Use std::optional to represent "any value" filters

PR #16460.

src/base/torrentfilter.cpp

@@ -31,9 +31,9 @@
 #include "bittorrent/infohash.h"
 #include "bittorrent/torrent.h"
 
-const QString TorrentFilter::AnyCategory;
+const std::optional<QString> TorrentFilter::AnyCategory;
-const TorrentIDSet TorrentFilter::AnyID {{}};
+const std::optional<TorrentIDSet> TorrentFilter::AnyID;
-const QString TorrentFilter::AnyTag;
+const std::optional<QString> TorrentFilter::AnyTag;
 
 const TorrentFilter TorrentFilter::DownloadingTorrent(TorrentFilter::Downloading);
 const TorrentFilter TorrentFilter::SeedingTorrent(TorrentFilter::Seeding);
@@ -50,7 +50,8 @@ const TorrentFilter TorrentFilter::ErroredTorrent(TorrentFilter::Errored);
 
 using BitTorrent::Torrent;
 
-TorrentFilter::TorrentFilter(const Type type, const TorrentIDSet &idSet, const QString &category, const QString &tag)
+TorrentFilter::TorrentFilter(const Type type, const std::optional<TorrentIDSet> &idSet
+                             , const std::optional<QString> &category, const std::optional<QString> &tag)
     : m_type(type)
     , m_category(category)
     , m_tag(tag)
@@ -58,7 +59,8 @@ TorrentFilter::TorrentFilter(const Type type, const TorrentIDSet &idSet, const Q
 {
 }
 
-TorrentFilter::TorrentFilter(const QString &filter, const TorrentIDSet &idSet, const QString &category, const QString &tag)
+TorrentFilter::TorrentFilter(const QString &filter, const std::optional<TorrentIDSet> &idSet
+                             , const std::optional<QString> &category, const std::optional<QString> &tag)
     : m_type(All)
     , m_category(category)
     , m_tag(tag)
@@ -110,7 +112,7 @@ bool TorrentFilter::setTypeByName(const QString &filter)
     return setType(type);
 }
 
-bool TorrentFilter::setTorrentIDSet(const TorrentIDSet &idSet)
+bool TorrentFilter::setTorrentIDSet(const std::optional<TorrentIDSet> &idSet)
 {
     if (m_idSet != idSet)
     {
@@ -121,12 +123,9 @@ bool TorrentFilter::setTorrentIDSet(const TorrentIDSet &idSet)
     return false;
 }
 
-bool TorrentFilter::setCategory(const QString &category)
+bool TorrentFilter::setCategory(const std::optional<QString> &category)
 {
-    // QString::operator==() doesn't distinguish between empty and null strings.
+    if (m_category != category)
-    if ((m_category != category)
-            || (m_category.isNull() && !category.isNull())
-            || (!m_category.isNull() && category.isNull()))
     {
         m_category = category;
         return true;
@@ -135,12 +134,9 @@ bool TorrentFilter::setCategory(const QString &category)
     return false;
 }
 
-bool TorrentFilter::setTag(const QString &tag)
+bool TorrentFilter::setTag(const std::optional<QString> &tag)
 {
-    // QString::operator==() doesn't distinguish between empty and null strings.
+    if (m_tag != tag)
-    if ((m_tag != tag)
-        || (m_tag.isNull() && !tag.isNull())
-        || (!m_tag.isNull() && tag.isNull()))
     {
         m_tag = tag;
         return true;
@@ -196,23 +192,28 @@ bool TorrentFilter::matchState(const BitTorrent::Torrent *const torrent) const
 
 bool TorrentFilter::matchHash(const BitTorrent::Torrent *const torrent) const
 {
-    if (m_idSet == AnyID) return true;
+    if (!m_idSet)
+        return true;
 
-    return m_idSet.contains(torrent->id());
+    return m_idSet->contains(torrent->id());
 }
 
 bool TorrentFilter::matchCategory(const BitTorrent::Torrent *const torrent) const
 {
-    if (m_category.isNull()) return true;
+    if (!m_category)
+        return true;
 
-    return (torrent->belongsToCategory(m_category));
+    return (torrent->belongsToCategory(*m_category));
 }
 
 bool TorrentFilter::matchTag(const BitTorrent::Torrent *const torrent) const
 {
-    // Empty tag is a special value to indicate we're filtering for untagged torrents.
+    if (!m_tag)
-    if (m_tag.isNull()) return true;
+        return true;
-    if (m_tag.isEmpty()) return torrent->tags().isEmpty();
 
