/* 
 * tclDictObj.c --
 *
 *	This file contains procedures that implement the Tcl dict object
 *	type and its accessor command.
 *
 * Copyright (c) 2002 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: tclDictObj.c,v 1.2 2003/04/05 01:41:23 dkf Exp $
 */

#include "tclInt.h"

/*
 * Prototypes for procedures defined later in this file:
 */

static int		DictAppendCmd _ANSI_ARGS_((Tcl_Interp *interp,
			    int objc, Tcl_Obj *CONST *objv));
static int		DictCreateCmd _ANSI_ARGS_((Tcl_Interp *interp,
			    int objc, Tcl_Obj *CONST *objv));
static int		DictExistsCmd _ANSI_ARGS_((Tcl_Interp *interp,
			    int objc, Tcl_Obj *CONST *objv));
static int		DictFilterCmd _ANSI_ARGS_((Tcl_Interp *interp,
			    int objc, Tcl_Obj *CONST *objv));
static int		DictForCmd _ANSI_ARGS_((Tcl_Interp *interp,
			    int objc, Tcl_Obj *CONST *objv));
static int		DictGetCmd _ANSI_ARGS_((Tcl_Interp *interp,
			    int objc, Tcl_Obj *CONST *objv));
static int		DictIncrCmd _ANSI_ARGS_((Tcl_Interp *interp,
			    int objc, Tcl_Obj *CONST *objv));
static int		DictInfoCmd _ANSI_ARGS_((Tcl_Interp *interp,
			    int objc, Tcl_Obj *CONST *objv));
static int		DictKeysCmd _ANSI_ARGS_((Tcl_Interp *interp,
			    int objc, Tcl_Obj *CONST *objv));
static int		DictLappendCmd _ANSI_ARGS_((Tcl_Interp *interp,
			    int objc, Tcl_Obj *CONST *objv));
static int		DictRemoveCmd _ANSI_ARGS_((Tcl_Interp *interp,
			    int objc, Tcl_Obj *CONST *objv));
static int		DictReplaceCmd _ANSI_ARGS_((Tcl_Interp *interp,
			    int objc, Tcl_Obj *CONST *objv));
static int		DictSetCmd _ANSI_ARGS_((Tcl_Interp *interp,
			    int objc, Tcl_Obj *CONST *objv));
static int		DictSizeCmd _ANSI_ARGS_((Tcl_Interp *interp,
			    int objc, Tcl_Obj *CONST *objv));
static int		DictUnsetCmd _ANSI_ARGS_((Tcl_Interp *interp,
			    int objc, Tcl_Obj *CONST *objv));
static int		DictValuesCmd _ANSI_ARGS_((Tcl_Interp *interp,
			    int objc, Tcl_Obj *CONST *objv));
static void		DupDictInternalRep _ANSI_ARGS_((Tcl_Obj *srcPtr,
			    Tcl_Obj *copyPtr));
static void		FreeDictInternalRep _ANSI_ARGS_((Tcl_Obj *dictPtr));
static int		SetDictFromAny _ANSI_ARGS_((Tcl_Interp *interp,
			    Tcl_Obj *objPtr));
static void		UpdateStringOfDict _ANSI_ARGS_((Tcl_Obj *dictPtr));
static Tcl_Obj *	TraceDictPath _ANSI_ARGS_((Tcl_Interp *interp,
			    Tcl_Obj *rootPtr, int keyc, Tcl_Obj *CONST keyv[],
			    int willUpdate));
struct Dict;
static void		DeleteDict _ANSI_ARGS_((struct Dict *dict));

/*
 * Internal representation of a dictionary.
 *
 * The internal representation of a dictionary object is a hash table
 * (with Tcl_Objs for both keys and values), a reference count and
 * epoch number for detecting concurrent modifications of the
 * dictionary, and a pointer to the parent object (used when
 * invalidating string reps of pathed dictionary trees) which is NULL
 * in normal use.  The fact that hash tables know (with appropriate
 * initialisation) already about objects makes key management /so/
 * much easier!
 *
 * Reference counts are used to enable safe iteration across hashes
 * while allowing the type of the containing object to be modified.
 */

typedef struct Dict {
    Tcl_HashTable table;
    int epoch;
    int refcount;
    Tcl_Obj *chain;
} Dict;

/*
 * The structure below defines the dictionary object type by means of
 * procedures that can be invoked by generic object code.
 */

Tcl_ObjType tclDictType = {
    "dict",
    FreeDictInternalRep,		/* freeIntRepProc */
    DupDictInternalRep,		        /* dupIntRepProc */
    UpdateStringOfDict,			/* updateStringProc */
    SetDictFromAny			/* setFromAnyProc */
};

/*
 *----------------------------------------------------------------------
 *
 * DupDictInternalRep --
 *
 *	Initialize the internal representation of a dictionary Tcl_Obj
 *	to a copy of the internal representation of an existing
 *	dictionary object. 
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	"srcPtr"s dictionary internal rep pointer should not be NULL and
 *	we assume it is not NULL. We set "copyPtr"s internal rep to a
 *	pointer to a newly allocated dictionary rep that, in turn, points
 *	to "srcPtr"s key and value objects. Those objects are not
 *	actually copied but are shared between "srcPtr" and "copyPtr".
 *	The ref count of each key and value object is incremented.
 *
 *----------------------------------------------------------------------
 */

static void
DupDictInternalRep(srcPtr, copyPtr)
    Tcl_Obj *srcPtr, *copyPtr;
{
    Dict *oldDict = (Dict *) srcPtr->internalRep.otherValuePtr;
    Dict *newDict = (Dict *) ckalloc(sizeof(Dict));
    Tcl_HashEntry *hPtr, *newHPtr;
    Tcl_HashSearch search;
    Tcl_Obj *keyPtr, *valuePtr;
    int isNew;

    /*
     * Copy values across from the old hash table.
     */
    Tcl_InitObjHashTable(&newDict->table);
    for (hPtr=Tcl_FirstHashEntry(&oldDict->table,&search); hPtr!=NULL;
	    hPtr=Tcl_NextHashEntry(&search)) {
	keyPtr = (Tcl_Obj *) Tcl_GetHashKey(&oldDict->table, hPtr);
	valuePtr = (Tcl_Obj *) Tcl_GetHashValue(hPtr);
	newHPtr = Tcl_CreateHashEntry(&newDict->table, (char *)keyPtr, &isNew);
	Tcl_SetHashValue(newHPtr, (ClientData)valuePtr);
	Tcl_IncrRefCount(valuePtr);
    }

    /*
     * Initialise other fields.
     */
    newDict->epoch = 0;
    newDict->chain = NULL;
    newDict->refcount = 1;

    /*
     * Store in the object.
     */
    copyPtr->internalRep.otherValuePtr = (VOID *) newDict;
    copyPtr->typePtr = &tclDictType;
}

/*
 *----------------------------------------------------------------------
 *
 * FreeDictInternalRep --
 *
 *	Deallocate the storage associated with a dictionary object's
 *	internal representation.
 *
 * Results:
 *	None
 *
 * Side effects:
 *	Frees the memory holding the dictionary's internal hash table.
 *	Decrements the reference count of all key and value objects,
 *	which may free them.
 *
 *----------------------------------------------------------------------
 */

static void
FreeDictInternalRep(dictPtr)
    Tcl_Obj *dictPtr;
{
    Dict *dict = (Dict *) dictPtr->internalRep.otherValuePtr;

    --dict->refcount;
    if (dict->refcount == 0) {
	DeleteDict(dict);
    }

    dictPtr->internalRep.otherValuePtr = NULL;	/* Belt and braces! */
}

static void
DeleteDict(dict)
    Dict *dict;
{
    Tcl_HashEntry *hPtr;
    Tcl_HashSearch search;
    Tcl_Obj *valuePtr;

    /*
     * Delete the values ourselves, because hashes know nothing about
     * their contents (but do know about the key type, so that doesn't
     * need explicit attention.)
     */
    for (hPtr=Tcl_FirstHashEntry(&dict->table,&search); hPtr!=NULL;
	    hPtr=Tcl_NextHashEntry(&search)) {
	valuePtr = (Tcl_Obj *) Tcl_GetHashValue(hPtr);
	Tcl_DecrRefCount(valuePtr);
    }
    Tcl_DeleteHashTable(&dict->table);
    ckfree((char *) dict);
}

/*
 *----------------------------------------------------------------------
 *
 * UpdateStringOfDict --
 *
 *	Update the string representation for a dictionary object.
 *	Note: This procedure does not invalidate an existing old string
 *	rep so storage will be lost if this has not already been done.
 *	This code is based on UpdateStringOfList in tclListObj.c
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The object's string is set to a valid string that results from
 *	the dict-to-string conversion. This string will be empty if the
 *	dictionary has no key/value pairs. The dictionary internal
 *	representation should not be NULL and we assume it is not NULL.
 *
 *----------------------------------------------------------------------
 */

static void
UpdateStringOfDict(dictPtr)
    Tcl_Obj *dictPtr;
{
#define LOCAL_SIZE 20
    int localFlags[LOCAL_SIZE], *flagPtr;
    Dict *dict = (Dict *) dictPtr->internalRep.otherValuePtr;
    Tcl_HashEntry *hPtr;
    Tcl_HashSearch search;
    Tcl_Obj *keyPtr, *valuePtr;
    int numElems, i, length;
    char *elem, *dst;

    /*
     * This field is the most useful one in the whole hash structure,
     * and it is not exposed by any API function...
     */
    numElems = dict->table.numEntries * 2;

