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package core
import (
"errors"
"io"
"strings"
)
const (
refPrefix = "refs/"
refHeadPrefix = refPrefix + "heads/"
refTagPrefix = refPrefix + "tags/"
refRemotePrefix = refPrefix + "remotes/"
refNotePrefix = refPrefix + "notes/"
symrefPrefix = "ref: "
maxResolveRecursion = 1024
)
var (
ErrMaxResolveRecursion = errors.New("max. recursion level reached")
ErrReferenceNotFound = errors.New("reference not found")
)
// ReferenceType reference type's
type ReferenceType int8
const (
InvalidReference ReferenceType = 0
HashReference ReferenceType = 1
SymbolicReference ReferenceType = 2
)
// ReferenceName reference name's
type ReferenceName string
const (
HEAD ReferenceName = "HEAD"
)
// Reference is a representation of git reference
type Reference struct {
t ReferenceType
n ReferenceName
h Hash
target ReferenceName
}
// NewReferenceFromStrings creates a reference from name and target as string,
// the resulting reference can be a SymbolicReference or a HashReference base
// on the target provided
func NewReferenceFromStrings(name, target string) *Reference {
n := ReferenceName(name)
if strings.HasPrefix(target, symrefPrefix) {
target := ReferenceName(target[len(symrefPrefix):])
return NewSymbolicReference(n, target)
}
return NewHashReference(n, NewHash(target))
}
// NewSymbolicReference creates a new SymbolicReference reference
func NewSymbolicReference(n, target ReferenceName) *Reference {
return &Reference{
t: SymbolicReference,
n: n,
target: target,
}
}
// NewHashReference creates a new HashReference reference
func NewHashReference(n ReferenceName, h Hash) *Reference {
return &Reference{
t: HashReference,
n: n,
h: h,
}
}
// Type return the type of a reference
func (r *Reference) Type() ReferenceType {
return r.t
}
// Name return the name of a reference
func (r *Reference) Name() ReferenceName {
return r.n
}
// Hash return the hash of a hash reference
func (r *Reference) Hash() Hash {
return r.h
}
// Target return the target of a symbolic reference
func (r *Reference) Target() ReferenceName {
return r.target
}
// IsBranch check if a reference is a branch
func (r *Reference) IsBranch() bool {
return strings.HasPrefix(string(r.n), refHeadPrefix)
}
// IsNote check if a reference is a note
func (r *Reference) IsNote() bool {
return strings.HasPrefix(string(r.n), refNotePrefix)
}
// IsRemote check if a reference is a remote
func (r *Reference) IsRemote() bool {
return strings.HasPrefix(string(r.n), refRemotePrefix)
}
// IsTag check if a reference is a tag
func (r *Reference) IsTag() bool {
return strings.HasPrefix(string(r.n), refTagPrefix)
}
// ReferenceSliceIter implements ReferenceIter. It iterates over a series of
// references stored in a slice and yields each one in turn when Next() is
// called.
//
// The ReferenceSliceIter must be closed with a call to Close() when it is no
// longer needed.
type ReferenceSliceIter struct {
series []*Reference
pos int
}
// NewReferenceSliceIter returns a reference iterator for the given slice of
// objects.
func NewReferenceSliceIter(series []*Reference) *ReferenceSliceIter {
return &ReferenceSliceIter{
series: series,
}
}
// Next returns the next reference from the iterator. If the iterator has
// reached the end it will return io.EOF as an error.
func (iter *ReferenceSliceIter) Next() (*Reference, error) {
if iter.pos >= len(iter.series) {
return nil, io.EOF
}
obj := iter.series[iter.pos]
iter.pos++
return obj, nil
}
// Close releases any resources used by the iterator.
func (iter *ReferenceSliceIter) Close() {
iter.pos = len(iter.series)
}
func ResolveReference(s ReferenceStorage, n ReferenceName) (*Reference, error) {
r, err := s.Get(n)
if err != nil || r == nil {
return r, err
}
return resolveReference(s, r, 0)
}
func resolveReference(s ReferenceStorage, r *Reference, recursion int) (*Reference, error) {
if r.Type() != SymbolicReference {
return r, nil
}
if recursion > maxResolveRecursion {
return nil, ErrMaxResolveRecursion
}
t, err := s.Get(r.Target())
if err != nil {
return nil, err
}
recursion++
return resolveReference(s, t, recursion)
}
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