libxkbcommon/src/atom.c

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Copyright 1987 by Digital Equipment Corporation, Maynard, Massachusetts.

                        All Rights Reserved

Permission to use, copy, modify, and distribute this software and its
documentation for any purpose and without fee is hereby granted,
provided that the above copyright notice appear in all copies and that
both that copyright notice and this permission notice appear in
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/************************************************************
 Copyright 1994 by Silicon Graphics Computer Systems, Inc.

 Permission to use, copy, modify, and distribute this
 software and its documentation for any purpose and without
 fee is hereby granted, provided that the above copyright
 notice appear in all copies and that both that copyright
 notice and this permission notice appear in supporting
 documentation, and that the name of Silicon Graphics not be
 used in advertising or publicity pertaining to distribution
 of the software without specific prior written permission.
 Silicon Graphics makes no representation about the suitability
 of this software for any purpose. It is provided "as is"
 without any express or implied warranty.

 SILICON GRAPHICS DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
 SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON
 GRAPHICS BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
 DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION  WITH
 THE USE OR PERFORMANCE OF THIS SOFTWARE.

 ********************************************************/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "X11/extensions/XKBcommon.h"
#include "XKBcommonint.h"

#define InitialTableSize 100

typedef struct _Node {
    struct _Node    *left, *right;
    Atom            a;
    unsigned int    fingerPrint;
    char            *string;
} NodeRec, *NodePtr;

#define BAD_RESOURCE 0xe0000000

static Atom lastAtom = None;
static NodePtr atomRoot = NULL;
static unsigned long tableLength;
static NodePtr *nodeTable = NULL;

void
XkbcInitAtoms(void)
{
    if (nodeTable)
        return;

    tableLength = InitialTableSize;
    nodeTable = (NodePtr *)_XkbAlloc(InitialTableSize * sizeof(NodePtr));
    nodeTable[None] = NULL;
}

char *
XkbcAtomGetString(Atom atom)
{
    NodePtr node;

    if ((atom == None) || (atom > lastAtom))
        return NULL;
    if (!(node = nodeTable[atom]))
        return NULL;
    return strdup(node->string);
}

static Atom
_XkbcMakeAtom(char *string, unsigned len, Bool makeit)
{
    NodePtr *np;
    unsigned i;
    int comp;
    unsigned int fp = 0;

    np = &atomRoot;
    for (i = 0; i < (len + 1) / 2; i++) {
        fp = fp * 27 + string[i];
        fp = fp * 27 + string[len - 1 - i];
    }

    while (*np) {
        if (fp < (*np)->fingerPrint)
            np = &((*np)->left);
        else if (fp > (*np)->fingerPrint)
            np = &((*np)->right);
        else {
            /* now start testing the strings */
            comp = strncmp(string, (*np)->string, (int)len);
            if ((comp < 0) || ((comp == 0) && (len < strlen((*np)->string))))
                np = &((*np)->left);
            else if (comp > 0)
                np = &((*np)->right);
            else
                return(*np)->a;
            }
    }

    if (makeit) {
        NodePtr nd;

        nd = (NodePtr)_XkbAlloc(sizeof(NodeRec));
        if (!nd)
            return BAD_RESOURCE;

        nd->string = (char *)_XkbAlloc(len + 1);
        if (!nd->string) {
            _XkbFree(nd);
            return BAD_RESOURCE;
        }
        strncpy(nd->string, string, (int)len);
        nd->string[len] = 0;

        if ((lastAtom + 1) >= tableLength) {
            NodePtr *table;

            table = (NodePtr *)_XkbRealloc(nodeTable,
                                           tableLength * 2 * sizeof(NodePtr));
            if (!table) {
                if (nd->string != string)
                    _XkbFree(nd->string);
                _XkbFree(nd);
                return BAD_RESOURCE;
            }
            tableLength <<= 1;

            nodeTable = table;
        }

        *np = nd;
        nd->left = nd->right = NULL;
        nd->fingerPrint = fp;
        nd->a = (++lastAtom);
        *(nodeTable + lastAtom) = nd;

        return nd->a;
    }
    else
        return None;
}

Atom
XkbcInternAtom(char *name, Bool onlyIfExists)
{
    if (!name)
        return None;
    return _XkbcMakeAtom(name, strlen(name), !onlyIfExists);
}