373 lines
7.0 KiB
C
373 lines
7.0 KiB
C
/***********************************************************************/
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/* */
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/* Objective Caml */
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/* */
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/* Xavier Leroy, projet Cristal, INRIA Rocquencourt */
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/* */
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/* Copyright 1996 Institut National de Recherche en Informatique et */
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/* Automatique. Distributed only by permission. */
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/* */
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/***********************************************************************/
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/* Based on public-domain code from Berkeley Yacc */
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/* $Id$ */
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#include "defs.h"
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action **parser;
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int SRtotal;
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int RRtotal;
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short *SRconflicts;
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short *RRconflicts;
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short *defred;
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short *rules_used;
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short nunused;
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short final_state;
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static int SRcount;
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static int RRcount;
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void find_final_state ();
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void remove_conflicts ();
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void unused_rules ();
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void total_conflicts ();
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void defreds ();
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void make_parser()
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{
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register int i;
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parser = NEW2(nstates, action *);
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for (i = 0; i < nstates; i++)
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parser[i] = parse_actions(i);
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find_final_state();
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remove_conflicts();
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unused_rules();
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if (SRtotal + RRtotal > 0) total_conflicts();
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defreds();
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}
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action *
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parse_actions(stateno)
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register int stateno;
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{
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register action *actions;
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actions = get_shifts(stateno);
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actions = add_reductions(stateno, actions);
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return (actions);
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}
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action *
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get_shifts(stateno)
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int stateno;
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{
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register action *actions, *temp;
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register shifts *sp;
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register short *to_state;
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register int i, k;
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register int symbol;
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actions = 0;
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sp = shift_table[stateno];
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if (sp)
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{
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to_state = sp->shift;
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for (i = sp->nshifts - 1; i >= 0; i--)
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{
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k = to_state[i];
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symbol = accessing_symbol[k];
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if (ISTOKEN(symbol))
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{
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temp = NEW(action);
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temp->next = actions;
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temp->symbol = symbol;
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temp->number = k;
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temp->prec = symbol_prec[symbol];
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temp->action_code = SHIFT;
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temp->assoc = symbol_assoc[symbol];
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actions = temp;
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}
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}
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}
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return (actions);
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}
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action *
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add_reductions(stateno, actions)
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int stateno;
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register action *actions;
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{
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register int i, j, m, n;
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register int ruleno, tokensetsize;
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register unsigned *rowp;
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tokensetsize = WORDSIZE(ntokens);
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m = lookaheads[stateno];
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n = lookaheads[stateno + 1];
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for (i = m; i < n; i++)
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{
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ruleno = LAruleno[i];
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rowp = LA + i * tokensetsize;
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for (j = ntokens - 1; j >= 0; j--)
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{
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if (BIT(rowp, j))
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actions = add_reduce(actions, ruleno, j);
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}
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}
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return (actions);
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}
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action *
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add_reduce(actions, ruleno, symbol)
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register action *actions;
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register int ruleno;
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register int symbol;
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{
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register action *temp, *prev, *next;
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prev = 0;
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for (next = actions; next && next->symbol < symbol; next = next->next)
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prev = next;
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while (next && next->symbol == symbol && next->action_code == SHIFT)
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{
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prev = next;
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next = next->next;
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}
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while (next && next->symbol == symbol &&
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next->action_code == REDUCE && next->number < ruleno)
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{
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prev = next;
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next = next->next;
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}
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temp = NEW(action);
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temp->next = next;
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temp->symbol = symbol;
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temp->number = ruleno;
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temp->prec = rprec[ruleno];
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temp->action_code = REDUCE;
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temp->assoc = rassoc[ruleno];
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if (prev)
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prev->next = temp;
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else
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actions = temp;
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return (actions);
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}
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void find_final_state()
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{
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register int goal, i;
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register short *to_state;
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register shifts *p;
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p = shift_table[0];
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to_state = p->shift;
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goal = ritem[1];
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for (i = p->nshifts - 1; i >= 0; --i)
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{
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final_state = to_state[i];
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if (accessing_symbol[final_state] == goal) break;
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}
