protowire.ConsumeVarint - Code Metrics - Inspection of "Adding vendor folder" - cdleo/go-sqldb - Measure and Improve Code Quality continuously with Scrutinizer

Test Failed

Branch — main (436074)

by Christian

created 2022-06-16 19:46 UTC

protowire.ConsumeVarint F

↳ Parent: vendor/google.golang.org/protobuf/encoding/protowire/wire.go

Complexity

Conditions

Size

Total Lines	100
Code Lines	71

Duplication

Lines	0
Ratio	0 %

Importance

Changes

Metric	Value
cc	21
eloc	71
nop	1
dl	0
loc	100
rs	0
c	0
b	0
f	0

How to fix Long Method Complexity

// 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 protowire parses and formats the raw wire encoding.
// See https://developers.google.com/protocol-buffers/docs/encoding.
//
// For marshaling and unmarshaling entire protobuf messages,
// use the "google.golang.org/protobuf/proto" package instead.
package protowire

import (
	"io"
	"math"
	"math/bits"

	"google.golang.org/protobuf/internal/errors"
)

// Number represents the field number.
type Number int32

const (
	MinValidNumber        Number = 1
	FirstReservedNumber   Number = 19000
	LastReservedNumber    Number = 19999
	MaxValidNumber        Number = 1<<29 - 1
	DefaultRecursionLimit        = 10000
)

// IsValid reports whether the field number is semantically valid.
//
// Note that while numbers within the reserved range are semantically invalid,
// they are syntactically valid in the wire format.
// Implementations may treat records with reserved field numbers as unknown.
func (n Number) IsValid() bool {
	return MinValidNumber <= n && n < FirstReservedNumber || LastReservedNumber < n && n <= MaxValidNumber
}

// Type represents the wire type.
type Type int8

const (
	VarintType     Type = 0
	Fixed32Type    Type = 5
	Fixed64Type    Type = 1
	BytesType      Type = 2
	StartGroupType Type = 3
	EndGroupType   Type = 4
)

const (
	_ = -iota
	errCodeTruncated
	errCodeFieldNumber
	errCodeOverflow
	errCodeReserved
	errCodeEndGroup
	errCodeRecursionDepth
)

var (
	errFieldNumber = errors.New("invalid field number")
	errOverflow    = errors.New("variable length integer overflow")
	errReserved    = errors.New("cannot parse reserved wire type")
	errEndGroup    = errors.New("mismatching end group marker")
	errParse       = errors.New("parse error")
)

// ParseError converts an error code into an error value.
// This returns nil if n is a non-negative number.
func ParseError(n int) error {
	if n >= 0 {
		return nil
	}
	switch n {
	case errCodeTruncated:
		return io.ErrUnexpectedEOF
	case errCodeFieldNumber:
		return errFieldNumber
	case errCodeOverflow:
		return errOverflow
	case errCodeReserved:
		return errReserved
	case errCodeEndGroup:
		return errEndGroup
	default:
		return errParse
	}
}

// ConsumeField parses an entire field record (both tag and value) and returns
// the field number, the wire type, and the total length.
// This returns a negative length upon an error (see ParseError).
//
// The total length includes the tag header and the end group marker (if the
// field is a group).
func ConsumeField(b []byte) (Number, Type, int) {
	num, typ, n := ConsumeTag(b)
	if n < 0 {
		return 0, 0, n // forward error code
	}
	m := ConsumeFieldValue(num, typ, b[n:])
	if m < 0 {
		return 0, 0, m // forward error code
	}
	return num, typ, n + m
}

// ConsumeFieldValue parses a field value and returns its length.
// This assumes that the field Number and wire Type have already been parsed.
// This returns a negative length upon an error (see ParseError).
//
// When parsing a group, the length includes the end group marker and
// the end group is verified to match the starting field number.
func ConsumeFieldValue(num Number, typ Type, b []byte) (n int) {
	return consumeFieldValueD(num, typ, b, DefaultRecursionLimit)
}

func consumeFieldValueD(num Number, typ Type, b []byte, depth int) (n int) {
	switch typ {
	case VarintType:
		_, n = ConsumeVarint(b)
		return n
	case Fixed32Type:
		_, n = ConsumeFixed32(b)
		return n
	case Fixed64Type:
		_, n = ConsumeFixed64(b)
		return n
	case BytesType:
		_, n = ConsumeBytes(b)
		return n
	case StartGroupType:
		if depth < 0 {
			return errCodeRecursionDepth
		}
		n0 := len(b)
		for {
			num2, typ2, n := ConsumeTag(b)
			if n < 0 {
				return n // forward error code
			}
			b = b[n:]
			if typ2 == EndGroupType {
				if num != num2 {
					return errCodeEndGroup
				}
				return n0 - len(b)
			}

			n = consumeFieldValueD(num2, typ2, b, depth-1)
			if n < 0 {
				return n // forward error code
			}
			b = b[n:]
		}
	case EndGroupType:
		return errCodeEndGroup
	default:
		return errCodeReserved
	}
}

