shared_source/tcl_base/tclparseexpr.c

/* $Header: /cvsroot/esrg/sfesrg/esrgpcpj/shared/tcl_base/tclparseexpr.c,v 1.1.1.1 2001/06/13 04:44:43 dtashley Exp $ */

/* 
 * tclParseExpr.c --
 *
 *      This file contains procedures that parse Tcl expressions. They
 *      do so in a general-purpose fashion that can be used for many
 *      different purposes, including compilation, direct execution,
 *      code analysis, etc.
 *
 * Copyright (c) 1997 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclparseexpr.c,v 1.1.1.1 2001/06/13 04:44:43 dtashley Exp $
 */

#include "tclInt.h"
#include "tclCompile.h"

/*
 * The stuff below is a bit of a hack so that this file can be used in
 * environments that include no UNIX, i.e. no errno: just arrange to use
 * the errno from tclExecute.c here.
 */

#ifndef TCL_GENERIC_ONLY
#include "tclPort.h"
#else
#define NO_ERRNO_H
#endif

#ifdef NO_ERRNO_H
extern int errno;                       /* Use errno from tclExecute.c. */
#define ERANGE 34
#endif

/*
 * Boolean variable that controls whether expression parse tracing
 * is enabled.
 */

#ifdef TCL_COMPILE_DEBUG
static int traceParseExpr = 0;
#endif /* TCL_COMPILE_DEBUG */

/*
 * The ParseInfo structure holds state while parsing an expression.
 * A pointer to an ParseInfo record is passed among the routines in
 * this module.
 */

typedef struct ParseInfo {
    Tcl_Parse *parsePtr;        /* Points to structure to fill in with
                                 * information about the expression. */
    int lexeme;                 /* Type of last lexeme scanned in expr.
                                 * See below for definitions. Corresponds to
                                 * size characters beginning at start. */
    char *start;                /* First character in lexeme. */
    int size;                   /* Number of bytes in lexeme. */
    char *next;                 /* Position of the next character to be
                                 * scanned in the expression string. */
    char *prevEnd;              /* Points to the character just after the
                                 * last one in the previous lexeme. Used to
                                 * compute size of subexpression tokens. */
    char *originalExpr;         /* Points to the start of the expression
                                 * originally passed to Tcl_ParseExpr. */
    char *lastChar;             /* Points just after last byte of expr. */
} ParseInfo;

/*
 * Definitions of the different lexemes that appear in expressions. The
 * order of these must match the corresponding entries in the
 * operatorStrings array below.
 */

#define LITERAL         0
#define FUNC_NAME       1
#define OPEN_BRACKET    2
#define OPEN_BRACE      3
#define OPEN_PAREN      4
#define CLOSE_PAREN     5
#define DOLLAR          6
#define QUOTE           7
#define COMMA           8
#define END             9
#define UNKNOWN         10

/*
 * Binary operators:
 */

#define MULT            11
#define DIVIDE          12
#define MOD             13
#define PLUS            14
#define MINUS           15
#define LEFT_SHIFT      16
#define RIGHT_SHIFT     17
#define LESS            18
#define GREATER         19
#define LEQ             20
#define GEQ             21
#define EQUAL           22
#define NEQ             23
#define BIT_AND         24
#define BIT_XOR         25
#define BIT_OR          26
#define AND             27
#define OR              28
#define QUESTY          29
#define COLON           30

/*
 * Unary operators. Unary minus and plus are represented by the (binary)
 * lexemes MINUS and PLUS.
 */

#define NOT             31
#define BIT_NOT         32

/*
 * Mapping from lexemes to strings; used for debugging messages. These
 * entries must match the order and number of the lexeme definitions above.
 */

#ifdef TCL_COMPILE_DEBUG
static char *lexemeStrings[] = {
    "LITERAL", "FUNCNAME",
    "[", "{", "(", ")", "$", "\"", ",", "END", "UNKNOWN",
    "*", "/", "%", "+", "-",
    "<<", ">>", "<", ">", "<=", ">=", "==", "!=",
    "&", "^", "|", "&&", "||", "?", ":",
    "!", "~"
};
#endif /* TCL_COMPILE_DEBUG */

/*
 * Declarations for local procedures to this file:
 */

static int              GetLexeme _ANSI_ARGS_((ParseInfo *infoPtr));
static void             LogSyntaxError _ANSI_ARGS_((ParseInfo *infoPtr));
static int              ParseAddExpr _ANSI_ARGS_((ParseInfo *infoPtr));
static int              ParseBitAndExpr _ANSI_ARGS_((ParseInfo *infoPtr));
static int              ParseBitOrExpr _ANSI_ARGS_((ParseInfo *infoPtr));
static int              ParseBitXorExpr _ANSI_ARGS_((ParseInfo *infoPtr));
static int              ParseCondExpr _ANSI_ARGS_((ParseInfo *infoPtr));
static int              ParseEqualityExpr _ANSI_ARGS_((ParseInfo *infoPtr));
static int              ParseLandExpr _ANSI_ARGS_((ParseInfo *infoPtr));
static int              ParseLorExpr _ANSI_ARGS_((ParseInfo *infoPtr));
static int              ParseMultiplyExpr _ANSI_ARGS_((ParseInfo *infoPtr));
static int              ParsePrimaryExpr _ANSI_ARGS_((ParseInfo *infoPtr));
static int              ParseRelationalExpr _ANSI_ARGS_((ParseInfo *infoPtr));
static int              ParseShiftExpr _ANSI_ARGS_((ParseInfo *infoPtr));
static int              ParseUnaryExpr _ANSI_ARGS_((ParseInfo *infoPtr));
static void             PrependSubExprTokens _ANSI_ARGS_((char *op,
                            int opBytes, char *src, int srcBytes,
                            int firstIndex, ParseInfo *infoPtr));

/*
 * Macro used to debug the execution of the recursive descent parser used
 * to parse expressions.
 */

#ifdef TCL_COMPILE_DEBUG
#define HERE(production, level) \
    if (traceParseExpr) { \
        fprintf(stderr, "%*s%s: lexeme=%s, next=\"%.20s\"\n", \
                (level), " ", (production), \
                lexemeStrings[infoPtr->lexeme], infoPtr->next); \
    }
#else
#define HERE(production, level)
#endif /* TCL_COMPILE_DEBUG */

