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package index
import (
"fmt"
"io"
"gopkg.in/src-d/go-git.v4/core"
"gopkg.in/src-d/go-git.v4/formats/idxfile"
"gopkg.in/src-d/go-git.v4/formats/packfile"
)
// Index is a database of objects and their offset in a packfile.
// Objects are identified by their hash.
type Index map[core.Hash]int64
// Decode decodes a idxfile into the Index
func (i *Index) Decode(r io.Reader) error {
d := idxfile.NewDecoder(r)
idx := &idxfile.Idxfile{}
if err := d.Decode(idx); err != nil {
return err
}
for _, e := range idx.Entries {
(*i)[e.Hash] = int64(e.Offset)
}
return nil
}
// NewFrompackfile returns a new index from a packfile reader.
func NewFromPackfile(r io.Reader) (Index, core.Hash, error) {
index := make(Index)
p := packfile.NewParser(r)
_, count, err := p.Header()
if err != nil {
return nil, core.ZeroHash, err
}
for i := 0; i < int(count); i++ {
h, err := p.NextObjectHeader()
if err = index.Set(core.ZeroHash, h.Offset); err != nil {
return nil, core.ZeroHash, err
}
}
hash, err := p.Checksum()
return index, hash, err
}
// Get returns the offset that an object has the packfile.
func (i Index) Get(h core.Hash) (int64, error) {
o, ok := i[h]
if !ok {
return 0, core.ErrObjectNotFound
}
return o, nil
}
// Set adds a new hash-offset pair to the index, or substitutes an existing one.
func (i Index) Set(h core.Hash, o int64) error {
if _, ok := i[h]; ok {
return fmt.Errorf("index.Set failed: duplicated key: %s", h)
}
i[h] = o
return nil
}
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