// AppendTag encodes num and typ as a varint-encoded tag and appends it to b.
func AppendTag(b []byte, num Number, typ Type) []byte {
	return AppendVarint(b, EncodeTag(num, typ))
}

// ConsumeTag parses b as a varint-encoded tag, reporting its length.
// This returns a negative length upon an error (see ParseError).
func ConsumeTag(b []byte) (Number, Type, int) {
	v, n := ConsumeVarint(b)
	if n < 0 {
		return 0, 0, n // forward error code
	}
	num, typ := DecodeTag(v)
	if num < MinValidNumber {
		return 0, 0, errCodeFieldNumber
	}
	return num, typ, n
}

func SizeTag(num Number) int {
	return SizeVarint(EncodeTag(num, 0)) // wire type has no effect on size
}

// AppendVarint appends v to b as a varint-encoded uint64.
func AppendVarint(b []byte, v uint64) []byte {
	switch {
	case v < 1<<7:
		b = append(b, byte(v))
	case v < 1<<14:
		b = append(b,
			byte((v>>0)&0x7f|0x80),
			byte(v>>7))
	case v < 1<<21:
		b = append(b,
			byte((v>>0)&0x7f|0x80),
			byte((v>>7)&0x7f|0x80),
			byte(v>>14))
	case v < 1<<28:
		b = append(b,
			byte((v>>0)&0x7f|0x80),
			byte((v>>7)&0x7f|0x80),
			byte((v>>14)&0x7f|0x80),
			byte(v>>21))
	case v < 1<<35:
		b = append(b,
			byte((v>>0)&0x7f|0x80),
			byte((v>>7)&0x7f|0x80),
			byte((v>>14)&0x7f|0x80),
			byte((v>>21)&0x7f|0x80),
			byte(v>>28))
	case v < 1<<42:
		b = append(b,
			byte((v>>0)&0x7f|0x80),
			byte((v>>7)&0x7f|0x80),
			byte((v>>14)&0x7f|0x80),
			byte((v>>21)&0x7f|0x80),
			byte((v>>28)&0x7f|0x80),
			byte(v>>35))
	case v < 1<<49:
		b = append(b,
			byte((v>>0)&0x7f|0x80),
			byte((v>>7)&0x7f|0x80),
			byte((v>>14)&0x7f|0x80),
			byte((v>>21)&0x7f|0x80),
			byte((v>>28)&0x7f|0x80),
			byte((v>>35)&0x7f|0x80),
			byte(v>>42))
	case v < 1<<56:
		b = append(b,
			byte((v>>0)&0x7f|0x80),
			byte((v>>7)&0x7f|0x80),
			byte((v>>14)&0x7f|0x80),
			byte((v>>21)&0x7f|0x80),
			byte((v>>28)&0x7f|0x80),
			byte((v>>35)&0x7f|0x80),
			byte((v>>42)&0x7f|0x80),
			byte(v>>49))
	case v < 1<<63:
		b = append(b,
			byte((v>>0)&0x7f|0x80),
			byte((v>>7)&0x7f|0x80),
			byte((v>>14)&0x7f|0x80),
			byte((v>>21)&0x7f|0x80),
			byte((v>>28)&0x7f|0x80),
			byte((v>>35)&0x7f|0x80),
			byte((v>>42)&0x7f|0x80),
			byte((v>>49)&0x7f|0x80),
			byte(v>>56))
	default:
		b = append(b,
			byte((v>>0)&0x7f|0x80),
			byte((v>>7)&0x7f|0x80),
			byte((v>>14)&0x7f|0x80),
			byte((v>>21)&0x7f|0x80),
			byte((v>>28)&0x7f|0x80),
			byte((v>>35)&0x7f|0x80),
			byte((v>>42)&0x7f|0x80),
			byte((v>>49)&0x7f|0x80),
			byte((v>>56)&0x7f|0x80),
			1)
	}
	return b
}

