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ExtensionClass.h

/*****************************************************************************

  Copyright (c) 1996-2002 Zope Corporation and Contributors.
  All Rights Reserved.

  This software is subject to the provisions of the Zope Public License,
  Version 2.0 (ZPL).  A copy of the ZPL should accompany this distribution.
  THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
  WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
  FOR A PARTICULAR PURPOSE

 ****************************************************************************/

/*

  $Id: ExtensionClass.h,v 1.2 2003/06/02 18:51:04 wdelano Exp $

  Extension Class Definitions

  Implementing base extension classes
  
    A base extension class is implemented in much the same way that an
    extension type is implemented, except:
  
    - The include file, 'ExtensionClass.h', must be included.
 
    - The type structure is declared to be of type
        'PyExtensionClass', rather than of type 'PyTypeObject'.
 
    - The type structure has an additional member that must be defined
        after the documentation string.  This extra member is a method chain
        ('PyMethodChain') containing a linked list of method definition
        ('PyMethodDef') lists.  Method chains can be used to implement
        method inheritance in C.  Most extensions don't use method chains,
        but simply define method lists, which are null-terminated arrays
        of method definitions.  A macro, 'METHOD_CHAIN' is defined in
        'ExtensionClass.h' that converts a method list to a method chain.
        (See the example below.)
  
    - Module functions that create new instances must be replaced by an
        '__init__' method that initializes, but does not create storage for 
        instances.
  
    - The extension class must be initialized and exported to the module
        with::
  
            PyExtensionClass_Export(d,"name",type);
  
        where 'name' is the module name and 'type' is the extension class
        type object.
  
    Attribute lookup
  
        Attribute lookup is performed by calling the base extension class
        'getattr' operation for the base extension class that includes C
        data, or for the first base extension class, if none of the base
        extension classes include C data.  'ExtensionClass.h' defines a
        macro 'Py_FindAttrString' that can be used to find an object's
        attributes that are stored in the object's instance dictionary or
        in the object's class or base classes::
  
           v = Py_FindAttrString(self,name);
  
        In addition, a macro is provided that replaces 'Py_FindMethod'
        calls with logic to perform the same sort of lookup that is
        provided by 'Py_FindAttrString'.
  
    Linking
  
        The extension class mechanism was designed to be useful with
        dynamically linked extension modules.  Modules that implement
        extension classes do not have to be linked against an extension
        class library.  The macro 'PyExtensionClass_Export' imports the
        'ExtensionClass' module and uses objects imported from this module
        to initialize an extension class with necessary behavior.
 
  If you have questions regarding this software,
  contact:
 
  
  If you have questions regarding this software,
  contact:
    Zope Corporation
    info@zope.com
 
    (540) 371-6909

*/

#ifndef EXTENSIONCLASS_H
#define EXTENSIONCLASS_H

#include "Python.h"
#include "import.h"

/* Declarations for objects of type ExtensionClass */

typedef struct {
      PyObject_VAR_HEAD
      char *tp_name; /* For printing */
      int tp_basicsize, tp_itemsize; /* For allocation */
      
      /* Methods to implement standard operations */
      
      destructor tp_dealloc;
      printfunc tp_print;
      getattrfunc tp_getattr;
      setattrfunc tp_setattr;
      cmpfunc tp_compare;
      reprfunc tp_repr;
      
      /* Method suites for standard classes */
      
      PyNumberMethods *tp_as_number;
      PySequenceMethods *tp_as_sequence;
      PyMappingMethods *tp_as_mapping;

      /* More standard operations (at end for binary compatibility) */

      hashfunc tp_hash;
      ternaryfunc tp_call;
      reprfunc tp_str;
      getattrofunc tp_getattro;
      setattrofunc tp_setattro;
      /* Space for future expansion */
      long tp_xxx3;
      long tp_xxx4;

      char *tp_doc; /* Documentation string */

#ifdef COUNT_ALLOCS
      /* these must be last */
      int tp_alloc;
      int tp_free;
      int tp_maxalloc;
      struct _typeobject *tp_next;
#endif

  /* Here's the juicy stuff: */

  /* Put your method chain here.  If you just have a method
     list, you can use the METHON_CHAIN macro to make a chain.
     */
  PyMethodChain methods;

