NOTE:

While the primary intention of this pretty printing implementation is
to provide what Qt Creator needs, it can sometimes be used in plain
GDB and LLDB sessions, too.

This features is provided as-is. There is no guarantee this works in any
way outside Qt Creator, this setup is not officially supported.
Bugreports or (better!) patches are welcome.



With

        python import sys
        python sys.path.insert(1, '<path/to/qtcreator>/share/qtcreator/debugger/')
        python from gdbbridge import *

in .gdbinit there is a new "GDB command", called "pp".

With code like

        int main(int argc, char *argv[])
        {
            QString ss = "Hello";
            QApplication app(argc, argv);
            app.setObjectName(ss);
            // break here
        }

    the "pp" command can be used as follows:

    (gdb) pp app
    app =
       [
          <QGuiApplication> = {"Hello"}
          staticMetaObject = <QMetaObject> = {""}
          [parent] = <QObject *> = {"0x0"}
          [children] = <QObjectList> = {"<3 items>"}
          [properties] = "<>0 items>"
          [methods] = "<6 items>"
          [signals] = "<1 items>"
       ],<QApplication> = {"Hello"}

    (gdb) pp app [properties],[children]
    app =
       [
          <QGuiApplication> = {"Hello"}
          staticMetaObject = <QMetaObject> = {""}
          [parent] = <QObject *> = {"0x0"}
          [children] = [
             <QObject> = {""}
             <QObject> = {""}
             <QObject> = {"fusion"}
          ],<QObjectList> = {"<3 items>"}
          [properties] = [
             windowIcon = <QVariant (QIcon)> = {""}
             cursorFlashTime = <QVariant (int)> = {"1000"}
             doubleClickInterval = <QVariant (int)> = {"400"}
             keyboardInputInterval = <QVariant (int)> = {"400"}
             wheelScrollLines = <QVariant (int)> = {"3"}
             globalStrut = <QVariant (QSize)> = {"(0, 0)"}
             startDragTime = <QVariant (int)> = {"500"}
             startDragDistance = <QVariant (int)> = {"10"}
             styleSheet = <QVariant (QString)> = {""}
             autoSipEnabled = <QVariant (bool)> = {"true"}
          ],"<10 items>"
          [methods] = "<6 items>"
          [signals] = "<1 items>"
       ],<QApplication> = {"Hello"}

    (gdb) pp ss
    ss =
       <QString> = {"Hello"}

Or for LLDB (.lldbinit or directly in the LLDB interpreter):

      command script import <path/to/qtcreator>/share/qtcreator/debugger/lldbbridge.py

This will add LLDB summary providers for all the Qt types in a new type category named 'Qt'.



In order to hook a new debugger backend into this "common pretty printing system",
the backend should expose a Python API containing at least the following:


class Value:
    name() -> string                      # Name of this thing or None
    type() -> Type                        # Type of this value
    asBytes() -> bytes                    # Memory contents of this object, or None
    address() -> int                      # Address of this object, or None
    dereference() -> Value                # Dereference if value is pointer,
                                          # remove reference if value is reference.
    hasChildren() -> bool                 # Whether this object has subobjects.
    expand() -> bool                      # Make sure that children are accessible.
    nativeDebuggerValue() -> string       # Dumper value returned from the debugger

    childFromName(string name) -> Value   # (optional)
    childFromField(Field field) -> Value  # (optional)
    childFromIndex(int position) -> Value # (optional)


class Type:
    name() -> string                      # Full name of this type
    bitsize() -> int                      # Size of type in bits
    code() -> TypeCodeTypedef
            | TypeCodeStruct
            | TypeCodeVoid
            | TypeCodeIntegral
            | TypeCodeFloat
            | TypeCodeEnum
            | TypeCodePointer
            | TypeCodeArray
            | TypeCodeComplex
            | TypeCodeReference
            | TypeCodeFunction
            | TypeCodeMemberPointer
            | TypeCodeUnresolvable

    unqualified() -> Type                 # Type without const/volatile
    target() -> Type                      # Type dereferenced if it is a pointer type, element if array etc
    stripTypedef() -> Type                # Type with typedefs removed
    fields() -> [ Fields ]                # List of fields (member and base classes) of this type

    templateArgument(int pos, bool numeric) -> Type or int   # (optional)

class Field:
    name() -> string                      # Name of member, None for anonymous items
    isBaseClass() -> bool                 # Whether this is a base class or normal member
    type() -> Type                        # Type of this member
    parentType() -> Type                  # Type of class this member belongs to
    bitsize() -> int                      # Size of member in bits
    bitpos() -> int                       # Offset of member in parent type in bits



parseAndEvaluate(string: expr) -> Value   # or None if not possible.
lookupType(string: name) -> Type          # or None if not possible.
listOfLocals() -> [ Value ]               # List of items currently in scope.
readRawMemory(ULONG64 address, ULONG size) -> bytes # Read a block of data from the virtual address space