/*
 * 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 1.85 2007/08/28 16:24:29 dgp Exp $
 * RCS: @(#) $Id: tclCompExpr.c,v 1.86 2007/08/28 17:43:07 dgp Exp $
 */

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

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

    INST_UMINUS,	/* UNARY_MINUS */
    0,			/* FUNCTION */
    0,			/* START */
    0,			/* OPEN_PAREN */
    INST_LNOT,		/* NOT*/
    INST_BITNOT,	/* BIT_NOT*/
};

/*
 * A table mapping a byte value to the corresponding lexeme for use by
 * ParseLexeme().
 */

static unsigned char Lexeme[] = {
	INVALID		/* NUL */,	INVALID		/* SOH */,
	INVALID		/* STX */,	INVALID		/* ETX */,
	INVALID		/* EOT */,	INVALID		/* ENQ */,
	INVALID		/* ACK */,	INVALID		/* BEL */,
	INVALID		/* BS */,	INVALID		/* HT */,
	INVALID		/* LF */,	INVALID		/* VT */,
	INVALID		/* FF */,	INVALID		/* CR */,
	INVALID		/* SO */,	INVALID		/* SI */,
	INVALID		/* DLE */,	INVALID		/* DC1 */,
	INVALID		/* DC2 */,	INVALID		/* DC3 */,
	INVALID		/* DC4 */,	INVALID		/* NAK */,
	INVALID		/* SYN */,	INVALID		/* ETB */,
	INVALID		/* CAN */,	INVALID		/* EM */,
	INVALID		/* SUB */,	INVALID		/* ESC */,
	INVALID		/* FS */,	INVALID		/* GS */,
	INVALID		/* RS */,	INVALID		/* US */,
	INVALID		/* SPACE */,	0 		/* ! or != */,
	QUOTED		/* " */,	INVALID		/* # */,
	VARIABLE	/* $ */,	MOD		/* % */,
	0		/* & or && */,	INVALID		/* ' */,
	OPEN_PAREN	/* ( */,	CLOSE_PAREN	/* ) */,
	0		/* * or ** */,	PLUS		/* + */,
	COMMA		/* , */,	MINUS		/* - */,
	0		/* . */,	DIVIDE		/* / */,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0,			/* 0-9 */
	COLON		/* : */,	INVALID		/* ; */,
	0		/* < or << or <= */,
	0		/* == or INVALID */,
	0		/* > or >> or >= */,
	QUESTION	/* ? */,	INVALID		/* @ */,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,		/* A-M */
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,		/* N-Z */
	SCRIPT		/* [ */,	INVALID		/* \ */,
	INVALID		/* ] */,	BIT_XOR		/* ^ */,
	INVALID		/* _ */,	INVALID		/* ` */,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,		/* a-m */
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,		/* n-z */
	BRACED		/* { */,	0		/* | or || */,
	INVALID		/* } */,	BIT_NOT		/* ~ */,
	INVALID		/* DEL */
};

/*
 * The JumpList struct is used to create a stack of data needed for the
 * TclEmitForwardJump() and TclFixupForwardJump() calls that are performed
 * when compiling the short-circuiting operators QUESTION/COLON, AND, and OR.
 * Keeping a stack permits the CompileExprTree() routine to be non-recursive.
 */

    Tcl_Obj **literalPtr)	/* Write corresponding literal value to this
				   storage, if non-NULL. */
{
    const char *end;
    int scanned;
    Tcl_UniChar ch;
    Tcl_Obj *literal = NULL;

    unsigned char byte;
/* TODO: Consider table lookup */

    if (numBytes == 0) {
	*lexemePtr = END;
	return 0;
    }
    switch (*start) {
    case '[':
	*lexemePtr = SCRIPT;
	return 1;

    byte = (unsigned char)(*start);
    case '{':
	*lexemePtr = BRACED;
	return 1;

    if (byte < sizeof(Lexeme) && Lexeme[byte] != 0) {
    case '(':
	*lexemePtr = OPEN_PAREN;
	return 1;

    case ')':
	*lexemePtr = CLOSE_PAREN;
	return 1;

    case '$':
	*lexemePtr = VARIABLE;
	return 1;

    case '\"':
	*lexemePtr = QUOTED;
	return 1;

    case ',':
	*lexemePtr = COMMA;
	return 1;

    case '/':
	*lexemePtr = DIVIDE;
	return 1;

    case '%':
	*lexemePtr = MOD;
	*lexemePtr = Lexeme[byte];
	return 1;

    }
    case '+':
	*lexemePtr = PLUS;
	return 1;

    switch (byte) {
    case '-':
	*lexemePtr = MINUS;
	return 1;

    case '?':
	*lexemePtr = QUESTION;
	return 1;

    case ':':
	*lexemePtr = COLON;
	return 1;

    case '^':
	*lexemePtr = BIT_XOR;
	return 1;

    case '~':
	*lexemePtr = BIT_NOT;
	return 1;

    case '*':
	if ((numBytes > 1) && (start[1] == '*')) {
	    *lexemePtr = EXPON;
	    return 2;
	}
	*lexemePtr = MULT;
	return 1;