source: trunk/tcl/tclUtil.c

/* 
 * tclUtil.c --
 *
 *      This file contains utility procedures that are used by many Tcl
 *      commands.
 *
 * Copyright (c) 1987-1993 The Regents of the University of California.
 * Copyright (c) 1994-1997 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: tclUtil.c,v 1.1 2008-06-04 13:58:11 demin Exp $
 */

#include "tclInt.h"
#include "tclPort.h"

/*
 * The following variable holds the full path name of the binary
 * from which this application was executed, or NULL if it isn't
 * know.  The value of the variable is set by the procedure
 * Tcl_FindExecutable.  The storage space is dynamically allocated.
 */
 
char *tclExecutableName = NULL;

/*
 * The following values are used in the flags returned by Tcl_ScanElement
 * and used by Tcl_ConvertElement.  The value TCL_DONT_USE_BRACES is also
 * defined in tcl.h;  make sure its value doesn't overlap with any of the
 * values below.
 *
 * TCL_DONT_USE_BRACES -        1 means the string mustn't be enclosed in
 *                              braces (e.g. it contains unmatched braces,
 *                              or ends in a backslash character, or user
 *                              just doesn't want braces);  handle all
 *                              special characters by adding backslashes.
 * USE_BRACES -                 1 means the string contains a special
 *                              character that can be handled simply by
 *                              enclosing the entire argument in braces.
 * BRACES_UNMATCHED -           1 means that braces aren't properly matched
 *                              in the argument.
 */

#define USE_BRACES              2
#define BRACES_UNMATCHED        4

/*
 * The following values determine the precision used when converting
 * floating-point values to strings.  This information is linked to all
 * of the tcl_precision variables in all interpreters via the procedure
 * TclPrecTraceProc.
 *
 * NOTE: these variables are not thread-safe.
 */

static char precisionString[10] = "12";
                                /* The string value of all the tcl_precision
                                 * variables. */
static char precisionFormat[10] = "%.12g";
                                /* The format string actually used in calls
                                 * to sprintf. */


/*
 * Function prototypes for local procedures in this file:
 */

static void             SetupAppendBuffer _ANSI_ARGS_((Interp *iPtr,
                            int newSpace));


/*
 *----------------------------------------------------------------------
 *
 * TclFindElement --
 *
 *      Given a pointer into a Tcl list, locate the first (or next)
 *      element in the list.
 *
 * Results:
 *      The return value is normally TCL_OK, which means that the
 *      element was successfully located.  If TCL_ERROR is returned
 *      it means that list didn't have proper list structure;
 *      interp->result contains a more detailed error message.
 *
 *      If TCL_OK is returned, then *elementPtr will be set to point to the
 *      first element of list, and *nextPtr will be set to point to the
 *      character just after any white space following the last character
 *      that's part of the element. If this is the last argument in the
 *      list, then *nextPtr will point just after the last character in the
 *      list (i.e., at the character at list+listLength). If sizePtr is
 *      non-NULL, *sizePtr is filled in with the number of characters in the
 *      element.  If the element is in braces, then *elementPtr will point
 *      to the character after the opening brace and *sizePtr will not
 *      include either of the braces. If there isn't an element in the list,
 *      *sizePtr will be zero, and both *elementPtr and *termPtr will point
 *      just after the last character in the list. Note: this procedure does
 *      NOT collapse backslash sequences.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

int
TclFindElement(interp, list, listLength, elementPtr, nextPtr, sizePtr,
               bracePtr)
    Tcl_Interp *interp;         /* Interpreter to use for error reporting. 
                                 * If NULL, then no error message is left
                                 * after errors. */
    char *list;                 /* Points to the first byte of a string
                                 * containing a Tcl list with zero or more
                                 * elements (possibly in braces). */
    int listLength;             /* Number of bytes in the list's string. */
    char **elementPtr;          /* Where to put address of first significant
                                 * character in first element of list. */
    char **nextPtr;             /* Fill in with location of character just
                                 * after all white space following end of
                                 * argument (next arg or end of list). */
    int *sizePtr;               /* If non-zero, fill in with size of
                                 * element. */
    int *bracePtr;              /* If non-zero, fill in with non-zero/zero
                                 * to indicate that arg was/wasn't
                                 * in braces. */
{
    char *p = list;
    char *elemStart;            /* Points to first byte of first element. */
    char *limit;                /* Points just after list's last byte. */
    int openBraces = 0;         /* Brace nesting level during parse. */
    int inQuotes = 0;
    int size = 0;               /* Init. avoids compiler warning. */
    int numChars;
    char *p2;
    
    /*
     * Skim off leading white space and check for an opening brace or
     * quote. We treat embedded NULLs in the list as bytes belonging to
     * a list element. Note: use of "isascii" below and elsewhere in this
     * procedure is a temporary hack (7/27/90) because Mx uses characters
     * with the high-order bit set for some things. This should probably
     * be changed back eventually, or all of Tcl should call isascii.
     */

    limit = (list + listLength);
    while ((p < limit) && (isspace(UCHAR(*p)))) {
        p++;
    }
    if (p == limit) {           /* no element found */
        elemStart = limit;
        goto done;
    }

    if (*p == '{') {
        openBraces = 1;
        p++;
    } else if (*p == '"') {
        inQuotes = 1;
        p++;
    }
    elemStart = p;
    if (bracePtr != 0) {
        *bracePtr = openBraces;
    }

    /*
     * Find element's end (a space, close brace, or the end of the string).
     */

    while (p < limit) {
        switch (*p) {

            /*
             * Open brace: don't treat specially unless the element is in
             * braces. In this case, keep a nesting count.
             */

            case '{':
                if (openBraces != 0) {
                    openBraces++;
                }
                break;

            /*
             * Close brace: if element is in braces, keep nesting count and
             * quit when the last close brace is seen.
             */

            case '}':
                if (openBraces > 1) {
                    openBraces--;
                } else if (openBraces == 1) {
                    size = (p - elemStart);
                    p++;
                    if ((p >= limit) || isspace(UCHAR(*p))) {
                        goto done;
                    }

                    /*
                     * Garbage after the closing brace; return an error.
                     */
                    
                    if (interp != NULL) {
                        char buf[100];
                        
                        p2 = p;
                        while ((p2 < limit) && (!isspace(UCHAR(*p2)))
                                && (p2 < p+20)) {
                            p2++;
                        }
                        sprintf(buf,
                                "list element in braces followed by \"%.*s\" instead of space",
                                (int) (p2-p), p);
                        Tcl_SetResult(interp, buf, TCL_VOLATILE);
                    }
                    return TCL_ERROR;
                }
                break;

            /*
             * Backslash:  skip over everything up to the end of the
             * backslash sequence.
             */

            case '\\': {
                (void) Tcl_Backslash(p, &numChars);
                p += (numChars - 1);
                break;
            }

            /*
             * Space: ignore if element is in braces or quotes; otherwise
             * terminate element.
             */

            case ' ':
            case '\f':
            case '\n':
            case '\r':
            case '\t':
            case '\v':
                if ((openBraces == 0) && !inQuotes) {
                    size = (p - elemStart);
                    goto done;
                }
                break;

            /*
             * Double-quote: if element is in quotes then terminate it.
             */

            case '"':
                if (inQuotes) {
                    size = (p - elemStart);
                    p++;
                    if ((p >= limit) || isspace(UCHAR(*p))) {
                        goto done;
                    }

                    /*
                     * Garbage after the closing quote; return an error.
                     */
                    
                    if (interp != NULL) {
                        char buf[100];
                        
                        p2 = p;
                        while ((p2 < limit) && (!isspace(UCHAR(*p2)))
                                 && (p2 < p+20)) {
                            p2++;
                        }
                        sprintf(buf,
                                "list element in quotes followed by \"%.*s\" %s",
                                (int) (p2-p), p, "instead of space");
                        Tcl_SetResult(interp, buf, TCL_VOLATILE);
                    }
                    return TCL_ERROR;
                }
                break;
        }
        p++;
    }


    /*
     * End of list: terminate element.
     */

    if (p == limit) {
        if (openBraces != 0) {
            if (interp != NULL) {
                Tcl_SetResult(interp, "unmatched open brace in list",
                        TCL_STATIC);
            }
            return TCL_ERROR;
        } else if (inQuotes) {
            if (interp != NULL) {
                Tcl_SetResult(interp, "unmatched open quote in list",
                        TCL_STATIC);
            }
            return TCL_ERROR;
        }
        size = (p - elemStart);
    }

    done:
    while ((p < limit) && (isspace(UCHAR(*p)))) {
        p++;
    }
    *elementPtr = elemStart;
    *nextPtr = p;
    if (sizePtr != 0) {
        *sizePtr = size;
    }
    return TCL_OK;
}


