diff options
Diffstat (limited to 'generic/tclBasic.c')
| -rw-r--r-- | generic/tclBasic.c | 100 |
1 files changed, 73 insertions, 27 deletions
diff --git a/generic/tclBasic.c b/generic/tclBasic.c index 6dc8d56..619a504 100644 --- a/generic/tclBasic.c +++ b/generic/tclBasic.c @@ -814,7 +814,9 @@ Tcl_CreateInterp(void) */ Tcl_CreateObjCommand(interp, "::tcl::unsupported::disassemble", - Tcl_DisassembleObjCmd, NULL, NULL); + Tcl_DisassembleObjCmd, INT2PTR(0), NULL); + Tcl_CreateObjCommand(interp, "::tcl::unsupported::getbytecode", + Tcl_DisassembleObjCmd, INT2PTR(1), NULL); Tcl_CreateObjCommand(interp, "::tcl::unsupported::representation", Tcl_RepresentationCmd, NULL, NULL); @@ -3748,8 +3750,9 @@ TclNREvalObjv( /* * data[1] stores a marker for use by tailcalls; it will be set to 1 by - * command redirectors (imports, alias, ensembles) so that tailcalls - * finishes the source command and not just the target. + * command redirectors (imports, alias, ensembles) so that tailcall skips + * this callback (that marks the end of the target command) and goes back + * to the end of the source command. */ if (iPtr->deferredCallbacks) { @@ -3997,7 +4000,7 @@ NRCommand( iPtr->numLevels--; /* - * If there is a tailcall, schedule it + * If there is a tailcall, schedule it next */ if (data[1] && (data[1] != INT2PTR(1))) { @@ -7455,27 +7458,31 @@ Tcl_NRCmdSwap( } /***************************************************************************** - * Stuff for tailcalls + * Tailcall related code ***************************************************************************** * - * Just to show that IT CAN BE DONE! The precise semantics are not simple, - * require more thought. Possibly need a new Tcl return code to do it right? - * Questions include: - * (1) How is the objc/objv tailcall to be run? My current thinking is that - * it should essentially be - * [tailcall a b c] <=> [uplevel 1 [list a b c]] - * with two caveats - * (a) the current frame is dropped first, after running all pending - * cleanup tasks and saving its namespace - * (b) 'a' is looked up in the returning frame's namespace, but the - * command is run in the context to which we are returning - * Current implementation does this if [tailcall] is called from within - * a proc, errors otherwise. - * (2) Should a tailcall bypass [catch] in the returning frame? Current - * implementation does not (or does it? Changed, test!) - it causes an - * error. - * - * FIXME NRE! + * The steps of the tailcall dance are as follows: + * + * 1. when [tailcall] is invoked, it stores the corresponding callback in + * the current CallFrame and returns TCL_RETURN + * 2. when the CallFrame is popped, it calls TclSetTailcall to store the + * callback in the proper NRCommand callback - the spot where the command + * that pushed the CallFrame is completely cleaned up + * 3. when the NRCommand callback runs, it schedules the tailcall callback + * to run immediately after it returns + * + * One delicate point is to properly define the NRCommand where the tailcall + * will execute. There are functions whose purpose is to help define the + * precise spot: + * TclMarkTailcall: if the NEXT command to be pushed tailcalls, execution + * should continue right here + * TclSkipTailcall: if the NEXT command to be pushed tailcalls, execution + * should continue after the CURRENT command is fully returned ("skip + * the next command: we are redirecting to it, tailcalls should run + * after WE return") + * TclPushTailcallPoint: the search for a tailcalling spot cannot traverse + * this point. This is special for OO, as some of the oo constructs + * that behave like commands may not push an NRCommand callback. */ void @@ -7509,6 +7516,18 @@ TclPushTailcallPoint( ((Interp *) interp)->numLevels++; } + +/* + *---------------------------------------------------------------------- + * + * TclSetTailcall -- + * + * Splice a tailcall command in the proper spot of the NRE callback + * stack, so that it runs at the right time. + * + *---------------------------------------------------------------------- + */ + void TclSetTailcall( Tcl_Interp *interp, @@ -7533,6 +7552,23 @@ TclSetTailcall( runPtr->data[1] = listPtr; } + +/* + *---------------------------------------------------------------------- + * + * TclNRTailcallObjCmd -- + * + * Prepare the tailcall as a list and store it in the current + * varFrame. When the frame is later popped the tailcall will be spliced + * at the proper place. + * + * Results: + * The first NRCommand callback that is not marked to be skipped is + * updated so that its data[1] field contains the tailcall list. + * + *---------------------------------------------------------------------- + */ + int TclNRTailcallObjCmd( ClientData clientData, @@ -7547,9 +7583,9 @@ TclNRTailcallObjCmd( return TCL_ERROR; } - if (!(iPtr->varFramePtr->isProcCallFrame & 1)) { /* or is upleveled */ + if (!(iPtr->varFramePtr->isProcCallFrame & 1)) { Tcl_SetObjResult(interp, Tcl_NewStringObj( - "tailcall can only be called from a proc or lambda", -1)); + "tailcall can only be called from a proc, lambda or method", -1)); Tcl_SetErrorCode(interp, "TCL", "TAILCALL", "ILLEGAL", NULL); return TCL_ERROR; } @@ -7567,8 +7603,7 @@ TclNRTailcallObjCmd( /* * Create the callback to actually evaluate the tailcalled * command, then set it in the varFrame so that PopCallFrame can use it - * at the proper time. Being lazy: exploit the TclNRAddCallBack macro to - * build the callback. + * at the proper time. */ if (objc > 1) { @@ -7593,6 +7628,17 @@ TclNRTailcallObjCmd( return TCL_RETURN; } + +/* + *---------------------------------------------------------------------- + * + * TclNRTailcallEval -- + * + * This NREcallback actually causes the tailcall to be evaluated. + * + *---------------------------------------------------------------------- + */ + int TclNRTailcallEval( ClientData data[], |