gotosocial/vendor/github.com/ugorji/go/codec/reader.go
Tobi Smethurst 98263a7de6
Grand test fixup (#138)
* start fixing up tests

* fix up tests + automate with drone

* fiddle with linting

* messing about with drone.yml

* some more fiddling

* hmmm

* add cache

* add vendor directory

* verbose

* ci updates

* update some little things

* update sig
2021-08-12 21:03:24 +02:00

816 lines
16 KiB
Go

// Copyright (c) 2012-2020 Ugorji Nwoke. All rights reserved.
// Use of this source code is governed by a MIT license found in the LICENSE file.
package codec
import "io"
// decReader abstracts the reading source, allowing implementations that can
// read from an io.Reader or directly off a byte slice with zero-copying.
type decReader interface {
// readx will use the implementation scratch buffer if possible i.e. n < len(scratchbuf), OR
// just return a view of the []byte being decoded from.
readx(n uint) []byte
readb([]byte)
readn1() byte
readn2() [2]byte
// readn3 will read 3 bytes into the top-most elements of a 4-byte array
readn3() [4]byte
readn4() [4]byte
readn8() [8]byte
// readn1eof() (v uint8, eof bool)
// // read up to 8 bytes at a time
// readn(num uint8) (v [8]byte)
numread() uint // number of bytes read
// skip any whitespace characters, and return the first non-matching byte
skipWhitespace() (token byte)
// jsonReadNum will include last read byte in first element of slice,
// and continue numeric characters until it sees a non-numeric char
// or EOF. If it sees a non-numeric character, it will unread that.
jsonReadNum() []byte
// jsonReadAsisChars will read json plain characters (anything but " or \)
// and return a slice terminated by a non-json asis character.
jsonReadAsisChars() []byte
// skip will skip any byte that matches, and return the first non-matching byte
// skip(accept *bitset256) (token byte)
// readTo will read any byte that matches, stopping once no-longer matching.
// readTo(accept *bitset256) (out []byte)
// readUntil will read, only stopping once it matches the 'stop' byte (which it excludes).
readUntil(stop byte) (out []byte)
}
// ------------------------------------------------
type unreadByteStatus uint8
// unreadByteStatus goes from
// undefined (when initialized) -- (read) --> canUnread -- (unread) --> canRead ...
const (
unreadByteUndefined unreadByteStatus = iota
unreadByteCanRead
unreadByteCanUnread
)
// --------------------
type ioDecReaderCommon struct {
r io.Reader // the reader passed in
n uint // num read
l byte // last byte
ls unreadByteStatus // last byte status
b [6]byte // tiny buffer for reading single bytes
blist *bytesFreelist
bufr []byte // buffer for readTo/readUntil
}
func (z *ioDecReaderCommon) reset(r io.Reader, blist *bytesFreelist) {
z.blist = blist
z.r = r
z.ls = unreadByteUndefined
z.l, z.n = 0, 0
z.bufr = z.blist.check(z.bufr, 256)
}
func (z *ioDecReaderCommon) numread() uint {
return z.n
}
// ------------------------------------------
// ioDecReader is a decReader that reads off an io.Reader.
//
// It also has a fallback implementation of ByteScanner if needed.
type ioDecReader struct {
ioDecReaderCommon
br io.ByteScanner
x [64 + 48]byte // for: get struct field name, swallow valueTypeBytes, etc
}
func (z *ioDecReader) reset(r io.Reader, blist *bytesFreelist) {
