reflect: implement method values
Fixes #1517.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/7906043
diff --git a/src/pkg/reflect/all_test.go b/src/pkg/reflect/all_test.go
index 97b3a9f..9a4dd6c 100644
--- a/src/pkg/reflect/all_test.go
+++ b/src/pkg/reflect/all_test.go
@@ -1458,7 +1458,7 @@
// This will be index 1.
func (p Point) Dist(scale int) int {
- // println("Point.Dist", p.x, p.y, scale)
+ //println("Point.Dist", p.x, p.y, scale)
return p.x*p.x*scale + p.y*p.y*scale
}
@@ -1474,23 +1474,23 @@
if !ok {
t.Fatalf("method by name failed")
}
- m.Func.Call([]Value{ValueOf(p), ValueOf(10)})[0].Int()
- if i != 250 {
- t.Errorf("Type MethodByName returned %d; want 250", i)
+ i = m.Func.Call([]Value{ValueOf(p), ValueOf(11)})[0].Int()
+ if i != 275 {
+ t.Errorf("Type MethodByName returned %d; want 275", i)
}
- i = TypeOf(&p).Method(1).Func.Call([]Value{ValueOf(&p), ValueOf(10)})[0].Int()
- if i != 250 {
- t.Errorf("Pointer Type Method returned %d; want 250", i)
+ i = TypeOf(&p).Method(1).Func.Call([]Value{ValueOf(&p), ValueOf(12)})[0].Int()
+ if i != 300 {
+ t.Errorf("Pointer Type Method returned %d; want 300", i)
}
m, ok = TypeOf(&p).MethodByName("Dist")
if !ok {
t.Fatalf("ptr method by name failed")
}
- i = m.Func.Call([]Value{ValueOf(&p), ValueOf(10)})[0].Int()
- if i != 250 {
- t.Errorf("Pointer Type MethodByName returned %d; want 250", i)
+ i = m.Func.Call([]Value{ValueOf(&p), ValueOf(13)})[0].Int()
+ if i != 325 {
+ t.Errorf("Pointer Type MethodByName returned %d; want 325", i)
}
// Curried method of value.
@@ -1499,17 +1499,17 @@
if tt := v.Type(); tt != tfunc {
t.Errorf("Value Method Type is %s; want %s", tt, tfunc)
}
- i = v.Call([]Value{ValueOf(10)})[0].Int()
- if i != 250 {
- t.Errorf("Value Method returned %d; want 250", i)
+ i = v.Call([]Value{ValueOf(14)})[0].Int()
+ if i != 350 {
+ t.Errorf("Value Method returned %d; want 350", i)
}
v = ValueOf(p).MethodByName("Dist")
if tt := v.Type(); tt != tfunc {
t.Errorf("Value MethodByName Type is %s; want %s", tt, tfunc)
}
- i = v.Call([]Value{ValueOf(10)})[0].Int()
- if i != 250 {
- t.Errorf("Value MethodByName returned %d; want 250", i)
+ i = v.Call([]Value{ValueOf(15)})[0].Int()
+ if i != 375 {
+ t.Errorf("Value MethodByName returned %d; want 375", i)
}
// Curried method of pointer.
@@ -1517,17 +1517,84 @@
if tt := v.Type(); tt != tfunc {
t.Errorf("Pointer Value Method Type is %s; want %s", tt, tfunc)
}
- i = v.Call([]Value{ValueOf(10)})[0].Int()
- if i != 250 {
- t.Errorf("Pointer Value Method returned %d; want 250", i)
+ i = v.Call([]Value{ValueOf(16)})[0].Int()
+ if i != 400 {
+ t.Errorf("Pointer Value Method returned %d; want 400", i)
}
v = ValueOf(&p).MethodByName("Dist")
if tt := v.Type(); tt != tfunc {
t.Errorf("Pointer Value MethodByName Type is %s; want %s", tt, tfunc)
}
- i = v.Call([]Value{ValueOf(10)})[0].Int()
+ i = v.Call([]Value{ValueOf(17)})[0].Int()
+ if i != 425 {
+ t.Errorf("Pointer Value MethodByName returned %d; want 425", i)
+ }
+
+ // Curried method of interface value.
+ // Have to wrap interface value in a struct to get at it.
+ // Passing it to ValueOf directly would
+ // access the underlying Point, not the interface.
