Hive off the ensemble code into its own file.

Split the [switch] compiler for sanity's sake.

1 files changed, 2965 insertions, 0 deletions

diff --git a/generic/tclEnsemble.c b/generic/tclEnsemble.c
new file mode 100644
index 0000000..4dd86b7
--- /dev/null
+++ b/generic/tclEnsemble.c
@@ -0,0 +1,2965 @@
+/*
+ * tclEnsemble.c --
+ *
+ *	Contains support for ensembles, which provide simple mechanism
+ *	for creating composite commands on top of namespaces.
+ *
+ * Copyright (c) 2005-2010 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: tclEnsemble.c,v 1.1 2010/02/13 18:11:06 dkf Exp $
+ */
+
+#include "tclInt.h"
+#include "tclCompile.h"
+
+/*
+ * Declarations for functions local to this file:
+ */
+
+static inline int	EnsembleUnknownCallback(Tcl_Interp *interp,
+			    EnsembleConfig *ensemblePtr, int objc,
+			    Tcl_Obj *const objv[], Tcl_Obj **prefixObjPtr);
+static int		NsEnsembleImplementationCmd(ClientData clientData,
+			    Tcl_Interp *interp,int objc,Tcl_Obj *const objv[]);
+static int		NsEnsembleImplementationCmdNR(ClientData clientData,
+			    Tcl_Interp *interp,int objc,Tcl_Obj *const objv[]);
+static void		BuildEnsembleConfig(EnsembleConfig *ensemblePtr);
+static int		NsEnsembleStringOrder(const void *strPtr1,
+			    const void *strPtr2);
+static void		DeleteEnsembleConfig(ClientData clientData);
+static void		MakeCachedEnsembleCommand(Tcl_Obj *objPtr,
+			    EnsembleConfig *ensemblePtr,
+			    const char *subcmdName, Tcl_Obj *prefixObjPtr);
+static void		FreeEnsembleCmdRep(Tcl_Obj *objPtr);
+static void		DupEnsembleCmdRep(Tcl_Obj *objPtr, Tcl_Obj *copyPtr);
+static void		StringOfEnsembleCmdRep(Tcl_Obj *objPtr);
+
+/*
+ * This structure defines a Tcl object type that contains a reference to an
+ * ensemble subcommand (e.g. the "length" in [string length ab]). It is used
+ * to cache the mapping between the subcommand itself and the real command
+ * that implements it.
+ */
+
+const Tcl_ObjType tclEnsembleCmdType = {
+    "ensembleCommand",		/* the type's name */
+    FreeEnsembleCmdRep,		/* freeIntRepProc */
+    DupEnsembleCmdRep,		/* dupIntRepProc */
+    StringOfEnsembleCmdRep,	/* updateStringProc */
+    NULL			/* setFromAnyProc */
+};
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclNamespaceEnsembleCmd --
+ *
+ *	Invoked to implement the "namespace ensemble" command that creates and
+ *	manipulates ensembles built on top of namespaces. Handles the
+ *	following syntax:
+ *
+ *	    namespace ensemble name ?dictionary?
+ *
+ * Results:
+ *	Returns TCL_OK if successful, and TCL_ERROR if anything goes wrong.
+ *
+ * Side effects:
+ *	Creates the ensemble for the namespace if one did not previously
+ *	exist. Alternatively, alters the way that the ensemble's subcommand =>
+ *	implementation prefix is configured.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+TclNamespaceEnsembleCmd(
+    ClientData dummy,
+    Tcl_Interp *interp,
+    int objc,
+    Tcl_Obj *const objv[])
+{
+    Namespace *nsPtr;
+    Tcl_Command token;
+    static const char *const subcommands[] = {
+	"configure", "create", "exists", NULL
+    };
+    enum EnsSubcmds {
+	ENS_CONFIG, ENS_CREATE, ENS_EXISTS
+    };
+    static const char *const createOptions[] = {
+	"-command", "-map", "-parameters", "-prefixes", "-subcommands",
+	"-unknown", NULL
+    };
+    enum EnsCreateOpts {
+	CRT_CMD, CRT_MAP, CRT_PARAM, CRT_PREFIX, CRT_SUBCMDS, CRT_UNKNOWN
+    };
+    static const char *const configOptions[] = {
+	"-map", "-namespace", "-parameters", "-prefixes", "-subcommands",
+	"-unknown", NULL
+    };
+    enum EnsConfigOpts {
+	CONF_MAP, CONF_NAMESPACE, CONF_PARAM, CONF_PREFIX, CONF_SUBCMDS,
+	CONF_UNKNOWN
+    };
+    int index;
+
+    nsPtr = (Namespace *) TclGetCurrentNamespace(interp);
+    if (nsPtr == NULL || nsPtr->flags & NS_DYING) {
+	if (!Tcl_InterpDeleted(interp)) {
+	    Tcl_AppendResult(interp,
+		    "tried to manipulate ensemble of deleted namespace", NULL);
+	}
+	return TCL_ERROR;
+    }
+
+    if (objc < 3) {
+	Tcl_WrongNumArgs(interp, 2, objv, "subcommand ?arg ...?");
+	return TCL_ERROR;
+    }
+    if (Tcl_GetIndexFromObj(interp, objv[2], subcommands, "subcommand", 0,
+	    &index) != TCL_OK) {
+	return TCL_ERROR;
+    }
+
+    switch ((enum EnsSubcmds) index) {
+    case ENS_CREATE: {
+	const char *name;
+	Tcl_DictSearch search;
+	Tcl_Obj *listObj;
+	int done, len, allocatedMapFlag = 0;
+	/*
+	 * Defaults
+	 */
+	Tcl_Obj *subcmdObj = NULL;
+	Tcl_Obj *mapObj = NULL;
+	int permitPrefix = 1;
+	Tcl_Obj *unknownObj = NULL;
+	Tcl_Obj *paramObj = NULL;
+
+	/*
+	 * Check that we've got option-value pairs... [Bug 1558654]
+	 */
+
+	if ((objc & 1) == 0) {
+	    Tcl_WrongNumArgs(interp, 3, objv, "?option value ...?");
+	    return TCL_ERROR;
+	}
+	objv += 3;
+	objc -= 3;
+
+	/*
+	 * Work out what name to use for the command to create. If supplied,
+	 * it is either fully specified or relative to the current namespace.
+	 * If not supplied, it is exactly the name of the current namespace.
+	 */
+
+	name = nsPtr->fullName;
+
+	/*
+	 * Parse the option list, applying type checks as we go. Note that we
+	 * are not incrementing any reference counts in the objects at this
+	 * stage, so the presence of an option multiple times won't cause any
+	 * memory leaks.
+	 */
+
+	for (; objc>1 ; objc-=2,objv+=2) {
+	    if (Tcl_GetIndexFromObj(interp, objv[0], createOptions, "option",
+		    0, &index) != TCL_OK) {
+		if (allocatedMapFlag) {
+		    Tcl_DecrRefCount(mapObj);
+		}
+		return TCL_ERROR;
+	    }
+	    switch ((enum EnsCreateOpts) index) {
+	    case CRT_CMD:
+		name = TclGetString(objv[1]);
+		continue;
+	    case CRT_SUBCMDS:
+		if (TclListObjLength(interp, objv[1], &len) != TCL_OK) {
+		    if (allocatedMapFlag) {
+			Tcl_DecrRefCount(mapObj);
+		    }
+		    return TCL_ERROR;
+		}
+		subcmdObj = (len > 0 ? objv[1] : NULL);
+		continue;
+	    case CRT_PARAM:
+		if (TclListObjLength(interp, objv[1], &len) != TCL_OK) {
+		    if (allocatedMapFlag) {
+			Tcl_DecrRefCount(mapObj);
+		    }
+		    return TCL_ERROR;
+		}
+		paramObj = (len > 0 ? objv[1] : NULL);
+		continue;
+	    case CRT_MAP: {
+		Tcl_Obj *patchedDict = NULL, *subcmdObj;
+
+		/*
+		 * Verify that the map is sensible.
+		 */
+
+		if (Tcl_DictObjFirst(interp, objv[1], &search,
+			&subcmdObj, &listObj, &done) != TCL_OK) {
+		    if (allocatedMapFlag) {
+			Tcl_DecrRefCount(mapObj);
+		    }
+		    return TCL_ERROR;
+		}
+		if (done) {
+		    mapObj = NULL;
+		    continue;
+		}
+		do {
+		    Tcl_Obj **listv;
+		    const char *cmd;
+
+		    if (TclListObjGetElements(interp, listObj, &len,
+			    &listv) != TCL_OK) {
+			Tcl_DictObjDone(&search);
+			if (patchedDict) {
+			    Tcl_DecrRefCount(patchedDict);
+			}
+			if (allocatedMapFlag) {
+			    Tcl_DecrRefCount(mapObj);
+			}
+			return TCL_ERROR;
+		    }
+		    if (len < 1) {
+			Tcl_SetResult(interp,
+				"ensemble subcommand implementations "
+				"must be non-empty lists", TCL_STATIC);
+			Tcl_DictObjDone(&search);
+			if (patchedDict) {
+			    Tcl_DecrRefCount(patchedDict);
+			}
+			if (allocatedMapFlag) {
+			    Tcl_DecrRefCount(mapObj);
+			}
+			return TCL_ERROR;
+		    }
+		    cmd = TclGetString(listv[0]);
+		    if (!(cmd[0] == ':' && cmd[1] == ':')) {
+			Tcl_Obj *newList = Tcl_NewListObj(len, listv);
+			Tcl_Obj *newCmd = Tcl_NewStringObj(nsPtr->fullName,-1);
+
+			if (nsPtr->parentPtr) {
+			    Tcl_AppendStringsToObj(newCmd, "::", NULL);
+			}
+			Tcl_AppendObjToObj(newCmd, listv[0]);
+			Tcl_ListObjReplace(NULL, newList, 0, 1, 1, &newCmd);
+			if (patchedDict == NULL) {
+			    patchedDict = Tcl_DuplicateObj(objv[1]);
+			}
+			Tcl_DictObjPut(NULL, patchedDict, subcmdObj, newList);
+		    }
+		    Tcl_DictObjNext(&search, &subcmdObj, &listObj, &done);
+		} while (!done);
+
+		if (allocatedMapFlag) {
+		    Tcl_DecrRefCount(mapObj);
+		}
+		mapObj = (patchedDict ? patchedDict : objv[1]);
+		if (patchedDict) {
+		    allocatedMapFlag = 1;
+		}
+		continue;
+	    }
+	    case CRT_PREFIX:
+		if (Tcl_GetBooleanFromObj(interp, objv[1],
+			&permitPrefix) != TCL_OK) {
+		    if (allocatedMapFlag) {
+			Tcl_DecrRefCount(mapObj);
+		    }
+		    return TCL_ERROR;
+		}
+		continue;
+	    case CRT_UNKNOWN:
+		if (TclListObjLength(interp, objv[1], &len) != TCL_OK) {
+		    if (allocatedMapFlag) {
+			Tcl_DecrRefCount(mapObj);
+		    }
+		    return TCL_ERROR;
+		}
+		unknownObj = (len > 0 ? objv[1] : NULL);
+		continue;
+	    }
+	}
+
+	/*
+	 * Create the ensemble. Note that this might delete another ensemble
+	 * linked to the same namespace, so we must be careful. However, we
+	 * should be OK because we only link the namespace into the list once
+	 * we've created it (and after any deletions have occurred.)