  /* You may set certain flags here. */
  long class_flags;

  /* The following flags are used by ExtensionClass */
#define EXTENSIONCLASS_DYNAMIC_FLAG       1 << 0
#define EXTENSIONCLASS_BINDABLE_FLAG      1 << 2
#define EXTENSIONCLASS_METHODHOOK_FLAG    1 << 3
#define EXTENSIONCLASS_INSTDICT_FLAG      1 << 4
#define EXTENSIONCLASS_NOINSTDICT_FLAG    1 << 5
#define EXTENSIONCLASS_BASICNEW_FLAG      1 << 6
#define EXTENSIONCLASS_PYTHONICATTR_FLAG  1 << 7
#define EXTENSIONCLASS_USERGETATTR_FLAG   1 << 8
#define EXTENSIONCLASS_USERSETATTR_FLAG   1 << 9
#define EXTENSIONCLASS_USERDELATTR_FLAG   1 << 10

  /* The following flags are for use by extension class developers. */
#define EXTENSIONCLASS_USER_FLAG1     1 << 16
#define EXTENSIONCLASS_USER_FLAG2     1 << 17
#define EXTENSIONCLASS_USER_FLAG3     1 << 18
#define EXTENSIONCLASS_USER_FLAG4     1 << 19
#define EXTENSIONCLASS_USER_FLAG5     1 << 20
#define EXTENSIONCLASS_USER_FLAG6     1 << 21
#define EXTENSIONCLASS_USER_FLAG7     1 << 22
#define EXTENSIONCLASS_USER_FLAG8     1 << 23
#define EXTENSIONCLASS_USER_FLAG9     1 << 24
#define EXTENSIONCLASS_USER_FLAG10    1 << 25
#define EXTENSIONCLASS_USER_FLAG11    1 << 26
#define EXTENSIONCLASS_USER_FLAG12    1 << 27
#define EXTENSIONCLASS_USER_FLAG13    1 << 28
#define EXTENSIONCLASS_USER_FLAG14    1 << 29
#define EXTENSIONCLASS_USER_FLAG15    1 << 30
#define EXTENSIONCLASS_USER_FLAG16    1 << 31

  /* This is the class dictionary, which is normally created for you.
     If you wish, you can provide your own class dictionary object.
     If you do provide your own class dictionary, it *must* be
     a mapping object.  If the object given is also an extension
     instance, then sub-class instance dictionaries will be created
     by calling the class dictionary's class with zero argumemts.
     Otherwise, subclass dictionaries will be of the default type.
     */
  PyObject *class_dictionary;

  /* You should not set the remaining members. */
  PyObject *bases;
  PyObject *reserved;
} PyExtensionClass;

/* Following are macros that are needed or useful for defining extension
   classes:
   */

/* This macro redefines Py_FindMethod to do attribute for an attribute
   name given by a C string lookup using extension class meta-data.
   This is used by older getattr implementations.

   This macro is used in base class implementations of tp_getattr to
   lookup methods or attributes that are not managed by the base type
   directly.  The macro is generally used to search for attributes
   after other attribute searches have failed.
   
   Note that in Python 1.4, a getattr operation may be provided that
   uses an object argument. Classes that support this new operation
   should use Py_FindAttr.
   */
#define Py_FindMethod(M,SELF,NAME) \
  (PyExtensionClassCAPI->getattrs((SELF),(NAME)))

/* Do method or attribute lookup for an attribute name given by a C
   string using extension class meta-data.

   This macro is used in base class implementations of tp_getattro to
   lookup methods or attributes that are not managed by the base type
   directly.  The macro is generally used to search for attributes
   after other attribute searches have failed.
   
   Note that in Python 1.4, a getattr operation may be provided that
   uses an object argument. Classes that support this new operation
   should use Py_FindAttr.
   */
#define Py_FindAttrString(SELF,NAME) \
  (PyExtensionClassCAPI->getattrs((SELF),(NAME)))

/* Do method or attribute lookup using extension class meta-data.

   This macro is used in base class implementations of tp_getattr to
   lookup methods or attributes that are not managed by the base type
   directly.  The macro is generally used to search for attributes
   after other attribute searches have failed.  */
#define Py_FindAttr(SELF,NAME) (PyExtensionClassCAPI->getattro((SELF),(NAME)))

/* Do method or attribute assignment for an attribute name given by a
   C string using extension class meta-data.

