Golang Type.Field方法代码示例

// 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
	}
}

// typeOKForCgoCall returns true if the type of arg is OK to pass to a
// C function using cgo. This is not true for Go types with embedded
// pointers.
func typeOKForCgoCall(t types.Type) bool {
	if t == nil {
		return true
	}
	switch t := t.Underlying().(type) {
	case *types.Chan, *types.Map, *types.Signature, *types.Slice:
		return false
	case *types.Pointer:
		return typeOKForCgoCall(t.Elem())
	case *types.Array:
		return typeOKForCgoCall(t.Elem())
	case *types.Struct:
		for i := 0; i < t.NumFields(); i++ {
			if !typeOKForCgoCall(t.Field(i).Type()) {
				return false
			}
		}
	}
	return true
}

// load returns the value of type T in *addr.
func load(T types.Type, addr *value) value {
	switch T := T.Underlying().(type) {
	case *types.Struct:
		v := (*addr).(structure)
		a := make(structure, len(v))
		for i := range a {
			a[i] = load(T.Field(i).Type(), &v[i])
		}
		return a
	case *types.Array:
		v := (*addr).(array)
		a := make(array, len(v))
		for i := range a {
			a[i] = load(T.Elem(), &v[i])
		}
		return a
	default:
		return *addr
	}
}

//.........这里部分代码省略.........
		y := y.(*types.Array)
		if x.Len() != y.Len() {
			return fmt.Errorf("unequal array lengths: %d vs %d", x.Len(), y.Len())
		}
		if err := equalType(x.Elem(), y.Elem()); err != nil {
			return fmt.Errorf("array elements: %s", err)
		}
	case *types.Basic:
		y := y.(*types.Basic)
		if x.Kind() != y.Kind() {
			return fmt.Errorf("unequal basic types: %s vs %s", x, y)
		}
	case *types.Chan:
		y := y.(*types.Chan)
		if x.Dir() != y.Dir() {
			return fmt.Errorf("unequal channel directions: %d vs %d", x.Dir(), y.Dir())
		}
		if err := equalType(x.Elem(), y.Elem()); err != nil {
			return fmt.Errorf("channel elements: %s", err)
		}
	case *types.Map:
		y := y.(*types.Map)
		if err := equalType(x.Key(), y.Key()); err != nil {
			return fmt.Errorf("map keys: %s", err)
		}
		if err := equalType(x.Elem(), y.Elem()); err != nil {
			return fmt.Errorf("map values: %s", err)
		}
	case *types.Named:
		y := y.(*types.Named)
		if x.String() != y.String() {
			return fmt.Errorf("unequal named types: %s vs %s", x, y)
		}
	case *types.Pointer:
		y := y.(*types.Pointer)
		if err := equalType(x.Elem(), y.Elem()); err != nil {
			return fmt.Errorf("pointer elements: %s", err)
		}
	case *types.Signature:
		y := y.(*types.Signature)
		if err := equalType(x.Params(), y.Params()); err != nil {
			return fmt.Errorf("parameters: %s", err)
		}
		if err := equalType(x.Results(), y.Results()); err != nil {
			return fmt.Errorf("results: %s", err)
		}
		if x.Variadic() != y.Variadic() {
			return fmt.Errorf("unequal varidicity: %t vs %t",
				x.Variadic(), y.Variadic())
		}
		if (x.Recv() != nil) != (y.Recv() != nil) {
			return fmt.Errorf("unequal receivers: %s vs %s", x.Recv(), y.Recv())
		}
		if x.Recv() != nil {
			// TODO(adonovan): fix: this assertion fires for interface methods.
			// The type of the receiver of an interface method is a named type
			// if the Package was loaded from export data, or an unnamed (interface)
			// type if the Package was produced by type-checking ASTs.
			// if err := equalType(x.Recv().Type(), y.Recv().Type()); err != nil {
			// 	return fmt.Errorf("receiver: %s", err)
			// }
		}
	case *types.Slice:
		y := y.(*types.Slice)
		if err := equalType(x.Elem(), y.Elem()); err != nil {
			return fmt.Errorf("slice elements: %s", err)
		}
	case *types.Struct:
		y := y.(*types.Struct)
		if x.NumFields() != y.NumFields() {
			return fmt.Errorf("unequal struct fields: %d vs %d",
				x.NumFields(), y.NumFields())
		}
		for i := 0; i < x.NumFields(); i++ {
			xf := x.Field(i)
			yf := y.Field(i)
			if xf.Name() != yf.Name() {
				return fmt.Errorf("mismatched fields: %s vs %s", xf, yf)
			}
			if err := equalType(xf.Type(), yf.Type()); err != nil {
				return fmt.Errorf("struct field %s: %s", xf.Name(), err)
			}
			if x.Tag(i) != y.Tag(i) {
				return fmt.Errorf("struct field %s has unequal tags: %q vs %q",
					xf.Name(), x.Tag(i), y.Tag(i))
			}
		}
	case *types.Tuple:
		y := y.(*types.Tuple)
		if x.Len() != y.Len() {
			return fmt.Errorf("unequal tuple lengths: %d vs %d", x.Len(), y.Len())
		}
		for i := 0; i < x.Len(); i++ {
			if err := equalType(x.At(i).Type(), y.At(i).Type()); err != nil {
				return fmt.Errorf("tuple element %d: %s", i, err)
			}
		}
	}
	return nil
}