+	 */
+
+	token = Tcl_CreateEnsemble(interp, name, NULL,
+		(permitPrefix ? TCL_ENSEMBLE_PREFIX : 0));
+	Tcl_SetEnsembleSubcommandList(interp, token, subcmdObj);
+	Tcl_SetEnsembleMappingDict(interp, token, mapObj);
+	Tcl_SetEnsembleUnknownHandler(interp, token, unknownObj);
+	Tcl_SetEnsembleParameterList(interp, token, paramObj);
+
+	/*
+	 * Tricky! Must ensure that the result is not shared (command delete
+	 * traces could have corrupted the pristine object that we started
+	 * with). [Snit test rename-1.5]
+	 */
+
+	Tcl_ResetResult(interp);
+	Tcl_GetCommandFullName(interp, token, Tcl_GetObjResult(interp));
+	return TCL_OK;
+    }
+
+    case ENS_EXISTS:
+	if (objc != 4) {
+	    Tcl_WrongNumArgs(interp, 3, objv, "cmdname");
+	    return TCL_ERROR;
+	}
+	Tcl_SetObjResult(interp, Tcl_NewBooleanObj(
+		Tcl_FindEnsemble(interp, objv[3], 0) != NULL));
+	return TCL_OK;
+
+    case ENS_CONFIG:
+	if (objc < 4 || (objc != 5 && objc & 1)) {
+	    Tcl_WrongNumArgs(interp, 3, objv,
+		    "cmdname ?-option value ...? ?arg ...?");
+	    return TCL_ERROR;
+	}
+	token = Tcl_FindEnsemble(interp, objv[3], TCL_LEAVE_ERR_MSG);
+	if (token == NULL) {
+	    return TCL_ERROR;
+	}
+
+	if (objc == 5) {
+	    Tcl_Obj *resultObj = NULL;		/* silence gcc 4 warning */
+
+	    if (Tcl_GetIndexFromObj(interp, objv[4], configOptions, "option",
+		    0, &index) != TCL_OK) {
+		return TCL_ERROR;
+	    }
+	    switch ((enum EnsConfigOpts) index) {
+	    case CONF_SUBCMDS:
+		Tcl_GetEnsembleSubcommandList(NULL, token, &resultObj);
+		if (resultObj != NULL) {
+		    Tcl_SetObjResult(interp, resultObj);
+		}
+		break;
+	    case CONF_PARAM:
+		Tcl_GetEnsembleParameterList(NULL, token, &resultObj);
+		if (resultObj != NULL) {
+		    Tcl_SetObjResult(interp, resultObj);
+		}
+		break;
+	    case CONF_MAP:
+		Tcl_GetEnsembleMappingDict(NULL, token, &resultObj);
+		if (resultObj != NULL) {
+		    Tcl_SetObjResult(interp, resultObj);
+		}
+		break;
+	    case CONF_NAMESPACE: {
+		Tcl_Namespace *namespacePtr = NULL; /* silence gcc 4 warning */
+
+		Tcl_GetEnsembleNamespace(NULL, token, &namespacePtr);
+		Tcl_SetResult(interp, ((Namespace *) namespacePtr)->fullName,
+			TCL_VOLATILE);
+		break;
+	    }
+	    case CONF_PREFIX: {
+		int flags = 0;			/* silence gcc 4 warning */
+
+		Tcl_GetEnsembleFlags(NULL, token, &flags);
+		Tcl_SetObjResult(interp,
+			Tcl_NewBooleanObj(flags & TCL_ENSEMBLE_PREFIX));
+		break;
+	    }
+	    case CONF_UNKNOWN:
+		Tcl_GetEnsembleUnknownHandler(NULL, token, &resultObj);
+		if (resultObj != NULL) {
+		    Tcl_SetObjResult(interp, resultObj);
+		}
+		break;
+	    }
+	    return TCL_OK;
+
+	} else if (objc == 4) {
+	    /*
+	     * Produce list of all information.
+	     */
+
+	    Tcl_Obj *resultObj, *tmpObj = NULL;	/* silence gcc 4 warning */
+	    Tcl_Namespace *namespacePtr = NULL;	/* silence gcc 4 warning */
+	    int flags = 0;			/* silence gcc 4 warning */
+
+	    TclNewObj(resultObj);
+
+	    /* -map option */
+	    Tcl_ListObjAppendElement(NULL, resultObj,
+		    Tcl_NewStringObj(configOptions[CONF_MAP], -1));
+	    Tcl_GetEnsembleMappingDict(NULL, token, &tmpObj);
+	    Tcl_ListObjAppendElement(NULL, resultObj,
+		    (tmpObj != NULL) ? tmpObj : Tcl_NewObj());
+
+	    /* -namespace option */
+	    Tcl_ListObjAppendElement(NULL, resultObj,
+		    Tcl_NewStringObj(configOptions[CONF_NAMESPACE], -1));
+	    Tcl_GetEnsembleNamespace(NULL, token, &namespacePtr);
+	    Tcl_ListObjAppendElement(NULL, resultObj,
+		    Tcl_NewStringObj(((Namespace *) namespacePtr)->fullName,
+		    -1));
+
+	    /* -parameters option */
+	    Tcl_ListObjAppendElement(NULL, resultObj,
+		    Tcl_NewStringObj(configOptions[CONF_PARAM], -1));
+	    Tcl_GetEnsembleParameterList(NULL, token, &tmpObj);
+	    Tcl_ListObjAppendElement(NULL, resultObj,
+		    (tmpObj != NULL) ? tmpObj : Tcl_NewObj());
+
+	    /* -prefix option */
+	    Tcl_ListObjAppendElement(NULL, resultObj,
+		    Tcl_NewStringObj(configOptions[CONF_PREFIX], -1));
+	    Tcl_GetEnsembleFlags(NULL, token, &flags);
+	    Tcl_ListObjAppendElement(NULL, resultObj,
+		    Tcl_NewBooleanObj(flags & TCL_ENSEMBLE_PREFIX));
+
+	    /* -subcommands option */
+	    Tcl_ListObjAppendElement(NULL, resultObj,
+		    Tcl_NewStringObj(configOptions[CONF_SUBCMDS], -1));
+	    Tcl_GetEnsembleSubcommandList(NULL, token, &tmpObj);
+	    Tcl_ListObjAppendElement(NULL, resultObj,
+		    (tmpObj != NULL) ? tmpObj : Tcl_NewObj());
+
+	    /* -unknown option */
+	    Tcl_ListObjAppendElement(NULL, resultObj,
+		    Tcl_NewStringObj(configOptions[CONF_UNKNOWN], -1));
+	    Tcl_GetEnsembleUnknownHandler(NULL, token, &tmpObj);
+	    Tcl_ListObjAppendElement(NULL, resultObj,
+		    (tmpObj != NULL) ? tmpObj : Tcl_NewObj());
+
+	    Tcl_SetObjResult(interp, resultObj);
+	    return TCL_OK;
+	} else {
+	    Tcl_DictSearch search;
+	    Tcl_Obj *listObj;
+	    int done, len, allocatedMapFlag = 0;
+	    Tcl_Obj *subcmdObj = NULL, *mapObj = NULL, *paramObj = NULL,
+		    *unknownObj = NULL; /* Defaults, silence gcc 4 warnings */
+	    int permitPrefix, flags = 0;	/* silence gcc 4 warning */
+
+	    Tcl_GetEnsembleSubcommandList(NULL, token, &subcmdObj);
+	    Tcl_GetEnsembleMappingDict(NULL, token, &mapObj);
+	    Tcl_GetEnsembleParameterList(NULL, token, &paramObj);
+	    Tcl_GetEnsembleUnknownHandler(NULL, token, &unknownObj);
+	    Tcl_GetEnsembleFlags(NULL, token, &flags);
+	    permitPrefix = (flags & TCL_ENSEMBLE_PREFIX) != 0;
+
+	    objv += 4;
+	    objc -= 4;
+
+	    /*
+	     * Parse the option list, applying type checks as we go. Note that
+	     * we are not incrementing any reference counts in the objects at
+	     * this stage, so the presence of an option multiple times won't
+	     * cause any memory leaks.
+	     */
+
+	    for (; objc>0 ; objc-=2,objv+=2) {
+		if (Tcl_GetIndexFromObj(interp, objv[0], configOptions,
+			"option", 0, &index) != TCL_OK) {
+		    if (allocatedMapFlag) {
+			Tcl_DecrRefCount(mapObj);
+		    }
+		    return TCL_ERROR;
+		}
+		switch ((enum EnsConfigOpts) index) {
+		case CONF_SUBCMDS:
+		    if (TclListObjLength(interp, objv[1], &len) != TCL_OK) {
+			if (allocatedMapFlag) {
+			    Tcl_DecrRefCount(mapObj);
+			}
+			return TCL_ERROR;
+		    }
+		    subcmdObj = (len > 0 ? objv[1] : NULL);
+		    continue;
+		case CONF_PARAM:
+		    if (TclListObjLength(interp, objv[1], &len) != TCL_OK) {
+			if (allocatedMapFlag) {
+			    Tcl_DecrRefCount(mapObj);
+			}
+			return TCL_ERROR;
+		    }
+		    paramObj = (len > 0 ? objv[1] : NULL);
+		    continue;
+		case CONF_MAP: {
+		    Tcl_Obj *patchedDict = NULL, *subcmdObj;
+
+		    /*
+		     * Verify that the map is sensible.
+		     */
+
+		    if (Tcl_DictObjFirst(interp, objv[1], &search,
+			    &subcmdObj, &listObj, &done) != TCL_OK) {
+			if (allocatedMapFlag) {
+			    Tcl_DecrRefCount(mapObj);
+			}
+			return TCL_ERROR;
+		    }
+		    if (done) {
+			mapObj = NULL;
+			continue;
+		    }
+		    do {
+			Tcl_Obj **listv;
+			const char *cmd;
+
+			if (TclListObjGetElements(interp, listObj, &len,
+				&listv) != TCL_OK) {
+			    Tcl_DictObjDone(&search);
+			    if (patchedDict) {
+				Tcl_DecrRefCount(patchedDict);
+			    }
+			    if (allocatedMapFlag) {
+				Tcl_DecrRefCount(mapObj);
+			    }
+			    return TCL_ERROR;
+			}
+			if (len < 1) {
+			    Tcl_SetResult(interp,
+				    "ensemble subcommand implementations "
+				    "must be non-empty lists", TCL_STATIC);
+			    Tcl_DictObjDone(&search);
+			    if (patchedDict) {
+				Tcl_DecrRefCount(patchedDict);
+			    }
+			    if (allocatedMapFlag) {
+				Tcl_DecrRefCount(mapObj);
+			    }
+			    return TCL_ERROR;
+			}
+			cmd = TclGetString(listv[0]);
+			if (!(cmd[0] == ':' && cmd[1] == ':')) {
+			    Tcl_Obj *newList = Tcl_NewListObj(len, listv);
+			    Tcl_Obj *newCmd =
+				    Tcl_NewStringObj(nsPtr->fullName, -1);
+
+			    if (nsPtr->parentPtr) {
+				Tcl_AppendStringsToObj(newCmd, "::", NULL);
+			    }
+			    Tcl_AppendObjToObj(newCmd, listv[0]);
+			    Tcl_ListObjReplace(NULL, newList, 0,1, 1,&newCmd);
+			    if (patchedDict == NULL) {
+				patchedDict = Tcl_DuplicateObj(objv[1]);
+			    }
+			    Tcl_DictObjPut(NULL, patchedDict, subcmdObj,
+				    newList);
+			}
+			Tcl_DictObjNext(&search, &subcmdObj, &listObj, &done);
+		    } while (!done);
+		    if (allocatedMapFlag) {
+			Tcl_DecrRefCount(mapObj);
+		    }
+		    mapObj = (patchedDict ? patchedDict : objv[1]);
+		    if (patchedDict) {
+			allocatedMapFlag = 1;
+		    }
+		    continue;
+		}
+		case CONF_NAMESPACE:
+		    if (allocatedMapFlag) {
+			Tcl_DecrRefCount(mapObj);
+		    }
+		    Tcl_AppendResult(interp, "option -namespace is read-only",
+			    NULL);
+		    return TCL_ERROR;
+		case CONF_PREFIX:
+		    if (Tcl_GetBooleanFromObj(interp, objv[1],
+			    &permitPrefix) != TCL_OK) {
+			if (allocatedMapFlag) {
+			    Tcl_DecrRefCount(mapObj);
+			}
+			return TCL_ERROR;
+		    }
+		    continue;
+		case CONF_UNKNOWN:
+		    if (TclListObjLength(interp, objv[1], &len) != TCL_OK) {
+			if (allocatedMapFlag) {
+			    Tcl_DecrRefCount(mapObj);
+			}
+			return TCL_ERROR;
+		    }
+		    unknownObj = (len > 0 ? objv[1] : NULL);
+		    continue;
+		}
+	    }
+
+	    /*
+	     * Update the namespace now that we've finished the parsing stage.
+	     */
+
+	    flags = (permitPrefix ? flags|TCL_ENSEMBLE_PREFIX
+		    : flags&~TCL_ENSEMBLE_PREFIX);
+	    Tcl_SetEnsembleSubcommandList(interp, token, subcmdObj);
+	    Tcl_SetEnsembleMappingDict(interp, token, mapObj);
+	    Tcl_SetEnsembleParameterList(interp, token, paramObj);
+	    Tcl_SetEnsembleUnknownHandler(interp, token, unknownObj);
+	    Tcl_SetEnsembleFlags(interp, token, flags);
+	    return TCL_OK;
+	}
+
+    default:
+	Tcl_Panic("unexpected ensemble command");
+    }
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_CreateEnsemble --
+ *
+ *	Create a simple ensemble attached to the given namespace.
+ *
+ * Results:
+ *	The token for the command created.
+ *
+ * Side effects:
+ *	The ensemble is created and marked for compilation.