    /*
     * Pass 1: estimate space, gather flags.
     */

    if (numElems <= LOCAL_SIZE) {
	flagPtr = localFlags;
    } else {
	flagPtr = (int *) ckalloc((unsigned) numElems*sizeof(int));
    }
    dictPtr->length = 1;
    for (i=0,hPtr=Tcl_FirstHashEntry(&dict->table,&search) ; i<numElems ;
	    i+=2,hPtr=Tcl_NextHashEntry(&search)) {
	/*
	 * Assume that hPtr is never NULL since we know the number of
	 * array elements already.
	 */

	keyPtr = (Tcl_Obj *) Tcl_GetHashKey(&dict->table, hPtr);
	elem = Tcl_GetStringFromObj(keyPtr, &length);
	dictPtr->length += Tcl_ScanCountedElement(elem, length,
		&flagPtr[i]) + 1;

	valuePtr = (Tcl_Obj *) Tcl_GetHashValue(hPtr);
	elem = Tcl_GetStringFromObj(valuePtr, &length);
	dictPtr->length += Tcl_ScanCountedElement(elem, length,
		&flagPtr[i+1]) + 1;
    }

    /*
     * Pass 2: copy into string rep buffer.
     */

    dictPtr->bytes = ckalloc((unsigned) dictPtr->length);
    dst = dictPtr->bytes;
    for (i=0,hPtr=Tcl_FirstHashEntry(&dict->table,&search) ; i<numElems ;
	    i+=2,hPtr=Tcl_NextHashEntry(&search)) {
	keyPtr = (Tcl_Obj *) Tcl_GetHashKey(&dict->table, hPtr);
	elem = Tcl_GetStringFromObj(keyPtr, &length);
	dst += Tcl_ConvertCountedElement(elem, length, dst, flagPtr[i]);
	*(dst++) = ' ';

	valuePtr = (Tcl_Obj *) Tcl_GetHashValue(hPtr);
	elem = Tcl_GetStringFromObj(valuePtr, &length);
	dst += Tcl_ConvertCountedElement(elem, length, dst, flagPtr[i+1]);
	*(dst++) = ' ';
    }
    if (flagPtr != localFlags) {
	ckfree((char *) flagPtr);
    }
    if (dst == dictPtr->bytes) {
	*dst = 0;
    } else {
	*(--dst) = 0;
    }
    dictPtr->length = dst - dictPtr->bytes;
}

/*
 *----------------------------------------------------------------------
 *
 * SetDictFromAny --
 *
 *	Convert a non-dictionary object into a dictionary object.  This
 *	code is very closely related to SetListFromAny in tclListObj.c
 *	but does not actually guarantee that a dictionary object will
 *	have a string rep (as conversions from lists are handled with a
 *	special case.)
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	If the string can be converted, it loses any old internal
 *	representation that it had and gains a dictionary's internalRep.
 *
 *----------------------------------------------------------------------
 */

static int
SetDictFromAny(interp, objPtr)
    Tcl_Interp *interp;
    Tcl_Obj *objPtr;
{
    Tcl_ObjType *oldTypePtr = objPtr->typePtr;
    char *string, *s;
    CONST char *elemStart, *nextElem;
    int lenRemain, length, elemSize, hasBrace, result, isNew;
    char *limit;		/* Points just after string's last byte. */
    register CONST char *p;
    register Tcl_Obj *keyPtr, *valuePtr;
    Dict *dict;
    Tcl_HashEntry *hPtr;
    Tcl_HashSearch search;

    /*
     * Since lists and dictionaries have very closely-related string
     * representations (i.e. the same parsing code) we can safely
     * special-case the conversion from lists to dictionaries.
     */

    if (oldTypePtr == &tclListType) {
	int objc, i;
	Tcl_Obj **objv;

	if (Tcl_ListObjGetElements(interp, objPtr, &objc, &objv) != TCL_OK) {
	    return TCL_ERROR;
	}
	if (objc & 1) {
	    if (interp != NULL) {
		Tcl_SetObjResult(interp,
			Tcl_NewStringObj("missing value to go with key", -1));
	    }
	    return TCL_ERROR;
	}

	/*
	 * Build the hash of key/value pairs.
	 */
	dict = (Dict *) ckalloc(sizeof(Dict));
	Tcl_InitObjHashTable(&dict->table);
	for (i=0 ; i<objc ; i+=2) {
	    /*
	     * Store key and value in the hash table we're building.
	     */

	    hPtr = Tcl_CreateHashEntry(&dict->table, (char *)objv[i], &isNew);
	    if (!isNew) {
		Tcl_Obj *discardedValue = (Tcl_Obj *) Tcl_GetHashValue(hPtr);
		Tcl_DecrRefCount(discardedValue);
	    }
	    Tcl_SetHashValue(hPtr, (ClientData) objv[i+1]);
	    Tcl_IncrRefCount(objv[i+1]); /* since hash now holds ref to it */
	}

	/*
	 * Share type-setting code with the string-conversion case.
	 */
	goto installHash;
    }

    /*
     * Get the string representation. Make it up-to-date if necessary.
     */

    string = Tcl_GetStringFromObj(objPtr, &length);
    limit = (string + length);

    /*
     * Allocate a new HashTable that has objects for keys and objects
     * for values.
     */

    dict = (Dict *) ckalloc(sizeof(Dict));
    Tcl_InitObjHashTable(&dict->table);
    for (p = string, lenRemain = length;
	    lenRemain > 0;
	    p = nextElem, lenRemain = (limit - nextElem)) {
	result = TclFindElement(interp, p, lenRemain,
		&elemStart, &nextElem, &elemSize, &hasBrace);
	if (result != TCL_OK) {
	    goto errorExit;
	}
	if (elemStart >= limit) {
	    break;
	}

	/*
	 * Allocate a Tcl object for the element and initialize it from the
	 * "elemSize" bytes starting at "elemStart".
	 */

	s = ckalloc((unsigned) elemSize + 1);
	if (hasBrace) {
	    memcpy((VOID *) s, (VOID *) elemStart,  (size_t) elemSize);
	    s[elemSize] = 0;
	} else {
	    elemSize = TclCopyAndCollapse(elemSize, elemStart, s);
	}
	
	TclNewObj(keyPtr);
        keyPtr->bytes  = s;
        keyPtr->length = elemSize;

	p = nextElem;
	lenRemain = (limit - nextElem);
	if (lenRemain <= 0) {
	    goto missingKey;
	}

	result = TclFindElement(interp, p, lenRemain,
		&elemStart, &nextElem, &elemSize, &hasBrace);
	if (result != TCL_OK) {
	    Tcl_DecrRefCount(keyPtr);
	    goto errorExit;
	}
	if (elemStart >= limit) {
	    goto missingKey;
	}

	/*
	 * Allocate a Tcl object for the element and initialize it from the
	 * "elemSize" bytes starting at "elemStart".
	 */

	s = ckalloc((unsigned) elemSize + 1);
	if (hasBrace) {
	    memcpy((VOID *) s, (VOID *) elemStart,  (size_t) elemSize);
	    s[elemSize] = 0;
	} else {
	    elemSize = TclCopyAndCollapse(elemSize, elemStart, s);
	}

	TclNewObj(valuePtr);
        valuePtr->bytes  = s;
        valuePtr->length = elemSize;

	/*
	 * Store key and value in the hash table we're building.
	 */
	hPtr = Tcl_CreateHashEntry(&dict->table, (char *)keyPtr, &isNew);
	if (!isNew) {
	    Tcl_Obj *discardedValue = (Tcl_Obj *) Tcl_GetHashValue(hPtr);
	    Tcl_DecrRefCount(keyPtr);
	    Tcl_DecrRefCount(discardedValue);
	}
	Tcl_SetHashValue(hPtr, (ClientData) valuePtr);
	Tcl_IncrRefCount(valuePtr); /* since hash now holds ref to it */
    }

 installHash:
    /*
     * Free the old internalRep before setting the new one. We do this as
     * late as possible to allow the conversion code, in particular
     * Tcl_GetStringFromObj, to use that old internalRep.
     */

    if ((oldTypePtr != NULL) && (oldTypePtr->freeIntRepProc != NULL)) {
	oldTypePtr->freeIntRepProc(objPtr);
    }

    dict->epoch = 0;
    dict->chain = NULL;
    dict->refcount = 1;
    objPtr->internalRep.otherValuePtr = (VOID *) dict;
    objPtr->typePtr = &tclDictType;
    return TCL_OK;

 missingKey:
    if (interp != NULL) {
	Tcl_SetObjResult(interp,
		Tcl_NewStringObj("missing value to go with key", -1));
    }
    Tcl_DecrRefCount(keyPtr);
    result = TCL_ERROR;
 errorExit:
    for (hPtr=Tcl_FirstHashEntry(&dict->table,&search);
	   hPtr!=NULL ; hPtr=Tcl_NextHashEntry(&search)) {
	valuePtr = (Tcl_Obj *) Tcl_GetHashValue(hPtr);
	Tcl_DecrRefCount(valuePtr);
    }
    Tcl_DeleteHashTable(&dict->table);
    ckfree((char *) dict);
    return result;
}