z.ioDecReaderCommon.reset(r, blist)
z.br, _ = r.(io.ByteScanner)
}
func (z *ioDecReader) Read(p []byte) (n int, err error) {
if len(p) == 0 {
return
}
var firstByte bool
if z.ls == unreadByteCanRead {
z.ls = unreadByteCanUnread
p[0] = z.l
if len(p) == 1 {
n = 1
return
}
firstByte = true
p = p[1:]
}
n, err = z.r.Read(p)
if n > 0 {
if err == io.EOF && n == len(p) {
err = nil // read was successful, so postpone EOF (till next time)
}
z.l = p[n-1]
z.ls = unreadByteCanUnread
}
if firstByte {
n++
}
return
}
func (z *ioDecReader) ReadByte() (c byte, err error) {
if z.br != nil {
c, err = z.br.ReadByte()
if err == nil {
z.l = c
z.ls = unreadByteCanUnread
}
return
}
n, err := z.Read(z.b[:1])
if n == 1 {
c = z.b[0]
if err == io.EOF {
err = nil // read was successful, so postpone EOF (till next time)
}
}
return
}
func (z *ioDecReader) UnreadByte() (err error) {
if z.br != nil {
err = z.br.UnreadByte()
if err == nil {
z.ls = unreadByteCanRead
}
return
}
switch z.ls {
case unreadByteCanUnread:
z.ls = unreadByteCanRead
case unreadByteCanRead:
err = errDecUnreadByteLastByteNotRead
case unreadByteUndefined:
err = errDecUnreadByteNothingToRead
default:
err = errDecUnreadByteUnknown
}
return
}
func (z *ioDecReader) readn2() (bs [2]byte) {
z.readb(bs[:])
return
}
func (z *ioDecReader) readn3() (bs [4]byte) {
z.readb(bs[1:])
return
}
func (z *ioDecReader) readn4() (bs [4]byte) {
z.readb(bs[:])
return
}
func (z *ioDecReader) readn8() (bs [8]byte) {
z.readb(bs[:])
return
}
func (z *ioDecReader) readx(n uint) (bs []byte) {
if n == 0 {
return
}
if n < uint(len(z.x)) {
bs = z.x[:n]
} else {
bs = make([]byte, n)
}
_, err := readFull(z.r, bs)
halt.onerror(err)
z.n += uint(len(bs))
return
}
func (z *ioDecReader) readb(bs []byte) {
if len(bs) == 0 {
return
}
_, err := readFull(z.r, bs)
halt.onerror(err)
z.n += uint(len(bs))
}
func (z *ioDecReader) readn1() (b uint8) {
b, err := z.ReadByte()
halt.onerror(err)
z.n++
return
}
func (z *ioDecReader) readn1eof() (b uint8, eof bool) {
b, err := z.ReadByte()
if err == nil {
z.n++
} else if err == io.EOF {
eof = true
} else {
halt.onerror(err)
}
return
}
func (z *ioDecReader) jsonReadNum() (bs []byte) {
z.unreadn1()
z.bufr = z.bufr[:0]
LOOP:
i, eof := z.readn1eof()
if eof {
return z.bufr
}
if isNumberChar(i) {
z.bufr = append(z.bufr, i)
goto LOOP
}
z.unreadn1()
return z.bufr
}
func (z *ioDecReader) jsonReadAsisChars() (bs []byte) {
z.bufr = z.bufr[:0]
LOOP:
i := z.readn1()
z.bufr = append(z.bufr, i)
if i == '"' || i == '\\' {
return z.bufr
}
goto LOOP
}
func (z *ioDecReader) skipWhitespace() (token byte) {
LOOP:
token = z.readn1()
if isWhitespaceChar(token) {
goto LOOP
}
return
}
func (z *ioDecReader) readUntil(stop byte) []byte {
z.bufr = z.bufr[:0]
LOOP:
token := z.readn1()
z.bufr = append(z.bufr, token)
if token == stop {
return z.bufr[:len(z.bufr)-1]
}
goto LOOP
}
func (z *ioDecReader) unreadn1() {
err := z.UnreadByte()
halt.onerror(err)
z.n--
}
// ------------------------------------
type bufioDecReader struct {
ioDecReaderCommon
c uint // cursor
buf []byte
}
func (z *bufioDecReader) reset(r io.Reader, bufsize int, blist *bytesFreelist) {
z.ioDecReaderCommon.reset(r, blist)
z.c = 0
if cap(z.buf) < bufsize {
z.buf = blist.get(bufsize)
} else {
z.buf = z.buf[:0]
}
}
func (z *bufioDecReader) readb(p []byte) {