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_Command
+Tcl_CreateEnsemble(
+    Tcl_Interp *interp,
+    const char *name,
+    Tcl_Namespace *namespacePtr,
+    int flags)
+{
+    Namespace *nsPtr = (Namespace *) namespacePtr;
+    EnsembleConfig *ensemblePtr = (EnsembleConfig *)
+	    ckalloc(sizeof(EnsembleConfig));
+    Tcl_Obj *nameObj = NULL;
+
+    if (nsPtr == NULL) {
+	nsPtr = (Namespace *) TclGetCurrentNamespace(interp);
+    }
+
+    /*
+     * Make the name of the ensemble into a fully qualified name. This might
+     * allocate a temporary object.
+     */
+
+    if (!(name[0] == ':' && name[1] == ':')) {
+	nameObj = Tcl_NewStringObj(nsPtr->fullName, -1);
+	if (nsPtr->parentPtr == NULL) {
+	    Tcl_AppendStringsToObj(nameObj, name, NULL);
+	} else {
+	    Tcl_AppendStringsToObj(nameObj, "::", name, NULL);
+	}
+	Tcl_IncrRefCount(nameObj);
+	name = TclGetString(nameObj);
+    }
+
+    ensemblePtr->nsPtr = nsPtr;
+    ensemblePtr->epoch = 0;
+    Tcl_InitHashTable(&ensemblePtr->subcommandTable, TCL_STRING_KEYS);
+    ensemblePtr->subcommandArrayPtr = NULL;
+    ensemblePtr->subcmdList = NULL;
+    ensemblePtr->subcommandDict = NULL;
+    ensemblePtr->flags = flags;
+    ensemblePtr->numParameters = 0;
+    ensemblePtr->parameterList = NULL;
+    ensemblePtr->unknownHandler = NULL;
+    ensemblePtr->token = Tcl_NRCreateCommand(interp, name,
+	    NsEnsembleImplementationCmd, NsEnsembleImplementationCmdNR,
+	    ensemblePtr, DeleteEnsembleConfig);
+    ensemblePtr->next = (EnsembleConfig *) nsPtr->ensembles;
+    nsPtr->ensembles = (Tcl_Ensemble *) ensemblePtr;
+
+    /*
+     * Trigger an eventual recomputation of the ensemble command set. Note
+     * that this is slightly tricky, as it means that we are not actually
+     * counting the number of namespace export actions, but it is the simplest
+     * way to go!
+     */
+
+    nsPtr->exportLookupEpoch++;
+
+    if (flags & ENSEMBLE_COMPILE) {
+	((Command *) ensemblePtr->token)->compileProc = TclCompileEnsemble;
+    }
+
+    if (nameObj != NULL) {
+	TclDecrRefCount(nameObj);
+    }
+    return ensemblePtr->token;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_SetEnsembleSubcommandList --
+ *
+ *	Set the subcommand list for a particular ensemble.
+ *
+ * Results:
+ *	Tcl result code (error if command token does not indicate an ensemble
+ *	or the subcommand list - if non-NULL - is not a list).
+ *
+ * Side effects:
+ *	The ensemble is updated and marked for recompilation.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_SetEnsembleSubcommandList(
+    Tcl_Interp *interp,
+    Tcl_Command token,
+    Tcl_Obj *subcmdList)
+{
+    Command *cmdPtr = (Command *) token;
+    EnsembleConfig *ensemblePtr;
+    Tcl_Obj *oldList;
+
+    if (cmdPtr->objProc != NsEnsembleImplementationCmd) {
+	Tcl_AppendResult(interp, "command is not an ensemble", NULL);
+	return TCL_ERROR;
+    }
+    if (subcmdList != NULL) {
+	int length;
+
+	if (TclListObjLength(interp, subcmdList, &length) != TCL_OK) {
+	    return TCL_ERROR;
+	}
+	if (length < 1) {
+	    subcmdList = NULL;
+	}
+    }
+
+    ensemblePtr = cmdPtr->objClientData;
+    oldList = ensemblePtr->subcmdList;
+    ensemblePtr->subcmdList = subcmdList;
+    if (subcmdList != NULL) {
+	Tcl_IncrRefCount(subcmdList);
+    }
+    if (oldList != NULL) {
+	TclDecrRefCount(oldList);
+    }
+
+    /*
+     * Trigger an eventual recomputation of the ensemble command set. Note
+     * that this is slightly tricky, as it means that we are not actually
+     * counting the number of namespace export actions, but it is the simplest
+     * way to go!
+     */
+
+    ensemblePtr->nsPtr->exportLookupEpoch++;
+
+    /*
+     * Special hack to make compiling of [info exists] work when the
+     * dictionary is modified.
+     */
+
+    if (cmdPtr->compileProc != NULL) {
+	((Interp *) interp)->compileEpoch++;
+    }
+
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_SetEnsembleParameterList --
+ *
+ *	Set the parameter list for a particular ensemble.
+ *
+ * Results:
+ *	Tcl result code (error if command token does not indicate an ensemble
+ *	or the parameter list - if non-NULL - is not a list).
+ *
+ * Side effects:
+ *	The ensemble is updated and marked for recompilation.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_SetEnsembleParameterList(
+    Tcl_Interp *interp,
+    Tcl_Command token,
+    Tcl_Obj *paramList)
+{
+    Command *cmdPtr = (Command *) token;
+    EnsembleConfig *ensemblePtr;
+    Tcl_Obj *oldList;
+    int length;
+
+    if (cmdPtr->objProc != NsEnsembleImplementationCmd) {
+	Tcl_AppendResult(interp, "command is not an ensemble", NULL);
+	return TCL_ERROR;
+    }
+    if (paramList == NULL) {
+	length = 0;
+    } else {
+	if (TclListObjLength(interp, paramList, &length) != TCL_OK) {
+	    return TCL_ERROR;
+	}
+	if (length < 1) {
+	    paramList = NULL;
+	}
+    }
+
+    ensemblePtr = cmdPtr->objClientData;
+    oldList = ensemblePtr->parameterList;
+    ensemblePtr->parameterList = paramList;
+    if (paramList != NULL) {
+	Tcl_IncrRefCount(paramList);
+    }
+    if (oldList != NULL) {
+	TclDecrRefCount(oldList);
+    }
+    ensemblePtr->numParameters = length;
+
+    /*
+     * Trigger an eventual recomputation of the ensemble command set. Note
+     * that this is slightly tricky, as it means that we are not actually
+     * counting the number of namespace export actions, but it is the simplest
+     * way to go!
+     */
+
+    ensemblePtr->nsPtr->exportLookupEpoch++;
+
+    /*
+     * Special hack to make compiling of [info exists] work when the
+     * dictionary is modified.
+     */
+
+    if (cmdPtr->compileProc != NULL) {
+	((Interp *) interp)->compileEpoch++;
+    }
+
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_SetEnsembleMappingDict --
+ *
+ *	Set the mapping dictionary for a particular ensemble.
+ *
+ * Results:
+ *	Tcl result code (error if command token does not indicate an ensemble
+ *	or the mapping - if non-NULL - is not a dict).
+ *
+ * Side effects:
+ *	The ensemble is updated and marked for recompilation.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_SetEnsembleMappingDict(
+    Tcl_Interp *interp,
+    Tcl_Command token,
+    Tcl_Obj *mapDict)
+{
+    Command *cmdPtr = (Command *) token;
+    EnsembleConfig *ensemblePtr;
+    Tcl_Obj *oldDict;
+
+    if (cmdPtr->objProc != NsEnsembleImplementationCmd) {
+	Tcl_AppendResult(interp, "command is not an ensemble", NULL);
+	return TCL_ERROR;
+    }
+    if (mapDict != NULL) {
+	int size, done;
+	Tcl_DictSearch search;
+	Tcl_Obj *valuePtr;
+
+	if (Tcl_DictObjSize(interp, mapDict, &size) != TCL_OK) {
+	    return TCL_ERROR;
+	}
+
+	for (Tcl_DictObjFirst(NULL, mapDict, &search, NULL, &valuePtr, &done);
+		!done; Tcl_DictObjNext(&search, NULL, &valuePtr, &done)) {
+	    Tcl_Obj *cmdPtr;
+	    const char *bytes;
+
+	    if (Tcl_ListObjIndex(interp, valuePtr, 0, &cmdPtr) != TCL_OK) {
+		Tcl_DictObjDone(&search);
+		return TCL_ERROR;
+	    }
+	    bytes = TclGetString(cmdPtr);
+	    if (bytes[0] != ':' || bytes[1] != ':') {
+		Tcl_AppendResult(interp,
+			"ensemble target is not a fully-qualified command",
+			NULL);
+		Tcl_DictObjDone(&search);
+		return TCL_ERROR;
+	    }
+	}
+
+	if (size < 1) {
+	    mapDict = NULL;
+	}
+    }
+
+    ensemblePtr = cmdPtr->objClientData;
+    oldDict = ensemblePtr->subcommandDict;
+    ensemblePtr->subcommandDict = mapDict;
+    if (mapDict != NULL) {
+	Tcl_IncrRefCount(mapDict);
+    }
+    if (oldDict != NULL) {
+	TclDecrRefCount(oldDict);
+    }
+
+    /*
+     * Trigger an eventual recomputation of the ensemble command set. Note
+     * that this is slightly tricky, as it means that we are not actually
+     * counting the number of namespace export actions, but it is the simplest
+     * way to go!
+     */
+
+    ensemblePtr->nsPtr->exportLookupEpoch++;
+
+    /*
+     * Special hack to make compiling of [info exists] work when the
+     * dictionary is modified.
+     */
+
+    if (cmdPtr->compileProc != NULL) {
+	((Interp *) interp)->compileEpoch++;
+    }
+
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_SetEnsembleUnknownHandler --
+ *
+ *	Set the unknown handler for a particular ensemble.
+ *
+ * Results:
+ *	Tcl result code (error if command token does not indicate an ensemble
+ *	or the unknown handler - if non-NULL - is not a list).
+ *
+ * Side effects:
+ *	The ensemble is updated and marked for recompilation.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_SetEnsembleUnknownHandler(
+    Tcl_Interp *interp,
+    Tcl_Command token,
+    Tcl_Obj *unknownList)
+{
+    Command *cmdPtr = (Command *) token;
+    EnsembleConfig *ensemblePtr;
+    Tcl_Obj *oldList;
+
+    if (cmdPtr->objProc != NsEnsembleImplementationCmd) {
+	Tcl_AppendResult(interp, "command is not an ensemble", NULL);
+	return TCL_ERROR;
+    }
+    if (unknownList != NULL) {
+	int length;
+
+	if (TclListObjLength(interp, unknownList, &length) != TCL_OK) {
+	    return TCL_ERROR;
+	}
+	if (length < 1) {
+	    unknownList = NULL;
+	}
+    }
+
+    ensemblePtr = cmdPtr->objClientData;
+    oldList = ensemblePtr->unknownHandler;
+    ensemblePtr->unknownHandler = unknownList;
+    if (unknownList != NULL) {
+	Tcl_IncrRefCount(unknownList);
+    }
+    if (oldList != NULL) {
+	TclDecrRefCount(oldList);
+    }
+
+    /*
+     * Trigger an eventual recomputation of the ensemble command set. Note
+     * that this is slightly tricky, as it means that we are not actually
+     * counting the number of namespace export actions, but it is the simplest
+     * way to go!
+     */
+
+    ensemblePtr->nsPtr->exportLookupEpoch++;
+
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_SetEnsembleFlags --
+ *
+ *	Set the flags for a particular ensemble.
+ *
+ * Results:
+ *	Tcl result code (error if command token does not indicate an
+ *	ensemble).
+ *
+ * Side effects:
+ *	The ensemble is updated and marked for recompilation.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_SetEnsembleFlags(
+    Tcl_Interp *interp,
+    Tcl_Command token,
+    int flags)
+{
+    Command *cmdPtr = (Command *) token;
+    EnsembleConfig *ensemblePtr;
+    int wasCompiled;
+
+    if (cmdPtr->objProc != NsEnsembleImplementationCmd) {
+	Tcl_AppendResult(interp, "command is not an ensemble", NULL);
+	return TCL_ERROR;
+    }
+
+    ensemblePtr = cmdPtr->objClientData;
+    wasCompiled = ensemblePtr->flags & ENSEMBLE_COMPILE;
+
+    /*
+     * This API refuses to set the ENSEMBLE_DEAD flag...
+     */
+
+    ensemblePtr->flags &= ENSEMBLE_DEAD;
+    ensemblePtr->flags |= flags & ~ENSEMBLE_DEAD;
+
+    /*
+     * Trigger an eventual recomputation of the ensemble command set. Note
+     * that this is slightly tricky, as it means that we are not actually
+     * counting the number of namespace export actions, but it is the simplest
+     * way to go!
+     */
+
+    ensemblePtr->nsPtr->exportLookupEpoch++;
+
+    /*
+     * If the ENSEMBLE_COMPILE flag status was changed, install or remove the
+     * compiler function and bump the interpreter's compilation epoch so that
+     * bytecode gets regenerated.