/*
 *----------------------------------------------------------------------
 *
 * Tcl_ParseExpr --
 *
 *      Given a string, this procedure parses the first Tcl expression
 *      in the string and returns information about the structure of
 *      the expression. This procedure is the top-level interface to the
 *      the expression parsing module.
 *
 * Results:
 *      The return value is TCL_OK if the command was parsed successfully
 *      and TCL_ERROR otherwise. If an error occurs and interp isn't NULL
 *      then an error message is left in its result. On a successful return,
 *      parsePtr is filled in with information about the expression that 
 *      was parsed.
 *
 * Side effects:
 *      If there is insufficient space in parsePtr to hold all the
 *      information about the expression, then additional space is
 *      malloc-ed. If the procedure returns TCL_OK then the caller must
 *      eventually invoke Tcl_FreeParse to release any additional space
 *      that was allocated.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_ParseExpr(interp, string, numBytes, parsePtr)
    Tcl_Interp *interp;         /* Used for error reporting. */
    char *string;               /* The source string to parse. */
    int numBytes;               /* Number of bytes in string. If < 0, the
                                 * string consists of all bytes up to the
                                 * first null character. */
    Tcl_Parse *parsePtr;        /* Structure to fill with information about
                                 * the parsed expression; any previous
                                 * information in the structure is
                                 * ignored. */
{
    ParseInfo info;
    int code;
    char savedChar;

    if (numBytes < 0) {
        numBytes = (string? strlen(string) : 0);
    }
#ifdef TCL_COMPILE_DEBUG
    if (traceParseExpr) {
        fprintf(stderr, "Tcl_ParseExpr: string=\"%.*s\"\n",
                numBytes, string);
    }
#endif /* TCL_COMPILE_DEBUG */
    
    parsePtr->commentStart = NULL;
    parsePtr->commentSize = 0;
    parsePtr->commandStart = NULL;
    parsePtr->commandSize = 0;
    parsePtr->numWords = 0;
    parsePtr->tokenPtr = parsePtr->staticTokens;
    parsePtr->numTokens = 0;
    parsePtr->tokensAvailable = NUM_STATIC_TOKENS;
    parsePtr->string = string;
    parsePtr->end = (string + numBytes);
    parsePtr->interp = interp;
    parsePtr->term = string;
    parsePtr->incomplete = 0;

    /*
     * Temporarily overwrite the character just after the end of the
     * string with a 0 byte.  This acts as a sentinel and reduces the
     * number of places where we have to check for the end of the
     * input string.  The original value of the byte is restored at
     * the end of the parse.
     */

    savedChar = string[numBytes];
    string[numBytes] = 0;

    /*
     * Initialize the ParseInfo structure that holds state while parsing
     * the expression.
     */

    info.parsePtr = parsePtr;
    info.lexeme = UNKNOWN;
    info.start = NULL;
    info.size = 0;
    info.next = string;
    info.prevEnd = string;
    info.originalExpr = string;
    info.lastChar = (string + numBytes); /* just after last char of expr */

    /*
     * Get the first lexeme then parse the expression.
     */

    code = GetLexeme(&info);
    if (code != TCL_OK) {
        goto error;
    }
    code = ParseCondExpr(&info);
    if (code != TCL_OK) {
        goto error;
    }
    if (info.lexeme != END) {
        LogSyntaxError(&info);
        goto error;
    }
    string[numBytes] = (char) savedChar;
    return TCL_OK;
    
    error:
    string[numBytes] = (char) savedChar;
    if (parsePtr->tokenPtr != parsePtr->staticTokens) {
        ckfree((char *) parsePtr->tokenPtr);
    }
    return TCL_ERROR;
}

/*
 *----------------------------------------------------------------------
 *
 * ParseCondExpr --
 *
 *      This procedure parses a Tcl conditional expression:
 *      condExpr ::= lorExpr ['?' condExpr ':' condExpr]
 *
 *      Note that this is the topmost recursive-descent parsing routine used
 *      by TclParseExpr to parse expressions. This avoids an extra procedure
 *      call since such a procedure would only return the result of calling
 *      ParseCondExpr. Other recursive-descent procedures that need to parse
 *      complete expressions also call ParseCondExpr.
 *
 * Results:
 *      The return value is TCL_OK on a successful parse and TCL_ERROR
 *      on failure. If TCL_ERROR is returned, then the interpreter's result
 *      contains an error message.
 *
 * Side effects:
 *      If there is insufficient space in parsePtr to hold all the
 *      information about the subexpression, then additional space is
 *      malloc-ed.
 *
 *----------------------------------------------------------------------
 */

static int
ParseCondExpr(infoPtr)
    ParseInfo *infoPtr;         /* Holds the parse state for the
                                 * expression being parsed. */
{
    Tcl_Parse *parsePtr = infoPtr->parsePtr;
    Tcl_Token *tokenPtr, *firstTokenPtr, *condTokenPtr;
    int firstIndex, numToMove, code;
    char *srcStart;
    
    HERE("condExpr", 1);
    srcStart = infoPtr->start;
    firstIndex = parsePtr->numTokens;
    
    code = ParseLorExpr(infoPtr);
    if (code != TCL_OK) {
        return code;
    }
    
    if (infoPtr->lexeme == QUESTY) {
        /*
         * Emit two tokens: one TCL_TOKEN_SUB_EXPR token for the entire
         * conditional expression, and a TCL_TOKEN_OPERATOR token for 
         * the "?" operator. Note that these two tokens must be inserted
         * before the LOR operand tokens generated above.
         */

        if ((parsePtr->numTokens + 1) >= parsePtr->tokensAvailable) {
            TclExpandTokenArray(parsePtr);
        }
        firstTokenPtr = &parsePtr->tokenPtr[firstIndex];
        tokenPtr = (firstTokenPtr + 2);
        numToMove = (parsePtr->numTokens - firstIndex);
        memmove((VOID *) tokenPtr, (VOID *) firstTokenPtr,
                (size_t) (numToMove * sizeof(Tcl_Token)));
        parsePtr->numTokens += 2;
        
        tokenPtr = firstTokenPtr;
        tokenPtr->type = TCL_TOKEN_SUB_EXPR;
        tokenPtr->start = srcStart;
        
        tokenPtr++;
        tokenPtr->type = TCL_TOKEN_OPERATOR;
        tokenPtr->start = infoPtr->start;
        tokenPtr->size = 1;
        tokenPtr->numComponents = 0;
    
        /*
         * Skip over the '?'.
         */
        
        code = GetLexeme(infoPtr); 
        if (code != TCL_OK) {
            return code;
        }

        /*
         * Parse the "then" expression.
         */

        code = ParseCondExpr(infoPtr);
        if (code != TCL_OK) {
            return code;
        }
        if (infoPtr->lexeme != COLON) {
            LogSyntaxError(infoPtr);
            return TCL_ERROR;
        }
        code = GetLexeme(infoPtr); /* skip over the ':' */
        if (code != TCL_OK) {
            return code;
        }

        /*
         * Parse the "else" expression.
         */

        code = ParseCondExpr(infoPtr);
        if (code != TCL_OK) {
            return code;
        }

        /*
         * Now set the size-related fields in the '?' subexpression token.
         */

        condTokenPtr = &parsePtr->tokenPtr[firstIndex];
        condTokenPtr->size = (infoPtr->prevEnd - srcStart);
        condTokenPtr->numComponents = parsePtr->numTokens - (firstIndex+1);
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ParseLorExpr --
 *
 *      This procedure parses a Tcl logical or expression:
 *      lorExpr ::= landExpr {'||' landExpr}
 *
 * Results:
 *      The return value is TCL_OK on a successful parse and TCL_ERROR
 *      on failure. If TCL_ERROR is returned, then the interpreter's result
 *      contains an error message.
 *
 * Side effects:
 *      If there is insufficient space in parsePtr to hold all the
 *      information about the subexpression, then additional space is
 *      malloc-ed.
 *
 *----------------------------------------------------------------------
 */

static int
ParseLorExpr(infoPtr)
    ParseInfo *infoPtr;         /* Holds the parse state for the
                                 * expression being parsed. */
{
    Tcl_Parse *parsePtr = infoPtr->parsePtr;
    int firstIndex, code;
    char *srcStart, *operator;
    
