Golang Type.Key方法代码示例

// 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))
}

// matchArgTypeInternal is the internal version of matchArgType. It carries a map
// remembering what types are in progress so we don't recur when faced with recursive
// types or mutually recursive types.
func (f *File) matchArgTypeInternal(t printfArgType, typ types.Type, arg ast.Expr, inProgress map[types.Type]bool) bool {
	// %v, %T accept any argument type.
	if t == anyType {
		return true
	}
	if typ == nil {
		// external call
		typ = f.pkg.types[arg].Type
		if typ == nil {
			return true // probably a type check problem
		}
	}
	// If the type implements fmt.Formatter, we have nothing to check.
	// But (see issue 6259) that's not easy to verify, so instead we see
	// if its method set contains a Format function. We could do better,
	// even now, but we don't need to be 100% accurate. Wait for 6259 to
	// be fixed instead. TODO.
	if f.hasMethod(typ, "Format") {
		return true
	}
	// If we can use a string, might arg (dynamically) implement the Stringer or Error interface?
	if t&argString != 0 {
		if types.AssertableTo(errorType, typ) || types.AssertableTo(stringerType, typ) {
			return true
		}
	}

	typ = typ.Underlying()
	if inProgress[typ] {
		// We're already looking at this type. The call that started it will take care of it.
		return true
	}
	inProgress[typ] = true

	switch typ := typ.(type) {
	case *types.Signature:
		return t&argPointer != 0

	case *types.Map:
		// Recur: map[int]int matches %d.
		return t&argPointer != 0 ||
			(f.matchArgTypeInternal(t, typ.Key(), arg, inProgress) && f.matchArgTypeInternal(t, typ.Elem(), arg, inProgress))

	case *types.Chan:
		return t&argPointer != 0

	case *types.Array:
		// Same as slice.
		if types.Identical(typ.Elem().Underlying(), types.Typ[types.Byte]) && t&argString != 0 {
			return true // %s matches []byte
		}
		// Recur: []int matches %d.
		return t&argPointer != 0 || f.matchArgTypeInternal(t, typ.Elem().Underlying(), arg, inProgress)

	case *types.Slice:
		// Same as array.
		if types.Identical(typ.Elem().Underlying(), types.Typ[types.Byte]) && t&argString != 0 {
			return true // %s matches []byte
		}
		// Recur: []int matches %d. But watch out for
		//	type T []T
		// If the element is a pointer type (type T[]*T), it's handled fine by the Pointer case below.
		return t&argPointer != 0 || f.matchArgTypeInternal(t, typ.Elem(), arg, inProgress)

	case *types.Pointer:
		// Ugly, but dealing with an edge case: a known pointer to an invalid type,
		// probably something from a failed import.
		if typ.Elem().String() == "invalid type" {
			if *verbose {
				f.Warnf(arg.Pos(), "printf argument %v is pointer to invalid or unknown type", f.gofmt(arg))
			}
			return true // special case
		}
		// If it's actually a pointer with %p, it prints as one.
		if t == argPointer {
			return true
		}
		// If it's pointer to struct, that's equivalent in our analysis to whether we can print the struct.
		if str, ok := typ.Elem().Underlying().(*types.Struct); ok {
			return f.matchStructArgType(t, str, arg, inProgress)
		}
		// The rest can print with %p as pointers, or as integers with %x etc.
		return t&(argInt|argPointer) != 0

	case *types.Struct:
		return f.matchStructArgType(t, typ, arg, inProgress)

	case *types.Interface:
		// If the static type of the argument is empty interface, there's little we can do.
		// Example:
		//	func f(x interface{}) { fmt.Printf("%s", x) }
		// Whether x is valid for %s depends on the type of the argument to f. One day
		// we will be able to do better. For now, we assume that empty interface is OK
		// but non-empty interfaces, with Stringer and Error handled above, are errors.
		return typ.NumMethods() == 0

	case *types.Basic:
//.........这里部分代码省略.........

// 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)
}