+     */
+
+    if (flags & ENSEMBLE_COMPILE) {
+	if (!wasCompiled) {
+	    ((Command*) ensemblePtr->token)->compileProc = TclCompileEnsemble;
+	    ((Interp *) interp)->compileEpoch++;
+	}
+    } else {
+	if (wasCompiled) {
+	    ((Command *) ensemblePtr->token)->compileProc = NULL;
+	    ((Interp *) interp)->compileEpoch++;
+	}
+    }
+
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_GetEnsembleSubcommandList --
+ *
+ *	Get the list of subcommands associated with a particular ensemble.
+ *
+ * Results:
+ *	Tcl result code (error if command token does not indicate an
+ *	ensemble). The list of subcommands is returned by updating the
+ *	variable pointed to by the last parameter (NULL if this is to be
+ *	derived from the mapping dictionary or the associated namespace's
+ *	exported commands).
+ *
+ * Side effects:
+ *	None
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_GetEnsembleSubcommandList(
+    Tcl_Interp *interp,
+    Tcl_Command token,
+    Tcl_Obj **subcmdListPtr)
+{
+    Command *cmdPtr = (Command *) token;
+    EnsembleConfig *ensemblePtr;
+
+    if (cmdPtr->objProc != NsEnsembleImplementationCmd) {
+	if (interp != NULL) {
+	    Tcl_AppendResult(interp, "command is not an ensemble", NULL);
+	}
+	return TCL_ERROR;
+    }
+
+    ensemblePtr = cmdPtr->objClientData;
+    *subcmdListPtr = ensemblePtr->subcmdList;
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_GetEnsembleParameterList --
+ *
+ *	Get the list of parameters associated with a particular ensemble.
+ *
+ * Results:
+ *	Tcl result code (error if command token does not indicate an
+ *	ensemble). The list of parameters is returned by updating the
+ *	variable pointed to by the last parameter (NULL if there are
+ *	no parameters).
+ *
+ * Side effects:
+ *	None
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_GetEnsembleParameterList(
+    Tcl_Interp *interp,
+    Tcl_Command token,
+    Tcl_Obj **paramListPtr)
+{
+    Command *cmdPtr = (Command *) token;
+    EnsembleConfig *ensemblePtr;
+
+    if (cmdPtr->objProc != NsEnsembleImplementationCmd) {
+	if (interp != NULL) {
+	    Tcl_AppendResult(interp, "command is not an ensemble", NULL);
+	}
+	return TCL_ERROR;
+    }
+
+    ensemblePtr = cmdPtr->objClientData;
+    *paramListPtr = ensemblePtr->parameterList;
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_GetEnsembleMappingDict --
+ *
+ *	Get the command mapping dictionary associated with a particular
+ *	ensemble.
+ *
+ * Results:
+ *	Tcl result code (error if command token does not indicate an
+ *	ensemble). The mapping dict is returned by updating the variable
+ *	pointed to by the last parameter (NULL if none is installed).
+ *
+ * Side effects:
+ *	None
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_GetEnsembleMappingDict(
+    Tcl_Interp *interp,
+    Tcl_Command token,
+    Tcl_Obj **mapDictPtr)
+{
+    Command *cmdPtr = (Command *) token;
+    EnsembleConfig *ensemblePtr;
+
+    if (cmdPtr->objProc != NsEnsembleImplementationCmd) {
+	if (interp != NULL) {
+	    Tcl_AppendResult(interp, "command is not an ensemble", NULL);
+	}
+	return TCL_ERROR;
+    }
+
+    ensemblePtr = cmdPtr->objClientData;
+    *mapDictPtr = ensemblePtr->subcommandDict;
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_GetEnsembleUnknownHandler --
+ *
+ *	Get the unknown handler associated with a particular ensemble.
+ *
+ * Results:
+ *	Tcl result code (error if command token does not indicate an
+ *	ensemble). The unknown handler is returned by updating the variable
+ *	pointed to by the last parameter (NULL if no handler is installed).
+ *
+ * Side effects:
+ *	None
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_GetEnsembleUnknownHandler(
+    Tcl_Interp *interp,
+    Tcl_Command token,
+    Tcl_Obj **unknownListPtr)
+{
+    Command *cmdPtr = (Command *) token;
+    EnsembleConfig *ensemblePtr;
+
+    if (cmdPtr->objProc != NsEnsembleImplementationCmd) {
+	if (interp != NULL) {
+	    Tcl_AppendResult(interp, "command is not an ensemble", NULL);
+	}
+	return TCL_ERROR;
+    }
+
+    ensemblePtr = cmdPtr->objClientData;
+    *unknownListPtr = ensemblePtr->unknownHandler;
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_GetEnsembleFlags --
+ *
+ *	Get the flags for a particular ensemble.
+ *
+ * Results:
+ *	Tcl result code (error if command token does not indicate an
+ *	ensemble). The flags are returned by updating the variable pointed to
+ *	by the last parameter.
+ *
+ * Side effects:
+ *	None
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_GetEnsembleFlags(
+    Tcl_Interp *interp,
+    Tcl_Command token,
+    int *flagsPtr)
+{
+    Command *cmdPtr = (Command *) token;
+    EnsembleConfig *ensemblePtr;
+
+    if (cmdPtr->objProc != NsEnsembleImplementationCmd) {
+	if (interp != NULL) {
+	    Tcl_AppendResult(interp, "command is not an ensemble", NULL);
+	}
+	return TCL_ERROR;
+    }
+
+    ensemblePtr = cmdPtr->objClientData;
+    *flagsPtr = ensemblePtr->flags;
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_GetEnsembleNamespace --
+ *
+ *	Get the namespace associated with a particular ensemble.
+ *
+ * Results:
+ *	Tcl result code (error if command token does not indicate an
+ *	ensemble). Namespace is returned by updating the variable pointed to
+ *	by the last parameter.
+ *
+ * Side effects:
+ *	None
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_GetEnsembleNamespace(
+    Tcl_Interp *interp,
+    Tcl_Command token,
+    Tcl_Namespace **namespacePtrPtr)
+{
+    Command *cmdPtr = (Command *) token;
+    EnsembleConfig *ensemblePtr;
+
+    if (cmdPtr->objProc != NsEnsembleImplementationCmd) {
+	if (interp != NULL) {
+	    Tcl_AppendResult(interp, "command is not an ensemble", NULL);
+	}
+	return TCL_ERROR;
+    }
+
+    ensemblePtr = cmdPtr->objClientData;
+    *namespacePtrPtr = (Tcl_Namespace *) ensemblePtr->nsPtr;
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_FindEnsemble --
+ *
+ *	Given a command name, get the ensemble token for it, allowing for
+ *	[namespace import]s. [Bug 1017022]
+ *
+ * Results:
+ *	The token for the ensemble command with the given name, or NULL if the
+ *	command either does not exist or is not an ensemble (when an error
+ *	message will be written into the interp if thats non-NULL).
+ *
+ * Side effects:
+ *	None
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_Command
+Tcl_FindEnsemble(
+    Tcl_Interp *interp,		/* Where to do the lookup, and where to write
+				 * the errors if TCL_LEAVE_ERR_MSG is set in
+				 * the flags. */
+    Tcl_Obj *cmdNameObj,	/* Name of command to look up. */
+    int flags)			/* Either 0 or TCL_LEAVE_ERR_MSG; other flags
+				 * are probably not useful. */
+{
+    Command *cmdPtr;
+
+    cmdPtr = (Command *)
+	    Tcl_FindCommand(interp, TclGetString(cmdNameObj), NULL, flags);
+    if (cmdPtr == NULL) {
+	return NULL;
+    }
+
+    if (cmdPtr->objProc != NsEnsembleImplementationCmd) {
+	/*
+	 * Reuse existing infrastructure for following import link chains
+	 * rather than duplicating it.
+	 */
+
+	cmdPtr = (Command *) TclGetOriginalCommand((Tcl_Command) cmdPtr);
+
+	if (cmdPtr == NULL || cmdPtr->objProc != NsEnsembleImplementationCmd){
+	    if (flags & TCL_LEAVE_ERR_MSG) {
+		Tcl_AppendResult(interp, "\"", TclGetString(cmdNameObj),
+			"\" is not an ensemble command", NULL);
+		Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ENSEMBLE",
+			TclGetString(cmdNameObj), NULL);
+	    }
+	    return NULL;
+	}
+    }
+
+    return (Tcl_Command) cmdPtr;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_IsEnsemble --
+ *
+ *	Simple test for ensemble-hood that takes into account imported
+ *	ensemble commands as well.
+ *
+ * Results:
+ *	Boolean value
+ *
+ * Side effects:
+ *	None
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_IsEnsemble(
+    Tcl_Command token)
+{
+    Command *cmdPtr = (Command *) token;
+
+    if (cmdPtr->objProc == NsEnsembleImplementationCmd) {
+	return 1;
+    }
+    cmdPtr = (Command *) TclGetOriginalCommand((Tcl_Command) cmdPtr);
+    if (cmdPtr == NULL || cmdPtr->objProc != NsEnsembleImplementationCmd) {
+	return 0;
+    }
+    return 1;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclMakeEnsemble --
+ *
+ *	Create an ensemble from a table of implementation commands. The
+ *	ensemble will be subject to (limited) compilation if any of the
+ *	implementation commands are compilable.
+ *
+ *	The 'name' parameter may be a single command name or a list if
+ *	creating an ensemble subcommand (see the binary implementation).
+ *
+ *	Currently, the TCL_ENSEMBLE_PREFIX ensemble flag is only used on
+ *	top-level ensemble commands.
+ *
+ * Results:
+ *	Handle for the new ensemble, or NULL on failure.
+ *
+ * Side effects:
+ *	May advance the bytecode compilation epoch.
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_Command
+TclMakeEnsemble(
+    Tcl_Interp *interp,
+    const char *name,		 /* The ensemble name (as explained above) */
+    const EnsembleImplMap map[]) /* The subcommands to create */
+{
+    Tcl_Command ensemble;
+    Tcl_Namespace *ns;
+    Tcl_DString buf;
+    const char **nameParts = NULL;
+    const char *cmdName = NULL;
+    int i, nameCount = 0, ensembleFlags = 0;
+
+    /*
+     * Construct the path for the ensemble namespace and create it.
+     */
+
+    Tcl_DStringInit(&buf);
+    if (name[0] == ':' && name[1] == ':') {
+	/*
+	 * An absolute name, so use it directly.
+	 */
+
+	cmdName = name;
+	Tcl_DStringAppend(&buf, name, -1);
+	ensembleFlags = TCL_ENSEMBLE_PREFIX;
+    } else {
+	/*
+	 * Not an absolute name, so do munging of it. Note that this treats a
+	 * multi-word list differently to a single word.
+	 */
+
+	Tcl_DStringAppend(&buf, "::tcl", -1);
+
+	if (Tcl_SplitList(NULL, name, &nameCount, &nameParts) != TCL_OK) {
+	    Tcl_Panic("invalid ensemble name '%s'", name);
+	}
+
+	for (i = 0; i < nameCount; ++i) {
+	    Tcl_DStringAppend(&buf, "::", 2);
+	    Tcl_DStringAppend(&buf, nameParts[i], -1);
+	}
+    }
+
+    ns = Tcl_FindNamespace(interp, Tcl_DStringValue(&buf), NULL,
+	    TCL_CREATE_NS_IF_UNKNOWN);
+    if (!ns) {
+	Tcl_Panic("unable to find or create %s namespace!",
+		Tcl_DStringValue(&buf));
+    }
+
+    /*
+     * Create the named ensemble in the correct namespace
+     */
+
+    if (cmdName == NULL) {
+	if (nameCount == 1) {
+	    ensembleFlags = TCL_ENSEMBLE_PREFIX;
+	    cmdName = Tcl_DStringValue(&buf) + 5;
+	} else {
+	    ns = ns->parentPtr;
+	    cmdName = nameParts[nameCount - 1];
+	}
+    }
+    ensemble = Tcl_CreateEnsemble(interp, cmdName, ns, ensembleFlags);
+
+    /*
+     * Create the ensemble mapping dictionary and the ensemble command procs.
