stk/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.
 *
 *  SCCS: @(#) tclUtil.c 1.2 98/06/12 16:49:08
 */

#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.
 */
#ifndef SCM_CODE
static char precisionString[10] = "12";
				/* The string value of all the tcl_precision
				 * variables. */
#endif
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;
    }

#ifdef SCM_CODE
    if (*p == '(') {
#else
    if (*p == '{') {
#endif
	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.
	     */

#ifdef SCM_CODE
	    case '(':
#else
	    case '{':
#endif
		if (openBraces != 0) {
		    openBraces++;
		}
		break;

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

#ifdef SCM_CODE
	    case ')':
#else
	    case '}':
#endif
		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.
     */

#ifdef SCM_CODE
    {
      char *q;

      for (size = 1, p = q = list; *p != 0; p++) {
	if (isspace(UCHAR(*p))) size++;
	if (*p == ')') q = p; 
      }

      /* 
       * Tcl considers strings of the form "( ... )" as quoted string
       * (rather than lists). So if the string is of this form, open
       * and close parenthesis are replaced by spaces
       */
      if (q > list && *list == '(' && *q == ')') {
	*list = *q = ' ';
      }
    }
#else
    for (size = 1, p = list; *p != 0; p++) {
	if (isspace(UCHAR(*p))) {
	    size++;
	}
    }
#endif
    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;
#ifdef SCM_CODE
    flags = TCL_DONT_USE_BRACES;
#else
    flags = 0;
#endif
    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;
#ifndef SCM_CODE
	    case '[':
	    case '$':
	    case ';':
	    case ' ':
	    case '\f':
	    case '\n':
	    case '\r':
	    case '\t':
	    case '\v':
		flags |= USE_BRACES;
		break;
#endif
	    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;
#ifndef SCM_CODE
    CONST char *lastChar;
#endif

    /*
     * 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);
    }
#ifdef SCM_CODE
    if ((src == NULL) || (*src == 0)) {
        p[0] = '\\';
 	p[1] = '0';
 	p[2] = 0;
 	return 2;
    }
    while ((*p++ = *src++)) /* Nothing */;
    return p - dst - 1;
#else
    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;
#endif
}

/*
 *----------------------------------------------------------------------
 *
 * 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;