Debugger[New CDB]: Add support for "Select Widget to Watch".

in stopped state. Add helper for executing calls
to ExtensionContext including recording of output in
OutputCallback. Extend symbol resolution to return addresses
as well since QApplication::widgetAt() is ambiguous and needs
to be called by address. Add 'widgetat' extension command
to return the widget.

src/libs/qtcreatorcdbext/gdbmihelpers.cpp

@@ -35,6 +35,8 @@
 #include "stringutils.h"
 #include "iinterfacepointer.h"
 #include "base64.h"
+#include "symbolgroupvalue.h"
+#include "extensioncontext.h"
 
 #include <vector>
 
@@ -620,3 +622,51 @@ std::string gdbmiStack(CIDebugControl *debugControl,
     str << ']';
     return str.str();
 }
+
+// Find the widget of the application by calling QApplication::widgetAt().
+// Return "Qualified_ClassName:Address"
+
+static inline std::string msgWidgetParseError(std::wstring wo)
+{
+    replace(wo, L'\n', L';');
+    return "Output parse error :" + wStringToString(wo);
+}
+
+std::string widgetAt(const SymbolGroupValueContext &ctx, int x, int y, std::string *errorMessage)
+{
+    typedef SymbolGroupValue::SymbolList SymbolList;
+    // First, resolve symbol since there are ambiguities. Take the first one which is the
+    // overload for (int,int) and call by address instead off name to overcome that.
+    const std::string func = QtInfo::get(ctx).prependQtGuiModule("QApplication::widgetAt");
+    const SymbolList symbols = SymbolGroupValue::resolveSymbol(func.c_str(), ctx, errorMessage);
+    if (symbols.empty())
+        return std::string(); // Not a gui application, likely
+    std::ostringstream callStr;
+    callStr << std::showbase << std::hex << symbols.front().second
+            << std::noshowbase << std::dec << '(' << x << ',' << y << ')';
+    std::wstring wOutput;
+    if (!ExtensionContext::instance().call(callStr.str(), &wOutput, errorMessage))
+        return std::string();
+    // Returns: ".call returns\nclass QWidget * 0x00000000`022bf100\nbla...".
+    // Chop lines in front and after 'class ...' and convert first line.
+    const std::wstring::size_type classPos = wOutput.find(L"class ");
+    if (classPos == std::wstring::npos) {
+        *errorMessage = msgWidgetParseError(wOutput);
+        return std::string();
+    }
+    wOutput.erase(0, classPos + 6);
+    const std::wstring::size_type nlPos = wOutput.find(L'\n');
+    if (nlPos != std::wstring::npos)
+        wOutput.erase(nlPos, wOutput.size() - nlPos);
+    const std::string::size_type addressPos = wOutput.find(L" * 0x");
+    if (addressPos == std::string::npos) {
+        *errorMessage = msgWidgetParseError(wOutput);
+        return std::string();
+    }
+    // "QWidget * 0x00000000`022bf100" -> "QWidget:0x00000000022bf100"
+    wOutput.replace(addressPos, 3, L":");
+    const std::string::size_type sepPos = wOutput.find(L'`');
+    if (sepPos != std::string::npos)
+        wOutput.erase(sepPos, 1);
+    return wStringToString(wOutput);
+}