internal/encoding/pack: initial commit

Package pack enables manual encoding and decoding of protobuf wire data.
This package is intended only for testing and debugging purposes.
Message.Marshal is useful for hand-crafting raw wire testdata in tests
in a readable form.
Message.Unmarshal is useful for parsing raw wire data for debugging.
For that reason, effort was put into trying to get its string formatted
output look humanly readable.

High-level API:
	type Number = wire.Number
		const MinValidNumber Number = wire.MinValidNumber ...
	type Type = wire.Type
		const VarintType Type = wire.VarintType ...

	type Token token
	type Tag struct { ... }
	type Bool bool
	type Varint int64
	type Svarint int64
	type Uvarint uint64
	type Int32 int32
	type Uint32 uint32
	type Float32 float32
	type Int64 int64
	type Uint64 uint64
	type Float64 float64
	type String string
	type Bytes []byte
	type LengthPrefix Message
	type Denormalized struct { ... }
	type Raw []byte

	type Message []Token
		func (Message) Size() int
		func (Message) Marshal() []byte
		func (*Message) Unmarshal(in []byte)
		func (*Message) UnmarshalDescriptor(in []byte, desc protoreflect.MessageDescriptor)
		func (Message) Format(s fmt.State, r rune)

Change-Id: Id99b340971a09c8a040838b155782a5d32b548bc
Reviewed-on: https://go-review.googlesource.com/129404
Reviewed-by: Herbie Ong <herbie@google.com>
diff --git a/internal/encoding/pack/pack_test.go b/internal/encoding/pack/pack_test.go
new file mode 100644
index 0000000..36a6300
--- /dev/null
+++ b/internal/encoding/pack/pack_test.go
@@ -0,0 +1,352 @@
+// 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 pack
+
+import (
+	"bytes"
+	"encoding/hex"
+	"fmt"
+	"math"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	pref "google.golang.org/proto/reflect/protoreflect"
+	ptype "google.golang.org/proto/reflect/prototype"
+)
+
+var msgDesc = func() pref.MessageDescriptor {
+	mtyp, err := ptype.NewMessage(&ptype.StandaloneMessage{
+		Syntax:   pref.Proto2,
+		FullName: "Message",
+		Fields: []ptype.Field{
+			{Name: "F1", Number: 1, Cardinality: pref.Repeated, Kind: pref.BoolKind, IsPacked: true},
+			{Name: "F2", Number: 2, Cardinality: pref.Repeated, Kind: pref.Int64Kind, IsPacked: true},
+			{Name: "F3", Number: 3, Cardinality: pref.Repeated, Kind: pref.Sint64Kind, IsPacked: true},
+			{Name: "F4", Number: 4, Cardinality: pref.Repeated, Kind: pref.Uint64Kind, IsPacked: true},
+			{Name: "F5", Number: 5, Cardinality: pref.Repeated, Kind: pref.Fixed32Kind, IsPacked: true},
+			{Name: "F6", Number: 6, Cardinality: pref.Repeated, Kind: pref.Sfixed32Kind, IsPacked: true},
+			{Name: "F7", Number: 7, Cardinality: pref.Repeated, Kind: pref.FloatKind, IsPacked: true},
+			{Name: "F8", Number: 8, Cardinality: pref.Repeated, Kind: pref.Fixed64Kind, IsPacked: true},
+			{Name: "F9", Number: 9, Cardinality: pref.Repeated, Kind: pref.Sfixed64Kind, IsPacked: true},
+			{Name: "F10", Number: 10, Cardinality: pref.Repeated, Kind: pref.DoubleKind, IsPacked: true},
+			{Name: "F11", Number: 11, Cardinality: pref.Optional, Kind: pref.StringKind},
+			{Name: "F12", Number: 12, Cardinality: pref.Optional, Kind: pref.BytesKind},
+			{Name: "F13", Number: 13, Cardinality: pref.Optional, Kind: pref.MessageKind, MessageType: ptype.PlaceholderMessage("Message")},
+			{Name: "F14", Number: 14, Cardinality: pref.Optional, Kind: pref.GroupKind, MessageType: ptype.PlaceholderMessage("Message")}},
+	})
+	if err != nil {
+		panic(err)
+	}
+	return mtyp
+}()
+
+// dhex decodes a hex-string and returns the bytes and panics if s is invalid.