    HERE("lorExpr", 2);
    srcStart = infoPtr->start;
    firstIndex = parsePtr->numTokens;
    
    code = ParseLandExpr(infoPtr);
    if (code != TCL_OK) {
        return code;
    }

    while (infoPtr->lexeme == OR) {
        operator = infoPtr->start;
        code = GetLexeme(infoPtr); /* skip over the '||' */
        if (code != TCL_OK) {
            return code;
        }
        code = ParseLandExpr(infoPtr);
        if (code != TCL_OK) {
            return code;
        }

        /*
         * Generate tokens for the LOR subexpression and the '||' operator.
         */

        PrependSubExprTokens(operator, 2, srcStart,
                (infoPtr->prevEnd - srcStart), firstIndex, infoPtr);
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ParseLandExpr --
 *
 *      This procedure parses a Tcl logical and expression:
 *      landExpr ::= bitOrExpr {'&&' bitOrExpr}
 *
 * Results:
 *      The return value is TCL_OK on a successful parse and TCL_ERROR
 *      on failure. If TCL_ERROR is returned, then the interpreter's result
 *      contains an error message.
 *
 * Side effects:
 *      If there is insufficient space in parsePtr to hold all the
 *      information about the subexpression, then additional space is
 *      malloc-ed.
 *
 *----------------------------------------------------------------------
 */

static int
ParseLandExpr(infoPtr)
    ParseInfo *infoPtr;         /* Holds the parse state for the
                                 * expression being parsed. */
{
    Tcl_Parse *parsePtr = infoPtr->parsePtr;
    int firstIndex, code;
    char *srcStart, *operator;

    HERE("landExpr", 3);
    srcStart = infoPtr->start;
    firstIndex = parsePtr->numTokens;
    
    code = ParseBitOrExpr(infoPtr);
    if (code != TCL_OK) {
        return code;
    }

    while (infoPtr->lexeme == AND) {
        operator = infoPtr->start;
        code = GetLexeme(infoPtr); /* skip over the '&&' */
        if (code != TCL_OK) {
            return code;
        }
        code = ParseBitOrExpr(infoPtr);
        if (code != TCL_OK) {
            return code;
        }

        /*
         * Generate tokens for the LAND subexpression and the '&&' operator.
         */

        PrependSubExprTokens(operator, 2, srcStart,
                (infoPtr->prevEnd - srcStart), firstIndex, infoPtr);
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ParseBitOrExpr --
 *
 *      This procedure parses a Tcl bitwise or expression:
 *      bitOrExpr ::= bitXorExpr {'|' bitXorExpr}
 *
 * Results:
 *      The return value is TCL_OK on a successful parse and TCL_ERROR
 *      on failure. If TCL_ERROR is returned, then the interpreter's result
 *      contains an error message.
 *
 * Side effects:
 *      If there is insufficient space in parsePtr to hold all the
 *      information about the subexpression, then additional space is
 *      malloc-ed.
 *
 *----------------------------------------------------------------------
 */

static int
ParseBitOrExpr(infoPtr)
    ParseInfo *infoPtr;         /* Holds the parse state for the
                                 * expression being parsed. */
{
    Tcl_Parse *parsePtr = infoPtr->parsePtr;
    int firstIndex, code;
    char *srcStart, *operator;

    HERE("bitOrExpr", 4);
    srcStart = infoPtr->start;
    firstIndex = parsePtr->numTokens;
    
    code = ParseBitXorExpr(infoPtr);
    if (code != TCL_OK) {
        return code;
    }
    
    while (infoPtr->lexeme == BIT_OR) {
        operator = infoPtr->start;
        code = GetLexeme(infoPtr); /* skip over the '|' */
        if (code != TCL_OK) {
            return code;
        }

        code = ParseBitXorExpr(infoPtr);
        if (code != TCL_OK) {
            return code;
        }
        
        /*
         * Generate tokens for the BITOR subexpression and the '|' operator.
         */

        PrependSubExprTokens(operator, 1, srcStart,
                (infoPtr->prevEnd - srcStart), firstIndex, infoPtr);
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ParseBitXorExpr --
 *
 *      This procedure parses a Tcl bitwise exclusive or expression:
 *      bitXorExpr ::= bitAndExpr {'^' bitAndExpr}
 *
 * Results:
 *      The return value is TCL_OK on a successful parse and TCL_ERROR
 *      on failure. If TCL_ERROR is returned, then the interpreter's result
 *      contains an error message.
 *
 * Side effects:
 *      If there is insufficient space in parsePtr to hold all the
 *      information about the subexpression, then additional space is
 *      malloc-ed.
 *
 *----------------------------------------------------------------------
 */

static int
ParseBitXorExpr(infoPtr)
    ParseInfo *infoPtr;         /* Holds the parse state for the
                                 * expression being parsed. */
{
    Tcl_Parse *parsePtr = infoPtr->parsePtr;
    int firstIndex, code;
    char *srcStart, *operator;

    HERE("bitXorExpr", 5);
    srcStart = infoPtr->start;
    firstIndex = parsePtr->numTokens;
    
    code = ParseBitAndExpr(infoPtr);
    if (code != TCL_OK) {
        return code;
    }
    
    while (infoPtr->lexeme == BIT_XOR) {
        operator = infoPtr->start;
        code = GetLexeme(infoPtr); /* skip over the '^' */
        if (code != TCL_OK) {
            return code;
        }

        code = ParseBitAndExpr(infoPtr);
        if (code != TCL_OK) {
            return code;
        }
        
        /*
         * Generate tokens for the XOR subexpression and the '^' operator.
         */

        PrependSubExprTokens(operator, 1, srcStart,
                (infoPtr->prevEnd - srcStart), firstIndex, infoPtr);
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ParseBitAndExpr --
 *
 *      This procedure parses a Tcl bitwise and expression:
 *      bitAndExpr ::= equalityExpr {'&' equalityExpr}
 *
 * Results:
 *      The return value is TCL_OK on a successful parse and TCL_ERROR
 *      on failure. If TCL_ERROR is returned, then the interpreter's result
 *      contains an error message.
 *
 * Side effects:
 *      If there is insufficient space in parsePtr to hold all the
 *      information about the subexpression, then additional space is
 *      malloc-ed.
 *
 *----------------------------------------------------------------------
 */

static int
ParseBitAndExpr(infoPtr)
    ParseInfo *infoPtr;         /* Holds the parse state for the
                                 * expression being parsed. */
{
    Tcl_Parse *parsePtr = infoPtr->parsePtr;
    int firstIndex, code;
    char *srcStart, *operator;

    HERE("bitAndExpr", 6);
    srcStart = infoPtr->start;
    firstIndex = parsePtr->numTokens;
    
    code = ParseEqualityExpr(infoPtr);
    if (code != TCL_OK) {
        return code;
    }
    
    while (infoPtr->lexeme == BIT_AND) {
        operator = infoPtr->start;
        code = GetLexeme(infoPtr); /* skip over the '&' */
        if (code != TCL_OK) {
            return code;
        }
        code = ParseEqualityExpr(infoPtr);
        if (code != TCL_OK) {
            return code;
        }
        
