refstr.c

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/* $Id$ $Revision$ */
/* vim:set shiftwidth=4 ts=8: */

/*************************************************************************
 * Copyright (c) 2011 AT&T Intellectual Property 
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors: See CVS logs. Details at http://www.graphviz.org/
 *************************************************************************/

#include <cghdr.h>

#ifdef DMALLOC
#include "dmalloc.h"
#endif

/*
 * reference counted strings.
 */

static uint64_t HTML_BIT;       /* msbit of uint64_t */
static uint64_t CNT_BITS;       /* complement of HTML_BIT */

typedef struct refstr_t {
    Dtlink_t link;
    uint64_t refcnt;
    char *s;
    char store[1];              /* this is actually a dynamic array */
} refstr_t;

static Dtdisc_t Refstrdisc = {
    offsetof(refstr_t, s),      /* key */
    -1,                         /* size */
    0,                          /* link offset */
    NIL(Dtmake_f),
    agdictobjfree,
    NIL(Dtcompar_f),
    NIL(Dthash_f),
    agdictobjmem,
    NIL(Dtevent_f)
};

static Dict_t *Refdict_default;

/* refdict:
 * Return the string dictionary associated with g.
 * If necessary, create it.
 * As a side-effect, set html masks. This assumes 8-bit bytes.
 */
static Dict_t *refdict(Agraph_t * g)
{
    Dict_t **dictref;

    if (g)
        dictref = &(g->clos->strdict);
    else
        dictref = &Refdict_default;
    if (*dictref == NIL(Dict_t *)) {
        *dictref = agdtopen(g, &Refstrdisc, Dttree);
        HTML_BIT = ((unsigned int) 1) << (sizeof(unsigned int) * 8 - 1);
        CNT_BITS = ~HTML_BIT;
    }
    return *dictref;
}

int agstrclose(Agraph_t * g)
{
    return agdtclose(g, refdict(g));
}

static refstr_t *refsymbind(Dict_t * strdict, char *s)
{
    refstr_t key, *r;
    key.s = s;
    r = (refstr_t *) dtsearch(strdict, &key);
    return r;
}

static char *refstrbind(Dict_t * strdict, char *s)
{
    refstr_t *r;
    r = refsymbind(strdict, s);
    if (r)
        return r->s;
    else
        return NIL(char *);
}

char *agstrbind(Agraph_t * g, char *s)
{
    return refstrbind(refdict(g), s);
}

char *agstrdup(Agraph_t * g, char *s)
{
    refstr_t *r;
    Dict_t *strdict;
    size_t sz;

    if (s == NIL(char *))
         return NIL(char *);
    strdict = refdict(g);
    r = refsymbind(strdict, s);
    if (r)
        r->refcnt++;
    else {
        sz = sizeof(refstr_t) + strlen(s);
        if (g)
            r = (refstr_t *) agalloc(g, sz);
        else
            r = (refstr_t *) malloc(sz);
        r->refcnt = 1;
        strcpy(r->store, s);
        r->s = r->store;
        dtinsert(strdict, r);
    }
    return r->s;
}

char *agstrdup_html(Agraph_t * g, char *s)
{
    refstr_t *r;
    Dict_t *strdict;
    size_t sz;

    if (s == NIL(char *))
         return NIL(char *);
    strdict = refdict(g);
    r = refsymbind(strdict, s);
    if (r)
        r->refcnt++;
    else {
        sz = sizeof(refstr_t) + strlen(s);
        if (g)
            r = (refstr_t *) agalloc(g, sz);
        else
            r = (refstr_t *) malloc(sz);
        r->refcnt = 1 | HTML_BIT;
        strcpy(r->store, s);
        r->s = r->store;
        dtinsert(strdict, r);
    }
    return r->s;
}

int agstrfree(Agraph_t * g, char *s)
{
    refstr_t *r;
    Dict_t *strdict;

    if (s == NIL(char *))
         return FAILURE;

    strdict = refdict(g);
    r = refsymbind(strdict, s);
    if (r && (r->s == s)) {
        r->refcnt--;
        if ((r->refcnt && CNT_BITS) == 0) {
            agdtdelete(g, strdict, r);
            /*
               if (g) agfree(g,r);
               else free(r);
             */
        }
    }
    if (r == NIL(refstr_t *))
        return FAILURE;
    return SUCCESS;
}

/* aghtmlstr:
 * Return true if s is an HTML string.
 * We assume s points to the datafield store[0] of a refstr.
 */
int aghtmlstr(char *s)
{
    refstr_t *key;

    if (s == NULL)
        return 0;
    key = (refstr_t *) (s - offsetof(refstr_t, store[0]));
    return (key->refcnt & HTML_BIT);
}

void agmarkhtmlstr(char *s)
{
    refstr_t *key;

    if (s == NULL)
        return;
    key = (refstr_t *) (s - offsetof(refstr_t, store[0]));
    key->refcnt |= HTML_BIT;
}

#ifdef DEBUG
static int refstrprint(Dict_t * dict, void *ptr, void *user)
{
    refstr_t *r;

    NOTUSED(dict);
    r = ptr;
    NOTUSED(user);
    write(2, r->s, strlen(r->s));
    write(2, "\n", 1);
    return 0;
}

void agrefstrdump(Agraph_t * g)
{
    dtwalk(Refdict_default, refstrprint, 0);
}
#endif