reflect/protoreflect/value_union.go - protobuf - Git at Google

 // Copyright 2018 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 package protoreflect

 import (
 	"fmt"
 	"math"
 	"reflect"
 )

 // Value is a union where only one Go type may be set at a time.
 // The Value is used to represent all possible values a field may take.
 // The following shows what Go type is used to represent each proto Kind:
 //
 //	+------------+-------------------------------------+
 //	| Go type    | Protobuf kind                       |
 //	+------------+-------------------------------------+
 //	| bool       | BoolKind                            |
 //	| int32      | Int32Kind, Sint32Kind, Sfixed32Kind |
 //	| int64      | Int64Kind, Sint64Kind, Sfixed64Kind |
 //	| uint32     | Uint32Kind, Fixed32Kind             |
 //	| uint64     | Uint64Kind, Fixed64Kind             |
 //	| float32    | FloatKind                           |
 //	| float64    | DoubleKind                          |
 //	| string     | StringKind                          |
 //	| []byte     | BytesKind                           |
 //	| EnumNumber | EnumKind                            |
 //	+------------+-------------------------------------+
 //	| Message    | MessageKind, GroupKind              |
 //	| List       |                                     |
 //	| Map        |                                     |
 //	+------------+-------------------------------------+
 //
 // Multiple protobuf Kinds may be represented by a single Go type if the type
 // can losslessly represent the information for the proto kind. For example,
 // Int64Kind, Sint64Kind, and Sfixed64Kind are all represented by int64,
 // but use different integer encoding methods.
 //
 // The List or Map types are used if the FieldDescriptor.Cardinality of the
 // corresponding field is Repeated and a Map if and only if
 // FieldDescriptor.IsMap is true.
 //
 // Converting to/from a Value and a concrete Go value panics on type mismatch.
 // For example, ValueOf("hello").Int() panics because this attempts to
 // retrieve an int64 from a string.
 type Value value

 // The protoreflect API uses a custom Value union type instead of interface{}
 // to keep the future open for performance optimizations. Using an interface{}
 // always incurs an allocation for primitives (e.g., int64) since it needs to
 // be boxed on the heap (as interfaces can only contain pointers natively).
 // Instead, we represent the Value union as a flat struct that internally keeps
 // track of which type is set. Using unsafe, the Value union can be reduced
 // down to 24B, which is identical in size to a slice.
 //
 // The latest compiler (Go1.11) currently suffers from some limitations:
 //	• With inlining, the compiler should be able to statically prove that
 //	only one of these switch cases are taken and inline one specific case.
 //	See https://golang.org/issue/22310.

 // ValueOf returns a Value initialized with the concrete value stored in v.
 // This panics if the type does not match one of the allowed types in the
 // Value union.
 //
 // After calling ValueOf on a []byte, the slice must no longer be mutated.
 func ValueOf(v interface{}) Value {
 	switch v := v.(type) {
 	case nil:
 		return Value{}
 	case bool:
 		if v {
 			return Value{typ: boolType, num: 1}
 		} else {
 			return Value{typ: boolType, num: 0}
 		}
 	case int32:
 		return Value{typ: int32Type, num: uint64(v)}
 	case int64:
 		return Value{typ: int64Type, num: uint64(v)}
 	case uint32:
 		return Value{typ: uint32Type, num: uint64(v)}
 	case uint64:
 		return Value{typ: uint64Type, num: uint64(v)}
 	case float32:
 		return Value{typ: float32Type, num: uint64(math.Float64bits(float64(v)))}
 	case float64:
 		return Value{typ: float64Type, num: uint64(math.Float64bits(float64(v)))}
 	case string:
 		return valueOfString(v)
 	case []byte:
 		return valueOfBytes(v[:len(v):len(v)])
 	case EnumNumber:
 		return Value{typ: enumType, num: uint64(v)}
 	case Message, List, Map:
 		return valueOfIface(v)
 	default:
 		// TODO: Special case Enum, ProtoMessage, *[]T, and *map[K]V?
 		// Note: this would violate the documented invariant in Interface.
 		panic(fmt.Sprintf("invalid type: %v", reflect.TypeOf(v)))
 	}
 }

