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author | Manjunath Kudlur <keveman@gmail.com> | 2015-11-06 16:27:58 -0800 |
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committer | Manjunath Kudlur <keveman@gmail.com> | 2015-11-06 16:27:58 -0800 |
commit | f41959ccb2d9d4c722fe8fc3351401d53bcf4900 (patch) | |
tree | ef0ca22cb2a5ac4bdec9d080d8e0788a53ed496d /tensorflow/core/lib/io/iterator.h |
TensorFlow: Initial commit of TensorFlow library.
TensorFlow is an open source software library for numerical computation
using data flow graphs.
Base CL: 107276108
Diffstat (limited to 'tensorflow/core/lib/io/iterator.h')
-rw-r--r-- | tensorflow/core/lib/io/iterator.h | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/tensorflow/core/lib/io/iterator.h b/tensorflow/core/lib/io/iterator.h new file mode 100644 index 0000000000..603a2f95fe --- /dev/null +++ b/tensorflow/core/lib/io/iterator.h @@ -0,0 +1,93 @@ +// Copyright (c) 2011 The LevelDB Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. See the AUTHORS file for names of contributors. +// +// An iterator yields a sequence of key/value pairs from a source. +// The following class defines the interface. Multiple implementations +// are provided by this library. In particular, iterators are provided +// to access the contents of a Table or a DB. +// +// Multiple threads can invoke const methods on an Iterator without +// external synchronization, but if any of the threads may call a +// non-const method, all threads accessing the same Iterator must use +// external synchronization. + +#ifndef TENSORFLOW_LIB_IO_ITERATOR_H_ +#define TENSORFLOW_LIB_IO_ITERATOR_H_ + +#include "tensorflow/core/lib/core/stringpiece.h" +#include "tensorflow/core/public/status.h" + +namespace tensorflow { +namespace table { + +class Iterator { + public: + Iterator(); + virtual ~Iterator(); + + // An iterator is either positioned at a key/value pair, or + // not valid. This method returns true iff the iterator is valid. + virtual bool Valid() const = 0; + + // Position at the first key in the source. The iterator is Valid() + // after this call iff the source is not empty. + virtual void SeekToFirst() = 0; + + // Position at the first key in the source that is at or past target. + // The iterator is Valid() after this call iff the source contains + // an entry that comes at or past target. + virtual void Seek(const StringPiece& target) = 0; + + // Moves to the next entry in the source. After this call, Valid() is + // true iff the iterator was not positioned at the last entry in the source. + // REQUIRES: Valid() + virtual void Next() = 0; + + // Return the key for the current entry. The underlying storage for + // the returned slice is valid only until the next modification of + // the iterator. + // REQUIRES: Valid() + virtual StringPiece key() const = 0; + + // Return the value for the current entry. The underlying storage for + // the returned slice is valid only until the next modification of + // the iterator. + // REQUIRES: Valid() + virtual StringPiece value() const = 0; + + // If an error has occurred, return it. Else return an ok status. + virtual Status status() const = 0; + + // Clients are allowed to register function/arg1/arg2 triples that + // will be invoked when this iterator is destroyed. + // + // Note that unlike all of the preceding methods, this method is + // not abstract and therefore clients should not override it. + typedef void (*CleanupFunction)(void* arg1, void* arg2); + void RegisterCleanup(CleanupFunction function, void* arg1, void* arg2); + + private: + struct Cleanup { + CleanupFunction function; + void* arg1; + void* arg2; + Cleanup* next; + }; + Cleanup cleanup_; + + // No copying allowed + Iterator(const Iterator&); + void operator=(const Iterator&); +}; + +// Return an empty iterator (yields nothing). +extern Iterator* NewEmptyIterator(); + +// Return an empty iterator with the specified status. +extern Iterator* NewErrorIterator(const Status& status); + +} // namespace table +} // namespace tensorflow + +#endif // TENSORFLOW_LIB_IO_ITERATOR_H_ |