// ConsumeVarint parses b as a varint-encoded uint64, reporting its length.
// This returns a negative length upon an error (see ParseError).
func ConsumeVarint(b []byte) (v uint64, n int) {
	var y uint64
	if len(b) <= 0 {
		return 0, errCodeTruncated
	}
	v = uint64(b[0])
	if v < 0x80 {
		return v, 1
	}
	v -= 0x80

	if len(b) <= 1 {
		return 0, errCodeTruncated
	}
	y = uint64(b[1])
	v += y << 7
	if y < 0x80 {
		return v, 2
	}
	v -= 0x80 << 7

	if len(b) <= 2 {
		return 0, errCodeTruncated
	}
	y = uint64(b[2])
	v += y << 14
	if y < 0x80 {
		return v, 3
	}
	v -= 0x80 << 14

	if len(b) <= 3 {
		return 0, errCodeTruncated
	}
	y = uint64(b[3])
	v += y << 21
	if y < 0x80 {
		return v, 4
	}
	v -= 0x80 << 21

	if len(b) <= 4 {
		return 0, errCodeTruncated
	}
	y = uint64(b[4])
	v += y << 28
	if y < 0x80 {
		return v, 5
	}
	v -= 0x80 << 28

	if len(b) <= 5 {
		return 0, errCodeTruncated
	}
	y = uint64(b[5])
	v += y << 35
	if y < 0x80 {
		return v, 6
	}
	v -= 0x80 << 35

	if len(b) <= 6 {
		return 0, errCodeTruncated
	}
	y = uint64(b[6])
	v += y << 42
	if y < 0x80 {
		return v, 7
	}
	v -= 0x80 << 42

	if len(b) <= 7 {
		return 0, errCodeTruncated
	}
	y = uint64(b[7])
	v += y << 49
	if y < 0x80 {
		return v, 8
	}
	v -= 0x80 << 49

	if len(b) <= 8 {
		return 0, errCodeTruncated
	}
	y = uint64(b[8])
	v += y << 56
	if y < 0x80 {
		return v, 9
	}
	v -= 0x80 << 56

	if len(b) <= 9 {
		return 0, errCodeTruncated
	}
	y = uint64(b[9])
	v += y << 63
	if y < 2 {
		return v, 10
	}
	return 0, errCodeOverflow
}

// SizeVarint returns the encoded size of a varint.
// The size is guaranteed to be within 1 and 10, inclusive.
func SizeVarint(v uint64) int {
	// This computes 1 + (bits.Len64(v)-1)/7.
	// 9/64 is a good enough approximation of 1/7
	return int(9*uint32(bits.Len64(v))+64) / 64
}

// AppendFixed32 appends v to b as a little-endian uint32.
func AppendFixed32(b []byte, v uint32) []byte {
	return append(b,
		byte(v>>0),
		byte(v>>8),
		byte(v>>16),
		byte(v>>24))
}

// ConsumeFixed32 parses b as a little-endian uint32, reporting its length.
// This returns a negative length upon an error (see ParseError).
func ConsumeFixed32(b []byte) (v uint32, n int) {
	if len(b) < 4 {
		return 0, errCodeTruncated
	}
	v = uint32(b[0])<<0 | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
	return v, 4
}

// SizeFixed32 returns the encoded size of a fixed32; which is always 4.
func SizeFixed32() int {
	return 4
}

// AppendFixed64 appends v to b as a little-endian uint64.
func AppendFixed64(b []byte, v uint64) []byte {
	return append(b,
		byte(v>>0),
		byte(v>>8),
		byte(v>>16),
		byte(v>>24),
		byte(v>>32),
		byte(v>>40),
		byte(v>>48),
		byte(v>>56))
}

// ConsumeFixed64 parses b as a little-endian uint64, reporting its length.
// This returns a negative length upon an error (see ParseError).
func ConsumeFixed64(b []byte) (v uint64, n int) {
	if len(b) < 8 {
		return 0, errCodeTruncated
	}
	v = uint64(b[0])<<0 | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 | uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
	return v, 8
}

// SizeFixed64 returns the encoded size of a fixed64; which is always 8.
func SizeFixed64() int {
	return 8
}

// AppendBytes appends v to b as a length-prefixed bytes value.
func AppendBytes(b []byte, v []byte) []byte {
	return append(AppendVarint(b, uint64(len(v))), v...)
}

// ConsumeBytes parses b as a length-prefixed bytes value, reporting its length.
// This returns a negative length upon an error (see ParseError).
func ConsumeBytes(b []byte) (v []byte, n int) {
	m, n := ConsumeVarint(b)
	if n < 0 {
		return nil, n // forward error code
	}
	if m > uint64(len(b[n:])) {
		return nil, errCodeTruncated
	}
	return b[n:][:m], n + int(m)
}

