bufio

Documentation

Overview

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.

Index

• Variables
• type ReadWriter
  • func NewReadWriter(r *Reader, w *Writer) *ReadWriter
• type Reader
  • func NewReader(rd io.Reader) *Reader
  • func NewReaderSize(rd io.Reader, size int) *Reader
  • func (b *Reader) Buffered() int
  • func (b *Reader) Peek(n int) ([]byte, error)
  • func (b *Reader) Read(p []byte) (n int, err error)
  • func (b *Reader) ReadByte() (c byte, err error)
  • func (b *Reader) ReadBytes(delim byte) (line []byte, err error)
  • func (b *Reader) ReadLine() (line []byte, isPrefix bool, err error)
  • func (b *Reader) ReadRune() (r rune, size int, err error)
  • func (b *Reader) ReadSlice(delim byte) (line []byte, err error)
  • func (b *Reader) ReadString(delim byte) (line string, err error)
  • func (b *Reader) UnreadByte() error
  • func (b *Reader) UnreadRune() error
  • func (b *Reader) WriteTo(w io.Writer) (n int64, err error)
• type Writer
  • func NewWriter(wr io.Writer) *Writer
  • func NewWriterSize(wr io.Writer, size int) *Writer
  • func (b *Writer) Available() int
  • func (b *Writer) Buffered() int
  • func (b *Writer) Flush() error
  • func (b *Writer) ReadFrom(r io.Reader) (n int64, err error)
  • func (b *Writer) Write(p []byte) (nn int, err error)
  • func (b *Writer) WriteByte(c byte) error
  • func (b *Writer) WriteRune(r rune) (size int, err error)
  • func (b *Writer) WriteString(s string) (int, error)

Variables

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")
)

Types

type ReadWriter

type ReadWriter struct {
	*Reader
	*Writer
}

ReadWriter stores pointers to a Reader and a Writer. It implements io.ReadWriter.

func NewReadWriter

func NewReadWriter(r *Reader, w *Writer) *ReadWriter

NewReadWriter allocates a new ReadWriter that dispatches to r and w.

type Reader

type Reader struct {
	// contains filtered or unexported fields
}

Reader implements buffering for an io.Reader object.

func NewReader

func NewReader(rd io.Reader) *Reader

NewReader returns a new Reader whose buffer has the default size.

func NewReaderSize

func NewReaderSize(rd io.Reader, size int) *Reader

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 (*Reader) Buffered

func (b *Reader) Buffered() int

Buffered returns the number of bytes that can be read from the current buffer.

func (*Reader) Peek

func (b *Reader) Peek(n int) ([]byte, error)

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.

func (*Reader) Read

func (b *Reader) Read(p []byte) (n int, err error)

Read reads data into p. It returns the number of bytes read into p. It calls Read at most once on the underlying Reader, hence n may be less than len(p). At EOF, the count will be zero and err will be io.EOF.

func (*Reader) ReadByte

func (b *Reader) ReadByte() (c byte, err error)

ReadByte reads and returns a single byte. If no byte is available, returns an error.

func (*Reader) ReadBytes

func (b *Reader) ReadBytes(delim byte) (line []byte, err error)

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.

func (*Reader) ReadLine

func (b *Reader) ReadLine() (line []byte, isPrefix bool, err error)

ReadLine is a low-level line-reading primitive. Most callers should use ReadBytes('\n') or ReadString('\n') instead.

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.

func (*Reader) ReadRune

func (b *Reader) ReadRune() (r rune, size int, err error)

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 (*Reader) ReadSlice

func (b *Reader) ReadSlice(delim byte) (line []byte, err error)

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 call. 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 (*Reader) ReadString

func (b *Reader) ReadString(delim byte) (line string, err error)

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.

func (*Reader) UnreadByte

func (b *Reader) UnreadByte() error

UnreadByte unreads the last byte. Only the most recently read byte can be unread.

func (*Reader) UnreadRune

func (b *Reader) UnreadRune() error

UnreadRune unreads the last rune. If the most recent read operation on the buffer 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 (*Reader) WriteTo

func (b *Reader) WriteTo(w io.Writer) (n int64, err error)

WriteTo implements io.WriterTo.

type Writer

type Writer struct {
	// contains filtered or unexported fields
}

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 will return the error.

func NewWriter

func NewWriter(wr io.Writer) *Writer

NewWriter returns a new Writer whose buffer has the default size.

func NewWriterSize

func NewWriterSize(wr io.Writer, size int) *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 (*Writer) Available

func (b *Writer) Available() int

Available returns how many bytes are unused in the buffer.

func (*Writer) Buffered

func (b *Writer) Buffered() int

Buffered returns the number of bytes that have been written into the current buffer.

func (*Writer) Flush

func (b *Writer) Flush() error

Flush writes any buffered data to the underlying io.Writer.

func (*Writer) ReadFrom

func (b *Writer) ReadFrom(r io.Reader) (n int64, err error)

ReadFrom implements io.ReaderFrom.

func (*Writer) Write

func (b *Writer) Write(p []byte) (nn int, err error)

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 (*Writer) WriteByte

func (b *Writer) WriteByte(c byte) error

WriteByte writes a single byte.

func (*Writer) WriteRune

func (b *Writer) WriteRune(r rune) (size int, err error)

WriteRune writes a single Unicode code point, returning the number of bytes written and any error.

func (*Writer) WriteString

func (b *Writer) WriteString(s string) (int, error)

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.