+func dhex(s string) []byte {
+	b, err := hex.DecodeString(s)
+	if err != nil {
+		panic(err)
+	}
+	return b
+}
+
+func TestPack(t *testing.T) {
+	tests := []struct {
+		raw []byte
+		msg Message
+
+		wantOutCompact string
+		wantOutMulti   string
+		wantOutSource  string
+	}{{
+		raw: dhex("080088808080800002088280808080000a09010002828080808000"),
+		msg: Message{
+			Tag{1, VarintType}, Bool(false),
+			Denormalized{5, Tag{1, VarintType}}, Uvarint(2),
+			Tag{1, VarintType}, Denormalized{5, Uvarint(2)},
+			Tag{1, BytesType}, LengthPrefix{Bool(true), Bool(false), Uvarint(2), Denormalized{5, Uvarint(2)}},
+		},
+		wantOutSource: `pack.Message{
+	pack.Tag{1, pack.VarintType}, pack.Bool(false),
+	pack.Denormalized{+5, pack.Tag{1, pack.VarintType}}, pack.Uvarint(2),
+	pack.Tag{1, pack.VarintType}, pack.Denormalized{+5, pack.Uvarint(2)},
+	pack.Tag{1, pack.BytesType}, pack.LengthPrefix{pack.Bool(true), pack.Bool(false), pack.Uvarint(2), pack.Denormalized{+5, pack.Uvarint(2)}},
+}`,
+	}, {
+		raw: dhex("100010828080808000121980808080808080808001ffffffffffffffff7f828080808000"),
+		msg: Message{
+			Tag{2, VarintType}, Varint(0),
+			Tag{2, VarintType}, Denormalized{5, Varint(2)},
+			Tag{2, BytesType}, LengthPrefix{Varint(math.MinInt64), Varint(math.MaxInt64), Denormalized{5, Varint(2)}},
+		},
+		wantOutCompact: `Message{Tag{2, Varint}, Varint(0), Tag{2, Varint}, Denormalized{+5, Varint(2)}, Tag{2, Bytes}, LengthPrefix{Varint(-9223372036854775808), Varint(9223372036854775807), Denormalized{+5, Varint(2)}}}`,
+	}, {
+		raw: dhex("1801188180808080001a1affffffffffffffffff01feffffffffffffffff01818080808000"),
+		msg: Message{
+			Tag{3, VarintType}, Svarint(-1),
+			Tag{3, VarintType}, Denormalized{5, Svarint(-1)},
+			Tag{3, BytesType}, LengthPrefix{Svarint(math.MinInt64), Svarint(math.MaxInt64), Denormalized{5, Svarint(-1)}},
+		},
+		wantOutMulti: `Message{
+	Tag{3, Varint}, Svarint(-1),
+	Tag{3, Varint}, Denormalized{+5, Svarint(-1)},
+	Tag{3, Bytes}, LengthPrefix{Svarint(-9223372036854775808), Svarint(9223372036854775807), Denormalized{+5, Svarint(-1)}},
+}`,
+	}, {
+		raw: dhex("200120818080808000221100ffffffffffffffffff01818080808000"),
+		msg: Message{
+			Tag{4, VarintType}, Uvarint(+1),
+			Tag{4, VarintType}, Denormalized{5, Uvarint(+1)},
+			Tag{4, BytesType}, LengthPrefix{Uvarint(0), Uvarint(math.MaxUint64), Denormalized{5, Uvarint(+1)}},
+		},
+		wantOutSource: `pack.Message{
+	pack.Tag{4, pack.VarintType}, pack.Uvarint(1),
+	pack.Tag{4, pack.VarintType}, pack.Denormalized{+5, pack.Uvarint(1)},
+	pack.Tag{4, pack.BytesType}, pack.LengthPrefix{pack.Uvarint(0), pack.Uvarint(18446744073709551615), pack.Denormalized{+5, pack.Uvarint(1)}},
+}`,
+	}, {
+		raw: dhex("2d010000002a0800000000ffffffff"),
+		msg: Message{
+			Tag{5, Fixed32Type}, Uint32(+1),
+			Tag{5, BytesType}, LengthPrefix{Uint32(0), Uint32(math.MaxUint32)},
+		},
+		wantOutCompact: `Message{Tag{5, Fixed32}, Uint32(1), Tag{5, Bytes}, LengthPrefix{Uint32(0), Uint32(4294967295)}}`,
