/*
* tclResolve.c --
*
* Contains hooks for customized command/variable name resolution
* schemes. These hooks allow extensions like [incr Tcl] to add their own
* name resolution rules to the Tcl language. Rules can be applied to a
* particular namespace, to the interpreter as a whole, or both.
*
* Copyright (c) 1998 Lucent Technologies, Inc.
*
* See the file "license.terms" for information on usage and redistribution of
* this file, and for a DISCLAIMER OF ALL WARRANTIES.
*
* RCS: @(#) $Id: tclResolve.c,v 1.9 2007/04/05 13:20:49 dkf Exp $
*/
#include "tclInt.h"
/*
* Declarations for functions local to this file:
*/
static void BumpCmdRefEpochs(Namespace *nsPtr);
/*
*----------------------------------------------------------------------
*
* Tcl_AddInterpResolvers --
*
* Adds a set of command/variable resolution functions to an interpreter.
* These functions are consulted when commands are resolved in
* Tcl_FindCommand, and when variables are resolved in TclLookupVar and
* LookupCompiledLocal. Each namespace may also have its own set of
* resolution functions which take precedence over those for the
* interpreter.
*
* When a name is resolved, it is handled as follows. First, the name is
* passed to the resolution functions for the namespace. If not resolved,
* the name is passed to each of the resolution functions added to the
* interpreter. Finally, if still not resolved, the name is handled using
* the default Tcl rules for name resolution.
*
* Results:
* Returns pointers to the current name resolution functions in the
* cmdProcPtr, varProcPtr and compiledVarProcPtr arguments.
*
* Side effects:
* If a compiledVarProc is specified, this function bumps the
* compileEpoch for the interpreter, forcing all code to be recompiled.
* If a cmdProc is specified, this function bumps the cmdRefEpoch in all
* namespaces, forcing commands to be resolved again using the new rules.
*
*----------------------------------------------------------------------
*/
void
Tcl_AddInterpResolvers(
Tcl_Interp *interp, /* Interpreter whose name resolution rules are
* being modified. */
CONST char *name, /* Name of this resolution scheme. */
Tcl_ResolveCmdProc *cmdProc,/* New function for command resolution. */
Tcl_ResolveVarProc *varProc,/* Function for variable resolution at
* runtime. */
Tcl_ResolveCompiledVarProc *compiledVarProc)
/* Function for variable resolution at compile
* time. */
{
Interp *iPtr = (Interp *) interp;
ResolverScheme *resPtr;
/*
* Since we're adding a new name resolution scheme, we must force all code
* to be recompiled to use the new scheme. If there are new compiled
* variable resolution rules, bump the compiler epoch to invalidate
* compiled code. If there are new command resolution rules, bump the
* cmdRefEpoch in all namespaces.
*/
if (compiledVarProc) {
iPtr->compileEpoch++;
}
if (cmdProc) {
BumpCmdRefEpochs(iPtr->globalNsPtr);
}
/*
* Look for an existing scheme with the given name. If found, then replace
* its rules.
*/
for (resPtr=iPtr->resolverPtr ; resPtr!=NULL ; resPtr=resPtr->nextPtr) {
if (*name == *resPtr->name && strcmp(name, resPtr->name) == 0) {
resPtr->cmdResProc = cmdProc;
resPtr->varResProc = varProc;
resPtr->compiledVarResProc = compiledVarProc;
return;
}
}
/*
* Otherwise, this is a new scheme. Add it to the FRONT of the linked
* list, so that it overrides existing schemes.
*/
resPtr = (ResolverScheme *) ckalloc(sizeof(ResolverScheme));
resPtr->name = (char *) ckalloc((unsigned)(strlen(name) + 1));
strcpy(resPtr->name, name);
resPtr->cmdResProc = cmdProc;
resPtr->varResProc = varProc;
resPtr->compiledVarResProc = compiledVarProc;
resPtr->nextPtr = iPtr->resolverPtr;
iPtr->resolverPtr = resPtr;
}
/*
*----------------------------------------------------------------------
*
* Tcl_GetInterpResolvers --
*
* Looks for a set of command/variable resolution functions with the
* given name in an interpreter. These functions are registered by
* calling Tcl_AddInterpResolvers.