var n = uint(copy(p, z.buf[z.c:]))
z.n += n
z.c += n
if len(p) != int(n) {
z.readbFill(p, n, true, false)
}
}
func readbFillHandleErr(err error, must, eof bool) (isEOF bool) {
if err == io.EOF {
isEOF = true
}
if must && !(eof && isEOF) {
halt.onerror(err)
}
return
}
func (z *bufioDecReader) readbFill(p0 []byte, n uint, must, eof bool) (isEOF bool, err error) {
// at this point, there's nothing in z.buf to read (z.buf is fully consumed)
var p []byte
if p0 != nil {
p = p0[n:]
}
var n2 uint
if len(p) > cap(z.buf) {
n2, err = readFull(z.r, p)
if err != nil {
isEOF = readbFillHandleErr(err, must, eof)
return
}
n += n2
z.n += n2
// always keep last byte in z.buf
z.buf = z.buf[:1]
z.buf[0] = p[len(p)-1]
z.c = 1
return
}
// z.c is now 0, and len(p) <= cap(z.buf)
var n1 int
LOOP:
// for len(p) > 0 && z.err == nil {
z.buf = z.buf[0:cap(z.buf)]
n1, err = z.r.Read(z.buf)
n2 = uint(n1)
if n2 == 0 && err != nil {
isEOF = readbFillHandleErr(err, must, eof)
return
}
err = nil
z.buf = z.buf[:n2]
z.c = 0
if len(p) > 0 {
n2 = uint(copy(p, z.buf))
z.c = n2
n += n2
z.n += n2
p = p[n2:]
if len(p) > 0 {
goto LOOP
}
if z.c == 0 {
z.buf = z.buf[:1]
z.buf[0] = p[len(p)-1]
z.c = 1
}
}
return
}
func (z *bufioDecReader) readn1() (b byte) {
if z.c >= uint(len(z.buf)) {
z.readbFill(nil, 0, true, false)
}
b = z.buf[z.c]
z.c++
z.n++
return
}
func (z *bufioDecReader) readn1eof() (b byte, eof bool) {
if z.c >= uint(len(z.buf)) {
eof, _ = z.readbFill(nil, 0, true, true)
if eof {
return
}
}
b = z.buf[z.c]
z.c++
z.n++
return
}
func (z *bufioDecReader) unreadn1() {
if z.c == 0 {
halt.onerror(errDecUnreadByteNothingToRead)
}
z.c--
z.n--
}
func (z *bufioDecReader) readn2() (bs [2]byte) {
z.readb(bs[:])
return
}
func (z *bufioDecReader) readn3() (bs [4]byte) {
z.readb(bs[1:])
return
}
func (z *bufioDecReader) readn4() (bs [4]byte) {
z.readb(bs[:])
return
}
func (z *bufioDecReader) readn8() (bs [8]byte) {
z.readb(bs[:])
return
}
func (z *bufioDecReader) readx(n uint) (bs []byte) {
if n == 0 {
// return
} else if z.c+n <= uint(len(z.buf)) {
bs = z.buf[z.c : z.c+n]
z.n += n
z.c += n
} else {
bs = make([]byte, n)
// n no longer used - can reuse
n = uint(copy(bs, z.buf[z.c:]))
z.n += n
z.c += n
z.readbFill(bs, n, true, false)
}
return
}
func (z *bufioDecReader) jsonReadNum() (bs []byte) {
z.unreadn1()
z.bufr = z.bufr[:0]
LOOP:
i, eof := z.readn1eof()
if eof {
return z.bufr
}
if isNumberChar(i) {
z.bufr = append(z.bufr, i)
goto LOOP
}
z.unreadn1()
return z.bufr
}
func (z *bufioDecReader) jsonReadAsisChars() (bs []byte) {
z.bufr = z.bufr[:0]
LOOP:
i := z.readn1()
z.bufr = append(z.bufr, i)
if i == '"' || i == '\\' {
return z.bufr
}
goto LOOP
}
func (z *bufioDecReader) skipWhitespace() (token byte) {
i := z.c
LOOP:
if i < uint(len(z.buf)) {
// inline z.skipLoopFn(i) and refactor, so cost is within inline budget
token = z.buf[i]
i++
if isWhitespaceChar(token) {
goto LOOP
}
z.n += i - 2 - z.c
z.c = i
return
}
return z.skipFillWhitespace()
}
func (z *bufioDecReader) skipFillWhitespace() (token byte) {
z.n += uint(len(z.buf)) - z.c
var i, n2 int
var err error
for {
z.c = 0
z.buf = z.buf[0:cap(z.buf)]
n2, err = z.r.Read(z.buf)
if n2 == 0 {
halt.onerror(err)
}
z.buf = z.buf[:n2]
for i, token = range z.buf {
if !isWhitespaceChar(token) {
z.n += (uint(i) - z.c) - 1
z.loopFn(uint(i + 1))
