class_definition.h

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/** @file
 *  @author Bram de Greve (bram@cocamware.com)
 *  @author Tom De Muer (tom@cocamware.com)
 *
 *  *** BEGIN LICENSE INFORMATION ***
 *  
 *  The contents of this file are subject to the Common Public Attribution License 
 *  Version 1.0 (the "License"); you may not use this file except in compliance with 
 *  the License. You may obtain a copy of the License at 
 *  http://lass.sourceforge.net/cpal-license. The License is based on the 
 *  Mozilla Public License Version 1.1 but Sections 14 and 15 have been added to cover 
 *  use of software over a computer network and provide for limited attribution for 
 *  the Original Developer. In addition, Exhibit A has been modified to be consistent 
 *  with Exhibit B.
 *  
 *  Software distributed under the License is distributed on an "AS IS" basis, WITHOUT 
 *  WARRANTY OF ANY KIND, either express or implied. See the License for the specific 
 *  language governing rights and limitations under the License.
 *  
 *  The Original Code is LASS - Library of Assembled Shared Sources.
 *  
 *  The Initial Developer of the Original Code is Bram de Greve and Tom De Muer.
 *  The Original Developer is the Initial Developer.
 *  
 *  All portions of the code written by the Initial Developer are:
 *  Copyright (C) 2004-2025 the Initial Developer.
 *  All Rights Reserved.
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 *  Contributor(s):
 *
 *  Alternatively, the contents of this file may be used under the terms of the 
 *  GNU General Public License Version 2 or later (the GPL), in which case the 
 *  provisions of GPL are applicable instead of those above.  If you wish to allow use
 *  of your version of this file only under the terms of the GPL and not to allow 
 *  others to use your version of this file under the CPAL, indicate your decision by 
 *  deleting the provisions above and replace them with the notice and other 
 *  provisions required by the GPL License. If you do not delete the provisions above,
 *  a recipient may use your version of this file under either the CPAL or the GPL.
 *  
 *  *** END LICENSE INFORMATION ***
 */
 
#ifndef LASS_GUARDIAN_OF_INCLUSION_PYTHON_CLASS_DEFINITION_H
#define LASS_GUARDIAN_OF_INCLUSION_PYTHON_CLASS_DEFINITION_H
 
#include "python_common.h"
#include "pyobject_special_methods.h"
#include "overload_link.h"
#include "export_traits.h"
#include "../util/shared_ptr.h"
 