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}
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void unused_rules()
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{
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register int i;
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register action *p;
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rules_used = (short *) MALLOC(nrules*sizeof(short));
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if (rules_used == 0) no_space();
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for (i = 0; i < nrules; ++i)
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rules_used[i] = 0;
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for (i = 0; i < nstates; ++i)
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{
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for (p = parser[i]; p; p = p->next)
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{
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if (p->action_code == REDUCE && p->suppressed == 0)
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rules_used[p->number] = 1;
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}
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}
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nunused = 0;
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for (i = 3; i < nrules; ++i)
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if (!rules_used[i]) ++nunused;
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if (nunused)
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if (nunused == 1)
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fprintf(stderr, "1 rule never reduced\n");
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else
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fprintf(stderr, "%d rules never reduced\n", nunused);
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}
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void remove_conflicts()
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{
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register int i;
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register int symbol;
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register action *p, *pref;
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SRtotal = 0;
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RRtotal = 0;
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SRconflicts = NEW2(nstates, short);
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RRconflicts = NEW2(nstates, short);
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for (i = 0; i < nstates; i++)
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{
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SRcount = 0;
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RRcount = 0;
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symbol = -1;
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for (p = parser[i]; p; p = p->next)
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{
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if (p->symbol != symbol)
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{
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pref = p;
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symbol = p->symbol;
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}
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else if (i == final_state && symbol == 0)
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{
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SRcount++;
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p->suppressed = 1;
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}
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else if (pref->action_code == SHIFT)
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{
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if (pref->prec > 0 && p->prec > 0)
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{
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if (pref->prec < p->prec)
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{
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pref->suppressed = 2;
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pref = p;
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}
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else if (pref->prec > p->prec)
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{
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p->suppressed = 2;
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}
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else if (pref->assoc == LEFT)
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{
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pref->suppressed = 2;
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pref = p;
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}
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else if (pref->assoc == RIGHT)
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{
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p->suppressed = 2;
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}
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else
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{
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pref->suppressed = 2;
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p->suppressed = 2;
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}
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}
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else
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{
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SRcount++;
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p->suppressed = 1;
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}
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}
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else
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{
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RRcount++;
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p->suppressed = 1;
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}
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}
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SRtotal += SRcount;
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RRtotal += RRcount;
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SRconflicts[i] = SRcount;
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RRconflicts[i] = RRcount;
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}
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}
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void total_conflicts()
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{
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if (SRtotal == 1)
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fprintf(stderr, "1 shift/reduce conflict");
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else if (SRtotal > 1)
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fprintf(stderr, "%d shift/reduce conflicts", SRtotal);
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if (SRtotal && RRtotal)
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fprintf(stderr, ", ");
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if (RRtotal == 1)
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fprintf(stderr, "1 reduce/reduce conflict");
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else if (RRtotal > 1)
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fprintf(stderr, "%d reduce/reduce conflicts", RRtotal);
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fprintf(stderr, ".\n");
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}
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int
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sole_reduction(stateno)
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int stateno;
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{
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register int count, ruleno;
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register action *p;
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count = 0;
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ruleno = 0;
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for (p = parser[stateno]; p; p = p->next)
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{
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if (p->action_code == SHIFT && p->suppressed == 0)
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return (0);
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else if (p->action_code == REDUCE && p->suppressed == 0)
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{
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if (ruleno > 0 && p->number != ruleno)
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return (0);
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if (p->symbol != 1)
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++count;
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ruleno = p->number;
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}
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}
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if (count == 0)
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return (0);
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return (ruleno);
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}
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void defreds()
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{
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register int i;
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defred = NEW2(nstates, short);
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for (i = 0; i < nstates; i++)
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defred[i] = sole_reduction(i);
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}
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void free_action_row(p)
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register action *p;
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{
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register action *q;
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while (p)
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{
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q = p->next;
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FREE(p);
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p = q;
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}
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}
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void free_parser()
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{
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register int i;
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for (i = 0; i < nstates; i++)
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free_action_row(parser[i]);
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FREE(parser);
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}
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