automata.c revision 4fd606d1f5abe38e1f42c38de1d2e895166bd0f4
2N/A/* Automata conversion functions for DLG
2N/A *
2N/A * SOFTWARE RIGHTS
2N/A *
2N/A * We reserve no LEGAL rights to the Purdue Compiler Construction Tool
2N/A * Set (PCCTS) -- PCCTS is in the public domain. An individual or
2N/A * company may do whatever they wish with source code distributed with
2N/A * PCCTS or the code generated by PCCTS, including the incorporation of
2N/A * PCCTS, or its output, into commerical software.
2N/A *
2N/A * We encourage users to develop software with PCCTS. However, we do ask
2N/A * that credit is given to us for developing PCCTS. By "credit",
2N/A * we mean that if you incorporate our source code into one of your
2N/A * programs (commercial product, research project, or otherwise) that you
2N/A * acknowledge this fact somewhere in the documentation, research report,
2N/A * etc... If you like PCCTS and have developed a nice tool with the
2N/A * output, please mention that you developed it using PCCTS. In
2N/A * addition, we ask that this header remain intact in our source code.
2N/A * As long as these guidelines are kept, we expect to continue enhancing
2N/A * this system and expect to make other tools available as they are
2N/A * completed.
2N/A *
2N/A * DLG 1.33
2N/A * Will Cohen
2N/A * With mods by Terence Parr; AHPCRC, University of Minnesota
2N/A * 1989-2001
2N/A */
2N/A
2N/A#include <stdio.h>
2N/A#include "pcctscfg.h"
#include "dlg.h"
#ifdef MEMCHK
#include "trax.h"
#else
#ifdef __STDC__
#include <stdlib.h>
#else
#include <malloc.h>
#endif /* __STDC__ */
#endif
#define hash_list struct _hash_list_
hash_list{
hash_list *next; /* next thing in list */
dfa_node *node;
};
int dfa_allocated = 0; /* keeps track of number of dfa nodes */
dfa_node **dfa_array; /* root of binary tree that stores dfa array */
dfa_node *dfa_model_node;
hash_list *dfa_hash[HASH_SIZE]; /* used to quickly find */
/* desired dfa node */
void
#ifdef __USE_PROTOS
make_dfa_model_node(int width)
#else
make_dfa_model_node(width)
int width;
#endif
{
register int i;
dfa_model_node = (dfa_node*) malloc(sizeof(dfa_node)
+ sizeof(int)*width);
dfa_model_node->node_no = -1; /* impossible value for real dfa node */
dfa_model_node->dfa_set = 0;
dfa_model_node->alternatives = FALSE;
dfa_model_node->done = FALSE;
dfa_model_node->nfa_states = empty;
for(i = 0; i<width; i++){
dfa_model_node->trans[i] = NIL_INDEX;
}
}
/* adds a new nfa to the binary tree and returns a pointer to it */
dfa_node *
#ifdef __USE_PROTOS
new_dfa_node(set nfa_states)
#else
new_dfa_node(nfa_states)
set nfa_states;
#endif
{
register int j;
register dfa_node *t;
static int dfa_size=0; /* elements dfa_array[] can hold */
++dfa_allocated;
if (dfa_size<=dfa_allocated){
/* need to redo array */
if (!dfa_array){
/* need some to do inital allocation */
dfa_size=dfa_allocated+DFA_MIN;
dfa_array=(dfa_node **) malloc(sizeof(dfa_node*)*
dfa_size);
}else{
/* need more space */
dfa_size=2*(dfa_allocated+1);
dfa_array=(dfa_node **) realloc(dfa_array,
sizeof(dfa_node*)*dfa_size);
}
}
/* fill out entry in array */
t = (dfa_node*) malloc(sizeof(nfa_node)+sizeof(int)*class_no);
*t = *dfa_model_node;
for (j=0; j<class_no; ++j)
t->trans[j] = NIL_INDEX;
t->node_no = dfa_allocated;
t->nfa_states = set_dup(nfa_states);
dfa_array[dfa_allocated] = t;
return t;
}
/* past a pointer to the start start of the nfa graph
* nfa_to_dfa convers this graph to dfa. The function returns
* a pointer to the first dfa state.