+     */
+
+    if (ensemble != NULL) {
+	Tcl_Obj *mapDict, *fromObj, *toObj;
+	Command *cmdPtr;
+
+	Tcl_DStringAppend(&buf, "::", 2);
+	TclNewObj(mapDict);
+	for (i=0 ; map[i].name != NULL ; i++) {
+	    fromObj = Tcl_NewStringObj(map[i].name, -1);
+	    TclNewStringObj(toObj, Tcl_DStringValue(&buf),
+		    Tcl_DStringLength(&buf));
+	    Tcl_AppendToObj(toObj, map[i].name, -1);
+	    Tcl_DictObjPut(NULL, mapDict, fromObj, toObj);
+	    if (map[i].proc || map[i].nreProc) {
+		cmdPtr = (Command *)
+			Tcl_NRCreateCommand(interp, TclGetString(toObj),
+			map[i].proc, map[i].nreProc, map[i].clientData, NULL);
+		cmdPtr->compileProc = map[i].compileProc;
+		if (map[i].compileProc != NULL) {
+		    ensembleFlags |= ENSEMBLE_COMPILE;
+		}
+	    }
+	}
+	Tcl_SetEnsembleMappingDict(interp, ensemble, mapDict);
+	if (ensembleFlags & ENSEMBLE_COMPILE) {
+	    Tcl_SetEnsembleFlags(interp, ensemble, ensembleFlags);
+	}
+    }
+
+    Tcl_DStringFree(&buf);
+    if (nameParts != NULL) {
+	Tcl_Free((char *) nameParts);
+    }
+    return ensemble;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * NsEnsembleImplementationCmd --
+ *
+ *	Implements an ensemble of commands (being those exported by a
+ *	namespace other than the global namespace) as a command with the same
+ *	(short) name as the namespace in the parent namespace.
+ *
+ * Results:
+ *	A standard Tcl result code. Will be TCL_ERROR if the command is not an
+ *	unambiguous prefix of any command exported by the ensemble's
+ *	namespace.
+ *
+ * Side effects:
+ *	Depends on the command within the namespace that gets executed. If the
+ *	ensemble itself returns TCL_ERROR, a descriptive error message will be
+ *	placed in the interpreter's result.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+NsEnsembleImplementationCmd(
+    ClientData clientData,
+    Tcl_Interp *interp,
+    int objc,
+    Tcl_Obj *const objv[])
+{
+    return Tcl_NRCallObjProc(interp, NsEnsembleImplementationCmdNR,
+	    clientData, objc, objv);
+}
+
+static int
+NsEnsembleImplementationCmdNR(
+    ClientData clientData,
+    Tcl_Interp *interp,
+    int objc,
+    Tcl_Obj *const objv[])
+{
+    EnsembleConfig *ensemblePtr = clientData;
+				/* The ensemble itself. */
+    Tcl_Obj *prefixObj;		/* An object containing the prefix words of
+				 * the command that implements the
+				 * subcommand. */
+    Tcl_HashEntry *hPtr;	/* Used for efficient lookup of fully
+				 * specified but not yet cached command
+				 * names. */
+    int reparseCount = 0;	/* Number of reparses. */
+
+    /*
+     * Must recheck objc, since numParameters might have changed. Cf. test
+     * namespace-53.9.
+     */
+
+  restartEnsembleParse:
+    if (objc < 2 + ensemblePtr->numParameters) {
+	/*
+	 * We don't have a subcommand argument. Make error message.
+	 */
+
+	Tcl_DString buf;	/* Message being built */
+	Tcl_Obj **elemPtrs;	/* Parameter names */
+	int len;		/* Number of parameters to append */
+
+	Tcl_DStringInit(&buf);
+	if (ensemblePtr->parameterList == NULL) {
+	    len = 0;
+	} else if (TclListObjGetElements(NULL, ensemblePtr->parameterList,
+		&len, &elemPtrs) != TCL_OK) {
+	    Tcl_Panic("List of ensemble parameters is not a list");
+	}
+	for (; len>0; len--,elemPtrs++) {
+	    Tcl_DStringAppend(&buf, Tcl_GetString(*elemPtrs), -1);
+	    Tcl_DStringAppend(&buf, " ", -1);
+	}
+	Tcl_DStringAppend(&buf, "subcommand ?arg ...?", -1);
+	Tcl_WrongNumArgs(interp, 1, objv, Tcl_DStringValue(&buf));
+	Tcl_DStringFree(&buf);
+
+	return TCL_ERROR;
+    }
+
+    if (ensemblePtr->nsPtr->flags & NS_DYING) {
+	/*
+	 * Don't know how we got here, but make things give up quickly.
+	 */
+
+	if (!Tcl_InterpDeleted(interp)) {
+	    Tcl_AppendResult(interp,
+		    "ensemble activated for deleted namespace", NULL);
+	}
+	return TCL_ERROR;
+    }
+
+    /*
+     * Determine if the table of subcommands is right. If so, we can just look
+     * up in there and go straight to dispatch.
+     */
+
+    if (ensemblePtr->epoch == ensemblePtr->nsPtr->exportLookupEpoch) {
+	/*
+	 * Table of subcommands is still valid; therefore there might be a
+	 * valid cache of discovered information which we can reuse. Do the
+	 * check here, and if we're still valid, we can jump straight to the
+	 * part where we do the invocation of the subcommand.
+	 */
+
+	if (objv[1+ensemblePtr->numParameters]->typePtr==&tclEnsembleCmdType){
+	    EnsembleCmdRep *ensembleCmd = objv[1+ensemblePtr->numParameters]
+		    ->internalRep.otherValuePtr;
+
+	    if (ensembleCmd->nsPtr == ensemblePtr->nsPtr &&
+		    ensembleCmd->epoch == ensemblePtr->epoch &&
+		    ensembleCmd->token == ensemblePtr->token) {
+		prefixObj = ensembleCmd->realPrefixObj;
+		Tcl_IncrRefCount(prefixObj);
+		goto runResultingSubcommand;
+	    }
+	}
+    } else {
+	BuildEnsembleConfig(ensemblePtr);
+	ensemblePtr->epoch = ensemblePtr->nsPtr->exportLookupEpoch;
+    }
+
+    /*
+     * Look in the hashtable for the subcommand name; this is the fastest way
+     * of all if there is no cache in operation.
+     */
+
+    hPtr = Tcl_FindHashEntry(&ensemblePtr->subcommandTable,
+	    TclGetString(objv[1 + ensemblePtr->numParameters]));
+    if (hPtr != NULL) {
+	char *fullName = Tcl_GetHashKey(&ensemblePtr->subcommandTable, hPtr);
+
+	prefixObj = Tcl_GetHashValue(hPtr);
+
+	/*
+	 * Cache for later in the subcommand object.
+	 */
+
+	MakeCachedEnsembleCommand(objv[1 + ensemblePtr->numParameters],
+		ensemblePtr, fullName, prefixObj);
+    } else if (!(ensemblePtr->flags & TCL_ENSEMBLE_PREFIX)) {
+	/*
+	 * Could not map, no prefixing, go to unknown/error handling.
+	 */
+
+	goto unknownOrAmbiguousSubcommand;
+    } else {
+	/*
+	 * If we've not already confirmed the command with the hash as part of
+	 * building our export table, we need to scan the sorted array for
+	 * matches.
+	 */
+
+	const char *subcmdName; /* Name of the subcommand, or unique prefix of
+				 * it (will be an error for a non-unique
+				 * prefix). */
+	char *fullName = NULL;	/* Full name of the subcommand. */
+	int stringLength, i;
+	int tableLength = ensemblePtr->subcommandTable.numEntries;
+
+	subcmdName = TclGetString(objv[1 + ensemblePtr->numParameters]);
+	stringLength = objv[1 + ensemblePtr->numParameters]->length;
+	for (i=0 ; i<tableLength ; i++) {
+	    register int cmp = strncmp(subcmdName,
+		    ensemblePtr->subcommandArrayPtr[i],
+		    (unsigned) stringLength);
+
+	    if (cmp == 0) {
+		if (fullName != NULL) {
+		    /*
+		     * Since there's never the exact-match case to worry about
+		     * (hash search filters this), getting here indicates that
+		     * our subcommand is an ambiguous prefix of (at least) two
+		     * exported subcommands, which is an error case.
+		     */
+
+		    goto unknownOrAmbiguousSubcommand;
+		}
+		fullName = ensemblePtr->subcommandArrayPtr[i];
+	    } else if (cmp < 0) {
+		/*
+		 * Because we are searching a sorted table, we can now stop
+		 * searching because we have gone past anything that could
+		 * possibly match.
+		 */
+
+		break;
+	    }
+	}
+	if (fullName == NULL) {
+	    /*
+	     * The subcommand is not a prefix of anything, so bail out!
+	     */
+
+	    goto unknownOrAmbiguousSubcommand;
+	}
+	hPtr = Tcl_FindHashEntry(&ensemblePtr->subcommandTable, fullName);
+	if (hPtr == NULL) {
+	    Tcl_Panic("full name %s not found in supposedly synchronized hash",
+		    fullName);
+	}
+	prefixObj = Tcl_GetHashValue(hPtr);
+
+	/*
+	 * Cache for later in the subcommand object.
+	 */
+
+	MakeCachedEnsembleCommand(objv[1 + ensemblePtr->numParameters],
+		ensemblePtr, fullName, prefixObj);
+    }
+
+    Tcl_IncrRefCount(prefixObj);
+  runResultingSubcommand:
+
+    /*
+     * Do the real work of execution of the subcommand by building an array of
+     * objects (note that this is potentially not the same length as the
+     * number of arguments to this ensemble command), populating it and then
+     * feeding it back through the main command-lookup engine. In theory, we
+     * could look up the command in the namespace ourselves, as we already
+     * have the namespace in which it is guaranteed to exist,
+     *
+     *   ((Q: That's not true if the -map option is used, is it?))
+     *
+     * but we don't do that (the cacheing of the command object used should
+     * help with that.)
+     */
+
+    {
+	Tcl_Obj **prefixObjv;	/* The list of objects to substitute in as the
+				 * target command prefix. */
+	Tcl_Obj *copyPtr;	/* The actual list of words to dispatch to.
+				 * Will be freed by the dispatch engine. */
+	int prefixObjc, copyObjc;
+	Interp *iPtr = (Interp *) interp;
+
+	/*
+	 * Get the prefix that we're rewriting to. To do this we need to
+	 * ensure that the internal representation of the list does not change
+	 * so that we can safely keep the internal representations of the
+	 * elements in the list.
+	 *
+	 * TODO: Use conventional list operations to make this code sane!
+	 */
+
+	TclListObjGetElements(NULL, prefixObj, &prefixObjc, &prefixObjv);
+
+	copyObjc = objc - 2 + prefixObjc;
+	copyPtr = Tcl_NewListObj(copyObjc, NULL);
+	if (copyObjc > 0) {
+	    register Tcl_Obj **copyObjv;
+				/* Space used to construct the list of
+				 * arguments to pass to the command that
+				 * implements the ensemble subcommand. */
+	    register List *listRepPtr = copyPtr->internalRep.twoPtrValue.ptr1;
+	    register int i;
+
+	    listRepPtr->elemCount = copyObjc;
+	    copyObjv = &listRepPtr->elements;
+	    memcpy(copyObjv, prefixObjv, sizeof(Tcl_Obj *) * prefixObjc);
+	    memcpy(copyObjv+prefixObjc, objv+1,
+		    sizeof(Tcl_Obj *) * ensemblePtr->numParameters);
+	    memcpy(copyObjv+prefixObjc+ensemblePtr->numParameters,
+		    objv+ensemblePtr->numParameters+2,
+		    sizeof(Tcl_Obj *) * (objc-ensemblePtr->numParameters-2));
+
+	    for (i=0; i < copyObjc; i++) {
+		Tcl_IncrRefCount(copyObjv[i]);
+	    }
+	}
+	TclDecrRefCount(prefixObj);
+
+	/*
+	 * Record what arguments the script sent in so that things like
+	 * Tcl_WrongNumArgs can give the correct error message. Parameters
+	 * count both as inserted and removed arguments.
+	 */
+
+#if 0
+	if (TclInitRewriteEnsemble(interp, 2 + ensemblePtr->numParameters, prefixObjc + ensemblePtr->numParameters, objv)) {
+	    TclNRAddCallback(interp, TclClearRootEnsemble, NULL, NULL, NULL, NULL);
+	}
+#else
+	if (iPtr->ensembleRewrite.sourceObjs == NULL) {
+	    iPtr->ensembleRewrite.sourceObjs = objv;
+	    iPtr->ensembleRewrite.numRemovedObjs =
+		    2 + ensemblePtr->numParameters;
+	    iPtr->ensembleRewrite.numInsertedObjs =
+		    prefixObjc + ensemblePtr->numParameters;
+	    TclNRAddCallback(interp, TclClearRootEnsemble, NULL, NULL, NULL,
+		    NULL);
+	} else {
+	    register int ni = 2 + ensemblePtr->numParameters
+		    - iPtr->ensembleRewrite.numInsertedObjs;
+				/* Position in objv of new front of insertion
+				 * relative to old one. */
+	    if (ni > 0) {
+		iPtr->ensembleRewrite.numRemovedObjs += ni;
+		iPtr->ensembleRewrite.numInsertedObjs += prefixObjc-1;
+	    } else {
+		iPtr->ensembleRewrite.numInsertedObjs += prefixObjc-2;
+	    }
+	}
+#endif
+
+	/*
+	 * Hand off to the target command.
