fulltext: replace plain pointer by std::unique_ptr<>

This was a plain pointer owing to C compatibility.

Replacing it by a unique_ptr<> allows us to make it
'self-desctruct' in the constructor. However, we do this
with a special twist: the data is _not_ copied when copying
the dive, since the copied dive is not registered in the fulltext
system. Hackish, but it should(!) work.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

core/dive.cpp

@@ -49,13 +49,9 @@ dive::dive() : dcs(1)
 	id = dive_getUniqID();
 }
 
-dive::~dive()
-{
-	fulltext_unregister(this);	// TODO: this is a layering violation. Remove.
-}
-
 dive::dive(dive &&) = default;
 dive &dive::operator=(const dive &) = default;
+dive::~dive() = default;
 
 /*
  * The legacy format for sample pressures has a single pressure
@@ -180,9 +176,7 @@ void clear_dive(struct dive *d)
 void copy_dive(const struct dive *s, struct dive *d)
 {
 	/* simply copy things over, but then clear fulltext cache and dive cache. */
-	fulltext_unregister(d);
 	*d = *s;
-	d->full_text = NULL;
 	invalidate_dive_cache(d);
 }
 

core/dive.h

@@ -10,6 +10,7 @@
 #include "picture.h" // TODO: remove
 #include "tag.h"
 
+#include <memory>
 #include <string>
 #include <vector>
 
@@ -25,6 +26,19 @@ struct full_text_cache;
 struct event;
 struct trip_table;
 
+/* A unique_ptr that will not be copied if the parent class is copied.
+ * This is used to keep a pointer to the fulltext cache and avoid
+ * having it copied when the dive is copied, since the new dive is
+ * not (yet) registered in the fulltext system. Quite hackish.
+ */
+template<typename T>
+struct non_copying_unique_ptr : public std::unique_ptr<T> {
+	using std::unique_ptr<T>::unique_ptr;
+	using std::unique_ptr<T>::operator=;
+	non_copying_unique_ptr(const non_copying_unique_ptr<T> &) { }
+	void operator=(const non_copying_unique_ptr<T> &) { }
+};
+
 struct dive {
 	struct dive_trip *divetrip = nullptr;
 	timestamp_t when = 0;
@@ -55,7 +69,7 @@ struct dive {
 	bool notrip = false; /* Don't autogroup this dive to a trip */
 	bool selected = false;
 	bool hidden_by_filter = false;
-	struct full_text_cache *full_text = nullptr; /* word cache for full text search */
+	non_copying_unique_ptr<full_text_cache> full_text; /* word cache for full text search */
 	bool invalid = false;
 
 	dive();

core/fulltext.cpp

@@ -10,11 +10,6 @@
 #include <QLocale>
 #include <map>
 
-// This class caches each dives words, so that we can unregister a dive from the full text search
-struct full_text_cache {
-	std::vector<QString> words;
-};
-
 // The FullText-search class
 class FullText {
 	std::map<QString, std::vector<dive *>> words; // Dives that belong to each word
@@ -160,7 +155,7 @@ void FullText::registerDive(struct dive *d)
 	if (d->full_text)
 		unregisterWords(d, d->full_text->words);
 	else
-		d->full_text = new full_text_cache;
+		d->full_text = std::make_unique<full_text_cache>();
 	d->full_text->words = getWords(d);
 	registerWords(d, d->full_text->words);
 }
@@ -170,18 +165,15 @@ void FullText::unregisterDive(struct dive *d)
 	if (!d->full_text)
 		return;
 	unregisterWords(d, d->full_text->words);
-	delete d->full_text;
-	d->full_text = nullptr;
+	d->full_text.reset();
 }
 
 void FullText::unregisterAll()
 {
 	int i;
 	dive *d;
-	for_each_dive(i, d) {
-		delete d->full_text;
-		d->full_text = nullptr;
-	}
+	for_each_dive(i, d)
+		d->full_text.reset();
 	words.clear();
 }
 

core/fulltext.h

@@ -5,11 +5,6 @@
 // issues such as COW semantics and UTF-16 encoding, it provides
 // platform independence and reasonable performance. Therefore,
 // this is based in QString instead of std::string.
-//
-// To make this accessible from C, this does manual memory management:
-// Every dive is associated with a cache of words. Thus, when deleting
-// a dive, a function freeing that data has to be called.
-// TODO: remove this complexity.
 
 #ifndef FULLTEXT_H
 #define FULLTEXT_H
@@ -17,7 +12,6 @@
 #include <QString>
 #include <vector>
 
-struct full_text_cache;
 struct dive;
 void fulltext_register(struct dive *d); // Note: can be called repeatedly
 void fulltext_unregister(struct dive *d); // Note: can be called repeatedly
@@ -30,6 +24,11 @@ enum class StringFilterMode {
 	EXACT = 2
 };
 
+// This class caches each dives words, so that we can unregister a dive from the full text search
+struct full_text_cache {
+	std::vector<QString> words;
+};
+
 // A fulltext query. Basically a list of normalized words we search for
 struct FullTextQuery {
 	std::vector<QString> words;