// SizeBytes returns the encoded size of a length-prefixed bytes value,
// given only the length.
func SizeBytes(n int) int {
	return SizeVarint(uint64(n)) + n
}

// AppendString appends v to b as a length-prefixed bytes value.
func AppendString(b []byte, v string) []byte {
	return append(AppendVarint(b, uint64(len(v))), v...)
}

// ConsumeString parses b as a length-prefixed bytes value, reporting its length.
// This returns a negative length upon an error (see ParseError).
func ConsumeString(b []byte) (v string, n int) {
	bb, n := ConsumeBytes(b)
	return string(bb), n
}

// AppendGroup appends v to b as group value, with a trailing end group marker.
// The value v must not contain the end marker.
func AppendGroup(b []byte, num Number, v []byte) []byte {
	return AppendVarint(append(b, v...), EncodeTag(num, EndGroupType))
}

// ConsumeGroup parses b as a group value until the trailing end group marker,
// and verifies that the end marker matches the provided num. The value v
// does not contain the end marker, while the length does contain the end marker.
// This returns a negative length upon an error (see ParseError).
func ConsumeGroup(num Number, b []byte) (v []byte, n int) {
	n = ConsumeFieldValue(num, StartGroupType, b)
	if n < 0 {
		return nil, n // forward error code
	}
	b = b[:n]

	// Truncate off end group marker, but need to handle denormalized varints.
	// Assuming end marker is never 0 (which is always the case since
	// EndGroupType is non-zero), we can truncate all trailing bytes where the
	// lower 7 bits are all zero (implying that the varint is denormalized).
	for len(b) > 0 && b[len(b)-1]&0x7f == 0 {
		b = b[:len(b)-1]
	}
	b = b[:len(b)-SizeTag(num)]
	return b, n
}

// SizeGroup returns the encoded size of a group, given only the length.
func SizeGroup(num Number, n int) int {
	return n + SizeTag(num)
}

// DecodeTag decodes the field Number and wire Type from its unified form.
// The Number is -1 if the decoded field number overflows int32.
// Other than overflow, this does not check for field number validity.
func DecodeTag(x uint64) (Number, Type) {
	// NOTE: MessageSet allows for larger field numbers than normal.
	if x>>3 > uint64(math.MaxInt32) {
		return -1, 0
	}
	return Number(x >> 3), Type(x & 7)
}

// EncodeTag encodes the field Number and wire Type into its unified form.
func EncodeTag(num Number, typ Type) uint64 {
	return uint64(num)<<3 | uint64(typ&7)
}

// DecodeZigZag decodes a zig-zag-encoded uint64 as an int64.
//	Input:  {…,  5,  3,  1,  0,  2,  4,  6, …}
//	Output: {…, -3, -2, -1,  0, +1, +2, +3, …}
func DecodeZigZag(x uint64) int64 {
	return int64(x>>1) ^ int64(x)<<63>>63
}

// EncodeZigZag encodes an int64 as a zig-zag-encoded uint64.
//	Input:  {…, -3, -2, -1,  0, +1, +2, +3, …}
//	Output: {…,  5,  3,  1,  0,  2,  4,  6, …}
func EncodeZigZag(x int64) uint64 {
	return uint64(x<<1) ^ uint64(x>>63)
}

// DecodeBool decodes a uint64 as a bool.
//	Input:  {    0,    1,    2, …}
//	Output: {false, true, true, …}
func DecodeBool(x uint64) bool {
	return x != 0
}

// EncodeBool encodes a bool as a uint64.
//	Input:  {false, true}
//	Output: {    0,    1}
func EncodeBool(x bool) uint64 {
	if x {
		return 1
	}
	return 0
}


