Add QDebug support for NSObject and a few selected CoreFoundation types

Lets us print out the interface name in addition to the address when
doing:

  qDebug() << myNSObject;

Unfortunately, CFTypeRef is just a typedef to void*, so we can't add a
generic overload for CFTypeRef. For now, we provide operators for
commonly used Core Foundation and Core Graphics types. Additional
types may be added using Q_DECLARE_QDEBUG_OPERATOR_FOR_CF_TYPE.

Change-Id: I27b12ef9e62cb1be348b9771cb31657692903f6c
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

2 files changed, 110 insertions, 0 deletions

diff --git a/src/corelib/io/qdebug.h b/src/corelib/io/qdebug.h
index 2f487b8a1f..27abf2a740 100644
--- a/src/corelib/io/qdebug.h
+++ b/src/corelib/io/qdebug.h
@@ -281,6 +281,82 @@ inline QDebug operator<<(QDebug debug, const QFlags<T> &flags)
     return debug;
 }
 
+#ifdef Q_OS_MAC
+
+// We provide QDebug stream operators for commonly used Core Foundation
+// and Core Graphics types, as well as NSObject. Additional CF/CG types
+// may be added by the user, using Q_DECLARE_QDEBUG_OPERATOR_FOR_CF_TYPE.
+
+#define QT_FOR_EACH_CORE_FOUNDATION_TYPE(F) \
+    F(CFArray) \
+    F(CFURL) \
+    F(CFData) \
+    F(CFNumber) \
+    F(CFDictionary) \
+    F(CFLocale) \
+    F(CFDate) \
+    F(CFBoolean) \
+    F(CFTimeZone) \
+
+#define QT_FOR_EACH_MUTABLE_CORE_FOUNDATION_TYPE(F) \
+    F(CFError) \
+    F(CFBundle) \
+
+#define QT_FOR_EACH_CORE_GRAPHICS_TYPE(F) \
+    F(CGPath) \
+
+#define QT_FOR_EACH_MUTABLE_CORE_GRAPHICS_TYPE(F) \
+    F(CGColorSpace) \
+    F(CGImage) \
+    F(CGFont) \
+    F(CGColor) \
+
+#define QT_FORWARD_DECLARE_CF_TYPE(type) Q_FORWARD_DECLARE_CF_TYPE(type);
+#define QT_FORWARD_DECLARE_MUTABLE_CF_TYPE(type) Q_FORWARD_DECLARE_MUTABLE_CF_TYPE(type);
+#define QT_FORWARD_DECLARE_CG_TYPE(type) typedef const struct type *type ## Ref;
+#define QT_FORWARD_DECLARE_MUTABLE_CG_TYPE(type) typedef struct type *type ## Ref;
+
+QT_END_NAMESPACE
+Q_FORWARD_DECLARE_CF_TYPE(CFString);
+Q_FORWARD_DECLARE_OBJC_CLASS(NSObject);
+QT_FOR_EACH_CORE_FOUNDATION_TYPE(QT_FORWARD_DECLARE_CF_TYPE);
+QT_FOR_EACH_MUTABLE_CORE_FOUNDATION_TYPE(QT_FORWARD_DECLARE_MUTABLE_CF_TYPE);
+QT_FOR_EACH_CORE_GRAPHICS_TYPE(QT_FORWARD_DECLARE_CG_TYPE);
+QT_FOR_EACH_MUTABLE_CORE_GRAPHICS_TYPE(QT_FORWARD_DECLARE_MUTABLE_CG_TYPE);
+QT_BEGIN_NAMESPACE
+
+#define QT_FORWARD_DECLARE_QDEBUG_OPERATOR_FOR_CF_TYPE(CFType) \
+    Q_CORE_EXPORT QDebug operator<<(QDebug, CFType##Ref);
+
+#define Q_DECLARE_QDEBUG_OPERATOR_FOR_CF_TYPE(CFType) \
+    QDebug operator<<(QDebug debug, CFType##Ref ref) \
+    { \
+        if (!ref) \
+            return debug << QT_STRINGIFY(CFType) "Ref(0x0)"; \
+        if (CFStringRef description = CFCopyDescription(ref)) { \
+            QDebugStateSaver saver(debug); \
+            debug.noquote() << description; \
+            CFRelease(description); \
+        } \
+        return debug; \
+    }
+
+// Defined in qcore_mac_objc.mm
+Q_CORE_EXPORT QDebug operator<<(QDebug, const NSObject *);
+Q_CORE_EXPORT QDebug operator<<(QDebug, CFStringRef);
+
+QT_FOR_EACH_CORE_FOUNDATION_TYPE(QT_FORWARD_DECLARE_QDEBUG_OPERATOR_FOR_CF_TYPE);
+QT_FOR_EACH_MUTABLE_CORE_FOUNDATION_TYPE(QT_FORWARD_DECLARE_QDEBUG_OPERATOR_FOR_CF_TYPE);
+QT_FOR_EACH_CORE_GRAPHICS_TYPE(QT_FORWARD_DECLARE_QDEBUG_OPERATOR_FOR_CF_TYPE);
+QT_FOR_EACH_MUTABLE_CORE_GRAPHICS_TYPE(QT_FORWARD_DECLARE_QDEBUG_OPERATOR_FOR_CF_TYPE);
+
+#undef QT_FORWARD_DECLARE_CF_TYPE
+#undef QT_FORWARD_DECLARE_MUTABLE_CF_TYPE
+#undef QT_FORWARD_DECLARE_CG_TYPE
+#undef QT_FORWARD_DECLARE_MUTABLE_CG_TYPE
+
+#endif // Q_OS_MAC
+
 QT_END_NAMESPACE
 
