freebsd-dev/contrib/byacc/mkpar.c
Baptiste Daroussin 0c8de5b03c Update to byacc 20140409
Among all the modifications, this new byacc also solves a 14 year old bug [1]

PR:		bin/23254 [1]
Submitted by:	marka@nominum.com [1]
MFC after:	3 weeks
2014-04-23 05:57:45 +00:00

412 lines
7.7 KiB
C

/* $Id: mkpar.c,v 1.14 2014/04/01 23:05:37 tom Exp $ */
#include "defs.h"
#define NotSuppressed(p) ((p)->suppressed == 0)
#if defined(YYBTYACC)
#define MaySuppress(p) ((backtrack ? ((p)->suppressed <= 1) : (p)->suppressed == 0))
/* suppress the preferred action => enable backtracking */
#define StartBacktrack(p) if (backtrack && (p) != NULL && NotSuppressed(p)) (p)->suppressed = 1
#else
#define MaySuppress(p) ((p)->suppressed == 0)
#define StartBacktrack(p) /*nothing */
#endif
static action *add_reduce(action *actions, int ruleno, int symbol);
static action *add_reductions(int stateno, action *actions);
static action *get_shifts(int stateno);
static action *parse_actions(int stateno);
static int sole_reduction(int stateno);
static void defreds(void);
static void find_final_state(void);
static void free_action_row(action *p);
static void remove_conflicts(void);
static void total_conflicts(void);
static void unused_rules(void);
action **parser;
int SRexpect;
int RRexpect;
int SRtotal;
int RRtotal;
Value_t *SRconflicts;
Value_t *RRconflicts;
Value_t *defred;
Value_t *rules_used;
Value_t nunused;
Value_t final_state;
static Value_t SRcount;
static Value_t RRcount;
void
make_parser(void)
{
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();
}
static action *
parse_actions(int stateno)
{
action *actions;
actions = get_shifts(stateno);
actions = add_reductions(stateno, actions);
return (actions);
}
static action *
get_shifts(int stateno)
{
action *actions, *temp;
shifts *sp;
Value_t *to_state2;
Value_t i, k;
Value_t symbol;
actions = 0;
sp = shift_table[stateno];
if (sp)
{
to_state2 = sp->shift;
for (i = (Value_t) (sp->nshifts - 1); i >= 0; i--)
{
k = to_state2[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);
}
static action *
add_reductions(int stateno, action *actions)
{
int i, j, m, n;
int ruleno, tokensetsize;
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);
}
static action *
add_reduce(action *actions,
int ruleno,
int symbol)
{
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 = (Value_t) symbol;
temp->number = (Value_t) ruleno;
temp->prec = rprec[ruleno];
temp->action_code = REDUCE;
temp->assoc = rassoc[ruleno];
if (prev)
prev->next = temp;
else
actions = temp;
return (actions);
}
static void
find_final_state(void)
{
int goal, i;
Value_t *to_state2;
shifts *p;
p = shift_table[0];
to_state2 = p->shift;
goal = ritem[1];
for (i = p->nshifts - 1; i >= 0; --i)
{
final_state = to_state2[i];
if (accessing_symbol[final_state] == goal)
break;
}
}
static void
unused_rules(void)
{
int i;
action *p;
rules_used = TMALLOC(Value_t, nrules);
NO_SPACE(rules_used);
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) && MaySuppress(p))
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);
}
}
static void
remove_conflicts(void)
{
int i;
int symbol;
action *p, *pref = 0;
SRtotal = 0;
RRtotal = 0;
SRconflicts = NEW2(nstates, Value_t);
RRconflicts = NEW2(nstates, Value_t);
for (i = 0; i < nstates; i++)
{
SRcount = 0;
RRcount = 0;
symbol = -1;
#if defined(YYBTYACC)
pref = NULL;
#endif
for (p = parser[i]; p; p = p->next)
{
if (p->symbol != symbol)
{
/* the first parse action for each symbol is the preferred action */
pref = p;
symbol = p->symbol;
}
/* following conditions handle multiple, i.e., conflicting, parse actions */
else if (i == final_state && symbol == 0)
{
SRcount++;
p->suppressed = 1;
StartBacktrack(pref);
}
else if (pref != 0 && 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;
StartBacktrack(pref);
}
}
else
{
RRcount++;
p->suppressed = 1;
StartBacktrack(pref);
}
}
SRtotal += SRcount;
RRtotal += RRcount;
SRconflicts[i] = SRcount;
RRconflicts[i] = RRcount;
}
}
static void
total_conflicts(void)
{
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");
if (SRexpect >= 0 && SRtotal != SRexpect)
{
fprintf(stderr, "%s: ", myname);
fprintf(stderr, "expected %d shift/reduce conflict%s.\n",
SRexpect, PLURAL(SRexpect));
exit_code = EXIT_FAILURE;
}
if (RRexpect >= 0 && RRtotal != RRexpect)
{
fprintf(stderr, "%s: ", myname);
fprintf(stderr, "expected %d reduce/reduce conflict%s.\n",
RRexpect, PLURAL(RRexpect));
exit_code = EXIT_FAILURE;
}
}
static int
sole_reduction(int stateno)
{
int count, ruleno;
action *p;
count = 0;
ruleno = 0;
for (p = parser[stateno]; p; p = p->next)
{
if (p->action_code == SHIFT && MaySuppress(p))
return (0);
else if ((p->action_code == REDUCE) && MaySuppress(p))
{
if (ruleno > 0 && p->number != ruleno)
return (0);
if (p->symbol != 1)
++count;
ruleno = p->number;
}
}
if (count == 0)
return (0);
return (ruleno);
}
static void
defreds(void)
{
int i;
defred = NEW2(nstates, Value_t);
for (i = 0; i < nstates; i++)
defred[i] = (Value_t) sole_reduction(i);
}
static void
free_action_row(action *p)
{
action *q;
while (p)
{
q = p->next;
FREE(p);
p = q;
}
}
void
free_parser(void)
{
int i;
for (i = 0; i < nstates; i++)
free_action_row(parser[i]);
FREE(parser);
}
#ifdef NO_LEAKS
void
mkpar_leaks(void)
{
DO_FREE(defred);
DO_FREE(rules_used);
DO_FREE(SRconflicts);
DO_FREE(RRconflicts);
}
#endif