1			// Copyright 2018 The Go Authors. All rights reserved.
2			// Use of this source code is governed by a BSD-style
3			// license that can be found in the LICENSE file.
4
5			// Package protowire parses and formats the raw wire encoding.
6			// See https://developers.google.com/protocol-buffers/docs/encoding.
7			//
8			// For marshaling and unmarshaling entire protobuf messages,
9			// use the "google.golang.org/protobuf/proto" package instead.
10			package protowire
11
12			import (
13			"io"
14			"math"
15			"math/bits"
16
17			"google.golang.org/protobuf/internal/errors"
18			)
19
20			// Number represents the field number.
21			type Number int32
22
23			const (
24			MinValidNumber Number = 1
25			FirstReservedNumber Number = 19000
26			LastReservedNumber Number = 19999
27			MaxValidNumber Number = 1<<29 - 1
28			DefaultRecursionLimit = 10000
29			)
30
31			// IsValid reports whether the field number is semantically valid.
32			//
33			// Note that while numbers within the reserved range are semantically invalid,
34			// they are syntactically valid in the wire format.
35			// Implementations may treat records with reserved field numbers as unknown.
36			func (n Number) IsValid() bool {
37			return MinValidNumber <= n && n < FirstReservedNumber \|\| LastReservedNumber < n && n <= MaxValidNumber
38			}
39
40			// Type represents the wire type.
41			type Type int8
42
43			const (
44			VarintType Type = 0
45			Fixed32Type Type = 5
46			Fixed64Type Type = 1
47			BytesType Type = 2
48			StartGroupType Type = 3
49			EndGroupType Type = 4
50			)
51
52			const (
53			_ = -iota
54			errCodeTruncated
55			errCodeFieldNumber
56			errCodeOverflow
57			errCodeReserved
58			errCodeEndGroup
59			errCodeRecursionDepth
60			)
61
62			var (
63			errFieldNumber = errors.New("invalid field number")
64			errOverflow = errors.New("variable length integer overflow")
65			errReserved = errors.New("cannot parse reserved wire type")
66			errEndGroup = errors.New("mismatching end group marker")
67			errParse = errors.New("parse error")
68			)
69
70			// ParseError converts an error code into an error value.
71			// This returns nil if n is a non-negative number.
72			func ParseError(n int) error {
73			if n >= 0 {
74			return nil
75			}
76			switch n {
77			case errCodeTruncated:
78			return io.ErrUnexpectedEOF
79			case errCodeFieldNumber:
80			return errFieldNumber
81			case errCodeOverflow:
82			return errOverflow
83			case errCodeReserved:
84			return errReserved
85			case errCodeEndGroup:
86			return errEndGroup
87			default:
88			return errParse
89			}
90			}
91
92			// ConsumeField parses an entire field record (both tag and value) and returns
93			// the field number, the wire type, and the total length.
94			// This returns a negative length upon an error (see ParseError).
95			//
96			// The total length includes the tag header and the end group marker (if the
97			// field is a group).
98			func ConsumeField(b []byte) (Number, Type, int) {
99			num, typ, n := ConsumeTag(b)
100			if n < 0 {
101			return 0, 0, n // forward error code
102			}
103			m := ConsumeFieldValue(num, typ, b[n:])
104			if m < 0 {
105			return 0, 0, m // forward error code
106			}
107			return num, typ, n + m
108			}
109
110			// ConsumeFieldValue parses a field value and returns its length.
111			// This assumes that the field Number and wire Type have already been parsed.
112			// This returns a negative length upon an error (see ParseError).
113			//
114			// When parsing a group, the length includes the end group marker and
115			// the end group is verified to match the starting field number.
116			func ConsumeFieldValue(num Number, typ Type, b []byte) (n int) {
117			return consumeFieldValueD(num, typ, b, DefaultRecursionLimit)
118			}
119
120			func consumeFieldValueD(num Number, typ Type, b []byte, depth int) (n int) {
121			switch typ {
122			case VarintType:
123			_, n = ConsumeVarint(b)
124			return n
125			case Fixed32Type:
126			_, n = ConsumeFixed32(b)
127			return n
128			case Fixed64Type:
