817 lines
16 KiB
Go
817 lines
16 KiB
Go
// Copyright (c) 2012-2020 Ugorji Nwoke. All rights reserved.
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// Use of this source code is governed by a MIT license found in the LICENSE file.
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package codec
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import "io"
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// decReader abstracts the reading source, allowing implementations that can
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// read from an io.Reader or directly off a byte slice with zero-copying.
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type decReader interface {
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// readx will use the implementation scratch buffer if possible i.e. n < len(scratchbuf), OR
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// just return a view of the []byte being decoded from.
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readx(n uint) []byte
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readb([]byte)
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readn1() byte
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readn2() [2]byte
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// readn3 will read 3 bytes into the top-most elements of a 4-byte array
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readn3() [4]byte
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readn4() [4]byte
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readn8() [8]byte
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// readn1eof() (v uint8, eof bool)
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// // read up to 8 bytes at a time
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// readn(num uint8) (v [8]byte)
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numread() uint // number of bytes read
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// skip any whitespace characters, and return the first non-matching byte
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skipWhitespace() (token byte)
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// jsonReadNum will include last read byte in first element of slice,
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// and continue numeric characters until it sees a non-numeric char
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// or EOF. If it sees a non-numeric character, it will unread that.
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jsonReadNum() []byte
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// jsonReadAsisChars will read json plain characters (anything but " or \)
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// and return a slice terminated by a non-json asis character.
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jsonReadAsisChars() []byte
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// skip will skip any byte that matches, and return the first non-matching byte
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// skip(accept *bitset256) (token byte)
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// readTo will read any byte that matches, stopping once no-longer matching.
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// readTo(accept *bitset256) (out []byte)
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// readUntil will read, only stopping once it matches the 'stop' byte (which it excludes).
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readUntil(stop byte) (out []byte)
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}
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// ------------------------------------------------
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type unreadByteStatus uint8
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// unreadByteStatus goes from
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// undefined (when initialized) -- (read) --> canUnread -- (unread) --> canRead ...
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const (
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unreadByteUndefined unreadByteStatus = iota
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unreadByteCanRead
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unreadByteCanUnread
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)
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// --------------------
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type ioDecReaderCommon struct {
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r io.Reader // the reader passed in
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n uint // num read
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l byte // last byte
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ls unreadByteStatus // last byte status
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b [6]byte // tiny buffer for reading single bytes
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blist *bytesFreelist
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bufr []byte // buffer for readTo/readUntil
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}
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func (z *ioDecReaderCommon) reset(r io.Reader, blist *bytesFreelist) {
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z.blist = blist
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z.r = r
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z.ls = unreadByteUndefined
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z.l, z.n = 0, 0
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z.bufr = z.blist.check(z.bufr, 256)
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}
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func (z *ioDecReaderCommon) numread() uint {
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return z.n
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}
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// ------------------------------------------
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// ioDecReader is a decReader that reads off an io.Reader.
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//
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// It also has a fallback implementation of ByteScanner if needed.
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type ioDecReader struct {
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ioDecReaderCommon
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br io.ByteScanner
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x [64 + 48]byte // for: get struct field name, swallow valueTypeBytes, etc
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}
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func (z *ioDecReader) reset(r io.Reader, blist *bytesFreelist) {
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z.ioDecReaderCommon.reset(r, blist)
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z.br, _ = r.(io.ByteScanner)
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}
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func (z *ioDecReader) Read(p []byte) (n int, err error) {
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if len(p) == 0 {
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return
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}
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var firstByte bool
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if z.ls == unreadByteCanRead {
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z.ls = unreadByteCanUnread
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p[0] = z.l
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if len(p) == 1 {
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n = 1
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return
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}
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firstByte = true
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p = p[1:]
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}
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n, err = z.r.Read(p)
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if n > 0 {
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if err == io.EOF && n == len(p) {
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err = nil // read was successful, so postpone EOF (till next time)
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}
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z.l = p[n-1]
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z.ls = unreadByteCanUnread
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}
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if firstByte {
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n++
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}
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return
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}
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func (z *ioDecReader) ReadByte() (c byte, err error) {
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if z.br != nil {
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c, err = z.br.ReadByte()
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if err == nil {
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z.l = c
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z.ls = unreadByteCanUnread
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}
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return
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}
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n, err := z.Read(z.b[:1])
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if n == 1 {
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c = z.b[0]
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if err == io.EOF {
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err = nil // read was successful, so postpone EOF (till next time)
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}
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}
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return
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}
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func (z *ioDecReader) UnreadByte() (err error) {
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if z.br != nil {
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err = z.br.UnreadByte()
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if err == nil {
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z.ls = unreadByteCanRead
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}
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return
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}
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switch z.ls {
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case unreadByteCanUnread:
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z.ls = unreadByteCanRead
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case unreadByteCanRead:
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err = errDecUnreadByteLastByteNotRead
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case unreadByteUndefined:
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err = errDecUnreadByteNothingToRead
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default:
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err = errDecUnreadByteUnknown
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}
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return
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}
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func (z *ioDecReader) readn2() (bs [2]byte) {
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z.readb(bs[:])
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return
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}
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func (z *ioDecReader) readn3() (bs [4]byte) {
