/*
 * tclOOInt.h --
 *
 *	This file contains the structure definitions and some of the function
 *	declarations for the object-system (NB: not Tcl_Obj, but ::oo).
 *
 * Copyright (c) 2006-2012 by Donal K. Fellows
 *
 * See the file "license.terms" for information on usage and redistribution of
 * this file, and for a DISCLAIMER OF ALL WARRANTIES.
 */

#ifndef TCL_OO_INTERNAL_H
#define TCL_OO_INTERNAL_H 1

#include "tclInt.h"
#include "tclOO.h"

/*
 * Hack to make things work with Objective C. Note that ObjC isn't really
 * supported, but we don't want to to be actively hostile to it. [Bug 2163447]
 */

#ifdef __OBJC__
#define Class	TclOOClass
#define Object	TclOOObject
#endif /* __OBJC__ */

/*
 * Forward declarations.
 */

struct CallChain;
struct Class;
struct Foundation;
struct Object;

/*
 * The data that needs to be stored per method. This record is used to collect
 * information about all sorts of methods, including forwards, constructors
 * and destructors.
 */

typedef struct Method {
    const Tcl_MethodType *typePtr;
				/* The type of method. If NULL, this is a
				 * special flag record which is just used for
				 * the setting of the flags field. */
    int refCount;
    ClientData clientData;	/* Type-specific data. */
    Tcl_Obj *namePtr;		/* Name of the method. */
    struct Object *declaringObjectPtr;
				/* The object that declares this method, or
				 * NULL if it was declared by a class. */
    struct Class *declaringClassPtr;
				/* The class that declares this method, or
				 * NULL if it was declared directly on an
				 * object. */
    int flags;			/* Assorted flags. Includes whether this
				 * method is public/exported or not. */
} Method;

/*
 * Pre- and post-call callbacks, to allow procedure-like methods to be fine
 * tuned in their behaviour.
 */

typedef int (TclOO_PreCallProc)(ClientData clientData, Tcl_Interp *interp,
	Tcl_ObjectContext context, Tcl_CallFrame *framePtr, int *isFinished);
typedef int (TclOO_PostCallProc)(ClientData clientData, Tcl_Interp *interp,
	Tcl_ObjectContext context, Tcl_Namespace *namespacePtr, int result);
typedef void (TclOO_PmCDDeleteProc)(ClientData clientData);
typedef ClientData (TclOO_PmCDCloneProc)(ClientData clientData);

/*
 * Procedure-like methods have the following extra information.
 */

typedef struct ProcedureMethod {
    int version;		/* Version of this structure. Currently must
				 * be 0. */
    Proc *procPtr;		/* Core of the implementation of the method;
				 * includes the argument definition and the
				 * body bytecodes. */
    int flags;			/* Flags to control features. */
    int refCount;
    ClientData clientData;
    TclOO_PmCDDeleteProc *deleteClientdataProc;
    TclOO_PmCDCloneProc *cloneClientdataProc;
    ProcErrorProc *errProc;	/* Replacement error handler. */
    TclOO_PreCallProc *preCallProc;
				/* Callback to allow for additional setup
				 * before the method executes. */
    TclOO_PostCallProc *postCallProc;
				/* Callback to allow for additional cleanup
				 * after the method executes. */
    GetFrameInfoValueProc *gfivProc;
				/* Callback to allow for fine tuning of how
				 * the method reports itself. */
} ProcedureMethod;

#define TCLOO_PROCEDURE_METHOD_VERSION 0

/*
 * Flags for use in a ProcedureMethod.
 *
 * When the USE_DECLARER_NS flag is set, the method will use the namespace of
 * the object or class that declared it (or the clone of it, if it was from
 * such that the implementation of the method came to the particular use)
 * instead of the namespace of the object on which the method was invoked.
 * This flag must be distinct from all others that are associated with
 * methods.
 */

#define USE_DECLARER_NS		0x80

/*
 * Forwarded methods have the following extra information.
 */

typedef struct ForwardMethod {
    Tcl_Obj *prefixObj;		/* The list of values to use to replace the
				 * object and method name with. Will be a
				 * non-empty list. */
} ForwardMethod;

/*
 * Helper definitions that declare a "list" array. The two varieties are
 * either optimized for simplicity (in the case that the whole array is
 * typically assigned at once) or efficiency (in the case that the array is
 * expected to be expanded over time). These lists are designed to be iterated
 * over with the help of the FOREACH macro (see later in this file).
 *
 * The "num" field always counts the number of listType_t elements used in the
 * "list" field. When a "size" field exists, it describes how many elements
 * are present in the list; when absent, exactly "num" elements are present.
 */

#define LIST_STATIC(listType_t) \
    struct { int num; listType_t *list; }
#define LIST_DYNAMIC(listType_t) \
    struct { int num, size; listType_t *list; }