+	}, {
+		raw: dhex("35ffffffff320800000080ffffff7f"),
+		msg: Message{
+			Tag{6, Fixed32Type}, Int32(-1),
+			Tag{6, BytesType}, LengthPrefix{Int32(math.MinInt32), Int32(math.MaxInt32)},
+		},
+		wantOutMulti: `Message{
+	Tag{6, Fixed32}, Int32(-1),
+	Tag{6, Bytes}, LengthPrefix{Int32(-2147483648), Int32(2147483647)},
+}`,
+	}, {
+		raw: dhex("3ddb0f49403a1401000000ffff7f7f0000c07f0000807f000080ff"),
+		msg: Message{
+			Tag{7, Fixed32Type}, Float32(math.Pi),
+			Tag{7, BytesType}, LengthPrefix{Float32(math.SmallestNonzeroFloat32), Float32(math.MaxFloat32), Float32(math.NaN()), Float32(math.Inf(+1)), Float32(math.Inf(-1))},
+		},
+		wantOutSource: `pack.Message{
+	pack.Tag{7, pack.Fixed32Type}, pack.Float32(3.1415927),
+	pack.Tag{7, pack.BytesType}, pack.LengthPrefix{pack.Float32(1e-45), pack.Float32(3.4028235e+38), pack.Float32(math.NaN()), pack.Float32(math.Inf(+1)), pack.Float32(math.Inf(-1))},
+}`,
+	}, {
+		raw: dhex("41010000000000000042100000000000000000ffffffffffffffff"),
+		msg: Message{
+			Tag{8, Fixed64Type}, Uint64(+1),
+			Tag{8, BytesType}, LengthPrefix{Uint64(0), Uint64(math.MaxUint64)},
+		},
+		wantOutCompact: `Message{Tag{8, Fixed64}, Uint64(1), Tag{8, Bytes}, LengthPrefix{Uint64(0), Uint64(18446744073709551615)}}`,
+	}, {
+		raw: dhex("49ffffffffffffffff4a100000000000000080ffffffffffffff7f"),
+		msg: Message{
+			Tag{9, Fixed64Type}, Int64(-1),
+			Tag{9, BytesType}, LengthPrefix{Int64(math.MinInt64), Int64(math.MaxInt64)},
+		},
+		wantOutMulti: `Message{
+	Tag{9, Fixed64}, Int64(-1),
+	Tag{9, Bytes}, LengthPrefix{Int64(-9223372036854775808), Int64(9223372036854775807)},
+}`,
+	}, {
+		raw: dhex("51182d4454fb21094052280100000000000000ffffffffffffef7f010000000000f87f000000000000f07f000000000000f0ff"),
+		msg: Message{
+			Tag{10, Fixed64Type}, Float64(math.Pi),
+			Tag{10, BytesType}, LengthPrefix{Float64(math.SmallestNonzeroFloat64), Float64(math.MaxFloat64), Float64(math.NaN()), Float64(math.Inf(+1)), Float64(math.Inf(-1))},
+		},
+		wantOutMulti: `Message{
+	Tag{10, Fixed64}, Float64(3.141592653589793),
+	Tag{10, Bytes}, LengthPrefix{Float64(5e-324), Float64(1.7976931348623157e+308), Float64(NaN), Float64(+Inf), Float64(-Inf)},
+}`,
+	}, {
+		raw: dhex("5a06737472696e675a868080808000737472696e67"),
+		msg: Message{
+			Tag{11, BytesType}, String("string"),
+			Tag{11, BytesType}, Denormalized{+5, String("string")},
+		},
+		wantOutCompact: `Message{Tag{11, Bytes}, String("string"), Tag{11, Bytes}, Denormalized{+5, String("string")}}`,
+	}, {
+		raw: dhex("62056279746573628580808080006279746573"),
+		msg: Message{
+			Tag{12, BytesType}, Bytes("bytes"),
+			Tag{12, BytesType}, Denormalized{+5, Bytes("bytes")},
+		},
+		wantOutMulti: `Message{
+	Tag{12, Bytes}, Bytes("bytes"),
+	Tag{12, Bytes}, Denormalized{+5, Bytes("bytes")},
+}`,
+	}, {
+		raw: dhex("6a28a006ffffffffffffffffff01a506ffffffffa106ffffffffffffffffa206056279746573a306a406"),
+		msg: Message{
+			Tag{13, BytesType}, LengthPrefix(Message{
