4.4BSD/usr/src/usr.bin/yacc/mkpar.c
/*
* Copyright (c) 1989 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Robert Paul Corbett.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
static char sccsid[] = "@(#)mkpar.c 5.3 (Berkeley) 1/20/91";
#endif /* not lint */
#include "defs.h"
action **parser;
int SRtotal;
int RRtotal;
short *SRconflicts;
short *RRconflicts;
short *defred;
short *rules_used;
short nunused;
short final_state;
static int SRcount;
static int RRcount;
extern action *parse_actions();
extern action *get_shifts();
extern action *add_reductions();
extern action *add_reduce();
make_parser()
{
register int i;
parser = NEW2(nstates, action *);
for (i = 0; i < nstates; i++)
parser[i] = parse_actions(i);
find_final_state();
remove_conflicts();
unused_rules();
if (SRtotal + RRtotal > 0) total_conflicts();
defreds();
}
action *
parse_actions(stateno)
register int stateno;
{
register action *actions;
actions = get_shifts(stateno);
actions = add_reductions(stateno, actions);
return (actions);
}
action *
get_shifts(stateno)
int stateno;
{
register action *actions, *temp;
register shifts *sp;
register short *to_state;
register int i, k;
register int symbol;
actions = 0;
sp = shift_table[stateno];
if (sp)
{
to_state = sp->shift;
for (i = sp->nshifts - 1; i >= 0; i--)
{
k = to_state[i];
symbol = accessing_symbol[k];
if (ISTOKEN(symbol))
{
temp = NEW(action);
temp->next = actions;
temp->symbol = symbol;
temp->number = k;
temp->prec = symbol_prec[symbol];
temp->action_code = SHIFT;
temp->assoc = symbol_assoc[symbol];
actions = temp;
}
}
}
return (actions);
}
action *
add_reductions(stateno, actions)
int stateno;
register action *actions;
{
register int i, j, m, n;
register int ruleno, tokensetsize;
register unsigned *rowp;
tokensetsize = WORDSIZE(ntokens);
m = lookaheads[stateno];
n = lookaheads[stateno + 1];
for (i = m; i < n; i++)
{
ruleno = LAruleno[i];
rowp = LA + i * tokensetsize;
for (j = ntokens - 1; j >= 0; j--)
{
if (BIT(rowp, j))
actions = add_reduce(actions, ruleno, j);
}
}
return (actions);
}
action *
add_reduce(actions, ruleno, symbol)
register action *actions;
register int ruleno, symbol;
{
register action *temp, *prev, *next;
prev = 0;
for (next = actions; next && next->symbol < symbol; next = next->next)
prev = next;
while (next && next->symbol == symbol && next->action_code == SHIFT)
{
prev = next;
next = next->next;
}
while (next && next->symbol == symbol &&
next->action_code == REDUCE && next->number < ruleno)
{
prev = next;
next = next->next;
}
temp = NEW(action);
temp->next = next;
temp->symbol = symbol;
temp->number = ruleno;
temp->prec = rprec[ruleno];
temp->action_code = REDUCE;
temp->assoc = rassoc[ruleno];
if (prev)
prev->next = temp;
else
actions = temp;
return (actions);
}
find_final_state()
{
register int goal, i;
register short *to_state;
register shifts *p;
p = shift_table[0];
to_state = p->shift;
goal = ritem[1];
for (i = p->nshifts - 1; i >= 0; --i)
{
final_state = to_state[i];
if (accessing_symbol[final_state] == goal) break;
}
}
unused_rules()
{
register int i;
register action *p;
rules_used = (short *) MALLOC(nrules*sizeof(short));
if (rules_used == 0) no_space();
for (i = 0; i < nrules; ++i)
rules_used[i] = 0;
for (i = 0; i < nstates; ++i)
{
for (p = parser[i]; p; p = p->next)
{
if (p->action_code == REDUCE && p->suppressed == 0)
rules_used[p->number] = 1;
}
}
nunused = 0;
for (i = 3; i < nrules; ++i)
if (!rules_used[i]) ++nunused;
if (nunused)
if (nunused == 1)
fprintf(stderr, "%s: 1 rule never reduced\n", myname);
else
fprintf(stderr, "%s: %d rules never reduced\n", myname, nunused);
}
remove_conflicts()
{
register int i;
register int symbol;
register action *p, *pref;
SRtotal = 0;
RRtotal = 0;
SRconflicts = NEW2(nstates, short);
RRconflicts = NEW2(nstates, short);
for (i = 0; i < nstates; i++)
{
SRcount = 0;
RRcount = 0;
symbol = -1;
for (p = parser[i]; p; p = p->next)
{
if (p->symbol != symbol)
{
pref = p;
symbol = p->symbol;
}
else if (i == final_state && symbol == 0)
{
SRcount++;
p->suppressed = 1;
}
else if (pref->action_code == SHIFT)
{
if (pref->prec > 0 && p->prec > 0)
{
if (pref->prec < p->prec)
{
pref->suppressed = 2;
pref = p;
}
else if (pref->prec > p->prec)
{
p->suppressed = 2;
}
else if (pref->assoc == LEFT)
{
pref->suppressed = 2;
pref = p;
}
else if (pref->assoc == RIGHT)
{
p->suppressed = 2;
}
else
{
pref->suppressed = 2;
p->suppressed = 2;
}
}
else
{
SRcount++;
p->suppressed = 1;
}
}
else
{
RRcount++;
p->suppressed = 1;
}
}
SRtotal += SRcount;
RRtotal += RRcount;
SRconflicts[i] = SRcount;
RRconflicts[i] = RRcount;
}
}
total_conflicts()
{
fprintf(stderr, "%s: ", myname);
if (SRtotal == 1)
fprintf(stderr, "1 shift/reduce conflict");
else if (SRtotal > 1)
fprintf(stderr, "%d shift/reduce conflicts", SRtotal);
if (SRtotal && RRtotal)
fprintf(stderr, ", ");
if (RRtotal == 1)
fprintf(stderr, "1 reduce/reduce conflict");
else if (RRtotal > 1)
fprintf(stderr, "%d reduce/reduce conflicts", RRtotal);
fprintf(stderr, ".\n");
}
int
sole_reduction(stateno)
int stateno;
{
register int count, ruleno;
register action *p;
count = 0;
ruleno = 0;
for (p = parser[stateno]; p; p = p->next)
{
if (p->action_code == SHIFT && p->suppressed == 0)
return (0);
else if (p->action_code == REDUCE && p->suppressed == 0)
{
if (ruleno > 0 && p->number != ruleno)
return (0);
if (p->symbol != 1)
++count;
ruleno = p->number;
}
}
if (count == 0)
return (0);
return (ruleno);
}
defreds()
{
register int i;
defred = NEW2(nstates, short);
for (i = 0; i < nstates; i++)
defred[i] = sole_reduction(i);
}
free_action_row(p)
register action *p;
{
register action *q;
while (p)
{
q = p->next;
FREE(p);
p = q;
}
}
free_parser()
{
register int i;
for (i = 0; i < nstates; i++)
free_action_row(parser[i]);
FREE(parser);
}