/*      $NetBSD: parse.c,v 1.85 2025/01/07 03:55:00 rillig Exp $        */

/*-
 * SPDX-License-Identifier: BSD-4-Clause
 *
 * Copyright (c) 1985 Sun Microsystems, Inc.
 * Copyright (c) 1980, 1993
 *      The Regents of the University of California.  All rights reserved.
 * All rights reserved.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. 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 <sys/cdefs.h>
__RCSID("$NetBSD: parse.c,v 1.85 2025/01/07 03:55:00 rillig Exp $");

#include <stdlib.h>

#include "indent.h"

/* Replace the top 2 symbols with the given symbol. */
static void
ps_psyms_replace2(parser_symbol psym)
{
        ps.psyms.len--;
        ps.psyms.sym[ps.psyms.len - 1] = psym;
        ps.ind_level_follow = ps.psyms.ind_level[ps.psyms.len - 1];
}

static int
left_justify_decl_level(void)
{
        int level = 0;
        for (size_t i = ps.psyms.len - 2; i > 0; i--)
                if (ps.psyms.sym[i] == psym_decl)
                        level++;
        return level;
}

void
ps_psyms_push(parser_symbol psym, int ind_level)
{
        if (ps.psyms.len == ps.psyms.cap) {
                ps.psyms.cap += 16;
                ps.psyms.sym = nonnull(realloc(ps.psyms.sym,
                        sizeof(ps.psyms.sym[0]) * ps.psyms.cap));
                ps.psyms.ind_level = nonnull(realloc(ps.psyms.ind_level,
                        sizeof(ps.psyms.ind_level[0]) * ps.psyms.cap));
        }
        ps.psyms.len++;
        ps.psyms.sym[ps.psyms.len - 1] = psym;
        ps.psyms.ind_level[ps.psyms.len - 1] = ind_level;
}

/*
 * Repeatedly try to reduce the top two symbols on the parse stack to a single
 * symbol, until no more reductions are possible.
 */
static void
psyms_reduce(void)
{
again:
        if (ps.psyms.len >= 2 && ps.psyms.sym[ps.psyms.len - 1] == psym_stmt) {
                switch (ps.psyms.sym[ps.psyms.len - 2]) {
                case psym_decl:
                case psym_stmt:
                case psym_for_exprs:
                case psym_if_expr_stmt_else:
                case psym_switch_expr:
                case psym_while_expr:
                        ps_psyms_replace2(psym_stmt);
                        goto again;
                case psym_if_expr:
                        ps_psyms_replace2(psym_if_expr_stmt);
                        goto again;
                case psym_do:
                        ps_psyms_replace2(psym_do_stmt);
                        goto again;
                default:
                        return;
                }
        }
        if (ps.psyms.sym[ps.psyms.len - 1] == psym_while_expr &&
            ps.psyms.sym[ps.psyms.len - 2] == psym_do_stmt) {
                ps.psyms.len -= 2;
                goto again;
        }
}

static bool
is_lbrace(parser_symbol psym)
{
        return psym == psym_lbrace_block
            || psym == psym_lbrace_struct
            || psym == psym_lbrace_union
            || psym == psym_lbrace_enum;
}

/*
 * Shift the token onto the parser stack, then try to reduce it by combining it with
 * previous tokens.
 */
void
parse(parser_symbol psym)
{
        debug_blank_line();
        debug_println("parse: %s", psym_name[psym]);

        if (psym != psym_else) {
                while (ps.psyms.sym[ps.psyms.len - 1] == psym_if_expr_stmt) {
                        ps.psyms.sym[ps.psyms.len - 1] = psym_stmt;
                        psyms_reduce();
                        ps.ind_level = ps.ind_level_follow
                            = ps.psyms.ind_level[ps.psyms.len - 1];
                }
        }

        switch (psym) {

        case psym_lbrace_block:
        case psym_lbrace_struct:
        case psym_lbrace_union:
        case psym_lbrace_enum:
                ps.break_after_comma = false;
                if (ps.psyms.sym[ps.psyms.len - 1] == psym_decl
                    || ps.psyms.sym[ps.psyms.len - 1] == psym_stmt)
                        ps.ind_level_follow++;
                else if (code.len == 0) {
                        /* It is part of a while, for, etc. */
                        ps.ind_level--;