129			_, n = ConsumeFixed64(b)
130			return n
131			case BytesType:
132			_, n = ConsumeBytes(b)
133			return n
134			case StartGroupType:
135			if depth < 0 {
136			return errCodeRecursionDepth
137			}
138			n0 := len(b)
139			for {
140			num2, typ2, n := ConsumeTag(b)
141			if n < 0 {
142			return n // forward error code
143			}
144			b = b[n:]
145			if typ2 == EndGroupType {
146			if num != num2 {
147			return errCodeEndGroup
148			}
149			return n0 - len(b)
150			}
151
152			n = consumeFieldValueD(num2, typ2, b, depth-1)
153			if n < 0 {
154			return n // forward error code
155			}
156			b = b[n:]
157			}
158			case EndGroupType:
159			return errCodeEndGroup
160			default:
161			return errCodeReserved
162			}
163			}
164
165			// AppendTag encodes num and typ as a varint-encoded tag and appends it to b.
166			func AppendTag(b []byte, num Number, typ Type) []byte {
167			return AppendVarint(b, EncodeTag(num, typ))
168			}
169
170			// ConsumeTag parses b as a varint-encoded tag, reporting its length.
171			// This returns a negative length upon an error (see ParseError).
172			func ConsumeTag(b []byte) (Number, Type, int) {
173			v, n := ConsumeVarint(b)
174			if n < 0 {
175			return 0, 0, n // forward error code
176			}
177			num, typ := DecodeTag(v)
178			if num < MinValidNumber {
179			return 0, 0, errCodeFieldNumber
180			}
181			return num, typ, n
182			}
183
184			func SizeTag(num Number) int {
185			return SizeVarint(EncodeTag(num, 0)) // wire type has no effect on size
186			}
187
188			// AppendVarint appends v to b as a varint-encoded uint64.
189			func AppendVarint(b []byte, v uint64) []byte {
190			switch {
191			case v < 1<<7:
192			b = append(b, byte(v))
193			case v < 1<<14:
194			b = append(b,
195			byte((v>>0)&0x7f\|0x80),
196			byte(v>>7))
197			case v < 1<<21:
198			b = append(b,
199			byte((v>>0)&0x7f\|0x80),
200			byte((v>>7)&0x7f\|0x80),
201			byte(v>>14))
202			case v < 1<<28:
203			b = append(b,
204			byte((v>>0)&0x7f\|0x80),
205			byte((v>>7)&0x7f\|0x80),
206			byte((v>>14)&0x7f\|0x80),
207			byte(v>>21))
208			case v < 1<<35:
209			b = append(b,
210			byte((v>>0)&0x7f\|0x80),
211			byte((v>>7)&0x7f\|0x80),
212			byte((v>>14)&0x7f\|0x80),
213			byte((v>>21)&0x7f\|0x80),
214			byte(v>>28))
215			case v < 1<<42:
216			b = append(b,
217			byte((v>>0)&0x7f\|0x80),
218			byte((v>>7)&0x7f\|0x80),
219			byte((v>>14)&0x7f\|0x80),
220			byte((v>>21)&0x7f\|0x80),
221			byte((v>>28)&0x7f\|0x80),
222			byte(v>>35))
223			case v < 1<<49:
224			b = append(b,
225			byte((v>>0)&0x7f\|0x80),
226			byte((v>>7)&0x7f\|0x80),
227			byte((v>>14)&0x7f\|0x80),
228			byte((v>>21)&0x7f\|0x80),
229			byte((v>>28)&0x7f\|0x80),
230			byte((v>>35)&0x7f\|0x80),
231			byte(v>>42))
232			case v < 1<<56:
233			b = append(b,
234			byte((v>>0)&0x7f\|0x80),
235			byte((v>>7)&0x7f\|0x80),
236			byte((v>>14)&0x7f\|0x80),
237			byte((v>>21)&0x7f\|0x80),
238			byte((v>>28)&0x7f\|0x80),
239			byte((v>>35)&0x7f\|0x80),
240			byte((v>>42)&0x7f\|0x80),
241			byte(v>>49))
242			case v < 1<<63:
243			b = append(b,
244			byte((v>>0)&0x7f\|0x80),
245			byte((v>>7)&0x7f\|0x80),
246			byte((v>>14)&0x7f\|0x80),
247			byte((v>>21)&0x7f\|0x80),
248			byte((v>>28)&0x7f\|0x80),
249			byte((v>>35)&0x7f\|0x80),
250			byte((v>>42)&0x7f\|0x80),
251			byte((v>>49)&0x7f\|0x80),
252			byte(v>>56))
253			default:
254			b = append(b,
255			byte((v>>0)&0x7f\|0x80),
256			byte((v>>7)&0x7f\|0x80),
257			byte((v>>14)&0x7f\|0x80),
258			byte((v>>21)&0x7f\|0x80),
259			byte((v>>28)&0x7f\|0x80),
260			byte((v>>35)&0x7f\|0x80),
261			byte((v>>42)&0x7f\|0x80),
262			byte((v>>49)&0x7f\|0x80),
263			byte((v>>56)&0x7f\|0x80),
264			1)
265			}
266			return b
267			}
268
269			// ConsumeVarint parses b as a varint-encoded uint64, reporting its length.
270			// This returns a negative length upon an error (see ParseError).
271			func ConsumeVarint(b []byte) (v uint64, n int) {
272			var y uint64
273			if len(b) <= 0 {
274			return 0, errCodeTruncated
275			}
276			v = uint64(b[0])
277			if v < 0x80 {
278			return v, 1