 // IsValid reports whether v is populated with a value.
 func (v Value) IsValid() bool {
 	return v.typ != nilType
 }

 // Interface returns v as an interface{}.
 // Returned []byte values must not be mutated.
 //
 // Invariant: v == ValueOf(v).Interface()
 func (v Value) Interface() interface{} {
 	switch v.typ {
 	case nilType:
 		return nil
 	case boolType:
 		return v.Bool()
 	case int32Type:
 		return int32(v.Int())
 	case int64Type:
 		return int64(v.Int())
 	case uint32Type:
 		return uint32(v.Uint())
 	case uint64Type:
 		return uint64(v.Uint())
 	case float32Type:
 		return float32(v.Float())
 	case float64Type:
 		return float64(v.Float())
 	case stringType:
 		return v.String()
 	case bytesType:
 		return v.Bytes()
 	case enumType:
 		return v.Enum()
 	default:
 		return v.getIface()
 	}
 }

 // Bool returns v as a bool and panics if the type is not a bool.
 func (v Value) Bool() bool {
 	switch v.typ {
 	case boolType:
 		return v.num > 0
 	default:
 		panic("proto: value type mismatch")
 	}
 }

 // Int returns v as a int64 and panics if the type is not a int32 or int64.
 func (v Value) Int() int64 {
 	switch v.typ {
 	case int32Type, int64Type:
 		return int64(v.num)
 	default:
 		panic("proto: value type mismatch")
 	}
 }

 // Uint returns v as a uint64 and panics if the type is not a uint32 or uint64.
 func (v Value) Uint() uint64 {
 	switch v.typ {
 	case uint32Type, uint64Type:
 		return uint64(v.num)
 	default:
 		panic("proto: value type mismatch")
 	}
 }

 // Float returns v as a float64 and panics if the type is not a float32 or float64.
 func (v Value) Float() float64 {
 	switch v.typ {
 	case float32Type, float64Type:
 		return math.Float64frombits(uint64(v.num))
 	default:
 		panic("proto: value type mismatch")
 	}
 }

 // String returns v as a string. Since this method implements fmt.Stringer,
 // this returns the formatted string value for any non-string type.
 func (v Value) String() string {
 	switch v.typ {
 	case stringType:
 		return v.getString()
 	default:
 		return fmt.Sprint(v.Interface())
 	}
 }

 // Bytes returns v as a []byte and panics if the type is not a []byte.
 // The returned slice must not be mutated.
 func (v Value) Bytes() []byte {
 	switch v.typ {
 	case bytesType:
 		return v.getBytes()
 	default:
 		panic("proto: value type mismatch")
 	}
 }

 // Enum returns v as a EnumNumber and panics if the type is not a EnumNumber.
 func (v Value) Enum() EnumNumber {
 	switch v.typ {
 	case enumType:
 		return EnumNumber(v.num)
 	default:
 		panic("proto: value type mismatch")
 	}
 }

 // Message returns v as a Message and panics if the type is not a Message.
 func (v Value) Message() Message {
 	switch v := v.getIface().(type) {
 	case Message:
 		return v
 	default:
 		panic("proto: value type mismatch")
 	}
 }

 // List returns v as a List and panics if the type is not a List.
 func (v Value) List() List {
 	switch v := v.getIface().(type) {
 	case List:
 		return v
 	default:
 		panic("proto: value type mismatch")
 	}
 }

 // Map returns v as a Map and panics if the type is not a Map.
 func (v Value) Map() Map {
 	switch v := v.getIface().(type) {
 	case Map:
 		return v
 	default:
 		panic("proto: value type mismatch")
 	}
 }

 // MapKey returns v as a MapKey and panics for invalid MapKey types.
 func (v Value) MapKey() MapKey {
 	switch v.typ {
 	case boolType, int32Type, int64Type, uint32Type, uint64Type, stringType:
 		return MapKey(v)
 	}
 	panic("proto: invalid map key type")
 }

