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package plumbing
import (
"bytes"
"io"
)
// MemoryObject on memory Object implementation
type MemoryObject struct {
t ObjectType
h Hash
cont []byte
sz int64
}
// Hash returns the object Hash, the hash is calculated on-the-fly the first
// time it's called, in all subsequent calls the same Hash is returned even
// if the type or the content have changed. The Hash is only generated if the
// size of the content is exactly the object size.
func (o *MemoryObject) Hash() Hash {
if o.h == ZeroHash && int64(len(o.cont)) == o.sz {
o.h = ComputeHash(o.t, o.cont)
}
return o.h
}
// Type returns the ObjectType
func (o *MemoryObject) Type() ObjectType { return o.t }
// SetType sets the ObjectType
func (o *MemoryObject) SetType(t ObjectType) { o.t = t }
// Size returns the size of the object
func (o *MemoryObject) Size() int64 { return o.sz }
// SetSize set the object size, a content of the given size should be written
// afterwards
func (o *MemoryObject) SetSize(s int64) { o.sz = s }
// Reader returns an io.ReadCloser used to read the object's content.
//
// For a MemoryObject, this reader is seekable.
func (o *MemoryObject) Reader() (io.ReadCloser, error) {
return nopCloser{bytes.NewReader(o.cont)}, nil
}
// Writer returns a ObjectWriter used to write the object's content.
func (o *MemoryObject) Writer() (io.WriteCloser, error) {
return o, nil
}
func (o *MemoryObject) Write(p []byte) (n int, err error) {
o.cont = append(o.cont, p...)
o.sz = int64(len(o.cont))
return len(p), nil
}
// Close releases any resources consumed by the object when it is acting as a
// ObjectWriter.
func (o *MemoryObject) Close() error { return nil }
// nopCloser exposes the extra methods of bytes.Reader while nopping Close().
//
// This allows clients to attempt seeking in a cached Blob's Reader.
type nopCloser struct {
*bytes.Reader
}
// Close does nothing.
func (nc nopCloser) Close() error { return nil }
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