (no intervening declarations).</font></li>
<li><font color=red>A type switch must have an assignment in the guard expression and does not support multiple types per case.</font></li>
</ul>
</div>

5
src/cmd/gc/go.h
View file

@ -375,7 +375,7 @@ enum
OSELECT,
OSWITCH,
OTYPECASE,
OTYPESW,
OTYPESW, // l = r.(type)
// types
OTCHAN,
@ -676,7 +676,8 @@ EXTERN Node* curfn;
EXTERN int maxround;
EXTERN int widthptr;
EXTERN Node* typeswvar;
EXTERN Node* typesw;
EXTERN Node* nblank;
EXTERN char* structpkg;
extern int thechar;

63
src/cmd/gc/go.y
View file

@ -191,7 +191,7 @@ import_stmt:
my->lastlineno = $1;
import->block = 1; // at top level
}
import_stmt_list:
import_stmt
@ -230,10 +230,10 @@ import_package:
pkgimportname = $2;
if(strcmp($2->name, "main") == 0)
yyerror("cannot import package main");
// TODO(rsc): This is not quite precise enough a check
// (it excludes google/util/hash from importing hash)
// but it is enough to reduce confusion during the
// but it is enough to reduce confusion during the
// 2009/09/01 release when all the "import myself"
// statements have to go away in programs building
// against the release. Once the programs have converted
@ -424,7 +424,7 @@ simple_stmt:
yyerror("expr.(type) must be alone in list");
else if($1->next != nil)
yyerror("argument count mismatch: %d = %d", count($1), 1);
$$ = nod(OTYPESW, $1->n, $3->n->left);
$$ = nod(OTYPESW, $1->n, $3->n->right);
break;
}
$$ = colas($1, $3);
@ -443,30 +443,19 @@ simple_stmt:
case:
LCASE expr_or_type_list ':'
{
Node *n, *ntype;
Node *n;
// will be converted to OCASE
// right will point to next case
// done in casebody()
poptodcl();
$$ = nod(OXCASE, N, N);
if(typeswvar != N && typeswvar->right != N) {
// type switch
ntype = $2->n;
if($2->next != nil)
yyerror("type switch case cannot be list");
if(ntype->op == OLITERAL && ntype->val.ctype == CTNIL) {
// case nil
$$->list = list1(nod(OTYPECASE, N, N));
break;
}
n = newname(typeswvar->right->sym);
$$->list = $2;
if(typesw != N && typesw->right != N && (n=typesw->right->left) != N) {
// type switch - declare variable
n = newname(n->sym);
declare(n, dclcontext);
n->ntype = ntype;
$$->list = list1(nod(OTYPECASE, n, N));
} else {
// expr switch
$$->list = $2;
$$->nname = n;
}
break;
}
@ -490,8 +479,16 @@ case:
}
| LDEFAULT ':'
{
Node *n;
poptodcl();
$$ = nod(OXCASE, N, N);
if(typesw != N && typesw->right != N && (n=typesw->right->left) != N) {
// type switch - declare variable
n = newname(n->sym);
declare(n, dclcontext);
$$->nname = n;
}
}
compound_stmt:
@ -637,18 +634,16 @@ switch_stmt:
{
Node *n;
n = $3->ntest;
if(n != N && n->op == OTYPESW)
n = n->left;
else
if(n != N && n->op != OTYPESW)
n = N;
typeswvar = nod(OXXX, typeswvar, n);
typesw = nod(OXXX, typesw, n);
}
switch_body
{
$$ = $3;
$$->op = OSWITCH;
$$->list = $5;
typeswvar = typeswvar->left;
typesw = typesw->left;
popdcl();
}
@ -823,7 +818,7 @@ pexpr:
}
| pexpr '.' '(' LTYPE ')'
{
$$ = nod(OTYPESW, $1, N);
$$ = nod(OTYPESW, N, $1);
}
| pexpr '[' expr ']'
{
@ -1289,20 +1284,14 @@ arg_type:
name_or_type
| sym name_or_type
{
$$ = $1->def;
if($$ == N) {
$$ = nod(ONONAME, N, N);
$$->sym = $1;
}
$$ = nod(ONONAME, N, N);
$$->sym = $1;
$$ = nod(OKEY, $$, $2);
}
| sym dotdotdot
{
$$ = $1->def;
if($$ == N) {
$$ = nod(ONONAME, N, N);
$$->sym = $1;
}
$$ = nod(ONONAME, N, N);
$$->sym = $1;
$$ = nod(OKEY, $$, $2);
}
| dotdotdot