+ var x interface {
+ Dist(int) int
+ } = p
+ pv := ValueOf(&x).Elem()
+ v = pv.Method(0)
+ if tt := v.Type(); tt != tfunc {
+ t.Errorf("Interface Method Type is %s; want %s", tt, tfunc)
+ }
+ i = v.Call([]Value{ValueOf(18)})[0].Int()
+ if i != 450 {
+ t.Errorf("Interface Method returned %d; want 450", i)
+ }
+ v = pv.MethodByName("Dist")
+ if tt := v.Type(); tt != tfunc {
+ t.Errorf("Interface MethodByName Type is %s; want %s", tt, tfunc)
+ }
+ i = v.Call([]Value{ValueOf(19)})[0].Int()
+ if i != 475 {
+ t.Errorf("Interface MethodByName returned %d; want 475", i)
+ }
+}
+
+func TestMethodValue(t *testing.T) {
+ p := Point{3, 4}
+ var i int64
+
+ // Curried method of value.
+ tfunc := TypeOf((func(int) int)(nil))
+ v := ValueOf(p).Method(1)
+ if tt := v.Type(); tt != tfunc {
+ t.Errorf("Value Method Type is %s; want %s", tt, tfunc)
+ }
+ i = ValueOf(v.Interface()).Call([]Value{ValueOf(10)})[0].Int()
if i != 250 {
- t.Errorf("Pointer Value MethodByName returned %d; want 250", i)
+ t.Errorf("Value Method returned %d; want 250", i)
+ }
+ v = ValueOf(p).MethodByName("Dist")
+ if tt := v.Type(); tt != tfunc {
+ t.Errorf("Value MethodByName Type is %s; want %s", tt, tfunc)
+ }
+ i = ValueOf(v.Interface()).Call([]Value{ValueOf(11)})[0].Int()
+ if i != 275 {
+ t.Errorf("Value MethodByName returned %d; want 275", i)
+ }
+
+ // Curried method of pointer.
+ v = ValueOf(&p).Method(1)
+ if tt := v.Type(); tt != tfunc {
+ t.Errorf("Pointer Value Method Type is %s; want %s", tt, tfunc)
+ }
+ i = ValueOf(v.Interface()).Call([]Value{ValueOf(12)})[0].Int()
+ if i != 300 {
+ t.Errorf("Pointer Value Method returned %d; want 300", i)
+ }
+ v = ValueOf(&p).MethodByName("Dist")
+ if tt := v.Type(); tt != tfunc {
+ t.Errorf("Pointer Value MethodByName Type is %s; want %s", tt, tfunc)
+ }
+ i = ValueOf(v.Interface()).Call([]Value{ValueOf(13)})[0].Int()
+ if i != 325 {
+ t.Errorf("Pointer Value MethodByName returned %d; want 325", i)
}
// Curried method of interface value.
@@ -1544,20 +1611,203 @@
if tt := v.Type(); tt != tfunc {
t.Errorf("Interface Method Type is %s; want %s", tt, tfunc)
}
- i = v.Call([]Value{ValueOf(10)})[0].Int()
- if i != 250 {
- t.Errorf("Interface Method returned %d; want 250", i)
+ i = ValueOf(v.Interface()).Call([]Value{ValueOf(14)})[0].Int()
+ if i != 350 {
+ t.Errorf("Interface Method returned %d; want 350", i)
}
v = pv.MethodByName("Dist")
if tt := v.Type(); tt != tfunc {
t.Errorf("Interface MethodByName Type is %s; want %s", tt, tfunc)
}
- i = v.Call([]Value{ValueOf(10)})[0].Int()
- if i != 250 {
- t.Errorf("Interface MethodByName returned %d; want 250", i)
+ i = ValueOf(v.Interface()).Call([]Value{ValueOf(15)})[0].Int()
+ if i != 375 {
+ t.Errorf("Interface MethodByName returned %d; want 375", i)
}
}
+// Reflect version of $GOROOT/test/method5.go
+
+// Concrete types implementing M method.
+// Smaller than a word, word-sized, larger than a word.
+// Value and pointer receivers.
+
+type Tinter interface {
+ M(int, byte) (byte, int)
+}
+
+type Tsmallv byte
+
+func (v Tsmallv) M(x int, b byte) (byte, int) { return b, x + int(v) }
+
+type Tsmallp byte
+
+func (p *Tsmallp) M(x int, b byte) (byte, int) { return b, x + int(*p) }
+
+type Twordv uintptr
+
+func (v Twordv) M(x int, b byte) (byte, int) { return b, x + int(v) }
+
+type Twordp uintptr
+
+func (p *Twordp) M(x int, b byte) (byte, int) { return b, x + int(*p) }
+
+type Tbigv [2]uintptr
+
+func (v Tbigv) M(x int, b byte) (byte, int) { return b, x + int(v[0]) + int(v[1]) }
+
+type Tbigp [2]uintptr
+
+func (p *Tbigp) M(x int, b byte) (byte, int) { return b, x + int(p[0]) + int(p[1]) }
+
+// Again, with an unexported method.
