Golang types.Type類代碼示例

func (x array) hash(t types.Type) int {
	h := 0
	tElt := t.Underlying().(*types.Array).Elem()
	for _, xi := range x {
		h += hash(tElt, xi)
	}
	return h
}

func (x array) eq(t types.Type, _y interface{}) bool {
	y := _y.(array)
	tElt := t.Underlying().(*types.Array).Elem()
	for i, xi := range x {
		if !equals(tElt, xi, y[i]) {
			return false
		}
	}
	return true
}

func makeImplementsType(T types.Type, fset *token.FileSet) serial.ImplementsType {
	var pos token.Pos
	if nt, ok := deref(T).(*types.Named); ok { // implementsResult.t may be non-named
		pos = nt.Obj().Pos()
	}
	return serial.ImplementsType{
		Name: T.String(),
		Pos:  fset.Position(pos).String(),
		Kind: typeKind(T),
	}
}

// usesBuiltinMap returns true if the built-in hash function and
// equivalence relation for type t are consistent with those of the
// interpreter's representation of type t.  Such types are: all basic
// types (bool, numbers, string), pointers and channels.
//
// usesBuiltinMap returns false for types that require a custom map
// implementation: interfaces, arrays and structs.
//
// Panic ensues if t is an invalid map key type: function, map or slice.
func usesBuiltinMap(t types.Type) bool {
	switch t := t.(type) {
	case *types.Basic, *types.Chan, *types.Pointer:
		return true
	case *types.Named:
		return usesBuiltinMap(t.Underlying())
	case *types.Interface, *types.Array, *types.Struct:
		return false
	}
	panic(fmt.Sprintf("invalid map key type: %T", t))
}

// CanHaveDynamicTypes reports whether the type T can "hold" dynamic types,
// i.e. is an interface (incl. reflect.Type) or a reflect.Value.
//
func CanHaveDynamicTypes(T types.Type) bool {
	switch T := T.(type) {
	case *types.Named:
		if obj := T.Obj(); obj.Name() == "Value" && obj.Pkg().Path() == "reflect" {
			return true // reflect.Value
		}
		return CanHaveDynamicTypes(T.Underlying())
	case *types.Interface:
		return true
	}
	return false
}

// CanPoint reports whether the type T is pointerlike,
// for the purposes of this analysis.
func CanPoint(T types.Type) bool {
	switch T := T.(type) {
	case *types.Named:
		if obj := T.Obj(); obj.Name() == "Value" && obj.Pkg().Path() == "reflect" {
			return true // treat reflect.Value like interface{}
		}
		return CanPoint(T.Underlying())

	case *types.Pointer, *types.Interface, *types.Map, *types.Chan, *types.Signature, *types.Slice:
		return true
	}

	return false // array struct tuple builtin basic
}

// eqnil returns the comparison x == y using the equivalence relation
// appropriate for type t.
// If t is a reference type, at most one of x or y may be a nil value
// of that type.
//
func eqnil(t types.Type, x, y value) bool {
	switch t.Underlying().(type) {
	case *types.Map, *types.Signature, *types.Slice:
		// Since these types don't support comparison,
		// one of the operands must be a literal nil.
		switch x := x.(type) {
		case *hashmap:
			return (x != nil) == (y.(*hashmap) != nil)
		case map[value]value:
			return (x != nil) == (y.(map[value]value) != nil)
		case *ssa.Function:
			switch y := y.(type) {
			case *ssa.Function:
				return (x != nil) == (y != nil)
			case *closure:
				return true
			}
		case *closure:
			return (x != nil) == (y.(*ssa.Function) != nil)
		case []value:
			return (x != nil) == (y.([]value) != nil)
		}
		panic(fmt.Sprintf("eqnil(%s): illegal dynamic type: %T", t, x))
	}