*
* Results:
* If the name is recognized, this function returns non-zero, along with
* pointers to the name resolution functions in the Tcl_ResolverInfo
* structure. If the name is not recognized, this function returns zero.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
int
Tcl_GetInterpResolvers(
Tcl_Interp *interp, /* Interpreter whose name resolution rules are
* being queried. */
CONST char *name, /* Look for a scheme with this name. */
Tcl_ResolverInfo *resInfoPtr)
/* Returns pointers to the functions, if
* found */
{
Interp *iPtr = (Interp *) interp;
ResolverScheme *resPtr;
/*
* Look for an existing scheme with the given name. If found, then return
* pointers to its functions.
*/
for (resPtr=iPtr->resolverPtr ; resPtr!=NULL ; resPtr=resPtr->nextPtr) {
if (*name == *resPtr->name && strcmp(name, resPtr->name) == 0) {
resInfoPtr->cmdResProc = resPtr->cmdResProc;
resInfoPtr->varResProc = resPtr->varResProc;
resInfoPtr->compiledVarResProc = resPtr->compiledVarResProc;
return 1;
}
}
return 0;
}
/*
*----------------------------------------------------------------------
*
* Tcl_RemoveInterpResolvers --
*
* Removes a set of command/variable resolution functions previously
* added by Tcl_AddInterpResolvers. The next time a command/variable name
* is resolved, these functions won't be consulted.
*
* Results:
* Returns non-zero if the name was recognized and the resolution scheme
* was deleted. Returns zero otherwise.
*
* Side effects:
* If a scheme with a compiledVarProc was deleted, this function bumps
* the compileEpoch for the interpreter, forcing all code to be
* recompiled. If a scheme with a cmdProc was deleted, this function
* bumps the cmdRefEpoch in all namespaces, forcing commands to be
* resolved again using the new rules.
*
*----------------------------------------------------------------------
*/
int
Tcl_RemoveInterpResolvers(
Tcl_Interp *interp, /* Interpreter whose name resolution rules are
* being modified. */
CONST char *name) /* Name of the scheme to be removed. */
{
Interp *iPtr = (Interp *) interp;
ResolverScheme **prevPtrPtr, *resPtr;
/*
* Look for an existing scheme with the given name.
*/
prevPtrPtr = &iPtr->resolverPtr;
for (resPtr=iPtr->resolverPtr ; resPtr!=NULL ; resPtr=resPtr->nextPtr) {
if (*name == *resPtr->name && strcmp(name, resPtr->name) == 0) {
break;
}
prevPtrPtr = &resPtr->nextPtr;
}
/*
* If we found the scheme, delete it.
*/
if (resPtr) {
/*
* If we're deleting a scheme with compiled variable resolution rules,
* bump the compiler epoch to invalidate compiled code. If we're
* deleting a scheme with command resolution rules, bump the
* cmdRefEpoch in all namespaces.
*/
if (resPtr->compiledVarResProc) {
iPtr->compileEpoch++;
}
if (resPtr->cmdResProc) {
BumpCmdRefEpochs(iPtr->globalNsPtr);
}
*prevPtrPtr = resPtr->nextPtr;
ckfree(resPtr->name);
ckfree((char *) resPtr);
return 1;
}
return 0;
}
/*
*----------------------------------------------------------------------
*
* BumpCmdRefEpochs --
*
* This function is used to bump the cmdRefEpoch counters in the
* specified namespace and all of its child namespaces. It is used
* whenever name resolution schemes are added/removed from an
* interpreter, to invalidate all command references.
*
* Results:
* None.
*
* Side effects:
* Bumps the cmdRefEpoch in the specified namespace and its children,
* recursively.
*
*----------------------------------------------------------------------
*/
static void
BumpCmdRefEpochs(
Namespace *nsPtr) /* Namespace being modified. */
{
Tcl_HashEntry *entry;
Tcl_HashSearch search;
nsPtr->cmdRefEpoch++;
for (entry = Tcl_FirstHashEntry(&nsPtr->childTable, &search);
entry != NULL; entry = Tcl_NextHashEntry(&search)) {
Namespace *childNsPtr = (Namespace *) Tcl_GetHashValue(entry);
BumpCmdRefEpochs(childNsPtr);
}
TclInvalidateNsPath(nsPtr);
}
/*
*----------------------------------------------------------------------
*
* Tcl_SetNamespaceResolvers --
*
* Sets the command/variable resolution functions for a namespace,
* thereby changing the way that command/variable names are interpreted.
* This allows extension writers to support different name resolution
* schemes, such as those for object-oriented packages.
