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package furgit
import (
"bytes"
"errors"
"fmt"
"strconv"
)
// ObjectType mirrors Git's object type tags.
type ObjectType uint8
const (
// An invalid object.
ObjectTypeInvalid ObjectType = 0
// A commit object.
ObjectTypeCommit ObjectType = 1
// A tree object.
ObjectTypeTree ObjectType = 2
// A blob object.
ObjectTypeBlob ObjectType = 3
// An annotated tag object.
ObjectTypeTag ObjectType = 4
// An object type reserved for future use.
ObjectTypeFuture ObjectType = 5
// A packfile offset delta object. This is not typically exposed.
ObjectTypeOfsDelta ObjectType = 6
// A packfile reference delta object. This is not typically exposed.
ObjectTypeRefDelta ObjectType = 7
)
const (
objectTypeNameBlob = "blob"
objectTypeNameTree = "tree"
objectTypeNameCommit = "commit"
objectTypeNameTag = "tag"
)
// Object represents a Git object.
type Object interface {
ObjectType() ObjectType
}
// StoredObject describes a Git object with a known hash, such as
// one read from storage.
type StoredObject interface {
Object
Hash() Hash
}
func headerForType(ty ObjectType, body []byte) ([]byte, error) {
var tyStr string
switch ty {
case ObjectTypeBlob:
tyStr = objectTypeNameBlob
case ObjectTypeTree:
tyStr = objectTypeNameTree
case ObjectTypeCommit:
tyStr = objectTypeNameCommit
case ObjectTypeTag:
tyStr = objectTypeNameTag
case ObjectTypeInvalid, ObjectTypeFuture, ObjectTypeOfsDelta, ObjectTypeRefDelta:
return nil, fmt.Errorf("furgit: object: unsupported type %d", ty)
default:
return nil, fmt.Errorf("furgit: object: unsupported type %d", ty)
}
size := strconv.Itoa(len(body))
var buf bytes.Buffer
buf.Grow(len(tyStr) + len(size) + 1)
buf.WriteString(tyStr)
buf.WriteByte(' ')
buf.WriteString(size)
buf.WriteByte(0)
return buf.Bytes(), nil
}
func parseObjectBody(ty ObjectType, id Hash, body []byte, repo *Repository) (StoredObject, error) {
switch ty {
case ObjectTypeBlob:
return parseBlob(id, body)
case ObjectTypeTree:
return parseTree(id, body, repo)
case ObjectTypeCommit:
return parseCommit(id, body, repo)
case ObjectTypeTag:
return parseTag(id, body, repo)
case ObjectTypeInvalid, ObjectTypeFuture, ObjectTypeOfsDelta, ObjectTypeRefDelta:
return nil, fmt.Errorf("furgit: object: unsupported type %d", ty)
default:
return nil, fmt.Errorf("furgit: object: unknown type %d", ty)
}
}
// ReadObject resolves an ID.
func (repo *Repository) ReadObject(id Hash) (Object, error) {
obj, err := repo.looseRead(id)
if err == nil {
return obj, nil
}
if !errors.Is(err, ErrNotFound) {
return nil, err
}
obj, err = repo.packRead(id)
if errors.Is(err, ErrNotFound) {
return nil, ErrInvalidObject
}
return obj, err
}
// ReadObjectTypeSize reports the object type and size.
//
// Typicall, this is more efficient than reading the full object,
// as it avoids decompressing the entire object body.
func (repo *Repository) ReadObjectTypeSize(id Hash) (ObjectType, int64, error) {
ty, size, err := repo.looseTypeSize(id)
if err == nil {
return ty, size, nil
}
if !errors.Is(err, ErrNotFound) {
return ObjectTypeInvalid, 0, err
}
loc, err := repo.packIndexFind(id)
if err != nil {
if errors.Is(err, ErrNotFound) {
return ObjectTypeInvalid, 0, ErrInvalidObject
}
return ObjectTypeInvalid, 0, err
}
return repo.packTypeSizeAtLocation(loc, nil)
}
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