	return equals(t, x, y)
}

func describeType(o *Oracle, qpos *QueryPos, path []ast.Node) (*describeTypeResult, error) {
	var description string
	var t types.Type
	switch n := path[0].(type) {
	case *ast.Ident:
		t = qpos.info.TypeOf(n)
		switch t := t.(type) {
		case *types.Basic:
			description = "reference to built-in "

		case *types.Named:
			isDef := t.Obj().Pos() == n.Pos() // see caveats at isDef above
			if isDef {
				description = "definition of "
			} else {
				description = "reference to "
			}
		}

	case ast.Expr:
		t = qpos.info.TypeOf(n)

	default:
		// Unreachable?
		return nil, fmt.Errorf("unexpected AST for type: %T", n)
	}

	description = description + "type " + qpos.TypeString(t)

	// Show sizes for structs and named types (it's fairly obvious for others).
	switch t.(type) {
	case *types.Named, *types.Struct:
		// TODO(adonovan): use o.imp.Config().TypeChecker.Sizes when
		// we add the Config() method (needs some thought).
		szs := types.StdSizes{8, 8}
		description = fmt.Sprintf("%s (size %d, align %d)", description,
			szs.Sizeof(t), szs.Alignof(t))
	}

	return &describeTypeResult{
		qpos:        qpos,
		node:        path[0],
		description: description,
		typ:         t,
		methods:     accessibleMethods(t, qpos.info.Pkg),
	}, nil
}

// zeroValue emits to f code to produce a zero value of type t,
// and returns it.
//
func zeroValue(f *Function, t types.Type) Value {
	switch t.Underlying().(type) {
	case *types.Struct, *types.Array:
		return emitLoad(f, f.addLocal(t, token.NoPos))
	default:
		return zeroConst(t)
	}
}

// IntuitiveMethodSet returns the intuitive method set of a type, T.
//
// The result contains MethodSet(T) and additionally, if T is a
// concrete type, methods belonging to *T if there is no identically
// named method on T itself.  This corresponds to user intuition about
// method sets; this function is intended only for user interfaces.
//
// The order of the result is as for types.MethodSet(T).
//
func IntuitiveMethodSet(T types.Type, msets *types.MethodSetCache) []*types.Selection {
	var result []*types.Selection
	mset := msets.MethodSet(T)
	if _, ok := T.Underlying().(*types.Interface); ok {
		for i, n := 0, mset.Len(); i < n; i++ {
			result = append(result, mset.At(i))
		}
	} else {
		pmset := msets.MethodSet(types.NewPointer(T))
		for i, n := 0, pmset.Len(); i < n; i++ {
			meth := pmset.At(i)
			if m := mset.Lookup(meth.Obj().Pkg(), meth.Obj().Name()); m != nil {
				meth = m
			}
			result = append(result, meth)
		}
	}
	return result
}

// offsetOf returns the (abstract) offset of field index within struct
// or tuple typ.
func (a *analysis) offsetOf(typ types.Type, index int) uint32 {
	var offset uint32
	switch t := typ.Underlying().(type) {
	case *types.Tuple:
		for i := 0; i < index; i++ {
			offset += a.sizeof(t.At(i).Type())
		}
	case *types.Struct:
		offset++ // the node for the struct itself
		for i := 0; i < index; i++ {
			offset += a.sizeof(t.Field(i).Type())
		}
	default:
		panic(fmt.Sprintf("offsetOf(%s : %T)", typ, typ))
	}
	return offset
}