        /*
         * Generate tokens for the BITAND subexpression and '&' operator.
         */

        PrependSubExprTokens(operator, 1, srcStart,
                (infoPtr->prevEnd - srcStart), firstIndex, infoPtr);
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ParseEqualityExpr --
 *
 *      This procedure parses a Tcl equality (inequality) expression:
 *      equalityExpr ::= relationalExpr {('==' | '!=') relationalExpr}
 *
 * Results:
 *      The return value is TCL_OK on a successful parse and TCL_ERROR
 *      on failure. If TCL_ERROR is returned, then the interpreter's result
 *      contains an error message.
 *
 * Side effects:
 *      If there is insufficient space in parsePtr to hold all the
 *      information about the subexpression, then additional space is
 *      malloc-ed.
 *
 *----------------------------------------------------------------------
 */

static int
ParseEqualityExpr(infoPtr)
    ParseInfo *infoPtr;         /* Holds the parse state for the
                                 * expression being parsed. */
{
    Tcl_Parse *parsePtr = infoPtr->parsePtr;
    int firstIndex, lexeme, code;
    char *srcStart, *operator;

    HERE("equalityExpr", 7);
    srcStart = infoPtr->start;
    firstIndex = parsePtr->numTokens;
    
    code = ParseRelationalExpr(infoPtr);
    if (code != TCL_OK) {
        return code;
    }

    lexeme = infoPtr->lexeme;
    while ((lexeme == EQUAL) || (lexeme == NEQ)) {
        operator = infoPtr->start;
        code = GetLexeme(infoPtr); /* skip over == or != */
        if (code != TCL_OK) {
            return code;
        }
        code = ParseRelationalExpr(infoPtr);
        if (code != TCL_OK) {
            return code;
        }

        /*
         * Generate tokens for the subexpression and '==' or '!=' operator.
         */

        PrependSubExprTokens(operator, 2, srcStart,
                (infoPtr->prevEnd - srcStart), firstIndex, infoPtr);
        lexeme = infoPtr->lexeme;
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ParseRelationalExpr --
 *
 *      This procedure parses a Tcl relational expression:
 *      relationalExpr ::= shiftExpr {('<' | '>' | '<=' | '>=') shiftExpr}
 *
 * Results:
 *      The return value is TCL_OK on a successful parse and TCL_ERROR
 *      on failure. If TCL_ERROR is returned, then the interpreter's result
 *      contains an error message.
 *
 * Side effects:
 *      If there is insufficient space in parsePtr to hold all the
 *      information about the subexpression, then additional space is
 *      malloc-ed.
 *
 *----------------------------------------------------------------------
 */

static int
ParseRelationalExpr(infoPtr)
    ParseInfo *infoPtr;         /* Holds the parse state for the
                                 * expression being parsed. */
{
    Tcl_Parse *parsePtr = infoPtr->parsePtr;
    int firstIndex, lexeme, operatorSize, code;
    char *srcStart, *operator;

    HERE("relationalExpr", 8);
    srcStart = infoPtr->start;
    firstIndex = parsePtr->numTokens;
    
    code = ParseShiftExpr(infoPtr);
    if (code != TCL_OK) {
        return code;
    }

    lexeme = infoPtr->lexeme;
    while ((lexeme == LESS) || (lexeme == GREATER) || (lexeme == LEQ)
            || (lexeme == GEQ)) {
        operator = infoPtr->start;
        if ((lexeme == LEQ) || (lexeme == GEQ)) {
            operatorSize = 2;
        } else {
            operatorSize = 1;
        }
        code = GetLexeme(infoPtr); /* skip over the operator */
        if (code != TCL_OK) {
            return code;
        }
        code = ParseShiftExpr(infoPtr);
        if (code != TCL_OK) {
            return code;
        }

        /*
         * Generate tokens for the subexpression and the operator.
         */

        PrependSubExprTokens(operator, operatorSize, srcStart,
                (infoPtr->prevEnd - srcStart), firstIndex, infoPtr);
        lexeme = infoPtr->lexeme;
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ParseShiftExpr --
 *
 *      This procedure parses a Tcl shift expression:
 *      shiftExpr ::= addExpr {('<<' | '>>') addExpr}
 *
 * Results:
 *      The return value is TCL_OK on a successful parse and TCL_ERROR
 *      on failure. If TCL_ERROR is returned, then the interpreter's result
 *      contains an error message.
 *
 * Side effects:
 *      If there is insufficient space in parsePtr to hold all the
 *      information about the subexpression, then additional space is
 *      malloc-ed.
 *
 *----------------------------------------------------------------------
 */

static int
ParseShiftExpr(infoPtr)
    ParseInfo *infoPtr;         /* Holds the parse state for the
                                 * expression being parsed. */
{
    Tcl_Parse *parsePtr = infoPtr->parsePtr;
    int firstIndex, lexeme, code;
    char *srcStart, *operator;

    HERE("shiftExpr", 9);
    srcStart = infoPtr->start;
    firstIndex = parsePtr->numTokens;
    
    code = ParseAddExpr(infoPtr);
    if (code != TCL_OK) {
        return code;
    }

    lexeme = infoPtr->lexeme;
    while ((lexeme == LEFT_SHIFT) || (lexeme == RIGHT_SHIFT)) {
        operator = infoPtr->start;
        code = GetLexeme(infoPtr); /* skip over << or >> */
        if (code != TCL_OK) {
            return code;
        }
        code = ParseAddExpr(infoPtr);
        if (code != TCL_OK) {
            return code;
        }

        /*
         * Generate tokens for the subexpression and '<<' or '>>' operator.
         */

        PrependSubExprTokens(operator, 2, srcStart,
                (infoPtr->prevEnd - srcStart), firstIndex, infoPtr);
        lexeme = infoPtr->lexeme;
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ParseAddExpr --
 *
 *      This procedure parses a Tcl addition expression:
 *      addExpr ::= multiplyExpr {('+' | '-') multiplyExpr}
 *
 * Results:
 *      The return value is TCL_OK on a successful parse and TCL_ERROR
 *      on failure. If TCL_ERROR is returned, then the interpreter's result
 *      contains an error message.
 *
 * Side effects:
 *      If there is insufficient space in parsePtr to hold all the
 *      information about the subexpression, then additional space is
 *      malloc-ed.
 *
 *----------------------------------------------------------------------
 */

static int
ParseAddExpr(infoPtr)
    ParseInfo *infoPtr;         /* Holds the parse state for the
                                 * expression being parsed. */
{
    Tcl_Parse *parsePtr = infoPtr->parsePtr;
    int firstIndex, lexeme, code;
    char *srcStart, *operator;

    HERE("addExpr", 10);
    srcStart = infoPtr->start;
    firstIndex = parsePtr->numTokens;
    
    code = ParseMultiplyExpr(infoPtr);
    if (code != TCL_OK) {
        return code;
    }

    lexeme = infoPtr->lexeme;
    while ((lexeme == PLUS) || (lexeme == MINUS)) {
        operator = infoPtr->start;
        code = GetLexeme(infoPtr); /* skip over + or - */
        if (code != TCL_OK) {
            return code;
        }
        code = ParseMultiplyExpr(infoPtr);
        if (code != TCL_OK) {
            return code;
        }

