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// 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"
)
const maxConsecutiveEmptyWrites = 16 // 2 is sufficient, 16 is enough, 64 is optimal
// encWriter abstracts writing to a byte array or to an io.Writer.
type encWriterI interface {
writeb([]byte)
writestr(string)
writeqstr(string) // write string wrapped in quotes ie "..."
writen1(byte)
// add convenience functions for writing 2,4
writen2(byte, byte)
writen4([4]byte)
writen8([8]byte)
// isBytes() bool
end()
resetIO(w io.Writer, bufsize int, blist *bytesFreeList)
resetBytes(in []byte, out *[]byte)
}
// ---------------------------------------------
type bufioEncWriter struct {
w io.Writer
buf []byte
n int
b [16]byte // scratch buffer and padding (cache-aligned)
}
// MARKER: use setByteAt/byteAt to elide the bounds-checks
// when we are sure that we don't go beyond the bounds.
func (z *bufioEncWriter) resetBytes(in []byte, out *[]byte) {
halt.errorStr("resetBytes is unsupported by bufioEncWriter")
}
func (z *bufioEncWriter) resetIO(w io.Writer, bufsize int, blist *bytesFreeList) {
z.w = w
z.n = 0
// use minimum bufsize of 16, matching the array z.b and accomodating writen methods (where n <= 8)
bufsize = max(16, bufsize) // max(byteBufSize, bufsize)
if cap(z.buf) < bufsize {
if len(z.buf) > 0 && &z.buf[0] != &z.b[0] {
blist.put(z.buf)
}
if len(z.b) > bufsize {
z.buf = z.b[:]
} else {
z.buf = blist.get(bufsize)
}
}
z.buf = z.buf[:cap(z.buf)]
}
func (z *bufioEncWriter) flushErr() (err error) {
var n int
for i := maxConsecutiveEmptyReads; i > 0; i-- {
n, err = z.w.Write(z.buf[:z.n])
z.n -= n
if z.n == 0 || err != nil {
return
}
// at this point: z.n > 0 && err == nil
if n > 0 {
copy(z.buf, z.buf[n:z.n+n])
}
}
return io.ErrShortWrite // OR io.ErrNoProgress: not enough (or no) data written
}
func (z *bufioEncWriter) flush() {
halt.onerror(z.flushErr())
}
func (z *bufioEncWriter) writeb(s []byte) {
LOOP:
a := len(z.buf) - z.n
if len(s) > a {
z.n += copy(z.buf[z.n:], s[:a])
s = s[a:]
z.flush()
goto LOOP
}
z.n += copy(z.buf[z.n:], s)
}
func (z *bufioEncWriter) writestr(s string) {
// z.writeb(bytesView(s)) // inlined below
LOOP:
a := len(z.buf) - z.n
if len(s) > a {
z.n += copy(z.buf[z.n:], s[:a])
s = s[a:]
z.flush()
goto LOOP
}
z.n += copy(z.buf[z.n:], s)
}
func (z *bufioEncWriter) writeqstr(s string) {
// z.writen1('"')
// z.writestr(s)
// z.writen1('"')
if z.n+len(s)+2 > len(z.buf) {
z.flush()
}
setByteAt(z.buf, uint(z.n), '"')
// z.buf[z.n] = '"'
z.n++
LOOP:
a := len(z.buf) - z.n
if len(s)+1 > a {
z.n += copy(z.buf[z.n:], s[:a])
s = s[a:]
z.flush()
goto LOOP
}
z.n += copy(z.buf[z.n:], s)
setByteAt(z.buf, uint(z.n), '"')
// z.buf[z.n] = '"'
z.n++
}
func (z *bufioEncWriter) writen1(b1 byte) {
if 1 > len(z.buf)-z.n {
z.flush()
}
setByteAt(z.buf, uint(z.n), b1)
// z.buf[z.n] = b1
z.n++
}
func (z *bufioEncWriter) writen2(b1, b2 byte) {
if 2 > len(z.buf)-z.n {
z.flush()
}
setByteAt(z.buf, uint(z.n+1), b2)
setByteAt(z.buf, uint(z.n), b1)
// z.buf[z.n+1] = b2
// z.buf[z.n] = b1
z.n += 2
}
func (z *bufioEncWriter) writen4(b [4]byte) {
if 4 > len(z.buf)-z.n {
z.flush()
}
// setByteAt(z.buf, uint(z.n+3), b4)
// setByteAt(z.buf, uint(z.n+2), b3)
// setByteAt(z.buf, uint(z.n+1), b2)
// setByteAt(z.buf, uint(z.n), b1)
copy(z.buf[z.n:], b[:])
z.n += 4
}
func (z *bufioEncWriter) writen8(b [8]byte) {
if 8 > len(z.buf)-z.n {
z.flush()
}
copy(z.buf[z.n:], b[:])
z.n += 8
}
func (z *bufioEncWriter) endErr() (err error) {
if z.n > 0 {
err = z.flushErr()
}
return
}
func (z *bufioEncWriter) end() {
halt.onerror(z.endErr())
}
// ---------------------------------------------
var bytesEncAppenderDefOut = []byte{}
// bytesEncAppender implements encWriter and can write to an byte slice.
type bytesEncAppender struct {
b []byte
out *[]byte
}
func (z *bytesEncAppender) writeb(s []byte) {
z.b = append(z.b, s...)
}
func (z *bytesEncAppender) writestr(s string) {
z.b = append(z.b, s...)
}
func (z *bytesEncAppender) writeqstr(s string) {
z.b = append(append(append(z.b, '"'), s...), '"')
// z.b = append(z.b, '"')
// z.b = append(z.b, s...)
// z.b = append(z.b, '"')
}
func (z *bytesEncAppender) writen1(b1 byte) {
z.b = append(z.b, b1)
}
func (z *bytesEncAppender) writen2(b1, b2 byte) {
z.b = append(z.b, b1, b2)
}
func (z *bytesEncAppender) writen4(b [4]byte) {
z.b = append(z.b, b[:]...)
// z.b = append(z.b, b1, b2, b3, b4) // prevents inlining encWr.writen4
}
func (z *bytesEncAppender) writen8(b [8]byte) {
z.b = append(z.b, b[:]...)
// z.b = append(z.b, b[0], b[1], b[2], b[3], b[4], b[5], b[6], b[7])
}
func (z *bytesEncAppender) end() {
*(z.out) = z.b
}
func (z *bytesEncAppender) resetBytes(in []byte, out *[]byte) {
z.b = in[:0]
z.out = out
}
func (z *bytesEncAppender) resetIO(w io.Writer, bufsize int, blist *bytesFreeList) {
halt.errorStr("resetIO is unsupported by bytesEncAppender")
}
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