QAbstractFileEngineIterator: add `bool advance()` virtual method

And remove hasNext/next() methods. This remodels QAFEI to be like
QFileSystemIterator. This better fits the logic in the newly added
QDirListing class (which uses STL-style iterators).

QFSFileEngineIterator:
Initialize the internal nativeIterator in the constructor; also replace
the advance() private method with an override for the advance() method
inherited from the base class.

QResourceFileEngineIterator:
Override currentFileInfo(), with a QResouces the QFileInfo is created
on demand if/when this method is called.

This is the backend/private API, and QDirListing is the public API that
can be used in a ranged-for to iterate over directory entries.

Change-Id: I93eb7bdd64823ac01eea2dcaaa6bcc8ad868b2c4
Reviewed-by: Assam Boudjelthia <assam.boudjelthia@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

4 files changed, 27 insertions, 43 deletions

diff --git a/src/plugins/platforms/android/androidcontentfileengine.cpp b/src/plugins/platforms/android/androidcontentfileengine.cpp
index 67221080b2..d0a22e35ab 100644
--- a/src/plugins/platforms/android/androidcontentfileengine.cpp
+++ b/src/plugins/platforms/android/androidcontentfileengine.cpp
@@ -276,15 +276,7 @@ AndroidContentFileEngineIterator::~AndroidContentFileEngineIterator()
 {
 }
 
-QString AndroidContentFileEngineIterator::next()
-{
-    if (!hasNext())
-        return QString();
-    ++m_index;
-    return currentFilePath();
-}
-
-bool AndroidContentFileEngineIterator::hasNext() const
+bool AndroidContentFileEngineIterator::advance()
 {
     if (m_index == -1 && m_files.isEmpty()) {
         const auto currentPath = path();
@@ -295,9 +287,18 @@ bool AndroidContentFileEngineIterator::hasNext() const
         if (iterDoc->isDirectory())
             for (const auto &doc : iterDoc->listFiles())
                 m_files.append(doc);
+        if (m_files.isEmpty())
+            return false;
+        m_index = 0;
+        return true;
     }
 
-    return m_index < (m_files.size() - 1);
+    if (m_index < m_files.size() - 1) {
+        ++m_index;
+        return true;
+    }
+
+    return false;
 }
 
 QString AndroidContentFileEngineIterator::currentFileName() const
diff --git a/src/plugins/platforms/android/androidcontentfileengine.h b/src/plugins/platforms/android/androidcontentfileengine.h
index dd7985db80..ee43185eab 100644
--- a/src/plugins/platforms/android/androidcontentfileengine.h
+++ b/src/plugins/platforms/android/androidcontentfileengine.h
@@ -55,8 +55,9 @@ public:
     AndroidContentFileEngineIterator(const QString &path, QDir::Filters filters,
                                      const QStringList &filterNames);
     ~AndroidContentFileEngineIterator();
-    QString next() override;
-    bool hasNext() const override;
+
+    bool advance() override;
+
     QString currentFileName() const override;
     QString currentFilePath() const override;
 private:
diff --git a/src/plugins/platforms/android/qandroidassetsfileenginehandler.cpp b/src/plugins/platforms/android/qandroidassetsfileenginehandler.cpp
index 20ce0b5710..d85efdd773 100644
--- a/src/plugins/platforms/android/qandroidassetsfileenginehandler.cpp
+++ b/src/plugins/platforms/android/qandroidassetsfileenginehandler.cpp
@@ -142,17 +142,13 @@ public:
         return m_path + at(m_index).name;
     }
 
-    bool hasNext() const
+    bool advance()
     {
-        return !empty() && m_index + 1 < size();
-    }
-
-    std::optional<std::pair<QString, AssetItem>> next()
-    {
-        if (!hasNext())
-            return {};
-        ++m_index;
-        return std::pair<QString, AssetItem>(currentFileName(), at(m_index));
+        if (!empty() && m_index + 1 < size()) {
+            ++m_index;
+            return true;
+        }
+        return false;
     }
 
 private:
@@ -195,21 +191,9 @@ public:
         return m_currentIterator->currentFilePath();
     }
 
-    bool hasNext() const override
+    bool advance() override
     {
-        if (!m_currentIterator)
-            return false;
-        return m_currentIterator->hasNext();
-    }
-
-    QString next() override
-    {
-        if (!m_currentIterator)
-            return {};
-        auto res = m_currentIterator->next();
-        if (!res)
-            return {};
-        return res->first;
+        return m_currentIterator ? m_currentIterator->advance() : false;
     }
 
 private:
diff --git a/src/plugins/platforms/ios/optional/nsphotolibrarysupport/qiosfileengineassetslibrary.mm b/src/plugins/platforms/ios/optional/nsphotolibrarysupport/qiosfileengineassetslibrary.mm
index 87cc6d5bea..f7e112ab81 100644
--- a/src/plugins/platforms/ios/optional/nsphotolibrarysupport/qiosfileengineassetslibrary.mm
+++ b/src/plugins/platforms/ios/optional/nsphotolibrarysupport/qiosfileengineassetslibrary.mm
@@ -270,8 +270,11 @@ public:
         g_iteratorCurrentUrl.setLocalData(QString());
     }
 
-    QString next() override
+    bool advance() override
     {
+        if (!m_enumerator->hasNext())
+            return false;
+
         // Cache the URL that we are about to return, since QDir will immediately create a
         // new file engine on the file and ask if it exists. Unless we do this, we end up
         // creating a new ALAsset just to verify its existence, which will be especially
@@ -279,12 +282,7 @@ public:
         ALAsset *asset = m_enumerator->next();
         QString url = QUrl::fromNSURL([asset valueForProperty:ALAssetPropertyAssetURL]).toString();
         g_iteratorCurrentUrl.setLocalData(url);
-        return url;
-    }
-
-    bool hasNext() const override
-    {
-        return m_enumerator->hasNext();
+        return true;
     }
 
     QString currentFileName() const override