reflect: add Type.Implements, Type.AssignableTo, Value.CallSlice; make Set match Go
This CL makes reflect require that values be assignable to the target type
in exactly the same places where that is the rule in Go. It also adds
the Implements and AssignableTo methods so that callers can check
the types themselves so as to avoid a panic.
Before this CL, reflect required strict type identity.
This CL expands Call to accept and correctly marshal arbitrary
argument lists for variadic functions; it introduces CallSlice for use
in the case where the slice for the variadic argument is already known.
Fixes #327.
Fixes #1212.
R=r, dsymonds
CC=golang-dev
https://golang.org/cl/4439058
diff --git a/src/pkg/reflect/set_test.go b/src/pkg/reflect/set_test.go
new file mode 100644
index 0000000..862d4c5
--- /dev/null
+++ b/src/pkg/reflect/set_test.go
@@ -0,0 +1,211 @@
+// Copyright 2011 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 reflect_test
+
+import (
+ "bytes"
+ "go/ast"
+ "io"
+ . "reflect"
+ "testing"
+ "unsafe"
+)
+
+type MyBuffer bytes.Buffer
+
+func TestImplicitMapConversion(t *testing.T) {
+ // Test implicit conversions in MapIndex and SetMapIndex.
+ {
+ // direct
+ m := make(map[int]int)
+ mv := NewValue(m)
+ mv.SetMapIndex(NewValue(1), NewValue(2))
+ x, ok := m[1]
+ if x != 2 {
+ t.Errorf("#1 after SetMapIndex(1,2): %d, %t (map=%v)", x, ok, m)
+ }
+ if n := mv.MapIndex(NewValue(1)).Interface().(int); n != 2 {
+ t.Errorf("#1 MapIndex(1) = %d", n)
+ }
+ }
+ {
+ // convert interface key
+ m := make(map[interface{}]int)
+ mv := NewValue(m)
+ mv.SetMapIndex(NewValue(1), NewValue(2))
+ x, ok := m[1]
+ if x != 2 {
+ t.Errorf("#2 after SetMapIndex(1,2): %d, %t (map=%v)", x, ok, m)
+ }
+ if n := mv.MapIndex(NewValue(1)).Interface().(int); n != 2 {
+ t.Errorf("#2 MapIndex(1) = %d", n)
+ }
+ }
+ {
+ // convert interface value
+ m := make(map[int]interface{})
+ mv := NewValue(m)
+ mv.SetMapIndex(NewValue(1), NewValue(2))
+ x, ok := m[1]
+ if x != 2 {
+ t.Errorf("#3 after SetMapIndex(1,2): %d, %t (map=%v)", x, ok, m)
+ }
+ if n := mv.MapIndex(NewValue(1)).Interface().(int); n != 2 {
+ t.Errorf("#3 MapIndex(1) = %d", n)
+ }
+ }
+ {
+ // convert both interface key and interface value
+ m := make(map[interface{}]interface{})
+ mv := NewValue(m)
+ mv.SetMapIndex(NewValue(1), NewValue(2))
+ x, ok := m[1]
+ if x != 2 {
+ t.Errorf("#4 after SetMapIndex(1,2): %d, %t (map=%v)", x, ok, m)
+ }
+ if n := mv.MapIndex(NewValue(1)).Interface().(int); n != 2 {
+ t.Errorf("#4 MapIndex(1) = %d", n)
+ }
+ }
+ {
+ // convert both, with non-empty interfaces
+ m := make(map[io.Reader]io.Writer)
+ mv := NewValue(m)
+ b1 := new(bytes.Buffer)
+ b2 := new(bytes.Buffer)
+ mv.SetMapIndex(NewValue(b1), NewValue(b2))
+ x, ok := m[b1]
+ if x != b2 {
+ t.Errorf("#5 after SetMapIndex(b1, b2): %p (!= %p), %t (map=%v)", x, b2, ok, m)
+ }
+ if p := mv.MapIndex(NewValue(b1)).Elem().Pointer(); p != uintptr(unsafe.Pointer(b2)) {
+ t.Errorf("#5 MapIndex(b1) = %p want %p", p, b2)
+ }
+ }
+ {
+ // convert channel direction
+ m := make(map[<-chan int]chan int)
+ mv := NewValue(m)
+ c1 := make(chan int)
+ c2 := make(chan int)
+ mv.SetMapIndex(NewValue(c1), NewValue(c2))
+ x, ok := m[c1]
+ if x != c2 {
+ t.Errorf("#6 after SetMapIndex(c1, c2): %p (!= %p), %t (map=%v)", x, c2, ok, m)
+ }
+ if p := mv.MapIndex(NewValue(c1)).Pointer(); p != NewValue(c2).Pointer() {
+ t.Errorf("#6 MapIndex(c1) = %p want %p", p, c2)
+ }
+ }
+ {
+ // convert identical underlying types
+ // TODO(rsc): Should be able to define MyBuffer here.
