// A Buffer is a variable-sized buffer of bytes with Read and Write methods.
// The zero value for Buffer is an empty buffer ready to use.
type Buffer struct {
buf []byte // contents are the bytes buf[off : len(buf)]
off int // read at &buf[off], write at &buf[len(buf)]
runeBytes [utf8.UTFMax]byte // avoid allocation of slice on each WriteByte or Rune
bootstrap [64]byte // memory to hold first slice; helps small buffers (Printf) avoid allocation.
lastRead readOp // last read operation, so that Unread* can work correctly.
}
方法函數(shù)
// 返回buffer字節(jié)
func (b *Buffer) Bytes() []byte {}
// 返回字符串, 內(nèi)部調(diào)用Bytes方法
func (b *Buffer) String() string {}
// 返回buffer長度
func (b *Buffer) Len() int {}
// 截?cái)郻uffer
func (b *Buffer) Truncate(n int) {}
//重置buffer
func (b *Buffer) Reset() { b.Truncate(0) }
// buffer擴(kuò)容鲸沮，內(nèi)部調(diào)用grow, 對(duì)外函數(shù)
func (b *Buffer) Grow(n int) {}
// buffer擴(kuò)容
func (b *Buffer) grow(n int) int {
m := b.Len()
// If buffer is empty, reset to recover space.
if m == 0 && b.off != 0 {
b.Truncate(0)
}
if len(b.buf)+n > cap(b.buf) {
var buf []byte
if b.buf == nil && n <= len(b.bootstrap) {
buf = b.bootstrap[0:]
} else if m+n <= cap(b.buf)/2 {
// We can slide things down instead of allocating a new
// slice. We only need m+n <= cap(b.buf) to slide, but
// we instead let capacity get twice as large so we
// don't spend all our time copying.
copy(b.buf[:], b.buf[b.off:])
buf = b.buf[:m]
} else {
// not enough space anywhere
buf = makeSlice(2*cap(b.buf) + n) // 重新申請(qǐng)內(nèi)存
copy(buf, b.buf[b.off:])
}
b.buf = buf
b.off = 0
}
b.buf = b.buf[0 : b.off+m+n]
return b.off + m
}
// 寫函數(shù)
func (b *Buffer) Write(p []byte) (n int, err error) {
b.lastRead = opInvalid
m := b.grow(len(p))
return copy(b.buf[m:], p), nil
}
// 同上
func (b *Buffer) WriteString(s string) (n int, err error) {}
