/* Compute look-ahead criteria for bison,
- Copyright (C) 1984, 1986, 1989 Free Software Foundation, Inc.
+ Copyright (C) 1984, 1986, 1989, 2000 Free Software Foundation, Inc.
-This file is part of Bison, the GNU Compiler Compiler.
+ This file is part of Bison, the GNU Compiler Compiler.
-Bison is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2, or (at your option)
-any later version.
+ Bison is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
-Bison is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-GNU General Public License for more details.
+ Bison is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
-You should have received a copy of the GNU General Public License
-along with Bison; see the file COPYING. If not, write to
-the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-Boston, MA 02111-1307, USA. */
+ You should have received a copy of the GNU General Public License
+ along with Bison; see the file COPYING. If not, write to
+ the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
-/* Compute how to make the finite state machine deterministic;
- find which rules need lookahead in each state, and which lookahead tokens they accept.
-
-lalr(), the entry point, builds these data structures:
-
-goto_map, from_state and to_state
- record each shift transition which accepts a variable (a nonterminal).
-ngotos is the number of such transitions.
-from_state[t] is the state number which a transition leads from
-and to_state[t] is the state number it leads to.
-All the transitions that accept a particular variable are grouped together and
-goto_map[i - ntokens] is the index in from_state and to_state of the first of them.
-
-consistent[s] is nonzero if no lookahead is needed to decide what to do in state s.
-
-LAruleno is a vector which records the rules that need lookahead in various states.
-The elements of LAruleno that apply to state s are those from
- lookaheads[s] through lookaheads[s+1]-1.
-Each element of LAruleno is a rule number.
-
-If lr is the length of LAruleno, then a number from 0 to lr-1
-can specify both a rule and a state where the rule might be applied.
-
-LA is a lr by ntokens matrix of bits.
-LA[l, i] is 1 if the rule LAruleno[l] is applicable in the appropriate state
- when the next token is symbol i.
-If LA[l, i] and LA[l, j] are both 1 for i != j, it is a conflict.
-*/
+/* Compute how to make the finite state machine deterministic; find
+ which rules need lookahead in each state, and which lookahead
+ tokens they accept. */
#include "system.h"
#include "types.h"
-#include "state.h"
+#include "LR0.h"
#include "alloc.h"
#include "gram.h"
#include "complain.h"
-
-extern short **derives;
-extern char *nullable;
-
+#include "lalr.h"
+#include "nullable.h"
+#include "derives.h"
int tokensetsize;
short *lookaheads;
short *from_state;
short *to_state;
-extern void lalr PARAMS((void));
-
-static short **transpose PARAMS((short **, int));
-static void set_state_table PARAMS((void));
-static void set_accessing_symbol PARAMS((void));
-static void set_shift_table PARAMS((void));
-static void set_reduction_table PARAMS((void));
-static void set_maxrhs PARAMS((void));
-static void initialize_LA PARAMS((void));
-static void set_goto_map PARAMS((void));
-static int map_goto PARAMS((int, int));
-static void initialize_F PARAMS((void));
-static void build_relations PARAMS((void));
-static void add_lookback_edge PARAMS((int, int, int));
-static void compute_FOLLOWS PARAMS((void));
-static void compute_lookaheads PARAMS((void));
-static void digraph PARAMS((short **));
-static void traverse PARAMS((register int));