return
}
}
z.n += uint(n2)
}
}
func (z *bufioDecReader) loopFn(i uint) {
z.c = i
}
func (z *bufioDecReader) readUntil(stop byte) (out []byte) {
i := z.c
LOOP:
if i < uint(len(z.buf)) {
if z.buf[i] == stop {
z.n += (i - z.c) - 1
i++
out = z.buf[z.c:i]
z.c = i
goto FINISH
}
i++
goto LOOP
}
out = z.readUntilFill(stop)
FINISH:
return out[:len(out)-1]
}
func (z *bufioDecReader) readUntilFill(stop byte) []byte {
z.bufr = z.bufr[:0]
z.n += uint(len(z.buf)) - z.c
z.bufr = append(z.bufr, z.buf[z.c:]...)
for {
z.c = 0
z.buf = z.buf[0:cap(z.buf)]
n1, err := z.r.Read(z.buf)
if n1 == 0 {
halt.onerror(err)
}
n2 := uint(n1)
z.buf = z.buf[:n2]
for i, token := range z.buf {
if token == stop {
z.n += (uint(i) - z.c) - 1
z.bufr = append(z.bufr, z.buf[z.c:i+1]...)
z.loopFn(uint(i + 1))
return z.bufr
}
}
z.bufr = append(z.bufr, z.buf...)
z.n += n2
}
}
// ------------------------------------
// bytesDecReader is a decReader that reads off a byte slice with zero copying
//
// Note: we do not try to convert index'ing out of bounds to an io.EOF.
// instead, we let it bubble up to the exported Encode/Decode method
// and recover it as an io.EOF.
//
// see panicValToErr(...) function in helper.go.
type bytesDecReader struct {
b []byte // data
c uint // cursor
}
func (z *bytesDecReader) reset(in []byte) {
z.b = in[:len(in):len(in)] // reslicing must not go past capacity
z.c = 0
}
func (z *bytesDecReader) numread() uint {
return z.c
}
// Note: slicing from a non-constant start position is more expensive,
// as more computation is required to decipher the pointer start position.
// However, we do it only once, and it's better than reslicing both z.b and return value.
func (z *bytesDecReader) readx(n uint) (bs []byte) {
x := z.c + n
bs = z.b[z.c:x]
z.c = x
return
}
func (z *bytesDecReader) readb(bs []byte) {
copy(bs, z.readx(uint(len(bs))))
}
// MARKER: do not use this - as it calls into memmove (as the size of data to move is unknown)
// func (z *bytesDecReader) readnn(bs []byte, n uint) {
// x := z.c
// copy(bs, z.b[x:x+n])
// z.c += n
// }
// func (z *bytesDecReader) readn(num uint8) (bs [8]byte) {
// x := z.c + uint(num)
// copy(bs[:], z.b[z.c:x]) // slice z.b completely, so we get bounds error if past
// z.c = x
// return
// }
// func (z *bytesDecReader) readn1() uint8 {
// z.c++
// return z.b[z.c-1]
// }
func (z *bytesDecReader) readn1() (v uint8) {
v = z.b[z.c]
z.c++
return
}
// MARKER: for readn{2,3,4,8}, ensure you slice z.b completely so we get bounds error if past end.
func (z *bytesDecReader) readn2() (bs [2]byte) {
// copy(bs[:], z.b[z.c:z.c+2])
bs[1] = z.b[z.c+1]
bs[0] = z.b[z.c]
z.c += 2
return
}
func (z *bytesDecReader) readn3() (bs [4]byte) {
// copy(bs[1:], z.b[z.c:z.c+3])
bs = okBytes3(z.b[z.c : z.c+3])
z.c += 3
return
}
func (z *bytesDecReader) readn4() (bs [4]byte) {
// copy(bs[:], z.b[z.c:z.c+4])
bs = okBytes4(z.b[z.c : z.c+4])
z.c += 4
return
}
func (z *bytesDecReader) readn8() (bs [8]byte) {
// copy(bs[:], z.b[z.c:z.c+8])
bs = okBytes8(z.b[z.c : z.c+8])
z.c += 8
return
}
func (z *bytesDecReader) jsonReadNum() []byte {
z.c--
i := z.c
LOOP:
if i < uint(len(z.b)) && isNumberChar(z.b[i]) {
i++
goto LOOP
}
z.c, i = i, z.c
return z.b[i:z.c]
}
func (z *bytesDecReader) jsonReadAsisChars() []byte {
i := z.c
LOOP:
token := z.b[i]
i++