namespace lass
{
    namespace python
    {
        /** @defgroup ClassDefinition Class Definitions
         *  @brief Defining Python classes from C++ with methods, properties, operators, and nested types.
         *
         *  This module provides the internal machinery used by the class export macros to define
         *  Python classes backed by C++ types. A class definition aggregates constructors, methods
         *  (including Python special methods/operators), properties, static members, nested classes
         *  and enums, and then materializes a Python type when frozen.
         *
         *
         *  ### Class Components
         *
         *  A Python class can contain:
         *
         *  - **Constructors**: Multiple overloads via \_\_new__ dispatchers
         *  - **Methods**: Regular instance methods with overload support
         *  - **Free Methods**: Functions that operate on the instance but are not members
         *  - **Static Methods**: Class-level methods accessible without instances
         *  - **Operators**: Python special methods (\_\_add__, \_\_eq__, etc.)
         *  - **Properties**: Getter/setter pairs for attribute access
         *  - **Public Members**: Direct access to public member variables
         *  - **Static Constants**: Class-level constant values
         *  - **Nested Classes**: Inner classes defined within the outer class
         *  - **Nested Enums**: Enum types scoped to the class
         *
         *
         *  ### Usage Overview
         *
         *  To export a C++ class to Python, you typically use macros that work with ClassDefinition:
         *
         *  ```cpp
         *  // Define class in header
         *  class MyClass: public PyObjectPlus
         *  {
         *      PY_HEADER(PyObjectPlus)
         *  public:
         *      MyClass();
         *      MyClass(int value);
         *      MyClass(const std::string& name, double factor);
         *      
         *      void process();
         *      void process(int iterations);                    // Overload #1 (member)
         *      int calculate(int input) const;
         *      std::string getName() const;
         *      void setName(const std::string& name);
         *      static int getGlobalCount();
         *      std::string toString() const;                    // For __str__
         *      
         *      int publicValue;
         *      static const int MAX_SIZE = 100;
         *  };
         *
         *  // Free functions for export as methods
         *  void reset(MyClass* obj);
         *  void process(MyClass* obj, const std::string& mode); // Overload #2 (free function)
         *  double computeScore(const MyClass& obj, double multiplier);
         *  MyClass combine(const MyClass& a, const MyClass& b);
         *  
         *  // Special method implementations
         *  bool operator==(const MyClass& a, const MyClass& b);
         *  bool operator<(const MyClass& a, const MyClass& b);
         *  MyClass operator+(const MyClass& a, const MyClass& b);
         *  MyClass operator-(const MyClass& a, const MyClass& b);
         *  std::string repr(const MyClass& obj);                // For __repr__
         *  size_t hash(const MyClass& obj);                     // For __hash__
         *
         *  // Register class methods and properties in source
         *  PY_DECLARE_CLASS_NAME_DOC(MyClass, "MyClass", "Demonstration class with various binding types")
         *  
         *  // Multiple constructor overloads
         *  PY_CLASS_CONSTRUCTOR_0(MyClass)
         *  PY_CLASS_CONSTRUCTOR_1(MyClass, int)
         *  PY_CLASS_CONSTRUCTOR_2(MyClass, const std::string&, double)
         *  
         *  // Mixed overloading: regular methods + free functions for same Python method
         *  PY_CLASS_METHOD(MyClass, process)                           // void process()
         *  PY_CLASS_METHOD_1(MyClass, process, int)                    // void process(int)
         *  PY_CLASS_FREE_METHOD_NAME(MyClass, process, "process")      // void process(MyClass*, const std::string&)
         *  
         *  // Other regular methods
         *  PY_CLASS_METHOD_DOC(MyClass, calculate, "Calculate result from input value")
         *  PY_CLASS_STATIC_METHOD(MyClass, getGlobalCount)
         *  
         *  // Properties (getter/setter pairs)
         *  PY_CLASS_MEMBER_RW_DOC(MyClass, name, getName, setName, "Object name property")
         *  
         *  // Public member access
         *  PY_CLASS_MEMBER_R(MyClass, publicValue)
         *  
         *  // Free functions as methods (various forms)
         *  PY_CLASS_FREE_METHOD(MyClass, reset)
         *  PY_CLASS_FREE_METHOD_NAME_DOC(MyClass, computeScore, "compute_score", "Calculate score with multiplier")
         *  PY_CLASS_FREE_METHOD_DOC(MyClass, combine, "Combine two objects")
         *  
         *  // Python special methods via member and free functions
         *  PY_CLASS_METHOD_NAME(MyClass, toString, methods::_str_)          // Member function for __str__
         *  PY_CLASS_FREE_METHOD_NAME(MyClass, repr, methods::_repr_)       // Free function for __repr__
         *  PY_CLASS_FREE_METHOD_NAME(MyClass, hash, methods::_hash_)       // Free function for __hash__
         *  
         *  // Comparison and arithmetic operators
         *  PY_CLASS_FREE_METHOD_NAME(MyClass, operator==, methods::_eq_)
         *  PY_CLASS_FREE_METHOD_NAME(MyClass, operator<, methods::_lt_)
         *  PY_CLASS_FREE_METHOD_NAME(MyClass, operator+, methods::_add_)
         *  PY_CLASS_FREE_METHOD_NAME(MyClass, operator-, methods::_sub_)
         *  
         *  // Static constants and values
         *  PY_CLASS_STATIC_CONST(MyClass, "MAX_SIZE", MyClass::MAX_SIZE)
         *  PY_CLASS_STATIC_CONST(MyClass, "VERSION", "1.2.3")
         *
         *  // Add to module
         *  PY_MODULE_CLASS(mymodule, MyClass)
         *  ```
         *  
         *  @ingroup Python
         */
        class EnumDefinitionBase;
 
        namespace impl
        {
            LASS_PYTHON_DLL PyMethodDef LASS_CALL createPyMethodDef(
                const char *ml_name, PyCFunction ml_meth, int ml_flags, 
                const char *ml_doc);
            LASS_PYTHON_DLL PyGetSetDef LASS_CALL createPyGetSetDef(
                const char* name, getter get, setter set, const char* doc, void* closure);
 