/*
 *----------------------------------------------------------------------
 *
 * TraceDictPath --
 *
 *	Trace through a tree of dictionaries using the array of keys
 *	given. If the willUpdate flag is set, a backward-pointing chain
 *	of dictionaries is also built (in the Dict's chain field) and
 *	the chained dictionaries are made into unshared dictionaries (if
 *	they aren't already.)
 *
 * Results:
 *	The object at the end of the path, or NULL if there was an error.
 *	Note that this it is an error for an intermediate dictionary on
 *	the path to not exist.
 *
 * Side effects:
 *	If the willUpdate flag is false, there are no side effects (other
 *	than potential conversion of objects to dictionaries.)  If the
 *	willUpdate flag is true, the following additional side effects
 *	occur.  Shared dictionaries along the path are converted into
 *	unshared objects, and a backward-pointing chain is built using
 *	the chain fields of the dictionaries (for easy invalidation of
 *	string representations.)
 *
 *----------------------------------------------------------------------
 */

static Tcl_Obj *
TraceDictPath(interp, dictPtr, keyc, keyv, willUpdate)
    Tcl_Interp *interp;
    Tcl_Obj *dictPtr, *CONST keyv[];
    int keyc, willUpdate;
{
    Dict *dict, *newDict;
    int i;

    if (dictPtr->typePtr != &tclDictType) {
	if (SetDictFromAny(interp, dictPtr) != TCL_OK) {
	    return NULL;
	}
    }
    dict = (Dict *) dictPtr->internalRep.otherValuePtr;
    if (willUpdate) {
	dict->chain = NULL;
    }

    for (i=0 ; i<keyc ; i++) {
	Tcl_HashEntry *hPtr = Tcl_FindHashEntry(&dict->table, (char *)keyv[i]);
	Tcl_Obj *tmpObj;

	if (hPtr == NULL) {
	    if (interp != NULL) {
		Tcl_ResetResult(interp);
		Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
			"key \"", TclGetString(keyv[i]),
			"\" not known in dictionary", NULL);
	    }
	    return NULL;
	}

	tmpObj = (Tcl_Obj *) Tcl_GetHashValue(hPtr);
	if (tmpObj->typePtr != &tclDictType) {
	    if (SetDictFromAny(interp, tmpObj) != TCL_OK) {
		return NULL;
	    }
	}
	newDict = (Dict *) tmpObj->internalRep.otherValuePtr;
	if (willUpdate) {
	    if (Tcl_IsShared(tmpObj)) {
		Tcl_DecrRefCount(tmpObj);
		tmpObj = Tcl_DuplicateObj(tmpObj);
		Tcl_SetHashValue(hPtr, (ClientData) tmpObj);
		dict->epoch++;
		newDict = (Dict *) tmpObj->internalRep.otherValuePtr;
	    }

	    newDict->chain = dictPtr;
	}
	dict = newDict;
	dictPtr = tmpObj;
    }
    return dictPtr;
}
static void
InvalidateDictChain(dictObj)
    Tcl_Obj *dictObj;
{
    Dict *dict = (Dict *) dictObj->internalRep.otherValuePtr;

    do {
	if (dictObj->bytes != NULL) {
	    Tcl_InvalidateStringRep(dictObj);
	}
	dict->epoch++;
	if ((dictObj = dict->chain) == NULL) {
	    break;
	}
	dict->chain = NULL;
	dict = (Dict *) dictObj->internalRep.otherValuePtr;
    } while (dict != NULL);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_DictObjPut --
 *
 *	Add a key,value pair to a dictionary, or update the value for a
 *	key if that key already has a mapping in the dictionary.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	The object pointed to by dictPtr is converted to a dictionary if
 *	it is not already one, and any string representation that it has
 *	is invalidated.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_DictObjPut(interp, dictPtr, keyPtr, valuePtr)
    Tcl_Interp *interp;
    Tcl_Obj *dictPtr, *keyPtr, *valuePtr;
{
    Dict *dict;
    Tcl_HashEntry *hPtr;
    int isNew;

    if (Tcl_IsShared(dictPtr)) {
	panic("Tcl_DictObjPut called with shared object");
    }

    if (dictPtr->typePtr != &tclDictType) {
	int result = SetDictFromAny(interp, dictPtr);
	if (result != TCL_OK) {
	    return result;
	}
    }

    if (dictPtr->bytes != NULL) {
	Tcl_InvalidateStringRep(dictPtr);
    }
    dict = (Dict *) dictPtr->internalRep.otherValuePtr;
    hPtr = Tcl_CreateHashEntry(&dict->table, (char *)keyPtr, &isNew);
    Tcl_IncrRefCount(valuePtr);
    if (!isNew) {
	Tcl_Obj *oldValuePtr = (Tcl_Obj *) Tcl_GetHashValue(hPtr);
	Tcl_DecrRefCount(oldValuePtr);
    }
    Tcl_SetHashValue(hPtr, valuePtr);
    dict->epoch++;
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_DictObjGet --
 *
 *	Given a key, get its value from the dictionary (or NULL if key
 *	is not found in dictionary.)
 *
 * Results:
 *	A standard Tcl result.  The variable pointed to by valuePtrPtr
 *	is updated with the value for the key.  Note that it is not an
 *	error for the key to have no mapping in the dictionary.
 *
 * Side effects:
 *	The object pointed to by dictPtr is converted to a dictionary if
 *	it is not already one.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_DictObjGet(interp, dictPtr, keyPtr, valuePtrPtr)
    Tcl_Interp *interp;
    Tcl_Obj *dictPtr, *keyPtr, **valuePtrPtr;
{
    Dict *dict;
    Tcl_HashEntry *hPtr;

    if (dictPtr->typePtr != &tclDictType) {
	int result = SetDictFromAny(interp, dictPtr);
	if (result != TCL_OK) {
	    return result;
	}
    }

    dict = (Dict *) dictPtr->internalRep.otherValuePtr;
    hPtr = Tcl_FindHashEntry(&dict->table, (char *)keyPtr);
    if (hPtr == NULL) {
	*valuePtrPtr = NULL;
    } else {
	*valuePtrPtr = (Tcl_Obj *) Tcl_GetHashValue(hPtr);
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_DictObjRemove --
 *
 *	Remove the key,value pair with the given key from the dictionary;
 *	the key does not need to be present in the dictionary.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	The object pointed to by dictPtr is converted to a dictionary if
 *	it is not already one, and any string representation that it has
 *	is invalidated.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_DictObjRemove(interp, dictPtr, keyPtr)
    Tcl_Interp *interp;
    Tcl_Obj *dictPtr, *keyPtr;
{
    Dict *dict;
    Tcl_HashEntry *hPtr;

    if (Tcl_IsShared(dictPtr)) {
	panic("Tcl_DictObjRemove called with shared object");
    }

    if (dictPtr->typePtr != &tclDictType) {
	int result = SetDictFromAny(interp, dictPtr);
	if (result != TCL_OK) {
	    return result;
	}
    }

    if (dictPtr->bytes != NULL) {
	Tcl_InvalidateStringRep(dictPtr);
    }
    dict = (Dict *) dictPtr->internalRep.otherValuePtr;
    hPtr = Tcl_FindHashEntry(&dict->table, (char *)keyPtr);
    if (hPtr != NULL) {
	Tcl_Obj *valuePtr = (Tcl_Obj *) Tcl_GetHashValue(hPtr);

	Tcl_DecrRefCount(valuePtr);
	Tcl_DeleteHashEntry(hPtr);
	dict->epoch++;
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_DictObjSize --
 *
 *	How many key,value pairs are there in the dictionary?
 *
 * Results:
 *	A standard Tcl result.  Updates the variable pointed to by
 *	sizePtr with the number of key,value pairs in the dictionary.
 *
 * Side effects:
 *	The dictPtr object is converted to a dictionary type if it is
 *	not a dictionary already.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_DictObjSize(interp, dictPtr, sizePtr)
    Tcl_Interp *interp;
    Tcl_Obj *dictPtr;
    int *sizePtr;
{
    Dict *dict;

    if (dictPtr->typePtr != &tclDictType) {
	int result = SetDictFromAny(interp, dictPtr);
	if (result != TCL_OK) {
	    return result;
	}
    }

    dict = (Dict *) dictPtr->internalRep.otherValuePtr;
    *sizePtr = dict->table.numEntries;
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_DictObjFirst --
 *
 *	Start a traversal of the dictionary.  Caller must supply the
 *	search context, pointers for returning key and value, and a
 *	pointer to allow indication of whether the dictionary has been
 *	traversed (i.e. the dictionary is empty.) The order of traversal
 *	is undefined.
 *
 * Results:
 *	A standard Tcl result.  Updates the variables pointed to by
 *	keyPtrPtr, valuePtrPtr and donePtr.  Either of keyPtrPtr and
 *	valuePtrPtr may be NULL, in which case the key/value is not made
 *	available to the caller.
 *
 * Side effects:
 *	The dictPtr object is converted to a dictionary type if it is
 *	not a dictionary already.  The search context is initialised if
 *	the search has not finished.  The dictionary's internal rep is
 *	Tcl_Preserve()d if the dictionary has at least one element.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_DictObjFirst(interp, dictPtr, searchPtr, keyPtrPtr, valuePtrPtr, donePtr)
    Tcl_Interp *interp;			/* For error messages, or NULL if no
					 * error messages desired. */
    Tcl_Obj *dictPtr;			/* Dictionary to traverse. */
    Tcl_DictSearch *searchPtr;		/* Pointer to a dict search context. */
    Tcl_Obj **keyPtrPtr;		/* Pointer to a variable to have the
					 * first key written into, or NULL. */
    Tcl_Obj **valuePtrPtr;		/* Pointer to a variable to have the
					 * first value written into, or NULL.*/
    int *donePtr;			/* Pointer to a variable which will
					 * have a 1 written into when there
					 * are no further values in the
					 * dictionary, or a 0 otherwise. */
{
    Dict *dict;
    Tcl_HashEntry *hPtr;

    if (dictPtr->typePtr != &tclDictType) {
	int result = SetDictFromAny(interp, dictPtr);
	if (result != TCL_OK) {
	    return result;
	}
    }

