Port over Icing c++ code from upstream

Change-Id: Ia3981fed7e0e70589efc027d4123f306cdfbe990

1 files changed, 99 insertions, 0 deletions

diff --git a/icing/index/iterator/doc-hit-info-iterator.h b/icing/index/iterator/doc-hit-info-iterator.h
new file mode 100644
index 0000000..eace911
--- /dev/null
+++ b/icing/index/iterator/doc-hit-info-iterator.h
@@ -0,0 +1,99 @@
+// Copyright (C) 2019 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ICING_INDEX_ITERATOR_DOC_HIT_INFO_ITERATOR_H_
+#define ICING_INDEX_ITERATOR_DOC_HIT_INFO_ITERATOR_H_
+
+#include <cstdint>
+#include <string>
+
+#include "utils/base/status.h"
+#include "utils/base/statusor.h"
+#include "icing/absl_ports/canonical_errors.h"
+#include "icing/index/hit/doc-hit-info.h"
+#include "icing/schema/section.h"
+#include "icing/store/document-id.h"
+
+namespace icing {
+namespace lib {
+
+// Iterator over DocHitInfos (collapsed Hits) in REVERSE document_id order.
+//
+// NOTE: You must call Advance() before calling hit_info() or
+// hit_intersect_section_ids_mask().
+//
+// Example:
+// DocHitInfoIterator itr = GetIterator(...);
+// while (itr.Advance()) {
+//   HandleDocHitInfo(itr.hit_info());
+// }
+class DocHitInfoIterator {
+ public:
+  virtual ~DocHitInfoIterator() = default;
+
+  // Returns:
+  //   OK if was able to advance to a new document_id.
+  //   RESOUCE_EXHAUSTED if we've run out of document_ids to iterate over
+  virtual libtextclassifier3::Status Advance() = 0;
+
+  // Returns the DocHitInfo that the iterator is currently at. The DocHitInfo
+  // will have a kInvalidDocumentId if Advance() was not called after
+  // construction or if Advance returned an error.
+  const DocHitInfo& doc_hit_info() const { return doc_hit_info_; }
+
+  // SectionIdMask representing which sections (if any) have matched *ALL* query
+  // terms for the current document_id.
+  SectionIdMask hit_intersect_section_ids_mask() const {
+    return hit_intersect_section_ids_mask_;
+  }
+
+  // Gets the number of flash index blocks that have been read as a
+  // result of operations on this object.
+  virtual int32_t GetNumBlocksInspected() const = 0;
+
+  // HitIterators may be constructed into trees. Internal nodes will return the
+  // sum of the number of Advance() calls to all leaf nodes. Leaf nodes will
+  // return the number of times Advance() was called on it.
+  virtual int32_t GetNumLeafAdvanceCalls() const = 0;
+
+  // A string representing the iterator.
+  virtual std::string ToString() const = 0;
+
+ protected:
+  DocHitInfo doc_hit_info_;
+  SectionIdMask hit_intersect_section_ids_mask_ = kSectionIdMaskNone;
+
+  // Helper function to advance the given iterator to at most the given
+  // document_id.
+  libtextclassifier3::StatusOr<DocumentId> AdvanceTo(DocHitInfoIterator* it,
+                                                     DocumentId document_id) {
+    while (it->Advance().ok()) {
+      if (it->doc_hit_info().document_id() <= document_id) {
+        return it->doc_hit_info().document_id();
+      }
+    }
+
+    // Didn't find anything for the other iterator, reset to invalid values and
+    // return.
+    doc_hit_info_ = DocHitInfo(kInvalidDocumentId);
+    hit_intersect_section_ids_mask_ = kSectionIdMaskNone;
+    return absl_ports::ResourceExhaustedError(
+        "No more DocHitInfos in iterator");
+  }
+};  // namespace DocHitInfoIterator
+
+}  // namespace lib
+}  // namespace icing
+
+#endif  // ICING_INDEX_ITERATOR_DOC_HIT_INFO_ITERATOR_H_