414 lines
7.7 KiB
C
414 lines
7.7 KiB
C
/* $Id: mkpar.c,v 1.16 2019/11/04 01:23:02 tom Exp $ */
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#include "defs.h"
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#define NotSuppressed(p) ((p)->suppressed == 0)
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#if defined(YYBTYACC)
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#define MaySuppress(p) ((backtrack ? ((p)->suppressed <= 1) : (p)->suppressed == 0))
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/* suppress the preferred action => enable backtracking */
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#define StartBacktrack(p) if (backtrack && (p) != NULL && NotSuppressed(p)) (p)->suppressed = 1
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#else
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#define MaySuppress(p) ((p)->suppressed == 0)
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#define StartBacktrack(p) /*nothing */
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#endif
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static action *add_reduce(action *actions, int ruleno, int symbol);
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static action *add_reductions(int stateno, action *actions);
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static action *get_shifts(int stateno);
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static action *parse_actions(int stateno);
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static int sole_reduction(int stateno);
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static void defreds(void);
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static void find_final_state(void);
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static void free_action_row(action *p);
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static void remove_conflicts(void);
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static void total_conflicts(void);
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static void unused_rules(void);
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action **parser;
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int SRexpect;
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int RRexpect;
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int SRtotal;
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int RRtotal;
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Value_t *SRconflicts;
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Value_t *RRconflicts;
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Value_t *defred;
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Value_t *rules_used;
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Value_t nunused;
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Value_t final_state;
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static Value_t SRcount;
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static Value_t RRcount;
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void
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make_parser(void)
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{
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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)
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total_conflicts();
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defreds();
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}
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static action *
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parse_actions(int stateno)
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{
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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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static action *
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get_shifts(int stateno)
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{
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action *actions, *temp;
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shifts *sp;
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Value_t *to_state2;
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Value_t i, k;
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Value_t 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_state2 = sp->shift;
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for (i = (Value_t)(sp->nshifts - 1); i >= 0; i--)
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{
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k = to_state2[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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static action *
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add_reductions(int stateno, action *actions)
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{
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int i, j, m, n;
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int ruleno, tokensetsize;
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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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static action *
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add_reduce(action *actions,
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int ruleno,
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int symbol)
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{
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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 = (Value_t)symbol;
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temp->number = (Value_t)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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static void
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find_final_state(void)
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{
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int goal, i;
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Value_t *to_state2;
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shifts *p;
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if ((p = shift_table[0]) != 0)
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{
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to_state2 = 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_state2[i];
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if (accessing_symbol[final_state] == goal)
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break;
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}
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}
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}
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static void
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unused_rules(void)
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{
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int i;
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action *p;
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rules_used = TMALLOC(Value_t, nrules);
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NO_SPACE(rules_used);
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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) && MaySuppress(p))
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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])
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++nunused;
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if (nunused)
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{
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if (nunused == 1)
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fprintf(stderr, "%s: 1 rule never reduced\n", myname);
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else
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fprintf(stderr, "%s: %d rules never reduced\n", myname, nunused);
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}
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}
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static void
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remove_conflicts(void)
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{
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int i;
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int symbol;
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action *p, *pref = 0;
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SRtotal = 0;
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RRtotal = 0;
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SRconflicts = NEW2(nstates, Value_t);
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RRconflicts = NEW2(nstates, Value_t);
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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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#if defined(YYBTYACC)
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pref = NULL;
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#endif
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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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/* the first parse action for each symbol is the preferred action */
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pref = p;
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symbol = p->symbol;
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}
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/* following conditions handle multiple, i.e., conflicting, parse actions */
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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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StartBacktrack(pref);
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}
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else if (pref != 0 && 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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StartBacktrack(pref);
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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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StartBacktrack(pref);
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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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static void
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total_conflicts(void)
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{
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fprintf(stderr, "%s: ", myname);
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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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if (SRexpect >= 0 && SRtotal != SRexpect)
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{
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fprintf(stderr, "%s: ", myname);
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fprintf(stderr, "expected %d shift/reduce conflict%s.\n",
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SRexpect, PLURAL(SRexpect));
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exit_code = EXIT_FAILURE;
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}
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if (RRexpect >= 0 && RRtotal != RRexpect)
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{
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fprintf(stderr, "%s: ", myname);
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fprintf(stderr, "expected %d reduce/reduce conflict%s.\n",
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RRexpect, PLURAL(RRexpect));
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exit_code = EXIT_FAILURE;
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}
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}
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static int
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sole_reduction(int stateno)
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{
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int count, ruleno;
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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 && MaySuppress(p))
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return (0);
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else if ((p->action_code == REDUCE) && MaySuppress(p))
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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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static void
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defreds(void)
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{
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int i;
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defred = NEW2(nstates, Value_t);
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for (i = 0; i < nstates; i++)
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defred[i] = (Value_t)sole_reduction(i);
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}
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static void
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free_action_row(action *p)
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{
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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
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free_parser(void)
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{
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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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#ifdef NO_LEAKS
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void
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mkpar_leaks(void)
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{
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DO_FREE(defred);
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DO_FREE(rules_used);
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DO_FREE(SRconflicts);
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DO_FREE(RRconflicts);
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}
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#endif
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