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-rw-r--r--src/bufio/bufio.go782
1 files changed, 782 insertions, 0 deletions
diff --git a/src/bufio/bufio.go b/src/bufio/bufio.go
new file mode 100644
index 0000000..6baf9b9
--- /dev/null
+++ b/src/bufio/bufio.go
@@ -0,0 +1,782 @@
+// Copyright 2009 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 bufio implements buffered I/O. It wraps an io.Reader or io.Writer
+// object, creating another object (Reader or Writer) that also implements
+// the interface but provides buffering and some help for textual I/O.
+package bufio
+
+import (
+ "bytes"
+ "errors"
+ "io"
+ "strings"
+ "unicode/utf8"
+)
+
+const (
+ defaultBufSize = 4096
+)
+
+var (
+ ErrInvalidUnreadByte = errors.New("bufio: invalid use of UnreadByte")
+ ErrInvalidUnreadRune = errors.New("bufio: invalid use of UnreadRune")
+ ErrBufferFull = errors.New("bufio: buffer full")
+ ErrNegativeCount = errors.New("bufio: negative count")
+)
+
+// Buffered input.
+
+// Reader implements buffering for an io.Reader object.
+type Reader struct {
+ buf []byte
+ rd io.Reader // reader provided by the client
+ r, w int // buf read and write positions
+ err error
+ lastByte int // last byte read for UnreadByte; -1 means invalid
+ lastRuneSize int // size of last rune read for UnreadRune; -1 means invalid
+}
+
+const minReadBufferSize = 16
+const maxConsecutiveEmptyReads = 100
+
+// NewReaderSize returns a new Reader whose buffer has at least the specified
+// size. If the argument io.Reader is already a Reader with large enough
+// size, it returns the underlying Reader.
+func NewReaderSize(rd io.Reader, size int) *Reader {
+ // Is it already a Reader?
+ b, ok := rd.(*Reader)
+ if ok && len(b.buf) >= size {
+ return b
+ }
+ if size < minReadBufferSize {
+ size = minReadBufferSize
+ }
+ r := new(Reader)
+ r.reset(make([]byte, size), rd)
+ return r
+}
+
+// NewReader returns a new Reader whose buffer has the default size.
+func NewReader(rd io.Reader) *Reader {
+ return NewReaderSize(rd, defaultBufSize)
+}
+
+// Size returns the size of the underlying buffer in bytes.
+func (b *Reader) Size() int { return len(b.buf) }
+
+// Reset discards any buffered data, resets all state, and switches
+// the buffered reader to read from r.
+func (b *Reader) Reset(r io.Reader) {
+ b.reset(b.buf, r)
+}
+
+func (b *Reader) reset(buf []byte, r io.Reader) {
+ *b = Reader{
+ buf: buf,
+ rd: r,
+ lastByte: -1,
+ lastRuneSize: -1,
+ }
+}
+
+var errNegativeRead = errors.New("bufio: reader returned negative count from Read")
+
+// fill reads a new chunk into the buffer.
+func (b *Reader) fill() {
+ // Slide existing data to beginning.
+ if b.r > 0 {
+ copy(b.buf, b.buf[b.r:b.w])
+ b.w -= b.r
+ b.r = 0
+ }
+
+ if b.w >= len(b.buf) {
+ panic("bufio: tried to fill full buffer")
+ }
+
+ // Read new data: try a limited number of times.
+ for i := maxConsecutiveEmptyReads; i > 0; i-- {
+ n, err := b.rd.Read(b.buf[b.w:])
+ if n < 0 {
+ panic(errNegativeRead)
+ }
+ b.w += n
+ if err != nil {
+ b.err = err
+ return
+ }
+ if n > 0 {
+ return
+ }
+ }
+ b.err = io.ErrNoProgress
+}
+
+func (b *Reader) readErr() error {
+ err := b.err
+ b.err = nil
+ return err
+}
+
+// Peek returns the next n bytes without advancing the reader. The bytes stop
+// being valid at the next read call. If Peek returns fewer than n bytes, it
+// also returns an error explaining why the read is short. The error is
+// ErrBufferFull if n is larger than b's buffer size.