+				Tag{100, VarintType}, Uvarint(math.MaxUint64),
+				Tag{100, Fixed32Type}, Uint32(math.MaxUint32),
+				Tag{100, Fixed64Type}, Uint64(math.MaxUint64),
+				Tag{100, BytesType}, Bytes("bytes"),
+				Tag{100, StartGroupType}, Tag{100, EndGroupType},
+			}),
+		},
+		wantOutSource: `pack.Message{
+	pack.Tag{13, pack.BytesType}, pack.LengthPrefix(pack.Message{
+		pack.Tag{100, pack.VarintType}, pack.Uvarint(18446744073709551615),
+		pack.Tag{100, pack.Fixed32Type}, pack.Uint32(4294967295),
+		pack.Tag{100, pack.Fixed64Type}, pack.Uint64(18446744073709551615),
+		pack.Tag{100, pack.BytesType}, pack.Bytes("bytes"),
+		pack.Tag{100, pack.StartGroupType},
+		pack.Tag{100, pack.EndGroupType},
+	}),
+}`,
+	}, {
+		raw: dhex("6aa88080808000a006ffffffffffffffffff01a506ffffffffa106ffffffffffffffffa206056279746573a306a406"),
+		msg: Message{
+			Tag{13, BytesType}, Denormalized{5, LengthPrefix(Message{
+				Tag{100, VarintType}, Uvarint(math.MaxUint64),
+				Tag{100, Fixed32Type}, Uint32(math.MaxUint32),
+				Tag{100, Fixed64Type}, Uint64(math.MaxUint64),
+				Tag{100, BytesType}, Bytes("bytes"),
+				Tag{100, StartGroupType}, Tag{100, EndGroupType},
+			})},
+		},
+		wantOutCompact: `Message{Tag{13, Bytes}, Denormalized{+5, LengthPrefix(Message{Tag{100, Varint}, Uvarint(18446744073709551615), Tag{100, Fixed32}, Uint32(4294967295), Tag{100, Fixed64}, Uint64(18446744073709551615), Tag{100, Bytes}, Bytes("bytes"), Tag{100, StartGroup}, Tag{100, EndGroup}})}}`,
+	}, {
+		raw: dhex("73a006ffffffffffffffffff01a506ffffffffa106ffffffffffffffffa206056279746573a306a40674"),
+		msg: Message{
+			Tag{14, StartGroupType}, Message{
+				Tag{100, VarintType}, Uvarint(math.MaxUint64),
+				Tag{100, Fixed32Type}, Uint32(math.MaxUint32),
+				Tag{100, Fixed64Type}, Uint64(math.MaxUint64),
+				Tag{100, BytesType}, Bytes("bytes"),
+				Tag{100, StartGroupType}, Tag{100, EndGroupType},
+			},
+			Tag{14, EndGroupType},
+		},
+		wantOutMulti: `Message{
+	Tag{14, StartGroup},
+	Message{
+		Tag{100, Varint}, Uvarint(18446744073709551615),
+		Tag{100, Fixed32}, Uint32(4294967295),
+		Tag{100, Fixed64}, Uint64(18446744073709551615),
+		Tag{100, Bytes}, Bytes("bytes"),
+		Tag{100, StartGroup},
+		Tag{100, EndGroup},
+	},
+	Tag{14, EndGroup},
+}`,
+	}, {
+		raw: dhex("d0faa972cd02a5f09051c2d8aa0d6a26a89c311eddef024b423c0f6f47b64227a1600db56e3f73d4113096c9a88e2b99f2d847516853d76a1a6e9811c85a2ab3"),
+		msg: Message{
+			Tag{29970346, VarintType}, Uvarint(333),
+			Tag{21268228, Fixed32Type}, Uint32(229300418),
+			Tag{13, BytesType}, LengthPrefix(Message{
+				Tag{100805, VarintType}, Uvarint(30),
+				Tag{5883, Fixed32Type}, Uint32(255607371),
+				Tag{13, Type(7)},
+				Raw("G\xb6B'\xa1`\r\xb5n?s\xd4\x110\x96ɨ\x8e+\x99\xf2\xd8GQhS"),
+			}),
+			Tag{1706, Type(7)},
+			Raw("\x1an\x98\x11\xc8Z*\xb3"),
+		},
+	}, {
+		raw: dhex("3d08d0e57f"),
+		msg: Message{
+			Tag{7, Fixed32Type}, Float32(math.Float32frombits(
+				// TODO: Remove workaround for compiler bug (see https://golang.org/issues/27193).