+
+type tsmallv byte
+
+func (v tsmallv) m(x int, b byte) (byte, int) { return b, x + int(v) }
+
+type tsmallp byte
+
+func (p *tsmallp) m(x int, b byte) (byte, int) { return b, x + int(*p) }
+
+type twordv uintptr
+
+func (v twordv) m(x int, b byte) (byte, int) { return b, x + int(v) }
+
+type twordp uintptr
+
+func (p *twordp) m(x int, b byte) (byte, int) { return b, x + int(*p) }
+
+type tbigv [2]uintptr
+
+func (v tbigv) m(x int, b byte) (byte, int) { return b, x + int(v[0]) + int(v[1]) }
+
+type tbigp [2]uintptr
+
+func (p *tbigp) m(x int, b byte) (byte, int) { return b, x + int(p[0]) + int(p[1]) }
+
+type tinter interface {
+ m(int, byte) (byte, int)
+}
+
+// Embedding via pointer.
+
+type Tm1 struct {
+ Tm2
+}
+
+type Tm2 struct {
+ *Tm3
+}
+
+type Tm3 struct {
+ *Tm4
+}
+
+type Tm4 struct {
+}
+
+func (t4 Tm4) M(x int, b byte) (byte, int) { return b, x + 40 }
+
+func TestMethod5(t *testing.T) {
+ CheckF := func(name string, f func(int, byte) (byte, int), inc int) {
+ b, x := f(1000, 99)
+ if b != 99 || x != 1000+inc {
+ t.Errorf("%s(1000, 99) = %v, %v, want 99, %v", name, b, x, 1000+inc)
+ }
+ }
+
+ CheckV := func(name string, i Value, inc int) {
+ bx := i.Method(0).Call([]Value{ValueOf(1000), ValueOf(byte(99))})
+ b := bx[0].Interface()
+ x := bx[1].Interface()
+ if b != byte(99) || x != 1000+inc {
+ t.Errorf("direct %s.M(1000, 99) = %v, %v, want 99, %v", name, b, x, 1000+inc)
+ }
+
+ CheckF(name+".M", i.Method(0).Interface().(func(int, byte) (byte, int)), inc)
+ }
+
+ var TinterType = TypeOf(new(Tinter)).Elem()
+ var tinterType = TypeOf(new(tinter)).Elem()
+
+ CheckI := func(name string, i interface{}, inc int) {
+ v := ValueOf(i)
+ CheckV(name, v, inc)
+ CheckV("(i="+name+")", v.Convert(TinterType), inc)
+ }
+
+ sv := Tsmallv(1)
+ CheckI("sv", sv, 1)
+ CheckI("&sv", &sv, 1)
+
+ sp := Tsmallp(2)
+ CheckI("&sp", &sp, 2)
+
+ wv := Twordv(3)
+ CheckI("wv", wv, 3)
+ CheckI("&wv", &wv, 3)
+
+ wp := Twordp(4)
+ CheckI("&wp", &wp, 4)
+
+ bv := Tbigv([2]uintptr{5, 6})
+ CheckI("bv", bv, 11)
+ CheckI("&bv", &bv, 11)
+
+ bp := Tbigp([2]uintptr{7, 8})
+ CheckI("&bp", &bp, 15)
+
+ t4 := Tm4{}
+ t3 := Tm3{&t4}
+ t2 := Tm2{&t3}
+ t1 := Tm1{t2}
+ CheckI("t4", t4, 40)
+ CheckI("&t4", &t4, 40)
+ CheckI("t3", t3, 40)
+ CheckI("&t3", &t3, 40)
+ CheckI("t2", t2, 40)
+ CheckI("&t2", &t2, 40)
+ CheckI("t1", t1, 40)
+ CheckI("&t1", &t1, 40)
+
+ methodShouldPanic := func(name string, i interface{}) {
+ v := ValueOf(i)
+ m := v.Method(0)
+ shouldPanic(func() { m.Call([]Value{ValueOf(1000), ValueOf(byte(99))}) })
+ shouldPanic(func() { m.Interface() })
+
+ v = v.Convert(tinterType)
+ m = v.Method(0)
+ shouldPanic(func() { m.Call([]Value{ValueOf(1000), ValueOf(byte(99))}) })
+ shouldPanic(func() { m.Interface() })
+ }
+
+ _sv := tsmallv(1)
+ methodShouldPanic("_sv", _sv)
+ methodShouldPanic("&_sv", &_sv)
+
+ _sp := tsmallp(2)
+ methodShouldPanic("&_sp", &_sp)
+