*
* Command resolution is handled by a function of the following type:
*
* typedef int (*Tcl_ResolveCmdProc)(Tcl_Interp *interp,
* CONST char *name, Tcl_Namespace *context,
* int flags, Tcl_Command *rPtr);
*
* Whenever a command is executed or Tcl_FindCommand is invoked within
* the namespace, this function is called to resolve the command name. If
* this function is able to resolve the name, it should return the status
* code TCL_OK, along with the corresponding Tcl_Command in the rPtr
* argument. Otherwise, the function can return TCL_CONTINUE, and the
* command will be treated under the usual name resolution rules. Or, it
* can return TCL_ERROR, and the command will be considered invalid.
*
* Variable resolution is handled by two functions. The first is called
* whenever a variable needs to be resolved at compile time:
*
* typedef int (*Tcl_ResolveCompiledVarProc)(Tcl_Interp *interp,
* CONST char *name, Tcl_Namespace *context,
* Tcl_ResolvedVarInfo *rPtr);
*
* If this function is able to resolve the name, it should return the
* status code TCL_OK, along with variable resolution info in the rPtr
* argument; this info will be used to set up compiled locals in the call
* frame at runtime. The function may also return TCL_CONTINUE, and the
* variable will be treated under the usual name resolution rules. Or, it
* can return TCL_ERROR, and the variable will be considered invalid.
*
* Another function is used whenever a variable needs to be resolved at
* runtime but it is not recognized as a compiled local. (For example,
* the variable may be requested via Tcl_FindNamespaceVar.) This function
* has the following type:
*
* typedef int (*Tcl_ResolveVarProc)(Tcl_Interp *interp,
* CONST char *name, Tcl_Namespace *context,
* int flags, Tcl_Var *rPtr);
*
* This function is quite similar to the compile-time version. It returns
* the same status codes, but if variable resolution succeeds, this
* function returns a Tcl_Var directly via the rPtr argument.
*
* Results:
* Nothing.
*
* Side effects:
* Bumps the command epoch counter for the namespace, invalidating all
* command references in that namespace. Also bumps the resolver epoch
* counter for the namespace, forcing all code in the namespace to be
* recompiled.
*
*----------------------------------------------------------------------
*/
void
Tcl_SetNamespaceResolvers(
Tcl_Namespace *namespacePtr,/* Namespace whose resolution rules are being
* modified. */
Tcl_ResolveCmdProc *cmdProc,/* Function for command resolution */
Tcl_ResolveVarProc *varProc,/* Function for variable resolution at
* run-time */
Tcl_ResolveCompiledVarProc *compiledVarProc)
/* Function for variable resolution at compile
* time. */
{
Namespace *nsPtr = (Namespace *) namespacePtr;
/*
* Plug in the new command resolver, and bump the epoch counters so that
* all code will have to be recompiled and all commands will have to be
* resolved again using the new policy.
*/
nsPtr->cmdResProc = cmdProc;
nsPtr->varResProc = varProc;
nsPtr->compiledVarResProc = compiledVarProc;
nsPtr->cmdRefEpoch++;
nsPtr->resolverEpoch++;
TclInvalidateNsPath(nsPtr);
}
/*
*----------------------------------------------------------------------
*
* Tcl_GetNamespaceResolvers --
*
* Returns the current command/variable resolution functions for a
* namespace. By default, these functions are NULL. New functions can be
* installed by calling Tcl_SetNamespaceResolvers, to provide new name
* resolution rules.
*
* Results:
* Returns non-zero if any name resolution functions have been assigned
* to this namespace; also returns pointers to the functions in the
* Tcl_ResolverInfo structure. Returns zero otherwise.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
int
Tcl_GetNamespaceResolvers(
Tcl_Namespace *namespacePtr,/* Namespace whose resolution rules are being
* modified. */
Tcl_ResolverInfo *resInfoPtr)
/* Returns: pointers for all name resolution
* functions assigned to this namespace. */
{
Namespace *nsPtr = (Namespace *) namespacePtr;
resInfoPtr->cmdResProc = nsPtr->cmdResProc;
resInfoPtr->varResProc = nsPtr->varResProc;
resInfoPtr->compiledVarResProc = nsPtr->compiledVarResProc;
if (nsPtr->cmdResProc != NULL || nsPtr->varResProc != NULL ||
nsPtr->compiledVarResProc != NULL) {
return 1;
}
return 0;
}
/*
* Local Variables:
* mode: c
* c-basic-offset: 4
* fill-column: 78
* End:
*/
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