shiboken: Introduce DefaultValue

Introduce a small class storing the return value of
Generator::minimalConstructor() consisting of a type enumeration and a
value, offering formatting for the use cases variable initializations,
return values and constructor arguments lists.
Having distinct formatting for the different use cases has some
advantages:
- Can use nullptr without casts (except in constructor arguments
  lists, where the type is needed for disambiguation).
- In the previous implementation using a string, "" indicated an
  error; so, it was not possible to use it for default-constructors.
  It is now possible to handle default-constructors for
  initialization ("Foo f" instead of "Foo f = Foo()".
- Can use {} for return values.

Task-number: PYSIDE-62
Change-Id: I73229cb957d4b92b43de4cdbc3c66703f48faa61
Reviewed-by: Christian Tismer <tismer@stackless.com>

1 files changed, 18 insertions, 11 deletions

diff --git a/sources/shiboken2/generator/shiboken2/shibokengenerator.cpp b/sources/shiboken2/generator/shiboken2/shibokengenerator.cpp
index 6a7cef6ef..6d263dd01 100644
--- a/sources/shiboken2/generator/shiboken2/shibokengenerator.cpp
+++ b/sources/shiboken2/generator/shiboken2/shibokengenerator.cpp
@@ -2653,30 +2653,37 @@ QString  ShibokenGenerator::getDefaultValue(const AbstractMetaFunction* func, co
 
 void ShibokenGenerator::writeMinimalConstructorExpression(QTextStream& s, const AbstractMetaType* type, const QString& defaultCtor)
 {
-    if (defaultCtor.isEmpty() && isCppPrimitive(type))
+    if (!defaultCtor.isEmpty()) {
+         s << " = " << defaultCtor;
+         return;
+    }
+    if (isCppPrimitive(type))
         return;
-    QString ctor = defaultCtor.isEmpty() ? minimalConstructor(type) : defaultCtor;
-    if (ctor.isEmpty()) {
+    const auto ctor = minimalConstructor(type);
+    if (ctor.isValid()) {
+        s << ctor.initialization();
+    } else {
         const QString message = msgCouldNotFindMinimalConstructor(QLatin1String(__FUNCTION__), type->cppSignature());
         qCWarning(lcShiboken()).noquote() << message;
         s << ";\n#error " << message << '\n';
-    } else {
-        s << " = " << ctor;
     }
 }
 
 void ShibokenGenerator::writeMinimalConstructorExpression(QTextStream& s, const TypeEntry* type, const QString& defaultCtor)
 {
-    if (defaultCtor.isEmpty() && isCppPrimitive(type))
+    if (!defaultCtor.isEmpty()) {
+         s << " = " << defaultCtor;
+         return;
+    }
+    if (isCppPrimitive(type))
         return;
-    QString ctor = defaultCtor.isEmpty() ? minimalConstructor(type) : defaultCtor;
-
-    if (ctor.isEmpty()) {
+    const auto ctor = minimalConstructor(type);
+    if (ctor.isValid()) {
+        s << ctor.initialization();
+    } else {
         const QString message = msgCouldNotFindMinimalConstructor(QLatin1String(__FUNCTION__), type->qualifiedCppName());
         qCWarning(lcShiboken()).noquote() << message;
         s << ";\n#error " << message << endl;
-    } else {
-        s << " = " << ctor;
     }
 }