+ _wv := twordv(3)
+ methodShouldPanic("_wv", _wv)
+ methodShouldPanic("&_wv", &_wv)
+
+ _wp := twordp(4)
+ methodShouldPanic("&_wp", &_wp)
+
+ _bv := tbigv([2]uintptr{5, 6})
+ methodShouldPanic("_bv", _bv)
+ methodShouldPanic("&_bv", &_bv)
+
+ _bp := tbigp([2]uintptr{7, 8})
+ methodShouldPanic("&_bp", &_bp)
+
+ var tnil Tinter
+ vnil := ValueOf(&tnil).Elem()
+ shouldPanic(func() { vnil.Method(0) })
+}
+
func TestInterfaceSet(t *testing.T) {
p := &Point{3, 4}
diff --git a/src/pkg/reflect/asm_386.s b/src/pkg/reflect/asm_386.s
index 27d3fa21..068ab64 100644
--- a/src/pkg/reflect/asm_386.s
+++ b/src/pkg/reflect/asm_386.s
@@ -3,7 +3,7 @@
// license that can be found in the LICENSE file.
// makeFuncStub is the code half of the function returned by MakeFunc.
-// See the comment on the declaration of makeFuncStub in value.go
+// See the comment on the declaration of makeFuncStub in makefunc.go
// for more details.
TEXT ·makeFuncStub(SB),7,$8
MOVL DX, 0(SP)
@@ -11,3 +11,13 @@
MOVL CX, 4(SP)
CALL ·callReflect(SB)
RET
+
+// methodValueCall is the code half of the function returned by makeMethodValue.
+// See the comment on the declaration of methodValueCall in makefunc.go
+// for more details.
+TEXT ·methodValueCall(SB),7,$8
+ MOVL DX, 0(SP)
+ LEAL arg+0(FP), CX
+ MOVL CX, 4(SP)
+ CALL ·callMethod(SB)
+ RET
diff --git a/src/pkg/reflect/asm_amd64.s b/src/pkg/reflect/asm_amd64.s
index d51d982..06a593a 100644
--- a/src/pkg/reflect/asm_amd64.s
+++ b/src/pkg/reflect/asm_amd64.s
@@ -3,7 +3,7 @@
// license that can be found in the LICENSE file.
// makeFuncStub is the code half of the function returned by MakeFunc.
-// See the comment on the declaration of makeFuncStub in value.go
+// See the comment on the declaration of makeFuncStub in makefunc.go
// for more details.
TEXT ·makeFuncStub(SB),7,$16
MOVQ DX, 0(SP)
@@ -11,3 +11,13 @@
MOVQ CX, 8(SP)
CALL ·callReflect(SB)
RET
+
+// methodValueCall is the code half of the function returned by makeMethodValue.
+// See the comment on the declaration of methodValueCall in makefunc.go
+// for more details.
+TEXT ·methodValueCall(SB),7,$16
+ MOVQ DX, 0(SP)
+ LEAQ arg+0(FP), CX
+ MOVQ CX, 8(SP)
+ CALL ·callMethod(SB)
+ RET
diff --git a/src/pkg/reflect/asm_arm.s b/src/pkg/reflect/asm_arm.s
index db487f8..4add1e3 100644
--- a/src/pkg/reflect/asm_arm.s
+++ b/src/pkg/reflect/asm_arm.s
@@ -3,7 +3,7 @@
// license that can be found in the LICENSE file.
// makeFuncStub is jumped to by the code generated by MakeFunc.
-// See the comment on the declaration of makeFuncStub in value.go
+// See the comment on the declaration of makeFuncStub in makefunc.go
// for more details.
TEXT ·makeFuncStub(SB),7,$8
MOVW R7, 4(R13)
@@ -11,3 +11,13 @@
MOVW R1, 8(R13)
BL ·callReflect(SB)
RET
+
+// methodValueCall is the code half of the function returned by makeMethodValue.
+// See the comment on the declaration of methodValueCall in makefunc.go
+// for more details.