   This macro is used in base class implementations of tp_setattr to
   set attributes that are not managed by the base type directly.  The
   macro is generally used to assign attributes after other attribute
   attempts to assign attributes have failed.

   Note that in Python 1.4, a setattr operation may be provided that
   uses an object argument. Classes that support this new operation
   should use PyEC_SetAttr.
   */
#define PyEC_SetAttrString(SELF,NAME,V) \
  (PyExtensionClassCAPI->setattrs((SELF),(NAME),(V)))

/* Do attribute assignment for an attribute.

   This macro is used in base class implementations of tp_setattro to
   set attributes that are not managed by the base type directly.  The
   macro is generally used to assign attributes after other attribute
   attempts to assign attributes have failed.
   */
#define PyEC_SetAttr(SELF,NAME,V) \
     (PyExtensionClassCAPI->setattro((SELF),(NAME),(V)))

/* Import the ExtensionClass CAPI */
#define ExtensionClassImported \
  (PyExtensionClassCAPI=PyCObject_Import("ExtensionClass","CAPI"))

/* Make sure the C interface has been imported and import it if necessary.
   This can be used in an if.
   */
#define MakeSureExtensionClassImported \
  (PyExtensionClassCAPI || \
   (PyExtensionClassCAPI=PyCObject_Import("ExtensionClass","CAPI")))


/* Export an Extension Base class in a given module dictionary with a
   given name and ExtensionClass structure.
   */
#define PyExtensionClass_Export(D,N,T) \
 if(PyExtensionClassCAPI || \
   (PyExtensionClassCAPI= (struct ExtensionClassCAPIstruct*) \
                          PyCObject_Import("ExtensionClass","CAPI"))) \
   { PyExtensionClassCAPI->Export(D,N,&T); }

/* Convert a method list to a method chain.  */
#define METHOD_CHAIN(DEF) { DEF, NULL }

/* The following macro checks whether a type is an extension class: */
#define PyExtensionClass_Check(TYPE) \
  ((PyObject*)(TYPE)->ob_type==PyExtensionClassCAPI->ExtensionClassType)

/* The following macro checks whether an instance is an extension instance: */
#define PyExtensionInstance_Check(INST) \
  ((PyObject*)(INST)->ob_type->ob_type== \
     PyExtensionClassCAPI->ExtensionClassType)

/* The following macro checks for errors and prints out an error
   message that is more informative than the one given by Python when
   an extension module initialization fails.
   */
#define CHECK_FOR_ERRORS(MESS) \
if(PyErr_Occurred()) { \
  PyObject *__sys_exc_type, *__sys_exc_value, *__sys_exc_traceback; \
  PyErr_Fetch( &__sys_exc_type, &__sys_exc_value, \
             &__sys_exc_traceback); \
  fprintf(stderr, # MESS ":\n\t"); \
  PyObject_Print(__sys_exc_type, stderr,0); \
  fprintf(stderr,", "); \
  PyObject_Print(__sys_exc_value, stderr,0); \
  fprintf(stderr,"\n"); \
  fflush(stderr); \
  Py_FatalError(# MESS); \
}

/* The following macro can be used to define an extension base class
   that only provides method and that is used as a pure mix-in class. */
#define PURE_MIXIN_CLASS(NAME,DOC,METHODS) \
static PyExtensionClass NAME ## Type = { PyObject_HEAD_INIT(NULL) \
      0, # NAME, sizeof(PyPureMixinObject), 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, \
      0, 0, 0, 0, 0, 0, 0, DOC, {METHODS, NULL}, \
        EXTENSIONCLASS_BASICNEW_FLAG}

/* The following macros provide limited access to extension-class
   method facilities. */

/* Test for an ExtensionClass method: */
#define PyECMethod_Check(O) \
  ((PyObject*)(O)->ob_type==PyExtensionClassCAPI->MethodType)

