Eliminate duplicate overrides of Converter methods in example

The Out-only converters shouldn't need to implement loadFile(), as it
shouldn't be called - a converter is not used for input unless it says
it supports input. At the same time, provide the "ground state"
implementations for optionsHelp(), outputOptions() and probeFile() to
save the trivial implementations the need to duplicate one another.

In the process, make the handling of loadFile()'s outputConverter more
consistent among those that do implement it.  Always set
outputConverter if it's initially null (the caller does assert this).

Pick-to: 6.6 6.5
Task-number: QTBUG-111228
Change-Id: I856d12c791d1f8e0accdb7dd1412d493117b2302
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

12 files changed, 21 insertions, 82 deletions

diff --git a/examples/corelib/serialization/convert/cborconverter.cpp b/examples/corelib/serialization/convert/cborconverter.cpp
index 4ee86535aa..21f63f7d83 100644
--- a/examples/corelib/serialization/convert/cborconverter.cpp
+++ b/examples/corelib/serialization/convert/cborconverter.cpp
@@ -142,20 +142,6 @@ const char *CborDiagnosticDumper::optionsHelp() const
     return diagnosticHelp;
 }
 
-bool CborDiagnosticDumper::probeFile(QIODevice *f) const
-{
-    Q_UNUSED(f);
-    return false;
-}
-
-QVariant CborDiagnosticDumper::loadFile(QIODevice *f, const Converter *&outputConverter) const
-{
-    Q_UNREACHABLE();
-    Q_UNUSED(f);
-    Q_UNUSED(outputConverter);
-    return QVariant();
-}
-
 void CborDiagnosticDumper::saveFile(QIODevice *f, const QVariant &contents,
                                     const QStringList &options) const
 {
diff --git a/examples/corelib/serialization/convert/cborconverter.h b/examples/corelib/serialization/convert/cborconverter.h
index ff03185656..db68f99fda 100644
--- a/examples/corelib/serialization/convert/cborconverter.h
+++ b/examples/corelib/serialization/convert/cborconverter.h
@@ -14,8 +14,6 @@ public:
     Directions directions() const override;
     Options outputOptions() const override;
     const char *optionsHelp() const override;
-    bool probeFile(QIODevice *f) const override;
-    QVariant loadFile(QIODevice *f, const Converter *&outputConverter) const override;
     void saveFile(QIODevice *f, const QVariant &contents,
                   const QStringList &options) const override;
 };
diff --git a/examples/corelib/serialization/convert/converter.cpp b/examples/corelib/serialization/convert/converter.cpp
index 7ecd4134e9..231d0d51cd 100644
--- a/examples/corelib/serialization/convert/converter.cpp
+++ b/examples/corelib/serialization/convert/converter.cpp
@@ -23,3 +23,20 @@ const QList<const Converter *> &Converter::allConverters()
 {
     return converters();
 }
+
+// Some virtual methods that Converter classes needn't override, when not relevant:
+Converter::Options Converter::outputOptions() const { return {}; }
+const char *Converter::optionsHelp() const { return nullptr; }
+bool Converter::probeFile(QIODevice *) const { return false; }
+
+// The virtual method they should override if they claim to support In:
+QVariant Converter::loadFile(QIODevice *, const Converter *&outputConverter) const
+{
+    Q_ASSERT(!directions().testFlag(Converter::Direction::In));
+    // For those that don't, this should never be called.
+    Q_UNIMPLEMENTED();
+    // But every implementation should at least do this:
+    if (!outputConverter)
+        outputConverter = this;
+    return QVariant();
+}
diff --git a/examples/corelib/serialization/convert/converter.h b/examples/corelib/serialization/convert/converter.h
index fabbffddfb..6631d3107f 100644
--- a/examples/corelib/serialization/convert/converter.h
+++ b/examples/corelib/serialization/convert/converter.h
@@ -29,10 +29,10 @@ public:
 
     virtual QString name() const = 0;
     virtual Directions directions() const = 0;
-    virtual Options outputOptions() const = 0;
-    virtual const char *optionsHelp() const = 0;
-    virtual bool probeFile(QIODevice *f) const = 0;
-    virtual QVariant loadFile(QIODevice *f, const Converter *&outputConverter) const = 0;
+    virtual Options outputOptions() const;
+    virtual const char *optionsHelp() const;
+    virtual bool probeFile(QIODevice *f) const;
+    virtual QVariant loadFile(QIODevice *f, const Converter *&outputConverter) const;
     virtual void saveFile(QIODevice *f, const QVariant &contents,
                           const QStringList &options) const = 0;
 };
diff --git a/examples/corelib/serialization/convert/debugtextdumper.cpp b/examples/corelib/serialization/convert/debugtextdumper.cpp
index 2415e32f44..f010bd8e2a 100644
--- a/examples/corelib/serialization/convert/debugtextdumper.cpp
+++ b/examples/corelib/serialization/convert/debugtextdumper.cpp
@@ -59,25 +59,6 @@ Converter::Options DebugTextDumper::outputOptions() const
     return SupportsArbitraryMapKeys;
 }
 