// flatten returns a list of directly contained fields in the preorder
// traversal of the type tree of t.  The resulting elements are all
// scalars (basic types or pointerlike types), except for struct/array
// "identity" nodes, whose type is that of the aggregate.
//
// reflect.Value is considered pointerlike, similar to interface{}.
//
// Callers must not mutate the result.
//
func (a *analysis) flatten(t types.Type) []*fieldInfo {
	fl, ok := a.flattenMemo[t]
	if !ok {
		switch t := t.(type) {
		case *types.Named:
			u := t.Underlying()
			if isInterface(u) {
				// Debuggability hack: don't remove
				// the named type from interfaces as
				// they're very verbose.
				fl = append(fl, &fieldInfo{typ: t})
			} else {
				fl = a.flatten(u)
			}

		case *types.Basic,
			*types.Signature,
			*types.Chan,
			*types.Map,
			*types.Interface,
			*types.Slice,
			*types.Pointer:
			fl = append(fl, &fieldInfo{typ: t})

		case *types.Array:
			fl = append(fl, &fieldInfo{typ: t}) // identity node
			for _, fi := range a.flatten(t.Elem()) {
				fl = append(fl, &fieldInfo{typ: fi.typ, op: true, tail: fi})
			}

		case *types.Struct:
			fl = append(fl, &fieldInfo{typ: t}) // identity node
			for i, n := 0, t.NumFields(); i < n; i++ {
				f := t.Field(i)
				for _, fi := range a.flatten(f.Type()) {
					fl = append(fl, &fieldInfo{typ: fi.typ, op: f, tail: fi})
				}
			}

		case *types.Tuple:
			// No identity node: tuples are never address-taken.
			n := t.Len()
			if n == 1 {
				// Don't add a fieldInfo link for singletons,
				// e.g. in params/results.
				fl = append(fl, a.flatten(t.At(0).Type())...)
			} else {
				for i := 0; i < n; i++ {
					f := t.At(i)
					for _, fi := range a.flatten(f.Type()) {
						fl = append(fl, &fieldInfo{typ: fi.typ, op: i, tail: fi})
					}
				}
			}

		default:
			panic(t)
		}

		a.flattenMemo[t] = fl
	}

	return fl
}

// emitConv emits to f code to convert Value val to exactly type typ,
// and returns the converted value.  Implicit conversions are required
// by language assignability rules in assignments, parameter passing,
// etc.  Conversions cannot fail dynamically.
//
func emitConv(f *Function, val Value, typ types.Type) Value {
	t_src := val.Type()

	// Identical types?  Conversion is a no-op.
	if types.Identical(t_src, typ) {
		return val
	}

	ut_dst := typ.Underlying()
	ut_src := t_src.Underlying()

	// Just a change of type, but not value or representation?
	if isValuePreserving(ut_src, ut_dst) {
		c := &ChangeType{X: val}
		c.setType(typ)
		return f.emit(c)
	}

	// Conversion to, or construction of a value of, an interface type?
	if _, ok := ut_dst.(*types.Interface); ok {
		// Assignment from one interface type to another?
		if _, ok := ut_src.(*types.Interface); ok {
			c := &ChangeInterface{X: val}
			c.setType(typ)
			return f.emit(c)
		}

		// Untyped nil constant?  Return interface-typed nil constant.
		if ut_src == tUntypedNil {
			return nilConst(typ)
		}

		// Convert (non-nil) "untyped" literals to their default type.
		if t, ok := ut_src.(*types.Basic); ok && t.Info()&types.IsUntyped != 0 {
			val = emitConv(f, val, DefaultType(ut_src))
		}

		f.Pkg.Prog.needMethodsOf(val.Type())
		mi := &MakeInterface{X: val}
		mi.setType(typ)
		return f.emit(mi)
	}

	// Conversion of a compile-time constant value?
	if c, ok := val.(*Const); ok {
		if _, ok := ut_dst.(*types.Basic); ok || c.IsNil() {
			// Conversion of a compile-time constant to
			// another constant type results in a new
			// constant of the destination type and
			// (initially) the same abstract value.
			// We don't truncate the value yet.
			return NewConst(c.Value, typ)
		}

		// We're converting from constant to non-constant type,
		// e.g. string -> []byte/[]rune.
	}

