Golang Type.Elem方法代码示例

func needWrapType(typ types.Type) bool {
	switch typ := typ.(type) {
	case *types.Basic:
		return false
	case *types.Struct:
		return true
	case *types.Named:
		switch ut := typ.Underlying().(type) {
		case *types.Basic:
			return false
		default:
			return needWrapType(ut)
		}
	case *types.Array:
		return true
	case *types.Map:
		return true
	case *types.Slice:
		return true
	case *types.Interface:
		wrap := true
		if typ.Underlying() == universe.syms["error"].GoType().Underlying() {
			wrap = false
		}
		return wrap
	case *types.Signature:
		return true
	case *types.Pointer:
		return needWrapType(typ.Elem())
	}
	return false
}

func (f Field) UnderlyingTarget() fieldser {
	var t types.Type
	switch v := f.v.Type().(type) {
	case elemer:
		t = v.Elem()
	case *types.Named:
		t = v
	}
	if _, ok := t.(underlyinger); !ok {
		return nil
	}
	u := t.(underlyinger).Underlying()
	switch t := u.(type) {
	case *types.Struct:
		return fields{
			g:      f.gen,
			target: t,
		}
	case *types.Pointer:
		return fields{
			g:      f.gen,
			target: t.Elem().(*types.Named).Underlying().(*types.Struct),
		}
	}
	return nil
}

// MethodSet returns the method set of type T.  It is thread-safe.
//
// If cache is nil, this function is equivalent to types.NewMethodSet(T).
// Utility functions can thus expose an optional *MethodSetCache
// parameter to clients that care about performance.
//
func (cache *MethodSetCache) MethodSet(T types.Type) *types.MethodSet {
	if cache == nil {
		return types.NewMethodSet(T)
	}
	cache.mu.Lock()
	defer cache.mu.Unlock()

	switch T := T.(type) {
	case *types.Named:
		return cache.lookupNamed(T).value

	case *types.Pointer:
		if N, ok := T.Elem().(*types.Named); ok {
			return cache.lookupNamed(N).pointer
		}
	}

	// all other types
	// (The map uses pointer equivalence, not type identity.)
	mset := cache.others[T]
	if mset == nil {
		mset = types.NewMethodSet(T)
		if cache.others == nil {
			cache.others = make(map[types.Type]*types.MethodSet)
		}
		cache.others[T] = mset
	}
	return mset
}

// isSupported returns whether the generators can handle the type.
func (g *generator) isSupported(t types.Type) bool {
	if isErrorType(t) {
		return true
	}
	switch t := t.(type) {
	case *types.Basic:
		return true
	case *types.Slice:
		switch e := t.Elem().(type) {
		case *types.Basic:
			return e.Kind() == types.Uint8
		}
	case *types.Pointer:
		switch t := t.Elem().(type) {
		case *types.Named:
			return g.validPkg(t.Obj().Pkg())
		}
	case *types.Named:
		switch t.Underlying().(type) {
		case *types.Interface, *types.Pointer:
			return g.validPkg(t.Obj().Pkg())
		}
	}
	return false
}

// cgoType returns the name of a Cgo type suitable for converting a value of
// the given type.
func (g *generator) cgoType(t types.Type) string {
	if isErrorType(t) {
		return g.cgoType(types.Typ[types.String])
	}
	switch t := t.(type) {
	case *types.Basic:
		switch t.Kind() {
		case types.Bool, types.UntypedBool:
			return "char"
		case types.Int:
			return "nint"
		case types.Int8:
			return "int8_t"
		case types.Int16:
			return "int16_t"
		case types.Int32, types.UntypedRune: // types.Rune
			return "int32_t"
		case types.Int64, types.UntypedInt:
			return "int64_t"
		case types.Uint8: // types.Byte
			return "uint8_t"
		// TODO(crawshaw): case types.Uint, types.Uint16, types.Uint32, types.Uint64:
		case types.Float32:
			return "float"
		case types.Float64, types.UntypedFloat:
			return "double"
		case types.String:
			return "nstring"
		default:
			g.errorf("unsupported basic type: %s", t)
		}
	case *types.Slice:
		switch e := t.Elem().(type) {
		case *types.Basic:
			switch e.Kind() {
			case types.Uint8: // Byte.
				return "nbyteslice"
			default:
				g.errorf("unsupported slice type: %s", t)
			}
		default:
			g.errorf("unsupported slice type: %s", t)
		}
	case *types.Pointer:
		if _, ok := t.Elem().(*types.Named); ok {
			return g.cgoType(t.Elem())
		}
		g.errorf("unsupported pointer to type: %s", t)
	case *types.Named:
		return "int32_t"
	default:
		g.errorf("unsupported type: %s", t)
	}
	return "TODO"
}