/*
 *----------------------------------------------------------------------
 *
 * TclCopyAndCollapse --
 *
 *      Copy a string and eliminate any backslashes that aren't in braces.
 *
 * Results:
 *      There is no return value. Count characters get copied from src to
 *      dst. Along the way, if backslash sequences are found outside braces,
 *      the backslashes are eliminated in the copy. After scanning count
 *      chars from source, a null character is placed at the end of dst.
 *      Returns the number of characters that got copied.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

int
TclCopyAndCollapse(count, src, dst)
    int count;                  /* Number of characters to copy from src. */
    char *src;                  /* Copy from here... */
    char *dst;                  /* ... to here. */
{
    char c;
    int numRead;
    int newCount = 0;

    for (c = *src;  count > 0;  src++, c = *src, count--) {
        if (c == '\\') {
            *dst = Tcl_Backslash(src, &numRead);
            dst++;
            src += numRead-1;
            count -= numRead-1;
            newCount++;
        } else {
            *dst = c;
            dst++;
            newCount++;
        }
    }
    *dst = 0;
    return newCount;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_SplitList --
 *
 *      Splits a list up into its constituent fields.
 *
 * Results
 *      The return value is normally TCL_OK, which means that
 *      the list was successfully split up.  If TCL_ERROR is
 *      returned, it means that "list" didn't have proper list
 *      structure;  interp->result will contain a more detailed
 *      error message.
 *
 *      *argvPtr will be filled in with the address of an array
 *      whose elements point to the elements of list, in order.
 *      *argcPtr will get filled in with the number of valid elements
 *      in the array.  A single block of memory is dynamically allocated
 *      to hold both the argv array and a copy of the list (with
 *      backslashes and braces removed in the standard way).
 *      The caller must eventually free this memory by calling free()
 *      on *argvPtr.  Note:  *argvPtr and *argcPtr are only modified
 *      if the procedure returns normally.
 *
 * Side effects:
 *      Memory is allocated.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_SplitList(interp, list, argcPtr, argvPtr)
    Tcl_Interp *interp;         /* Interpreter to use for error reporting. 
                                 * If NULL, no error message is left. */
    char *list;                 /* Pointer to string with list structure. */
    int *argcPtr;               /* Pointer to location to fill in with
                                 * the number of elements in the list. */
    char ***argvPtr;            /* Pointer to place to store pointer to
                                 * array of pointers to list elements. */
{
    char **argv;
    char *p;
    int length, size, i, result, elSize, brace;
    char *element;

    /*
     * Figure out how much space to allocate.  There must be enough
     * space for both the array of pointers and also for a copy of
     * the list.  To estimate the number of pointers needed, count
     * the number of space characters in the list.
     */

    for (size = 1, p = list; *p != 0; p++) {
        if (isspace(UCHAR(*p))) {
            size++;
        }
    }
    size++;                     /* Leave space for final NULL pointer. */
    argv = (char **) ckalloc((unsigned)
            ((size * sizeof(char *)) + (p - list) + 1));
    length = strlen(list);
    for (i = 0, p = ((char *) argv) + size*sizeof(char *);
            *list != 0;  i++) {
        char *prevList = list;
        
        result = TclFindElement(interp, list, length, &element,
                                &list, &elSize, &brace);
        length -= (list - prevList);
        if (result != TCL_OK) {
            ckfree((char *) argv);
            return result;
        }
        if (*element == 0) {
            break;
        }
        if (i >= size) {
            ckfree((char *) argv);
            if (interp != NULL) {
                Tcl_SetResult(interp, "internal error in Tcl_SplitList",
                        TCL_STATIC);
            }
            return TCL_ERROR;
        }
        argv[i] = p;
        if (brace) {
            memcpy((VOID *) p, (VOID *) element, (size_t) elSize);
            p += elSize;
            *p = 0;
            p++;
        } else {
            TclCopyAndCollapse(elSize, element, p);
            p += elSize+1;
        }
    }

    argv[i] = NULL;
    *argvPtr = argv;
    *argcPtr = i;
    return TCL_OK;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_ScanElement --
 *
 *      This procedure is a companion procedure to Tcl_ConvertElement.
 *      It scans a string to see what needs to be done to it (e.g. add
 *      backslashes or enclosing braces) to make the string into a
 *      valid Tcl list element.
 *
 * Results:
 *      The return value is an overestimate of the number of characters
 *      that will be needed by Tcl_ConvertElement to produce a valid
 *      list element from string.  The word at *flagPtr is filled in
 *      with a value needed by Tcl_ConvertElement when doing the actual
 *      conversion.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_ScanElement(string, flagPtr)
    CONST char *string;         /* String to convert to Tcl list element. */
    int *flagPtr;               /* Where to store information to guide
                                 * Tcl_ConvertCountedElement. */
{
    return Tcl_ScanCountedElement(string, -1, flagPtr);
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_ScanCountedElement --
 *
 *      This procedure is a companion procedure to
 *      Tcl_ConvertCountedElement.  It scans a string to see what
 *      needs to be done to it (e.g. add backslashes or enclosing
 *      braces) to make the string into a valid Tcl list element.
 *      If length is -1, then the string is scanned up to the first
 *      null byte.
 *
 * Results:
 *      The return value is an overestimate of the number of characters
 *      that will be needed by Tcl_ConvertCountedElement to produce a
 *      valid list element from string.  The word at *flagPtr is
 *      filled in with a value needed by Tcl_ConvertCountedElement
 *      when doing the actual conversion.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_ScanCountedElement(string, length, flagPtr)
    CONST char *string;         /* String to convert to Tcl list element. */
    int length;                 /* Number of bytes in string, or -1. */
    int *flagPtr;               /* Where to store information to guide
                                 * Tcl_ConvertElement. */
{
    int flags, nestingLevel;
    CONST char *p, *lastChar;

    /*
     * This procedure and Tcl_ConvertElement together do two things:
     *
     * 1. They produce a proper list, one that will yield back the
     * argument strings when evaluated or when disassembled with
     * Tcl_SplitList.  This is the most important thing.
     * 
     * 2. They try to produce legible output, which means minimizing the
     * use of backslashes (using braces instead).  However, there are
     * some situations where backslashes must be used (e.g. an element
     * like "{abc": the leading brace will have to be backslashed.
     * For each element, one of three things must be done:
     *
     * (a) Use the element as-is (it doesn't contain any special
     * characters).  This is the most desirable option.
     *
     * (b) Enclose the element in braces, but leave the contents alone.
     * This happens if the element contains embedded space, or if it
     * contains characters with special interpretation ($, [, ;, or \),
     * or if it starts with a brace or double-quote, or if there are
     * no characters in the element.
     *
     * (c) Don't enclose the element in braces, but add backslashes to
     * prevent special interpretation of special characters.  This is a
     * last resort used when the argument would normally fall under case
     * (b) but contains unmatched braces.  It also occurs if the last
     * character of the argument is a backslash or if the element contains
     * a backslash followed by newline.
     *
     * The procedure figures out how many bytes will be needed to store
     * the result (actually, it overestimates). It also collects information
     * about the element in the form of a flags word.
     *
     * Note: list elements produced by this procedure and
     * Tcl_ConvertCountedElement must have the property that they can be
     * enclosing in curly braces to make sub-lists.  This means, for
     * example, that we must not leave unmatched curly braces in the
     * resulting list element.  This property is necessary in order for
     * procedures like Tcl_DStringStartSublist to work.
     */

    nestingLevel = 0;
    flags = 0;
    if (string == NULL) {
        string = "";
    }
    if (length == -1) {
        length = strlen(string);
    }
    lastChar = string + length;
    p = string;
    if ((p == lastChar) || (*p == '{') || (*p == '"')) {
        flags |= USE_BRACES;
    }
    for ( ; p != lastChar; p++) {
        switch (*p) {
            case '{':
                nestingLevel++;
                break;
            case '}':
                nestingLevel--;
                if (nestingLevel < 0) {
                    flags |= TCL_DONT_USE_BRACES|BRACES_UNMATCHED;
                }
                break;
            case '[':
            case '$':
            case ';':
            case ' ':
            case '\f':
            case '\n':
            case '\r':
            case '\t':
            case '\v':
                flags |= USE_BRACES;
                break;
            case '\\':
                if ((p+1 == lastChar) || (p[1] == '\n')) {
                    flags = TCL_DONT_USE_BRACES | BRACES_UNMATCHED;
                } else {
                    int size;

