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/* $Id: pl-atom.c,v 1.24 1997/10/17 16:35:37 jan Exp $
Copyright (c) 1990 Jan Wielemaker. All rights reserved.
See ../LICENCE to find out about your rights.
jan@swi.psy.uva.nl
Purpose: atom management
*/
/*#define O_DEBUG 1*/
#include "pl-incl.h"
#include "pl-ctype.h"
static void rehashAtoms();
#define atom_buckets GD->atoms.buckets
#define atom_locked GD->atoms.locked
#define atomTable GD->atoms.table
#define lockAtoms() { atom_locked++; }
#define unlockAtoms() if ( --atom_locked == 0 && \
atom_buckets * 2 < GD->statistics.atoms ) \
rehashAtoms()
#if O_DEBUG
#define lookups GD->atoms.lookups
#define cmps GD->atoms.cmps
#endif
/*******************************
* BUILT-IN ATOM TABLE *
*******************************/
#define ATOM(s) s
typedef const char * ccharp;
static const ccharp atoms[] = {
#include "pl-atom.ic"
ATOM((char *)NULL)
};
#undef ATOM
static void
registerAtom(Atom a)
{ int n = entriesBuffer(&atom_array, Atom);
a->atom = (n<<LMASK_BITS)|TAG_ATOM;
addBuffer(&atom_array, a, Atom);
}
/*******************************
* GENERAL LOOKUP *
*******************************/
word
lookupAtom(const char *s)
{ int v0 = unboundStringHashValue(s);
int v = v0 & (atom_buckets-1);
Atom a;
DEBUG(0, lookups++);
for(a = atomTable[v]; a && !isTableRef(a); a = a->next)
{ DEBUG(0, cmps++);
if (streq(s, a->name) )
return a->atom;
}
a = (Atom)allocHeap(sizeof(struct atom));
a->next = atomTable[v];
#ifdef O_HASHTERM
a->hash_value = v0;
#endif
a->name = store_string(s);
atomTable[v] = a;
registerAtom(a);
GD->statistics.atoms++;
if ( atom_buckets * 2 < GD->statistics.atoms && !atom_locked )
rehashAtoms();
return a->atom;
}
/*******************************
* REHASH TABLE *
*******************************/
static void
makeAtomRefPointers()
{ Atom *a;
int n;
for(n=0, a=atomTable; n < (atom_buckets-1); n++, a++)
*a = makeTableRef(a+1);
*a = NULL;
}
static void
rehashAtoms()
{ Atom *oldtab = atomTable;
int oldbucks = atom_buckets;
Atom a, n;
startCritical;
atom_buckets *= 2;
atomTable = allocHeap(atom_buckets * sizeof(Atom));
makeAtomRefPointers();
DEBUG(0, Sdprintf("rehashing atoms (%d --> %d)\n", oldbucks, atom_buckets));
for(a=oldtab[0]; a; a = n)
{ int v;
while(isTableRef(a) )
{ a = unTableRef(Atom, a);
if ( a == NULL )
goto out;
}
n = a->next;
v = a->hash_value & (atom_buckets-1);
a->next = atomTable[v];
atomTable[v] = a;
}
out:
freeHeap(oldtab, oldbucks * sizeof(Atom));
endCritical;
}
word
pl_atom_hashstat(term_t idx, term_t n)
{ int i, m;
Atom a;
if ( !PL_get_integer(idx, &i) || i < 0 || i >= atom_buckets )
fail;
for(m = 0, a = atomTable[i]; a && !isTableRef(a); a = a->next)
m++;
return PL_unify_integer(n, m);
}
/* Note that the char * of the atoms is copied to the data segment. This
is done because some functions temporary change the char string associated
with an atom (pl_concat_atom()) and GCC puts char constants in the text
segment. Is this still true?
