package storer import ( "errors" "io" "gopkg.in/src-d/go-git.v4/plumbing" ) const MaxResolveRecursion = 1024 // ErrMaxResolveRecursion is returned by ResolveReference is MaxResolveRecursion // is exceeded var ErrMaxResolveRecursion = errors.New("max. recursion level reached") // ReferenceStorer is a generic storage of references. type ReferenceStorer interface { SetReference(*plumbing.Reference) error Reference(plumbing.ReferenceName) (*plumbing.Reference, error) IterReferences() (ReferenceIter, error) RemoveReference(plumbing.ReferenceName) error } // ReferenceIter is a generic closable interface for iterating over references. type ReferenceIter interface { Next() (*plumbing.Reference, error) ForEach(func(*plumbing.Reference) error) error Close() } // 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 []*plumbing.Reference pos int } // NewReferenceSliceIter returns a reference iterator for the given slice of // objects. func NewReferenceSliceIter(series []*plumbing.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() (*plumbing.Reference, error) { if iter.pos >= len(iter.series) { return nil, io.EOF } obj := iter.series[iter.pos] iter.pos++ return obj, nil } // ForEach call the cb function for each reference contained on this iter until // an error happends or the end of the iter is reached. If ErrStop is sent // the iteration is stop but no error is returned. The iterator is closed. func (iter *ReferenceSliceIter) ForEach(cb func(*plumbing.Reference) error) error { defer iter.Close() for _, r := range iter.series { if err := cb(r); err != nil { if err == ErrStop { return nil } return err } } return nil } // Close releases any resources used by the iterator. func (iter *ReferenceSliceIter) Close() { iter.pos = len(iter.series) } // ResolveReference resolves a SymbolicReference to a HashReference. func ResolveReference(s ReferenceStorer, n plumbing.ReferenceName) (*plumbing.Reference, error) { r, err := s.Reference(n) if err != nil || r == nil { return r, err } return resolveReference(s, r, 0) } func resolveReference(s ReferenceStorer, r *plumbing.Reference, recursion int) (*plumbing.Reference, error) { if r.Type() != plumbing.SymbolicReference { return r, nil } if recursion > MaxResolveRecursion { return nil, ErrMaxResolveRecursion } t, err := s.Reference(r.Target()) if err != nil { return nil, err } recursion++ return resolveReference(s, t, recursion) }