+TEXT ·methodValueCall(SB),7,$8
+ MOVW R7, 4(R13)
+ MOVW $arg+0(FP), R1
+ MOVW R1, 8(R13)
+ BL ·callMethod(SB)
+ RET
diff --git a/src/pkg/reflect/deepequal.go b/src/pkg/reflect/deepequal.go
index db04796..915afed 100644
--- a/src/pkg/reflect/deepequal.go
+++ b/src/pkg/reflect/deepequal.go
@@ -118,8 +118,6 @@
// Normal equality suffices
return valueInterface(v1, false) == valueInterface(v2, false)
}
-
- panic("Not reached")
}
// DeepEqual tests for deep equality. It uses normal == equality where
diff --git a/src/pkg/reflect/makefunc.go b/src/pkg/reflect/makefunc.go
index 024f938..ccdd683 100644
--- a/src/pkg/reflect/makefunc.go
+++ b/src/pkg/reflect/makefunc.go
@@ -48,8 +48,8 @@
t := typ.common()
ftyp := (*funcType)(unsafe.Pointer(t))
- // indirect Go func value (dummy) to obtain
- // actual code address. (A Go func is a pointer
+ // Indirect Go func value (dummy) to obtain
+ // actual code address. (A Go func value is a pointer
// to a C function pointer. http://golang.org/s/go11func.)
dummy := makeFuncStub
code := **(**uintptr)(unsafe.Pointer(&dummy))
@@ -65,3 +65,56 @@
// where ctxt is the context register and frame is a pointer to the first
// word in the passed-in argument frame.
func makeFuncStub()
+
+type methodValue struct {
+ fn uintptr
+ method int
+ rcvr Value
+}
+
+// makeMethodValue converts v from the rcvr+method index representation
+// of a method value to an actual method func value, which is
+// basically the receiver value with a special bit set, into a true
+// func value - a value holding an actual func. The output is
+// semantically equivalent to the input as far as the user of package
+// reflect can tell, but the true func representation can be handled
+// by code like Convert and Interface and Assign.
+func makeMethodValue(op string, v Value) Value {
+ if v.flag&flagMethod == 0 {
+ panic("reflect: internal error: invalid use of makePartialFunc")
+ }
+
+ // Ignoring the flagMethod bit, v describes the receiver, not the method type.
+ fl := v.flag & (flagRO | flagAddr | flagIndir)
+ fl |= flag(v.typ.Kind()) << flagKindShift
+ rcvr := Value{v.typ, v.val, fl}
+
+ // v.Type returns the actual type of the method value.
+ funcType := v.Type().(*rtype)
+
+ // Indirect Go func value (dummy) to obtain
+ // actual code address. (A Go func value is a pointer
+ // to a C function pointer. http://golang.org/s/go11func.)
+ dummy := methodValueCall
+ code := **(**uintptr)(unsafe.Pointer(&dummy))
+
+ fv := &methodValue{
+ fn: code,
+ method: int(v.flag) >> flagMethodShift,
+ rcvr: rcvr,
+ }
+
+ // Cause panic if method is not appropriate.
+ // The panic would still happen during the call if we omit this,
+ // but we want Interface() and other operations to fail early.
+ methodReceiver(op, fv.rcvr, fv.method)
+
+ return Value{funcType, unsafe.Pointer(fv), v.flag&flagRO | flag(Func)<<flagKindShift}
+}
+
+// methodValueCall is an assembly function that is the code half of
+// the function returned from makeMethodValue. It expects a *methodValue
+// as its context register, and its job is to invoke callMethod(ctxt, frame)
+// where ctxt is the context register and frame is a pointer to the first
+// word in the passed-in argument frame.
+func methodValueCall()
diff --git a/src/pkg/reflect/value.go b/src/pkg/reflect/value.go
index c87812c..5a37204 100644
--- a/src/pkg/reflect/value.go
+++ b/src/pkg/reflect/value.go
@@ -249,7 +249,7 @@
panic(&ValueError{methodName(), 0})
}
if f&flagRO != 0 {
- panic(methodName() + " using value obtained using unexported field")
+ panic("reflect: " + methodName() + " using value obtained using unexported field")
}
}
@@ -262,10 +262,10 @@
}
// Assignable if addressable and not read-only.
if f&flagRO != 0 {
- panic(methodName() + " using value obtained using unexported field")
+ panic("reflect: " + methodName() + " using value obtained using unexported field")
}
if f&flagAddr == 0 {
- panic(methodName() + " using unaddressable value")
+ panic("reflect: " + methodName() + " using unaddressable value")
}
}
@@ -358,7 +358,7 @@
return v.call("CallSlice", in)
}
-func (v Value) call(method string, in []Value) []Value {
+func (v Value) call(op string, in []Value) []Value {
// Get function pointer, type.