        /*
         * Generate tokens for the subexpression and '+' or '-' operator.
         */

        PrependSubExprTokens(operator, 1, srcStart,
                (infoPtr->prevEnd - srcStart), firstIndex, infoPtr);
        lexeme = infoPtr->lexeme;
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ParseMultiplyExpr --
 *
 *      This procedure parses a Tcl multiply expression:
 *      multiplyExpr ::= unaryExpr {('*' | '/' | '%') unaryExpr}
 *
 * Results:
 *      The return value is TCL_OK on a successful parse and TCL_ERROR
 *      on failure. If TCL_ERROR is returned, then the interpreter's result
 *      contains an error message.
 *
 * Side effects:
 *      If there is insufficient space in parsePtr to hold all the
 *      information about the subexpression, then additional space is
 *      malloc-ed.
 *
 *----------------------------------------------------------------------
 */

static int
ParseMultiplyExpr(infoPtr)
    ParseInfo *infoPtr;         /* Holds the parse state for the
                                 * expression being parsed. */
{
    Tcl_Parse *parsePtr = infoPtr->parsePtr;
    int firstIndex, lexeme, code;
    char *srcStart, *operator;

    HERE("multiplyExpr", 11);
    srcStart = infoPtr->start;
    firstIndex = parsePtr->numTokens;
    
    code = ParseUnaryExpr(infoPtr);
    if (code != TCL_OK) {
        return code;
    }

    lexeme = infoPtr->lexeme;
    while ((lexeme == MULT) || (lexeme == DIVIDE) || (lexeme == MOD)) {
        operator = infoPtr->start;
        code = GetLexeme(infoPtr); /* skip over * or / or % */
        if (code != TCL_OK) {
            return code;
        }
        code = ParseUnaryExpr(infoPtr);
        if (code != TCL_OK) {
            return code;
        }

        /*
         * Generate tokens for the subexpression and * or / or % operator.
         */

        PrependSubExprTokens(operator, 1, srcStart,
                (infoPtr->prevEnd - srcStart), firstIndex, infoPtr);
        lexeme = infoPtr->lexeme;
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ParseUnaryExpr --
 *
 *      This procedure parses a Tcl unary expression:
 *      unaryExpr ::= ('+' | '-' | '~' | '!') unaryExpr | primaryExpr
 *
 * Results:
 *      The return value is TCL_OK on a successful parse and TCL_ERROR
 *      on failure. If TCL_ERROR is returned, then the interpreter's result
 *      contains an error message.
 *
 * Side effects:
 *      If there is insufficient space in parsePtr to hold all the
 *      information about the subexpression, then additional space is
 *      malloc-ed.
 *
 *----------------------------------------------------------------------
 */

static int
ParseUnaryExpr(infoPtr)
    ParseInfo *infoPtr;         /* Holds the parse state for the
                                 * expression being parsed. */
{
    Tcl_Parse *parsePtr = infoPtr->parsePtr;
    int firstIndex, lexeme, code;
    char *srcStart, *operator;

    HERE("unaryExpr", 12);
    srcStart = infoPtr->start;
    firstIndex = parsePtr->numTokens;
    
    lexeme = infoPtr->lexeme;
    if ((lexeme == PLUS) || (lexeme == MINUS) || (lexeme == BIT_NOT)
            || (lexeme == NOT)) {
        operator = infoPtr->start;
        code = GetLexeme(infoPtr); /* skip over the unary operator */
        if (code != TCL_OK) {
            return code;
        }
        code = ParseUnaryExpr(infoPtr);
        if (code != TCL_OK) {
            return code;
        }

        /*
         * Generate tokens for the subexpression and the operator.
         */

        PrependSubExprTokens(operator, 1, srcStart,
                (infoPtr->prevEnd - srcStart), firstIndex, infoPtr);
    } else {                    /* must be a primaryExpr */
        code = ParsePrimaryExpr(infoPtr);
        if (code != TCL_OK) {
            return code;
        }
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ParsePrimaryExpr --
 *
 *      This procedure parses a Tcl primary expression:
 *      primaryExpr ::= literal | varReference | quotedString |
 *                      '[' command ']' | mathFuncCall | '(' condExpr ')'
 *
 * Results:
 *      The return value is TCL_OK on a successful parse and TCL_ERROR
 *      on failure. If TCL_ERROR is returned, then the interpreter's result
 *      contains an error message.
 *
 * Side effects:
 *      If there is insufficient space in parsePtr to hold all the
 *      information about the subexpression, then additional space is
 *      malloc-ed.
 *
 *----------------------------------------------------------------------
 */

static int
ParsePrimaryExpr(infoPtr)
    ParseInfo *infoPtr;         /* Holds the parse state for the
                                 * expression being parsed. */
{
    Tcl_Parse *parsePtr = infoPtr->parsePtr;
    Tcl_Interp *interp = parsePtr->interp;
    Tcl_Token *tokenPtr, *exprTokenPtr;
    Tcl_Parse nested;
    char *dollarPtr, *stringStart, *termPtr, *src;
    int lexeme, exprIndex, firstIndex, numToMove, code;

    /*
     * We simply recurse on parenthesized subexpressions.
     */

    HERE("primaryExpr", 13);
    lexeme = infoPtr->lexeme;
    if (lexeme == OPEN_PAREN) {
        code = GetLexeme(infoPtr); /* skip over the '(' */
        if (code != TCL_OK) {
            return code;
        }
        code = ParseCondExpr(infoPtr);
        if (code != TCL_OK) {
            return code;
        }
        if (infoPtr->lexeme != CLOSE_PAREN) {
            goto syntaxError;
        }
        code = GetLexeme(infoPtr); /* skip over the ')' */
        if (code != TCL_OK) {
            return code;
        }
        return TCL_OK;
    }

    /*
     * Start a TCL_TOKEN_SUB_EXPR token for the primary.
     */

    if (parsePtr->numTokens == parsePtr->tokensAvailable) {
        TclExpandTokenArray(parsePtr);
    }
    exprIndex = parsePtr->numTokens;
    exprTokenPtr = &parsePtr->tokenPtr[exprIndex];
    exprTokenPtr->type = TCL_TOKEN_SUB_EXPR;
    exprTokenPtr->start = infoPtr->start;
    parsePtr->numTokens++;

