Imported Upstream version 1.1~hg20130304upstream/1.1_hg20130304

1 files changed, 67 insertions, 0 deletions

diff --git a/src/pkg/reflect/makefunc.go b/src/pkg/reflect/makefunc.go
new file mode 100644
index 000000000..024f938f1
--- /dev/null
+++ b/src/pkg/reflect/makefunc.go
@@ -0,0 +1,67 @@
+// Copyright 2012 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.
+
+// MakeFunc implementation.
+
+package reflect
+
+import (
+	"unsafe"
+)
+
+// makeFuncImpl is the closure value implementing the function
+// returned by MakeFunc.
+type makeFuncImpl struct {
+	code uintptr
+	typ  *funcType
+	fn   func([]Value) []Value
+}
+
+// MakeFunc returns a new function of the given Type
+// that wraps the function fn. When called, that new function
+// does the following:
+//
+//	- converts its arguments to a list of Values args.
+//	- runs results := fn(args).
+//	- returns the results as a slice of Values, one per formal result.
+//
+// The implementation fn can assume that the argument Value slice
+// has the number and type of arguments given by typ.
+// If typ describes a variadic function, the final Value is itself
+// a slice representing the variadic arguments, as in the
+// body of a variadic function. The result Value slice returned by fn
+// must have the number and type of results given by typ.
+//
+// The Value.Call method allows the caller to invoke a typed function
+// in terms of Values; in contrast, MakeFunc allows the caller to implement
+// a typed function in terms of Values.
+//
+// The Examples section of the documentation includes an illustration
+// of how to use MakeFunc to build a swap function for different types.
+//
+func MakeFunc(typ Type, fn func(args []Value) (results []Value)) Value {
+	if typ.Kind() != Func {
+		panic("reflect: call of MakeFunc with non-Func type")
+	}
+
+	t := typ.common()
+	ftyp := (*funcType)(unsafe.Pointer(t))
+
+	// indirect Go func value (dummy) to obtain
+	// actual code address. (A Go func is a pointer
+	// to a C function pointer. http://golang.org/s/go11func.)
+	dummy := makeFuncStub
+	code := **(**uintptr)(unsafe.Pointer(&dummy))
+
+	impl := &makeFuncImpl{code: code, typ: ftyp, fn: fn}
+
+	return Value{t, unsafe.Pointer(impl), flag(Func) << flagKindShift}
+}
+
+// makeFuncStub is an assembly function that is the code half of
+// the function returned from MakeFunc. It expects a *callReflectFunc
+// as its context register, and its job is to invoke callReflect(ctxt, frame)
+// where ctxt is the context register and frame is a pointer to the first
+// word in the passed-in argument frame.
+func makeFuncStub()