/*
 * tclCompExpr.c --
 *
 *	This file contains the code to parse and compile Tcl expressions
 *	and implementations of the Tcl commands corresponding to expression
 *	operators, such as the command ::tcl::mathop::+ .
 *
 * Contributions from Don Porter, NIST, 2006-2007. (not subject to US copyright)
 *
 * See the file "license.terms" for information on usage and redistribution of
 * this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclCompExpr.c,v 1.14.2.35 2008/01/17 22:03:14 dgp Exp $
 */

#include "tclInt.h"
#include "tclCompile.h"		/* CompileEnv */

/*
 * Expression parsing takes place in the routine ParseExpr().  It takes a

		}
		goto error;
	    }

	    switch (lexeme) {
	    case NUMBER:
	    case BOOLEAN: 
		/*
		 * TODO: Consider using a dict or hash to collapse all
		 * duplicate literals into a single representative value.
		 * (Like what is done with [split $s {}]).
		 * Pro:	~75% memory saving on expressions like
		 *	{1+1+1+1+1+.....+1} (Convert "pointer + Tcl_Obj" cost
		 *	to "pointer" cost only)
		 * Con:	Cost of the dict store/retrieve on every literal
		 *	in every expression when expressions like the above
		 *	tend to be uncommon.
		 *	The memory savings is temporary; Compiling to bytecode
		 *	will collapse things as literals are registered
		 * 	anyway, so the savings applies only to the time
		 *	between parsing and compiling.  Possibly important
		 *	due to high-water mark nature of memory allocation.
		 */
		Tcl_ListObjAppendElement(NULL, litList, literal);
		complete = lastParsed = OT_LITERAL;
		start += scanned;
		numBytes -= scanned;
		continue;
	    
	    default:

	    numWords = 1;	/* No arguments, so just the command */
	    break;
	case OT_LITERAL: {
	    Tcl_Obj *const *litObjv = *litObjvPtr;
	    Tcl_Obj *literal = *litObjv;

	    if (optimize) {
		int length, index;
		const char *bytes = TclGetStringFromObj(literal, &length);
		LiteralEntry *lePtr;
		Tcl_Obj *objPtr;


		index = TclRegisterNewLiteral(envPtr, bytes, length);
		lePtr = envPtr->literalArrayPtr + index;
		objPtr = lePtr->objPtr;
		if ((objPtr->typePtr == NULL) && (literal->typePtr != NULL)) {
		    /*
		     * Would like to do this:
		     *
		     * lePtr->objPtr = literal;
		     * Tcl_IncrRefCount(literal);
		     * Tcl_DecrRefCount(objPtr);
		     *
		     * However, the design of the "global" and "local"
		     * LiteralTable does not permit the value of lePtr->objPtr
		     * to change.  So rather than replace lePtr->objPtr, we
		     * do surgery to transfer our desired intrep into it.
		     *
		     */
		    objPtr->typePtr = literal->typePtr;
		    objPtr->internalRep = literal->internalRep;
		    literal->typePtr = NULL;
		}
		TclEmitPush(index, envPtr);
	    } else {
		/*
		 * When optimize==0, we know the expression is a one-off
		 * and there's nothing to be gained from sharing literals
		 * when they won't live long, and the copies we have already
		 * have an appropriate intrep.  In this case, skip literal
		 * registration that would enable sharing, and use the routine