-
-extern void berror PARAMS((const char *));
+extern void berror PARAMS ((const char *));
static int infinity;
static int maxrhs;
static int top;
-void
-lalr (void)
+static void
+traverse (int i)
{
- tokensetsize = WORDSIZE(ntokens);
-
- set_state_table();
- set_accessing_symbol();
- set_shift_table();
- set_reduction_table();
- set_maxrhs();
- initialize_LA();
- set_goto_map();
- initialize_F();
- build_relations();
- compute_FOLLOWS();
- compute_lookaheads();
+ unsigned *fp1;
+ unsigned *fp2;
+ unsigned *fp3;
+ int j;
+ short *rp;
+
+ int height;
+ unsigned *base;
+
+ VERTICES[++top] = i;
+ INDEX[i] = height = top;
+
+ base = F + i * tokensetsize;
+ fp3 = base + tokensetsize;
+
+ rp = R[i];
+ if (rp)
+ {
+ while ((j = *rp++) >= 0)
+ {
+ if (INDEX[j] == 0)
+ traverse (j);
+
+ if (INDEX[i] > INDEX[j])
+ INDEX[i] = INDEX[j];
+
+ fp1 = base;
+ fp2 = F + j * tokensetsize;
+
+ while (fp1 < fp3)
+ *fp1++ |= *fp2++;
+ }
+ }
+
+ if (INDEX[i] == height)
+ {
+ for (;;)
+ {
+ j = VERTICES[top--];
+ INDEX[j] = infinity;
+
+ if (i == j)
+ break;
+
+ fp1 = base;
+ fp2 = F + j * tokensetsize;
+
+ while (fp1 < fp3)
+ *fp2++ = *fp1++;
+ }
+ }
}
+static void
+digraph (short **relation)
+{
+ int i;
+
+ infinity = ngotos + 2;
+ INDEX = NEW2 (ngotos + 1, short);
+ VERTICES = NEW2 (ngotos + 1, short);
+ top = 0;
+
+ R = relation;
+
+ for (i = 0; i < ngotos; i++)
+ INDEX[i] = 0;
+
+ for (i = 0; i < ngotos; i++)
+ {
+ if (INDEX[i] == 0 && R[i])
+ traverse (i);
+ }
+
+ FREE (INDEX);
+ FREE (VERTICES);
+}
+
static void
set_state_table (void)
{
- register core *sp;
+ core *sp;
- state_table = NEW2(nstates, core *);
+ state_table = NEW2 (nstates, core *);
for (sp = first_state; sp; sp = sp->next)
state_table[sp->number] = sp;
static void
set_accessing_symbol (void)
{
- register core *sp;
+ core *sp;
- accessing_symbol = NEW2(nstates, short);
+ accessing_symbol = NEW2 (nstates, short);
for (sp = first_state; sp; sp = sp->next)
accessing_symbol[sp->number] = sp->accessing_symbol;
static void
set_shift_table (void)
{
- register shifts *sp;
+ shifts *sp;
- shift_table = NEW2(nstates, shifts *);
+ shift_table = NEW2 (nstates, shifts *);
for (sp = first_shift; sp; sp = sp->next)
shift_table[sp->number] = sp;
static void
set_reduction_table (void)
{
- register reductions *rp;
+ reductions *rp;
- reduction_table = NEW2(nstates, reductions *);
+ reduction_table = NEW2 (nstates, reductions *);
for (rp = first_reduction; rp; rp = rp->next)
reduction_table[rp->number] = rp;
static void
set_maxrhs (void)
{
- register short *itemp;
- register int length;
- register int max;
+ short *itemp;
+ int length;
+ int max;
length = 0;
max = 0;
}
else
{
- if (length > max) max = length;
+ if (length > max)
+ max = length;
length = 0;
}
}
static void
initialize_LA (void)
{
- register int i;
- register int j;
- register int count;
- register reductions *rp;
- register shifts *sp;
- register short *np;
+ int i;
+ int j;
+ int count;
+ reductions *rp;
+ shifts *sp;
+ short *np;
- consistent = NEW2(nstates, char);
- lookaheads = NEW2(nstates + 1, short);
+ consistent = NEW2 (nstates, char);
+ lookaheads = NEW2 (nstates + 1, short);
count = 0;
for (i = 0; i < nstates; i++)
{
- register int k;
+ int k;
lookaheads[i] = count;
rp = reduction_table[i];
sp = shift_table[i];
if (rp && (rp->nreds > 1
- || (sp && ! ISVAR(accessing_symbol[sp->shifts[0]]))))
+ || (sp && !ISVAR (accessing_symbol[sp->shifts[0]]))))
count += rp->nreds;
else
consistent[i] = 1;
if (count == 0)
{
- LA = NEW2(1 * tokensetsize, unsigned);
- LAruleno = NEW2(1, short);
- lookback = NEW2(1, shorts *);