* NOTE: The function that prints out the table will have to figure out how
* to find the other dfa states given the first dfa_state and the number of dfa
* nodes allocated
*/
dfa_node **
#ifdef __USE_PROTOS
nfa_to_dfa(nfa_node *start)
#else
nfa_to_dfa(start)
nfa_node *start;
#endif
{
register dfa_node *d_state, *trans_d_state;
register int a;
set t;
int last_done;
unsigned *nfa_list;
unsigned *reach_list;
reach_list = (unsigned *) malloc((2+nfa_allocated)*sizeof(unsigned));
if (!start) return NULL;
t = set_of(NFA_NO(start));
_set_pdq(t,reach_list);
closure(&t,reach_list);
/* Make t a dfa state */
d_state = dfastate(t);
last_done = DFA_NO(d_state);
do {
/* Mark dfa state x as "done" */
d_state->done = TRUE;
nfa_list = set_pdq(d_state->nfa_states);
for (a = 0; a<class_no; ++a) {
/* Add NFA states reached by a from d_state */
reach(nfa_list,a,reach_list);
/* Were any states found? */
if ((*reach_list)!=nil) {
/* was t=empty; */
set_free(t);
/* yes, compute closure */
closure(&t,reach_list);
/* Make DFA state of it ... */
trans_d_state = dfastate(t);
/* And make transition x->t, labeled with a */
d_state->trans[a] = DFA_NO(trans_d_state);
d_state->alternatives = TRUE;
}
}
free(nfa_list);
++last_done; /* move forward in queue */
/* And so forth until nothing isn't done */
d_state = DFA(last_done);
} while (last_done<=dfa_allocated);
free(reach_list);
set_free(t);
/* returns pointer to the array that holds the automaton */
return dfa_array;
}
void
#ifdef __USE_PROTOS
clear_hash(void)
#else
clear_hash()
#endif
{
register int i;
for(i=0; i<HASH_SIZE; ++i)
dfa_hash[i] = 0;
}
#if HASH_STAT
void
#ifdef __USE_PROTOS
fprint_hash_stats(FILE *f)
#else
fprint_hash_stats(f)
FILE *f;
#endif
{
register hash_list *p;
register int i,j;
register total;
total=0;
for(i=0; i<HASH_SIZE; ++i){
j=0;
p = dfa_hash[i];
while(p){
++j;
p = p->next;
}
total+=j;
fprintf(f,"bin[%d] has %d\n",i,j);
}
fprintf(f,"total = %d\n",total);
}
#endif
/* Returns a pointer to a dfa node that has the same nfa nodes in it.
* This may or maynot be a newly created node.
*/
dfa_node *
#ifdef __USE_PROTOS
dfastate(set nfa_states)
#else
dfastate(nfa_states)
set nfa_states;
#endif
{
register hash_list *p;
int bin;
/* hash using set and see if it exists */
bin = set_hash(nfa_states,HASH_SIZE);
p = dfa_hash[bin];
while(p && !set_equ(nfa_states,(p->node)->nfa_states)){
p = p->next;
}
if(!p){
/* next state to add to hash table */
p = (hash_list*)malloc(sizeof(hash_list));
p->node = new_dfa_node(nfa_states);
p->next = dfa_hash[bin];
dfa_hash[bin] = p;
}
return (p->node);
}
/* this reach assumes the closure has been done already on set */
int
#ifdef __USE_PROTOS
reach(unsigned *nfa_list, register int a, unsigned *reach_list)
#else
reach(nfa_list, a, reach_list)
unsigned *nfa_list;
register int a;
unsigned *reach_list;
#endif
{
register unsigned *e;
register nfa_node *node;
int t=0;
e = nfa_list;
if (e){
while (*e != nil){
node = NFA(*e);
if (set_el(a,node->label)){
t=1;
*reach_list=NFA_NO(node->trans[0]);
++reach_list;
}
++e;
}
}
*reach_list=nil;
return t;
}
/* finds all the nodes that can be reached by epsilon transitions
from the set of a nodes and returns puts them back in set b */
set
#ifdef __USE_PROTOS
closure(set *b, unsigned *reach_list)
#else
closure(b, reach_list)
set *b;
unsigned *reach_list;
#endif
{
register nfa_node *node,*n; /* current node being examined */
register unsigned *e;
++operation_no;
#if 0
t = e = set_pdq(*b);
#else
e=reach_list;
#endif
while (*e != nil){
node = NFA(*e);
set_orel(NFA_NO(node),b);
/* mark it done */
node->nfa_set = operation_no;
if ((n=node->trans[0]) != NIL_INDEX && set_nil(node->label) &&
(n->nfa_set != operation_no)){
/* put in b */
set_orel(NFA_NO(n),b);
close1(n,operation_no,b);
}
if ((n=node->trans[1]) != NIL_INDEX &&
(n->nfa_set != operation_no)){
/* put in b */
set_orel(NFA_NO(node->trans[1]),b);
close1(n,operation_no,b);
}
++e;
}
#if 0
free(t);
#endif
return *b;
}
#ifdef __USE_PROTOS
void close1(nfa_node *node, int o, set *b)
#else
void close1(node,o,b)
nfa_node *node;
int o; /* marker to avoid cycles */
set *b;
#endif
{
register nfa_node *n; /* current node being examined */
/* mark it done */
node->nfa_set = o;
if ((n=node->trans[0]) != NIL_INDEX && set_nil(node->label) &&
(n->nfa_set != o)){
/* put in b */
set_orel(NFA_NO(n),b);
close1(n,o,b);
}
if ((n=node->trans[1]) != NIL_INDEX &&
(n->nfa_set != o)){
/* put in b */
set_orel(NFA_NO(node->trans[1]),b);
close1(n,o,b);
}
}