1
src/cmd/gc/lex.c
View file

@ -1359,6 +1359,7 @@ lexinit(void)
s->def->sym = s;
types[TBLANK] = typ(TBLANK);
s->def->type = types[TBLANK];
nblank = s->def;
}
struct

80
src/cmd/gc/swt.c
View file

@ -249,13 +249,13 @@ newlabel(void)
* deal with fallthrough, break, unreachable statements
*/
void
casebody(Node *sw)
casebody(Node *sw, Node *typeswvar)
{
Node *os, *oc, *n, *c, *last;
Node *def;
NodeList *cas, *stat, *l, *lc;
Node *go, *br;
int32 lno;
int32 lno, needvar;
lno = setlineno(sw);
if(sw->list == nil)
@ -274,6 +274,7 @@ casebody(Node *sw)
if(n->op != OXCASE)
fatal("casebody %O", n->op);
n->op = OCASE;
needvar = count(n->list) != 1 || n->list->n->op == OLITERAL;
go = nod(OGOTO, newlabel(), N);
if(n->list == nil) {
@ -300,6 +301,14 @@ casebody(Node *sw)
}
stat = list(stat, nod(OLABEL, go->left, N));
if(typeswvar && needvar && n->nname != N) {
NodeList *l;
l = list1(nod(ODCL, n->nname, N));
l = list(l, nod(OAS, n->nname, typeswvar));
typechecklist(l, Etop);
stat = concat(stat, l);
}
stat = concat(stat, n->nbody);
// botch - shouldnt fall thru declaration
@ -348,16 +357,16 @@ mkcaselist(Node *sw, int arg)
switch(arg) {
case Stype:
c->hash = 0;
if(n->left->left == N) {
if(n->left->op == OLITERAL) {
c->type = Ttypenil;
continue;
}
if(istype(n->left->left->type, TINTER)) {
if(istype(n->left->type, TINTER)) {
c->type = Ttypevar;
continue;
}
c->hash = typehash(n->left->left->type);
c->hash = typehash(n->left->type);
c->type = Ttypeconst;
continue;
@ -483,6 +492,7 @@ exprswitch(Node *sw)
Type *t;
int arg, ncase;
casebody(sw, N);
arg = Snorm;
if(isconst(sw->ntest, CTBOOL)) {
@ -564,13 +574,18 @@ typeone(Node *t)
NodeList *init;
Node *a, *b, *var;
var = t->left->left;
init = list1(nod(ODCL, var, N));
var = t->nname;
init = nil;
if(var == N) {
typecheck(&nblank, Erv | Easgn);
var = nblank;
} else
init = list1(nod(ODCL, var, N));
a = nod(OAS2, N, N);
a->list = list(list1(var), boolname); // var,bool =
b = nod(ODOTTYPE, facename, N);
b->type = t->left->left->type; // interface.(type)
b->type = t->left->type; // interface.(type)
a->rlist = list1(b);
typecheck(&a, Etop);
init = list(init, a);
@ -678,6 +693,8 @@ typeswitch(Node *sw)
typecheck(&a, Etop);
cas = list(cas, a);
casebody(sw, facename);
boolname = nod(OXXX, N, N);
tempname(boolname, types[TBOOL]);
typecheck(&boolname, Erv);
@ -758,10 +775,10 @@ walkswitch(Node *sw)
sw->ntest = nodbool(1);
typecheck(&sw->ntest, Erv);
}
casebody(sw);
if(sw->ntest->op == OTYPESW) {
typeswitch(sw);
//dump("sw", sw);
return;
}
exprswitch(sw);
@ -776,7 +793,7 @@ typecheckswitch(Node *n)
int top, lno;
Type *t;
NodeList *l, *ll;
Node *ncase;
Node *ncase, *nvar;
Node *def;
lno = lineno;
@ -784,11 +801,11 @@ typecheckswitch(Node *n)
if(n->ntest != N && n->ntest->op == OTYPESW) {
// type switch
typecheck(&n->ntest, Etop);
top = Etype;
t = n->ntest->type;
typecheck(&n->ntest->right, Erv);
t = n->ntest->right->type;
if(t != T && t->etype != TINTER)
yyerror("cannot type switch on non-interface value %+N", n->ntest);
yyerror("cannot type switch on non-interface value %+N", n->ntest->right);
} else {
// value switch
top = Erv;
@ -814,12 +831,37 @@ typecheckswitch(Node *n)
} else {
for(ll=ncase->list; ll; ll=ll->next) {
setlineno(ll->n);
typecheck(&ll->n, Erv); // TODO(rsc): top
if(ll->n->type == T || t == T || top != Erv)
typecheck(&ll->n, Erv | Etype);
if(ll->n->type == T || t == T)
continue;
defaultlit(&ll->n, t);
if(ll->n->type != T && !eqtype(ll->n->type, t))
yyerror("case %+N in switch of %+N %#O", ll->n, n->ntest, ll->n->op);
switch(top) {
case Erv: // expression switch
defaultlit(&ll->n, t);
if(ll->n->op == OTYPE)
yyerror("type %T is not an expression", ll->n->type);
else if(ll->n->type != T && !eqtype(ll->n->type, t))
yyerror("case %+N in switch of %+N %#O", ll->n, n->ntest, ll->n->op);
break;
case Etype: // type switch
if(ll->n->op == OLITERAL && istype(ll->n->type, TNIL))
;
else if(ll->n->op != OTYPE && ll->n->type != T)
yyerror("%#N is not a type", ll->n);
break;
}
}
}
if(top == Etype && n->type != T) {
ll = ncase->list;
nvar = ncase->nname;
if(nvar != N) {
if(ll && ll->next == nil && ll->n->type != T && !istype(ll->n->type, TNIL)) {
// single entry type switch
nvar->ntype = typenod(ll->n->type);
} else {
// multiple entry type switch or default
nvar->ntype = typenod(n->type);
}
}
}
typechecklist(ncase->nbody, Etop);