t := v.typ
var (
@@ -366,36 +366,7 @@
rcvr iword
)
if v.flag&flagMethod != 0 {
- i := int(v.flag) >> flagMethodShift
- if v.typ.Kind() == Interface {
- tt := (*interfaceType)(unsafe.Pointer(v.typ))
- if i < 0 || i >= len(tt.methods) {
- panic("reflect: broken Value")
- }
- m := &tt.methods[i]
- if m.pkgPath != nil {
- panic(method + " of unexported method")
- }
- t = m.typ
- iface := (*nonEmptyInterface)(v.val)
- if iface.itab == nil {
- panic(method + " of method on nil interface value")
- }
- fn = unsafe.Pointer(&iface.itab.fun[i])
- rcvr = iface.word
- } else {
- ut := v.typ.uncommon()
- if ut == nil || i < 0 || i >= len(ut.methods) {
- panic("reflect: broken Value")
- }
- m := &ut.methods[i]
- if m.pkgPath != nil {
- panic(method + " of unexported method")
- }
- fn = unsafe.Pointer(&m.ifn)
- t = m.mtyp
- rcvr = v.iword()
- }
+ t, fn, rcvr = methodReceiver(op, v, int(v.flag)>>flagMethodShift)
} else if v.flag&flagIndir != 0 {
fn = *(*unsafe.Pointer)(v.val)
} else {
@@ -406,7 +377,7 @@
panic("reflect.Value.Call: call of nil function")
}
- isSlice := method == "CallSlice"
+ isSlice := op == "CallSlice"
n := t.NumIn()
if isSlice {
if !t.IsVariadic() {
@@ -431,12 +402,12 @@
}
for _, x := range in {
if x.Kind() == Invalid {
- panic("reflect: " + method + " using zero Value argument")
+ panic("reflect: " + op + " using zero Value argument")
}
}
for i := 0; i < n; i++ {
if xt, targ := in[i].Type(), t.In(i); !xt.AssignableTo(targ) {
- panic("reflect: " + method + " using " + xt.String() + " as type " + targ.String())
+ panic("reflect: " + op + " using " + xt.String() + " as type " + targ.String())
}
}
if !isSlice && t.IsVariadic() {
@@ -447,7 +418,7 @@
for i := 0; i < m; i++ {
x := in[n+i]
if xt := x.Type(); !xt.AssignableTo(elem) {
- panic("reflect: cannot use " + xt.String() + " as type " + elem.String() + " in " + method)
+ panic("reflect: cannot use " + xt.String() + " as type " + elem.String() + " in " + op)
}
slice.Index(i).Set(x)
}
@@ -467,40 +438,11 @@
// This computation is 5g/6g/8g-dependent
// and probably wrong for gccgo, but so
// is most of this function.
- size := uintptr(0)
- if v.flag&flagMethod != 0 {
- // extra word for receiver interface word
- size += ptrSize
- }
- for i := 0; i < nin; i++ {
- tv := t.In(i)
- a := uintptr(tv.Align())
- size = (size + a - 1) &^ (a - 1)
- size += tv.Size()
- }
- size = (size + ptrSize - 1) &^ (ptrSize - 1)
- for i := 0; i < nout; i++ {
- tv := t.Out(i)
- a := uintptr(tv.Align())
- size = (size + a - 1) &^ (a - 1)
- size += tv.Size()
- }
-
- // size must be > 0 in order for &args[0] to be valid.
- // the argument copying is going to round it up to
- // a multiple of ptrSize anyway, so make it ptrSize to begin with.
- if size < ptrSize {
- size = ptrSize
- }
-
- // round to pointer size
- size = (size + ptrSize - 1) &^ (ptrSize - 1)
+ size, _, _, _ := frameSize(t, v.flag&flagMethod != 0)
// Copy into args.
//
- // TODO(rsc): revisit when reference counting happens.
- // The values are holding up the in references for us,
- // but something must be done for the out references.
+ // TODO(rsc): This will need to be updated for any new garbage collector.
// For now make everything look like a pointer by allocating
// a []unsafe.Pointer.
args := make([]unsafe.Pointer, size/ptrSize)
@@ -616,6 +558,119 @@
}
}
+// methodReceiver returns information about the receiver
+// described by v. The Value v may or may not have the
+// flagMethod bit set, so the kind cached in v.flag should
+// not be used.