 // MapKey is used to index maps, where the Go type of the MapKey must match
 // the specified key Kind (see MessageDescriptor.IsMapEntry).
 // The following shows what Go type is used to represent each proto Kind:
 //
 //	+---------+-------------------------------------+
 //	| Go type | Protobuf kind                       |
 //	+---------+-------------------------------------+
 //	| bool    | BoolKind                            |
 //	| int32   | Int32Kind, Sint32Kind, Sfixed32Kind |
 //	| int64   | Int64Kind, Sint64Kind, Sfixed64Kind |
 //	| uint32  | Uint32Kind, Fixed32Kind             |
 //	| uint64  | Uint64Kind, Fixed64Kind             |
 //	| string  | StringKind                          |
 //	+---------+-------------------------------------+
 //
 // A MapKey is constructed and accessed through a Value:
 //	k := ValueOf("hash").MapKey() // convert string to MapKey
 //	s := k.String()               // convert MapKey to string
 //
 // The MapKey is a strict subset of valid types used in Value;
 // converting a Value to a MapKey with an invalid type panics.
 type MapKey value

 // IsValid reports whether k is populated with a value.
 func (k MapKey) IsValid() bool {
 	return Value(k).IsValid()
 }

 // Interface returns k as an interface{}.
 func (k MapKey) Interface() interface{} {
 	return Value(k).Interface()
 }

 // Bool returns k as a bool and panics if the type is not a bool.
 func (k MapKey) Bool() bool {
 	return Value(k).Bool()
 }

 // Int returns k as a int64 and panics if the type is not a int32 or int64.
 func (k MapKey) Int() int64 {
 	return Value(k).Int()
 }

 // Uint returns k as a uint64 and panics if the type is not a uint32 or uint64.
 func (k MapKey) Uint() uint64 {
 	return Value(k).Uint()
 }

 // String returns k as a string. Since this method implements fmt.Stringer,
 // this returns the formatted string value for any non-string type.
 func (k MapKey) String() string {
 	return Value(k).String()
 }

 // Value returns k as a Value.
 func (k MapKey) Value() Value {
 	return Value(k)
 }
	// Copyright 2018 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	package protoreflect

	import (
	"fmt"
	"math"
	"reflect"
	)

	// Value is a union where only one Go type may be set at a time.
	// The Value is used to represent all possible values a field may take.
	// The following shows what Go type is used to represent each proto Kind:
	//
	// +------------+-------------------------------------+
	// \| Go type \| Protobuf kind \|
	// +------------+-------------------------------------+
	// \| bool \| BoolKind \|
	// \| int32 \| Int32Kind, Sint32Kind, Sfixed32Kind \|
	// \| int64 \| Int64Kind, Sint64Kind, Sfixed64Kind \|
	// \| uint32 \| Uint32Kind, Fixed32Kind \|
	// \| uint64 \| Uint64Kind, Fixed64Kind \|
	// \| float32 \| FloatKind \|
	// \| float64 \| DoubleKind \|
	// \| string \| StringKind \|
	// \| []byte \| BytesKind \|
	// \| EnumNumber \| EnumKind \|
	// +------------+-------------------------------------+
	// \| Message \| MessageKind, GroupKind \|
	// \| List \| \|
	// \| Map \| \|
	// +------------+-------------------------------------+
	//
	// Multiple protobuf Kinds may be represented by a single Go type if the type
	// can losslessly represent the information for the proto kind. For example,
	// Int64Kind, Sint64Kind, and Sfixed64Kind are all represented by int64,
	// but use different integer encoding methods.
	//
	// The List or Map types are used if the FieldDescriptor.Cardinality of the
	// corresponding field is Repeated and a Map if and only if
	// FieldDescriptor.IsMap is true.
	//
	// Converting to/from a Value and a concrete Go value panics on type mismatch.
	// For example, ValueOf("hello").Int() panics because this attempts to
	// retrieve an int64 from a string.
	type Value value