+ // 6l prints very strange messages about .this.Bytes etc
+ // when we do that though, so MyBuffer is defined
+ // at top level.
+ m := make(map[*MyBuffer]*bytes.Buffer)
+ mv := NewValue(m)
+ b1 := new(MyBuffer)
+ b2 := new(bytes.Buffer)
+ mv.SetMapIndex(NewValue(b1), NewValue(b2))
+ x, ok := m[b1]
+ if x != b2 {
+ t.Errorf("#7 after SetMapIndex(b1, b2): %p (!= %p), %t (map=%v)", x, b2, ok, m)
+ }
+ if p := mv.MapIndex(NewValue(b1)).Pointer(); p != uintptr(unsafe.Pointer(b2)) {
+ t.Errorf("#7 MapIndex(b1) = %p want %p", p, b2)
+ }
+ }
+
+}
+
+func TestImplicitSetConversion(t *testing.T) {
+ // Assume TestImplicitMapConversion covered the basics.
+ // Just make sure conversions are being applied at all.
+ var r io.Reader
+ b := new(bytes.Buffer)
+ rv := NewValue(&r).Elem()
+ rv.Set(NewValue(b))
+ if r != b {
+ t.Errorf("after Set: r=%T(%v)", r, r)
+ }
+}
+
+func TestImplicitSendConversion(t *testing.T) {
+ c := make(chan io.Reader, 10)
+ b := new(bytes.Buffer)
+ NewValue(c).Send(NewValue(b))
+ if bb := <-c; bb != b {
+ t.Errorf("Received %p != %p", bb, b)
+ }
+}
+
+func TestImplicitCallConversion(t *testing.T) {
+ // Arguments must be assignable to parameter types.
+ fv := NewValue(io.WriteString)
+ b := new(bytes.Buffer)
+ fv.Call([]Value{NewValue(b), NewValue("hello world")})
+ if b.String() != "hello world" {
+ t.Errorf("After call: string=%q want %q", b.String(), "hello world")
+ }
+}
+
+func TestImplicitAppendConversion(t *testing.T) {
+ // Arguments must be assignable to the slice's element type.
+ s := []io.Reader{}
+ sv := NewValue(&s).Elem()
+ b := new(bytes.Buffer)
+ sv.Set(Append(sv, NewValue(b)))
+ if len(s) != 1 || s[0] != b {
+ t.Errorf("after append: s=%v want [%p]", s, b)
+ }
+}
+
+var implementsTests = []struct {
+ x interface{}
+ t interface{}
+ b bool
+}{
+ {new(*bytes.Buffer), new(io.Reader), true},
+ {new(bytes.Buffer), new(io.Reader), false},
+ {new(*bytes.Buffer), new(io.ReaderAt), false},
+ {new(*ast.Ident), new(ast.Expr), true},
+}
+
+func TestImplements(t *testing.T) {
+ for _, tt := range implementsTests {
+ xv := Typeof(tt.x).Elem()
+ xt := Typeof(tt.t).Elem()
+ if b := xv.Implements(xt); b != tt.b {
+ t.Errorf("(%s).Implements(%s) = %v, want %v", xv.String(), xt.String(), b, tt.b)
+ }
+ }
+}
+
+var assignableTests = []struct {
+ x interface{}
+ t interface{}
+ b bool
+}{
+ {new(chan int), new(<-chan int), true},
+ {new(<-chan int), new(chan int), false},
+ {new(*int), new(IntPtr), true},
+ {new(IntPtr), new(*int), true},
+ {new(IntPtr), new(IntPtr1), false},
+ // test runs implementsTests too
+}
+
+type IntPtr *int
+type IntPtr1 *int
+
+func TestAssignableTo(t *testing.T) {
+ for _, tt := range append(assignableTests, implementsTests...) {
+ xv := Typeof(tt.x).Elem()
+ xt := Typeof(tt.t).Elem()
+ if b := xv.AssignableTo(xt); b != tt.b {
+ t.Errorf("(%s).AssignableTo(%s) = %v, want %v", xv.String(), xt.String(), b, tt.b)
+ }
+ }
+}