                    (void) Tcl_Backslash(p, &size);
                    p += size-1;
                    flags |= USE_BRACES;
                }
                break;
        }
    }
    if (nestingLevel != 0) {
        flags = TCL_DONT_USE_BRACES | BRACES_UNMATCHED;
    }
    *flagPtr = flags;

    /*
     * Allow enough space to backslash every character plus leave
     * two spaces for braces.
     */

    return 2*(p-string) + 2;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_ConvertElement --
 *
 *      This is a companion procedure to Tcl_ScanElement.  Given
 *      the information produced by Tcl_ScanElement, this procedure
 *      converts a string to a list element equal to that string.
 *
 * Results:
 *      Information is copied to *dst in the form of a list element
 *      identical to src (i.e. if Tcl_SplitList is applied to dst it
 *      will produce a string identical to src).  The return value is
 *      a count of the number of characters copied (not including the
 *      terminating NULL character).
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_ConvertElement(src, dst, flags)
    CONST char *src;            /* Source information for list element. */
    char *dst;                  /* Place to put list-ified element. */
    int flags;                  /* Flags produced by Tcl_ScanElement. */
{
    return Tcl_ConvertCountedElement(src, -1, dst, flags);
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_ConvertCountedElement --
 *
 *      This is a companion procedure to Tcl_ScanCountedElement.  Given
 *      the information produced by Tcl_ScanCountedElement, this
 *      procedure converts a string to a list element equal to that
 *      string.
 *
 * Results:
 *      Information is copied to *dst in the form of a list element
 *      identical to src (i.e. if Tcl_SplitList is applied to dst it
 *      will produce a string identical to src).  The return value is
 *      a count of the number of characters copied (not including the
 *      terminating NULL character).
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_ConvertCountedElement(src, length, dst, flags)
    CONST char *src;            /* Source information for list element. */
    int length;                 /* Number of bytes in src, or -1. */
    char *dst;                  /* Place to put list-ified element. */
    int flags;                  /* Flags produced by Tcl_ScanElement. */
{
    char *p = dst;
    CONST char *lastChar;

    /*
     * See the comment block at the beginning of the Tcl_ScanElement
     * code for details of how this works.
     */

    if (src && length == -1) {
        length = strlen(src);
    }
    if ((src == NULL) || (length == 0)) {
        p[0] = '{';
        p[1] = '}';
        p[2] = 0;
        return 2;
    }
    lastChar = src + length;
    if ((flags & USE_BRACES) && !(flags & TCL_DONT_USE_BRACES)) {
        *p = '{';
        p++;
        for ( ; src != lastChar; src++, p++) {
            *p = *src;
        }
        *p = '}';
        p++;
    } else {
        if (*src == '{') {
            /*
             * Can't have a leading brace unless the whole element is
             * enclosed in braces.  Add a backslash before the brace.
             * Furthermore, this may destroy the balance between open
             * and close braces, so set BRACES_UNMATCHED.
             */

            p[0] = '\\';
            p[1] = '{';
            p += 2;
            src++;
            flags |= BRACES_UNMATCHED;
        }
        for (; src != lastChar; src++) {
            switch (*src) {
                case ']':
                case '[':
                case '$':
                case ';':
                case ' ':
                case '\\':
                case '"':
                    *p = '\\';
                    p++;
                    break;
                case '{':
                case '}':
                    /*
                     * It may not seem necessary to backslash braces, but
                     * it is.  The reason for this is that the resulting
                     * list element may actually be an element of a sub-list
                     * enclosed in braces (e.g. if Tcl_DStringStartSublist
                     * has been invoked), so there may be a brace mismatch
                     * if the braces aren't backslashed.
                     */

                    if (flags & BRACES_UNMATCHED) {
                        *p = '\\';
                        p++;
                    }
                    break;
                case '\f':
                    *p = '\\';
                    p++;
                    *p = 'f';
                    p++;
                    continue;
                case '\n':
                    *p = '\\';
                    p++;
                    *p = 'n';
                    p++;
                    continue;
                case '\r':
                    *p = '\\';
                    p++;
                    *p = 'r';
                    p++;
                    continue;
                case '\t':
                    *p = '\\';
                    p++;
                    *p = 't';
                    p++;
                    continue;
                case '\v':
                    *p = '\\';
                    p++;
                    *p = 'v';
                    p++;
                    continue;
            }
            *p = *src;
            p++;
        }
    }
    *p = '\0';
    return p-dst;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_Merge --
 *
 *      Given a collection of strings, merge them together into a
 *      single string that has proper Tcl list structured (i.e.
 *      Tcl_SplitList may be used to retrieve strings equal to the
 *      original elements, and Tcl_Eval will parse the string back
 *      into its original elements).
 *
 * Results:
 *      The return value is the address of a dynamically-allocated
 *      string containing the merged list.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

char *
Tcl_Merge(argc, argv)
    int argc;                   /* How many strings to merge. */
    char **argv;                /* Array of string values. */
{
#   define LOCAL_SIZE 20
    int localFlags[LOCAL_SIZE], *flagPtr;
    int numChars;
    char *result;
    char *dst;
    int i;

    /*
     * Pass 1: estimate space, gather flags.
     */

    if (argc <= LOCAL_SIZE) {
        flagPtr = localFlags;
    } else {
        flagPtr = (int *) ckalloc((unsigned) argc*sizeof(int));
    }
    numChars = 1;
    for (i = 0; i < argc; i++) {
        numChars += Tcl_ScanElement(argv[i], &flagPtr[i]) + 1;
    }

    /*
     * Pass two: copy into the result area.
     */

    result = (char *) ckalloc((unsigned) numChars);
    dst = result;
    for (i = 0; i < argc; i++) {
        numChars = Tcl_ConvertElement(argv[i], dst, flagPtr[i]);
        dst += numChars;
        *dst = ' ';
        dst++;
    }
    if (dst == result) {
        *dst = 0;
    } else {
        dst[-1] = 0;
    }

    if (flagPtr != localFlags) {
        ckfree((char *) flagPtr);
    }
    return result;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_Concat --
 *
 *      Concatenate a set of strings into a single large string.
 *
 * Results:
 *      The return value is dynamically-allocated string containing
 *      a concatenation of all the strings in argv, with spaces between
 *      the original argv elements.
 *
 * Side effects:
 *      Memory is allocated for the result;  the caller is responsible
 *      for freeing the memory.
 *
 *----------------------------------------------------------------------
 */

char *
Tcl_Concat(argc, argv)
    int argc;                   /* Number of strings to concatenate. */
    char **argv;                /* Array of strings to concatenate. */
{
    int totalSize, i;
    char *p;
    char *result;

    for (totalSize = 1, i = 0; i < argc; i++) {
        totalSize += strlen(argv[i]) + 1;
    }
    result = (char *) ckalloc((unsigned) totalSize);
    if (argc == 0) {
        *result = '\0';
        return result;
    }
    for (p = result, i = 0; i < argc; i++) {
        char *element;
        int length;

        /*
         * Clip white space off the front and back of the string
         * to generate a neater result, and ignore any empty
         * elements.
         */

        element = argv[i];
        while (isspace(UCHAR(*element))) {
            element++;
        }
        for (length = strlen(element);
                (length > 0) && (isspace(UCHAR(element[length-1])))
                && ((length < 2) || (element[length-2] != '\\'));
                length--) {
            /* Null loop body. */
        }
        if (length == 0) {
            continue;
        }
        memcpy((VOID *) p, (VOID *) element, (size_t) length);
        p += length;
        *p = ' ';
        p++;
    }
    if (p != result) {
        p[-1] = 0;
    } else {
        *p = 0;
    }
    return result;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_ConcatObj --
 *
 *      Concatenate the strings from a set of objects into a single string
 *      object with spaces between the original strings.
 *
 * Results:
 *      The return value is a new string object containing a concatenation
 *      of the strings in objv. Its ref count is zero.
 *
 * Side effects:
 *      A new object is created.
 *
 *----------------------------------------------------------------------
 */

Tcl_Obj *
Tcl_ConcatObj(objc, objv)
    int objc;                   /* Number of objects to concatenate. */
    Tcl_Obj *CONST objv[];      /* Array of objects to concatenate. */
{
    int allocSize, finalSize, length, elemLength, i;
    char *p;
    char *element;
    char *concatStr;
    Tcl_Obj *objPtr;

    allocSize = 0;
    for (i = 0;  i < objc;  i++) {
        objPtr = objv[i];
        element = TclGetStringFromObj(objPtr, &length);
        if ((element != NULL) && (length > 0)) {
            allocSize += (length + 1);
        }
    }
    if (allocSize == 0) {
        allocSize = 1;          /* enough for the NULL byte at end */
    }