+//
+// Calling Peek prevents a UnreadByte or UnreadRune call from succeeding
+// until the next read operation.
+func (b *Reader) Peek(n int) ([]byte, error) {
+ if n < 0 {
+ return nil, ErrNegativeCount
+ }
+
+ b.lastByte = -1
+ b.lastRuneSize = -1
+
+ for b.w-b.r < n && b.w-b.r < len(b.buf) && b.err == nil {
+ b.fill() // b.w-b.r < len(b.buf) => buffer is not full
+ }
+
+ if n > len(b.buf) {
+ return b.buf[b.r:b.w], ErrBufferFull
+ }
+
+ // 0 <= n <= len(b.buf)
+ var err error
+ if avail := b.w - b.r; avail < n {
+ // not enough data in buffer
+ n = avail
+ err = b.readErr()
+ if err == nil {
+ err = ErrBufferFull
+ }
+ }
+ return b.buf[b.r : b.r+n], err
+}
+
+// Discard skips the next n bytes, returning the number of bytes discarded.
+//
+// If Discard skips fewer than n bytes, it also returns an error.
+// If 0 <= n <= b.Buffered(), Discard is guaranteed to succeed without
+// reading from the underlying io.Reader.
+func (b *Reader) Discard(n int) (discarded int, err error) {
+ if n < 0 {
+ return 0, ErrNegativeCount
+ }
+ if n == 0 {
+ return
+ }
+ remain := n
+ for {
+ skip := b.Buffered()
+ if skip == 0 {
+ b.fill()
+ skip = b.Buffered()
+ }
+ if skip > remain {
+ skip = remain
+ }
+ b.r += skip
+ remain -= skip
+ if remain == 0 {
+ return n, nil
+ }
+ if b.err != nil {
+ return n - remain, b.readErr()
+ }
+ }
+}
+
+// Read reads data into p.
+// It returns the number of bytes read into p.
+// The bytes are taken from at most one Read on the underlying Reader,
+// hence n may be less than len(p).
+// To read exactly len(p) bytes, use io.ReadFull(b, p).
+// At EOF, the count will be zero and err will be io.EOF.
+func (b *Reader) Read(p []byte) (n int, err error) {
+ n = len(p)
+ if n == 0 {
+ if b.Buffered() > 0 {
+ return 0, nil
+ }
+ return 0, b.readErr()
+ }
+ if b.r == b.w {
+ if b.err != nil {
+ return 0, b.readErr()
+ }
+ if len(p) >= len(b.buf) {
+ // Large read, empty buffer.
+ // Read directly into p to avoid copy.
+ n, b.err = b.rd.Read(p)
+ if n < 0 {
+ panic(errNegativeRead)
+ }
+ if n > 0 {
+ b.lastByte = int(p[n-1])
+ b.lastRuneSize = -1
+ }
+ return n, b.readErr()
+ }
+ // One read.
+ // Do not use b.fill, which will loop.
+ b.r = 0
+ b.w = 0
+ n, b.err = b.rd.Read(b.buf)
+ if n < 0 {
+ panic(errNegativeRead)
+ }
+ if n == 0 {
+ return 0, b.readErr()
+ }
+ b.w += n
+ }
+
+ // copy as much as we can
+ n = copy(p, b.buf[b.r:b.w])
+ b.r += n
+ b.lastByte = int(b.buf[b.r-1])
+ b.lastRuneSize = -1
+ return n, nil
+}
+
+// ReadByte reads and returns a single byte.
+// If no byte is available, returns an error.
+func (b *Reader) ReadByte() (byte, error) {
+ b.lastRuneSize = -1
+ for b.r == b.w {
+ if b.err != nil {
+ return 0, b.readErr()
+ }
+ b.fill() // buffer is empty
+ }
+ c := b.buf[b.r]
+ b.r++
+ b.lastByte = int(c)
+ return c, nil
+}
+
+// UnreadByte unreads the last byte. Only the most recently read byte can be unread.
+//
+// UnreadByte returns an error if the most recent method called on the
+// Reader was not a read operation. Notably, Peek is not considered a
+// read operation.