279			}
280			v -= 0x80
281
282			if len(b) <= 1 {
283			return 0, errCodeTruncated
284			}
285			y = uint64(b[1])
286			v += y << 7
287			if y < 0x80 {
288			return v, 2
289			}
290			v -= 0x80 << 7
291
292			if len(b) <= 2 {
293			return 0, errCodeTruncated
294			}
295			y = uint64(b[2])
296			v += y << 14
297			if y < 0x80 {
298			return v, 3
299			}
300			v -= 0x80 << 14
301
302			if len(b) <= 3 {
303			return 0, errCodeTruncated
304			}
305			y = uint64(b[3])
306			v += y << 21
307			if y < 0x80 {
308			return v, 4
309			}
310			v -= 0x80 << 21
311
312			if len(b) <= 4 {
313			return 0, errCodeTruncated
314			}
315			y = uint64(b[4])
316			v += y << 28
317			if y < 0x80 {
318			return v, 5
319			}
320			v -= 0x80 << 28
321
322			if len(b) <= 5 {
323			return 0, errCodeTruncated
324			}
325			y = uint64(b[5])
326			v += y << 35
327			if y < 0x80 {
328			return v, 6
329			}
330			v -= 0x80 << 35
331
332			if len(b) <= 6 {
333			return 0, errCodeTruncated
334			}
335			y = uint64(b[6])
336			v += y << 42
337			if y < 0x80 {
338			return v, 7
339			}
340			v -= 0x80 << 42
341
342			if len(b) <= 7 {
343			return 0, errCodeTruncated
344			}
345			y = uint64(b[7])
346			v += y << 49
347			if y < 0x80 {
348			return v, 8
349			}
350			v -= 0x80 << 49
351
352			if len(b) <= 8 {
353			return 0, errCodeTruncated
354			}
355			y = uint64(b[8])
356			v += y << 56
357			if y < 0x80 {
358			return v, 9
359			}
360			v -= 0x80 << 56
361
362			if len(b) <= 9 {
363			return 0, errCodeTruncated
364			}
365			y = uint64(b[9])
366			v += y << 63
367			if y < 2 {
368			return v, 10
369			}
370			return 0, errCodeOverflow
371			}
372
373			// SizeVarint returns the encoded size of a varint.
374			// The size is guaranteed to be within 1 and 10, inclusive.
375			func SizeVarint(v uint64) int {
376			// This computes 1 + (bits.Len64(v)-1)/7.
377			// 9/64 is a good enough approximation of 1/7
378			return int(9*uint32(bits.Len64(v))+64) / 64
379			}
380
381			// AppendFixed32 appends v to b as a little-endian uint32.
382			func AppendFixed32(b []byte, v uint32) []byte {
383			return append(b,
384			byte(v>>0),
385			byte(v>>8),
386			byte(v>>16),
387			byte(v>>24))
388			}
389
390			// ConsumeFixed32 parses b as a little-endian uint32, reporting its length.
391			// This returns a negative length upon an error (see ParseError).
392			func ConsumeFixed32(b []byte) (v uint32, n int) {
393			if len(b) < 4 {
394			return 0, errCodeTruncated
395			}
396			v = uint32(b[0])<<0 \| uint32(b[1])<<8 \| uint32(b[2])<<16 \| uint32(b[3])<<24
397			return v, 4
398			}
399
400			// SizeFixed32 returns the encoded size of a fixed32; which is always 4.
401			func SizeFixed32() int {
402			return 4
403			}
404
405			// AppendFixed64 appends v to b as a little-endian uint64.
406			func AppendFixed64(b []byte, v uint64) []byte {
407			return append(b,
408			byte(v>>0),
409			byte(v>>8),
410			byte(v>>16),
411			byte(v>>24),
412			byte(v>>32),
413			byte(v>>40),
414			byte(v>>48),
415			byte(v>>56))
416			}
417
418			// ConsumeFixed64 parses b as a little-endian uint64, reporting its length.
419			// This returns a negative length upon an error (see ParseError).
420			func ConsumeFixed64(b []byte) (v uint64, n int) {
421			if len(b) < 8 {
422			return 0, errCodeTruncated
423			}
424			v = uint64(b[0])<<0 \| uint64(b[1])<<8 \| uint64(b[2])<<16 \| uint64(b[3])<<24 \| uint64(b[4])<<32 \| uint64(b[5])<<40 \| uint64(b[6])<<48 \| uint64(b[7])<<56
425			return v, 8
426			}
427
428			// SizeFixed64 returns the encoded size of a fixed64; which is always 8.
429			func SizeFixed64() int {
430			return 8
431			}
432
433			// AppendBytes appends v to b as a length-prefixed bytes value.
434			func AppendBytes(b []byte, v []byte) []byte {
435			return append(AppendVarint(b, uint64(len(v))), v...)
436			}
437
438			// ConsumeBytes parses b as a length-prefixed bytes value, reporting its length.
439			// This returns a negative length upon an error (see ParseError).
440			func ConsumeBytes(b []byte) (v []byte, n int) {