+ LA = NEW2 (1 * tokensetsize, unsigned);
+ LAruleno = NEW2 (1, short);
+ lookback = NEW2 (1, shorts *);
}
else
{
- LA = NEW2(count * tokensetsize, unsigned);
- LAruleno = NEW2(count, short);
- lookback = NEW2(count, shorts *);
+ LA = NEW2 (count * tokensetsize, unsigned);
+ LAruleno = NEW2 (count, short);
+ lookback = NEW2 (count, shorts *);
}
np = LAruleno;
static void
set_goto_map (void)
{
- register shifts *sp;
- register int i;
- register int symbol;
- register int k;
- register short *temp_map;
- register int state2;
- register int state1;
+ shifts *sp;
+ int i;
+ int symbol;
+ int k;
+ short *temp_map;
+ int state2;
+ int state1;
- goto_map = NEW2(nvars + 1, short) - ntokens;
- temp_map = NEW2(nvars + 1, short) - ntokens;
+ goto_map = NEW2 (nvars + 1, short) - ntokens;
+ temp_map = NEW2 (nvars + 1, short) - ntokens;
ngotos = 0;
for (sp = first_shift; sp; sp = sp->next)
{
symbol = accessing_symbol[sp->shifts[i]];
- if (ISTOKEN(symbol)) break;
+ if (ISTOKEN (symbol))
+ break;
if (ngotos == MAXSHORT)
fatal (_("too many gotos (max %d)"), MAXSHORT);
ngotos++;
goto_map[symbol]++;
- }
+ }
}
k = 0;
goto_map[nsyms] = ngotos;
temp_map[nsyms] = ngotos;
- from_state = NEW2(ngotos, short);
- to_state = NEW2(ngotos, short);
+ from_state = NEW2 (ngotos, short);
+ to_state = NEW2 (ngotos, short);
for (sp = first_shift; sp; sp = sp->next)
{
state2 = sp->shifts[i];
symbol = accessing_symbol[state2];
- if (ISTOKEN(symbol)) break;
+ if (ISTOKEN (symbol))
+ break;
k = temp_map[symbol]++;
from_state[k] = state1;
}
}
- FREE(temp_map + ntokens);
+ FREE (temp_map + ntokens);
}
static int
map_goto (int state, int symbol)
{
- register int high;
- register int low;
- register int middle;
- register int s;
+ int high;
+ int low;
+ int middle;
+ int s;
low = goto_map[symbol];
high = goto_map[symbol + 1] - 1;
high = middle - 1;
}
- berror("map_goto");
+ berror ("map_goto");
/* NOTREACHED */
return 0;
}
static void
initialize_F (void)
{
- register int i;
- register int j;
- register int k;
- register shifts *sp;
- register short *edge;
- register unsigned *rowp;
- register short *rp;
- register short **reads;
- register int nedges;
- register int stateno;
- register int symbol;
- register int nwords;
+ int i;
+ int j;
+ int k;
+ shifts *sp;
+ short *edge;
+ unsigned *rowp;
+ short *rp;
+ short **reads;
+ int nedges;
+ int stateno;
+ int symbol;
+ int nwords;
nwords = ngotos * tokensetsize;
- F = NEW2(nwords, unsigned);
+ F = NEW2 (nwords, unsigned);
- reads = NEW2(ngotos, short *);
- edge = NEW2(ngotos + 1, short);
+ reads = NEW2 (ngotos, short *);
+ edge = NEW2 (ngotos + 1, short);
nedges = 0;
rowp = F;
for (j = 0; j < k; j++)
{
symbol = accessing_symbol[sp->shifts[j]];
- if (ISVAR(symbol))
+ if (ISVAR (symbol))
break;
- SETBIT(rowp, symbol);
+ SETBIT (rowp, symbol);
}
for (; j < k; j++)
{
symbol = accessing_symbol[sp->shifts[j]];
if (nullable[symbol])
- edge[nedges++] = map_goto(stateno, symbol);
+ edge[nedges++] = map_goto (stateno, symbol);
}
if (nedges)
{
- reads[i] = rp = NEW2(nedges + 1, short);
+ reads[i] = rp = NEW2 (nedges + 1, short);
for (j = 0; j < nedges; j++)
rp[j] = edge[j];
rowp += tokensetsize;
}
- digraph(reads);
+ digraph (reads);
for (i = 0; i < ngotos; i++)
{
if (reads[i])
- FREE(reads[i]);
+ FREE (reads[i]);
}
- FREE(reads);
- FREE(edge);
-}
-
-
-static void
-build_relations (void)
-{
- register int i;
- register int j;
- register int k;
- register short *rulep;
- register short *rp;
- register shifts *sp;
- register int length;
- register int nedges;
- register int done;
- register int state1;
- register int stateno;
- register int symbol1;