/* Create a method object that wraps a callable object and an
   instance. Note that if the callable object is an extension class
   method, then the new method will wrap the callable object that is
   wrapped by the extension class method.  Also note that if the
   callable object is an extension class method with a reference
   count of 1, then the callable object will be rebound to the
   instance and returned with an incremented reference count.
   */
#define PyECMethod_New(CALLABLE,INST) \
  (PyExtensionClassCAPI->Method_New(CALLABLE,INST))

/* Return the instance that is bound by an extension class method. */
#define PyECMethod_Self(M) (((PyECMethodObject*)M)->self)

/* Check whether an object has an __of__ method for returning itself
   in the context of it's container. */
#define has__of__(O) \
   ((O)->ob_type->ob_type == \
        (PyTypeObject*)PyExtensionClassCAPI->ExtensionClassType && \
    (((PyExtensionClass*)((O)->ob_type))->class_flags & \
     EXTENSIONCLASS_BINDABLE_FLAG))

/* The following macros are used to check whether an instance
   or a class' instanses have instance dictionaries: */
#define HasInstDict(O) \
   ((((PyExtensionClass*)((O)->ob_type))->class_flags & \
     EXTENSIONCLASS_INSTDICT_FLAG))
#define ClassHasInstDict(O) (O->class_flags & EXTENSIONCLASS_INSTDICT_FLAG)

/* Get an object's instance dictionary.  Use with caution */
#define INSTANCE_DICT(inst) \
*(((PyObject**)inst) + (inst->ob_type->tp_basicsize/sizeof(PyObject*) - 1))

/* Test whether an ExtensionClass, S, is a subclass of ExtensionClass C. */
#define ExtensionClassSubclass_Check(S,C) ( \
  ((PyObject*)(S)->ob_type==PyExtensionClassCAPI->ExtensionClassType) && \
  ((PyObject*)(C)->ob_type==PyExtensionClassCAPI->ExtensionClassType) && \
  (PyExtensionClassCAPI->issubclass((PyExtensionClass *)(S), \
                            (PyExtensionClass *)(C))))

/* Test whether an ExtensionClass instance , I, is a subclass of 
   ExtensionClass C. */
#define ExtensionClassSubclassInstance_Check(I,C) ( \
  ((PyObject*)(I)->ob_type->ob_type== \
                             PyExtensionClassCAPI->ExtensionClassType) && \
  ((PyObject*)(C)->ob_type==PyExtensionClassCAPI->ExtensionClassType) && \
  (PyExtensionClassCAPI->issubclass((PyExtensionClass *)((I)->ob_type), \
                            (PyExtensionClass *)(C))))

/* This let's you define built-in class methods. */
#define METH_CLASS_METHOD (2 << 17)

/*****************************************************************************

  WARNING: EVERYTHING BELOW HERE IS PRIVATE TO THE EXTENSION CLASS INTERFACE
           IMPLEMENTATION AND IS SUBJECT TO CHANGE !!!

 *****************************************************************************/

static struct ExtensionClassCAPIstruct {
  int (*Export)(PyObject *dict, char *name, PyExtensionClass *ob_type);
  PyObject *(*getattrs)(PyObject *, char *);
  PyObject *(*getattro)(PyObject *, PyObject *);
  int (*setattrs)(PyObject *, char *, PyObject *);
  int (*setattro)(PyObject *, PyObject *, PyObject *);
  PyObject *ExtensionClassType;
  PyObject *MethodType;
  PyObject *(*Method_New)(PyObject *callable, PyObject *inst);
  int (*issubclass)(PyExtensionClass *sub, PyExtensionClass *type);
} *PyExtensionClassCAPI = NULL;

typedef struct { PyObject_HEAD } PyPureMixinObject;

typedef struct {
  PyObject_HEAD
  PyTypeObject *type;
  PyObject     *self;
  PyObject     *meth;
} PyECMethodObject; /* AKA PMethod */

/* The following is to avoid whining from 1.5 :-) */
#define PyCObject_Import PyCObject_Import14

static void *
PyCObject_Import14(char *module_name, char *name)
{
  PyObject *m, *c;
  void *r=NULL;
  
  if((m=PyImport_ImportModule(module_name)))
    {
      if((c=PyObject_GetAttrString(m,name)))
      {
        r=PyCObject_AsVoidPtr(c);
        Py_DECREF(c);
      }
      Py_DECREF(m);
    }

  return r;
}

#endif



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