    /*
     * Allocate storage for the concatenated result. Note that allocSize
     * is one more than the total number of characters, and so includes
     * room for the terminating NULL byte.
     */
    
    concatStr = (char *) ckalloc((unsigned) allocSize);

    /*
     * Now concatenate the elements. Clip white space off the front and back
     * to generate a neater result, and ignore any empty elements. Also put
     * a null byte at the end.
     */

    finalSize = 0;
    if (objc == 0) {
        *concatStr = '\0';
    } else {
        p = concatStr;
        for (i = 0;  i < objc;  i++) {
            objPtr = objv[i];
            element = TclGetStringFromObj(objPtr, &elemLength);
            while ((elemLength > 0) && (isspace(UCHAR(*element)))) {
                 element++;
                 elemLength--;
            }

            /*
             * Trim trailing white space.  But, be careful not to trim
             * a space character if it is preceded by a backslash: in
             * this case it could be significant.
             */

            while ((elemLength > 0)
                    && isspace(UCHAR(element[elemLength-1]))
                    && ((elemLength < 2) || (element[elemLength-2] != '\\'))) {
                elemLength--;
            }
            if (elemLength == 0) {
                 continue;      /* nothing left of this element */
            }
            memcpy((VOID *) p, (VOID *) element, (size_t) elemLength);
            p += elemLength;
            *p = ' ';
            p++;
            finalSize += (elemLength + 1);
        }
        if (p != concatStr) {
            p[-1] = 0;
            finalSize -= 1;     /* we overwrote the final ' ' */
        } else {
            *p = 0;
        }
    }
    
    TclNewObj(objPtr);
    objPtr->bytes  = concatStr;
    objPtr->length = finalSize;
    return objPtr;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_StringMatch --
 *
 *      See if a particular string matches a particular pattern.
 *
 * Results:
 *      The return value is 1 if string matches pattern, and
 *      0 otherwise.  The matching operation permits the following
 *      special characters in the pattern: *?\[] (see the manual
 *      entry for details on what these mean).
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_StringMatch(string, pattern)
    char *string;               /* String. */
    char *pattern;              /* Pattern, which may contain special
                                 * characters. */
{
    char c2;

    while (1) {
        /* See if we're at the end of both the pattern and the string.
         * If so, we succeeded.  If we're at the end of the pattern
         * but not at the end of the string, we failed.
         */
        
        if (*pattern == 0) {
            if (*string == 0) {
                return 1;
            } else {
                return 0;
            }
        }
        if ((*string == 0) && (*pattern != '*')) {
            return 0;
        }

        /* Check for a "*" as the next pattern character.  It matches
         * any substring.  We handle this by calling ourselves
         * recursively for each postfix of string, until either we
         * match or we reach the end of the string.
         */
        
        if (*pattern == '*') {
            pattern += 1;
            if (*pattern == 0) {
                return 1;
            }
            while (1) {
                if (Tcl_StringMatch(string, pattern)) {
                    return 1;
                }
                if (*string == 0) {
                    return 0;
                }
                string += 1;
            }
        }
    
        /* Check for a "?" as the next pattern character.  It matches
         * any single character.
         */

        if (*pattern == '?') {
            goto thisCharOK;
        }

        /* Check for a "[" as the next pattern character.  It is followed
         * by a list of characters that are acceptable, or by a range
         * (two characters separated by "-").
         */
        
        if (*pattern == '[') {
            pattern += 1;
            while (1) {
                if ((*pattern == ']') || (*pattern == 0)) {
                    return 0;
                }
                if (*pattern == *string) {
                    break;
                }
                if (pattern[1] == '-') {
                    c2 = pattern[2];
                    if (c2 == 0) {
                        return 0;
                    }
                    if ((*pattern <= *string) && (c2 >= *string)) {
                        break;
                    }
                    if ((*pattern >= *string) && (c2 <= *string)) {
                        break;
                    }
                    pattern += 2;
                }
                pattern += 1;
            }
            while (*pattern != ']') {
                if (*pattern == 0) {
                    pattern--;
                    break;
                }
                pattern += 1;
            }
            goto thisCharOK;
        }
    
        /* If the next pattern character is '/', just strip off the '/'
         * so we do exact matching on the character that follows.
         */
        
        if (*pattern == '\\') {
            pattern += 1;
            if (*pattern == 0) {
                return 0;
            }
        }

        /* There's no special character.  Just make sure that the next
         * characters of each string match.
         */
        
        if (*pattern != *string) {
            return 0;
        }

        thisCharOK: pattern += 1;
        string += 1;
    }
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_SetResult --
 *
 *      Arrange for "string" to be the Tcl return value.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      interp->result is left pointing either to "string" (if "copy" is 0)
 *      or to a copy of string. Also, the object result is reset.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_SetResult(interp, string, freeProc)
    Tcl_Interp *interp;         /* Interpreter with which to associate the
                                 * return value. */
    char *string;               /* Value to be returned.  If NULL, the
                                 * result is set to an empty string. */
    Tcl_FreeProc *freeProc;     /* Gives information about the string:
                                 * TCL_STATIC, TCL_VOLATILE, or the address
                                 * of a Tcl_FreeProc such as free. */
{
    Interp *iPtr = (Interp *) interp;
    int length;
    Tcl_FreeProc *oldFreeProc = iPtr->freeProc;
    char *oldResult = iPtr->result;

    if (string == NULL) {
        iPtr->resultSpace[0] = 0;
        iPtr->result = iPtr->resultSpace;
        iPtr->freeProc = 0;
    } else if (freeProc == TCL_VOLATILE) {
        length = strlen(string);
        if (length > TCL_RESULT_SIZE) {
            iPtr->result = (char *) ckalloc((unsigned) length+1);
            iPtr->freeProc = TCL_DYNAMIC;
        } else {
            iPtr->result = iPtr->resultSpace;
            iPtr->freeProc = 0;
        }
        strcpy(iPtr->result, string);
    } else {
        iPtr->result = string;
        iPtr->freeProc = freeProc;
    }

    /*
     * If the old result was dynamically-allocated, free it up.  Do it
     * here, rather than at the beginning, in case the new result value
     * was part of the old result value.
     */

    if (oldFreeProc != 0) {
        if ((oldFreeProc == TCL_DYNAMIC)
                || (oldFreeProc == (Tcl_FreeProc *) free)) {
            ckfree(oldResult);
        } else {
            (*oldFreeProc)(oldResult);
        }
    }

    /*
     * Reset the object result since we just set the string result.
     */

    TclResetObjResult(iPtr);
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_GetStringResult --
 *
 *      Returns an interpreter's result value as a string.
 *
 * Results:
 *      The interpreter's result as a string.
 *
 * Side effects:
 *      If the string result is empty, the object result is moved to the
 *      string result, then the object result is reset.
 *
 *----------------------------------------------------------------------
 */

char *
Tcl_GetStringResult(interp)
     Tcl_Interp *interp;        /* Interpreter whose result to return. */
{
    /*
     * If the string result is empty, move the object result to the
     * string result, then reset the object result.
     * FAILS IF OBJECT RESULT'S STRING REPRESENTATION CONTAINS NULLS.
     */
    
    if (*(interp->result) == 0) {
        Tcl_SetResult(interp,
                TclGetStringFromObj(Tcl_GetObjResult(interp), (int *) NULL),
                TCL_VOLATILE);
    }
    return interp->result;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_SetObjResult --
 *
 *      Arrange for objPtr to be an interpreter's result value.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      interp->objResultPtr is left pointing to the object referenced
 *      by objPtr. The object's reference count is incremented since
 *      there is now a new reference to it. The reference count for any
 *      old objResultPtr value is decremented. Also, the string result
 *      is reset.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_SetObjResult(interp, objPtr)
    Tcl_Interp *interp;         /* Interpreter with which to associate the
                                 * return object value. */
    Tcl_Obj *objPtr;            /* Tcl object to be returned. If NULL, the
                                 * obj result is made an empty string
                                 * object. */
{
    Interp *iPtr = (Interp *) interp;
    Tcl_Obj *oldObjResult = iPtr->objResultPtr;

    iPtr->objResultPtr = objPtr;
    Tcl_IncrRefCount(objPtr);   /* since interp result is a reference */