            LASS_PYTHON_DLL void LASS_CALL dealloc(PyObject* obj);
            LASS_PYTHON_DLL PyObject* LASS_CALL repr(PyObject* obj);
            LASS_PYTHON_DLL PyObject* LASS_CALL str(PyObject* obj);
 
            class NamePredicate
            {
            public:
                NamePredicate(const char* name): name_(name) {}
                template <typename T> bool operator()(const T& x) const { return cmp(x.name()); }
                bool operator()(const PyMethodDef& x) const { return cmp(x.ml_name); }
                template <typename T> bool operator()(T* x) const { return (*this)(*x); }
            private:
                bool cmp(const char* name) const { return name && strcmp(name, name_) == 0; }
                const char* name_;
            };
 
            class StaticMemberHelper
            {
            public:
                virtual ~StaticMemberHelper() {}
                virtual TPyObjPtr build() const = 0;
            };
            typedef util::SharedPtr<StaticMemberHelper> TStaticMemberHelperPtr;
 
            template <typename T>
            class StaticMemberHelperObject: public StaticMemberHelper
            {
            public:
                StaticMemberHelperObject(const T& obj): obj_(obj) {}
                TPyObjPtr build() const override { return TPyObjPtr(PyExportTraits<const T>::build(obj_)); }
            private:
                const T obj_;
            };
            template <typename T, size_t N>
            class StaticMemberHelperObject<T[N]>: public StaticMemberHelper
            {
            public:
                StaticMemberHelperObject(const T obj[N]): obj_(obj) {}
                TPyObjPtr build() const override { return TPyObjPtr(PyExportTraits<const T*>::build(obj_)); }
            private:
                const T* obj_;
            };
            template <>
            class StaticMemberHelperObject<PyObject*>: public StaticMemberHelper
            {
            public:
                StaticMemberHelperObject(PyObject* obj): obj_(obj) {}
                TPyObjPtr build() const override { return obj_; }
            private:
                TPyObjPtr obj_;
            };
            template <typename T>
            inline TStaticMemberHelperPtr staticMemberHelperObject(const T& obj)
            {
                return TStaticMemberHelperPtr(new StaticMemberHelperObject<T>(obj));
            }
 
            class StaticMember
            {
            public:
                StaticMember(const char* name, const TStaticMemberHelperPtr member): member_(member), name_(name) {}
                const TStaticMemberHelperPtr& member() const { return member_; }
                const char* name() const { return name_; }
            private:
                TStaticMemberHelperPtr member_;
                const char* name_;
            };
 
            struct LASS_PYTHON_DLL CompareFunc
            {
                PyCFunction dispatcher;
                int op;
                CompareFunc(PyCFunction dispatcher, int op): dispatcher(dispatcher), op(op) {}
            };
 
            template <typename CppClass> PyObject* richCompareDispatcher(PyObject* self, PyObject* other, int op)
            {
                return CppClass::_lassPyClassDef.callRichCompare(self, other, op);
            }
 
            /** Definition of a Python class.
             *
             *  Collects all information required to define a Python type that wraps a C++ class.
             *  The definition accumulates constructors, methods (including Python slot methods),
             *  properties, static members, and nested types. When ready, call freezeDefinition()
             *  to create the underlying `PyTypeObject` and (optionally) inject it into a module
             *  or as a nested type.
             *
             *  The ClassDefinition class is typically not used directly by user code. Instead, use the
             *  provided macros in pyobject_macros.h that work with ClassDefinition instances.
             *
             *  @ingroup ClassDefinition
             */
            class LASS_PYTHON_DLL ClassDefinition
            {
            public:
                typedef void(*TClassRegisterHook)(); /// Function to call during registration of the class (optional).
                typedef int TSlotID; ///< Identifier type for indexing into the internal Python slot table.
 