    dict = (Dict *) dictPtr->internalRep.otherValuePtr;
    hPtr = Tcl_FirstHashEntry(&dict->table, &searchPtr->search);
    if (hPtr == NULL) {
	*donePtr = 1;
    } else {
	*donePtr = 0;
	searchPtr->dictionaryPtr = (Tcl_Dict) dict;
	searchPtr->epoch = dict->epoch;
	dict->refcount++;
	if (keyPtrPtr != NULL) {
	    *keyPtrPtr = (Tcl_Obj *) Tcl_GetHashKey(&dict->table, hPtr);
	}
	if (valuePtrPtr != NULL) {
	    *valuePtrPtr = (Tcl_Obj *) Tcl_GetHashValue(hPtr);
	}
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_DictObjNext --
 *
 *	Continue a traversal of a dictionary previously started with
 *	Tcl_DictObjFirst.  This function is safe against concurrent
 *	modification of the underlying object (including type
 *	shimmering), treating such situations as if the search has
 *	terminated, though it is up to the caller to ensure that the
 *	object itself is not disposed until the search has finished.
 *	It is _not_ safe against modifications from other threads.
 *
 * Results:
 *	Updates the variables pointed to by keyPtrPtr, valuePtrPtr and
 *	donePtr.  Either of keyPtrPtr and valuePtrPtr may be NULL, in
 *	which case the key/value is not made available to the caller.
 *
 * Side effects:
 *	Removes a reference to the dictionary's internal rep if the
 *	search terminates.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_DictObjNext(searchPtr, keyPtrPtr, valuePtrPtr, donePtr)
    Tcl_DictSearch *searchPtr;		/* Pointer to a hash search context. */
    Tcl_Obj **keyPtrPtr;		/* Pointer to a variable to have the
					 * first key written into, or NULL. */
    Tcl_Obj **valuePtrPtr;		/* Pointer to a variable to have the
					 * first value written into, or NULL.*/
    int *donePtr;			/* Pointer to a variable which will
					 * have a 1 written into when there
					 * are no further values in the
					 * dictionary, or a 0 otherwise. */
{
    Tcl_HashEntry *hPtr;

    /*
     * Bail out if the dictionary has had any elements added, modified
     * or removed.  This *shouldn't* happen, but...
     */
    if (((Dict *)searchPtr->dictionaryPtr)->epoch != searchPtr->epoch) {
	panic("concurrent dictionary modification and search");
    }

    hPtr = Tcl_NextHashEntry(&searchPtr->search);
    if (hPtr == NULL) {
	Tcl_DictObjDone(searchPtr);
	*donePtr = 1;
	return;
    }

    *donePtr = 0;
    if (keyPtrPtr != NULL) {
	*keyPtrPtr = (Tcl_Obj *) Tcl_GetHashKey(
		&((Dict *)searchPtr->dictionaryPtr)->table, hPtr);
    }
    if (valuePtrPtr != NULL) {
	*valuePtrPtr = (Tcl_Obj *) Tcl_GetHashValue(hPtr);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_DictObjDone --
 *
 *	Call this if you want to stop a search before you reach the
 *	end of the dictionary (e.g. because of abnormal termination of
 *	the search.)  It should not be used if the search reaches its
 *	natural end (i.e. if either Tcl_DictObjFirst or Tcl_DictObjNext
 *	sets its donePtr variable to 1.)
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Removes a reference to the dictionary's internal rep.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_DictObjDone(searchPtr)
    Tcl_DictSearch *searchPtr;		/* Pointer to a hash search context. */
{
    Dict *dict;

    if (searchPtr->epoch != -1) {
	searchPtr->epoch = -1;
	dict = (Dict *) searchPtr->dictionaryPtr;
	dict->refcount--;
	if (dict->refcount == 0) {
	    DeleteDict(dict);
	}
    }
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_DictObjRemoveKeyList --
 *
 *	Add a key...key,value pair to a dictionary tree.  The main
 *	dictionary value must not be shared, though sub-dictionaries may
 *	be.  All intermediate dictionaries on the path must exist.
 *
 * Results:
 *	A standard Tcl result.  Note that in the error case, a message
 *	is left in interp unless that is NULL.
 *
 * Side effects:
 *	If the dictionary and any of its sub-dictionaries on the
 *	path have string representations, these are invalidated.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_DictObjPutKeyList(interp, dictPtr, keyc, keyv, valuePtr)
    Tcl_Interp *interp;
    int keyc;
    Tcl_Obj *dictPtr, *CONST keyv[], *valuePtr;
{
    Dict *dict;
    Tcl_HashEntry *hPtr;
    int isNew;

    if (Tcl_IsShared(dictPtr)) {
	panic("Tcl_DictObjPutKeyList called with shared object");
    }
    if (keyc < 1) {
	panic("Tcl_DictObjPutKeyList called with empty key list");
    }

    dictPtr = TraceDictPath(interp, dictPtr, keyc-1, keyv, /*willUpdate*/ 1);
    if (dictPtr == NULL) {
	return TCL_ERROR;
    }

    dict = (Dict *) dictPtr->internalRep.otherValuePtr;
    hPtr = Tcl_CreateHashEntry(&dict->table, (char *)keyv[keyc-1], &isNew);
    Tcl_IncrRefCount(valuePtr);
    if (!isNew) {
	Tcl_Obj *oldValuePtr = (Tcl_Obj *) Tcl_GetHashValue(hPtr);
	Tcl_DecrRefCount(oldValuePtr);
    }
    Tcl_SetHashValue(hPtr, valuePtr);
    InvalidateDictChain(dictPtr);

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_DictObjRemoveKeyList --
 *
 *	Remove a key...key,value pair from a dictionary tree (the value
 *	removed is implicit in the key path.)  The main dictionary value
 *	must not be shared, though sub-dictionaries may be.  It is not
 *	an error if there is no value associated with the given key list,
 *	but all intermediate dictionaries on the key path must exist.
 *
 * Results:
 *	A standard Tcl result.  Note that in the error case, a message
 *	is left in interp unless that is NULL.
 *
 * Side effects:
 *	If the dictionary and any of its sub-dictionaries on the key
 *	path have string representations, these are invalidated.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_DictObjRemoveKeyList(interp, dictPtr, keyc, keyv)
    Tcl_Interp *interp;
    int keyc;
    Tcl_Obj *dictPtr, *CONST keyv[];
{
    Dict *dict;
    Tcl_HashEntry *hPtr;

    if (Tcl_IsShared(dictPtr)) {
	panic("Tcl_DictObjRemoveKeyList called with shared object");
    }
    if (keyc < 1) {
	panic("Tcl_DictObjRemoveKeyList called with empty key list");
    }

    dictPtr = TraceDictPath(interp, dictPtr, keyc-1, keyv, /*willUpdate*/ 1);
    if (dictPtr == NULL) {
	return TCL_ERROR;
    }

    dict = (Dict *) dictPtr->internalRep.otherValuePtr;
    hPtr = Tcl_FindHashEntry(&dict->table, (char *)keyv[keyc-1]);
    if (hPtr != NULL) {
	Tcl_DeleteHashEntry(hPtr);
    }
    InvalidateDictChain(dictPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_NewListObj --
 *
 *	This procedure is normally called when not debugging: i.e., when
 *	TCL_MEM_DEBUG is not defined. It creates a new dict object
 *	without any content.
 *
 *	When TCL_MEM_DEBUG is defined, this procedure just returns the
 *	result of calling the debugging version Tcl_DbNewDictObj.
 *
 * Results:
 *	A new dict object is returned; it has no keys defined in it.
 *	The new object's string representation is left NULL, and the
 *	ref count of the object is 0.
 *
 * Side Effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

Tcl_Obj *
Tcl_NewDictObj()
{
#ifdef TCL_MEM_DEBUG
    return Tcl_DbNewDictObj("unknown", 0);
#else /* !TCL_MEM_DEBUG */
    Tcl_Obj *dictPtr;
    Dict *dict;

    TclNewObj(dictPtr);
    Tcl_InvalidateStringRep(dictPtr);
    dict = (Dict *) ckalloc(sizeof(Dict));
    Tcl_InitObjHashTable(&dict->table);
    dict->epoch = 0;
    dict->chain = NULL;
    dictPtr->internalRep.otherValuePtr = (VOID *) dict;
    dictPtr->typePtr = &tclDictType;
    return dictPtr;
#endif
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_DbNewListObj --
 *
 *	This procedure is normally called when debugging: i.e., when
 *	TCL_MEM_DEBUG is defined. It creates new dict objects. It is the
 *	same as the Tcl_NewDictObj procedure above except that it calls
 *	Tcl_DbCkalloc directly with the file name and line number from its
 *	caller. This simplifies debugging since then the [memory active]
 *	command	will report the correct file name and line number when
 *	reporting objects that haven't been freed.
 *
 *	When TCL_MEM_DEBUG is not defined, this procedure just returns the
 *	result of calling Tcl_NewDictObj.
 *
 * Results:
 *	A new dict object is returned; it has no keys defined in it.
 *	The new object's string representation is left NULL, and the
 *	ref count of the object is 0.
 *
 * Side Effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

Tcl_Obj *
Tcl_DbNewDictObj(file, line)
    CONST char *file;
    int line;
{
#ifdef TCL_MEM_DEBUG
    Tcl_Obj *dictPtr;
    Dict *dict;

    TclDbNewObj(dictPtr, file, line);
    Tcl_InvalidateStringRep(dictPtr);
    dict = (Dict *) ckalloc(sizeof(Dict));
    Tcl_InitObjHashTable(&dict->table);
    dict->epoch = 0;
    dict->chain = NULL;
    dictPtr->internalRep.otherValuePtr = (VOID *) dict;
    dictPtr->typePtr = &tclDictType;
    return dictPtr;
#else /* !TCL_MEM_DEBUG */
    return Tcl_NewDictObj();
#endif
}