// 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
}

// zero returns a new "zero" value of the specified type.
func zero(t types.Type) value {
	switch t := t.(type) {
	case *types.Basic:
		if t.Kind() == types.UntypedNil {
			panic("untyped nil has no zero value")
		}
		if t.Info()&types.IsUntyped != 0 {
			// TODO(adonovan): make it an invariant that
			// this is unreachable.  Currently some
			// constants have 'untyped' types when they
			// should be defaulted by the typechecker.
			t = ssa.DefaultType(t).(*types.Basic)
		}
		switch t.Kind() {
		case types.Bool:
			return false
		case types.Int:
			return int(0)
		case types.Int8:
			return int8(0)
		case types.Int16:
			return int16(0)
		case types.Int32:
			return int32(0)
		case types.Int64:
			return int64(0)
		case types.Uint:
			return uint(0)
		case types.Uint8:
			return uint8(0)
		case types.Uint16:
			return uint16(0)
		case types.Uint32:
			return uint32(0)
		case types.Uint64:
			return uint64(0)
		case types.Uintptr:
			return uintptr(0)
		case types.Float32:
			return float32(0)
		case types.Float64:
			return float64(0)
		case types.Complex64:
			return complex64(0)
		case types.Complex128:
			return complex128(0)
		case types.String:
			return ""
		case types.UnsafePointer:
			return unsafe.Pointer(nil)
		default:
			panic(fmt.Sprint("zero for unexpected type:", t))
		}
	case *types.Pointer:
		return (*value)(nil)
	case *types.Array:
		a := make(array, t.Len())
		for i := range a {
			a[i] = zero(t.Elem())
		}
		return a
	case *types.Named:
		return zero(t.Underlying())
	case *types.Interface:
		return iface{} // nil type, methodset and value
	case *types.Slice:
		return []value(nil)
	case *types.Struct:
		s := make(structure, t.NumFields())
		for i := range s {
			s[i] = zero(t.Field(i).Type())
		}
		return s
	case *types.Tuple:
		if t.Len() == 1 {
			return zero(t.At(0).Type())
		}
		s := make(tuple, t.Len())
		for i := range s {
			s[i] = zero(t.At(i).Type())
		}
		return s
	case *types.Chan:
		return chan value(nil)
	case *types.Map:
		if usesBuiltinMap(t.Key()) {
			return map[value]value(nil)
		}
		return (*hashmap)(nil)
	case *types.Signature:
		return (*ssa.Function)(nil)
	}
	panic(fmt.Sprint("zero: unexpected ", 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)
}