+func (b *Reader) UnreadByte() error {
+ if b.lastByte < 0 || b.r == 0 && b.w > 0 {
+ return ErrInvalidUnreadByte
+ }
+ // b.r > 0 || b.w == 0
+ if b.r > 0 {
+ b.r--
+ } else {
+ // b.r == 0 && b.w == 0
+ b.w = 1
+ }
+ b.buf[b.r] = byte(b.lastByte)
+ b.lastByte = -1
+ b.lastRuneSize = -1
+ return nil
+}
+
+// ReadRune reads a single UTF-8 encoded Unicode character and returns the
+// rune and its size in bytes. If the encoded rune is invalid, it consumes one byte
+// and returns unicode.ReplacementChar (U+FFFD) with a size of 1.
+func (b *Reader) ReadRune() (r rune, size int, err error) {
+ for b.r+utf8.UTFMax > b.w && !utf8.FullRune(b.buf[b.r:b.w]) && b.err == nil && b.w-b.r < len(b.buf) {
+ b.fill() // b.w-b.r < len(buf) => buffer is not full
+ }
+ b.lastRuneSize = -1
+ if b.r == b.w {
+ return 0, 0, b.readErr()
+ }
+ r, size = rune(b.buf[b.r]), 1
+ if r >= utf8.RuneSelf {
+ r, size = utf8.DecodeRune(b.buf[b.r:b.w])
+ }
+ b.r += size
+ b.lastByte = int(b.buf[b.r-1])
+ b.lastRuneSize = size
+ return r, size, nil
+}
+
+// UnreadRune unreads the last rune. If the most recent method called on
+// the Reader was not a ReadRune, UnreadRune returns an error. (In this
+// regard it is stricter than UnreadByte, which will unread the last byte
+// from any read operation.)
+func (b *Reader) UnreadRune() error {
+ if b.lastRuneSize < 0 || b.r < b.lastRuneSize {
+ return ErrInvalidUnreadRune
+ }
+ b.r -= b.lastRuneSize
+ b.lastByte = -1
+ b.lastRuneSize = -1
+ return nil
+}
+
+// Buffered returns the number of bytes that can be read from the current buffer.
+func (b *Reader) Buffered() int { return b.w - b.r }
+
+// ReadSlice reads until the first occurrence of delim in the input,
+// returning a slice pointing at the bytes in the buffer.
+// The bytes stop being valid at the next read.
+// If ReadSlice encounters an error before finding a delimiter,
+// it returns all the data in the buffer and the error itself (often io.EOF).
+// ReadSlice fails with error ErrBufferFull if the buffer fills without a delim.
+// Because the data returned from ReadSlice will be overwritten
+// by the next I/O operation, most clients should use
+// ReadBytes or ReadString instead.
+// ReadSlice returns err != nil if and only if line does not end in delim.
+func (b *Reader) ReadSlice(delim byte) (line []byte, err error) {
+ s := 0 // search start index
+ for {
+ // Search buffer.
+ if i := bytes.IndexByte(b.buf[b.r+s:b.w], delim); i >= 0 {
+ i += s
+ line = b.buf[b.r : b.r+i+1]
+ b.r += i + 1
+ break
+ }
+
+ // Pending error?
+ if b.err != nil {
+ line = b.buf[b.r:b.w]
+ b.r = b.w
+ err = b.readErr()
+ break
+ }
+
+ // Buffer full?
+ if b.Buffered() >= len(b.buf) {
+ b.r = b.w
+ line = b.buf
+ err = ErrBufferFull
+ break
+ }
+
+ s = b.w - b.r // do not rescan area we scanned before
+
+ b.fill() // buffer is not full
+ }
+
+ // Handle last byte, if any.
+ if i := len(line) - 1; i >= 0 {
+ b.lastByte = int(line[i])
+ b.lastRuneSize = -1
+ }
+
+ return
+}
+
+// ReadLine is a low-level line-reading primitive. Most callers should use
+// ReadBytes('\n') or ReadString('\n') instead or use a Scanner.
+//
+// ReadLine tries to return a single line, not including the end-of-line bytes.
+// If the line was too long for the buffer then isPrefix is set and the
+// beginning of the line is returned. The rest of the line will be returned
+// from future calls. isPrefix will be false when returning the last fragment
+// of the line. The returned buffer is only valid until the next call to
+// ReadLine. ReadLine either returns a non-nil line or it returns an error,
+// never both.