func (g *goGen) genWrite(toVar, fromVar string, t types.Type, mode varMode) {
	if isErrorType(t) {
		g.Printf("var %s_str string\n", toVar)
		g.Printf("if %s == nil {\n", fromVar)
		g.Printf("    %s_str = \"\"\n", toVar)
		g.Printf("} else {\n")
		g.Printf("    %s_str = %s.Error()\n", toVar, fromVar)
		g.Printf("}\n")
		g.genWrite(toVar, toVar+"_str", types.Typ[types.String], mode)
		return
	}
	switch t := t.(type) {
	case *types.Basic:
		switch t.Kind() {
		case types.String:
			g.Printf("%s := encodeString(%s)\n", toVar, fromVar)
		case types.Bool:
			g.Printf("var %s C.%s = 0\n", toVar, g.cgoType(t))
			g.Printf("if %s { %s = 1 }\n", fromVar, toVar)
		default:
			g.Printf("%s := C.%s(%s)\n", toVar, g.cgoType(t), fromVar)
		}
	case *types.Slice:
		switch e := t.Elem().(type) {
		case *types.Basic:
			switch e.Kind() {
			case types.Uint8: // Byte.
				g.Printf("%s := fromSlice(%s, %v)\n", toVar, fromVar, mode == modeRetained)
			default:
				g.errorf("unsupported type: %s", t)
			}
		default:
			g.errorf("unsupported type: %s", t)
		}
	case *types.Pointer:
		// TODO(crawshaw): test *int
		// TODO(crawshaw): test **Generator
		switch t := t.Elem().(type) {
		case *types.Named:
			g.genToRefNum(toVar, fromVar)
		default:
			g.errorf("unsupported type %s", t)
		}
	case *types.Named:
		switch u := t.Underlying().(type) {
		case *types.Interface, *types.Pointer:
			g.genToRefNum(toVar, fromVar)
		default:
			g.errorf("unsupported, direct named type %s: %s", t, u)
		}
	default:
		g.errorf("unsupported type %s", t)
	}
}

// jniType returns a string that can be used as a JNI type.
func (g *javaGen) jniType(T types.Type) string {
	if isErrorType(T) {
		// The error type is usually translated into an exception in
		// Java, however the type can be exposed in other ways, such
		// as an exported field.
		return g.jniType(types.Typ[types.String])
	}
	switch T := T.(type) {
	case *types.Basic:
		switch T.Kind() {
		case types.Bool, types.UntypedBool:
			return "jboolean"
		case types.Int:
			return "jlong"
		case types.Int8:
			return "jbyte"
		case types.Int16:
			return "jshort"
		case types.Int32, types.UntypedRune: // types.Rune
			return "jint"
		case types.Int64, types.UntypedInt:
			return "jlong"
		case types.Uint8: // types.Byte
			// TODO(crawshaw): Java bytes are signed, so this is
			// questionable, but vital.
			return "jbyte"
		// TODO(crawshaw): case types.Uint, types.Uint16, types.Uint32, types.Uint64:
		case types.Float32:
			return "jfloat"
		case types.Float64, types.UntypedFloat:
			return "jdouble"
		case types.String, types.UntypedString:
			return "jstring"
		default:
			g.errorf("unsupported basic type: %s", T)
			return "TODO"
		}
	case *types.Slice:
		return "jbyteArray"

	case *types.Pointer:
		if _, ok := T.Elem().(*types.Named); ok {
			return g.jniType(T.Elem())
		}
		g.errorf("unsupported pointer to type: %s", T)
	case *types.Named:
		return "jobject"
	default:
		g.errorf("unsupported jniType: %#+v, %s\n", T, T)
	}
	return "TODO"
}

func isExported(t types.Type) bool {
	if isErrorType(t) {
		return true
	}
	switch t := t.(type) {
	case *types.Basic:
		return true
	case *types.Named:
		return t.Obj().Exported()
	case *types.Pointer:
		return isExported(t.Elem())
	default:
		return true
	}
}