-const char *DebugTextDumper::optionsHelp() const
-{
-    return nullptr;
-}
-
-bool DebugTextDumper::probeFile(QIODevice *f) const
-{
-    Q_UNUSED(f);
-    return false;
-}
-
-QVariant DebugTextDumper::loadFile(QIODevice *f, const Converter *&outputConverter) const
-{
-    Q_UNREACHABLE();
-    Q_UNUSED(f);
-    Q_UNUSED(outputConverter);
-    return QVariant();
-}
-
 void DebugTextDumper::saveFile(QIODevice *f, const QVariant &contents,
                                const QStringList &options) const
 {
diff --git a/examples/corelib/serialization/convert/debugtextdumper.h b/examples/corelib/serialization/convert/debugtextdumper.h
index 636e6ccb3d..7d3d762104 100644
--- a/examples/corelib/serialization/convert/debugtextdumper.h
+++ b/examples/corelib/serialization/convert/debugtextdumper.h
@@ -13,9 +13,6 @@ public:
     QString name() const override;
     Directions directions() const override;
     Options outputOptions() const override;
-    const char *optionsHelp() const override;
-    bool probeFile(QIODevice *f) const override;
-    QVariant loadFile(QIODevice *f, const Converter *&outputConverter) const override;
     void saveFile(QIODevice *f, const QVariant &contents,
                   const QStringList &options) const override;
 };
diff --git a/examples/corelib/serialization/convert/jsonconverter.cpp b/examples/corelib/serialization/convert/jsonconverter.cpp
index 611061705b..1b59ed5c1f 100644
--- a/examples/corelib/serialization/convert/jsonconverter.cpp
+++ b/examples/corelib/serialization/convert/jsonconverter.cpp
@@ -33,11 +33,6 @@ Converter::Directions JsonConverter::directions() const
     return Direction::InOut;
 }
 
-Converter::Options JsonConverter::outputOptions() const
-{
-    return {};
-}
-
 const char *JsonConverter::optionsHelp() const
 {
     return jsonOptionHelp;
diff --git a/examples/corelib/serialization/convert/jsonconverter.h b/examples/corelib/serialization/convert/jsonconverter.h
index acff1433be..e1dd1ecdb4 100644
--- a/examples/corelib/serialization/convert/jsonconverter.h
+++ b/examples/corelib/serialization/convert/jsonconverter.h
@@ -12,7 +12,6 @@ class JsonConverter : public Converter
 public:
     QString name() const override;
     Directions directions() const override;
-    Options outputOptions() const override;
     const char *optionsHelp() const override;
     bool probeFile(QIODevice *f) const override;
     QVariant loadFile(QIODevice *f, const Converter *&outputConverter) const override;
diff --git a/examples/corelib/serialization/convert/nullconverter.cpp b/examples/corelib/serialization/convert/nullconverter.cpp
index 00ae47a086..fb8be5c944 100644
--- a/examples/corelib/serialization/convert/nullconverter.cpp
+++ b/examples/corelib/serialization/convert/nullconverter.cpp
@@ -26,25 +26,6 @@ Converter::Options NullConverter::outputOptions() const
     return SupportsArbitraryMapKeys;
 }
 
-const char *NullConverter::optionsHelp() const
-{
-    return nullptr;
-}
-
-bool NullConverter::probeFile(QIODevice *f) const
-{
-    Q_UNUSED(f);
-    return false;
-}
-
-QVariant NullConverter::loadFile(QIODevice *f, const Converter *&outputConverter) const
-{
-    Q_UNUSED(f);
-    Q_UNUSED(outputConverter);
-    outputConverter = this;
-    return QVariant();
-}
-
 void NullConverter::saveFile(QIODevice *f, const QVariant &contents,
                              const QStringList &options) const
 {
diff --git a/examples/corelib/serialization/convert/nullconverter.h b/examples/corelib/serialization/convert/nullconverter.h
index fb215c313c..1bdf9f22f7 100644
--- a/examples/corelib/serialization/convert/nullconverter.h
+++ b/examples/corelib/serialization/convert/nullconverter.h
@@ -13,9 +13,6 @@ public:
     QString name() const override;
     Directions directions() const override;
     Options outputOptions() const override;
-    const char *optionsHelp() const override;
-    bool probeFile(QIODevice *f) const override;
-    QVariant loadFile(QIODevice *f, const Converter *&outputConverter) const override;
     void saveFile(QIODevice *f, const QVariant &contents,
                   const QStringList &options) const override;
 };
diff --git a/examples/corelib/serialization/convert/textconverter.cpp b/examples/corelib/serialization/convert/textconverter.cpp
index 3bfd806bf4..1f8b4f9c19 100644
--- a/examples/corelib/serialization/convert/textconverter.cpp
+++ b/examples/corelib/serialization/convert/textconverter.cpp
@@ -54,16 +54,6 @@ Converter::Directions TextConverter::directions() const
     return Direction::InOut;
 }
 
-Converter::Options TextConverter::outputOptions() const
-{
-    return {};
-}
-
-const char *TextConverter::optionsHelp() const
-{
-    return nullptr;
-}
-
 bool TextConverter::probeFile(QIODevice *f) const
 {
     if (QFile *file = qobject_cast<QFile *>(f))
diff --git a/examples/corelib/serialization/convert/textconverter.h b/examples/corelib/serialization/convert/textconverter.h
index 46e5500d9a..526f295517 100644
--- a/examples/corelib/serialization/convert/textconverter.h
+++ b/examples/corelib/serialization/convert/textconverter.h
@@ -12,8 +12,6 @@ class TextConverter : public Converter
 public:
     QString name() const override;
     Directions directions() const override;
-    Options outputOptions() const override;
-    const char *optionsHelp() const override;
     bool probeFile(QIODevice *f) const override;
     QVariant loadFile(QIODevice *f, const Converter *&outputConverter) const override;
     void saveFile(QIODevice *f, const QVariant &contents,