+func methodReceiver(op string, v Value, methodIndex int) (t *rtype, fn unsafe.Pointer, rcvr iword) {
+ i := methodIndex
+ if v.typ.Kind() == Interface {
+ tt := (*interfaceType)(unsafe.Pointer(v.typ))
+ if i < 0 || i >= len(tt.methods) {
+ panic("reflect: internal error: invalid method index")
+ }
+ m := &tt.methods[i]
+ if m.pkgPath != nil {
+ panic("reflect: " + op + " of unexported method")
+ }
+ t = m.typ
+ iface := (*nonEmptyInterface)(v.val)
+ if iface.itab == nil {
+ panic("reflect: " + op + " of method on nil interface value")
+ }
+ fn = unsafe.Pointer(&iface.itab.fun[i])
+ rcvr = iface.word
+ } else {
+ ut := v.typ.uncommon()
+ if ut == nil || i < 0 || i >= len(ut.methods) {
+ panic("reflect: internal error: invalid method index")
+ }
+ m := &ut.methods[i]
+ if m.pkgPath != nil {
+ panic("reflect: " + op + " of unexported method")
+ }
+ fn = unsafe.Pointer(&m.ifn)
+ t = m.mtyp
+ rcvr = v.iword()
+ }
+ return
+}
+
+// align returns the result of rounding x up to a multiple of n.
+// n must be a power of two.
+func align(x, n uintptr) uintptr {
+ return (x + n - 1) &^ (n - 1)
+}
+
+// frameSize returns the sizes of the argument and result frame
+// for a function of the given type. The rcvr bool specifies whether
+// a one-word receiver should be included in the total.
+func frameSize(t *rtype, rcvr bool) (total, in, outOffset, out uintptr) {
+ if rcvr {
+ // extra word for receiver interface word
+ total += ptrSize
+ }
+
+ nin := t.NumIn()
+ in = -total
+ for i := 0; i < nin; i++ {
+ tv := t.In(i)
+ total = align(total, uintptr(tv.Align()))
+ total += tv.Size()
+ }
+ in += total
+ total = align(total, ptrSize)
+ nout := t.NumOut()
+ outOffset = total
+ out = -total
+ for i := 0; i < nout; i++ {
+ tv := t.Out(i)
+ total = align(total, uintptr(tv.Align()))
+ total += tv.Size()
+ }
+ out += total
+
+ // total must be > 0 in order for &args[0] to be valid.
+ // the argument copying is going to round it up to
+ // a multiple of ptrSize anyway, so make it ptrSize to begin with.
+ if total < ptrSize {
+ total = ptrSize
+ }
+
+ // round to pointer
+ total = align(total, ptrSize)
+
+ return
+}
+
+// callMethod is the call implementation used by a function returned
+// by makeMethodValue (used by v.Method(i).Interface()).
+// It is a streamlined version of the usual reflect call: the caller has
+// already laid out the argument frame for us, so we don't have
+// to deal with individual Values for each argument.
+// It is in this file so that it can be next to the two similar functions above.
+// The remainder of the makeMethodValue implementation is in makefunc.go.
+func callMethod(ctxt *methodValue, frame unsafe.Pointer) {
+ t, fn, rcvr := methodReceiver("call", ctxt.rcvr, ctxt.method)
+ total, in, outOffset, out := frameSize(t, true)
+
+ // Copy into args.
+ //
+ // TODO(rsc): This will need to be updated for any new garbage collector.
+ // For now make everything look like a pointer by allocating
+ // a []unsafe.Pointer.
+ args := make([]unsafe.Pointer, total/ptrSize)
+ args[0] = unsafe.Pointer(rcvr)
+ base := unsafe.Pointer(&args[0])
+ memmove(unsafe.Pointer(uintptr(base)+ptrSize), frame, in)
+
+ // Call.
+ call(fn, unsafe.Pointer(&args[0]), uint32(total))
+
+ // Copy return values.
+ memmove(unsafe.Pointer(uintptr(frame)+outOffset-ptrSize), unsafe.Pointer(uintptr(base)+outOffset), out)
+}
+
// funcName returns the name of f, for use in error messages.
func funcName(f func([]Value) []Value) string {
pc := *(*uintptr)(unsafe.Pointer(&f))
@@ -902,7 +957,7 @@
if v.flag == 0 {
panic(&ValueError{"reflect.Value.CanInterface", Invalid})
}
- return v.flag&(flagMethod|flagRO) == 0
+ return v.flag&flagRO == 0
}
// Interface returns v's current value as an interface{}.