+	 */
+
+	iPtr->evalFlags |= TCL_EVAL_REDIRECT;
+	return Tcl_NREvalObj(interp, copyPtr, TCL_EVAL_INVOKE);
+    }
+
+  unknownOrAmbiguousSubcommand:
+    /*
+     * Have not been able to match the subcommand asked for with a real
+     * subcommand that we export. See whether a handler has been registered
+     * for dealing with this situation. Will only call (at most) once for any
+     * particular ensemble invocation.
+     */
+
+    if (ensemblePtr->unknownHandler != NULL && reparseCount++ < 1) {
+	switch (EnsembleUnknownCallback(interp, ensemblePtr, objc, objv,
+		&prefixObj)) {
+	case TCL_OK:
+	    goto runResultingSubcommand;
+	case TCL_ERROR:
+	    return TCL_ERROR;
+	case TCL_CONTINUE:
+	    goto restartEnsembleParse;
+	}
+    }
+
+    /*
+     * We cannot determine what subcommand to hand off to, so generate a
+     * (standard) failure message. Note the one odd case compared with
+     * standard ensemble-like command, which is where a namespace has no
+     * exported commands at all...
+     */
+
+    Tcl_ResetResult(interp);
+    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ENSEMBLE",
+	    TclGetString(objv[1+ensemblePtr->numParameters]), NULL);
+    if (ensemblePtr->subcommandTable.numEntries == 0) {
+	Tcl_AppendResult(interp, "unknown subcommand \"",
+		TclGetString(objv[1+ensemblePtr->numParameters]),
+		"\": namespace ", ensemblePtr->nsPtr->fullName,
+		" does not export any commands", NULL);
+	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "SUBCOMMAND",
+		TclGetString(objv[1+ensemblePtr->numParameters]), NULL);
+	return TCL_ERROR;
+    }
+    Tcl_AppendResult(interp, "unknown ",
+	    (ensemblePtr->flags & TCL_ENSEMBLE_PREFIX ? "or ambiguous " : ""),
+	    "subcommand \"", TclGetString(objv[1+ensemblePtr->numParameters]),
+	    "\": must be ", NULL);
+    if (ensemblePtr->subcommandTable.numEntries == 1) {
+	Tcl_AppendResult(interp, ensemblePtr->subcommandArrayPtr[0], NULL);
+    } else {
+	int i;
+
+	for (i=0 ; i<ensemblePtr->subcommandTable.numEntries-1 ; i++) {
+	    Tcl_AppendResult(interp,
+		    ensemblePtr->subcommandArrayPtr[i], ", ", NULL);
+	}
+	Tcl_AppendResult(interp, "or ",
+		ensemblePtr->subcommandArrayPtr[i], NULL);
+    }
+    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "SUBCOMMAND",
+	    TclGetString(objv[1+ensemblePtr->numParameters]), NULL);
+    return TCL_ERROR;
+}
+
+int
+TclClearRootEnsemble(
+    ClientData data[],
+    Tcl_Interp *interp,
+    int result)
+{
+    TclResetRewriteEnsemble(interp, 1);
+    return result;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclInitRewriteEnsemble --
+ *
+ *	Applies a rewrite of arguments so that an ensemble subcommand will
+ *	report error messages correctly for the overall command.
+ *
+ * Results:
+ *	Whether this is the first rewrite applied, a value which must be
+ *	passed to TclResetRewriteEnsemble when undoing this command's
+ *	behaviour.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+TclInitRewriteEnsemble(
+    Tcl_Interp *interp,
+    int numRemoved,
+    int numInserted,
+    Tcl_Obj *const *objv)
+{
+    Interp *iPtr = (Interp *) interp;
+
+    int isRootEnsemble = (iPtr->ensembleRewrite.sourceObjs == NULL);
+
+    if (isRootEnsemble) {
+	iPtr->ensembleRewrite.sourceObjs = objv;
+	iPtr->ensembleRewrite.numRemovedObjs = numRemoved;
+	iPtr->ensembleRewrite.numInsertedObjs = numInserted;
+    } else {
+	int numIns = iPtr->ensembleRewrite.numInsertedObjs;
+
+	if (numIns < numRemoved) {
+	    iPtr->ensembleRewrite.numRemovedObjs += numRemoved - numIns;
+	    iPtr->ensembleRewrite.numInsertedObjs += numInserted - 1;
+	} else {
+	    iPtr->ensembleRewrite.numInsertedObjs += numInserted - numRemoved;
+	}
+    }
+    return isRootEnsemble;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclResetRewriteEnsemble --
+ *
+ *	Removes any rewrites applied to support proper reporting of error
+ *	messages used in ensembles. Should be paired with
+ *	TclInitRewriteEnsemble.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+TclResetRewriteEnsemble(
+    Tcl_Interp *interp,
+    int isRootEnsemble)
+{
+    Interp *iPtr = (Interp *) interp;
+
+    if (isRootEnsemble) {
+	iPtr->ensembleRewrite.sourceObjs = NULL;
+	iPtr->ensembleRewrite.numRemovedObjs = 0;
+	iPtr->ensembleRewrite.numInsertedObjs = 0;
+    }
+}
+
+/*
+ * ----------------------------------------------------------------------
+ *
+ * EnsmebleUnknownCallback --
+ *
+ *	Helper for the ensemble engine that handles the procesing of unknown
+ *	callbacks. See the user documentation of the ensemble unknown handler
+ *	for details; this function is only ever called when such a function is
+ *	defined, and is only ever called once per ensemble dispatch (i.e. if a
+ *	reparse still fails, this isn't called again).
+ *
+ * Results:
+ *	TCL_OK -	*prefixObjPtr contains the command words to dispatch
+ *			to.
+ *	TCL_CONTINUE -	Need to reparse (*prefixObjPtr is invalid).
+ *	TCL_ERROR -	Something went wrong! Error message in interpreter.
+ *
+ * Side effects:
+ *	Calls the Tcl interpreter, so arbitrary.
+ *
+ * ----------------------------------------------------------------------
+ */
+
+static inline int
+EnsembleUnknownCallback(
+    Tcl_Interp *interp,
+    EnsembleConfig *ensemblePtr,
+    int objc,
+    Tcl_Obj *const objv[],
+    Tcl_Obj **prefixObjPtr)
+{
+    int paramc, i, result, prefixObjc;
+    Tcl_Obj **paramv, *unknownCmd, *ensObj;
+    char buf[TCL_INTEGER_SPACE];
+
+    /*
+     * Create the unknown command callback to determine what to do.
+     */
+
+    unknownCmd = Tcl_DuplicateObj(ensemblePtr->unknownHandler);
+    TclNewObj(ensObj);
+    Tcl_GetCommandFullName(interp, ensemblePtr->token, ensObj);
+    Tcl_ListObjAppendElement(NULL, unknownCmd, ensObj);
+    for (i=1 ; i<objc ; i++) {
+	Tcl_ListObjAppendElement(NULL, unknownCmd, objv[i]);
+    }
+    TclListObjGetElements(NULL, unknownCmd, &paramc, &paramv);
+    Tcl_IncrRefCount(unknownCmd);
+
+    /*
+     * Now call the unknown handler. (We don't bother NRE-enabling this; deep
+     * recursing through unknown handlers is horribly perverse.) Note that it
+     * is always an error for an unknown handler to delete its ensemble; don't
+     * do that!
+     */
+
+    Tcl_Preserve(ensemblePtr);
+    ((Interp *) interp)->evalFlags |= TCL_EVAL_REDIRECT;
+    result = Tcl_EvalObjv(interp, paramc, paramv, 0);
+    if ((result == TCL_OK) && (ensemblePtr->flags & ENSEMBLE_DEAD)) {
+	Tcl_SetResult(interp,
+		"unknown subcommand handler deleted its ensemble",
+		TCL_STATIC);
+	result = TCL_ERROR;
+    }
+    Tcl_Release(ensemblePtr);
+
+    /*
+     * If we succeeded, we should either have a list of words that form the
+     * command to be executed, or an empty list. In the empty-list case, the
+     * ensemble is believed to be updated so we should ask the ensemble engine
+     * to reparse the original command.
+     */
+
+    if (result == TCL_OK) {
+	*prefixObjPtr = Tcl_GetObjResult(interp);
+	Tcl_IncrRefCount(*prefixObjPtr);
+	TclDecrRefCount(unknownCmd);
+	Tcl_ResetResult(interp);
+
+	/*
+	 * Namespace is still there. Check if the result is a valid list. If
+	 * it is, and it is non-empty, that list is what we are using as our
+	 * replacement.
+	 */
+
+	if (TclListObjLength(interp, *prefixObjPtr, &prefixObjc) != TCL_OK) {
+	    TclDecrRefCount(*prefixObjPtr);
+	    Tcl_AddErrorInfo(interp, "\n    while parsing result of "
+		    "ensemble unknown subcommand handler");
+	    return TCL_ERROR;
+	}
+	if (prefixObjc > 0) {
+	    return TCL_OK;
+	}
+
+	/*
+	 * Namespace alive & empty result => reparse.
+	 */
+
+	TclDecrRefCount(*prefixObjPtr);
+	return TCL_CONTINUE;
+    }
+
+    /*
+     * Oh no! An exceptional result. Convert to an error.
+     */
+
+    if (!Tcl_InterpDeleted(interp)) {
+	if (result != TCL_ERROR) {
+	    Tcl_ResetResult(interp);
+	    Tcl_SetResult(interp,
+		    "unknown subcommand handler returned bad code: ",
+		    TCL_STATIC);
+	    switch (result) {
+	    case TCL_RETURN:
+		Tcl_AppendResult(interp, "return", NULL);
+		break;
+	    case TCL_BREAK:
+		Tcl_AppendResult(interp, "break", NULL);
+		break;
+	    case TCL_CONTINUE:
+		Tcl_AppendResult(interp, "continue", NULL);
+		break;
+	    default:
+		sprintf(buf, "%d", result);
+		Tcl_AppendResult(interp, buf, NULL);
+	    }
+	    Tcl_AddErrorInfo(interp, "\n    result of "
+		    "ensemble unknown subcommand handler: ");
+	    Tcl_AddErrorInfo(interp, TclGetString(unknownCmd));
+	} else {
+	    Tcl_AddErrorInfo(interp,
+		    "\n    (ensemble unknown subcommand handler)");
+	}
+    }
+    TclDecrRefCount(unknownCmd);
+    return TCL_ERROR;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * MakeCachedEnsembleCommand --
+ *
+ *	Cache what we've computed so far; it's not nice to repeatedly copy
+ *	strings about. Note that to do this, we start by deleting any old
+ *	representation that there was (though if it was an out of date
+ *	ensemble rep, we can skip some of the deallocation process.)
+ *
+ * Results:
+ *	None
+ *
+ * Side effects:
+ *	Alters the internal representation of the first object parameter.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+MakeCachedEnsembleCommand(
+    Tcl_Obj *objPtr,
+    EnsembleConfig *ensemblePtr,
+    const char *subcommandName,
+    Tcl_Obj *prefixObjPtr)
+{
+    register EnsembleCmdRep *ensembleCmd;
+    int length;
+
+    if (objPtr->typePtr == &tclEnsembleCmdType) {
+	ensembleCmd = objPtr->internalRep.otherValuePtr;
+	Tcl_DecrRefCount(ensembleCmd->realPrefixObj);
+	TclNsDecrRefCount(ensembleCmd->nsPtr);
+	ckfree(ensembleCmd->fullSubcmdName);
+    } else {
+	/*
+	 * Kill the old internal rep, and replace it with a brand new one of
+	 * our own.
+	 */
+
+	TclFreeIntRep(objPtr);
+	ensembleCmd = (EnsembleCmdRep *) ckalloc(sizeof(EnsembleCmdRep));
+	objPtr->internalRep.otherValuePtr = ensembleCmd;
+	objPtr->typePtr = &tclEnsembleCmdType;
+    }
+
+    /*
+     * Populate the internal rep.
+     */
+
+    ensembleCmd->nsPtr = ensemblePtr->nsPtr;
+    ensembleCmd->epoch = ensemblePtr->epoch;
+    ensembleCmd->token = ensemblePtr->token;
+    ensemblePtr->nsPtr->refCount++;
+    ensembleCmd->realPrefixObj = prefixObjPtr;
+    length = strlen(subcommandName)+1;
+    ensembleCmd->fullSubcmdName = ckalloc((unsigned) length);
+    memcpy(ensembleCmd->fullSubcmdName, subcommandName, (unsigned) length);
+    Tcl_IncrRefCount(ensembleCmd->realPrefixObj);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * DeleteEnsembleConfig --
+ *
+ *	Destroys the data structure used to represent an ensemble. This is
+ *	called when the ensemble's command is deleted (which happens
+ *	automatically if the ensemble's namespace is deleted.) Maintainers
+ *	should note that ensembles should be deleted by deleting their
+ *	commands.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Memory is (eventually) deallocated.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+DeleteEnsembleConfig(
+    ClientData clientData)
+{
+    EnsembleConfig *ensemblePtr = clientData;
+    Namespace *nsPtr = ensemblePtr->nsPtr;
+    Tcl_HashSearch search;
+    Tcl_HashEntry *hEnt;
+
+    /*
+     * Unlink from the ensemble chain if it has not been marked as having been
+     * done already.
