new plumbing package (#118)

* plumbing: now core was renamed to core, and formats and clients moved inside

1 files changed, 241 insertions, 0 deletions

diff --git a/plumbing/storer/object.go b/plumbing/storer/object.go
new file mode 100644
index 0000000..c7841b6
--- /dev/null
+++ b/plumbing/storer/object.go
@@ -0,0 +1,241 @@
+package storer
+
+import (
+	"errors"
+	"io"
+
+	"gopkg.in/src-d/go-git.v4/plumbing"
+)
+
+var (
+	//ErrStop is used to stop a ForEach function in an Iter
+	ErrStop = errors.New("stop iter")
+)
+
+// ObjectStorer generic storage of objects
+type ObjectStorer interface {
+	// NewObject returns a new plumbing.Object, the real type of the object can
+	// be a custom implementation or the defaul one, plumbing.MemoryObject
+	NewObject() plumbing.Object
+	// SetObject save an object into the storage, the object shuld be create
+	// with the NewObject, method, and file if the type is not supported.
+	SetObject(plumbing.Object) (plumbing.Hash, error)
+	// Object get an object by hash with the given plumbing.ObjectType.
+	// Implementors should return (nil, plumbing.ErrObjectNotFound) if an object
+	// doesn't exist with both the given hash and object type.
+	//
+	// Valid plumbing.ObjectType values are CommitObject, BlobObject, TagObject,
+	// TreeObject and AnyObject. If plumbing.AnyObject is given, the object must
+	// be looked up regardless of its type.
+	Object(plumbing.ObjectType, plumbing.Hash) (plumbing.Object, error)
+	// IterObjects returns a custom ObjectIter over all the object on the
+	// storage.
+	//
+	// Valid plumbing.ObjectType values are CommitObject, BlobObject, TagObject,
+	IterObjects(plumbing.ObjectType) (ObjectIter, error)
+}
+
+// Transactioner is a optional method for ObjectStorer, it enable transaction
+// base write and read operations in the storage
+type Transactioner interface {
+	// Begin starts a transaction.
+	Begin() Transaction
+}
+
+// PackfileWriter is a optional method for ObjectStorer, it enable direct write
+// of packfile to the storage
+type PackfileWriter interface {
+	// PackfileWriter retuns a writer for writing a packfile to the storage
+	//
+	// If the Storer not implements PackfileWriter the objects should be written
+	// using the Set method.
+	PackfileWriter() (io.WriteCloser, error)
+}
+
+// ObjectIter is a generic closable interface for iterating over objects.
+type ObjectIter interface {
+	Next() (plumbing.Object, error)
+	ForEach(func(plumbing.Object) error) error
+	Close()
+}
+
+// Transaction is an in-progress storage transaction. A transaction must end
+// with a call to Commit or Rollback.
+type Transaction interface {
+	SetObject(plumbing.Object) (plumbing.Hash, error)
+	Object(plumbing.ObjectType, plumbing.Hash) (plumbing.Object, error)
+	Commit() error
+	Rollback() error
+}
+
+// ObjectLookupIter implements ObjectIter. It iterates over a series of object
+// hashes and yields their associated objects by retrieving each one from
+// object storage. The retrievals are lazy and only occur when the iterator
+// moves forward with a call to Next().
+//
+// The ObjectLookupIter must be closed with a call to Close() when it is no
+// longer needed.
+type ObjectLookupIter struct {
+	storage ObjectStorer
+	series  []plumbing.Hash
+	t       plumbing.ObjectType
+	pos     int
+}
+
+// NewObjectLookupIter returns an object iterator given an object storage and
+// a slice of object hashes.
+func NewObjectLookupIter(
+	storage ObjectStorer, t plumbing.ObjectType, series []plumbing.Hash) *ObjectLookupIter {
+	return &ObjectLookupIter{
+		storage: storage,
+		series:  series,
+		t:       t,
+	}
+}
+
+// Next returns the next object from the iterator. If the iterator has reached
+// the end it will return io.EOF as an error. If the object can't be found in