                /** Construct a class definition.
                 *  @param name      Python class name
                 *  @param doc       Class docstring (must outlive the definition unless changed via setDoc())
                 *  @param typeSize  Size of the Python instance struct (derived from PyObject)
                 *  @param richcmp   Optional rich-compare function (may be nullptr)
                 *  @param parent    Optional parent to nest this class into (may be nullptr)
                 *  @param registerHook Optional hook called when the class is registered
                 */
                ClassDefinition(const char* name, const char* doc, Py_ssize_t typeSize,
                    richcmpfunc richcmp, ClassDefinition* parent, TClassRegisterHook registerHook);
                /** Destructor. */
                ~ClassDefinition();
 
                /** Get the Python type object  (available after freezeDefinition() has been called). */
                /// @{
                PyTypeObject* type();
                const PyTypeObject* type() const;
                /// @}
 
                /** Get the class name. */
                const char* name() const;
                /** Get the class docstring. */
                const char* doc() const;
                /** Set the class docstring.
                 *  Note: the provided string must remain valid until another docstring is set.
                 */
                void setDoc(const char* doc);
                /** Set the class docstring if non-null (keeps existing one if nullptr). */
                void setDocIfNotNull(const char* doc);
 
                /** Add a constructor overload (\_\_init__ dispatcher).
                 *  @param dispatcher   New-function dispatcher
                 *  @param overloadChain Reference to overload chain
                 */
                void addConstructor(newfunc dispatcher, newfunc& overloadChain);
 
                /** Add a named method.
                 *  @param name, slot Python method name or special slot
                 *  @param doc  Method docstring
                 *  @param dispatcher Dispatcher implementing the method
                 *  @param overloadChain Overload chain for this name
                 */
                /// @{
                void addMethod(const char* name, const char* doc, PyCFunction dispatcher, OverloadLink& overloadChain);
                /** Add a comparator-slot method (rich compare operator). */
                void addMethod(const ComparatorSlot& slot, const char* doc, PyCFunction dispatcher, OverloadLink& overloadChain);
                /** Add a unary-slot method (e.g., \_\_neg__, \_\_pos__, ...). */ 
                void addMethod(const UnarySlot& slot, const char* doc, unaryfunc dispatcher, OverloadLink& overloadChain); 
                /** Add a binary-slot method (e.g., arithmetic, comparisons). */ 
                void addMethod(const BinarySlot& slot, const char* doc, binaryfunc dispatcher, OverloadLink& overloadChain); 
                /** Add a ternary-slot method. */
                void addMethod(const TernarySlot& slot, const char* doc, ternaryfunc dispatcher, OverloadLink& overloadChain);
                /** Add a length-slot method (\_\_len__). */
                void addMethod(const LenSlot& slot, const char* doc, lenfunc dispatcher, OverloadLink& overloadChain);
                /** Add an ssize-arg-slot method. */
                void addMethod(const SsizeArgSlot& slot, const char* doc, ssizeargfunc dispatcher, OverloadLink& overloadChain);
                /** Add an ssize-obj-arg-slot method. */
                void addMethod(const SsizeObjArgSlot& slot, const char* doc, ssizeobjargproc dispatcher, OverloadLink& overloadChain);
                /** Add an obj-obj-slot method. */
                void addMethod(const ObjObjSlot& slot, const char* doc, objobjproc dispatcher, OverloadLink& overloadChain);
                /** Add an obj-obj-arg-slot method. */
                void addMethod(const ObjObjArgSlot& slot, const char* doc, objobjargproc dispatcher, OverloadLink& overloadChain);
                /** Add an iterator-slot method (\_\_iter__). */
                void addMethod(const IterSlot& slot, const char* doc, getiterfunc dispatcher, OverloadLink& overloadChain);
                /** Add an iternext-slot method (\_\_next__). */
                void addMethod(const IterNextSlot& slot, const char* doc, iternextfunc dispatcher, OverloadLink& overloadChain);
                /** Add an arg+kw-slot method (callable semantics). */
                void addMethod(const ArgKwSlot& slot, const char* doc, ternaryfunc dispatcher, OverloadLink& overloadChain);
                /** Add an inquiry-slot method. */
                void addMethod(const InquirySlot& slot, const char* doc, inquiry dispatcher, OverloadLink& overloadChain);
                /** Add a property with optional getter/setter. */
                void addGetSetter(const char* name, const char* doc, getter get, setter set);
                /** Add a static method with overload support. */
                void addStaticMethod(const char* name, const char* doc, PyCFunction dispatcher, PyCFunction& overloadChain);
                /// @}
            