    /*
     * Process the primary then finish setting the fields of the
     * TCL_TOKEN_SUB_EXPR token. Note that we can't use the pointer now
     * stored in "exprTokenPtr" in the code below since the token array
     * might be reallocated.
     */

    firstIndex = parsePtr->numTokens;
    switch (lexeme) {
    case LITERAL:
        /*
         * Int or double number.
         */
        
        if (parsePtr->numTokens == parsePtr->tokensAvailable) {
            TclExpandTokenArray(parsePtr);
        }
        tokenPtr = &parsePtr->tokenPtr[parsePtr->numTokens];
        tokenPtr->type = TCL_TOKEN_TEXT;
        tokenPtr->start = infoPtr->start;
        tokenPtr->size = infoPtr->size;
        tokenPtr->numComponents = 0;
        parsePtr->numTokens++;

        exprTokenPtr = &parsePtr->tokenPtr[exprIndex];
        exprTokenPtr->size = infoPtr->size;
        exprTokenPtr->numComponents = 1;
        break;
        
    case DOLLAR:
        /*
         * $var variable reference.
         */
        
        dollarPtr = (infoPtr->next - 1);
        code = Tcl_ParseVarName(interp, dollarPtr,
                (infoPtr->lastChar - dollarPtr), parsePtr, 1);
        if (code != TCL_OK) {
            return code;
        }
        infoPtr->next = dollarPtr + parsePtr->tokenPtr[firstIndex].size;

        exprTokenPtr = &parsePtr->tokenPtr[exprIndex];
        exprTokenPtr->size = parsePtr->tokenPtr[firstIndex].size;
        exprTokenPtr->numComponents =
                (parsePtr->tokenPtr[firstIndex].numComponents + 1);
        break;
        
    case QUOTE:
        /*
         * '"' string '"'
         */
        
        stringStart = infoPtr->next;
        code = Tcl_ParseQuotedString(interp, infoPtr->start,
                (infoPtr->lastChar - stringStart), parsePtr, 1, &termPtr);
        if (code != TCL_OK) {
            return code;
        }
        infoPtr->next = termPtr;

        exprTokenPtr = &parsePtr->tokenPtr[exprIndex];
        exprTokenPtr->size = (termPtr - exprTokenPtr->start);
        exprTokenPtr->numComponents = parsePtr->numTokens - firstIndex;

        /*
         * If parsing the quoted string resulted in more than one token,
         * insert a TCL_TOKEN_WORD token before them. This indicates that
         * the quoted string represents a concatenation of multiple tokens.
         */

        if (exprTokenPtr->numComponents > 1) {
            if (parsePtr->numTokens >= parsePtr->tokensAvailable) {
                TclExpandTokenArray(parsePtr);
            }
            tokenPtr = &parsePtr->tokenPtr[firstIndex];
            numToMove = (parsePtr->numTokens - firstIndex);
            memmove((VOID *) (tokenPtr + 1), (VOID *) tokenPtr,
                    (size_t) (numToMove * sizeof(Tcl_Token)));
            parsePtr->numTokens++;

            exprTokenPtr = &parsePtr->tokenPtr[exprIndex];
            exprTokenPtr->numComponents++;

            tokenPtr->type = TCL_TOKEN_WORD;
            tokenPtr->start = exprTokenPtr->start;
            tokenPtr->size = exprTokenPtr->size;
            tokenPtr->numComponents = (exprTokenPtr->numComponents - 1);
        }
        break;
        
    case OPEN_BRACKET:
        /*
         * '[' command {command} ']'
         */

        if (parsePtr->numTokens == parsePtr->tokensAvailable) {
            TclExpandTokenArray(parsePtr);
        }
        tokenPtr = &parsePtr->tokenPtr[parsePtr->numTokens];
        tokenPtr->type = TCL_TOKEN_COMMAND;
        tokenPtr->start = infoPtr->start;
        tokenPtr->numComponents = 0;
        parsePtr->numTokens++;

        /*
         * Call Tcl_ParseCommand repeatedly to parse the nested command(s)
         * to find their end, then throw away that parse information.
         */
        
        src = infoPtr->next;
        while (1) {
            if (Tcl_ParseCommand(interp, src, (parsePtr->end - src), 1,
                    &nested) != TCL_OK) {
                parsePtr->term = nested.term;
                parsePtr->errorType = nested.errorType;
                parsePtr->incomplete = nested.incomplete;
                return TCL_ERROR;
            }
            src = (nested.commandStart + nested.commandSize);
            if (nested.tokenPtr != nested.staticTokens) {
                ckfree((char *) nested.tokenPtr);
            }
            if ((src[-1] == ']') && !nested.incomplete) {
                break;
            }
            if (src == parsePtr->end) {
                if (parsePtr->interp != NULL) {
                    Tcl_SetResult(interp, "missing close-bracket",
                            TCL_STATIC);
                }
                parsePtr->term = tokenPtr->start;
                parsePtr->errorType = TCL_PARSE_MISSING_BRACKET;
                parsePtr->incomplete = 1;
                return TCL_ERROR;
            }
        }
        tokenPtr->size = (src - tokenPtr->start);
        infoPtr->next = src;

        exprTokenPtr = &parsePtr->tokenPtr[exprIndex];
        exprTokenPtr->size = (src - tokenPtr->start);
        exprTokenPtr->numComponents = 1;
        break;

    case OPEN_BRACE:
        /*
         * '{' string '}'
         */

        code = Tcl_ParseBraces(interp, infoPtr->start,
                (infoPtr->lastChar - infoPtr->start), parsePtr, 1,
                &termPtr);
        if (code != TCL_OK) {
            return code;
        }
        infoPtr->next = termPtr;

        exprTokenPtr = &parsePtr->tokenPtr[exprIndex];
        exprTokenPtr->size = (termPtr - infoPtr->start);
        exprTokenPtr->numComponents = parsePtr->numTokens - firstIndex;

        /*
         * If parsing the braced string resulted in more than one token,
         * insert a TCL_TOKEN_WORD token before them. This indicates that
         * the braced string represents a concatenation of multiple tokens.
         */

        if (exprTokenPtr->numComponents > 1) {
            if (parsePtr->numTokens >= parsePtr->tokensAvailable) {
                TclExpandTokenArray(parsePtr);
            }
            tokenPtr = &parsePtr->tokenPtr[firstIndex];
            numToMove = (parsePtr->numTokens - firstIndex);
            memmove((VOID *) (tokenPtr + 1), (VOID *) tokenPtr,
                    (size_t) (numToMove * sizeof(Tcl_Token)));
            parsePtr->numTokens++;

            exprTokenPtr = &parsePtr->tokenPtr[exprIndex];
            exprTokenPtr->numComponents++;
            
            tokenPtr->type = TCL_TOKEN_WORD;
            tokenPtr->start = exprTokenPtr->start;
            tokenPtr->size = exprTokenPtr->size;
            tokenPtr->numComponents = exprTokenPtr->numComponents-1;
        }
        break;
        
    case FUNC_NAME:
        /*
         * math_func '(' expr {',' expr} ')'
         */
        
        if (parsePtr->numTokens == parsePtr->tokensAvailable) {
            TclExpandTokenArray(parsePtr);
        }
        tokenPtr = &parsePtr->tokenPtr[parsePtr->numTokens];
        tokenPtr->type = TCL_TOKEN_OPERATOR;
        tokenPtr->start = infoPtr->start;
        tokenPtr->size = infoPtr->size;
        tokenPtr->numComponents = 0;
        parsePtr->numTokens++;
        
        code = GetLexeme(infoPtr); /* skip over function name */
        if (code != TCL_OK) {
            return code;
        }
        if (infoPtr->lexeme != OPEN_PAREN) {
            goto syntaxError;
        }
        code = GetLexeme(infoPtr); /* skip over '(' */
        if (code != TCL_OK) {
            return code;
        }

        while (infoPtr->lexeme != CLOSE_PAREN) {
            code = ParseCondExpr(infoPtr);
            if (code != TCL_OK) {
                return code;
            }
            