	// The protoreflect API uses a custom Value union type instead of interface{}
	// to keep the future open for performance optimizations. Using an interface{}
	// always incurs an allocation for primitives (e.g., int64) since it needs to
	// be boxed on the heap (as interfaces can only contain pointers natively).
	// Instead, we represent the Value union as a flat struct that internally keeps
	// track of which type is set. Using unsafe, the Value union can be reduced
	// down to 24B, which is identical in size to a slice.
	//
	// The latest compiler (Go1.11) currently suffers from some limitations:
	// • With inlining, the compiler should be able to statically prove that
	// only one of these switch cases are taken and inline one specific case.
	// See https://golang.org/issue/22310.

	// ValueOf returns a Value initialized with the concrete value stored in v.
	// This panics if the type does not match one of the allowed types in the
	// Value union.
	//
	// After calling ValueOf on a []byte, the slice must no longer be mutated.
	func ValueOf(v interface{}) Value {
	switch v := v.(type) {
	case nil:
	return Value{}
	case bool:
	if v {
	return Value{typ: boolType, num: 1}
	} else {
	return Value{typ: boolType, num: 0}
	}
	case int32:
	return Value{typ: int32Type, num: uint64(v)}
	case int64:
	return Value{typ: int64Type, num: uint64(v)}
	case uint32:
	return Value{typ: uint32Type, num: uint64(v)}
	case uint64:
	return Value{typ: uint64Type, num: uint64(v)}
	case float32:
	return Value{typ: float32Type, num: uint64(math.Float64bits(float64(v)))}
	case float64:
	return Value{typ: float64Type, num: uint64(math.Float64bits(float64(v)))}
	case string:
	return valueOfString(v)
	case []byte:
	return valueOfBytes(v[:len(v):len(v)])
	case EnumNumber:
	return Value{typ: enumType, num: uint64(v)}
	case Message, List, Map:
	return valueOfIface(v)
	default:
	// TODO: Special case Enum, ProtoMessage, []T, and map[K]V?
	// Note: this would violate the documented invariant in Interface.
	panic(fmt.Sprintf("invalid type: %v", reflect.TypeOf(v)))
	}
	}

	// IsValid reports whether v is populated with a value.
	func (v Value) IsValid() bool {
	return v.typ != nilType
	}

	// Interface returns v as an interface{}.
	// Returned []byte values must not be mutated.
	//
	// Invariant: v == ValueOf(v).Interface()
	func (v Value) Interface() interface{} {
	switch v.typ {
	case nilType:
	return nil
	case boolType:
	return v.Bool()
	case int32Type:
	return int32(v.Int())
	case int64Type:
	return int64(v.Int())
	case uint32Type:
	return uint32(v.Uint())
	case uint64Type:
	return uint64(v.Uint())
	case float32Type:
	return float32(v.Float())
	case float64Type:
	return float64(v.Float())
	case stringType:
	return v.String()
	case bytesType:
	return v.Bytes()
	case enumType:
	return v.Enum()
	default:
	return v.getIface()
	}
	}

	// Bool returns v as a bool and panics if the type is not a bool.
	func (v Value) Bool() bool {
	switch v.typ {
	case boolType:
	return v.num > 0
	default:
	panic("proto: value type mismatch")
	}
	}

	// Int returns v as a int64 and panics if the type is not a int32 or int64.
	func (v Value) Int() int64 {
	switch v.typ {
	case int32Type, int64Type:
	return int64(v.num)
	default:
	panic("proto: value type mismatch")
	}
	}

	// Uint returns v as a uint64 and panics if the type is not a uint32 or uint64.
	func (v Value) Uint() uint64 {
	switch v.typ {
	case uint32Type, uint64Type:
	return uint64(v.num)
	default:
	panic("proto: value type mismatch")
	}
	}

	// Float returns v as a float64 and panics if the type is not a float32 or float64.
	func (v Value) Float() float64 {
	switch v.typ {
	case float32Type, float64Type:
	return math.Float64frombits(uint64(v.num))
	default:
	panic("proto: value type mismatch")
	}
	}