2
src/pkg/datafmt/datafmt.go
View file

@ -415,7 +415,7 @@ func (s *State) error(msg string) {
//
func typename(typ reflect.Type) string {
switch t := typ.(type) {
switch typ.(type) {
case *reflect.ArrayType:
return "array";
case *reflect.SliceType:

8
src/pkg/json/struct.go
View file

@ -19,12 +19,8 @@ type _StructBuilder struct {
var nobuilder *_StructBuilder
func isfloat(v reflect.Value) bool {
switch v := v.(type) {
case *reflect.FloatValue:
return true;
case *reflect.Float32Value:
return true;
case *reflect.Float64Value:
switch v.(type) {
case *reflect.FloatValue, *reflect.Float32Value, *reflect.Float64Value:
return true;
}
return false;

84
test/typeswitch1.go Normal file
View file

@ -0,0 +1,84 @@
// $G $D/$F.go && $L $F.$A && ./$A.out
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import "fmt"
const (
a = iota;
b;
c;
d;
e;
)
var x = []int{1,2,3}
func f(x int, len *byte) {
*len = byte(x);
}
func whatis(x interface{}) string {
switch xx := x.(type) {
default:
return fmt.Sprint("default ", xx);
case int, int8, int16, int32:
return fmt.Sprint("signed ", xx);
case int64:
return fmt.Sprint("signed64 ", int64(xx));
case uint, uint8, uint16, uint32:
return fmt.Sprint("unsigned ", xx);
case uint64:
return fmt.Sprint("unsigned64 ", uint64(xx));
case nil:
return fmt.Sprint("nil ", xx);
}
panic("not reached");
}
func whatis1(x interface{}) string {
xx := x;
switch xx.(type) {
default:
return fmt.Sprint("default ", xx);
case int, int8, int16, int32:
return fmt.Sprint("signed ", xx);
case int64:
return fmt.Sprint("signed64 ", xx.(int64));
case uint, uint8, uint16, uint32:
return fmt.Sprint("unsigned ", xx);
case uint64:
return fmt.Sprint("unsigned64 ", xx.(uint64));
case nil:
return fmt.Sprint("nil ", xx);
}
panic("not reached");
}
func check(x interface{}, s string) {
w := whatis(x);
if w != s {
fmt.Println("whatis", x, "=>", w, "!=", s);
panic();
}
w = whatis1(x);
if w != s {
fmt.Println("whatis1", x, "=>", w, "!=", s);
panic();
}
}
func main() {
check(1, "signed 1");
check(uint(1), "unsigned 1");
check(int64(1), "signed64 1");
check(uint64(1), "unsigned64 1");
check(1.5, "default 1.5");
check(nil, "nil <nil>");
}