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z.readb(bs[1:])
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return
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}
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func (z *ioDecReader) readn4() (bs [4]byte) {
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z.readb(bs[:])
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return
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}
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func (z *ioDecReader) readn8() (bs [8]byte) {
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z.readb(bs[:])
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return
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}
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func (z *ioDecReader) readx(n uint) (bs []byte) {
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if n == 0 {
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return
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}
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if n < uint(len(z.x)) {
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bs = z.x[:n]
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} else {
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bs = make([]byte, n)
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}
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_, err := readFull(z.r, bs)
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halt.onerror(err)
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z.n += uint(len(bs))
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return
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}
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func (z *ioDecReader) readb(bs []byte) {
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if len(bs) == 0 {
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return
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}
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_, err := readFull(z.r, bs)
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halt.onerror(err)
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z.n += uint(len(bs))
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}
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func (z *ioDecReader) readn1() (b uint8) {
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b, err := z.ReadByte()
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halt.onerror(err)
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z.n++
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return
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}
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func (z *ioDecReader) readn1eof() (b uint8, eof bool) {
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b, err := z.ReadByte()
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if err == nil {
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z.n++
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} else if err == io.EOF {
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eof = true
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} else {
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halt.onerror(err)
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}
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return
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}
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func (z *ioDecReader) jsonReadNum() (bs []byte) {
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z.unreadn1()
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z.bufr = z.bufr[:0]
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LOOP:
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i, eof := z.readn1eof()
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if eof {
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return z.bufr
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}
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if isNumberChar(i) {
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z.bufr = append(z.bufr, i)
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goto LOOP
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}
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z.unreadn1()
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return z.bufr
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}
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func (z *ioDecReader) jsonReadAsisChars() (bs []byte) {
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z.bufr = z.bufr[:0]
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LOOP:
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i := z.readn1()
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z.bufr = append(z.bufr, i)
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if i == '"' || i == '\\' {
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return z.bufr
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}
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goto LOOP
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}
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func (z *ioDecReader) skipWhitespace() (token byte) {
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LOOP:
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token = z.readn1()
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if isWhitespaceChar(token) {
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goto LOOP
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}
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return
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}
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func (z *ioDecReader) readUntil(stop byte) []byte {
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z.bufr = z.bufr[:0]
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LOOP:
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token := z.readn1()
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z.bufr = append(z.bufr, token)
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if token == stop {
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return z.bufr[:len(z.bufr)-1]
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}
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goto LOOP
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}
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func (z *ioDecReader) unreadn1() {
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err := z.UnreadByte()
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halt.onerror(err)
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z.n--
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}
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// ------------------------------------
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type bufioDecReader struct {
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ioDecReaderCommon
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c uint // cursor
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buf []byte
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}
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func (z *bufioDecReader) reset(r io.Reader, bufsize int, blist *bytesFreelist) {
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z.ioDecReaderCommon.reset(r, blist)
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z.c = 0
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if cap(z.buf) < bufsize {
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z.buf = blist.get(bufsize)
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} else {
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z.buf = z.buf[:0]
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}
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}
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func (z *bufioDecReader) readb(p []byte) {
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var n = uint(copy(p, z.buf[z.c:]))
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z.n += n
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z.c += n
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if len(p) != int(n) {
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z.readbFill(p, n, true, false)
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}
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}
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func readbFillHandleErr(err error, must, eof bool) (isEOF bool) {
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if err == io.EOF {
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isEOF = true
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}
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if must && !(eof && isEOF) {
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halt.onerror(err)
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}
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return
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}
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func (z *bufioDecReader) readbFill(p0 []byte, n uint, must, eof bool) (isEOF bool, err error) {
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// at this point, there's nothing in z.buf to read (z.buf is fully consumed)
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var p []byte
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if p0 != nil {
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p = p0[n:]
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}
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var n2 uint
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if len(p) > cap(z.buf) {
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n2, err = readFull(z.r, p)
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if err != nil {
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isEOF = readbFillHandleErr(err, must, eof)
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return
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}
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n += n2
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z.n += n2
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// always keep last byte in z.buf
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z.buf = z.buf[:1]
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z.buf[0] = p[len(p)-1]
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z.c = 1
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return
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}
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// z.c is now 0, and len(p) <= cap(z.buf)
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var n1 int
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LOOP:
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// for len(p) > 0 && z.err == nil {
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z.buf = z.buf[0:cap(z.buf)]
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n1, err = z.r.Read(z.buf)
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n2 = uint(n1)
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if n2 == 0 && err != nil {
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isEOF = readbFillHandleErr(err, must, eof)
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return
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}
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err = nil
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z.buf = z.buf[:n2]
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z.c = 0
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if len(p) > 0 {
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n2 = uint(copy(p, z.buf))
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z.c = n2
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n += n2
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z.n += n2