            if (infoPtr->lexeme == COMMA) {
                code = GetLexeme(infoPtr); /* skip over , */
                if (code != TCL_OK) {
                    return code;
                }
            } else if (infoPtr->lexeme != CLOSE_PAREN) {
                goto syntaxError;
            }
        }

        exprTokenPtr = &parsePtr->tokenPtr[exprIndex];
        exprTokenPtr->size = (infoPtr->next - exprTokenPtr->start);
        exprTokenPtr->numComponents = parsePtr->numTokens - firstIndex;
        break;
        
    default:
        goto syntaxError;
    }

    /*
     * Advance to the next lexeme before returning.
     */
    
    code = GetLexeme(infoPtr);
    if (code != TCL_OK) {
        return code;
    }
    parsePtr->term = infoPtr->next;
    return TCL_OK;

    syntaxError:
    LogSyntaxError(infoPtr);
    return TCL_ERROR;
}

/*
 *----------------------------------------------------------------------
 *
 * GetLexeme --
 *
 *      Lexical scanner for Tcl expressions: scans a single operator or
 *      other syntactic element from an expression string.
 *
 * Results:
 *      TCL_OK is returned unless an error occurred. In that case a standard
 *      Tcl error code is returned and, if infoPtr->parsePtr->interp is
 *      non-NULL, the interpreter's result is set to hold an error
 *      message. TCL_ERROR is returned if an integer overflow, or a
 *      floating-point overflow or underflow occurred while reading in a
 *      number. If the lexical analysis is successful, infoPtr->lexeme
 *      refers to the next symbol in the expression string, and
 *      infoPtr->next is advanced past the lexeme. Also, if the lexeme is a
 *      LITERAL or FUNC_NAME, then infoPtr->start is set to the first
 *      character of the lexeme; otherwise it is set NULL.
 *
 * Side effects:
 *      If there is insufficient space in parsePtr to hold all the
 *      information about the subexpression, then additional space is
 *      malloc-ed..
 *
 *----------------------------------------------------------------------
 */

static int
GetLexeme(infoPtr)
    ParseInfo *infoPtr;         /* Holds state needed to parse the expr,
                                 * including the resulting lexeme. */
{
    register char *src;         /* Points to current source char. */
    char *termPtr;              /* Points to char terminating a literal. */
    double doubleValue;         /* Value of a scanned double literal. */
    char c;
    int startsWithDigit, offset;
    Tcl_Parse *parsePtr = infoPtr->parsePtr;
    Tcl_Interp *interp = parsePtr->interp;
    Tcl_UniChar ch;

    /*
     * Record where the previous lexeme ended. Since we always read one
     * lexeme ahead during parsing, this helps us know the source length of
     * subexpression tokens.
     */

    infoPtr->prevEnd = infoPtr->next;

    /*
     * Scan over leading white space at the start of a lexeme. Note that a
     * backslash-newline is treated as a space.
     */

    src = infoPtr->next;
    c = *src;
    while (isspace(UCHAR(c)) || (c == '\\')) { /* INTL: ISO space */
        if (c == '\\') {
            if (src[1] == '\n') {
                src += 2;
            } else {
                break;  /* no longer white space */
            }
        } else {
            src++;
        }
        c = *src;
    }
    parsePtr->term = src;
    if (src >= infoPtr->lastChar) {
        infoPtr->lexeme = END;
        infoPtr->next = src;
        return TCL_OK;
    }

    /*
     * Try to parse the lexeme first as an integer or floating-point
     * number. Don't check for a number if the first character c is
     * "+" or "-". If we did, we might treat a binary operator as unary
     * by mistake, which would eventually cause a syntax error.
     */

    if ((c != '+') && (c != '-')) {
        startsWithDigit = isdigit(UCHAR(c)); /* INTL: digit */
        if (startsWithDigit && TclLooksLikeInt(src, -1)) {
            errno = 0;
            (void) strtoul(src, &termPtr, 0);
            if (errno == ERANGE) {
                if (interp != NULL) {
                    char *s = "integer value too large to represent";
                    Tcl_ResetResult(interp);
                    Tcl_AppendToObj(Tcl_GetObjResult(interp), s, -1);
                    Tcl_SetErrorCode(interp, "ARITH", "IOVERFLOW", s,
                            (char *) NULL);
                }
                parsePtr->errorType = TCL_PARSE_BAD_NUMBER;
                return TCL_ERROR;
            }
            if (termPtr != src) {
                /*
                 * src was the start of a valid integer, but was it
                 * a bad octal?  Stopping at a digit would cause that.
                 */
                if (isdigit(UCHAR(*termPtr))) { /* INTL: digit. */
                    /*
                     * We only want to report an error for the number,
                     * but we may have something like "08+1"
                     */
                    if (interp != NULL) {
                        while (isdigit(UCHAR(*(++termPtr)))) {} /* INTL: digit. */
                        Tcl_ResetResult(interp);
                        offset = termPtr - src;
                        c = src[offset];
                        src[offset] = 0;
                        Tcl_AppendResult(interp, "\"", src,
                                "\" is an invalid octal number",
                                (char *) NULL);
                        src[offset] = c;
                    }
                    parsePtr->errorType = TCL_PARSE_BAD_NUMBER;
                    return TCL_ERROR;
                }

                infoPtr->lexeme = LITERAL;
                infoPtr->start = src;
                infoPtr->size = (termPtr - src);
                infoPtr->next = termPtr;
                parsePtr->term = termPtr;
                return TCL_OK;
            }
        } else if (startsWithDigit || (c == '.')
                || (c == 'n') || (c == 'N')) {
            errno = 0;
            doubleValue = strtod(src, &termPtr);
            if (termPtr != src) {
                if (errno != 0) {
                    if (interp != NULL) {
                        TclExprFloatError(interp, doubleValue);
                    }
                    parsePtr->errorType = TCL_PARSE_BAD_NUMBER;
                    return TCL_ERROR;
                }
                
                /*
                 * src was the start of a valid double.
                 */
                
                infoPtr->lexeme = LITERAL;
                infoPtr->start = src;
                infoPtr->size = (termPtr - src);
                infoPtr->next = termPtr;
                parsePtr->term = termPtr;
                return TCL_OK;
            }
        }
    }

