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ocaml/yacc/lalr.c

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/***********************************************************************/
/* */
/* Objective Caml */
/* */
/* Xavier Leroy, projet Cristal, INRIA Rocquencourt */
/* */
/* Copyright 1996 Institut National de Recherche en Informatique et */
/* Automatique. Distributed only by permission. */
/* */
/***********************************************************************/
/* Based on public-domain code from Berkeley Yacc */
/* $Id$ */
#include "defs.h"
typedef
struct shorts
{
struct shorts *next;
short value;
}
shorts;
int tokensetsize;
short *lookaheads;
short *LAruleno;
unsigned *LA;
short *accessing_symbol;
core **state_table;
shifts **shift_table;
reductions **reduction_table;
short *goto_map;
short *from_state;
short *to_state;
short **transpose();
static int infinity;
static int maxrhs;
static int ngotos;
static unsigned *F;
static short **includes;
static shorts **lookback;
static short **R;
static short *INDEX;
static short *VERTICES;
static int top;
void set_state_table ();
void set_accessing_symbol ();
void set_shift_table ();
void set_reduction_table ();
void set_maxrhs ();
void initialize_LA ();
void set_goto_map ();
void initialize_F ();
void build_relations ();
void compute_FOLLOWS ();
void compute_lookaheads ();
void digraph ();
void add_lookback_edge ();
void traverse ();
void lalr()
{
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();
}
void set_state_table()
{
register core *sp;
state_table = NEW2(nstates, core *);
for (sp = first_state; sp; sp = sp->next)
state_table[sp->number] = sp;
}
void set_accessing_symbol()
{
register core *sp;
accessing_symbol = NEW2(nstates, short);
for (sp = first_state; sp; sp = sp->next)
accessing_symbol[sp->number] = sp->accessing_symbol;
}
void set_shift_table()
{
register shifts *sp;
shift_table = NEW2(nstates, shifts *);
for (sp = first_shift; sp; sp = sp->next)
shift_table[sp->number] = sp;
}
void set_reduction_table()
{
register reductions *rp;
reduction_table = NEW2(nstates, reductions *);
for (rp = first_reduction; rp; rp = rp->next)
reduction_table[rp->number] = rp;
}
void set_maxrhs()
{
register short *itemp;
register short *item_end;
register int length;
register int max;
length = 0;
max = 0;
item_end = ritem + nitems;
for (itemp = ritem; itemp < item_end; itemp++)
{
if (*itemp >= 0)
{
length++;
}
else
{
if (length > max) max = length;
length = 0;
}
}
maxrhs = max;
}
void initialize_LA()
{
register int i, j, k;
register reductions *rp;
lookaheads = NEW2(nstates + 1, short);
k = 0;
for (i = 0; i < nstates; i++)
{
lookaheads[i] = k;
rp = reduction_table[i];
if (rp)
k += rp->nreds;
}
lookaheads[nstates] = k;
LA = NEW2(k * tokensetsize, unsigned);
LAruleno = NEW2(k, short);
lookback = NEW2(k, shorts *);
k = 0;
for (i = 0; i < nstates; i++)
{
rp = reduction_table[i];
if (rp)
{
for (j = 0; j < rp->nreds; j++)
{
LAruleno[k] = rp->rules[j];
k++;
}
}
}
}
void set_goto_map()
{
register shifts *sp;
register int i;
register int symbol;
register int k;
register short *temp_map;
register int state2;
register int state1;
goto_map = NEW2(nvars + 1, short) - ntokens;
temp_map = NEW2(nvars + 1, short) - ntokens;
ngotos = 0;
for (sp = first_shift; sp; sp = sp->next)
{
for (i = sp->nshifts - 1; i >= 0; i--)
{
symbol = accessing_symbol[sp->shift[i]];
if (ISTOKEN(symbol)) break;
if (ngotos == MAXSHORT)
fatal("too many gotos");
ngotos++;
goto_map[symbol]++;
}
}
k = 0;
for (i = ntokens; i < nsyms; i++)
{
temp_map[i] = k;
k += goto_map[i];
}
for (i = ntokens; i < nsyms; i++)
goto_map[i] = temp_map[i];
goto_map[nsyms] = ngotos;
temp_map[nsyms] = ngotos;