/***** START OF FUNCTIONS IMPLEMENTING TCL COMMANDS *****/

/*
 *----------------------------------------------------------------------
 *
 * DictCreateCmd --
 *
 *	This function implements the "dict create" Tcl command.
 *	See the user documentation for details on what it does, and
 *	TIP#??? for the formal specification.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
DictCreateCmd(interp, objc, objv)
    Tcl_Interp *interp;
    int objc;
    Tcl_Obj *CONST *objv;
{
    Tcl_Obj *dictObj;
    int i;

    /*
     * Must have an even number of arguments; note that number of
     * preceding arguments (i.e. "dict create" is also even, which
     * makes this much easier.)
     */
    if (objc & 1) {
	Tcl_WrongNumArgs(interp, 2, objv, "?key value ...?");
	return TCL_ERROR;
    }

    dictObj = Tcl_NewDictObj();
    for (i=2 ; i<objc ; i+=2) {
	/*
	 * The next command is assumed to never fail...
	 */
	Tcl_DictObjPut(interp, dictObj, objv[i], objv[i+1]);
    }
    Tcl_SetObjResult(interp, dictObj);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * DictGetCmd --
 *
 *	This function implements the "dict get" Tcl command.
 *	See the user documentation for details on what it does, and
 *	TIP#??? for the formal specification.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
DictGetCmd(interp, objc, objv)
    Tcl_Interp *interp;
    int objc;
    Tcl_Obj *CONST *objv;
{
    Tcl_Obj *dictPtr, *valuePtr = NULL;
    int result;

    if (objc < 3) {
	Tcl_WrongNumArgs(interp, 2, objv, "dictionary ?key key ...?");
	return TCL_ERROR;
    }

    /*
     * Test for the special case of no keys, which returns a *list* of
     * all key,value pairs.  We produce a copy here because that makes
     * subsequent list handling more efficient.
     */

    if (objc == 3) {
	Tcl_Obj *keyPtr, *listPtr;
	Tcl_DictSearch search;
	int done;

	result = Tcl_DictObjFirst(interp, objv[2], &search,
		&keyPtr, &valuePtr, &done);
	if (result != TCL_OK) {
	    return result;
	}
	listPtr = Tcl_NewListObj(0, NULL);
	while (!done) {
	    /*
	     * Assume these won't fail as we have complete control
	     * over the types of things here.
	     */

	    Tcl_ListObjAppendElement(interp, listPtr, keyPtr);
	    Tcl_ListObjAppendElement(interp, listPtr, valuePtr);

	    Tcl_DictObjNext(&search, &keyPtr, &valuePtr, &done);
	}
	Tcl_SetObjResult(interp, listPtr);
	return TCL_OK;
    }

    /*
     * Loop through the list of keys, looking up the key at the
     * current index in the current dictionary each time.  Once we've
     * done the lookup, we set the current dictionary to be the value
     * we looked up (in case the value was not the last one and we are
     * going through a chain of searches.)  Note that this loop always
     * executes at least once.
     */
    dictPtr = TraceDictPath(interp, objv[2], objc-4, objv+3, /*willUpdate*/ 0);
    if (dictPtr == NULL) {
	return TCL_ERROR;
    }
    result = Tcl_DictObjGet(interp, dictPtr, objv[objc-1], &valuePtr);
    if (result != TCL_OK) {
	return result;
    }
    if (valuePtr == NULL) {
	Tcl_ResetResult(interp);
	Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
		"key \"", TclGetString(objv[objc-1]),
		"\" not known in dictionary", NULL);
	return TCL_ERROR;
    }
    Tcl_SetObjResult(interp, valuePtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * DictReplaceCmd --
 *
 *	This function implements the "dict replace" Tcl command.
 *	See the user documentation for details on what it does, and
 *	TIP#??? for the formal specification.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
DictReplaceCmd(interp, objc, objv)
    Tcl_Interp *interp;
    int objc;
    Tcl_Obj *CONST *objv;
{
    Tcl_Obj *dictPtr;
    int i, result;

    if ((objc < 3) || !(objc & 1)) {
	Tcl_WrongNumArgs(interp, 2, objv, "dictionary ?key value ...?");
	return TCL_ERROR;
    }

    dictPtr = objv[2];
    if (Tcl_IsShared(dictPtr)) {
	dictPtr = Tcl_DuplicateObj(dictPtr);
    }
    for (i=3 ; i<objc ; i+=2) {
	result = Tcl_DictObjPut(interp, dictPtr, objv[i], objv[i+1]);
	if (result != TCL_OK) {
	    return TCL_ERROR;
	}
    }
    Tcl_SetObjResult(interp, dictPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * DictRemoveCmd --
 *
 *	This function implements the "dict remove" Tcl command.
 *	See the user documentation for details on what it does, and
 *	TIP#??? for the formal specification.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
DictRemoveCmd(interp, objc, objv)
    Tcl_Interp *interp;
    int objc;
    Tcl_Obj *CONST *objv;
{
    Tcl_Obj *dictPtr;
    int i, result;

    if (objc < 3) {
	Tcl_WrongNumArgs(interp, 2, objv, "dictionary ?key ...?");
	return TCL_ERROR;
    }

    dictPtr = objv[2];
    if (Tcl_IsShared(dictPtr)) {
	dictPtr = Tcl_DuplicateObj(dictPtr);
    }
    for (i=3 ; i<objc ; i++) {
	result = Tcl_DictObjRemove(interp, dictPtr, objv[i]);
	if (result != TCL_OK) {
	    return TCL_ERROR;
	}
    }
    Tcl_SetObjResult(interp, dictPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * DictKeysCmd --
 *
 *	This function implements the "dict keys" Tcl command.
 *	See the user documentation for details on what it does, and
 *	TIP#??? for the formal specification.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
DictKeysCmd(interp, objc, objv)
    Tcl_Interp *interp;
    int objc;
    Tcl_Obj *CONST *objv;
{
    Tcl_Obj *keyPtr, *listPtr;
    Tcl_DictSearch search;
    int result, done;
    char *pattern = NULL;

    if (objc!=3 && objc!=4) {
	Tcl_WrongNumArgs(interp, 2, objv, "dictionary ?pattern?");
	return TCL_ERROR;
    }

    result = Tcl_DictObjFirst(interp, objv[2], &search, &keyPtr, NULL, &done);
    if (result != TCL_OK) {
	return TCL_ERROR;
    }
    if (objc == 4) {
	pattern = TclGetString(objv[3]);
    }
    listPtr = Tcl_NewListObj(0, NULL);
    for (; !done ; Tcl_DictObjNext(&search, &keyPtr, NULL, &done)) {
	if (pattern==NULL || Tcl_StringMatch(TclGetString(keyPtr), pattern)) {
	    /*
	     * Assume this operation always succeeds.
	     */
	    Tcl_ListObjAppendElement(interp, listPtr, keyPtr);
	}
    }
    Tcl_SetObjResult(interp, listPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * DictValuesCmd --
 *
 *	This function implements the "dict values" Tcl command.
 *	See the user documentation for details on what it does, and
 *	TIP#??? for the formal specification.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
DictValuesCmd(interp, objc, objv)
    Tcl_Interp *interp;
    int objc;
    Tcl_Obj *CONST *objv;
{
    Tcl_Obj *valuePtr, *listPtr;
    Tcl_DictSearch search;
    int result, done;
    char *pattern = NULL;

    if (objc!=3 && objc!=4) {
	Tcl_WrongNumArgs(interp, 2, objv, "dictionary ?pattern?");
	return TCL_ERROR;
    }

    result= Tcl_DictObjFirst(interp, objv[2], &search, NULL, &valuePtr, &done);
    if (result != TCL_OK) {
	return TCL_ERROR;
    }
    if (objc == 4) {
	pattern = TclGetString(objv[3]);
    }
    listPtr = Tcl_NewListObj(0, NULL);
    for (; !done ; Tcl_DictObjNext(&search, NULL, &valuePtr, &done)) {
	if (pattern==NULL || Tcl_StringMatch(TclGetString(valuePtr),pattern)) {
	    /*
	     * Assume this operation always succeeds.
	     */
	    Tcl_ListObjAppendElement(interp, listPtr, valuePtr);
	}
    }
    Tcl_SetObjResult(interp, listPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * DictSizeCmd --
 *
 *	This function implements the "dict size" Tcl command.
 *	See the user documentation for details on what it does, and
 *	TIP#??? for the formal specification.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
DictSizeCmd(interp, objc, objv)
    Tcl_Interp *interp;
    int objc;
    Tcl_Obj *CONST *objv;
{
    int result, size;

    if (objc != 3) {
	Tcl_WrongNumArgs(interp, 2, objv, "dictionary");
	return TCL_ERROR;
    }
    result = Tcl_DictObjSize(interp, objv[2], &size);
    if (result == TCL_OK) {
	Tcl_SetObjResult(interp, Tcl_NewIntObj(size));
    }
    return result;
}

