Implementation of TIP #257. Incomplete due to missing Win build support.

1 files changed, 579 insertions, 0 deletions

diff --git a/generic/tclOOInt.h b/generic/tclOOInt.h
new file mode 100644
index 0000000..7c0b6a7
--- /dev/null
+++ b/generic/tclOOInt.h
@@ -0,0 +1,579 @@
+/*
+ * 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 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.
+ *
+ * RCS: @(#) $Id: tclOOInt.h,v 1.1 2008/05/31 11:42:18 dkf Exp $
+ */
+
+#include <tclInt.h>
+#include "tclOO.h"
+
+/*
+ * 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. It is a
+ * single-field structure because this allows for future expansion without
+ * changing vast amounts of code.
+ */
+
+typedef struct ForwardMethod {
+    Tcl_Obj *prefixObj;
+} 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 invokation and creation. */
+    Tcl_Namespace *namespacePtr;/* This object's tame 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;	/* All classes have this non-NULL; it points
+				 * to the class structure. Everything else has
+				 * this NULL. */
+    int refCount;		/* Number of strong references to this object.
+				 * Note that there may be many more weak
+				 * references; this mechanism is there 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. */
+} Object;
+
+#define OBJECT_DELETED	1	/* Flag to say that an object has been
+				 * destroyed. */
+#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. */
+
+/*
+ * 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 refCount;		/* Number of strong references to this class.
+				 * Weak references are not counted; the
+				 * purpose of this is to avoid Tcl_Preserve as
+				 * that is quite slow. */
+    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). */
+} 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;		/* Master 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;	/* Master ::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. */
+} Foundation;
+
+/*
+ * A call context structure is built when a method is called. They contain 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 invokation. */
+    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 context.
+ */
+
+#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. */
+
+/*
+ * Assorted flags for call frames. Note that bits 1 and 2 are already taken by
+ * Tcl itself.
+ */
+
+#if 0
+#define FRAME_IS_METHOD	0x4	/* The frame is a method body, and the frame's
+				 * clientData field contains a CallContext
+				 * reference. */
+#define FRAME_IS_OO_DEFINE 0x8	/* The frame is part of the inside workings of
+				 * the [oo::define] command; the clientData
+				 * field contains an Object reference that has
+				 * been confirmed to refer to a class. */
+#endif
+
+/*
+ * 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;
+
+/*
+ *----------------------------------------------------------------
+ * Commands relating to OO support.
+ *----------------------------------------------------------------
+ */
+
+MODULE_SCOPE int	TclOOInit(Tcl_Interp *interp);
+MODULE_SCOPE int	TclOODefineObjCmd(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOOObjDefObjCmd(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOODefineConstructorObjCmd(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOODefineDeleteMethodObjCmd(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOODefineDestructorObjCmd(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOODefineExportObjCmd(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOODefineFilterObjCmd(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOODefineForwardObjCmd(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOODefineMethodObjCmd(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOODefineMixinObjCmd(ClientData clientData,
+			    Tcl_Interp *interp, const int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOODefineRenameMethodObjCmd(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOODefineSuperclassObjCmd(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOODefineUnexportObjCmd(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOODefineClassObjCmd(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOODefineSelfObjCmd(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOOUnknownDefinition(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOOCopyObjectCmd(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOONextObjCmd(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOOSelfObjCmd(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const *objv);
+
+/*
+ * Method implementations (in tclOOBasic.c).
+ */
+
+MODULE_SCOPE int	TclOO_Class_Create(ClientData clientData,
+			    Tcl_Interp *interp, Tcl_ObjectContext context,
+			    int objc, Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOO_Class_CreateNs(ClientData clientData,
+			    Tcl_Interp *interp, Tcl_ObjectContext context,
+			    int objc, Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOO_Class_New(ClientData clientData,
+			    Tcl_Interp *interp, Tcl_ObjectContext context,
+			    int objc, Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOO_Object_Destroy(ClientData clientData,
+			    Tcl_Interp *interp, Tcl_ObjectContext context,
+			    int objc, Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOO_Object_Eval(ClientData clientData,
+			    Tcl_Interp *interp, Tcl_ObjectContext context,
+			    int objc, Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOO_Object_LinkVar(ClientData clientData,
+			    Tcl_Interp *interp, Tcl_ObjectContext context,
+			    int objc, Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOO_Object_Unknown(ClientData clientData,
+			    Tcl_Interp *interp, Tcl_ObjectContext context,
+			    int objc, Tcl_Obj *const *objv);
+MODULE_SCOPE int	TclOO_Object_VarName(ClientData clientData,
+			    Tcl_Interp *interp, Tcl_ObjectContext context,
+			    int objc, Tcl_Obj *const *objv);
+
+/*
+ * Private definitions, some of which perhaps ought to be exposed properly or
+ * maybe just put in the internal stubs table.