from_state = NEW2(ngotos, short);
to_state = NEW2(ngotos, short);
for (sp = first_shift; sp; sp = sp->next)
{
state1 = sp->number;
for (i = sp->nshifts - 1; i >= 0; i--)
{
state2 = sp->shift[i];
symbol = accessing_symbol[state2];
if (ISTOKEN(symbol)) break;
k = temp_map[symbol]++;
from_state[k] = state1;
to_state[k] = state2;
}
}
FREE(temp_map + ntokens);
}
/* Map_goto maps a state/symbol pair into its numeric representation. */
int
map_goto(state, symbol)
int state;
int symbol;
{
register int high;
register int low;
register int middle;
register int s;
low = goto_map[symbol];
high = goto_map[symbol + 1];
for (;;)
{
assert(low <= high);
middle = (low + high) >> 1;
s = from_state[middle];
if (s == state)
return (middle);
else if (s < state)
low = middle + 1;
else
high = middle - 1;
}
}
void initialize_F()
{
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;
nwords = ngotos * tokensetsize;
F = NEW2(nwords, unsigned);
reads = NEW2(ngotos, short *);
edge = NEW2(ngotos + 1, short);
nedges = 0;
rowp = F;
for (i = 0; i < ngotos; i++)
{
stateno = to_state[i];
sp = shift_table[stateno];
if (sp)
{
k = sp->nshifts;
for (j = 0; j < k; j++)
{
symbol = accessing_symbol[sp->shift[j]];
if (ISVAR(symbol))
break;
SETBIT(rowp, symbol);
}
for (; j < k; j++)
{
symbol = accessing_symbol[sp->shift[j]];
if (nullable[symbol])
edge[nedges++] = map_goto(stateno, symbol);
}
if (nedges)
{
reads[i] = rp = NEW2(nedges + 1, short);
for (j = 0; j < nedges; j++)
rp[j] = edge[j];
rp[nedges] = -1;
nedges = 0;
}
}
rowp += tokensetsize;
}
SETBIT(F, 0);
digraph(reads);
for (i = 0; i < ngotos; i++)
{
if (reads[i])
FREE(reads[i]);
}
FREE(reads);
FREE(edge);
}
void build_relations()
{
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->shift[j];
if (accessing_symbol[stateno] == symbol2) break;
}
states[length++] = stateno;
}
add_lookback_edge(stateno, *rulep, i);
length--;
done = 0;
while (!done)
{
done = 1;
rp--;
if (ISVAR(*rp))
{
stateno = states[--length];
edge[nedges++] = map_goto(stateno, *rp);
if (nullable[*rp] && length > 0) 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);
}
void add_lookback_edge(stateno, ruleno, gotono)
int stateno;
int ruleno;
int gotono;
{
register int i, k;
register int found;
register shorts *sp;
i = lookaheads[stateno];
k = lookaheads[stateno + 1];
found = 0;
while (!found && i < k)
{
if (LAruleno[i] == ruleno)
found = 1;
else
++i;
}
assert(found);
sp = NEW(shorts);
sp->next = lookback[i];
sp->value = gotono;
lookback[i] = sp;
}
short **
transpose(R, n)
short int **R;
int n;
{
register short **new_R;
register short **temp_R;
register short *nedges;
register short *sp;
register int i;
register int k;
nedges = NEW2(n, short);
for (i = 0; i < n; i++)
{
sp = R[i];
if (sp)
{
while (*sp >= 0)
nedges[*sp++]++;
}
}
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);
new_R[i] = sp;
temp_R[i] = sp;
sp[k] = -1;
}
}
FREE(nedges);
for (i = 0; i < n; i++)
{
sp = R[i];
if (sp)
{
while (*sp >= 0)
*temp_R[*sp++]++ = i;
}
}
FREE(temp_R);
return (new_R);
}
void compute_FOLLOWS()
{
digraph(includes);
}
void compute_lookaheads()
{
register int i, n;
register unsigned *fp1, *fp2, *fp3;
register shorts *sp, *next;
register unsigned *rowp;
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++;
}
rowp = fp3;
}
for (i = 0; i < n; i++)
for (sp = lookback[i]; sp; sp = next)
{
next = sp->next;
FREE(sp);
}
FREE(lookback);
FREE(F);
}
void digraph(relation)
short int **relation;
{
register 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);
}
void traverse(i)
register int i;
{
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;
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++;
}
}
}
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