/*
 *----------------------------------------------------------------------
 *
 * DictExistsCmd --
 *
 *	This function implements the "dict exists" Tcl command.
 *	See the user documentation for details on what it does, and
 *	TIP#??? for the formal specification.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
DictExistsCmd(interp, objc, objv)
    Tcl_Interp *interp;
    int objc;
    Tcl_Obj *CONST *objv;
{
    Tcl_Obj *dictPtr, *valuePtr;
    int result;

    if (objc < 4) {
	Tcl_WrongNumArgs(interp, 2, objv, "dictionary key ?key ...?");
	return TCL_ERROR;
    }

    dictPtr = TraceDictPath(interp, objv[2], objc-4, objv+3, /*willUpdate*/ 0);
    if (dictPtr == NULL) {
	return TCL_ERROR;
    }
    result = Tcl_DictObjGet(interp, dictPtr, objv[objc-1], &valuePtr);
    if (result != TCL_OK) {
	return result;
    }
    Tcl_SetObjResult(interp, Tcl_NewBooleanObj(valuePtr != NULL));
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * DictInfoCmd --
 *
 *	This function implements the "dict info" Tcl command.
 *	See the user documentation for details on what it does, and
 *	TIP#??? for the formal specification.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
DictInfoCmd(interp, objc, objv)
    Tcl_Interp *interp;
    int objc;
    Tcl_Obj *CONST *objv;
{
    Tcl_Obj *dictPtr;
    Dict *dict;

    if (objc != 3) {
	Tcl_WrongNumArgs(interp, 2, objv, "dictionary");
	return TCL_ERROR;
    }

    dictPtr = objv[2];
    if (dictPtr->typePtr != &tclDictType) {
	int result = SetDictFromAny(interp, dictPtr);
	if (result != TCL_OK) {
	    return result;
	}
    }
    dict = (Dict *)dictPtr->internalRep.otherValuePtr;
    Tcl_SetObjResult(interp,
	    Tcl_NewStringObj(Tcl_HashStats(&dict->table), -1));
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * DictIncrCmd --
 *
 *	This function implements the "dict incr" Tcl command.
 *	See the user documentation for details on what it does, and
 *	TIP#??? for the formal specification.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
DictIncrCmd(interp, objc, objv)
    Tcl_Interp *interp;
    int objc;
    Tcl_Obj *CONST *objv;
{
    Tcl_Obj *dictPtr, *valuePtr, *resultPtr;
    int result, incrValue;

    if (objc < 4 || objc > 5) {
	Tcl_WrongNumArgs(interp, 2, objv, "varName key ?increment?");
	return TCL_ERROR;
    }

    if (objc == 5) {
	result = Tcl_GetIntFromObj(interp, objv[4], &incrValue);
	if (result != TCL_OK) {
	    return result;
	}
    } else {
	incrValue = 1;
    }

    dictPtr = Tcl_ObjGetVar2(interp, objv[2], NULL, 0);
    if (dictPtr == NULL) {
	dictPtr = Tcl_NewDictObj();
	Tcl_DictObjPut(interp, dictPtr, objv[3], Tcl_NewIntObj(incrValue));
    } else {
	int iValue;
	Tcl_WideInt wValue;

	if (Tcl_IsShared(dictPtr)) {
	    dictPtr = Tcl_DuplicateObj(dictPtr);
	}

	if (Tcl_DictObjGet(interp, dictPtr, objv[3], &valuePtr) != TCL_OK) {
	    return TCL_ERROR;
	}
	if (valuePtr == NULL) {
	    valuePtr = Tcl_NewIntObj(incrValue);
	} else if (valuePtr->typePtr == &tclWideIntType) {
	    Tcl_GetWideIntFromObj(NULL, valuePtr, &wValue);
	    if (Tcl_IsShared(valuePtr)) {
		valuePtr = Tcl_NewWideIntObj(wValue + incrValue);
	    } else {
		Tcl_SetWideIntObj(valuePtr, wValue + incrValue);
		if (dictPtr->bytes != NULL) {
		    Tcl_InvalidateStringRep(dictPtr);
		}
		goto valueAlreadyInDictionary;
	    }
	} else if (valuePtr->typePtr == &tclIntType) {
	    Tcl_GetIntFromObj(NULL, valuePtr, &iValue);
	    if (Tcl_IsShared(valuePtr)) {
		valuePtr = Tcl_NewIntObj(iValue + incrValue);
	    } else {
		Tcl_SetIntObj(valuePtr, iValue + incrValue);
		if (dictPtr->bytes != NULL) {
		    Tcl_InvalidateStringRep(dictPtr);
		}
		goto valueAlreadyInDictionary;
	    }
	} else {
	    result = Tcl_GetWideIntFromObj(interp, valuePtr, &wValue);
	    if (result != TCL_OK) {
		return result;
	    }
	    /*
	     * Determine if we should have got a standard int instead.
	     */
	    if (Tcl_IsShared(valuePtr)) {
		if (wValue >= INT_MIN && wValue <= INT_MAX) {
		    /*
		     * Convert the type...
		     */
		    Tcl_GetIntFromObj(NULL, valuePtr, &iValue);
		    valuePtr = Tcl_NewIntObj(iValue + incrValue);
		} else {
		    valuePtr = Tcl_NewWideIntObj(wValue + incrValue);
		}
	    } else {
		if (wValue >= INT_MIN && wValue <= INT_MAX) {
		    Tcl_SetIntObj(valuePtr,
			    Tcl_WideAsLong(wValue) + incrValue);
		} else {
		    Tcl_SetWideIntObj(valuePtr, wValue + incrValue);
		}
		if (dictPtr->bytes != NULL) {
		    Tcl_InvalidateStringRep(dictPtr);
		}
		goto valueAlreadyInDictionary;
	    }
	}
	if (Tcl_DictObjPut(interp, dictPtr, objv[3], valuePtr) != TCL_OK) {
	    Tcl_DecrRefCount(valuePtr);
	    return TCL_ERROR;
	}
	valueAlreadyInDictionary:
    }
    resultPtr = Tcl_ObjSetVar2(interp, objv[2], NULL, dictPtr,
	    TCL_LEAVE_ERR_MSG);
    if (resultPtr == NULL) {
	Tcl_DecrRefCount(dictPtr);
	return TCL_ERROR;
    }
    Tcl_SetObjResult(interp, resultPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * DictLappendCmd --
 *
 *	This function implements the "dict lappend" Tcl command.
 *	See the user documentation for details on what it does, and
 *	TIP#??? for the formal specification.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
DictLappendCmd(interp, objc, objv)
    Tcl_Interp *interp;
    int objc;
    Tcl_Obj *CONST *objv;
{
    Tcl_Obj *dictPtr, *valuePtr, *resultPtr;
    int i, allocatedDict = 0, allocatedValue = 0;

    if (objc < 4) {
	Tcl_WrongNumArgs(interp, 2, objv, "varName key ?value ...?");
	return TCL_ERROR;
    }

    dictPtr = Tcl_ObjGetVar2(interp, objv[2], NULL, 0);
    if (dictPtr == NULL) {
	allocatedDict = 1;
	dictPtr = Tcl_NewDictObj();
    } else if (Tcl_IsShared(dictPtr)) {
	allocatedDict = 1;
	dictPtr = Tcl_DuplicateObj(dictPtr);
    }

    if (Tcl_DictObjGet(interp, dictPtr, objv[3], &valuePtr) != TCL_OK) {
	if (allocatedDict) {
	    Tcl_DecrRefCount(dictPtr);
	}
	return TCL_ERROR;
    }

    if (valuePtr == NULL) {
	valuePtr = Tcl_NewListObj(objc-4, objv+4);
	allocatedValue = 1;
    } else {
	if (Tcl_IsShared(valuePtr)) {
	    allocatedValue = 1;
	    valuePtr = Tcl_DuplicateObj(valuePtr);
	}

	for (i=4 ; i<objc ; i++) {
	    if (Tcl_ListObjAppendElement(interp, valuePtr,
		    objv[i]) != TCL_OK) {
		if (allocatedValue) {
		    Tcl_DecrRefCount(valuePtr);
		}
		if (allocatedDict) {
		    Tcl_DecrRefCount(dictPtr);
		}
		return TCL_ERROR;
	    }
	}
    }

    if (allocatedValue) {
	Tcl_DictObjPut(interp, dictPtr, objv[3], valuePtr);
    } else if (dictPtr->bytes != NULL) {
	Tcl_InvalidateStringRep(dictPtr);
    }

    resultPtr = Tcl_ObjSetVar2(interp, objv[2], NULL, dictPtr,
	    TCL_LEAVE_ERR_MSG);
    if (resultPtr == NULL) {
	if (allocatedDict) {
	    Tcl_DecrRefCount(dictPtr);
	}
	return TCL_ERROR;
    }
    Tcl_SetObjResult(interp, resultPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * DictAppendCmd --
 *
 *	This function implements the "dict append" Tcl command.
 *	See the user documentation for details on what it does, and
 *	TIP#??? for the formal specification.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
DictAppendCmd(interp, objc, objv)
    Tcl_Interp *interp;
    int objc;
    Tcl_Obj *CONST *objv;
{
    Tcl_Obj *dictPtr, *valuePtr, *resultPtr;
    int i, allocatedDict = 0;

    if (objc < 4) {
	Tcl_WrongNumArgs(interp, 2, objv, "varName key ?value ...?");
	return TCL_ERROR;
    }

    dictPtr = Tcl_ObjGetVar2(interp, objv[2], NULL, 0);
    if (dictPtr == NULL) {
	allocatedDict = 1;
	dictPtr = Tcl_NewDictObj();
    } else if (Tcl_IsShared(dictPtr)) {
	allocatedDict = 1;
	dictPtr = Tcl_DuplicateObj(dictPtr);
    }

    if (Tcl_DictObjGet(interp, dictPtr, objv[3], &valuePtr) != TCL_OK) {
	if (allocatedDict) {
	    Tcl_DecrRefCount(dictPtr);
	}
	return TCL_ERROR;
    }

    if (valuePtr == NULL) {
	TclNewObj(valuePtr);
    } else {
	if (Tcl_IsShared(valuePtr)) {
	    valuePtr = Tcl_DuplicateObj(valuePtr);
	}
    }