    /*
     * We wait until the end to release the old object result, in case
     * we are setting the result to itself.
     */
    
    TclDecrRefCount(oldObjResult);

    /*
     * Reset the string result since we just set the result object.
     */

    if (iPtr->freeProc != NULL) {
        if ((iPtr->freeProc == TCL_DYNAMIC)
                || (iPtr->freeProc == (Tcl_FreeProc *) free)) {
            ckfree(iPtr->result);
        } else {
            (*iPtr->freeProc)(iPtr->result);
        }
        iPtr->freeProc = 0;
    }
    iPtr->result = iPtr->resultSpace;
    iPtr->resultSpace[0] = 0;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_GetObjResult --
 *
 *      Returns an interpreter's result value as a Tcl object. The object's
 *      reference count is not modified; the caller must do that if it
 *      needs to hold on to a long-term reference to it.
 *
 * Results:
 *      The interpreter's result as an object.
 *
 * Side effects:
 *      If the interpreter has a non-empty string result, the result object
 *      is either empty or stale because some procedure set interp->result
 *      directly. If so, the string result is moved to the result object
 *      then the string result is reset.
 *
 *----------------------------------------------------------------------
 */

Tcl_Obj *
Tcl_GetObjResult(interp)
    Tcl_Interp *interp;         /* Interpreter whose result to return. */
{
    Interp *iPtr = (Interp *) interp;
    Tcl_Obj *objResultPtr;
    int length;

    /*
     * If the string result is non-empty, move the string result to the
     * object result, then reset the string result.
     */
    
    if (*(iPtr->result) != 0) {
        TclResetObjResult(iPtr);
        
        objResultPtr = iPtr->objResultPtr;
        length = strlen(iPtr->result);
        TclInitStringRep(objResultPtr, iPtr->result, length);
        
        if (iPtr->freeProc != NULL) {
            if ((iPtr->freeProc == TCL_DYNAMIC)
                    || (iPtr->freeProc == (Tcl_FreeProc *) free)) {
                ckfree(iPtr->result);
            } else {
                (*iPtr->freeProc)(iPtr->result);
            }
            iPtr->freeProc = 0;
        }
        iPtr->result = iPtr->resultSpace;
        iPtr->resultSpace[0] = 0;
    }
    return iPtr->objResultPtr;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_AppendResult --
 *
 *      Append a variable number of strings onto the interpreter's string
 *      result.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The result of the interpreter given by the first argument is
 *      extended by the strings given by the second and following arguments
 *      (up to a terminating NULL argument).
 *
 *      If the string result is empty, the object result is moved to the
 *      string result, then the object result is reset.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_AppendResult TCL_VARARGS_DEF(Tcl_Interp *,arg1)
{
    va_list argList;
    Interp *iPtr;
    char *string;
    int newSpace;

    /*
     * If the string result is empty, move the object result to the
     * string result, then reset the object result.
     * FAILS IF OBJECT RESULT'S STRING REPRESENTATION CONTAINS NULLS.
     */

    iPtr = (Interp *) TCL_VARARGS_START(Tcl_Interp *,arg1,argList);
    if (*(iPtr->result) == 0) {
        Tcl_SetResult((Tcl_Interp *) iPtr,
                TclGetStringFromObj(Tcl_GetObjResult((Tcl_Interp *) iPtr),
                        (int *) NULL),
                TCL_VOLATILE);
    }
    
    /*
     * Scan through all the arguments to see how much space is needed.
     */

    newSpace = 0;
    while (1) {
        string = va_arg(argList, char *);
        if (string == NULL) {
            break;
        }
        newSpace += strlen(string);
    }
    va_end(argList);

    /*
     * If the append buffer isn't already setup and large enough to hold
     * the new data, set it up.
     */

    if ((iPtr->result != iPtr->appendResult)
            || (iPtr->appendResult[iPtr->appendUsed] != 0)
            || ((newSpace + iPtr->appendUsed) >= iPtr->appendAvl)) {
       SetupAppendBuffer(iPtr, newSpace);
    }

    /*
     * Now go through all the argument strings again, copying them into the
     * buffer.
     */

    TCL_VARARGS_START(Tcl_Interp *,arg1,argList);
    while (1) {
        string = va_arg(argList, char *);
        if (string == NULL) {
            break;
        }
        strcpy(iPtr->appendResult + iPtr->appendUsed, string);
        iPtr->appendUsed += strlen(string);
    }
    va_end(argList);
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_AppendElement --
 *
 *      Convert a string to a valid Tcl list element and append it to the
 *      result (which is ostensibly a list).
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The result in the interpreter given by the first argument is
 *      extended with a list element converted from string. A separator
 *      space is added before the converted list element unless the current
 *      result is empty, contains the single character "{", or ends in " {".
 *
 *      If the string result is empty, the object result is moved to the
 *      string result, then the object result is reset.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_AppendElement(interp, string)
    Tcl_Interp *interp;         /* Interpreter whose result is to be
                                 * extended. */
    char *string;               /* String to convert to list element and
                                 * add to result. */
{
    Interp *iPtr = (Interp *) interp;
    char *dst;
    int size;
    int flags;

    /*
     * If the string result is empty, move the object result to the
     * string result, then reset the object result.
     * FAILS IF OBJECT RESULT'S STRING REPRESENTATION CONTAINS NULLS.
     */

    if (*(iPtr->result) == 0) {
        Tcl_SetResult(interp,
                TclGetStringFromObj(Tcl_GetObjResult(interp), (int *) NULL),
                TCL_VOLATILE);
    }

    /*
     * See how much space is needed, and grow the append buffer if
     * needed to accommodate the list element.
     */

    size = Tcl_ScanElement(string, &flags) + 1;
    if ((iPtr->result != iPtr->appendResult)
            || (iPtr->appendResult[iPtr->appendUsed] != 0)
            || ((size + iPtr->appendUsed) >= iPtr->appendAvl)) {
       SetupAppendBuffer(iPtr, size+iPtr->appendUsed);
    }

    /*
     * Convert the string into a list element and copy it to the
     * buffer that's forming, with a space separator if needed.
     */

    dst = iPtr->appendResult + iPtr->appendUsed;
    if (TclNeedSpace(iPtr->appendResult, dst)) {
        iPtr->appendUsed++;
        *dst = ' ';
        dst++;
    }
    iPtr->appendUsed += Tcl_ConvertElement(string, dst, flags);
}


/*
 *----------------------------------------------------------------------
 *
 * SetupAppendBuffer --
 *
 *      This procedure makes sure that there is an append buffer properly
 *      initialized, if necessary, from the interpreter's result, and
 *      that it has at least enough room to accommodate newSpace new
 *      bytes of information.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

static void
SetupAppendBuffer(iPtr, newSpace)
    Interp *iPtr;               /* Interpreter whose result is being set up. */
    int newSpace;               /* Make sure that at least this many bytes
                                 * of new information may be added. */
{
    int totalSpace;

    /*
     * Make the append buffer larger, if that's necessary, then copy the
     * result into the append buffer and make the append buffer the official
     * Tcl result.
     */

    if (iPtr->result != iPtr->appendResult) {
        /*
         * If an oversized buffer was used recently, then free it up
         * so we go back to a smaller buffer.  This avoids tying up
         * memory forever after a large operation.
         */

        if (iPtr->appendAvl > 500) {
            ckfree(iPtr->appendResult);
            iPtr->appendResult = NULL;
            iPtr->appendAvl = 0;
        }
        iPtr->appendUsed = strlen(iPtr->result);
    } else if (iPtr->result[iPtr->appendUsed] != 0) {
        /*
         * Most likely someone has modified a result created by
         * Tcl_AppendResult et al. so that it has a different size.
         * Just recompute the size.
         */

        iPtr->appendUsed = strlen(iPtr->result);
    }
    
    totalSpace = newSpace + iPtr->appendUsed;
    if (totalSpace >= iPtr->appendAvl) {
        char *new;

        if (totalSpace < 100) {
            totalSpace = 200;
        } else {
            totalSpace *= 2;
        }
        new = (char *) ckalloc((unsigned) totalSpace);
        strcpy(new, iPtr->result);
        if (iPtr->appendResult != NULL) {
            ckfree(iPtr->appendResult);
        }
        iPtr->appendResult = new;
        iPtr->appendAvl = totalSpace;
    } else if (iPtr->result != iPtr->appendResult) {
        strcpy(iPtr->appendResult, iPtr->result);
    }
    
