htatom.c

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/*			Atoms: Names to numbers			HTAtom.c
**			=======================
**
**	Atoms are names which are given representative pointer values
**	so that they can be stored more efficiently, and comparisons
**	for equality done more efficiently.
**
**	Atoms are kept in a hash table consisting of an array of linked lists.
**
** Authors:
**	TBL	Tim Berners-Lee, WorldWideWeb project, CERN
**	(c) Copyright CERN 1991 - See Copyright.html
**
*/

#include <HTUtils.h>

#define HASH_SIZE	101		/* Tunable */
#include <HTAtom.h>

#include <HTList.h>

#include <LYexit.h>
#include <LYLeaks.h>

PRIVATE HTAtom * hash_table[HASH_SIZE];
PRIVATE BOOL initialised = NO;

/*
 *	To free off all atoms.
 */
#ifdef LY_FIND_LEAKS
PRIVATE void free_atoms NOPARAMS;
#endif

/*
 *	Alternate hashing function.
 */
#define HASH_FUNCTION(cp_hash) ((strlen(cp_hash) * UCH(*cp_hash)) % HASH_SIZE)

PUBLIC HTAtom * HTAtom_for ARGS1(CONST char *, string)
{
    int hash;
    HTAtom * a;

    /*		First time around, clear hash table
    */
    /*
     *	Memory leak fixed.
     *  05-29-94 Lynx 2-3-1 Garrett Arch Blythe
     */
    if (!initialised) {
	int i;
	for (i = 0; i < HASH_SIZE; i++)
	    hash_table[i] = (HTAtom *) 0;
	initialised = YES;
#ifdef LY_FIND_LEAKS
	atexit(free_atoms);
#endif
    }

    /*		Generate hash function
    */
    hash = HASH_FUNCTION(string);

    /*		Search for the string in the list
    */
    for (a = hash_table[hash]; a; a = a->next) {
	if (0 == strcasecomp(a->name, string)) {
	    /* CTRACE((tfp, "HTAtom: Old atom %p for `%s'\n", a, string)); */
	    return a;				/* Found: return it */
	}
    }

    /*		Generate a new entry
    */
    a = (HTAtom *)malloc(sizeof(*a));
    if (a == NULL)
	outofmem(__FILE__, "HTAtom_for");
    a->name = (char *)malloc(strlen(string)+1);
    if (a->name == NULL)
	outofmem(__FILE__, "HTAtom_for");
    strcpy(a->name, string);
    a->next = hash_table[hash];		/* Put onto the head of list */
    hash_table[hash] = a;
#ifdef NOT_DEFINED
    CTRACE((tfp, "HTAtom: New atom %p for `%s'\n", a, string));
#endif /* NOT_DEFINED */
    return a;
}

#ifdef LY_FIND_LEAKS
/*
 *	Purpose:	Free off all atoms.
 *	Arguments:	void
 *	Return Value:	void
 *	Remarks/Portability/Dependencies/Restrictions:
 *		To be used at program exit.
 *	Revision History:
 *		05-29-94	created Lynx 2-3-1 Garrett Arch Blythe
 */
PRIVATE void free_atoms NOARGS
{
	auto int i_counter;
	HTAtom *HTAp_freeme;
	/*
	 *	Loop through all lists of atoms.
	 */
	for (i_counter = 0; i_counter < HASH_SIZE; i_counter++)	{
		/*
		 *	Loop through the list.
		 */
		while (hash_table[i_counter] != NULL)	{
			/*
			 *	Free off atoms and any members.
			 */
			HTAp_freeme = hash_table[i_counter];
			hash_table[i_counter] = HTAp_freeme->next;
			FREE(HTAp_freeme->name);
			FREE(HTAp_freeme);
		}
	}
}
#endif /* LY_FIND_LEAKS */

PRIVATE BOOL mime_match ARGS2(CONST char *, name,
			      CONST char *, templ)
{
    if (name && templ) {
	static char *n1 = NULL;
	static char *t1 = NULL;
	char *n2;
	char *t2;

	StrAllocCopy(n1, name);		/* These also free the ones	*/
	StrAllocCopy(t1, templ);	/* from previous call.		*/

	if (!(n2 = strchr(n1, '/'))  ||  !(t2 = strchr(t1, '/')))
	    return NO;

	*(n2++) = (char)0;
	*(t2++) = (char)0;

	if ((0 == strcmp(t1, "*") || 0 == strcmp(t1, n1)) &&
	    (0 == strcmp(t2, "*") || 0 == strcmp(t2, n2)))
	    return YES;
    }
    return NO;
}


PUBLIC HTList *HTAtom_templateMatches ARGS1(CONST char *, templ)
{
    HTList *matches = HTList_new();

    if (initialised && templ) {
	int i;
	HTAtom *cur;

	for (i = 0; i < HASH_SIZE; i++) {
	    for (cur = hash_table[i];  cur;  cur = cur->next) {
		if (mime_match(cur->name, templ))
		    HTList_addObject(matches, (void*)cur);
	    }
	}
    }
    return matches;
}