	// String returns v as a string. Since this method implements fmt.Stringer,
	// this returns the formatted string value for any non-string type.
	func (v Value) String() string {
	switch v.typ {
	case stringType:
	return v.getString()
	default:
	return fmt.Sprint(v.Interface())
	}
	}

	// Bytes returns v as a []byte and panics if the type is not a []byte.
	// The returned slice must not be mutated.
	func (v Value) Bytes() []byte {
	switch v.typ {
	case bytesType:
	return v.getBytes()
	default:
	panic("proto: value type mismatch")
	}
	}

	// Enum returns v as a EnumNumber and panics if the type is not a EnumNumber.
	func (v Value) Enum() EnumNumber {
	switch v.typ {
	case enumType:
	return EnumNumber(v.num)
	default:
	panic("proto: value type mismatch")
	}
	}

	// Message returns v as a Message and panics if the type is not a Message.
	func (v Value) Message() Message {
	switch v := v.getIface().(type) {
	case Message:
	return v
	default:
	panic("proto: value type mismatch")
	}
	}

	// List returns v as a List and panics if the type is not a List.
	func (v Value) List() List {
	switch v := v.getIface().(type) {
	case List:
	return v
	default:
	panic("proto: value type mismatch")
	}
	}

	// Map returns v as a Map and panics if the type is not a Map.
	func (v Value) Map() Map {
	switch v := v.getIface().(type) {
	case Map:
	return v
	default:
	panic("proto: value type mismatch")
	}
	}

	// MapKey returns v as a MapKey and panics for invalid MapKey types.
	func (v Value) MapKey() MapKey {
	switch v.typ {
	case boolType, int32Type, int64Type, uint32Type, uint64Type, stringType:
	return MapKey(v)
	}
	panic("proto: invalid map key type")
	}

	// MapKey is used to index maps, where the Go type of the MapKey must match
	// the specified key Kind (see MessageDescriptor.IsMapEntry).
	// The following shows what Go type is used to represent each proto Kind:
	//
	// +---------+-------------------------------------+
	// \| Go type \| Protobuf kind \|
	// +---------+-------------------------------------+
	// \| bool \| BoolKind \|
	// \| int32 \| Int32Kind, Sint32Kind, Sfixed32Kind \|
	// \| int64 \| Int64Kind, Sint64Kind, Sfixed64Kind \|
	// \| uint32 \| Uint32Kind, Fixed32Kind \|
	// \| uint64 \| Uint64Kind, Fixed64Kind \|
	// \| string \| StringKind \|
	// +---------+-------------------------------------+
	//
	// A MapKey is constructed and accessed through a Value:
	// k := ValueOf("hash").MapKey() // convert string to MapKey
	// s := k.String() // convert MapKey to string
	//
	// The MapKey is a strict subset of valid types used in Value;
	// converting a Value to a MapKey with an invalid type panics.
	type MapKey value

	// IsValid reports whether k is populated with a value.
	func (k MapKey) IsValid() bool {
	return Value(k).IsValid()
	}

	// Interface returns k as an interface{}.
	func (k MapKey) Interface() interface{} {
	return Value(k).Interface()
	}

	// Bool returns k as a bool and panics if the type is not a bool.
	func (k MapKey) Bool() bool {
	return Value(k).Bool()
	}

	// Int returns k as a int64 and panics if the type is not a int32 or int64.
	func (k MapKey) Int() int64 {
	return Value(k).Int()
	}

	// Uint returns k as a uint64 and panics if the type is not a uint32 or uint64.
	func (k MapKey) Uint() uint64 {
	return Value(k).Uint()
	}

	// String returns k as a string. Since this method implements fmt.Stringer,
	// this returns the formatted string value for any non-string type.
	func (k MapKey) String() string {
	return Value(k).String()
	}

	// Value returns k as a Value.
	func (k MapKey) Value() Value {
	return Value(k)
	}