    Tcl_FreeResult((Tcl_Interp *) iPtr);
    iPtr->result = iPtr->appendResult;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_FreeResult --
 *
 *      This procedure frees up the memory associated with an interpreter's
 *      string result. It also resets the interpreter's result object.
 *      Tcl_FreeResult is most commonly used when a procedure is about to
 *      replace one result value with another.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Frees the memory associated with interp's string result and sets
 *      interp->freeProc to zero, but does not change interp->result or
 *      clear error state. Resets interp's result object to an unshared
 *      empty object.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_FreeResult(interp)
    Tcl_Interp *interp;         /* Interpreter for which to free result. */
{
    Interp *iPtr = (Interp *) interp;
    
    if (iPtr->freeProc != NULL) {
        if ((iPtr->freeProc == TCL_DYNAMIC)
                || (iPtr->freeProc == (Tcl_FreeProc *) free)) {
            ckfree(iPtr->result);
        } else {
            (*iPtr->freeProc)(iPtr->result);
        }
        iPtr->freeProc = 0;
    }
    
    TclResetObjResult(iPtr);
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_ResetResult --
 *
 *      This procedure resets both the interpreter's string and object
 *      results.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      It resets the result object to an unshared empty object. It
 *      then restores the interpreter's string result area to its default
 *      initialized state, freeing up any memory that may have been
 *      allocated. It also clears any error information for the interpreter.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_ResetResult(interp)
    Tcl_Interp *interp;         /* Interpreter for which to clear result. */
{
    Interp *iPtr = (Interp *) interp;

    TclResetObjResult(iPtr);
    
    Tcl_FreeResult(interp);
    iPtr->result = iPtr->resultSpace;
    iPtr->resultSpace[0] = 0;
    
    iPtr->flags &= ~(ERR_ALREADY_LOGGED | ERR_IN_PROGRESS | ERROR_CODE_SET);
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_SetErrorCode --
 *
 *      This procedure is called to record machine-readable information
 *      about an error that is about to be returned.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The errorCode global variable is modified to hold all of the
 *      arguments to this procedure, in a list form with each argument
 *      becoming one element of the list.  A flag is set internally
 *      to remember that errorCode has been set, so the variable doesn't
 *      get set automatically when the error is returned.
 *
 *----------------------------------------------------------------------
 */
        /* VARARGS2 */
void
Tcl_SetErrorCode TCL_VARARGS_DEF(Tcl_Interp *,arg1)
{
    va_list argList;
    char *string;
    int flags;
    Interp *iPtr;

    /*
     * Scan through the arguments one at a time, appending them to
     * $errorCode as list elements.
     */

    iPtr = (Interp *) TCL_VARARGS_START(Tcl_Interp *,arg1,argList);
    flags = TCL_GLOBAL_ONLY | TCL_LIST_ELEMENT;
    while (1) {
        string = va_arg(argList, char *);
        if (string == NULL) {
            break;
        }
        (void) Tcl_SetVar2((Tcl_Interp *) iPtr, "errorCode",
                (char *) NULL, string, flags);
        flags |= TCL_APPEND_VALUE;
    }
    va_end(argList);
    iPtr->flags |= ERROR_CODE_SET;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_SetObjErrorCode --
 *
 *      This procedure is called to record machine-readable information
 *      about an error that is about to be returned. The caller should
 *      build a list object up and pass it to this routine.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The errorCode global variable is modified to be the new value.
 *      A flag is set internally to remember that errorCode has been
 *      set, so the variable doesn't get set automatically when the
 *      error is returned.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_SetObjErrorCode(interp, errorObjPtr)
    Tcl_Interp *interp;
    Tcl_Obj *errorObjPtr;
{
    Tcl_Obj *namePtr;
    Interp *iPtr;
    
    namePtr = Tcl_NewStringObj("errorCode", -1);
    iPtr = (Interp *) interp;
    Tcl_ObjSetVar2(interp, namePtr, (Tcl_Obj *) NULL, errorObjPtr,
            TCL_GLOBAL_ONLY);
    iPtr->flags |= ERROR_CODE_SET;
    Tcl_DecrRefCount(namePtr);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_DStringInit --
 *
 *      Initializes a dynamic string, discarding any previous contents
 *      of the string (Tcl_DStringFree should have been called already
 *      if the dynamic string was previously in use).
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The dynamic string is initialized to be empty.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_DStringInit(dsPtr)
    Tcl_DString *dsPtr;         /* Pointer to structure for dynamic string. */
{
    dsPtr->string = dsPtr->staticSpace;
    dsPtr->length = 0;
    dsPtr->spaceAvl = TCL_DSTRING_STATIC_SIZE;
    dsPtr->staticSpace[0] = 0;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_DStringAppend --
 *
 *      Append more characters to the current value of a dynamic string.
 *
 * Results:
 *      The return value is a pointer to the dynamic string's new value.
 *
 * Side effects:
 *      Length bytes from string (or all of string if length is less
 *      than zero) are added to the current value of the string. Memory
 *      gets reallocated if needed to accomodate the string's new size.
 *
 *----------------------------------------------------------------------
 */

char *
Tcl_DStringAppend(dsPtr, string, length)
    Tcl_DString *dsPtr;         /* Structure describing dynamic string. */
    CONST char *string;         /* String to append.  If length is -1 then
                                 * this must be null-terminated. */
    int length;                 /* Number of characters from string to
                                 * append.  If < 0, then append all of string,
                                 * up to null at end. */
{
    int newSize;
    char *newString, *dst;
    CONST char *end;

    if (length < 0) {
        length = strlen(string);
    }
    newSize = length + dsPtr->length;

    /*
     * Allocate a larger buffer for the string if the current one isn't
     * large enough. Allocate extra space in the new buffer so that there
     * will be room to grow before we have to allocate again.
     */

    if (newSize >= dsPtr->spaceAvl) {
        dsPtr->spaceAvl = newSize*2;
        newString = (char *) ckalloc((unsigned) dsPtr->spaceAvl);
        memcpy((VOID *) newString, (VOID *) dsPtr->string,
                (size_t) dsPtr->length);
        if (dsPtr->string != dsPtr->staticSpace) {
            ckfree(dsPtr->string);
        }
        dsPtr->string = newString;
    }

    /*
     * Copy the new string into the buffer at the end of the old
     * one.
     */

    for (dst = dsPtr->string + dsPtr->length, end = string+length;
            string < end; string++, dst++) {
        *dst = *string;
    }
    *dst = '\0';
    dsPtr->length += length;
    return dsPtr->string;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_DStringAppendElement --
 *
 *      Append a list element to the current value of a dynamic string.
 *
 * Results:
 *      The return value is a pointer to the dynamic string's new value.
 *
 * Side effects:
 *      String is reformatted as a list element and added to the current
 *      value of the string.  Memory gets reallocated if needed to
 *      accomodate the string's new size.
 *
 *----------------------------------------------------------------------
 */

char *
Tcl_DStringAppendElement(dsPtr, string)
    Tcl_DString *dsPtr;         /* Structure describing dynamic string. */
    CONST char *string;         /* String to append.  Must be
                                 * null-terminated. */
{
    int newSize, flags;
    char *dst, *newString;

    newSize = Tcl_ScanElement(string, &flags) + dsPtr->length + 1;

    /*
     * Allocate a larger buffer for the string if the current one isn't
     * large enough.  Allocate extra space in the new buffer so that there
     * will be room to grow before we have to allocate again.
     * SPECIAL NOTE: must use memcpy, not strcpy, to copy the string
     * to a larger buffer, since there may be embedded NULLs in the
     * string in some cases.
     */

    if (newSize >= dsPtr->spaceAvl) {
        dsPtr->spaceAvl = newSize*2;
        newString = (char *) ckalloc((unsigned) dsPtr->spaceAvl);
        memcpy((VOID *) newString, (VOID *) dsPtr->string,
                (size_t) dsPtr->length);
        if (dsPtr->string != dsPtr->staticSpace) {
            ckfree(dsPtr->string);
        }
        dsPtr->string = newString;
    }

    /*
     * Convert the new string to a list element and copy it into the
     * buffer at the end, with a space, if needed.
     */

    dst = dsPtr->string + dsPtr->length;
    if (TclNeedSpace(dsPtr->string, dst)) {
        *dst = ' ';
        dst++;
        dsPtr->length++;
    }
    dsPtr->length += Tcl_ConvertElement(string, dst, flags);
    return dsPtr->string;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_DStringSetLength --
 *
 *      Change the length of a dynamic string.  This can cause the
 *      string to either grow or shrink, depending on the value of
 *      length.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The length of dsPtr is changed to length and a null byte is
 *      stored at that position in the string.  If length is larger
 *      than the space allocated for dsPtr, then a panic occurs.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_DStringSetLength(dsPtr, length)
    Tcl_DString *dsPtr;         /* Structure describing dynamic string. */
    int length;                 /* New length for dynamic string. */
{
    if (length < 0) {
        length = 0;
    }
    if (length >= dsPtr->spaceAvl) {
        char *newString;

        dsPtr->spaceAvl = length+1;
        newString = (char *) ckalloc((unsigned) dsPtr->spaceAvl);