+     */
+
+    if (ensemblePtr->next != ensemblePtr) {
+	EnsembleConfig *ensPtr = (EnsembleConfig *) nsPtr->ensembles;
+
+	if (ensPtr == ensemblePtr) {
+	    nsPtr->ensembles = (Tcl_Ensemble *) ensemblePtr->next;
+	} else {
+	    while (ensPtr != NULL) {
+		if (ensPtr->next == ensemblePtr) {
+		    ensPtr->next = ensemblePtr->next;
+		    break;
+		}
+		ensPtr = ensPtr->next;
+	    }
+	}
+    }
+
+    /*
+     * Mark the namespace as dead so code that uses Tcl_Preserve() can tell
+     * whether disaster happened anyway.
+     */
+
+    ensemblePtr->flags |= ENSEMBLE_DEAD;
+
+    /*
+     * Kill the pointer-containing fields.
+     */
+
+    if (ensemblePtr->subcommandTable.numEntries != 0) {
+	ckfree((char *) ensemblePtr->subcommandArrayPtr);
+    }
+    hEnt = Tcl_FirstHashEntry(&ensemblePtr->subcommandTable, &search);
+    while (hEnt != NULL) {
+	Tcl_Obj *prefixObj = Tcl_GetHashValue(hEnt);
+
+	Tcl_DecrRefCount(prefixObj);
+	hEnt = Tcl_NextHashEntry(&search);
+    }
+    Tcl_DeleteHashTable(&ensemblePtr->subcommandTable);
+    if (ensemblePtr->subcmdList != NULL) {
+	Tcl_DecrRefCount(ensemblePtr->subcmdList);
+    }
+    if (ensemblePtr->parameterList != NULL) {
+	Tcl_DecrRefCount(ensemblePtr->parameterList);
+    }
+    if (ensemblePtr->subcommandDict != NULL) {
+	Tcl_DecrRefCount(ensemblePtr->subcommandDict);
+    }
+    if (ensemblePtr->unknownHandler != NULL) {
+	Tcl_DecrRefCount(ensemblePtr->unknownHandler);
+    }
+
+    /*
+     * Arrange for the structure to be reclaimed. Note that this is complex
+     * because we have to make sure that we can react sensibly when an
+     * ensemble is deleted during the process of initialising the ensemble
+     * (especially the unknown callback.)
+     */
+
+    Tcl_EventuallyFree(ensemblePtr, TCL_DYNAMIC);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * BuildEnsembleConfig --
+ *
+ *	Create the internal data structures that describe how an ensemble
+ *	looks, being a hash mapping from the full command name to the Tcl list
+ *	that describes the implementation prefix words, and a sorted array of
+ *	all the full command names to allow for reasonably efficient
+ *	unambiguous prefix handling.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Reallocates and rebuilds the hash table and array stored at the
+ *	ensemblePtr argument. For large ensembles or large namespaces, this is
+ *	a potentially expensive operation.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+BuildEnsembleConfig(
+    EnsembleConfig *ensemblePtr)
+{
+    Tcl_HashSearch search;	/* Used for scanning the set of commands in
+				 * the namespace that backs up this
+				 * ensemble. */
+    int i, j, isNew;
+    Tcl_HashTable *hash = &ensemblePtr->subcommandTable;
+    Tcl_HashEntry *hPtr;
+
+    if (hash->numEntries != 0) {
+	/*
+	 * Remove pre-existing table.
+	 */
+
+	Tcl_HashSearch search;
+
+	ckfree((char *) ensemblePtr->subcommandArrayPtr);
+	hPtr = Tcl_FirstHashEntry(hash, &search);
+	while (hPtr != NULL) {
+	    Tcl_Obj *prefixObj = Tcl_GetHashValue(hPtr);
+
+	    Tcl_DecrRefCount(prefixObj);
+	    hPtr = Tcl_NextHashEntry(&search);
+	}
+	Tcl_DeleteHashTable(hash);
+	Tcl_InitHashTable(hash, TCL_STRING_KEYS);
+    }
+
+    /*
+     * See if we've got an export list. If so, we will only export exactly
+     * those commands, which may be either implemented by the prefix in the
+     * subcommandDict or mapped directly onto the namespace's commands.
+     */
+
+    if (ensemblePtr->subcmdList != NULL) {
+	Tcl_Obj **subcmdv, *target, *cmdObj, *cmdPrefixObj;
+	int subcmdc;
+
+	TclListObjGetElements(NULL, ensemblePtr->subcmdList, &subcmdc,
+		&subcmdv);
+	for (i=0 ; i<subcmdc ; i++) {
+	    const char *name = TclGetString(subcmdv[i]);
+
+	    hPtr = Tcl_CreateHashEntry(hash, name, &isNew);
+
+	    /*
+	     * Skip non-unique cases.
+	     */
+
+	    if (!isNew) {
+		continue;
+	    }
+
+	    /*
+	     * Look in our dictionary (if present) for the command.
+	     */
+
+	    if (ensemblePtr->subcommandDict != NULL) {
+		Tcl_DictObjGet(NULL, ensemblePtr->subcommandDict, subcmdv[i],
+			&target);
+		if (target != NULL) {
+		    Tcl_SetHashValue(hPtr, target);
+		    Tcl_IncrRefCount(target);
+		    continue;
+		}
+	    }
+
+	    /*
+	     * Not there, so map onto the namespace. Note in this case that we
+	     * do not guarantee that the command is actually there; that is
+	     * the programmer's responsibility (or [::unknown] of course).
+	     */
+
+	    cmdObj = Tcl_NewStringObj(ensemblePtr->nsPtr->fullName, -1);
+	    if (ensemblePtr->nsPtr->parentPtr != NULL) {
+		Tcl_AppendStringsToObj(cmdObj, "::", name, NULL);
+	    } else {
+		Tcl_AppendStringsToObj(cmdObj, name, NULL);
+	    }
+	    cmdPrefixObj = Tcl_NewListObj(1, &cmdObj);
+	    Tcl_SetHashValue(hPtr, cmdPrefixObj);
+	    Tcl_IncrRefCount(cmdPrefixObj);
+	}
+    } else if (ensemblePtr->subcommandDict != NULL) {
+	/*
+	 * No subcmd list, but we do have a mapping dictionary so we should
+	 * use the keys of that. Convert the dictionary's contents into the
+	 * form required for the ensemble's internal hashtable.
+	 */
+
+	Tcl_DictSearch dictSearch;
+	Tcl_Obj *keyObj, *valueObj;
+	int done;
+
+	Tcl_DictObjFirst(NULL, ensemblePtr->subcommandDict, &dictSearch,
+		&keyObj, &valueObj, &done);
+	while (!done) {
+	    const char *name = TclGetString(keyObj);
+
+	    hPtr = Tcl_CreateHashEntry(hash, name, &isNew);
+	    Tcl_SetHashValue(hPtr, valueObj);
+	    Tcl_IncrRefCount(valueObj);
+	    Tcl_DictObjNext(&dictSearch, &keyObj, &valueObj, &done);
+	}
+    } else {
+	/*
+	 * Discover what commands are actually exported by the namespace.
+	 * What we have is an array of patterns and a hash table whose keys
+	 * are the command names exported by the namespace (the contents do
+	 * not matter here.) We must find out what commands are actually
+	 * exported by filtering each command in the namespace against each of
+	 * the patterns in the export list. Note that we use an intermediate
+	 * hash table to make memory management easier, and because that makes
+	 * exact matching far easier too.
+	 *
+	 * Suggestion for future enhancement: compute the unique prefixes and
+	 * place them in the hash too, which should make for even faster
+	 * matching.
+	 */
+
+	hPtr = Tcl_FirstHashEntry(&ensemblePtr->nsPtr->cmdTable, &search);
+	for (; hPtr!= NULL ; hPtr=Tcl_NextHashEntry(&search)) {
+	    char *nsCmdName =		/* Name of command in namespace. */
+		    Tcl_GetHashKey(&ensemblePtr->nsPtr->cmdTable, hPtr);
+
+	    for (i=0 ; i<ensemblePtr->nsPtr->numExportPatterns ; i++) {
+		if (Tcl_StringMatch(nsCmdName,
+			ensemblePtr->nsPtr->exportArrayPtr[i])) {
+		    hPtr = Tcl_CreateHashEntry(hash, nsCmdName, &isNew);
+
+		    /*
+		     * Remember, hash entries have a full reference to the
+		     * substituted part of the command (as a list) as their
+		     * content!
+		     */
+
+		    if (isNew) {
+			Tcl_Obj *cmdObj, *cmdPrefixObj;
+
+			TclNewObj(cmdObj);
+			Tcl_AppendStringsToObj(cmdObj,
+				ensemblePtr->nsPtr->fullName,
+				(ensemblePtr->nsPtr->parentPtr ? "::" : ""),
+				nsCmdName, NULL);
+			cmdPrefixObj = Tcl_NewListObj(1, &cmdObj);
+			Tcl_SetHashValue(hPtr, cmdPrefixObj);
+			Tcl_IncrRefCount(cmdPrefixObj);
+		    }
+		    break;
+		}
+	    }
+	}
+    }
+
+    if (hash->numEntries == 0) {
+	ensemblePtr->subcommandArrayPtr = NULL;
+	return;
+    }
+
+    /*
+     * Create a sorted array of all subcommands in the ensemble; hash tables
+     * are all very well for a quick look for an exact match, but they can't
+     * determine things like whether a string is a prefix of another (not
+     * without lots of preparation anyway) and they're no good for when we're
+     * generating the error message either.
+     *
+     * We do this by filling an array with the names (we use the hash keys
+     * directly to save a copy, since any time we change the array we change
+     * the hash too, and vice versa) and running quicksort over the array.
+     */
+
+    ensemblePtr->subcommandArrayPtr = (char **)
+	    ckalloc(sizeof(char *) * hash->numEntries);
+
+    /*
+     * Fill array from both ends as this makes us less likely to end up with
+     * performance problems in qsort(), which is good. Note that doing this
+     * makes this code much more opaque, but the naive alternatve:
+     *
+     * for (hPtr=Tcl_FirstHashEntry(hash,&search),i=0 ;
+     *	       hPtr!=NULL ; hPtr=Tcl_NextHashEntry(&search),i++) {
+     *     ensemblePtr->subcommandArrayPtr[i] = Tcl_GetHashKey(hash, &hPtr);
+     * }
+     *
+     * can produce long runs of precisely ordered table entries when the
+     * commands in the namespace are declared in a sorted fashion (an ordering
+     * some people like) and the hashing functions (or the command names
+     * themselves) are fairly unfortunate. By filling from both ends, it
+     * requires active malice (and probably a debugger) to get qsort() to have
+     * awful runtime behaviour.
+     */
+
+    i = 0;
+    j = hash->numEntries;
+    hPtr = Tcl_FirstHashEntry(hash, &search);
+    while (hPtr != NULL) {
+	ensemblePtr->subcommandArrayPtr[i++] = Tcl_GetHashKey(hash, hPtr);
+	hPtr = Tcl_NextHashEntry(&search);
+	if (hPtr == NULL) {
+	    break;
+	}
+	ensemblePtr->subcommandArrayPtr[--j] = Tcl_GetHashKey(hash, hPtr);
+	hPtr = Tcl_NextHashEntry(&search);
+    }
+    if (hash->numEntries > 1) {
+	qsort(ensemblePtr->subcommandArrayPtr, (unsigned) hash->numEntries,
+		sizeof(char *), NsEnsembleStringOrder);
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * NsEnsembleStringOrder --
+ *
+ *	Helper function to compare two pointers to two strings for use with
+ *	qsort().