- register int symbol2;
- register short *shortp;
- register short *edge;
- register short *states;
- register short **new_includes;
-
- includes = NEW2(ngotos, short *);
- edge = NEW2(ngotos + 1, short);
- states = NEW2(maxrhs + 1, short);
-
- for (i = 0; i < ngotos; i++)
- {
- nedges = 0;
- state1 = from_state[i];
- symbol1 = accessing_symbol[to_state[i]];
-
- for (rulep = derives[symbol1]; *rulep > 0; rulep++)
- {
- length = 1;
- states[0] = state1;
- stateno = state1;
-
- for (rp = ritem + rrhs[*rulep]; *rp > 0; rp++)
- {
- symbol2 = *rp;
- sp = shift_table[stateno];
- k = sp->nshifts;
-
- for (j = 0; j < k; j++)
- {
- stateno = sp->shifts[j];
- if (accessing_symbol[stateno] == symbol2) break;
- }
-
- states[length++] = stateno;
- }
-
- if (!consistent[stateno])
- add_lookback_edge(stateno, *rulep, i);
-
- length--;
- done = 0;
- while (!done)
- {
- done = 1;
- rp--;
- /* JF added rp>=ritem && I hope to god its right! */
- if (rp>=ritem && ISVAR(*rp))
- {
- stateno = states[--length];
- edge[nedges++] = map_goto(stateno, *rp);
- if (nullable[*rp]) done = 0;
- }
- }
- }
-
- if (nedges)
- {
- includes[i] = shortp = NEW2(nedges + 1, short);
- for (j = 0; j < nedges; j++)
- shortp[j] = edge[j];
- shortp[nedges] = -1;
- }
- }
-
- new_includes = transpose(includes, ngotos);
-
- for (i = 0; i < ngotos; i++)
- if (includes[i])
- FREE(includes[i]);
-
- FREE(includes);
-
- includes = new_includes;
-
- FREE(edge);
- FREE(states);
+ FREE (reads);
+ FREE (edge);
}
static void
add_lookback_edge (int stateno, int ruleno, int gotono)
{
- register int i;
- register int k;
- register int found;
- register shorts *sp;
+ int i;
+ int k;
+ int found;
+ shorts *sp;
i = lookaheads[stateno];
k = lookaheads[stateno + 1];
i++;
}
- if (found == 0)
- berror("add_lookback_edge");
+ assert (found);
- sp = NEW(shorts);
+ sp = NEW (shorts);
sp->next = lookback[i];
sp->value = gotono;
lookback[i] = sp;
}
-
static short **
transpose (short **R_arg, int n)
{
- register short **new_R;
- register short **temp_R;
- register short *nedges;
- register short *sp;
- register int i;
- register int k;
+ short **new_R;
+ short **temp_R;
+ short *nedges;
+ short *sp;
+ int i;
+ int k;
- nedges = NEW2(n, short);
+ nedges = NEW2 (n, short);
for (i = 0; i < n; i++)
{
}
}
- new_R = NEW2(n, short *);
- temp_R = NEW2(n, short *);
+ new_R = NEW2 (n, short *);
+ temp_R = NEW2 (n, short *);
for (i = 0; i < n; i++)
{
k = nedges[i];
if (k > 0)
{
- sp = NEW2(k + 1, short);
+ sp = NEW2 (k + 1, short);
new_R[i] = sp;
temp_R[i] = sp;
sp[k] = -1;
}
}
- FREE(nedges);
+ FREE (nedges);
for (i = 0; i < n; i++)
{
}
}
- FREE(temp_R);
+ FREE (temp_R);
return new_R;
}
static void
-compute_FOLLOWS (void)
+build_relations (void)
{
- register int i;
-
- digraph(includes);
+ int i;
+ int j;
+ int k;
+ short *rulep;
+ short *rp;
+ shifts *sp;
+ int length;
+ int nedges;
+ int done;
+ int state1;
+ int stateno;
+ int symbol1;
+ int symbol2;
+ short *shortp;
+ short *edge;
+ short *states;
+ short **new_includes;
+
+ includes = NEW2 (ngotos, short *);
+ edge = NEW2 (ngotos + 1, short);
+ states = NEW2 (maxrhs + 1, short);
for (i = 0; i < ngotos; i++)
{
- if (includes[i]) FREE(includes[i]);
- }
+ nedges = 0;
+ state1 = from_state[i];
+ symbol1 = accessing_symbol[to_state[i]];
- FREE(includes);
-}
+ for (rulep = derives[symbol1]; *rulep > 0; rulep++)
+ {
+ length = 1;
+ states[0] = state1;
+ stateno = state1;
+ for (rp = ritem + rrhs[*rulep]; *rp > 0; rp++)
+ {
+ symbol2 = *rp;
+ sp = shift_table[stateno];
+ k = sp->nshifts;
-static void
-compute_lookaheads (void)
-{
- register int i;
- register int n;