        /*
         * SPECIAL NOTE: must use memcpy, not strcpy, to copy the string
         * to a larger buffer, since there may be embedded NULLs in the
         * string in some cases.
         */

        memcpy((VOID *) newString, (VOID *) dsPtr->string,
                (size_t) dsPtr->length);
        if (dsPtr->string != dsPtr->staticSpace) {
            ckfree(dsPtr->string);
        }
        dsPtr->string = newString;
    }
    dsPtr->length = length;
    dsPtr->string[length] = 0;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_DStringFree --
 *
 *      Frees up any memory allocated for the dynamic string and
 *      reinitializes the string to an empty state.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The previous contents of the dynamic string are lost, and
 *      the new value is an empty string.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_DStringFree(dsPtr)
    Tcl_DString *dsPtr;         /* Structure describing dynamic string. */
{
    if (dsPtr->string != dsPtr->staticSpace) {
        ckfree(dsPtr->string);
    }
    dsPtr->string = dsPtr->staticSpace;
    dsPtr->length = 0;
    dsPtr->spaceAvl = TCL_DSTRING_STATIC_SIZE;
    dsPtr->staticSpace[0] = 0;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_DStringResult --
 *
 *      This procedure moves the value of a dynamic string into an
 *      interpreter as its string result. Afterwards, the dynamic string
 *      is reset to an empty string.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The string is "moved" to interp's result, and any existing
 *      string result for interp is freed. dsPtr is reinitialized to
 *      an empty string.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_DStringResult(interp, dsPtr)
    Tcl_Interp *interp;         /* Interpreter whose result is to be reset. */
    Tcl_DString *dsPtr;         /* Dynamic string that is to become the
                                 * result of interp. */
{
    Tcl_ResetResult(interp);
    
    if (dsPtr->string != dsPtr->staticSpace) {
        interp->result = dsPtr->string;
        interp->freeProc = TCL_DYNAMIC;
    } else if (dsPtr->length < TCL_RESULT_SIZE) {
        interp->result = ((Interp *) interp)->resultSpace;
        strcpy(interp->result, dsPtr->string);
    } else {
        Tcl_SetResult(interp, dsPtr->string, TCL_VOLATILE);
    }
    
    dsPtr->string = dsPtr->staticSpace;
    dsPtr->length = 0;
    dsPtr->spaceAvl = TCL_DSTRING_STATIC_SIZE;
    dsPtr->staticSpace[0] = 0;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_DStringGetResult --
 *
 *      This procedure moves an interpreter's result into a dynamic string.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The interpreter's string result is cleared, and the previous
 *      contents of dsPtr are freed.
 *
 *      If the string result is empty, the object result is moved to the
 *      string result, then the object result is reset.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_DStringGetResult(interp, dsPtr)
    Tcl_Interp *interp;         /* Interpreter whose result is to be reset. */
    Tcl_DString *dsPtr;         /* Dynamic string that is to become the
                                 * result of interp. */
{
    Interp *iPtr = (Interp *) interp;
    
    if (dsPtr->string != dsPtr->staticSpace) {
        ckfree(dsPtr->string);
    }

    /*
     * If the string result is empty, move the object result to the
     * string result, then reset the object result.
     * FAILS IF OBJECT RESULT'S STRING REPRESENTATION CONTAINS NULLS.
     */

    if (*(iPtr->result) == 0) {
        Tcl_SetResult(interp,
                TclGetStringFromObj(Tcl_GetObjResult(interp), (int *) NULL),
                TCL_VOLATILE);
    }

    dsPtr->length = strlen(iPtr->result);
    if (iPtr->freeProc != NULL) {
        if ((iPtr->freeProc == TCL_DYNAMIC)
                || (iPtr->freeProc == (Tcl_FreeProc *) free)) {
            dsPtr->string = iPtr->result;
            dsPtr->spaceAvl = dsPtr->length+1;
        } else {
            dsPtr->string = (char *) ckalloc((unsigned) (dsPtr->length+1));
            strcpy(dsPtr->string, iPtr->result);
            (*iPtr->freeProc)(iPtr->result);
        }
        dsPtr->spaceAvl = dsPtr->length+1;
        iPtr->freeProc = NULL;
    } else {
        if (dsPtr->length < TCL_DSTRING_STATIC_SIZE) {
            dsPtr->string = dsPtr->staticSpace;
            dsPtr->spaceAvl = TCL_DSTRING_STATIC_SIZE;
        } else {
            dsPtr->string = (char *) ckalloc((unsigned) (dsPtr->length + 1));
            dsPtr->spaceAvl = dsPtr->length + 1;
        }
        strcpy(dsPtr->string, iPtr->result);
    }
    
    iPtr->result = iPtr->resultSpace;
    iPtr->resultSpace[0] = 0;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_DStringStartSublist --
 *
 *      This procedure adds the necessary information to a dynamic
 *      string (e.g. " {" to start a sublist.  Future element
 *      appends will be in the sublist rather than the main list.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Characters get added to the dynamic string.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_DStringStartSublist(dsPtr)
    Tcl_DString *dsPtr;                 /* Dynamic string. */
{
    if (TclNeedSpace(dsPtr->string, dsPtr->string + dsPtr->length)) {
        Tcl_DStringAppend(dsPtr, " {", -1);
    } else {
        Tcl_DStringAppend(dsPtr, "{", -1);
    }
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_DStringEndSublist --
 *
 *      This procedure adds the necessary characters to a dynamic
 *      string to end a sublist (e.g. "}").  Future element appends
 *      will be in the enclosing (sub)list rather than the current
 *      sublist.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_DStringEndSublist(dsPtr)
    Tcl_DString *dsPtr;                 /* Dynamic string. */
{
    Tcl_DStringAppend(dsPtr, "}", -1);
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_PrintDouble --
 *
 *      Given a floating-point value, this procedure converts it to
 *      an ASCII string using.
 *
 * Results:
 *      The ASCII equivalent of "value" is written at "dst".  It is
 *      written using the current precision, and it is guaranteed to
 *      contain a decimal point or exponent, so that it looks like
 *      a floating-point value and not an integer.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_PrintDouble(interp, value, dst)
    Tcl_Interp *interp;                 /* Interpreter whose tcl_precision
                                         * variable used to be used to control
                                         * printing.  It's ignored now. */
    double value;                       /* Value to print as string. */
    char *dst;                          /* Where to store converted value;
                                         * must have at least TCL_DOUBLE_SPACE
                                         * characters. */
{
    char *p;

    sprintf(dst, precisionFormat, value);

    /*
     * If the ASCII result looks like an integer, add ".0" so that it
     * doesn't look like an integer anymore.  This prevents floating-point
     * values from being converted to integers unintentionally.
     */

    for (p = dst; *p != 0; p++) {
        if ((*p == '.') || (isalpha(UCHAR(*p)))) {
            return;
        }
    }
    p[0] = '.';
    p[1] = '0';
    p[2] = 0;
}


/*
 *----------------------------------------------------------------------
 *
 * TclPrecTraceProc --
 *
 *      This procedure is invoked whenever the variable "tcl_precision"
 *      is written.
 *
 * Results:
 *      Returns NULL if all went well, or an error message if the
 *      new value for the variable doesn't make sense.
 *
 * Side effects:
 *      If the new value doesn't make sense then this procedure
 *      undoes the effect of the variable modification.  Otherwise
 *      it modifies the format string that's used by Tcl_PrintDouble.
 *
 *----------------------------------------------------------------------
 */

        /* ARGSUSED */
char *
TclPrecTraceProc(clientData, interp, name1, name2, flags)
    ClientData clientData;      /* Not used. */
    Tcl_Interp *interp;         /* Interpreter containing variable. */
    char *name1;                /* Name of variable. */
    char *name2;                /* Second part of variable name. */
    int flags;                  /* Information about what happened. */
{
    char *value, *end;
    int prec;