+				func() uint32 { return 0x7fe5d008 }(),
+			)),
+		},
+		wantOutSource: `pack.Message{
+	pack.Tag{7, pack.Fixed32Type}, pack.Float32(math.Float32frombits(0x7fe5d008)),
+}`,
+	}, {
+		raw: dhex("51a8d65110771bf97f"),
+		msg: Message{
+			Tag{10, Fixed64Type}, Float64(math.Float64frombits(0x7ff91b771051d6a8)),
+		},
+		wantOutSource: `pack.Message{
+	pack.Tag{10, pack.Fixed64Type}, pack.Float64(math.Float64frombits(0x7ff91b771051d6a8)),
+}`,
+	}, {
+		raw: dhex("ab2c14481ab3e9a76d937fb4dd5e6c616ef311f62b7fe888785fca5609ffe81c1064e50dd7a9edb408d317e2891c0d54c719446938d41ab0ccf8e61dc28b0ebb"),
+		msg: Message{
+			Tag{709, StartGroupType},
+			Tag{2, EndGroupType},
+			Tag{9, VarintType}, Uvarint(26),
+			Tag{28655254, StartGroupType},
+			Message{
+				Tag{2034, StartGroupType},
+				Tag{194006, EndGroupType},
+			},
+			Tag{13, EndGroupType},
+			Tag{12, Fixed64Type}, Uint64(9865274810543764334),
+			Tag{15, VarintType}, Uvarint(95),
+			Tag{1385, BytesType}, Bytes("\xff\xe8\x1c\x10d\xe5\rש"),
+			Tag{17229, Fixed32Type}, Uint32(2313295827),
+			Tag{3, EndGroupType},
+			Tag{1, Fixed32Type}, Uint32(1142540116),
+			Tag{13, Fixed64Type}, Uint64(2154683029754926136),
+			Tag{28856, BytesType},
+			Raw("\xbb"),
+		},
+	}, {
+		raw: dhex("29baa4ac1c1e0a20183393bac434b8d3559337ec940050038770eaa9937f98e4"),
+		msg: Message{
+			Tag{5, Fixed64Type}, Uint64(1738400580611384506),
+			Tag{6, StartGroupType},
+			Message{
+				Tag{13771682, StartGroupType},
+				Message{
+					Tag{175415, VarintType}, Uvarint(7059),
+				},
+				Denormalized{+1, Tag{333, EndGroupType}},
+				Tag{10, VarintType}, Uvarint(3),
+				Tag{1792, Type(7)},
+				Raw("꩓\u007f\x98\xe4"),
+			},
+		},
+	}}
+
+	equateFloatBits := cmp.Options{
+		cmp.Comparer(func(x, y Float32) bool {
+			return math.Float32bits(float32(x)) == math.Float32bits(float32(y))
+		}),
+		cmp.Comparer(func(x, y Float64) bool {
+			return math.Float64bits(float64(x)) == math.Float64bits(float64(y))
+		}),
+	}
+	for _, tt := range tests {
+		t.Run("", func(t *testing.T) {
+			var msg Message
+			raw := tt.msg.Marshal()
+			msg.UnmarshalDescriptor(tt.raw, msgDesc)
+
+			if !bytes.Equal(raw, tt.raw) {
+				t.Errorf("Marshal() mismatch:\ngot  %x\nwant %x", raw, tt.raw)
+			}
+			if !cmp.Equal(msg, tt.msg, equateFloatBits) {
+				t.Errorf("Unmarshal() mismatch:\ngot  %+v\nwant %+v", msg, tt.msg)
+			}
+			if got, want := tt.msg.Size(), len(tt.raw); got != want {
+				t.Errorf("Size() = %v, want %v", got, want)
+			}
+			if tt.wantOutCompact != "" {
+				gotOut := fmt.Sprintf("%v", tt.msg)
+				if string(gotOut) != tt.wantOutCompact {
+					t.Errorf("fmt.Sprintf(%q, msg):\ngot:  %s\nwant: %s", "%v", gotOut, tt.wantOutCompact)
+				}
+			}
+			if tt.wantOutMulti != "" {
+				gotOut := fmt.Sprintf("%+v", tt.msg)
+				if string(gotOut) != tt.wantOutMulti {
+					t.Errorf("fmt.Sprintf(%q, msg):\ngot:  %s\nwant: %s", "%+v", gotOut, tt.wantOutMulti)
+				}
+			}
+			if tt.wantOutSource != "" {
+				gotOut := fmt.Sprintf("%#v", tt.msg)
+				if string(gotOut) != tt.wantOutSource {
+					t.Errorf("fmt.Sprintf(%q, msg):\ngot:  %s\nwant: %s", "%#v", gotOut, tt.wantOutSource)
+				}
+			}
+		})
+	}
+}