/* $OpenBSD: mkpar.c,v 1.19 2017/05/25 20:11:03 tedu Exp $       */
/* $NetBSD: mkpar.c,v 1.4 1996/03/19 03:21:39 jtc Exp $  */

/*
 * 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. 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.
 */

#include "defs.h"

action **parser;
int SRtotal;
int SRexpect = 0;
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(int);
extern action *get_shifts(int);
extern action *add_reductions(int, action *);
extern action *add_reduce(action *, int, int);

short sole_reduction(int);
void free_action_row(action *);

void find_final_state(void);
void unused_rules(void);
void remove_conflicts(void);
void total_conflicts(void);
void defreds(void);


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();
}


action *
parse_actions(int stateno)
{
        action *actions;

        actions = get_shifts(stateno);
        actions = add_reductions(stateno, actions);
        return (actions);
}


action *
get_shifts(int stateno)
{
        action *actions, *temp;
        shifts *sp;
        short *tto_state;
        int i, k;
        int symbol;

        actions = 0;
        sp = shift_table[stateno];
        if (sp) {
                tto_state = sp->shift;
                for (i = sp->nshifts - 1; i >= 0; i--) {
                        k = tto_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(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);
}


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 = 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);
}


void
find_final_state(void)
{
        int goal, i;
        short *tto_state;
        shifts *p;

        p = shift_table[0];
        tto_state = p->shift;
        goal = ritem[1];
        for (i = p->nshifts - 1; i >= 0; --i) {
                final_state = tto_state[i];
                if (accessing_symbol[final_state] == goal)
                        break;
        }
}


void
unused_rules(void)
{
        int i;
        action *p;

        rules_used = calloc(nrules, sizeof(short));
        if (rules_used == NULL)
                no_space();

        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", __progname);
                else
                        fprintf(stderr, "%s: %d rules never reduced\n", __progname,
                                nunused);
        }
}


void
remove_conflicts(void)
{
        int i;
        int symbol;
        action *p, *pref = NULL;

        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;
        }
}


void
total_conflicts(void)
{
        /* Warn if s/r != expect or if any r/r */
        if ((SRtotal != SRexpect) || RRtotal) {
                if (SRtotal == 1)
                        fprintf(stderr, "%s: %s finds 1 shift/reduce conflict\n",
                                input_file_name, __progname);
                else if (SRtotal > 1)
                        fprintf(stderr, "%s: %s finds %d shift/reduce conflicts\n",
                                input_file_name, __progname, SRtotal);
        }
        if (RRtotal == 1)
                fprintf(stderr, "%s: %s finds 1 reduce/reduce conflict\n",
                        input_file_name, __progname);
        else if (RRtotal > 1)
                fprintf(stderr, "%s: %s finds %d reduce/reduce conflicts\n",
                        input_file_name, __progname, RRtotal);
}


short
sole_reduction(int stateno)
{
        int count;
        short ruleno;
        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);
}


void
defreds(void)
{
        int i;

        defred = NEW2(nstates, short);
        for (i = 0; i < nstates; i++)
                defred[i] = sole_reduction(i);
}

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);
}