    /*
     * If the variable is unset, then recreate the trace.
     */

    if (flags & TCL_TRACE_UNSETS) {
        if ((flags & TCL_TRACE_DESTROYED) && !(flags & TCL_INTERP_DESTROYED)) {
            Tcl_TraceVar2(interp, name1, name2,
                    TCL_GLOBAL_ONLY|TCL_TRACE_READS|TCL_TRACE_WRITES
                    |TCL_TRACE_UNSETS, TclPrecTraceProc, clientData);
        }
        return (char *) NULL;
    }

    /*
     * When the variable is read, reset its value from our shared
     * value.  This is needed in case the variable was modified in
     * some other interpreter so that this interpreter's value is
     * out of date.
     */

    if (flags & TCL_TRACE_READS) {
        Tcl_SetVar2(interp, name1, name2, precisionString,
                flags & TCL_GLOBAL_ONLY);
        return (char *) NULL;
    }

    /*
     * The variable is being written.  Check the new value and disallow
     * it if it isn't reasonable or if this is a safe interpreter (we
     * don't want safe interpreters messing up the precision of other
     * interpreters).
     */

    value = Tcl_GetVar2(interp, name1, name2, flags & TCL_GLOBAL_ONLY);
    if (value == NULL) {
        value = "";
    }
    prec = strtoul(value, &end, 10);
    if ((prec <= 0) || (prec > TCL_MAX_PREC) || (prec > 100) ||
            (end == value) || (*end != 0)) {
        Tcl_SetVar2(interp, name1, name2, precisionString,
                flags & TCL_GLOBAL_ONLY);
        return "improper value for precision";
    }
    TclFormatInt(precisionString, prec);
    sprintf(precisionFormat, "%%.%dg", prec);
    return (char *) NULL;
}


/*
 *----------------------------------------------------------------------
 *
 * TclNeedSpace --
 *
 *      This procedure checks to see whether it is appropriate to
 *      add a space before appending a new list element to an
 *      existing string.
 *
 * Results:
 *      The return value is 1 if a space is appropriate, 0 otherwise.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

int
TclNeedSpace(start, end)
    char *start;                /* First character in string. */
    char *end;                  /* End of string (place where space will
                                 * be added, if appropriate). */
{
    /*
     * A space is needed unless either
     * (a) we're at the start of the string, or
     * (b) the trailing characters of the string consist of one or more
     *     open curly braces preceded by a space or extending back to
     *     the beginning of the string.
     * (c) the trailing characters of the string consist of a space
     *     preceded by a character other than backslash.
     */

    if (end == start) {
        return 0;
    }
    end--;
    if (*end != '{') {
        if (isspace(UCHAR(*end)) && ((end == start) || (end[-1] != '\\'))) {
            return 0;
        }
        return 1;
    }
    do {
        if (end == start) {
            return 0;
        }
        end--;
    } while (*end == '{');
    if (isspace(UCHAR(*end))) {
        return 0;
    }
    return 1;
}


/*
 *----------------------------------------------------------------------
 *
 * TclFormatInt --
 *
 *      This procedure formats an integer into a sequence of decimal digit
 *      characters in a buffer. If the integer is negative, a minus sign is
 *      inserted at the start of the buffer. A null character is inserted at
 *      the end of the formatted characters. It is the caller's
 *      responsibility to ensure that enough storage is available. This
 *      procedure has the effect of sprintf(buffer, "%d", n) but is faster.
 *
 * Results:
 *      An integer representing the number of characters formatted, not
 *      including the terminating \0.
 *
 * Side effects:
 *      The formatted characters are written into the storage pointer to
 *      by the "buffer" argument.
 *
 *----------------------------------------------------------------------
 */

int
TclFormatInt(buffer, n)
    char *buffer;               /* Points to the storage into which the
                                 * formatted characters are written. */
    long n;                     /* The integer to format. */
{
    long intVal;
    int i;
    int numFormatted, j;
    char *digits = "0123456789";

    /*
     * Check first whether "n" is the maximum negative value. This is
     * -2^(m-1) for an m-bit word, and has no positive equivalent;
     * negating it produces the same value.
     */

    if (n == -n) {
        sprintf(buffer, "%ld", n);
        return strlen(buffer);
    }

    /*
     * Generate the characters of the result backwards in the buffer.
     */

    intVal = (n < 0? -n : n);
    i = 0;
    buffer[0] = '\0';
    do {
        i++;
        buffer[i] = digits[intVal % 10];
        intVal = intVal/10;
    } while (intVal > 0);
    if (n < 0) {
        i++;
        buffer[i] = '-';
    }
    numFormatted = i;

    /*
     * Now reverse the characters.
     */

    for (j = 0;  j < i;  j++, i--) {
        char tmp = buffer[i];
        buffer[i] = buffer[j];
        buffer[j] = tmp;
    }
    return numFormatted;
}


/*
 *----------------------------------------------------------------------
 *
 * TclLooksLikeInt --
 *
 *      This procedure decides whether the leading characters of a
 *      string look like an integer or something else (such as a
 *      floating-point number or string).
 *
 * Results:
 *      The return value is 1 if the leading characters of p look
 *      like a valid Tcl integer.  If they look like a floating-point
 *      number (e.g. "e01" or "2.4"), or if they don't look like a
 *      number at all, then 0 is returned.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

int
TclLooksLikeInt(p)
    char *p;                    /* Pointer to string. */
{
    while (isspace(UCHAR(*p))) {
        p++;
    }
    if ((*p == '+') || (*p == '-')) {
        p++;
    }
    if (!isdigit(UCHAR(*p))) {
        return 0;
    }
    p++;
    while (isdigit(UCHAR(*p))) {
        p++;
    }
    if ((*p != '.') && (*p != 'e') && (*p != 'E')) {
        return 1;
    }
    return 0;
}


/*
 *----------------------------------------------------------------------
 *
 * TclGetIntForIndex --
 *
 *      This procedure returns an integer corresponding to the list index
 *      held in a Tcl object. The Tcl object's value is expected to be
 *      either an integer or the string "end". 
 *
 * Results:
 *      The return value is normally TCL_OK, which means that the index was
 *      successfully stored into the location referenced by "indexPtr".  If
 *      the Tcl object referenced by "objPtr" has the value "end", the
 *      value stored is "endValue". If "objPtr"s values is not "end" and
 *      can not be converted to an integer, TCL_ERROR is returned and, if
 *      "interp" is non-NULL, an error message is left in the interpreter's
 *      result object.
 *
 * Side effects:
 *      The object referenced by "objPtr" might be converted to an
 *      integer object.
 *
 *----------------------------------------------------------------------
 */

int
TclGetIntForIndex(interp, objPtr, endValue, indexPtr)
     Tcl_Interp *interp;        /* Interpreter to use for error reporting. 
                                 * If NULL, then no error message is left
                                 * after errors. */
     Tcl_Obj *objPtr;           /* Points to an object containing either
                                 * "end" or an integer. */
     int endValue;              /* The value to be stored at "indexPtr" if
                                 * "objPtr" holds "end". */
     int *indexPtr;             /* Location filled in with an integer
                                 * representing an index. */
{
    Interp *iPtr = (Interp *) interp;
    char *bytes;
    int index, length, result;

    /*
     * THIS FAILS IF THE INDEX OBJECT'S STRING REP CONTAINS NULLS.
     */
    
    if (objPtr->typePtr == &tclIntType) {
        *indexPtr = (int)objPtr->internalRep.longValue;
        return TCL_OK;
    }
    
    bytes = TclGetStringFromObj(objPtr, &length);
    if ((*bytes == 'e')
            && (strncmp(bytes, "end", (unsigned) length) == 0)) {
        index = endValue;
    } else {
        result = Tcl_GetIntFromObj((Tcl_Interp *) NULL, objPtr, &index);
        if (result != TCL_OK) {
            if (iPtr != NULL) {
                Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
                        "bad index \"", bytes,
                        "\": must be integer or \"end\"", (char *) NULL);
            }
            return result;
        }
    }
    *indexPtr = index;
    return TCL_OK;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_GetNameOfExecutable --
 *
 *      This procedure simply returns a pointer to the internal full
 *      path name of the executable file as computed by
 *      Tcl_FindExecutable.  This procedure call is the C API
 *      equivalent to the "info nameofexecutable" command.
 *
 * Results:
 *      A pointer to the internal string or NULL if the internal full
 *      path name has not been computed or unknown.
 *
 * Side effects:
 *      The object referenced by "objPtr" might be converted to an
 *      integer object.
 *
 *----------------------------------------------------------------------
 */

CONST char *
Tcl_GetNameOfExecutable()
{
    return (tclExecutableName);
}