 #endif // QDEBUG_H
diff --git a/src/corelib/kernel/qcore_mac_objc.mm b/src/corelib/kernel/qcore_mac_objc.mm
index 8ac062a154..265126dc58 100644
--- a/src/corelib/kernel/qcore_mac_objc.mm
+++ b/src/corelib/kernel/qcore_mac_objc.mm
@@ -42,6 +42,8 @@
 
 #include <private/qcore_mac_p.h>
 
+#include <qdebug.h>
+
 #ifdef Q_OS_IOS
 #import <UIKit/UIKit.h>
 #endif
@@ -61,6 +63,38 @@ QString QCFString::toQString(const NSString *nsstr)
     return toQString(reinterpret_cast<CFStringRef>(nsstr));
 }
 
+// -------------------------------------------------------------------------
+
+QDebug operator<<(QDebug dbg, const NSObject *nsObject)
+{
+    return dbg << (nsObject ? nsObject.description.UTF8String : "NSObject(0x0)");
+}
+
+QDebug operator<<(QDebug dbg, CFStringRef stringRef)
+{
+    if (!stringRef)
+        return dbg << "CFStringRef(0x0)";
+
+    if (const UniChar *chars = CFStringGetCharactersPtr(stringRef))
+        dbg << QString::fromRawData(reinterpret_cast<const QChar *>(chars), CFStringGetLength(stringRef));
+    else
+        dbg << QString::fromCFString(stringRef);
+
+    return dbg;
+}
+
+// Prevents breaking the ODR in case we introduce support for more types
+// later on, and lets the user override our default QDebug operators.
+#define QT_DECLARE_WEAK_QDEBUG_OPERATOR_FOR_CF_TYPE(CFType) \
+    __attribute__((weak)) Q_DECLARE_QDEBUG_OPERATOR_FOR_CF_TYPE(CFType)
+
+QT_FOR_EACH_CORE_FOUNDATION_TYPE(QT_DECLARE_WEAK_QDEBUG_OPERATOR_FOR_CF_TYPE);
+QT_FOR_EACH_MUTABLE_CORE_FOUNDATION_TYPE(QT_DECLARE_WEAK_QDEBUG_OPERATOR_FOR_CF_TYPE);
+QT_FOR_EACH_CORE_GRAPHICS_TYPE(QT_DECLARE_WEAK_QDEBUG_OPERATOR_FOR_CF_TYPE);
+QT_FOR_EACH_MUTABLE_CORE_GRAPHICS_TYPE(QT_DECLARE_WEAK_QDEBUG_OPERATOR_FOR_CF_TYPE);
+
+// -------------------------------------------------------------------------
+
 QAppleOperatingSystemVersion qt_apple_os_version()
 {
     QAppleOperatingSystemVersion v = {0, 0, 0};