-    return (torrent->hasTag(m_tag));
+    // Empty tag is a special value to indicate we're filtering for untagged torrents.
+    if (m_tag->isEmpty())
+        return torrent->tags().isEmpty();
+
+    return torrent->hasTag(*m_tag);
 }

src/base/torrentfilter.h

@@ -28,6 +28,8 @@
 
 #pragma once
 
+#include <optional>
+
 #include <QSet>
 #include <QString>
 
@@ -61,9 +63,9 @@ public:
     };
 
     // These mean any permutation, including no category / tag.
-    static const QString AnyCategory;
+    static const std::optional<QString> AnyCategory;
-    static const TorrentIDSet AnyID;
+    static const std::optional<TorrentIDSet> AnyID;
-    static const QString AnyTag;
+    static const std::optional<QString> AnyTag;
 
     static const TorrentFilter DownloadingTorrent;
     static const TorrentFilter SeedingTorrent;
@@ -80,15 +82,16 @@ public:
 
     TorrentFilter() = default;
     // category & tags: pass empty string for uncategorized / untagged torrents.
-    // Pass null string (QString()) to disable filtering (i.e. all torrents).
+    TorrentFilter(Type type, const std::optional<TorrentIDSet> &idSet = AnyID
-    TorrentFilter(Type type, const TorrentIDSet &idSet = AnyID, const QString &category = AnyCategory, const QString &tag = AnyTag);
+            , const std::optional<QString> &category = AnyCategory, const std::optional<QString> &tag = AnyTag);
-    TorrentFilter(const QString &filter, const TorrentIDSet &idSet = AnyID, const QString &category = AnyCategory, const QString &tags = AnyTag);
+    TorrentFilter(const QString &filter, const std::optional<TorrentIDSet> &idSet = AnyID
+            , const std::optional<QString> &category = AnyCategory, const std::optional<QString> &tags = AnyTag);
 
     bool setType(Type type);
     bool setTypeByName(const QString &filter);
-    bool setTorrentIDSet(const TorrentIDSet &idSet);
+    bool setTorrentIDSet(const std::optional<TorrentIDSet> &idSet);
-    bool setCategory(const QString &category);
+    bool setCategory(const std::optional<QString> &category);
-    bool setTag(const QString &tag);
+    bool setTag(const std::optional<QString> &tag);
 
     bool match(const BitTorrent::Torrent *torrent) const;
 
@@ -99,7 +102,7 @@ private:
     bool matchTag(const BitTorrent::Torrent *torrent) const;
 
     Type m_type {All};
-    QString m_category;
+    std::optional<QString> m_category;
-    QString m_tag;
+    std::optional<QString> m_tag;
-    TorrentIDSet m_idSet;
+    std::optional<TorrentIDSet> m_idSet;
 };

src/webui/api/torrentscontroller.cpp

@@ -140,6 +140,15 @@ namespace
         }
     }
 
+    std::optional<QString> getOptionalString(const StringMap &params, const QString &name)
+    {
+        const auto it = params.constFind(name);
+        if (it == params.cend())
+            return std::nullopt;
+
+        return it.value();
+    }
+
     QJsonArray getStickyTrackers(const BitTorrent::Torrent *const torrent)
     {
         int seedsDHT = 0, seedsPeX = 0, seedsLSD = 0, leechesDHT = 0, leechesPeX = 0, leechesLSD = 0;
@@ -255,19 +264,23 @@ namespace
 void TorrentsController::infoAction()
 {
     const QString filter {params()["filter"]};
-    const QString category {params()["category"]};
+    const std::optional<QString> category = getOptionalString(params(), QLatin1String("category"));
-    const QString tag {params()["tag"]};
+    const std::optional<QString> tag = getOptionalString(params(), QLatin1String("tag"));
     const QString sortedColumn {params()["sort"]};
     const bool reverse {parseBool(params()["reverse"]).value_or(false)};
     int limit {params()["limit"].toInt()};
     int offset {params()["offset"].toInt()};
     const QStringList hashes {params()["hashes"].split('|', Qt::SkipEmptyParts)};
 
-    TorrentIDSet idSet;
+    std::optional<TorrentIDSet> idSet;
-    for (const QString &hash : hashes)
+    if (!hashes.isEmpty())
-        idSet.insert(BitTorrent::TorrentID::fromString(hash));
+    {
+        idSet = TorrentIDSet();
+        for (const QString &hash : hashes)
+            idSet->insert(BitTorrent::TorrentID::fromString(hash));
+    }
 
-    const TorrentFilter torrentFilter(filter, (hashes.isEmpty() ? TorrentFilter::AnyID : idSet), category, tag);
+    const TorrentFilter torrentFilter {filter, idSet, category, tag};
     QVariantList torrentList;
     for (const BitTorrent::Torrent *torrent : asConst(BitTorrent::Session::instance()->torrents()))
     {