+//
+// The text returned from ReadLine does not include the line end ("\r\n" or "\n").
+// No indication or error is given if the input ends without a final line end.
+// Calling UnreadByte after ReadLine will always unread the last byte read
+// (possibly a character belonging to the line end) even if that byte is not
+// part of the line returned by ReadLine.
+func (b *Reader) ReadLine() (line []byte, isPrefix bool, err error) {
+ line, err = b.ReadSlice('\n')
+ if err == ErrBufferFull {
+ // Handle the case where "\r\n" straddles the buffer.
+ if len(line) > 0 && line[len(line)-1] == '\r' {
+ // Put the '\r' back on buf and drop it from line.
+ // Let the next call to ReadLine check for "\r\n".
+ if b.r == 0 {
+ // should be unreachable
+ panic("bufio: tried to rewind past start of buffer")
+ }
+ b.r--
+ line = line[:len(line)-1]
+ }
+ return line, true, nil
+ }
+
+ if len(line) == 0 {
+ if err != nil {
+ line = nil
+ }
+ return
+ }
+ err = nil
+
+ if line[len(line)-1] == '\n' {
+ drop := 1
+ if len(line) > 1 && line[len(line)-2] == '\r' {
+ drop = 2
+ }
+ line = line[:len(line)-drop]
+ }
+ return
+}
+
+// collectFragments reads until the first occurrence of delim in the input. It
+// returns (slice of full buffers, remaining bytes before delim, total number
+// of bytes in the combined first two elements, error).
+// The complete result is equal to
+// `bytes.Join(append(fullBuffers, finalFragment), nil)`, which has a
+// length of `totalLen`. The result is structured in this way to allow callers
+// to minimize allocations and copies.
+func (b *Reader) collectFragments(delim byte) (fullBuffers [][]byte, finalFragment []byte, totalLen int, err error) {
+ var frag []byte
+ // Use ReadSlice to look for delim, accumulating full buffers.
+ for {
+ var e error
+ frag, e = b.ReadSlice(delim)
+ if e == nil { // got final fragment
+ break
+ }
+ if e != ErrBufferFull { // unexpected error
+ err = e
+ break
+ }
+
+ // Make a copy of the buffer.
+ buf := make([]byte, len(frag))
+ copy(buf, frag)
+ fullBuffers = append(fullBuffers, buf)
+ totalLen += len(buf)
+ }
+
+ totalLen += len(frag)
+ return fullBuffers, frag, totalLen, err
+}
+
+// ReadBytes reads until the first occurrence of delim in the input,
+// returning a slice containing the data up to and including the delimiter.
+// If ReadBytes encounters an error before finding a delimiter,
+// it returns the data read before the error and the error itself (often io.EOF).
+// ReadBytes returns err != nil if and only if the returned data does not end in
+// delim.
+// For simple uses, a Scanner may be more convenient.
+func (b *Reader) ReadBytes(delim byte) ([]byte, error) {
+ full, frag, n, err := b.collectFragments(delim)
+ // Allocate new buffer to hold the full pieces and the fragment.
+ buf := make([]byte, n)
+ n = 0
+ // Copy full pieces and fragment in.
+ for i := range full {
+ n += copy(buf[n:], full[i])
+ }
+ copy(buf[n:], frag)
+ return buf, err
+}
+
+// ReadString reads until the first occurrence of delim in the input,
+// returning a string containing the data up to and including the delimiter.
+// If ReadString encounters an error before finding a delimiter,
+// it returns the data read before the error and the error itself (often io.EOF).
+// ReadString returns err != nil if and only if the returned data does not end in
+// delim.
+// For simple uses, a Scanner may be more convenient.
+func (b *Reader) ReadString(delim byte) (string, error) {
+ full, frag, n, err := b.collectFragments(delim)
+ // Allocate new buffer to hold the full pieces and the fragment.
+ var buf strings.Builder
+ buf.Grow(n)
+ // Copy full pieces and fragment in.
+ for _, fb := range full {
+ buf.Write(fb)
+ }
+ buf.Write(frag)
+ return buf.String(), err
+}
+
+// WriteTo implements io.WriterTo.
