Code for locating triples in an existing index

This is the first part of a series of PRs split of from the large
proof-of-concept PR #916,
which realizes SPARQL 1.1 Update

src/global/IdTriple.h

@@ -0,0 +1,18 @@
+// Copyright 2023, University of Freiburg
+// Chair of Algorithms and Data Structures
+// Authors: Hannah Bast <[email protected]>
+
+#pragma once
+
+#include <array>
+
+#include "global/Id.h"
+
+// Should we have an own class for this? We need this at several places.
+using IdTriple = std::array<Id, 3>;
+
+// Hash value for such triple.
+template <typename H>
+H AbslHashValue(H h, const IdTriple& triple) {
+  return H::combine(std::move(h), triple[0], triple[1], triple[2]);
+}

src/index/CMakeLists.txt

@@ -8,6 +8,7 @@ add_library(index
         VocabularyOnDisk.h VocabularyOnDisk.cpp
         IndexMetaData.h IndexMetaDataImpl.h
         MetaDataHandler.h
+        LocatedTriples.h LocatedTriples.cpp
         StxxlSortFunctors.h
         TextMetaData.cpp TextMetaData.h
         DocsDB.cpp DocsDB.h

src/index/CompressedRelation.h

@@ -305,6 +305,7 @@ class CompressedRelationReader {
   static void decompressColumn(const std::vector<char>& compressedColumn,
                                size_t numRowsToRead, Iterator iterator);
 
+ public:
   // Read the block that is identified by the `blockMetaData` from the `file`,
   // decompress and return it.
   // If `columnIndices` is `nullopt`, then all columns of the block are read,

src/index/IndexMetaData.h

@@ -1,6 +1,7 @@
 // Copyright 2015, University of Freiburg,
 // Chair of Algorithms and Data Structures.
 // Author: Björn Buchhold ([email protected])
+
 #pragma once
 
 #include <stdio.h>
@@ -13,14 +14,14 @@
 #include <utility>
 #include <vector>
 
-#include "../global/Id.h"
-#include "../util/File.h"
-#include "../util/HashMap.h"
-#include "../util/MmapVector.h"
-#include "../util/ReadableNumberFact.h"
-#include "../util/Serializer/Serializer.h"
-#include "./MetaDataHandler.h"
-#include "CompressedRelation.h"
+#include "global/Id.h"
+#include "index/CompressedRelation.h"
+#include "index/MetaDataHandler.h"
+#include "util/File.h"
+#include "util/HashMap.h"
+#include "util/MmapVector.h"
+#include "util/ReadableNumberFact.h"
+#include "util/Serializer/Serializer.h"
 
 using std::array;
 using std::pair;
@@ -86,7 +87,10 @@ class IndexMetaData {
   // name and the variable name are terrible.
 
   // For each relation, its meta data.
+ public:
   MapType _data;
+
+ private:
   // For each compressed block, its meta data.
   BlocksType _blockData;