+ *
+ * Results:
+ *	-1 if the first string is smaller, 1 if the second string is smaller,
+ *	and 0 if they are equal.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+NsEnsembleStringOrder(
+    const void *strPtr1,
+    const void *strPtr2)
+{
+    return strcmp(*(const char **)strPtr1, *(const char **)strPtr2);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * FreeEnsembleCmdRep --
+ *
+ *	Destroys the internal representation of a Tcl_Obj that has been
+ *	holding information about a command in an ensemble.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Memory is deallocated. If this held the last reference to a
+ *	namespace's main structure, that main structure will also be
+ *	destroyed.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+FreeEnsembleCmdRep(
+    Tcl_Obj *objPtr)
+{
+    EnsembleCmdRep *ensembleCmd = objPtr->internalRep.otherValuePtr;
+
+    Tcl_DecrRefCount(ensembleCmd->realPrefixObj);
+    ckfree(ensembleCmd->fullSubcmdName);
+    TclNsDecrRefCount(ensembleCmd->nsPtr);
+    ckfree((char *) ensembleCmd);
+    objPtr->typePtr = NULL;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * DupEnsembleCmdRep --
+ *
+ *	Makes one Tcl_Obj into a copy of another that is a subcommand of an
+ *	ensemble.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Memory is allocated, and the namespace that the ensemble is built on
+ *	top of gains another reference.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+DupEnsembleCmdRep(
+    Tcl_Obj *objPtr,
+    Tcl_Obj *copyPtr)
+{
+    EnsembleCmdRep *ensembleCmd = objPtr->internalRep.otherValuePtr;
+    EnsembleCmdRep *ensembleCopy = (EnsembleCmdRep *)
+	    ckalloc(sizeof(EnsembleCmdRep));
+    int length = strlen(ensembleCmd->fullSubcmdName);
+
+    copyPtr->typePtr = &tclEnsembleCmdType;
+    copyPtr->internalRep.otherValuePtr = ensembleCopy;
+    ensembleCopy->nsPtr = ensembleCmd->nsPtr;
+    ensembleCopy->epoch = ensembleCmd->epoch;
+    ensembleCopy->token = ensembleCmd->token;
+    ensembleCopy->nsPtr->refCount++;
+    ensembleCopy->realPrefixObj = ensembleCmd->realPrefixObj;
+    Tcl_IncrRefCount(ensembleCopy->realPrefixObj);
+    ensembleCopy->fullSubcmdName = ckalloc((unsigned) length+1);
+    memcpy(ensembleCopy->fullSubcmdName, ensembleCmd->fullSubcmdName,
+	    (unsigned) length+1);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * StringOfEnsembleCmdRep --
+ *
+ *	Creates a string representation of a Tcl_Obj that holds a subcommand
+ *	of an ensemble.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	The object gains a string (UTF-8) representation.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+StringOfEnsembleCmdRep(
+    Tcl_Obj *objPtr)
+{
+    EnsembleCmdRep *ensembleCmd = objPtr->internalRep.otherValuePtr;
+    int length = strlen(ensembleCmd->fullSubcmdName);
+
+    objPtr->length = length;
+    objPtr->bytes = ckalloc((unsigned) length+1);
+    memcpy(objPtr->bytes, ensembleCmd->fullSubcmdName, (unsigned) length+1);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclCompileEnsemble --
+ *
+ *	Procedure called to compile an ensemble command. Note that most
+ *	ensembles are not compiled, since modifying a compiled ensemble causes
+ *	a invalidation of all existing bytecode (expensive!) which is not
+ *	normally warranted.
+ *
+ * Results:
+ * 	Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
+ * 	evaluation to runtime.
+ *
+ * Side effects:
+ *	Instructions are added to envPtr to execute the subcommands of the
+ *	ensemble at runtime if a compile-time mapping is possible.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+TclCompileEnsemble(
+    Tcl_Interp *interp,		/* Used for error reporting. */
+    Tcl_Parse *parsePtr,	/* Points to a parse structure for the command
+				 * created by Tcl_ParseCommand. */
+    Command *cmdPtr,		/* Points to defintion of command being
+				 * compiled. */
+    CompileEnv *envPtr)		/* Holds resulting instructions. */
+{
+    Tcl_Token *tokenPtr;
+    Tcl_Obj *mapObj, *subcmdObj, *targetCmdObj, *listObj, **elems;
+    Tcl_Command ensemble = (Tcl_Command) cmdPtr;
+    Tcl_Parse synthetic;
+    int len, numBytes, result, flags = 0, i;
+    const char *word;
+
+    if (parsePtr->numWords < 2) {
+	return TCL_ERROR;
+    }
+
+    tokenPtr = TokenAfter(parsePtr->tokenPtr);
+    if (tokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
+	/*
+	 * Too hard.
+	 */
+
+	return TCL_ERROR;
+    }
+
+    word = tokenPtr[1].start;
+    numBytes = tokenPtr[1].size;
+
+    /*
+     * There's a sporting chance we'll be able to compile this. But now we
+     * must check properly. To do that, check that we're compiling an ensemble
+     * that has a compilable command as its appropriate subcommand.
+     */
+
+    if (Tcl_GetEnsembleMappingDict(NULL, ensemble, &mapObj) != TCL_OK
+	    || mapObj == NULL) {
+	/*
+	 * Either not an ensemble or a mapping isn't installed. Crud. Too hard
+	 * to proceed.
+	 */
+
+	return TCL_ERROR;
+    }
+
+    /*
+     * Also refuse to compile anything that uses a formal parameter list for
+     * now, on the grounds that it is too complex.
+     */
+
+    if (Tcl_GetEnsembleParameterList(NULL, ensemble, &listObj) != TCL_OK
+	    || listObj != NULL) {
+	/*
+	 * Figuring out how to compile this has become too much. Bail out.
+	 */
+
+	return TCL_ERROR;
+    }
+
+    /*
+     * Next, get the flags. We need them on several code paths.
+     */
+
+    (void) Tcl_GetEnsembleFlags(NULL, ensemble, &flags);
+
+    /*
+     * Check to see if there's also a subcommand list; must check to see if
+     * the subcommand we are calling is in that list if it exists, since that
+     * list filters the entries in the map.
+     */
+
+    (void) Tcl_GetEnsembleSubcommandList(NULL, ensemble, &listObj);
+    if (listObj != NULL) {
+	int sclen;
+	const char *str;
+	Tcl_Obj *matchObj = NULL;
+
+	if (Tcl_ListObjGetElements(NULL, listObj, &len, &elems) != TCL_OK) {
+	    return TCL_ERROR;
+	}
+	for (i=0 ; i<len ; i++) {
+	    str = Tcl_GetStringFromObj(elems[i], &sclen);
+	    if (sclen==numBytes && !memcmp(word, str, (unsigned) numBytes)) {
+		/*
+		 * Exact match! Excellent!
+		 */
+
+		result = Tcl_DictObjGet(NULL, mapObj,elems[i], &targetCmdObj);
+		if (result != TCL_OK || targetCmdObj == NULL) {
+		    return TCL_ERROR;
+		}
+		goto doneMapLookup;
+	    }
+
+	    /*
+	     * Check to see if we've got a prefix match. A single prefix match
+	     * is fine, and allows us to refine our dictionary lookup, but
+	     * multiple prefix matches is a Bad Thing and will prevent us from
+	     * making progress. Note that we cannot do the lookup immediately
+	     * in the prefix case; might be another entry later in the list
+	     * that causes things to fail.
+	     */
+
+	    if ((flags & TCL_ENSEMBLE_PREFIX)
+		    && strncmp(word, str, (unsigned) numBytes) == 0) {
+		if (matchObj != NULL) {
+		    return TCL_ERROR;
+		}
+		matchObj = elems[i];
+	    }
+	}
+	if (matchObj != NULL) {
+	    result = Tcl_DictObjGet(NULL, mapObj, matchObj, &targetCmdObj);
+	    if (result != TCL_OK || targetCmdObj == NULL) {
+		return TCL_ERROR;
+	    }
+	    goto doneMapLookup;
+	}
+	return TCL_ERROR;
+    } else {
+	/*
+	 * No map, so check the dictionary directly.
+	 */
+
+	TclNewStringObj(subcmdObj, word, numBytes);
+	result = Tcl_DictObjGet(NULL, mapObj, subcmdObj, &targetCmdObj);
+	TclDecrRefCount(subcmdObj);
+	if (result == TCL_OK && targetCmdObj != NULL) {
+	    /*
+	     * Got it. Skip the fiddling around with prefixes.
+	     */
+
+	    goto doneMapLookup;
+	}
+
+	/*
+	 * We've not literally got a valid subcommand. But maybe we have a
+	 * prefix. Check if prefix matches are allowed.
+	 */
+
+	if (flags & TCL_ENSEMBLE_PREFIX) {
+	    Tcl_DictSearch s;
+	    int done, matched;
+	    Tcl_Obj *tmpObj;
+
+	    /*
+	     * Iterate over the keys in the dictionary, checking to see if
+	     * we're a prefix.
+	     */
+
+	    Tcl_DictObjFirst(NULL,mapObj,&s,&subcmdObj,&tmpObj,&done);
+	    matched = 0;
+	    while (!done) {
+		if (strncmp(TclGetString(subcmdObj), word,
+			(unsigned) numBytes) == 0) {
+		    if (matched++) {
+			/*
+			 * Must have matched twice! Not unique, so no point
+			 * looking further.
+			 */
+
+			break;
+		    }
+		    targetCmdObj = tmpObj;
+		}
+		Tcl_DictObjNext(&s, &subcmdObj, &tmpObj, &done);
+	    }
+	    Tcl_DictObjDone(&s);
+
+	    /*
+	     * If we have anything other than a single match, we've failed the
+	     * unique prefix check.
+	     */
+
+	    if (matched != 1) {
+		return TCL_ERROR;
+	    }
+	} else {
+	    return TCL_ERROR;
+	}
+    }
+
+    /*
+     * OK, we definitely map to something. But what?
+     *
+     * The command we map to is the first word out of the map element. Note
+     * that we also reject dealing with multi-element rewrites if we are in a
+     * safe interpreter, as there is otherwise a (highly gnarly!) way to make
+     * Tcl crash open to exploit.
+     */
+
+  doneMapLookup:
+    if (Tcl_ListObjGetElements(NULL, targetCmdObj, &len, &elems) != TCL_OK) {
+	return TCL_ERROR;
+    }
+    if (len > 1 && Tcl_IsSafe(interp)) {
+	return TCL_ERROR;
+    }
+    targetCmdObj = elems[0];
+
+    Tcl_IncrRefCount(targetCmdObj);
+    cmdPtr = (Command *) Tcl_GetCommandFromObj(interp, targetCmdObj);
+    TclDecrRefCount(targetCmdObj);
+    if (cmdPtr == NULL || cmdPtr->compileProc == NULL) {
+	/*
+	 * Maps to an undefined command or a command without a compiler.
+	 * Cannot compile.
+	 */
+
+	return TCL_ERROR;
+    }
+
+    /*
+     * Now we've done the mapping process, can now actually try to compile.
+     * We do this by handing off to the subcommand's actual compiler. But to
+     * do that, we have to perform some trickery to rewrite the arguments.
+     */
+
+    TclParseInit(interp, NULL, 0, &synthetic);
+    synthetic.numWords = parsePtr->numWords - 2 + len;
+    TclGrowParseTokenArray(&synthetic, 2*len);
+    synthetic.numTokens = 2*len;
+
+    /*
+     * Now we have the space to work in, install something rewritten. Note
+     * that we are here praying for all our might that none of these words are
+     * a script; the error detection code will crash if that happens and there
+     * is nothing we can do to avoid it!
+     */
+
+    for (i=0 ; i<len ; i++) {
+	int sclen;
+	const char *str = Tcl_GetStringFromObj(elems[i], &sclen);
+
+	synthetic.tokenPtr[2*i].type = TCL_TOKEN_SIMPLE_WORD;
+	synthetic.tokenPtr[2*i].start = str;
+	synthetic.tokenPtr[2*i].size = sclen;
+	synthetic.tokenPtr[2*i].numComponents = 1;
+
+	synthetic.tokenPtr[2*i+1].type = TCL_TOKEN_TEXT;
+	synthetic.tokenPtr[2*i+1].start = str;
+	synthetic.tokenPtr[2*i+1].size = sclen;
+	synthetic.tokenPtr[2*i+1].numComponents = 0;
+    }
+
+    /*
+     * Copy over the real argument tokens.
+     */
+
+    for (i=len; i<synthetic.numWords; i++) {
+	int toCopy;
+
+	tokenPtr = TokenAfter(tokenPtr);
+	toCopy = tokenPtr->numComponents + 1;
+	TclGrowParseTokenArray(&synthetic, toCopy);
+	memcpy(synthetic.tokenPtr + synthetic.numTokens, tokenPtr,
+		sizeof(Tcl_Token) * toCopy);
+	synthetic.numTokens += toCopy;
+    }
+
+    /*
+     * Hand off compilation to the subcommand compiler. At last!
+     */
+
+    result = cmdPtr->compileProc(interp, &synthetic, cmdPtr, envPtr);
+
+    /*
+     * Clean up if necessary.
+     */
+
+    Tcl_FreeParse(&synthetic);
+    return result;
+}
+
+/*
+ * Local Variables:
+ * mode: c
+ * c-basic-offset: 4
+ * fill-column: 78
+ * End:
+ */