+// This may make multiple calls to the Read method of the underlying Reader.
+// If the underlying reader supports the WriteTo method,
+// this calls the underlying WriteTo without buffering.
+func (b *Reader) WriteTo(w io.Writer) (n int64, err error) {
+ n, err = b.writeBuf(w)
+ if err != nil {
+ return
+ }
+
+ if r, ok := b.rd.(io.WriterTo); ok {
+ m, err := r.WriteTo(w)
+ n += m
+ return n, err
+ }
+
+ if w, ok := w.(io.ReaderFrom); ok {
+ m, err := w.ReadFrom(b.rd)
+ n += m
+ return n, err
+ }
+
+ if b.w-b.r < len(b.buf) {
+ b.fill() // buffer not full
+ }
+
+ for b.r < b.w {
+ // b.r < b.w => buffer is not empty
+ m, err := b.writeBuf(w)
+ n += m
+ if err != nil {
+ return n, err
+ }
+ b.fill() // buffer is empty
+ }
+
+ if b.err == io.EOF {
+ b.err = nil
+ }
+
+ return n, b.readErr()
+}
+
+var errNegativeWrite = errors.New("bufio: writer returned negative count from Write")
+
+// writeBuf writes the Reader's buffer to the writer.
+func (b *Reader) writeBuf(w io.Writer) (int64, error) {
+ n, err := w.Write(b.buf[b.r:b.w])
+ if n < 0 {
+ panic(errNegativeWrite)
+ }
+ b.r += n
+ return int64(n), err
+}
+
+// buffered output
+
+// Writer implements buffering for an io.Writer object.
+// If an error occurs writing to a Writer, no more data will be
+// accepted and all subsequent writes, and Flush, will return the error.
+// After all data has been written, the client should call the
+// Flush method to guarantee all data has been forwarded to
+// the underlying io.Writer.
+type Writer struct {
+ err error
+ buf []byte
+ n int
+ wr io.Writer
+}
+
+// NewWriterSize returns a new Writer whose buffer has at least the specified
+// size. If the argument io.Writer is already a Writer with large enough
+// size, it returns the underlying Writer.
+func NewWriterSize(w io.Writer, size int) *Writer {
+ // Is it already a Writer?
+ b, ok := w.(*Writer)
+ if ok && len(b.buf) >= size {
+ return b
+ }
+ if size <= 0 {
+ size = defaultBufSize
+ }
+ return &Writer{
+ buf: make([]byte, size),
+ wr: w,
+ }
+}
+
+// NewWriter returns a new Writer whose buffer has the default size.
+func NewWriter(w io.Writer) *Writer {
+ return NewWriterSize(w, defaultBufSize)
+}
+
+// Size returns the size of the underlying buffer in bytes.
+func (b *Writer) Size() int { return len(b.buf) }
+
+// Reset discards any unflushed buffered data, clears any error, and
+// resets b to write its output to w.
+func (b *Writer) Reset(w io.Writer) {
+ b.err = nil
+ b.n = 0
+ b.wr = w
+}
+
+// Flush writes any buffered data to the underlying io.Writer.
+func (b *Writer) Flush() error {
+ if b.err != nil {
+ return b.err
+ }
+ if b.n == 0 {
+ return nil
+ }
+ n, err := b.wr.Write(b.buf[0:b.n])
+ if n < b.n && err == nil {
+ err = io.ErrShortWrite
+ }
+ if err != nil {
+ if n > 0 && n < b.n {
+ copy(b.buf[0:b.n-n], b.buf[n:b.n])
+ }
+ b.n -= n
+ b.err = err
+ return err
+ }
+ b.n = 0
+ return nil
+}
+
+// Available returns how many bytes are unused in the buffer.
+func (b *Writer) Available() int { return len(b.buf) - b.n }
+
+// Buffered returns the number of bytes that have been written into the current buffer.
+func (b *Writer) Buffered() int { return b.n }
+
+// Write writes the contents of p into the buffer.
+// It returns the number of bytes written.
+// If nn < len(p), it also returns an error explaining
+// why the write is short.