/*
 * Now, the definition of what an object actually is.
 */

typedef struct Object {
    struct Foundation *fPtr;	/* The basis for the object system. Putting
				 * this here allows the avoidance of quite a
				 * lot of hash lookups on the critical path
				 * for object invocation and creation. */
    Tcl_Namespace *namespacePtr;/* This object's namespace. */
    Tcl_Command command;	/* Reference to this object's public
				 * command. */
    Tcl_Command myCommand;	/* Reference to this object's internal
				 * command. */
    struct Class *selfCls;	/* This object's class. */
    Tcl_HashTable *methodsPtr;	/* Object-local Tcl_Obj (method name) to
				 * Method* mapping. */
    LIST_STATIC(struct Class *) mixins;
				/* Classes mixed into this object. */
    LIST_STATIC(Tcl_Obj *) filters;
				/* List of filter names. */
    struct Class *classPtr;	/* This is non-NULL for all classes, and NULL
				 *  for everything else. It points to the class
				 *  structure. */
    int refCount;		/* Number of strong references to this object.
				 * Note that there may be many more weak
				 * references; this mechanism exists to
				 * avoid Tcl_Preserve. */
    int flags;
    int creationEpoch;		/* Unique value to make comparisons of objects
				 * easier. */
    int epoch;			/* Per-object epoch, incremented when the way
				 * an object should resolve call chains is
				 * changed. */
    Tcl_HashTable *metadataPtr;	/* Mapping from pointers to metadata type to
				 * the ClientData values that are the values
				 * of each piece of attached metadata. This
				 * field starts out as NULL and is only
				 * allocated if metadata is attached. */
    Tcl_Obj *cachedNameObj;	/* Cache of the name of the object. */
    Tcl_HashTable *chainCache;	/* Place to keep unused contexts. This table
				 * is indexed by method name as Tcl_Obj. */
    Tcl_ObjectMapMethodNameProc *mapMethodNameProc;
				/* Function to allow remapping of method
				 * names. For itcl-ng. */
    LIST_STATIC(Tcl_Obj *) variables;
} Object;

#define OBJECT_DESTRUCTING	1	/* Indicates that an object is being or has
								 *  been destroyed  */
#define DESTRUCTOR_CALLED 2	/* Indicates that evaluation of destructor script for the
							   object has began */
#define OO_UNUSED_4	4	/* No longer used.  */
#define ROOT_OBJECT 0x1000	/* Flag to say that this object is the root of
				 * the class hierarchy and should be treated
				 * specially during teardown. */
#define FILTER_HANDLING 0x2000	/* Flag set when the object is processing a
				 * filter; when set, filters are *not*
				 * processed on the object, preventing nasty
				 * recursive filtering problems. */
#define USE_CLASS_CACHE 0x4000	/* Flag set to say that the object is a pure
				 * instance of the class, and has had nothing
				 * added that changes the dispatch chain (i.e.
				 * no methods, mixins, or filters. */
#define ROOT_CLASS 0x8000	/* Flag to say that this object is the root
				 * class of classes, and should be treated
				 * specially during teardown (and in a few
				 * other spots). */
#define FORCE_UNKNOWN 0x10000	/* States that we are *really* looking up the
				 * unknown method handler at that point. */
#define DONT_DELETE 0x20000	/* Inhibit deletion of this object. */

/*
 * And the definition of a class. Note that every class also has an associated
 * object, through which it is manipulated.
 */

typedef struct Class {
    Object *thisPtr;		/* Reference to the object associated with
				 * this class. */
    int flags;			/* Assorted flags. */
    LIST_STATIC(struct Class *) superclasses;
				/* List of superclasses, used for generation
				 * of method call chains. */
    LIST_DYNAMIC(struct Class *) subclasses;
				/* List of subclasses, used to ensure deletion
				 * of dependent entities happens properly when
				 * the class itself is deleted. */
    LIST_DYNAMIC(Object *) instances;
				/* List of instances, used to ensure deletion
				 * of dependent entities happens properly when
				 * the class itself is deleted. */
    LIST_STATIC(Tcl_Obj *) filters;
				/* List of filter names, used for generation
				 * of method call chains. */
    LIST_STATIC(struct Class *) mixins;
				/* List of mixin classes, used for generation
				 * of method call chains. */
    LIST_DYNAMIC(struct Class *) mixinSubs;
				/* List of classes that this class is mixed
				 * into, used to ensure deletion of dependent
				 * entities happens properly when the class
				 * itself is deleted. */
    Tcl_HashTable classMethods;	/* Hash table of all methods. Hash maps from
				 * the (Tcl_Obj*) method name to the (Method*)
				 * method record. */
    Method *constructorPtr;	/* Method record of the class constructor (if
				 * any). */
    Method *destructorPtr;	/* Method record of the class destructor (if
				 * any). */
    Tcl_HashTable *metadataPtr;	/* Mapping from pointers to metadata type to
				 * the ClientData values that are the values
				 * of each piece of attached metadata. This
				 * field starts out as NULL and is only
				 * allocated if metadata is attached. */
    struct CallChain *constructorChainPtr;
    struct CallChain *destructorChainPtr;
    Tcl_HashTable *classChainCache;
				/* Places where call chains are stored. For
				 * constructors, the class chain is always
				 * used. For destructors and ordinary methods,
				 * the class chain is only used when the
				 * object doesn't override with its own mixins
				 * (and filters and method implementations for
				 * when getting method chains). */
    LIST_STATIC(Tcl_Obj *) variables;
} Class;