- register unsigned *fp1;
- register unsigned *fp2;
- register unsigned *fp3;
- register shorts *sp;
- register unsigned *rowp;
-/* register short *rulep; JF unused */
-/* register int count; JF unused */
- register shorts *sptmp;/* JF */
+ for (j = 0; j < k; j++)
+ {
+ stateno = sp->shifts[j];
+ if (accessing_symbol[stateno] == symbol2)
+ break;
+ }
- rowp = LA;
- n = lookaheads[nstates];
- for (i = 0; i < n; i++)
- {
- fp3 = rowp + tokensetsize;
- for (sp = lookback[i]; sp; sp = sp->next)
- {
- fp1 = rowp;
- fp2 = F + tokensetsize * sp->value;
- while (fp1 < fp3)
- *fp1++ |= *fp2++;
+ states[length++] = stateno;
+ }
+
+ if (!consistent[stateno])
+ add_lookback_edge (stateno, *rulep, i);
+
+ length--;
+ done = 0;
+ while (!done)
+ {
+ done = 1;
+ rp--;
+ /* JF added rp>=ritem && I hope to god its right! */
+ if (rp >= ritem && ISVAR (*rp))
+ {
+ stateno = states[--length];
+ edge[nedges++] = map_goto (stateno, *rp);
+ if (nullable[*rp])
+ done = 0;
+ }
+ }
}
- rowp = fp3;
+ if (nedges)
+ {
+ includes[i] = shortp = NEW2 (nedges + 1, short);
+ for (j = 0; j < nedges; j++)
+ shortp[j] = edge[j];
+ shortp[nedges] = -1;
+ }
}
- for (i = 0; i < n; i++)
- {/* JF removed ref to freed storage */
- for (sp = lookback[i]; sp; sp = sptmp) {
- sptmp=sp->next;
- FREE(sp);
- }
- }
+ new_includes = transpose (includes, ngotos);
- FREE(lookback);
- FREE(F);
+ for (i = 0; i < ngotos; i++)
+ if (includes[i])
+ FREE (includes[i]);
+
+ FREE (includes);
+
+ includes = new_includes;
+
+ FREE (edge);
+ FREE (states);
}
+
static void
-digraph (short **relation)
+compute_FOLLOWS (void)
{
- register int i;
+ int i;
- infinity = ngotos + 2;
- INDEX = NEW2(ngotos + 1, short);
- VERTICES = NEW2(ngotos + 1, short);
- top = 0;
-
- R = relation;
-
- for (i = 0; i < ngotos; i++)
- INDEX[i] = 0;
+ digraph (includes);
for (i = 0; i < ngotos; i++)
{
- if (INDEX[i] == 0 && R[i])
- traverse(i);
+ if (includes[i])
+ FREE (includes[i]);
}
- FREE(INDEX);
- FREE(VERTICES);
+ FREE (includes);
}
static void
-traverse (register int i)
+compute_lookaheads (void)
{
- register unsigned *fp1;
- register unsigned *fp2;
- register unsigned *fp3;
- register int j;
- register short *rp;
-
- int height;
- unsigned *base;
-
- VERTICES[++top] = i;
- INDEX[i] = height = top;
-
- base = F + i * tokensetsize;
- fp3 = base + tokensetsize;
+ int i;
+ int n;
+ unsigned *fp1;
+ unsigned *fp2;
+ unsigned *fp3;
+ shorts *sp;
+ unsigned *rowp;
+ shorts *sptmp; /* JF */
- rp = R[i];
- if (rp)
+ rowp = LA;
+ n = lookaheads[nstates];
+ for (i = 0; i < n; i++)
{
- while ((j = *rp++) >= 0)
+ fp3 = rowp + tokensetsize;
+ for (sp = lookback[i]; sp; sp = sp->next)
{
- if (INDEX[j] == 0)
- traverse(j);
-
- if (INDEX[i] > INDEX[j])
- INDEX[i] = INDEX[j];
-
- fp1 = base;
- fp2 = F + j * tokensetsize;
-
+ fp1 = rowp;
+ fp2 = F + tokensetsize * sp->value;
while (fp1 < fp3)
*fp1++ |= *fp2++;
}
+
+ rowp = fp3;
}
- if (INDEX[i] == height)
+ for (i = 0; i < n; i++)
{
- for (;;)
+ /* JF removed ref to freed storage */
+ for (sp = lookback[i]; sp; sp = sptmp)
{
- j = VERTICES[top--];
- INDEX[j] = infinity;
+ sptmp = sp->next;
+ FREE (sp);
+ }
+ }
- if (i == j)
- break;
+ FREE (lookback);
+ FREE (F);
+}
- fp1 = base;
- fp2 = F + j * tokensetsize;
- while (fp1 < fp3)
- *fp2++ = *fp1++;
- }
- }
+void
+lalr (void)
+{
+ tokensetsize = WORDSIZE (ntokens);
+
+ set_state_table ();
+ set_accessing_symbol ();
+ set_shift_table ();
+ set_reduction_table ();
+ set_maxrhs ();
+ initialize_LA ();
+ set_goto_map ();
+ initialize_F ();
+ build_relations ();
+ compute_FOLLOWS ();
+ compute_lookaheads ();
}
projects / bison.git / blobdiff