Golang Type.Field方法代码示例

func (tm *llvmTypeMap) Alignof(typ types.Type) int64 {
	switch typ := typ.Underlying().(type) {
	case *types.Array:
		return tm.Alignof(typ.Elem())
	case *types.Basic:
		switch typ.Kind() {
		case types.Int, types.Uint, types.Int64, types.Uint64,
			types.Float64, types.Complex64, types.Complex128:
			return int64(tm.target.TypeAllocSize(tm.inttype))
		case types.Uintptr, types.UnsafePointer, types.String:
			return int64(tm.target.PointerSize())
		}
		return tm.StdSizes.Alignof(typ)
	case *types.Struct:
		max := int64(1)
		for i := 0; i < typ.NumFields(); i++ {
			f := typ.Field(i)
			a := tm.Alignof(f.Type())
			if a > max {
				max = a
			}
		}
		return max
	}
	return int64(tm.target.PointerSize())
}

// 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 _, ok := u.(*types.Interface); ok {
				// 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.
			for i, n := 0, t.Len(); 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})
				}
			}

		case *types.Builtin:
			panic("flatten(*types.Builtin)") // not the type of any value

		default:
			panic(t)
		}

		a.flattenMemo[t] = fl
	}

	return fl
}

func (tm *LLVMTypeMap) Sizeof(typ types.Type) int64 {
	switch typ := typ.Underlying().(type) {
	case *types.Basic:
		switch typ.Kind() {
		case types.Int, types.Uint:
			return int64(tm.target.TypeAllocSize(tm.inttype))
		case types.Uintptr, types.UnsafePointer:
			return int64(tm.target.PointerSize())
		case types.String:
			return 2 * int64(tm.target.PointerSize())
		}
		return types.DefaultSizeof(typ)
	case *types.Array:
		eltsize := tm.Sizeof(typ.Elem())
		eltalign := tm.Alignof(typ.Elem())
		var eltpad int64
		if eltsize%eltalign != 0 {
			eltpad = eltalign - (eltsize % eltalign)
		}
		return (eltsize + eltpad) * typ.Len()
	case *types.Struct:
		if typ.NumFields() == 0 {
			return 0
		}
		fields := make([]*types.Field, int(typ.NumFields()))
		for i := range fields {
			fields[i] = typ.Field(i)
		}
		offsets := tm.Offsetsof(fields)
		n := len(fields)
		return offsets[n-1] + tm.Sizeof(fields[n-1].Type)
	}
	return int64(tm.target.PointerSize())
}

// hashFor computes the hash of t.
func (h Hasher) hashFor(t types.Type) uint32 {
	// See IsIdentical 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.IsVariadic() {
			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(uintptr(unsafe.Pointer(t.Obj())))
	}
	panic("unexpected type")
}

func (tm *llvmTypeMap) Sizeof(typ types.Type) int64 {
	switch typ := typ.Underlying().(type) {
	case *types.Basic:
		switch typ.Kind() {
		case types.Int, types.Uint:
			return int64(tm.target.TypeAllocSize(tm.inttype))
		case types.Uintptr, types.UnsafePointer:
			return int64(tm.target.PointerSize())
		}
		return tm.StdSizes.Sizeof(typ)
	case *types.Array:
		eltsize := tm.Sizeof(typ.Elem())
		eltalign := tm.Alignof(typ.Elem())
		var eltpad int64
		if eltsize%eltalign != 0 {
			eltpad = eltalign - (eltsize % eltalign)
		}
		return (eltsize + eltpad) * typ.Len()
	case *types.Slice:
		return 3 * int64(tm.target.PointerSize())
	case *types.Struct:
		n := typ.NumFields()
		if n == 0 {
			return 0
		}
		fields := make([]*types.Var, n)
		for i := range fields {
			fields[i] = typ.Field(i)
		}
		offsets := tm.Offsetsof(fields)
		return offsets[n-1] + tm.Sizeof(fields[n-1].Type())
	case *types.Interface:
		return int64((2 + typ.NumMethods()) * tm.target.PointerSize())
	}
	return int64(tm.target.PointerSize())
}

// 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))
}

// 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
}