441			m, n := ConsumeVarint(b)
442			if n < 0 {
443			return nil, n // forward error code
444			}
445			if m > uint64(len(b[n:])) {
446			return nil, errCodeTruncated
447			}
448			return b[n:][:m], n + int(m)
449			}
450
451			// SizeBytes returns the encoded size of a length-prefixed bytes value,
452			// given only the length.
453			func SizeBytes(n int) int {
454			return SizeVarint(uint64(n)) + n
455			}
456
457			// AppendString appends v to b as a length-prefixed bytes value.
458			func AppendString(b []byte, v string) []byte {
459			return append(AppendVarint(b, uint64(len(v))), v...)
460			}
461
462			// ConsumeString parses b as a length-prefixed bytes value, reporting its length.
463			// This returns a negative length upon an error (see ParseError).
464			func ConsumeString(b []byte) (v string, n int) {
465			bb, n := ConsumeBytes(b)
466			return string(bb), n
467			}
468
469			// AppendGroup appends v to b as group value, with a trailing end group marker.
470			// The value v must not contain the end marker.
471			func AppendGroup(b []byte, num Number, v []byte) []byte {
472			return AppendVarint(append(b, v...), EncodeTag(num, EndGroupType))
473			}
474
475			// ConsumeGroup parses b as a group value until the trailing end group marker,
476			// and verifies that the end marker matches the provided num. The value v
477			// does not contain the end marker, while the length does contain the end marker.
478			// This returns a negative length upon an error (see ParseError).
479			func ConsumeGroup(num Number, b []byte) (v []byte, n int) {
480			n = ConsumeFieldValue(num, StartGroupType, b)
481			if n < 0 {
482			return nil, n // forward error code
483			}
484			b = b[:n]
485
486			// Truncate off end group marker, but need to handle denormalized varints.
487			// Assuming end marker is never 0 (which is always the case since
488			// EndGroupType is non-zero), we can truncate all trailing bytes where the
489			// lower 7 bits are all zero (implying that the varint is denormalized).
490			for len(b) > 0 && b[len(b)-1]&0x7f == 0 {
491			b = b[:len(b)-1]
492			}
493			b = b[:len(b)-SizeTag(num)]
494			return b, n
495			}
496
497			// SizeGroup returns the encoded size of a group, given only the length.
498			func SizeGroup(num Number, n int) int {
499			return n + SizeTag(num)
500			}
501
502			// DecodeTag decodes the field Number and wire Type from its unified form.
503			// The Number is -1 if the decoded field number overflows int32.
504			// Other than overflow, this does not check for field number validity.
505			func DecodeTag(x uint64) (Number, Type) {
506			// NOTE: MessageSet allows for larger field numbers than normal.
507			if x>>3 > uint64(math.MaxInt32) {
508			return -1, 0
509			}
510			return Number(x >> 3), Type(x & 7)
511			}
512
513			// EncodeTag encodes the field Number and wire Type into its unified form.
514			func EncodeTag(num Number, typ Type) uint64 {
515			return uint64(num)<<3 \| uint64(typ&7)
516			}
517
518			// DecodeZigZag decodes a zig-zag-encoded uint64 as an int64.
519			// Input: {…, 5, 3, 1, 0, 2, 4, 6, …}
520			// Output: {…, -3, -2, -1, 0, +1, +2, +3, …}
521			func DecodeZigZag(x uint64) int64 {
522			return int64(x>>1) ^ int64(x)<<63>>63
523			}
524
525			// EncodeZigZag encodes an int64 as a zig-zag-encoded uint64.
526			// Input: {…, -3, -2, -1, 0, +1, +2, +3, …}
527			// Output: {…, 5, 3, 1, 0, 2, 4, 6, …}
528			func EncodeZigZag(x int64) uint64 {
529			return uint64(x<<1) ^ uint64(x>>63)
530			}
531
532			// DecodeBool decodes a uint64 as a bool.
533			// Input: { 0, 1, 2, …}
534			// Output: {false, true, true, …}
535			func DecodeBool(x uint64) bool {
536			return x != 0
537			}
538
539			// EncodeBool encodes a bool as a uint64.
540			// Input: {false, true}
541			// Output: { 0, 1}
542			func EncodeBool(x bool) uint64 {
543			if x {
544			return 1
545			}
546			return 0
547			}
548

cdleo / go-sqldb

Branch — main (436074)

protowire.ConsumeVarint F

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