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-rw-r--r--test/interface/convert.go146
1 files changed, 146 insertions, 0 deletions
diff --git a/test/interface/convert.go b/test/interface/convert.go
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+// run
+
+// 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.
+
+// Test all the different interface conversion runtime functions.
+
+package main
+
+type Stringer interface {
+ String() string
+}
+type StringLengther interface {
+ String() string
+ Length() int
+}
+type Empty interface{}
+
+type T string
+
+func (t T) String() string {
+ return string(t)
+}
+func (t T) Length() int {
+ return len(t)
+}
+
+type U string
+
+func (u U) String() string {
+ return string(u)
+}
+
+var t = T("hello")
+var u = U("goodbye")
+var e Empty
+var s Stringer = t
+var sl StringLengther = t
+var i int
+var ok bool
+
+func hello(s string) {
+ if s != "hello" {
+ println("not hello: ", s)
+ panic("fail")
+ }
+}
+
+func five(i int) {
+ if i != 5 {
+ println("not 5: ", i)
+ panic("fail")
+ }
+}
+
+func true(ok bool) {
+ if !ok {
+ panic("not true")
+ }
+}
+
+func false(ok bool) {
+ if ok {
+ panic("not false")
+ }
+}
+
+func main() {
+ // T2I
+ s = t
+ hello(s.String())
+
+ // I2T
+ t = s.(T)
+ hello(t.String())
+
+ // T2E
+ e = t
+
+ // E2T
+ t = e.(T)
+ hello(t.String())
+
+ // T2I again
+ sl = t
+ hello(sl.String())
+ five(sl.Length())
+
+ // I2I static
+ s = sl
+ hello(s.String())
+
+ // I2I dynamic
+ sl = s.(StringLengther)
+ hello(sl.String())
+ five(sl.Length())
+
+ // I2E (and E2T)
+ e = s
+ hello(e.(T).String())
+
+ // E2I
+ s = e.(Stringer)
+ hello(s.String())
+
+ // I2T2 true
+ t, ok = s.(T)
+ true(ok)
+ hello(t.String())
+
+ // I2T2 false
+ _, ok = s.(U)
+ false(ok)
+
+ // I2I2 true
+ sl, ok = s.(StringLengther)
+ true(ok)
+ hello(sl.String())
+ five(sl.Length())
+
+ // I2I2 false (and T2I)
+ s = u
+ sl, ok = s.(StringLengther)
+ false(ok)
+
+ // E2T2 true
+ t, ok = e.(T)
+ true(ok)
+ hello(t.String())
+
+ // E2T2 false
+ i, ok = e.(int)
+ false(ok)
+
+ // E2I2 true
+ sl, ok = e.(StringLengther)
+ true(ok)
+ hello(sl.String())
+ five(sl.Length())
+
+ // E2I2 false (and T2E)
+ e = u
+ sl, ok = e.(StringLengther)
+ false(ok)
+}