                        /* for a switch, brace should be two levels out from
                         * the code */
                        if (ps.psyms.sym[ps.psyms.len - 1] == psym_switch_expr
                            && opt.case_indent >= 1.0F)
                                ps.ind_level--;
                }

                ps_psyms_push(psym, ps.ind_level);
                ps_psyms_push(psym_stmt, ps.ind_level_follow);
                break;

        case psym_rbrace:
                /* stack should have <lbrace> <stmt> or <lbrace> <decl> */
                if (!(ps.psyms.len >= 2
                        && is_lbrace(ps.psyms.sym[ps.psyms.len - 2]))) {
                        diag(1, "Statement nesting error");
                        break;
                }
                ps_psyms_replace2(psym_stmt);
                ps.ind_level = ps.ind_level_follow;
                break;

        case psym_decl:
                if (ps.psyms.sym[ps.psyms.len - 1] == psym_decl)
                        break;  /* only put one declaration onto stack */

                ps.break_after_comma = true;
                ps_psyms_push(psym_decl, ps.ind_level_follow);

                if (opt.left_justify_decl) {
                        ps.ind_level = left_justify_decl_level();
                        ps.ind_level_follow = ps.ind_level;
                }
                break;

        case psym_stmt:
                ps.break_after_comma = false;
                ps_psyms_push(psym_stmt, ps.ind_level);
                break;

        case psym_if_expr:
                if (ps.psyms.sym[ps.psyms.len - 1] == psym_if_expr_stmt_else
                    && opt.else_if_in_same_line) {
                        ps.ind_level_follow =
                            ps.psyms.ind_level[ps.psyms.len - 1];
                        ps.psyms.len--;
                }
                /* FALLTHROUGH */
        case psym_do:
        case psym_for_exprs:
                ps.ind_level = ps.ind_level_follow;
                ps.ind_level_follow = ps.ind_level + 1;
                ps_psyms_push(psym, ps.ind_level);
                break;

        case psym_else:
                if (ps.psyms.sym[ps.psyms.len - 1] != psym_if_expr_stmt) {
                        diag(1, "Unmatched 'else'");
                        break;
                }
                ps.ind_level = ps.psyms.ind_level[ps.psyms.len - 1];
                ps.ind_level_follow = ps.ind_level + 1;
                ps.psyms.sym[ps.psyms.len - 1] = psym_if_expr_stmt_else;
                break;

        case psym_switch_expr:
                ps_psyms_push(psym_switch_expr, ps.ind_level_follow);
                ps.ind_level_follow += (int)opt.case_indent + 1;
                break;

        case psym_while_expr:
                if (ps.psyms.sym[ps.psyms.len - 1] == psym_do_stmt) {
                        ps.ind_level = ps.psyms.ind_level[ps.psyms.len - 1];
                        ps.ind_level_follow = ps.ind_level;
                        ps_psyms_push(psym_while_expr, ps.ind_level);
                } else {
                        ps_psyms_push(psym_while_expr, ps.ind_level_follow);
                        ps.ind_level_follow++;
                }
                break;

        default:
                diag(1, "Unknown code to parser");
                return;
        }

#if debug
        static struct buffer before, after;
        buf_clear(&before);
        ps_psyms_to_string(&before, &ps);
#endif
        psyms_reduce();
#if debug
        buf_clear(&after);
        ps_psyms_to_string(&after, &ps);
        if (strcmp(before.s, after.s) != 0) {
                debug_println("psyms before: %s", before.s);
                debug_println("psyms after:  %s", after.s);
        } else
                debug_println("psyms: %s", after.s);
#endif
}