*/
static void
registerBuiltinAtoms()
{ int size = sizeof(atoms)/sizeof(char *) - 1;
Atom a = allocHeap(size * sizeof(struct atom));
const ccharp *s;
GD->statistics.atoms = size;
for(s = atoms; *s; s++, a++)
{ int v0 = unboundStringHashValue(*s);
int v = v0 & (atom_buckets-1);
a->name = (char *)*s;
#ifdef O_HASHTERM
a->hash_value = v0;
#endif
a->next = atomTable[v];
atomTable[v] = a;
registerAtom(a);
}
}
#if O_DEBUG
static void
exitAtoms(int status, void *arg)
{ Sdprintf("hashstat: %d lookupAtom() calls used %d strcmp() calls\n",
lookups, cmps);
}
#endif
void
initAtoms(void)
{ atom_buckets = ATOMHASHSIZE;
atomTable = allocHeap(atom_buckets * sizeof(Atom));
makeAtomRefPointers();
initBuffer(&atom_array);
registerBuiltinAtoms();
DEBUG(0, PL_on_halt(exitAtoms, NULL));
}
word
pl_current_atom(term_t a, word h)
{ Atom atom;
switch( ForeignControl(h) )
{ case FRG_FIRST_CALL:
if ( PL_is_atom(a) ) succeed;
if ( !PL_is_variable(a) ) fail;
atom = atomTable[0];
lockAtoms();
break;
case FRG_REDO:
atom = ForeignContextPtr(h);
break;
case FRG_CUTTED:
default:
unlockAtoms();
succeed;
}
while(atom && isTableRef(atom) )
atom = unTableRef(Atom, atom);
if ( atom )
{ PL_unify_atom(a, atom->atom);
return_next_table(Atom, atom, unlockAtoms());
}
unlockAtoms();
fail;
}
/*******************************
* ATOM COMPLETION *
*******************************/
#define ALT_SIZ 80 /* maximum length of one alternative */
#define ALT_MAX 256 /* maximum number of alternatives */
#define stringMatch(m) ((m)->name->name)
typedef struct match
{ Atom name;
int length;
} *Match;
static bool
allAlpha(register char *s)
{ for( ; *s; s++)
if ( !isAlpha(*s) )
fail;
succeed;
}
static int
extendAtom(char *prefix, bool *unique, char *common)
{ Atom a = atomTable[0];
bool first = TRUE;
int lp = (int) strlen(prefix);
*unique = TRUE;
for(; a; a = a->next)
{ while( isTableRef(a) )
{ a = unTableRef(Atom, a);
if ( !a )
goto out;
}
if ( strprefix(a->name, prefix) )
{ if ( strlen(a->name) >= LINESIZ )
continue;
if ( first == TRUE )
{ strcpy(common, a->name+lp);
first = FALSE;
} else
{ char *s = common;
char *q = a->name+lp;
while( *s && *s == *q )
s++, q++;
*s = EOS;
*unique = FALSE;
}
}
}
out:
return !first;
}
word
pl_complete_atom(term_t prefix, term_t common, term_t unique)
{ char *p;
bool u;
char buf[LINESIZ];
char cmm[LINESIZ];
if ( !PL_get_chars(prefix, &p, CVT_ALL) )
return warning("$complete_atom/3: instanstiation fault");
strcpy(buf, p);
if ( extendAtom(p, &u, cmm) )
{ strcat(buf, cmm);
if ( PL_unify_list_chars(common, buf) &&
PL_unify_atom(unique, u ? ATOM_unique : ATOM_not_unique) )
succeed;
}
fail;
}
static int
compareMatch(const void *m1, const void *m2)
{ return strcmp(stringMatch((Match)m1), stringMatch((Match)m2));
}
static bool
extend_alternatives(char *prefix, struct match *altv, int *altn)
{ Atom a = atomTable[0];
char *as;
int l;
*altn = 0;
for(; a; a=a->next)
{ while( a && isTableRef(a) )
a = unTableRef(Atom, a);
if ( a == (Atom) NULL )
break;
as = a->name;
if ( strprefix(as, prefix) &&
allAlpha(as) &&
(l = (int)strlen(as)) < ALT_SIZ )
{ Match m = &altv[(*altn)++];
m->name = a;
m->length = l;
if ( *altn > ALT_MAX )
break;
}
}
qsort(altv, *altn, sizeof(struct match), compareMatch);
succeed;
}
word
pl_atom_completions(term_t prefix, term_t alternatives)
{ char *p;
char buf[LINESIZ];
struct match altv[ALT_MAX];
int altn;
int i;
term_t alts = PL_copy_term_ref(alternatives);
term_t head = PL_new_term_ref();
if ( !PL_get_chars(prefix, &p, CVT_ALL) )
return warning("$atom_completions/2: instanstiation fault");
strcpy(buf, p);
extend_alternatives(buf, altv, &altn);
for(i=0; i<altn; i++)
{ if ( !PL_unify_list(alts, head, alts) ||
!PL_unify_atom(head, altv[i].name->atom) )
fail;
}
return PL_unify_nil(alts);
}
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Completeness generation for the GNU readline library. This function uses
a state variable to indicate the generator should maintain/reset its
state. Horrible! We use the thread-local structure to store the state,
so multiple Prolog threads can use this routine.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
char *
PL_atom_generator(char *prefix, int state)
{ Atom a;
if ( !state )
a = atomTable[0];
else
a = LD->atoms.generator;
for(; a; a=a->next)
{ char *as;
int l;
while( isTableRef(a) )
{ a = unTableRef(Atom, a);
if ( !a )
return NULL;
}
as = a->name;
if ( strprefix(as, prefix) &&
allAlpha(as) &&
(l = strlen(as)) < ALT_SIZ )
{ LD->atoms.generator = a->next;
return as;
}
}
return NULL;
}
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