    for (i=4 ; i<objc ; i++) {
	Tcl_AppendObjToObj(valuePtr, objv[i]);
    }

    Tcl_DictObjPut(interp, dictPtr, objv[3], valuePtr);

    resultPtr = Tcl_ObjSetVar2(interp, objv[2], NULL, dictPtr,
	    TCL_LEAVE_ERR_MSG);
    if (resultPtr == NULL) {
	if (allocatedDict) {
	    Tcl_DecrRefCount(dictPtr);
	}
	return TCL_ERROR;
    }
    Tcl_SetObjResult(interp, resultPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * DictForCmd --
 *
 *	This function implements the "dict for" Tcl command.
 *	See the user documentation for details on what it does, and
 *	TIP#??? for the formal specification.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
DictForCmd(interp, objc, objv)
    Tcl_Interp *interp;
    int objc;
    Tcl_Obj *CONST *objv;
{
    Tcl_Obj *dictObj, *scriptObj, *keyVarObj, *valueVarObj;
    Tcl_Obj **varv, *keyObj, *valueObj;
    Tcl_DictSearch search;
    int varc, done, result;

    if (objc != 5) {
	Tcl_WrongNumArgs(interp, 2, objv,
		"{keyVar valueVar} dictionary script");
	return TCL_ERROR;
    }

    if (Tcl_ListObjGetElements(interp, objv[2], &varc, &varv) != TCL_OK) {
	return TCL_ERROR;
    }
    if (varc != 2) {
	Tcl_ResetResult(interp);
	Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
		"must have exactly two variable names", NULL);
	return TCL_ERROR;
    }
    keyVarObj = varv[0];
    valueVarObj = varv[1];
    dictObj = objv[3];
    scriptObj = objv[4];
    /*
     * Make sure that these objects (which we need throughout the body
     * of the loop) don't vanish.  Note that we also care that the
     * dictObj remains a dictionary, which requires slightly more
     * elaborate precautions.  That we achieve by making sure that the
     * type is static throughout and that the hash is the same hash
     * throughout; taking a copy of the whole thing would be easier,
     * but much less efficient.
     */
    Tcl_IncrRefCount(keyVarObj);
    Tcl_IncrRefCount(valueVarObj);
    Tcl_IncrRefCount(dictObj);
    Tcl_IncrRefCount(scriptObj);

    result = Tcl_DictObjFirst(interp, dictObj,
	    &search, &keyObj, &valueObj, &done);
    if (result != TCL_OK) {
	Tcl_DecrRefCount(keyVarObj);
	Tcl_DecrRefCount(valueVarObj);
	Tcl_DecrRefCount(dictObj);
	Tcl_DecrRefCount(scriptObj);
	return TCL_ERROR;
    }

    while (!done) {
	/*
	 * Stop the value from getting hit in any way by any traces on
	 * the key variable.
	 */
	Tcl_IncrRefCount(valueObj);
	if (Tcl_ObjSetVar2(interp, keyVarObj, NULL, keyObj,
		TCL_LEAVE_ERR_MSG) == NULL) {
	    Tcl_ResetResult(interp);
	    Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
		    "couldn't set key variable: \"",
		    Tcl_GetString(keyVarObj), "\"", (char *) NULL);
	    Tcl_DecrRefCount(valueObj);
	errorExit:
	    Tcl_DictObjDone(&search);
	    Tcl_DecrRefCount(keyVarObj);
	    Tcl_DecrRefCount(valueVarObj);
	    Tcl_DecrRefCount(dictObj);
	    Tcl_DecrRefCount(scriptObj);
	    return TCL_ERROR;
	}
	Tcl_DecrRefCount(valueObj);
	if (Tcl_ObjSetVar2(interp, valueVarObj, NULL, valueObj,
		TCL_LEAVE_ERR_MSG) == NULL) {
	    Tcl_ResetResult(interp);
	    Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
		    "couldn't set value variable: \"",
		    Tcl_GetString(keyVarObj), "\"", (char *) NULL);
	    goto errorExit;
	}

	result = Tcl_EvalObjEx(interp, scriptObj, 0);
	if (result != TCL_OK) {
	    if (result == TCL_CONTINUE) {
		result = TCL_OK;
	    } else if (result == TCL_BREAK) {
		result = TCL_OK;
		Tcl_DictObjDone(&search);
		break;
	    } else if (result == TCL_ERROR) {
                char msg[32 + TCL_INTEGER_SPACE];

		sprintf(msg, "\n    (\"dict for\" body line %d)",
			interp->errorLine);
		Tcl_AddObjErrorInfo(interp, msg, -1);
		Tcl_DictObjDone(&search);
		break;
	    } else {
		Tcl_DictObjDone(&search);
		break;
	    }
	}

	Tcl_DictObjNext(&search, &keyObj, &valueObj, &done);
    }

    /*
     * Stop holding a reference to these objects.
     */
    Tcl_DecrRefCount(keyVarObj);
    Tcl_DecrRefCount(valueVarObj);
    Tcl_DecrRefCount(dictObj);
    Tcl_DecrRefCount(scriptObj);

    if (result == TCL_OK) {
	Tcl_ResetResult(interp);
    }
    return result;
}

/*
 *----------------------------------------------------------------------
 *
 * DictSetCmd --
 *
 *	This function implements the "dict set" Tcl command.
 *	See the user documentation for details on what it does, and
 *	TIP#??? for the formal specification.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
DictSetCmd(interp, objc, objv)
    Tcl_Interp *interp;
    int objc;
    Tcl_Obj *CONST *objv;
{
    Tcl_Obj *dictPtr, *resultPtr;
    int result, allocatedDict = 0;

    if (objc < 5) {
	Tcl_WrongNumArgs(interp, 2, objv, "varName key ?key ...? value");
	return TCL_ERROR;
    }

    dictPtr = Tcl_ObjGetVar2(interp, objv[2], NULL, 0);
    if (dictPtr == NULL) {
	allocatedDict = 1;
	dictPtr = Tcl_NewDictObj();
    } else if (Tcl_IsShared(dictPtr)) {
	allocatedDict = 1;
	dictPtr = Tcl_DuplicateObj(dictPtr);
    }

    result = Tcl_DictObjPutKeyList(interp, dictPtr, objc-4, objv+3,
	    objv[objc-1]);
    if (result != TCL_OK) {
	if (allocatedDict) {
	    Tcl_DecrRefCount(dictPtr);
	}
	return TCL_ERROR;
    }

    resultPtr = Tcl_ObjSetVar2(interp, objv[2], NULL, dictPtr,
	    TCL_LEAVE_ERR_MSG);
    if (resultPtr == NULL) {
	if (allocatedDict) {
	    Tcl_DecrRefCount(dictPtr);
	}
	return TCL_ERROR;
    }
    Tcl_SetObjResult(interp, resultPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * DictUnsetCmd --
 *
 *	This function implements the "dict unset" Tcl command.
 *	See the user documentation for details on what it does, and
 *	TIP#??? for the formal specification.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
DictUnsetCmd(interp, objc, objv)
    Tcl_Interp *interp;
    int objc;
    Tcl_Obj *CONST *objv;
{
    Tcl_Obj *dictPtr, *resultPtr;
    int result, allocatedDict = 0;

    if (objc < 4) {
	Tcl_WrongNumArgs(interp, 2, objv, "varName key ?key ...?");
	return TCL_ERROR;
    }

    dictPtr = Tcl_ObjGetVar2(interp, objv[2], NULL, 0);
    if (dictPtr == NULL) {
	allocatedDict = 1;
	dictPtr = Tcl_NewDictObj();
    } else if (Tcl_IsShared(dictPtr)) {
	allocatedDict = 1;
	dictPtr = Tcl_DuplicateObj(dictPtr);
    }

    result = Tcl_DictObjRemoveKeyList(interp, dictPtr, objc-3, objv+3);
    if (result != TCL_OK) {
	if (allocatedDict) {
	    Tcl_DecrRefCount(dictPtr);
	}
	return TCL_ERROR;
    }

    resultPtr = Tcl_ObjSetVar2(interp, objv[2], NULL, dictPtr,
	    TCL_LEAVE_ERR_MSG);
    if (resultPtr == NULL) {
	if (allocatedDict) {
	    Tcl_DecrRefCount(dictPtr);
	}
	return TCL_ERROR;
    }
    Tcl_SetObjResult(interp, resultPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * DictFilterCmd --
 *
 *	This function implements the "dict filter" Tcl command.
 *	See the user documentation for details on what it does, and
 *	TIP#??? for the formal specification.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
DictFilterCmd(interp, objc, objv)
    Tcl_Interp *interp;
    int objc;
    Tcl_Obj *CONST *objv;
{
    static CONST char *filters[] = {
	"key", "script", "value", NULL
    };
    enum FilterTypes {
	FILTER_KEYS, FILTER_SCRIPT, FILTER_VALUES
    };
    Tcl_Obj *dictObj, *scriptObj, *keyVarObj, *valueVarObj;
    Tcl_Obj **varv, *keyObj, *valueObj, *resultObj, *boolObj;
    Tcl_DictSearch search;
    int index, varc, done, result, satisfied;
    char *pattern;
    char msg[32 + TCL_INTEGER_SPACE];

    if (objc < 4) {
	Tcl_WrongNumArgs(interp, 2, objv, "dictionary filterType ...");
	return TCL_ERROR;
    }
    if (Tcl_GetIndexFromObj(interp, objv[3], filters, "filterType",
	     0, &index) != TCL_OK) {
	return TCL_ERROR;
    }

    switch ((enum FilterTypes) index) {
    case FILTER_KEYS:
	if (objc != 5) {
	    Tcl_WrongNumArgs(interp, 2, objv, "dictionary key globPattern");
	    return TCL_ERROR;
	}