+ */
+
+MODULE_SCOPE void	TclOOAddToInstances(Object *oPtr, Class *clsPtr);
+MODULE_SCOPE void	TclOOAddToMixinSubs(Class *subPtr, Class *mixinPtr);
+MODULE_SCOPE void	TclOOAddToSubclasses(Class *subPtr, Class *superPtr);
+MODULE_SCOPE void	TclOODeleteChain(CallChain *callPtr);
+MODULE_SCOPE void	TclOODeleteChainCache(Tcl_HashTable *tablePtr);
+MODULE_SCOPE void	TclOODeleteContext(CallContext *contextPtr);
+MODULE_SCOPE void	TclOODelMethodRef(Method *method);
+MODULE_SCOPE CallContext *TclOOGetCallContext(Object *oPtr,
+			    Tcl_Obj *methodNameObj, int flags);
+MODULE_SCOPE Foundation	*TclOOGetFoundation(Tcl_Interp *interp);
+MODULE_SCOPE Tcl_Obj *	TclOOGetFwdFromMethod(Method *mPtr);
+MODULE_SCOPE Proc *	TclOOGetProcFromMethod(Method *mPtr);
+MODULE_SCOPE int	TclOOGetSortedClassMethodList(Class *clsPtr,
+			    int flags, const char ***stringsPtr);
+MODULE_SCOPE int	TclOOGetSortedMethodList(Object *oPtr, int flags,
+			    const char ***stringsPtr);
+MODULE_SCOPE int	TclOOInit(Tcl_Interp *interp);
+MODULE_SCOPE void	TclOOInitInfo(Tcl_Interp *interp);
+MODULE_SCOPE int	TclOOInvokeContext(Tcl_Interp *interp,
+			    CallContext *contextPtr, int objc,
+			    Tcl_Obj *const *objv);
+MODULE_SCOPE void	TclOONewBasicMethod(Tcl_Interp *interp, Class *clsPtr,
+			    const DeclaredClassMethod *dcm);
+MODULE_SCOPE Tcl_Obj *	TclOOObjectName(Tcl_Interp *interp, Object *oPtr);
+MODULE_SCOPE void	TclOORemoveFromInstances(Object *oPtr, Class *clsPtr);
+MODULE_SCOPE void	TclOORemoveFromMixinSubs(Class *subPtr,
+			    Class *mixinPtr);
+MODULE_SCOPE void	TclOORemoveFromSubclasses(Class *subPtr,
+			    Class *superPtr);
+MODULE_SCOPE void	TclOOStashContext(Tcl_Obj *objPtr,
+			    CallContext *contextPtr);
+
+/*
+ * Include all the private API, generated from tclOO.decls.
+ */
+
+#include "tclOOIntDecls.h"
+
+/*
+ * A convenience macro for iterating through the lists used in the internal
+ * memory management of objects. This is a bit gnarly because we want to do
+ * the assignment of the picked-out value only when the body test succeeds,
+ * but we cannot rely on the assigned value being useful, forcing us to do
+ * some nasty stuff with the comma operator. The compiler's optimizer should
+ * be able to sort it all out!
+ *
+ * REQUIRES DECLARATION: int i;
+ */
+
+#define FOREACH(var,ary) \
+	for(i=0 ; (i<(ary).num?((var=(ary).list[i]),1):0) ; i++)
+
+/*
+ * Convenience macros for iterating through hash tables. FOREACH_HASH_DECLS
+ * sets up the declarations needed for the main macro, FOREACH_HASH, which
+ * does the actual iteration. FOREACH_HASH_VALUE is a restricted version that
+ * only iterates over values.
+ */
+
+#define FOREACH_HASH_DECLS \
+    Tcl_HashEntry *hPtr;Tcl_HashSearch search
+#define FOREACH_HASH(key,val,tablePtr) \
+    for(hPtr=Tcl_FirstHashEntry((tablePtr),&search); hPtr!=NULL ? \
+	    ((key)=(void *)Tcl_GetHashKey((tablePtr),hPtr),\
+	    (val)=Tcl_GetHashValue(hPtr),1):0; hPtr=Tcl_NextHashEntry(&search))
+#define FOREACH_HASH_VALUE(val,tablePtr) \
+    for(hPtr=Tcl_FirstHashEntry((tablePtr),&search); hPtr!=NULL ? \
+	    ((val)=Tcl_GetHashValue(hPtr),1):0;hPtr=Tcl_NextHashEntry(&search))
+
+/*
+ * Convenience macro for duplicating a list. Needs no external declaration,
+ * but all arguments are used multiple times and so must have no side effects.
+ */
+
+#define DUPLICATE(target,source,type) \
+    do { \
+	register unsigned len = sizeof(type) * ((target).num=(source).num);\
+	if (len != 0) { \
+	    memcpy(((target).list=(type*)ckalloc(len)), (source).list, len); \
+	} else { \
+	    (target).list = NULL; \
+	} \
+    } while(0)
+
+/*
+ * Alternatives to Tcl_Preserve/Tcl_EventuallyFree/Tcl_Release.
+ */
+
+#define AddRef(ptr) ((ptr)->refCount++)
+#define DelRef(ptr) do {			\
+	if (--(ptr)->refCount < 1) {		\
+	    ckfree((char *) (ptr));		\
+	}					\
+    } while(0)
+
+/*
+ * Local Variables:
+ * mode: c
+ * c-basic-offset: 4
+ * fill-column: 78
+ * End:
+ */