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p = p[n2:]
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if len(p) > 0 {
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goto LOOP
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}
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if z.c == 0 {
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z.buf = z.buf[:1]
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z.buf[0] = p[len(p)-1]
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z.c = 1
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}
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}
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return
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}
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func (z *bufioDecReader) readn1() (b byte) {
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if z.c >= uint(len(z.buf)) {
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z.readbFill(nil, 0, true, false)
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}
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b = z.buf[z.c]
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z.c++
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z.n++
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return
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}
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func (z *bufioDecReader) readn1eof() (b byte, eof bool) {
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if z.c >= uint(len(z.buf)) {
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eof, _ = z.readbFill(nil, 0, true, true)
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if eof {
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return
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}
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}
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b = z.buf[z.c]
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z.c++
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z.n++
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return
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}
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func (z *bufioDecReader) unreadn1() {
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if z.c == 0 {
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halt.onerror(errDecUnreadByteNothingToRead)
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}
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z.c--
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z.n--
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}
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func (z *bufioDecReader) readn2() (bs [2]byte) {
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z.readb(bs[:])
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return
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}
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func (z *bufioDecReader) readn3() (bs [4]byte) {
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z.readb(bs[1:])
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return
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}
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func (z *bufioDecReader) readn4() (bs [4]byte) {
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z.readb(bs[:])
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return
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}
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func (z *bufioDecReader) readn8() (bs [8]byte) {
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z.readb(bs[:])
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return
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}
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func (z *bufioDecReader) readx(n uint) (bs []byte) {
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if n == 0 {
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// return
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} else if z.c+n <= uint(len(z.buf)) {
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bs = z.buf[z.c : z.c+n]
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z.n += n
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z.c += n
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} else {
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bs = make([]byte, n)
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// n no longer used - can reuse
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n = uint(copy(bs, z.buf[z.c:]))
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z.n += n
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z.c += n
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z.readbFill(bs, n, true, false)
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}
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return
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}
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func (z *bufioDecReader) jsonReadNum() (bs []byte) {
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z.unreadn1()
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z.bufr = z.bufr[:0]
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LOOP:
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i, eof := z.readn1eof()
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if eof {
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return z.bufr
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}
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if isNumberChar(i) {
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z.bufr = append(z.bufr, i)
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goto LOOP
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}
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z.unreadn1()
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return z.bufr
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}
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func (z *bufioDecReader) jsonReadAsisChars() (bs []byte) {
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z.bufr = z.bufr[:0]
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LOOP:
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i := z.readn1()
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z.bufr = append(z.bufr, i)
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if i == '"' || i == '\\' {
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return z.bufr
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}
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goto LOOP
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}
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func (z *bufioDecReader) skipWhitespace() (token byte) {
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i := z.c
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LOOP:
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if i < uint(len(z.buf)) {
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// inline z.skipLoopFn(i) and refactor, so cost is within inline budget
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token = z.buf[i]
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i++
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if isWhitespaceChar(token) {
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goto LOOP
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}
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z.n += i - 2 - z.c
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z.c = i
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return
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}
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return z.skipFillWhitespace()
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}
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func (z *bufioDecReader) skipFillWhitespace() (token byte) {
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z.n += uint(len(z.buf)) - z.c
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var i, n2 int
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var err error
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for {
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z.c = 0
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z.buf = z.buf[0:cap(z.buf)]
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n2, err = z.r.Read(z.buf)
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if n2 == 0 {
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halt.onerror(err)
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}
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z.buf = z.buf[:n2]
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for i, token = range z.buf {
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if !isWhitespaceChar(token) {
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z.n += (uint(i) - z.c) - 1
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z.loopFn(uint(i + 1))
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return
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}
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}
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z.n += uint(n2)
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}
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}
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func (z *bufioDecReader) loopFn(i uint) {
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z.c = i
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}
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func (z *bufioDecReader) readUntil(stop byte) (out []byte) {
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i := z.c
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LOOP:
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if i < uint(len(z.buf)) {
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if z.buf[i] == stop {
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z.n += (i - z.c) - 1
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i++
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out = z.buf[z.c:i]
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z.c = i
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goto FINISH
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}
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i++
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goto LOOP
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}
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out = z.readUntilFill(stop)
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FINISH:
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return out[:len(out)-1]
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}
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func (z *bufioDecReader) readUntilFill(stop byte) []byte {
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z.bufr = z.bufr[:0]
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z.n += uint(len(z.buf)) - z.c
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z.bufr = append(z.bufr, z.buf[z.c:]...)
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for {
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z.c = 0
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z.buf = z.buf[0:cap(z.buf)]
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n1, err := z.r.Read(z.buf)
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if n1 == 0 {
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halt.onerror(err)
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}
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n2 := uint(n1)
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z.buf = z.buf[:n2]
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for i, token := range z.buf {
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if token == stop {
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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)
|