+func (b *Writer) Write(p []byte) (nn int, err error) {
+ for len(p) > b.Available() && b.err == nil {
+ var n int
+ if b.Buffered() == 0 {
+ // Large write, empty buffer.
+ // Write directly from p to avoid copy.
+ n, b.err = b.wr.Write(p)
+ } else {
+ n = copy(b.buf[b.n:], p)
+ b.n += n
+ b.Flush()
+ }
+ nn += n
+ p = p[n:]
+ }
+ if b.err != nil {
+ return nn, b.err
+ }
+ n := copy(b.buf[b.n:], p)
+ b.n += n
+ nn += n
+ return nn, nil
+}
+
+// WriteByte writes a single byte.
+func (b *Writer) WriteByte(c byte) error {
+ if b.err != nil {
+ return b.err
+ }
+ if b.Available() <= 0 && b.Flush() != nil {
+ return b.err
+ }
+ b.buf[b.n] = c
+ b.n++
+ return nil
+}
+
+// WriteRune writes a single Unicode code point, returning
+// the number of bytes written and any error.
+func (b *Writer) WriteRune(r rune) (size int, err error) {
+ if r < utf8.RuneSelf {
+ err = b.WriteByte(byte(r))
+ if err != nil {
+ return 0, err
+ }
+ return 1, nil
+ }
+ if b.err != nil {
+ return 0, b.err
+ }
+ n := b.Available()
+ if n < utf8.UTFMax {
+ if b.Flush(); b.err != nil {
+ return 0, b.err
+ }
+ n = b.Available()
+ if n < utf8.UTFMax {
+ // Can only happen if buffer is silly small.
+ return b.WriteString(string(r))
+ }
+ }
+ size = utf8.EncodeRune(b.buf[b.n:], r)
+ b.n += size
+ return size, nil
+}
+
+// WriteString writes a string.
+// It returns the number of bytes written.
+// If the count is less than len(s), it also returns an error explaining
+// why the write is short.
+func (b *Writer) WriteString(s string) (int, error) {
+ nn := 0
+ for len(s) > b.Available() && b.err == nil {
+ n := copy(b.buf[b.n:], s)
+ b.n += n
+ nn += n
+ s = s[n:]
+ b.Flush()
+ }
+ if b.err != nil {
+ return nn, b.err
+ }
+ n := copy(b.buf[b.n:], s)
+ b.n += n
+ nn += n
+ return nn, nil
+}
+
+// ReadFrom implements io.ReaderFrom. If the underlying writer
+// supports the ReadFrom method, and b has no buffered data yet,
+// this calls the underlying ReadFrom without buffering.
+func (b *Writer) ReadFrom(r io.Reader) (n int64, err error) {
+ if b.err != nil {
+ return 0, b.err
+ }
+ if b.Buffered() == 0 {
+ if w, ok := b.wr.(io.ReaderFrom); ok {
+ n, err = w.ReadFrom(r)
+ b.err = err
+ return n, err
+ }
+ }
+ var m int
+ for {
+ if b.Available() == 0 {
+ if err1 := b.Flush(); err1 != nil {
+ return n, err1
+ }
+ }
+ nr := 0
+ for nr < maxConsecutiveEmptyReads {
+ m, err = r.Read(b.buf[b.n:])
+ if m != 0 || err != nil {
+ break
+ }
+ nr++
+ }
+ if nr == maxConsecutiveEmptyReads {
+ return n, io.ErrNoProgress
+ }
+ b.n += m
+ n += int64(m)
+ if err != nil {
+ break
+ }
+ }
+ if err == io.EOF {
+ // If we filled the buffer exactly, flush preemptively.
+ if b.Available() == 0 {
+ err = b.Flush()
+ } else {
+ err = nil
+ }
+ }
+ return n, err
+}
+
+// buffered input and output
+
+// ReadWriter stores pointers to a Reader and a Writer.
+// It implements io.ReadWriter.
+type ReadWriter struct {
+ *Reader
+ *Writer
+}
+
+// NewReadWriter allocates a new ReadWriter that dispatches to r and w.
+func NewReadWriter(r *Reader, w *Writer) *ReadWriter {
+ return &ReadWriter{r, w}
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-16 00:27:36 +0000