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v0.5.1
v0.5.1
https://github.com/python/cpython
Revision d1e87a8288b18541ab555fc95ab94d06758015a0 authored by Tim Peters on 01 March 2001, 18:12:00 UTC, committed by Tim Peters on 01 March 2001, 18:12:00 UTC
of these "search the directory" schemes (including this one) are still prone to making mistakes.
1 parent 4f64c13
Tip revision: d1e87a8288b18541ab555fc95ab94d06758015a0 authored by Tim Peters on 01 March 2001, 18:12:00 UTC
More MacOSX fiddling. As noted in a comment, I believe all variations
More MacOSX fiddling. As noted in a comment, I believe all variations
Tip revision: d1e87a8
acceler.c
/* Parser accelerator module */
/* The parser as originally conceived had disappointing performance.
This module does some precomputation that speeds up the selection
of a DFA based upon a token, turning a search through an array
into a simple indexing operation. The parser now cannot work
without the accelerators installed. Note that the accelerators
are installed dynamically when the parser is initialized, they
are not part of the static data structure written on graminit.[ch]
by the parser generator. */
#include "pgenheaders.h"
#include "grammar.h"
#include "node.h"
#include "token.h"
#include "parser.h"
/* Forward references */
static void fixdfa(grammar *, dfa *);
static void fixstate(grammar *, state *);
void
PyGrammar_AddAccelerators(grammar *g)
{
dfa *d;
int i;
#ifdef Py_DEBUG
fprintf(stderr, "Adding parser accelerators ...\n");
#endif
d = g->g_dfa;
for (i = g->g_ndfas; --i >= 0; d++)
fixdfa(g, d);
g->g_accel = 1;
#ifdef Py_DEBUG
fprintf(stderr, "Done.\n");
#endif
}
void
PyGrammar_RemoveAccelerators(grammar *g)
{
dfa *d;
int i;
g->g_accel = 0;
d = g->g_dfa;
for (i = g->g_ndfas; --i >= 0; d++) {
state *s;
int j;
s = d->d_state;
for (j = 0; j < d->d_nstates; j++, s++) {
if (s->s_accel)
PyMem_DEL(s->s_accel);
s->s_accel = NULL;
}
}
}
static void
fixdfa(grammar *g, dfa *d)
{
state *s;
int j;
s = d->d_state;
for (j = 0; j < d->d_nstates; j++, s++)
fixstate(g, s);
}
static void
fixstate(grammar *g, state *s)
{
arc *a;
int k;
int *accel;
int nl = g->g_ll.ll_nlabels;
s->s_accept = 0;
accel = PyMem_NEW(int, nl);
for (k = 0; k < nl; k++)
accel[k] = -1;
a = s->s_arc;
for (k = s->s_narcs; --k >= 0; a++) {
int lbl = a->a_lbl;
label *l = &g->g_ll.ll_label[lbl];
int type = l->lb_type;
if (a->a_arrow >= (1 << 7)) {
printf("XXX too many states!\n");
continue;
}
if (ISNONTERMINAL(type)) {
dfa *d1 = PyGrammar_FindDFA(g, type);
int ibit;
if (type - NT_OFFSET >= (1 << 7)) {
printf("XXX too high nonterminal number!\n");
continue;
}
for (ibit = 0; ibit < g->g_ll.ll_nlabels; ibit++) {
if (testbit(d1->d_first, ibit)) {
#ifdef applec
#define MPW_881_BUG /* Undefine if bug below is fixed */
#endif
#ifdef MPW_881_BUG
/* In 881 mode MPW 3.1 has a code
generation bug which seems to
set the upper bits; fix this by
explicitly masking them off */
int temp;
#endif
if (accel[ibit] != -1)
printf("XXX ambiguity!\n");
#ifdef MPW_881_BUG
temp = 0xFFFF &
(a->a_arrow | (1 << 7) |
((type - NT_OFFSET) << 8));
accel[ibit] = temp;
#else
accel[ibit] = a->a_arrow | (1 << 7) |
((type - NT_OFFSET) << 8);
#endif
}
}
}
else if (lbl == EMPTY)
s->s_accept = 1;
else if (lbl >= 0 && lbl < nl)
accel[lbl] = a->a_arrow;
}
while (nl > 0 && accel[nl-1] == -1)
nl--;
for (k = 0; k < nl && accel[k] == -1;)
k++;
if (k < nl) {
int i;
s->s_accel = PyMem_NEW(int, nl-k);
if (s->s_accel == NULL) {
fprintf(stderr, "no mem to add parser accelerators\n");
exit(1);
}
s->s_lower = k;
s->s_upper = nl;
for (i = 0; k < nl; i++, k++)
s->s_accel[i] = accel[k];
}
PyMem_DEL(accel);
}
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