                template <typename T> void addStaticConst(const char* name, const T& value)
                {
                    LASS_ASSERT(std::count_if(statics_.begin(), statics_.end(), NamePredicate(name)) == 0);
                    statics_.push_back(StaticMember(name, staticMemberHelperObject(value)));
                }
 
                /// @{
                /** Add a nested class definition (inner class). */
                void addInnerClass(ClassDefinition& innerClass);
                /** Add a nested enum definition (inner enum). */
                void addInnerEnum(EnumDefinitionBase* enumDefinition);
                /// @}
 
                /// @{
                /** Get raw pointer from a given slot id. */
                void* getSlot(TSlotID slotId);
                /** Set raw pointer for a given slot id. */
                void* setSlot(TSlotID slotId, void* value);
                template <typename Ptr> Ptr setSlot(TSlotID slotId, Ptr value)
                {
                    return reinterpret_cast<Ptr>(setSlot(slotId, reinterpret_cast<void*>(value)));
                }
                /// @}
 
                /** Finalize the definition and create the Python type.
                 *  If a module is provided, the type is added to that module.
                 */
                PyObject* freezeDefinition(PyObject* module = nullptr);
 
                /** Dispatch rich-compare for this class (used by operator slots). */
                PyObject* callRichCompare(PyObject* self, PyObject* other, int op);
 
            private:
 
                friend LASS_PYTHON_DLL PyObject* LASS_CALL establishMagicalBackLinks(PyObject* result, PyObject* self);
 
                template <typename T> friend struct ShadowTraits; // to have acces to implicitConvertersSlot_, see below.
 
                typedef std::vector<PyMethodDef> TMethods;
                typedef std::vector<PyGetSetDef> TGetSetters;
                typedef std::vector<CompareFunc> TCompareFuncs;
                typedef std::vector<StaticMember> TStaticMembers;
                typedef std::vector<ClassDefinition*> TClassDefs;
                typedef std::vector<EnumDefinitionBase*> TEnumDefs;
                typedef std::vector<PyType_Slot> TSlots;
 
                PyObject* freezeDefinition(PyObject* module, const char* scopeName);
 
                PyType_Spec spec_;
                TPyObjPtr type_;
                TSlots slots_;
                TMethods methods_;
                TGetSetters getSetters_;
                TCompareFuncs compareFuncs_;
                TStaticMembers statics_;
                TClassDefs innerClasses_;
                TClassDefs subClasses_;
                TEnumDefs innerEnums_;
                ClassDefinition* parent_;
                TClassRegisterHook classRegisterHook_;
                const char* className_;
                const char* doc_;
 
                /** Typeless slot for ExportTraits to store implicit converters.
                *  This used to be a static in the templated ExportTraits, but since
                *  the initial value is then defined in a header (PY_SHADOW_CASTERS
                *  is usually invoked in a header), this causes a static variable
                *  to be defined _per_ DLL, if that type is used in multiple DLLs.
                *  To avoid that, we moved it to header, which we know will be
                *  defined in a source file, and will thus exist only once.
                */
                void* implicitConvertersSlot_;
 
                bool isFrozen_;
            };
        }
    }
}
 
#endif