if token == '"' || token == '\\' {
z.c, i = i, z.c
return z.b[i:z.c]
}
goto LOOP
}
func (z *bytesDecReader) skipWhitespace() (token byte) {
i := z.c
LOOP:
token = z.b[i]
if isWhitespaceChar(token) {
i++
goto LOOP
}
z.c = i + 1
return
}
func (z *bytesDecReader) readUntil(stop byte) (out []byte) {
i := z.c
LOOP:
if z.b[i] == stop {
out = z.b[z.c:i]
z.c = i + 1
return
}
i++
goto LOOP
}
// --------------
type decRd struct {
mtr bool // is maptype a known type?
str bool // is slicetype a known type?
be bool // is binary encoding
js bool // is json handle
jsms bool // is json handle, and MapKeyAsString
cbor bool // is cbor handle
bytes bool // is bytes reader
bufio bool // is this a bufioDecReader?
rb bytesDecReader
ri *ioDecReader
bi *bufioDecReader
decReader
}
// From out benchmarking, we see the following in terms of performance:
//
// - interface calls
// - branch that can inline what it calls
//
// the if/else-if/else block is expensive to inline.
// Each node of this construct costs a lot and dominates the budget.
// Best to only do an if fast-path else block (so fast-path is inlined).
// This is irrespective of inlineExtraCallCost set in $GOROOT/src/cmd/compile/internal/gc/inl.go
//
// In decRd methods below, we delegate all IO functions into their own methods.
// This allows for the inlining of the common path when z.bytes=true.
// Go 1.12+ supports inlining methods with up to 1 inlined function (or 2 if no other constructs).
//
// However, up through Go 1.13, decRd's readXXX, skip and unreadXXX methods are not inlined.
// Consequently, there is no benefit to do the xxxIO methods for decRd at this time.
// Instead, we have a if/else-if/else block so that IO calls do not have to jump through
// a second unnecessary function call.
//
// If golang inlining gets better and bytesDecReader methods can be inlined,
// then we can revert to using these 2 functions so the bytesDecReader
// methods are inlined and the IO paths call out to a function.
//
// decRd is designed to embed a decReader, and then re-implement some of the decReader
// methods using a conditional branch. We only override the ones that have a bytes version
// that is small enough to be inlined. We use ./run.sh -z to check.
// Right now, only numread and readn1 can be inlined.
func (z *decRd) numread() uint {
if z.bytes {
return z.rb.numread()
} else if z.bufio {
return z.bi.numread()
} else {
return z.ri.numread()
}
}
func (z *decRd) readn1() (v uint8) {
if z.bytes {
// MARKER: manually inline, else this function is not inlined.
// Keep in sync with bytesDecReader.readn1
// return z.rb.readn1()
v = z.rb.b[z.rb.c]
z.rb.c++
} else {
v = z.readn1IO()
}
return
}
func (z *decRd) readn1IO() uint8 {
if z.bufio {
return z.bi.readn1()
}
return z.ri.readn1()
}
type devNullReader struct{}
func (devNullReader) Read(p []byte) (int, error) { return 0, io.EOF }
func (devNullReader) Close() error { return nil }
func readFull(r io.Reader, bs []byte) (n uint, err error) {
var nn int
for n < uint(len(bs)) && err == nil {
nn, err = r.Read(bs[n:])
if nn > 0 {
if err == io.EOF {
// leave EOF for next time
err = nil
}
n += uint(nn)
}
}
// do not do this below - it serves no purpose
// if n != len(bs) && err == io.EOF { err = io.ErrUnexpectedEOF }
return
}
var _ decReader = (*decRd)(nil)