func (g *goGen) genWrite(valName, seqName string, T types.Type) {
	if isErrorType(T) {
		g.Printf("if %s == nil {\n", valName)
		g.Printf("    %s.WriteString(\"\");\n", seqName)
		g.Printf("} else {\n")
		g.Printf("    %s.WriteString(%s.Error());\n", seqName, valName)
		g.Printf("}\n")
		return
	}
	switch T := T.(type) {
	case *types.Pointer:
		// TODO(crawshaw): test *int
		// TODO(crawshaw): test **Generator
		switch T := T.Elem().(type) {
		case *types.Named:
			obj := T.Obj()
			if obj.Pkg() != g.pkg {
				g.errorf("type %s not defined in package %s", T, g.pkg)
				return
			}
			g.Printf("%s.WriteGoRef(%s)\n", seqName, valName)
		default:
			g.errorf("unsupported type %s", T)
		}
	case *types.Named:
		switch u := T.Underlying().(type) {
		case *types.Interface, *types.Pointer:
			g.Printf("%s.WriteGoRef(%s)\n", seqName, valName)
		default:
			g.errorf("unsupported, direct named type %s: %s", T, u)
		}
	default:
		g.Printf("%s.Write%s(%s);\n", seqName, seqType(T), valName)
	}
}

func (g *javaGen) genRead(resName, seqName string, T types.Type) {
	switch T := T.(type) {
	case *types.Pointer:
		// TODO(crawshaw): test *int
		// TODO(crawshaw): test **Generator
		switch T := T.Elem().(type) {
		case *types.Named:
			o := T.Obj()
			if o.Pkg() != g.pkg {
				g.errorf("type %s not defined in %s", T, g.pkg)
				return
			}
			g.Printf("%s = new %s(%s.readRef());\n", resName, o.Name(), seqName)
		default:
			g.errorf("unsupported type %s", T)
		}
	case *types.Named:
		switch T.Underlying().(type) {
		case *types.Interface, *types.Pointer:
			o := T.Obj()
			if o.Pkg() != g.pkg {
				g.errorf("type %s not defined in %s", T, g.pkg)
				return
			}
			g.Printf("%s = new %s.Proxy(%s.readRef());\n", resName, o.Name(), seqName)
		default:
			g.errorf("unsupported, direct named type %s", T)
		}
	default:
		g.Printf("%s = %s.read%s();\n", resName, seqName, seqType(T))
	}
}

func (g *ObjcGen) genWrite(varName string, t types.Type, mode varMode) {
	switch t := t.(type) {
	case *types.Basic:
		switch t.Kind() {
		case types.String:
			g.Printf("nstring _%s = go_seq_from_objc_string(%s);\n", varName, varName)
		default:
			g.Printf("%s _%s = (%s)%s;\n", g.cgoType(t), varName, g.cgoType(t), varName)
		}
	case *types.Slice:
		switch e := t.Elem().(type) {
		case *types.Basic:
			switch e.Kind() {
			case types.Uint8: // Byte.
				g.Printf("nbyteslice _%s = go_seq_from_objc_bytearray(%s, %d);\n", varName, varName, toCFlag(mode == modeRetained))
			default:
				g.errorf("unsupported type: %s", t)
			}
		default:
			g.errorf("unsupported type: %s", t)
		}
	case *types.Named:
		switch u := t.Underlying().(type) {
		case *types.Interface:
			g.genRefWrite(varName)
		default:
			g.errorf("unsupported named type: %s / %T", u, u)
		}
	case *types.Pointer:
		g.genRefWrite(varName)
	default:
		g.Printf("%s _%s = (%s)%s;\n", g.cgoType(t), varName, g.cgoType(t), varName)
	}
}

func (g *javaGen) genCToJava(toName, fromName string, t types.Type, mode varMode) {
	if isErrorType(t) {
		g.genCToJava(toName, fromName, types.Typ[types.String], mode)
		return
	}
	switch t := t.(type) {
	case *types.Basic:
		switch t.Kind() {
		case types.String:
			g.Printf("jstring %s = go_seq_to_java_string(env, %s);\n", toName, fromName)
		case types.Bool:
			g.Printf("jboolean %s = %s ? JNI_TRUE : JNI_FALSE;\n", toName, fromName)
		default:
			g.Printf("%s %s = (%s)%s;\n", g.jniType(t), toName, g.jniType(t), fromName)
		}
	case *types.Slice:
		switch e := t.Elem().(type) {
		case *types.Basic:
			switch e.Kind() {
			case types.Uint8: // Byte.
				g.Printf("jbyteArray %s = go_seq_to_java_bytearray(env, %s, %d);\n", toName, fromName, g.toCFlag(mode == modeRetained))
			default:
				g.errorf("unsupported type: %s", t)
			}
		default:
			g.errorf("unsupported type: %s", t)
		}
	case *types.Pointer:
		// TODO(crawshaw): test *int
		// TODO(crawshaw): test **Generator
		switch t := t.Elem().(type) {
		case *types.Named:
			g.genFromRefnum(toName, fromName, t, t.Obj())
		default:
			g.errorf("unsupported type %s", t)
		}
	case *types.Named:
		switch t.Underlying().(type) {
		case *types.Interface, *types.Pointer:
			g.genFromRefnum(toName, fromName, t, t.Obj())
		default:
			g.errorf("unsupported, direct named type %s", t)
		}
	default:
		g.Printf("%s %s = (%s)%s;\n", g.jniType(t), toName, g.jniType(t), fromName)
	}
}