@@ -921,16 +976,15 @@
if v.flag == 0 {
panic(&ValueError{"reflect.Value.Interface", 0})
}
- if v.flag&flagMethod != 0 {
- panic("reflect.Value.Interface: cannot create interface value for method with bound receiver")
- }
-
if safe && v.flag&flagRO != 0 {
// Do not allow access to unexported values via Interface,
// because they might be pointers that should not be
// writable or methods or function that should not be callable.
panic("reflect.Value.Interface: cannot return value obtained from unexported field or method")
}
+ if v.flag&flagMethod != 0 {
+ v = makeMethodValue("Interface", v)
+ }
k := v.kind()
if k == Interface {
@@ -981,7 +1035,7 @@
switch k {
case Chan, Func, Map, Ptr:
if v.flag&flagMethod != 0 {
- panic("reflect: IsNil of method Value")
+ return false
}
ptr := v.val
if v.flag&flagIndir != 0 {
@@ -1100,7 +1154,7 @@
// Method returns a function value corresponding to v's i'th method.
// The arguments to a Call on the returned function should not include
// a receiver; the returned function will always use v as the receiver.
-// Method panics if i is out of range.
+// Method panics if i is out of range or if v is a nil interface value.
func (v Value) Method(i int) Value {
if v.typ == nil {
panic(&ValueError{"reflect.Value.Method", Invalid})
@@ -1108,7 +1162,10 @@
if v.flag&flagMethod != 0 || i < 0 || i >= v.typ.NumMethod() {
panic("reflect: Method index out of range")
}
- fl := v.flag & (flagRO | flagAddr | flagIndir)
+ if v.typ.Kind() == Interface && v.IsNil() {
+ panic("reflect: Method on nil interface value")
+ }
+ fl := v.flag & (flagRO | flagIndir)
fl |= flag(Func) << flagKindShift
fl |= flag(i)<<flagMethodShift | flagMethod
return Value{v.typ, v.val, fl}
@@ -1232,7 +1289,14 @@
return uintptr(p)
case Func:
if v.flag&flagMethod != 0 {
- panic("reflect.Value.Pointer of method Value")
+ // As the doc comment says, the returned pointer is an
+ // underlying code pointer but not necessarily enough to
+ // identify a single function uniquely. All method expressions
+ // created via reflect have the same underlying code pointer,
+ // so their Pointers are equal. The function used here must
+ // match the one used in makeMethodValue.
+ f := methodValueCall
+ return **(**uintptr)(unsafe.Pointer(&f))
}
p := v.val
if v.flag&flagIndir != 0 {
@@ -1267,7 +1331,7 @@
func (v Value) recv(nb bool) (val Value, ok bool) {
tt := (*chanType)(unsafe.Pointer(v.typ))
if ChanDir(tt.dir)&RecvDir == 0 {
- panic("recv on send-only channel")
+ panic("reflect: recv on send-only channel")
}
word, selected, ok := chanrecv(v.typ, v.iword(), nb)
if selected {
@@ -1295,7 +1359,7 @@
func (v Value) send(x Value, nb bool) (selected bool) {
tt := (*chanType)(unsafe.Pointer(v.typ))
if ChanDir(tt.dir)&SendDir == 0 {
- panic("send on recv-only channel")
+ panic("reflect: send on recv-only channel")
}
x.mustBeExported()
x = x.assignTo("reflect.Value.Send", tt.elem, nil)
@@ -1578,7 +1642,7 @@
// Method on interface.
tt := (*interfaceType)(unsafe.Pointer(v.typ))
if i < 0 || i >= len(tt.methods) {
- panic("reflect: broken Value")
+ panic("reflect: internal error: invalid method index")
}
m := &tt.methods[i]
return m.typ
@@ -1586,7 +1650,7 @@
// Method on concrete type.
ut := v.typ.uncommon()
if ut == nil || i < 0 || i >= len(ut.methods) {
- panic("reflect: broken Value")
+ panic("reflect: internal error: invalid method index")
}
m := &ut.methods[i]
return m.mtyp
@@ -2030,7 +2094,7 @@
// For a conversion to an interface type, target is a suggested scratch space to use.
func (v Value) assignTo(context string, dst *rtype, target *interface{}) Value {
if v.flag&flagMethod != 0 {
- panic(context + ": cannot assign method value to type " + dst.String())
+ v = makeMethodValue(context, v)
}
switch {
@@ -2064,7 +2128,7 @@
// of the value v to type t, Convert panics.
func (v Value) Convert(t Type) Value {
if v.flag&flagMethod != 0 {
- panic("reflect.Value.Convert: cannot convert method values")
+ v = makeMethodValue("Convert", v)
}
op := convertOp(t.common(), v.typ)
if op == nil {
