/*      $OpenBSD: getc.c,v 1.10 2016/01/06 22:28:52 millert Exp $       */

/*-
 * Copyright (c) 1992, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1992, 1993, 1994, 1995, 1996
 *      Keith Bostic.  All rights reserved.
 *
 * See the LICENSE file for redistribution information.
 */

#include "config.h"

#include <sys/types.h>
#include <sys/queue.h>
#include <sys/time.h>

#include <bitstring.h>
#include <ctype.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>

#include "../common/common.h"
#include "vi.h"

/*
 * Character stream routines --
 *      These routines return the file a character at a time.  There are two
 *      special cases.  First, the end of a line, end of a file, start of a
 *      file and empty lines are returned as special cases, and no character
 *      is returned.  Second, empty lines include lines that have only white
 *      space in them, because the vi search functions don't care about white
 *      space, and this makes it easier for them to be consistent.
 */

/*
 * cs_init --
 *      Initialize character stream routines.
 *
 * PUBLIC: int cs_init(SCR *, VCS *);
 */
int
cs_init(SCR *sp, VCS *csp)
{
        int isempty;

        if (db_eget(sp, csp->cs_lno, (char **) &csp->cs_bp, &csp->cs_len,
            &isempty)) {
                if (isempty)
                        msgq(sp, M_BERR, "Empty file");
                return (1);
        }
        if (csp->cs_len == 0 || v_isempty(csp->cs_bp, csp->cs_len)) {
                csp->cs_cno = 0;
                csp->cs_flags = CS_EMP;
        } else {
                csp->cs_flags = 0;
                csp->cs_ch = csp->cs_bp[csp->cs_cno];
        }
        return (0);
}

/*
 * cs_next --
 *      Retrieve the next character.
 *
 * PUBLIC: int cs_next(SCR *, VCS *);
 */
int
cs_next(SCR *sp, VCS *csp)
{
        char *p;

        switch (csp->cs_flags) {
        case CS_EMP:                            /* EMP; get next line. */
        case CS_EOL:                            /* EOL; get next line. */
                if (db_get(sp, ++csp->cs_lno, 0, &p, &csp->cs_len)) {
                        --csp->cs_lno;
                        csp->cs_flags = CS_EOF;
                } else {
                        csp->cs_bp = p;
                        if (csp->cs_len == 0 ||
                            v_isempty(csp->cs_bp, csp->cs_len)) {
                                csp->cs_cno = 0;
                                csp->cs_flags = CS_EMP;
                        } else {
                                csp->cs_flags = 0;
                                csp->cs_ch = csp->cs_bp[csp->cs_cno = 0];
                        }
                }
                break;
        case 0:
                if (csp->cs_cno == csp->cs_len - 1)
                        csp->cs_flags = CS_EOL;
                else
                        csp->cs_ch = csp->cs_bp[++csp->cs_cno];
                break;
        case CS_EOF:                            /* EOF. */
                break;
        default:
                abort();
                /* NOTREACHED */
        }
        return (0);
}

/*
 * cs_fspace --
 *      If on a space, eat forward until something other than a
 *      whitespace character.
 *
 * XXX
 * Semantics of checking the current character were coded for the fword()
 * function -- once the other word routines are converted, they may have
 * to change.
 *
 * PUBLIC: int cs_fspace(SCR *, VCS *);
 */
int
cs_fspace(SCR *sp, VCS *csp)
{
        if (csp->cs_flags != 0 || !isblank(csp->cs_ch))
                return (0);
        for (;;) {
                if (cs_next(sp, csp))
                        return (1);
                if (csp->cs_flags != 0 || !isblank(csp->cs_ch))
                        break;
        }
        return (0);
}

/*
 * cs_fblank --
 *      Eat forward to the next non-whitespace character.
 *
 * PUBLIC: int cs_fblank(SCR *, VCS *);
 */
int
cs_fblank(SCR *sp, VCS *csp)
{
        for (;;) {
                if (cs_next(sp, csp))
                        return (1);
                if (csp->cs_flags == CS_EOL || csp->cs_flags == CS_EMP ||
                    (csp->cs_flags == 0 && isblank(csp->cs_ch)))
                        continue;
                break;
        }
        return (0);
}

/*
 * cs_prev --
 *      Retrieve the previous character.
 *
 * PUBLIC: int cs_prev(SCR *, VCS *);
 */
int
cs_prev(SCR *sp, VCS *csp)
{
        switch (csp->cs_flags) {
        case CS_EMP:                            /* EMP; get previous line. */
        case CS_EOL:                            /* EOL; get previous line. */
                if (csp->cs_lno == 1) {         /* SOF. */
                        csp->cs_flags = CS_SOF;
                        break;
                }
                if (db_get(sp,                  /* The line should exist. */
                    --csp->cs_lno, DBG_FATAL, (char **) &csp->cs_bp,
                    &csp->cs_len)) {
                        ++csp->cs_lno;
                        return (1);
                }
                if (csp->cs_len == 0 || v_isempty(csp->cs_bp, csp->cs_len)) {
                        csp->cs_cno = 0;
                        csp->cs_flags = CS_EMP;
                } else {
                        csp->cs_flags = 0;
                        csp->cs_cno = csp->cs_len - 1;
                        csp->cs_ch = csp->cs_bp[csp->cs_cno];
                }
                break;
        case CS_EOF:                            /* EOF: get previous char. */
        case 0:
                if (csp->cs_cno == 0)
                        if (csp->cs_lno == 1)
                                csp->cs_flags = CS_SOF;
                        else
                                csp->cs_flags = CS_EOL;
                else
                        csp->cs_ch = csp->cs_bp[--csp->cs_cno];
                break;
        case CS_SOF:                            /* SOF. */
                break;
        default:
                abort();
                /* NOTREACHED */
        }
        return (0);
}

/*
 * cs_bblank --
 *      Eat backward to the next non-whitespace character.
 *
 * PUBLIC: int cs_bblank(SCR *, VCS *);
 */
int
cs_bblank(SCR *sp, VCS *csp)
{
        for (;;) {
                if (cs_prev(sp, csp))
                        return (1);
                if (csp->cs_flags == CS_EOL || csp->cs_flags == CS_EMP ||
                    (csp->cs_flags == 0 && isblank(csp->cs_ch)))
                        continue;
                break;
        }
        return (0);
}