// jniType returns a string that can be used as a JNI type.
func (g *JavaGen) jniType(T types.Type) string {
	switch T := T.(type) {
	case *types.Basic:
		switch T.Kind() {
		case types.Bool, types.UntypedBool:
			return "jboolean"
		case types.Int:
			return "jlong"
		case types.Int8:
			return "jbyte"
		case types.Int16:
			return "jshort"
		case types.Int32, types.UntypedRune: // types.Rune
			return "jint"
		case types.Int64, types.UntypedInt:
			return "jlong"
		case types.Uint8: // types.Byte
			// TODO(crawshaw): Java bytes are signed, so this is
			// questionable, but vital.
			return "jbyte"
		// TODO(crawshaw): case types.Uint, types.Uint16, types.Uint32, types.Uint64:
		case types.Float32:
			return "jfloat"
		case types.Float64, types.UntypedFloat:
			return "jdouble"
		case types.String, types.UntypedString:
			return "jstring"
		default:
			g.errorf("unsupported basic type: %s", T)
			return "TODO"
		}
	case *types.Slice:
		return "jbyteArray"

	case *types.Pointer:
		if _, ok := T.Elem().(*types.Named); ok {
			return g.jniType(T.Elem())
		}
		g.errorf("unsupported pointer to type: %s", T)
	case *types.Named:
		return "jobject"
	default:
		g.errorf("unsupported jniType: %#+v, %s\n", T, T)
	}
	return "TODO"
}

func (g *objcGen) genRead(toName, fromName string, t types.Type, mode varMode) {
	if isErrorType(t) {
		g.genRead(toName, fromName, types.Typ[types.String], mode)
		return
	}
	switch t := t.(type) {
	case *types.Basic:
		switch t.Kind() {
		case types.String:
			g.Printf("NSString *%s = go_seq_to_objc_string(%s);\n", toName, fromName)
		case types.Bool:
			g.Printf("BOOL %s = %s ? YES : NO;\n", toName, fromName)
		default:
			g.Printf("%s %s = (%s)%s;\n", g.objcType(t), toName, g.objcType(t), fromName)
		}
	case *types.Slice:
		switch e := t.Elem().(type) {
		case *types.Basic:
			switch e.Kind() {
			case types.Uint8: // Byte.
				g.Printf("NSData *%s = go_seq_to_objc_bytearray(%s, %d);\n", toName, fromName, g.toCFlag(mode == modeRetained))
			default:
				g.errorf("unsupported type: %s", t)
			}
		default:
			g.errorf("unsupported type: %s", t)
		}
	case *types.Pointer:
		switch t := t.Elem().(type) {
		case *types.Named:
			g.genRefRead(toName, fromName, types.NewPointer(t))
		default:
			g.errorf("unsupported type %s", t)
		}
	case *types.Named:
		switch t.Underlying().(type) {
		case *types.Interface, *types.Pointer:
			g.genRefRead(toName, fromName, t)
		default:
			g.errorf("unsupported, direct named type %s", t)
		}
	default:
		g.Printf("%s %s = (%s)%s;\n", g.objcType(t), toName, g.objcType(t), fromName)
	}
}

// store stores value v of type T into *addr.
func store(T types.Type, addr *value, v value) {
	switch T := T.Underlying().(type) {
	case *types.Struct:
		lhs := (*addr).(structure)
		rhs := v.(structure)
		for i := range lhs {
			store(T.Field(i).Type(), &lhs[i], rhs[i])
		}
	case *types.Array:
		lhs := (*addr).(array)
		rhs := v.(array)
		for i := range lhs {
			store(T.Elem(), &lhs[i], rhs[i])
		}
	default:
		*addr = v
	}
}