	// A representation-changing conversion?
	// At least one of {ut_src,ut_dst} must be *Basic.
	// (The other may be []byte or []rune.)
	_, ok1 := ut_src.(*types.Basic)
	_, ok2 := ut_dst.(*types.Basic)
	if ok1 || ok2 {
		c := &Convert{X: val}
		c.setType(typ)
		return f.emit(c)
	}

	panic(fmt.Sprintf("in %s: cannot convert %s (%s) to %s", f, val, val.Type(), typ))
}

func reflectKind(t types.Type) reflect.Kind {
	switch t := t.(type) {
	case *types.Named:
		return reflectKind(t.Underlying())
	case *types.Basic:
		switch t.Kind() {
		case types.Bool:
			return reflect.Bool
		case types.Int:
			return reflect.Int
		case types.Int8:
			return reflect.Int8
		case types.Int16:
			return reflect.Int16
		case types.Int32:
			return reflect.Int32
		case types.Int64:
			return reflect.Int64
		case types.Uint:
			return reflect.Uint
		case types.Uint8:
			return reflect.Uint8
		case types.Uint16:
			return reflect.Uint16
		case types.Uint32:
			return reflect.Uint32
		case types.Uint64:
			return reflect.Uint64
		case types.Uintptr:
			return reflect.Uintptr
		case types.Float32:
			return reflect.Float32
		case types.Float64:
			return reflect.Float64
		case types.Complex64:
			return reflect.Complex64
		case types.Complex128:
			return reflect.Complex128
		case types.String:
			return reflect.String
		case types.UnsafePointer:
			return reflect.UnsafePointer
		}
	case *types.Array:
		return reflect.Array
	case *types.Chan:
		return reflect.Chan
	case *types.Signature:
		return reflect.Func
	case *types.Interface:
		return reflect.Interface
	case *types.Map:
		return reflect.Map
	case *types.Pointer:
		return reflect.Ptr
	case *types.Slice:
		return reflect.Slice
	case *types.Struct:
		return reflect.Struct
	}
	panic(fmt.Sprint("unexpected type: ", t))
}

// hashFor computes the hash of t.
func (h Hasher) hashFor(t types.Type) uint32 {
	// See Identical for rationale.
	switch t := t.(type) {
	case *types.Basic:
		return uint32(t.Kind())

	case *types.Array:
		return 9043 + 2*uint32(t.Len()) + 3*h.Hash(t.Elem())

	case *types.Slice:
		return 9049 + 2*h.Hash(t.Elem())

	case *types.Struct:
		var hash uint32 = 9059
		for i, n := 0, t.NumFields(); i < n; i++ {
			f := t.Field(i)
			if f.Anonymous() {
				hash += 8861
			}
			hash += hashString(t.Tag(i))
			hash += hashString(f.Name()) // (ignore f.Pkg)
			hash += h.Hash(f.Type())
		}
		return hash

	case *types.Pointer:
		return 9067 + 2*h.Hash(t.Elem())

	case *types.Signature:
		var hash uint32 = 9091
		if t.Variadic() {
			hash *= 8863
		}
		return hash + 3*h.hashTuple(t.Params()) + 5*h.hashTuple(t.Results())

	case *types.Interface:
		var hash uint32 = 9103
		for i, n := 0, t.NumMethods(); i < n; i++ {
			// See go/types.identicalMethods for rationale.
			// Method order is not significant.
			// Ignore m.Pkg().
			m := t.Method(i)
			hash += 3*hashString(m.Name()) + 5*h.Hash(m.Type())
		}
		return hash

	case *types.Map:
		return 9109 + 2*h.Hash(t.Key()) + 3*h.Hash(t.Elem())

	case *types.Chan:
		return 9127 + 2*uint32(t.Dir()) + 3*h.Hash(t.Elem())

	case *types.Named:
		// Not safe with a copying GC; objects may move.
		return uint32(reflect.ValueOf(t.Obj()).Pointer())

	case *types.Tuple:
		return h.hashTuple(t)
	}
	panic(t)
}