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package packfile
import (
"io"
"gopkg.in/src-d/go-git.v4/core"
)
// Stream implements ReadRecaller for the io.Reader of a packfile. This
// implementation keeps all remembered objects referenced in maps for
// quick access.
type Stream struct {
io.Reader
count int64
offsetToObject map[int64]core.Object
hashToObject map[core.Hash]core.Object
}
// NewStream returns a new Stream that reads form r.
func NewStream(r io.Reader) *Stream {
return &Stream{
Reader: r,
count: 0,
hashToObject: make(map[core.Hash]core.Object, 0),
offsetToObject: make(map[int64]core.Object, 0),
}
}
// Read reads up to len(p) bytes into p.
func (r *Stream) Read(p []byte) (n int, err error) {
n, err = r.Reader.Read(p)
r.count += int64(n)
return
}
// ReadByte reads a byte.
func (r *Stream) ReadByte() (byte, error) {
var p [1]byte
_, err := r.Reader.Read(p[:])
r.count++
return p[0], err
}
// Offset returns the number of bytes read.
func (r *Stream) Offset() (int64, error) {
return r.count, nil
}
// Remember stores references to the passed object to be used later by
// RecalByHash and RecallByOffset. It receives the object and the offset
// of its object entry in the packfile.
func (r *Stream) Remember(o int64, obj core.Object) error {
h := obj.Hash()
if _, ok := r.hashToObject[h]; ok {
return ErrDuplicatedObject.AddDetails("with hash %s", h)
}
r.hashToObject[h] = obj
if _, ok := r.offsetToObject[o]; ok {
return ErrDuplicatedObject.AddDetails("with offset %d", o)
}
r.offsetToObject[o] = obj
return nil
}
// ForgetAll forgets all previously remembered objects.
func (r *Stream) ForgetAll() {
r.hashToObject = make(map[core.Hash]core.Object)
r.offsetToObject = make(map[int64]core.Object)
}
// RecallByHash returns an object that has been previously Remember-ed by
// its hash.
func (r *Stream) RecallByHash(h core.Hash) (core.Object, error) {
obj, ok := r.hashToObject[h]
if !ok {
return nil, ErrCannotRecall.AddDetails("by hash %s", h)
}
return obj, nil
}
// RecallByOffset returns an object that has been previously Remember-ed by
// the offset of its object entry in the packfile.
func (r *Stream) RecallByOffset(o int64) (core.Object, error) {
obj, ok := r.offsetToObject[o]
if !ok {
return nil, ErrCannotRecall.AddDetails("no object found at offset %d", o)
}
return obj, nil
}
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