	/*
	 * Create a dictionary whose keys all match a certain pattern.
	 */
	if (Tcl_DictObjFirst(interp, objv[2], &search,
		&keyObj, &valueObj, &done) != TCL_OK) {
	    return TCL_ERROR;
	}
	pattern = TclGetString(objv[4]);
	resultObj = Tcl_NewDictObj();
	while (!done) {
	    if (Tcl_StringMatch(TclGetString(keyObj), pattern)) {
		Tcl_DictObjPut(interp, resultObj, keyObj, valueObj);
	    }
	    Tcl_DictObjNext(&search, &keyObj, &valueObj, &done);
	}
	Tcl_SetObjResult(interp, resultObj);
	return TCL_OK;

    case FILTER_VALUES:
	if (objc != 5) {
	    Tcl_WrongNumArgs(interp, 2, objv, "dictionary value globPattern");
	    return TCL_ERROR;
	}

	/*
	 * Create a dictionary whose values all match a certain pattern.
	 */
	if (Tcl_DictObjFirst(interp, objv[2], &search,
		&keyObj, &valueObj, &done) != TCL_OK) {
	    return TCL_ERROR;
	}
	pattern = TclGetString(objv[4]);
	resultObj = Tcl_NewDictObj();
	while (!done) {
	    if (Tcl_StringMatch(TclGetString(valueObj), pattern)) {
		Tcl_DictObjPut(interp, resultObj, keyObj, valueObj);
	    }
	    Tcl_DictObjNext(&search, &keyObj, &valueObj, &done);
	}
	Tcl_SetObjResult(interp, resultObj);
	return TCL_OK;

    case FILTER_SCRIPT:
	if (objc != 6) {
	    Tcl_WrongNumArgs(interp, 2, objv,
		    "dictionary script {keyVar valueVar} filterScript");
	    return TCL_ERROR;
	}

	/*
	 * Create a dictionary whose key,value pairs all satisfy a
	 * script (i.e. get a true boolean result from its
	 * evaluation.)  Massive copying from the "dict for"
	 * implementation has occurred!
	 */

	if (Tcl_ListObjGetElements(interp, objv[4], &varc, &varv) != TCL_OK) {
	    return TCL_ERROR;
	}
	if (varc != 2) {
	    Tcl_ResetResult(interp);
	    Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
		    "must have exactly two variable names", NULL);
	    return TCL_ERROR;
	}
	keyVarObj = varv[0];
	valueVarObj = varv[1];
	dictObj = objv[2];
	scriptObj = objv[5];
	/*
	 * Make sure that these objects (which we need throughout the
	 * body of the loop) don't vanish.  Note that we also care
	 * that the dictObj remains a dictionary, which requires
	 * slightly more elaborate precautions.  That we achieve by
	 * making sure that the type is static throughout and that the
	 * hash is the same hash throughout; taking a copy of the
	 * whole thing would be easier, but much less efficient.
	 */
	Tcl_IncrRefCount(keyVarObj);
	Tcl_IncrRefCount(valueVarObj);
	Tcl_IncrRefCount(dictObj);
	Tcl_IncrRefCount(scriptObj);

	result = Tcl_DictObjFirst(interp, dictObj,
		&search, &keyObj, &valueObj, &done);
	if (result != TCL_OK) {
	    Tcl_DecrRefCount(keyVarObj);
	    Tcl_DecrRefCount(valueVarObj);
	    Tcl_DecrRefCount(dictObj);
	    Tcl_DecrRefCount(scriptObj);
	    return TCL_ERROR;
	}

	resultObj = Tcl_NewDictObj();

	while (!done) {
	    /*
	     * Stop the value from getting hit in any way by any
	     * traces on the key variable.
	     */
	    Tcl_IncrRefCount(keyObj);
	    Tcl_IncrRefCount(valueObj);
	    if (Tcl_ObjSetVar2(interp, keyVarObj, NULL, keyObj,
		    TCL_LEAVE_ERR_MSG) == NULL) {
		Tcl_ResetResult(interp);
		Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
			"couldn't set key variable: \"",
			Tcl_GetString(keyVarObj), "\"", (char *) NULL);
		result = TCL_ERROR;
		goto abnormalResult;
	    }
	    if (Tcl_ObjSetVar2(interp, valueVarObj, NULL, valueObj,
		    TCL_LEAVE_ERR_MSG) == NULL) {
		Tcl_ResetResult(interp);
		Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
			"couldn't set value variable: \"",
			Tcl_GetString(keyVarObj), "\"", (char *) NULL);
		goto abnormalResult;
	    }

	    result = Tcl_EvalObjEx(interp, scriptObj, 0);
	    switch (result) {
	    case TCL_OK:
		boolObj = Tcl_GetObjResult(interp);
		Tcl_IncrRefCount(boolObj);
		Tcl_ResetResult(interp);
		if (Tcl_GetBooleanFromObj(interp, boolObj,
			&satisfied) != TCL_OK) {
		    Tcl_DecrRefCount(boolObj);
		    result = TCL_ERROR;
		    goto abnormalResult;
		}
		Tcl_DecrRefCount(boolObj);
		if (satisfied) {
		    Tcl_DictObjPut(interp, resultObj, keyObj, valueObj);
		}
	    case TCL_CONTINUE:
		result = TCL_OK;
		break;
	    case TCL_BREAK:
		/*
		 * Force loop termination.  Has to be done with a jump
		 * so we remove references to the dictionary correctly.
		 */
		Tcl_ResetResult(interp);
		Tcl_DictObjDone(&search);
		result = TCL_OK;
		goto normalResult;
	    case TCL_ERROR:
		sprintf(msg, "\n    (\"dict filter\" script line %d)",
			interp->errorLine);
		Tcl_AddObjErrorInfo(interp, msg, -1);
	    default:
		goto abnormalResult;
	    }

	    Tcl_DecrRefCount(keyObj);
	    Tcl_DecrRefCount(valueObj);

	    Tcl_DictObjNext(&search, &keyObj, &valueObj, &done);
	}

    normalResult:
	/*
	 * Stop holding a reference to these objects.
	 */
	Tcl_DecrRefCount(keyVarObj);
	Tcl_DecrRefCount(valueVarObj);
	Tcl_DecrRefCount(dictObj);
	Tcl_DecrRefCount(scriptObj);

	if (result == TCL_OK) {
	    Tcl_SetObjResult(interp, resultObj);
	} else {
	    Tcl_DecrRefCount(resultObj);
	}
	return result;
    }
    panic("unexpected fallthrough");
    /* Control never reaches this point. */

  abnormalResult:
    Tcl_DictObjDone(&search);
    Tcl_DecrRefCount(keyObj);
    Tcl_DecrRefCount(valueObj);
    Tcl_DecrRefCount(keyVarObj);
    Tcl_DecrRefCount(valueVarObj);
    Tcl_DecrRefCount(dictObj);
    Tcl_DecrRefCount(scriptObj);
    Tcl_DecrRefCount(resultObj);
    return result;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_DictObjCmd --
 *
 *	This function is invoked to process the "dict" Tcl command.
 *	See the user documentation for details on what it does, and
 *	TIP#??? for the formal specification.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_DictObjCmd(/*ignored*/ clientData, interp, objc, objv)
    ClientData clientData;
    Tcl_Interp *interp;
    int objc;
    Tcl_Obj *CONST *objv;
{
    static CONST char *subcommands[] = {
	"append", "create", "exists", "filter", "for",
	"get", "incr", "info", "keys", "lappend", "remove",
	"replace", "set", "size", "unset", "values", NULL
    };
    enum DictSubcommands {
	DICT_APPEND, DICT_CREATE, DICT_EXISTS, DICT_FILTER, DICT_FOR,
	DICT_GET, DICT_INCR, DICT_INFO, DICT_KEYS, DICT_LAPPEND, DICT_REMOVE,
	DICT_REPLACE, DICT_SET, DICT_SIZE, DICT_UNSET, DICT_VALUES
    };
    int index;

    if (objc < 2) {
	Tcl_WrongNumArgs(interp, 1, objv, "subcommand ?arg ...?");
	return TCL_ERROR;
    }
    if (Tcl_GetIndexFromObj(interp, objv[1], subcommands, "subcommand",
	    0, &index) != TCL_OK) {
	return TCL_ERROR;
    }
    switch ((enum DictSubcommands) index) {
    case DICT_APPEND:	return DictAppendCmd(interp, objc, objv);
    case DICT_CREATE:	return DictCreateCmd(interp, objc, objv);
    case DICT_EXISTS:	return DictExistsCmd(interp, objc, objv);
    case DICT_FILTER:	return DictFilterCmd(interp, objc, objv);
    case DICT_FOR:	return DictForCmd(interp, objc, objv);
    case DICT_GET:	return DictGetCmd(interp, objc, objv);
    case DICT_INCR:	return DictIncrCmd(interp, objc, objv);
    case DICT_INFO:	return DictInfoCmd(interp, objc, objv);
    case DICT_KEYS:	return DictKeysCmd(interp, objc, objv);
    case DICT_LAPPEND:	return DictLappendCmd(interp, objc, objv);
    case DICT_REMOVE:	return DictRemoveCmd(interp, objc, objv);
    case DICT_REPLACE:	return DictReplaceCmd(interp, objc, objv);
    case DICT_SET:	return DictSetCmd(interp, objc, objv);
    case DICT_SIZE:	return DictSizeCmd(interp, objc, objv);
    case DICT_UNSET:	return DictUnsetCmd(interp, objc, objv);
    case DICT_VALUES:	return DictValuesCmd(interp, objc, objv);
    }
    panic("unexpected fallthrough!");
}