    /*
     * Not an integer or double literal. Initialize the lexeme's fields
     * assuming the common case of a single character lexeme.
     */

    infoPtr->start = src;
    infoPtr->size = 1;
    infoPtr->next = src+1;
    parsePtr->term = infoPtr->next;
    
    switch (*src) {
        case '[':
            infoPtr->lexeme = OPEN_BRACKET;
            return TCL_OK;

        case '{':
            infoPtr->lexeme = OPEN_BRACE;
            return TCL_OK;

        case '(':
            infoPtr->lexeme = OPEN_PAREN;
            return TCL_OK;

        case ')':
            infoPtr->lexeme = CLOSE_PAREN;
            return TCL_OK;

        case '$':
            infoPtr->lexeme = DOLLAR;
            return TCL_OK;

        case '\"':
            infoPtr->lexeme = QUOTE;
            return TCL_OK;

        case ',':
            infoPtr->lexeme = COMMA;
            return TCL_OK;

        case '*':
            infoPtr->lexeme = MULT;
            return TCL_OK;

        case '/':
            infoPtr->lexeme = DIVIDE;
            return TCL_OK;

        case '%':
            infoPtr->lexeme = MOD;
            return TCL_OK;

        case '+':
            infoPtr->lexeme = PLUS;
            return TCL_OK;

        case '-':
            infoPtr->lexeme = MINUS;
            return TCL_OK;

        case '?':
            infoPtr->lexeme = QUESTY;
            return TCL_OK;

        case ':':
            infoPtr->lexeme = COLON;
            return TCL_OK;

        case '<':
            switch (src[1]) {
                case '<':
                    infoPtr->lexeme = LEFT_SHIFT;
                    infoPtr->size = 2;
                    infoPtr->next = src+2;
                    break;
                case '=':
                    infoPtr->lexeme = LEQ;
                    infoPtr->size = 2;
                    infoPtr->next = src+2;
                    break;
                default:
                    infoPtr->lexeme = LESS;
                    break;
            }
            parsePtr->term = infoPtr->next;
            return TCL_OK;

        case '>':
            switch (src[1]) {
                case '>':
                    infoPtr->lexeme = RIGHT_SHIFT;
                    infoPtr->size = 2;
                    infoPtr->next = src+2;
                    break;
                case '=':
                    infoPtr->lexeme = GEQ;
                    infoPtr->size = 2;
                    infoPtr->next = src+2;
                    break;
                default:
                    infoPtr->lexeme = GREATER;
                    break;
            }
            parsePtr->term = infoPtr->next;
            return TCL_OK;

        case '=':
            if (src[1] == '=') {
                infoPtr->lexeme = EQUAL;
                infoPtr->size = 2;
                infoPtr->next = src+2;
            } else {
                infoPtr->lexeme = UNKNOWN;
            }
            parsePtr->term = infoPtr->next;
            return TCL_OK;

        case '!':
            if (src[1] == '=') {
                infoPtr->lexeme = NEQ;
                infoPtr->size = 2;
                infoPtr->next = src+2;
            } else {
                infoPtr->lexeme = NOT;
            }
            parsePtr->term = infoPtr->next;
            return TCL_OK;

        case '&':
            if (src[1] == '&') {
                infoPtr->lexeme = AND;
                infoPtr->size = 2;
                infoPtr->next = src+2;
            } else {
                infoPtr->lexeme = BIT_AND;
            }
            parsePtr->term = infoPtr->next;
            return TCL_OK;

        case '^':
            infoPtr->lexeme = BIT_XOR;
            return TCL_OK;

        case '|':
            if (src[1] == '|') {
                infoPtr->lexeme = OR;
                infoPtr->size = 2;
                infoPtr->next = src+2;
            } else {
                infoPtr->lexeme = BIT_OR;
            }
            parsePtr->term = infoPtr->next;
            return TCL_OK;

        case '~':
            infoPtr->lexeme = BIT_NOT;
            return TCL_OK;

        default:
            offset = Tcl_UtfToUniChar(src, &ch);
            c = UCHAR(ch);
            if (isalpha(UCHAR(c))) {    /* INTL: ISO only. */
                infoPtr->lexeme = FUNC_NAME;
                while (isalnum(UCHAR(c)) || (c == '_')) { /* INTL: ISO only. */
                    src += offset;
                    offset = Tcl_UtfToUniChar(src, &ch);
                    c = UCHAR(ch);
                }
                infoPtr->size = (src - infoPtr->start);
                infoPtr->next = src;
                parsePtr->term = infoPtr->next;
                return TCL_OK;
            }
            infoPtr->lexeme = UNKNOWN;
            return TCL_OK;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * PrependSubExprTokens --
 *
 *      This procedure is called after the operands of an subexpression have
 *      been parsed. It generates two tokens: a TCL_TOKEN_SUB_EXPR token for
 *      the subexpression, and a TCL_TOKEN_OPERATOR token for its operator.
 *      These two tokens are inserted before the operand tokens.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      If there is insufficient space in parsePtr to hold the new tokens,
 *      additional space is malloc-ed.
 *
 *----------------------------------------------------------------------
 */

static void
PrependSubExprTokens(op, opBytes, src, srcBytes, firstIndex, infoPtr)
    char *op;                   /* Points to first byte of the operator
                                 * in the source script. */
    int opBytes;                /* Number of bytes in the operator. */
    char *src;                  /* Points to first byte of the subexpression
                                 * in the source script. */
    int srcBytes;               /* Number of bytes in subexpression's
                                 * source. */
    int firstIndex;             /* Index of first token already emitted for
                                 * operator's first (or only) operand. */
    ParseInfo *infoPtr;         /* Holds the parse state for the
                                 * expression being parsed. */
{
    Tcl_Parse *parsePtr = infoPtr->parsePtr;
    Tcl_Token *tokenPtr, *firstTokenPtr;
    int numToMove;

    if ((parsePtr->numTokens + 1) >= parsePtr->tokensAvailable) {
        TclExpandTokenArray(parsePtr);
    }
    firstTokenPtr = &parsePtr->tokenPtr[firstIndex];
    tokenPtr = (firstTokenPtr + 2);
    numToMove = (parsePtr->numTokens - firstIndex);
    memmove((VOID *) tokenPtr, (VOID *) firstTokenPtr,
            (size_t) (numToMove * sizeof(Tcl_Token)));
    parsePtr->numTokens += 2;
    
    tokenPtr = firstTokenPtr;
    tokenPtr->type = TCL_TOKEN_SUB_EXPR;
    tokenPtr->start = src;
    tokenPtr->size = srcBytes;
    tokenPtr->numComponents = parsePtr->numTokens - (firstIndex + 1);
    
    tokenPtr++;
    tokenPtr->type = TCL_TOKEN_OPERATOR;
    tokenPtr->start = op;
    tokenPtr->size = opBytes;
    tokenPtr->numComponents = 0;
}

/*
 *----------------------------------------------------------------------
 *
 * LogSyntaxError --
 *
 *      This procedure is invoked after an error occurs when parsing an
 *      expression. It sets the interpreter result to an error message
 *      describing the error.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Sets the interpreter result to an error message describing the
 *      expression that was being parsed when the error occurred.
 *
 *----------------------------------------------------------------------
 */

static void
LogSyntaxError(infoPtr)
    ParseInfo *infoPtr;         /* Holds the parse state for the
                                 * expression being parsed. */
{
    int numBytes = (infoPtr->lastChar - infoPtr->originalExpr);
    char buffer[100];

    sprintf(buffer, "syntax error in expression \"%.*s\"",
            ((numBytes > 60)? 60 : numBytes), infoPtr->originalExpr);
    Tcl_AppendStringsToObj(Tcl_GetObjResult(infoPtr->parsePtr->interp),
            buffer, (char *) NULL);
    infoPtr->parsePtr->errorType = TCL_PARSE_SYNTAX;
    infoPtr->parsePtr->term = infoPtr->start;
}


/* $History: tclparseexpr.c $
 * 
 * *****************  Version 1  *****************
 * User: Dtashley     Date: 1/02/01    Time: 1:37a
 * Created in $/IjuScripter, IjuConsole/Source/Tcl Base
 * Initial check-in.
 */ 

/* End of TCLPARSEEXPR.C */