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/*
* tclStringRep.h --
*
* This file contains the definition of internal representations of a string
* and macros to access it.
*
* Conceptually, a string is a sequence of Unicode code points. Internally
* it may be stored in an encoding form such as a modified version of UTF-8
* or UTF-16 (when TCL_UTF_MAX=3) or UTF-32.
*
* Copyright (c) 1995-1997 Sun Microsystems, Inc.
* Copyright (c) 1999 by Scriptics Corporation.
*
* See the file "license.terms" for information on usage and redistribution of
* this file, and for a DISCLAIMER OF ALL WARRANTIES.
*/
#ifndef _TCLSTRINGREP
#define _TCLSTRINGREP
/*
* The following structure is the internal rep for a String object. It keeps
* track of how much memory has been used and how much has been allocated for
* the various representations to enable growing and shrinking of
* the String object with fewer mallocs. To optimize string
* length and indexing operations, this structure also stores the number of
* code points (independent of encoding form) once that value has been computed.
*/
typedef struct {
Tcl_Size numChars; /* The number of chars in the string.
* TCL_INDEX_NONE means this value has not been
* calculated. Any other means that there is a valid
* Unicode rep, or that the number of UTF bytes ==
* the number of chars. */
Tcl_Size allocated; /* The amount of space actually allocated for
* the UTF-8 string (minus 1 byte for the
* termination char). */
Tcl_Size maxChars; /* Max number of chars that can fit in the
* space allocated for the Unicode array. */
int hasUnicode; /* Boolean determining whether the string has
* a Tcl_UniChar representation. */
unsigned short unicode[TCLFLEXARRAY]; /* The array of Tcl_UniChar units.
* The actual size of this field depends on
* the maxChars field above. */
} String;
/* Limit on string lengths. The -1 because limit does not include the nul */
#define STRING_MAXCHARS \
(int)(((size_t)UINT_MAX - offsetof(String, unicode))/sizeof(unsigned short) - 1)
#define STRING_SIZE(numChars) \
(offsetof(String, unicode) + sizeof(unsigned short) + ((numChars) * sizeof(unsigned short)))
#define stringCheckLimits(numChars) \
do { \
if ((numChars) < 0 || (numChars) > STRING_MAXCHARS) { \
Tcl_Panic("max length for a Tcl unicode value (%d chars) exceeded", \
STRING_MAXCHARS); \
} \
} while (0)
#define stringAttemptAlloc(numChars) \
(String *) attemptckalloc(STRING_SIZE(numChars))
#define stringAlloc(numChars) \
(String *) ckalloc(STRING_SIZE(numChars))
#define stringRealloc(ptr, numChars) \
(String *) ckrealloc((ptr), STRING_SIZE(numChars))
#define stringAttemptRealloc(ptr, numChars) \
(String *) attemptckrealloc((ptr), STRING_SIZE(numChars))
#define GET_STRING(objPtr) \
((String *) (objPtr)->internalRep.twoPtrValue.ptr1)
#define SET_STRING(objPtr, stringPtr) \
((objPtr)->internalRep.twoPtrValue.ptr2 = NULL), \
((objPtr)->internalRep.twoPtrValue.ptr1 = (void *) (stringPtr))
#endif /* _TCLSTRINGREP */
/*
* Local Variables:
* mode: c
* c-basic-offset: 4
* fill-column: 78
* End:
*/
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