/*
 * The foundation of the object system within an interpreter contains
 * references to the key classes and namespaces, together with a few other
 * useful bits and pieces. Probably ought to eventually go in the Interp
 * structure itself.
 */

typedef struct ThreadLocalData {
    int nsCount;		/* Epoch counter is used for keeping
				 * the values used in Tcl_Obj internal
				 * representations sane. Must be thread-local
				 * because Tcl_Objs can cross interpreter
				 * boundaries within a thread (objects don't
				 * generally cross threads). */
} ThreadLocalData;

typedef struct Foundation {
    Tcl_Interp *interp;
    Class *objectCls;		/* The root of the object system. */
    Class *classCls;		/* The class of all classes. */
    Tcl_Namespace *ooNs;	/* ::oo namespace. */
    Tcl_Namespace *defineNs;	/* Namespace containing special commands for
				 * manipulating objects and classes. The
				 * "oo::define" command acts as a special kind
				 * of ensemble for this namespace. */
    Tcl_Namespace *objdefNs;	/* Namespace containing special commands for
				 * manipulating objects and classes. The
				 * "oo::objdefine" command acts as a special
				 * kind of ensemble for this namespace. */
    Tcl_Namespace *helpersNs;	/* Namespace containing the commands that are
				 * only valid when executing inside a
				 * procedural method. */
    int epoch;			/* Used to invalidate method chains when the
				 * class structure changes. */
    ThreadLocalData *tsdPtr;	/* Counter so we can allocate a unique
				 * namespace to each object. */
    Tcl_Obj *unknownMethodNameObj;
				/* Shared object containing the name of the
				 * unknown method handler method. */
    Tcl_Obj *constructorName;	/* Shared object containing the "name" of a
				 * constructor. */
    Tcl_Obj *destructorName;	/* Shared object containing the "name" of a
				 * destructor. */
    Tcl_Obj *clonedName;	/* Shared object containing the name of a
				 * "<cloned>" pseudo-constructor. */
    Tcl_Obj *defineName;	/* Fully qualified name of oo::define. */
} Foundation;

/*
 * A call context structure is built when a method is called. It contains the
 * chain of method implementations that are to be invoked by a particular
 * call, and the process of calling walks the chain, with the [next] command
 * proceeding to the next entry in the chain.
 */

#define CALL_CHAIN_STATIC_SIZE 4

struct MInvoke {
    Method *mPtr;		/* Reference to the method implementation
				 * record. */
    int isFilter;		/* Whether this is a filter invocation. */
    Class *filterDeclarer;	/* What class decided to add the filter; if
				 * NULL, it was added by the object. */
};

typedef struct CallChain {
    int objectCreationEpoch;	/* The object's creation epoch. Note that the
				 * object reference is not stored in the call
				 * chain; it is in the call context. */
    int objectEpoch;		/* Local (object structure) epoch counter
				 * snapshot. */
    int epoch;			/* Global (class structure) epoch counter
				 * snapshot. */
    int flags;			/* Assorted flags, see below. */
    int refCount;		/* Reference count. */
    int numChain;		/* Size of the call chain. */
    struct MInvoke *chain;	/* Array of call chain entries. May point to
				 * staticChain if the number of entries is
				 * small. */
    struct MInvoke staticChain[CALL_CHAIN_STATIC_SIZE];
} CallChain;

typedef struct CallContext {
    Object *oPtr;		/* The object associated with this call. */
    int index;			/* Index into the call chain of the currently
				 * executing method implementation. */
    int skip;			/* Current number of arguments to skip; can
				 * vary depending on whether it is a direct
				 * method call or a continuation via the
				 * [next] command. */
    CallChain *callPtr;		/* The actual call chain. */
} CallContext;

/*
 * Bits for the 'flags' field of the call chain.
 */

#define PUBLIC_METHOD     0x01	/* This is a public (exported) method. */
#define PRIVATE_METHOD    0x02	/* This is a private (class's direct instances
				 * only) method. */
#define OO_UNKNOWN_METHOD 0x04	/* This is an unknown method. */
#define CONSTRUCTOR	  0x08	/* This is a constructor. */
#define DESTRUCTOR	  0x10	/* This is a destructor. */

/*
 * Structure containing definition information about basic class methods.
 */

typedef struct {
    const char *name;		/* Name of the method in question. */
    int isPublic;		/* Whether the method is public by default. */
    Tcl_MethodType definition;	/* How to call the method. */
} DeclaredClassMethod;