+// the object storage, it will return plumbing.ErrObjectNotFound as an error.
+// If the object is retreieved successfully error will be nil.
+func (iter *ObjectLookupIter) Next() (plumbing.Object, error) {
+	if iter.pos >= len(iter.series) {
+		return nil, io.EOF
+	}
+
+	hash := iter.series[iter.pos]
+	obj, err := iter.storage.Object(iter.t, hash)
+	if err == nil {
+		iter.pos++
+	}
+
+	return obj, err
+}
+
+// ForEach call the cb function for each object 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 *ObjectLookupIter) ForEach(cb func(plumbing.Object) error) error {
+	return ForEachIterator(iter, cb)
+}
+
+// Close releases any resources used by the iterator.
+func (iter *ObjectLookupIter) Close() {
+	iter.pos = len(iter.series)
+}
+
+// ObjectSliceIter implements ObjectIter. It iterates over a series of objects
+// stored in a slice and yields each one in turn when Next() is called.
+//
+// The ObjectSliceIter must be closed with a call to Close() when it is no
+// longer needed.
+type ObjectSliceIter struct {
+	series []plumbing.Object
+	pos    int
+}
+
+// NewObjectSliceIter returns an object iterator for the given slice of objects.
+func NewObjectSliceIter(series []plumbing.Object) *ObjectSliceIter {
+	return &ObjectSliceIter{
+		series: series,
+	}
+}
+
+// Next returns the next object from the iterator. If the iterator has reached
+// the end it will return io.EOF as an error. If the object is retreieved
+// successfully error will be nil.
+func (iter *ObjectSliceIter) Next() (plumbing.Object, error) {
+	if len(iter.series) == 0 {
+		return nil, io.EOF
+	}
+
+	obj := iter.series[0]
+	iter.series = iter.series[1:]
+
+	return obj, nil
+}
+
+// ForEach call the cb function for each object 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 *ObjectSliceIter) ForEach(cb func(plumbing.Object) error) error {
+	return ForEachIterator(iter, cb)
+}
+
+// Close releases any resources used by the iterator.
+func (iter *ObjectSliceIter) Close() {
+	iter.series = []plumbing.Object{}
+}
+
+// MultiObjectIter implements ObjectIter. It iterates over several ObjectIter,
+//
+// The MultiObjectIter must be closed with a call to Close() when it is no
+// longer needed.
+type MultiObjectIter struct {
+	iters []ObjectIter
+	pos   int
+}
+
+// NewMultiObjectIter returns an object iterator for the given slice of objects.
+func NewMultiObjectIter(iters []ObjectIter) ObjectIter {
+	return &MultiObjectIter{iters: iters}
+}
+
+// Next returns the next object from the iterator, if one iterator reach io.EOF
+// is removed and the next one is used.
+func (iter *MultiObjectIter) Next() (plumbing.Object, error) {
+	if len(iter.iters) == 0 {
+		return nil, io.EOF
+	}
+
+	obj, err := iter.iters[0].Next()
+	if err == io.EOF {
+		iter.iters[0].Close()
+		iter.iters = iter.iters[1:]
+		return iter.Next()
+	}
+
+	return obj, err
+}
+
+// ForEach call the cb function for each object 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 *MultiObjectIter) ForEach(cb func(plumbing.Object) error) error {
+	return ForEachIterator(iter, cb)
+}
+
+// Close releases any resources used by the iterator.
+func (iter *MultiObjectIter) Close() {
+	for _, i := range iter.iters {
+		i.Close()
+	}
+}
+
+type bareIterator interface {
+	Next() (plumbing.Object, error)
+	Close()
+}
+
+// ForEachIterator is a helper function to build iterators without need to
+// rewrite the same ForEach function each time.
+func ForEachIterator(iter bareIterator, cb func(plumbing.Object) error) error {
+	defer iter.Close()
+	for {
+		obj, err := iter.Next()
+		if err != nil {
+			if err == io.EOF {
+				return nil
+			}
+
+			return err
+		}
+
+		if err := cb(obj); err != nil {
+			if err == ErrStop {
+				return nil
+			}
+
+			return err
+		}
+	}
+}