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rcsid[] and sccsid[] and copyright[] are essentially unmaintained (and
unmaintainable).  these days, people use source.  these id's do not provide
any benefit, and do hurt the small install media
(the 33,000 line diff is essentially mechanical)
ok with the idea millert, ok dms

/*	$OpenBSD: ex_shift.c,v 1.6 2009/10/27 23:59:47 deraadt 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/queue.h>

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

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

enum which {LEFT, RIGHT};
static int shift(SCR *, EXCMD *, enum which);

/*
 * ex_shiftl -- :<[<...]
 *
 *
 * PUBLIC: int ex_shiftl(SCR *, EXCMD *);
 */
int
ex_shiftl(sp, cmdp)
	SCR *sp;
	EXCMD *cmdp;
{
	return (shift(sp, cmdp, LEFT));
}

/*
 * ex_shiftr -- :>[>...]
 *
 * PUBLIC: int ex_shiftr(SCR *, EXCMD *);
 */
int
ex_shiftr(sp, cmdp)
	SCR *sp;
	EXCMD *cmdp;
{
	return (shift(sp, cmdp, RIGHT));
}

/*
 * shift --
 *	Ex shift support.
 */
static int
shift(sp, cmdp, rl)
	SCR *sp;
	EXCMD *cmdp;
	enum which rl;
{
	recno_t from, to;
	size_t blen, len, newcol, newidx, oldcol, oldidx, sw;
	int curset;
	char *p, *bp, *tbp;

	NEEDFILE(sp, cmdp);

	if (O_VAL(sp, O_SHIFTWIDTH) == 0) {
		msgq(sp, M_INFO, "152|shiftwidth option set to 0");
		return (0);
	}

	/* Copy the lines being shifted into the unnamed buffer. */
	if (cut(sp, NULL, &cmdp->addr1, &cmdp->addr2, CUT_LINEMODE))
		return (1);

	/*
	 * The historic version of vi permitted the user to string any number
	 * of '>' or '<' characters together, resulting in an indent of the
	 * appropriate levels.  There's a special hack in ex_cmd() so that
	 * cmdp->argv[0] points to the string of '>' or '<' characters.
	 *
	 * Q: What's the difference between the people adding features
	 *    to vi and the Girl Scouts?
	 * A: The Girl Scouts have mint cookies and adult supervision.
	 */
	for (p = cmdp->argv[0]->bp, sw = 0; *p == '>' || *p == '<'; ++p)
		sw += O_VAL(sp, O_SHIFTWIDTH);

	GET_SPACE_RET(sp, bp, blen, 256);

	curset = 0;
	for (from = cmdp->addr1.lno, to = cmdp->addr2.lno; from <= to; ++from) {
		if (db_get(sp, from, DBG_FATAL, &p, &len))
			goto err;
		if (!len) {
			if (sp->lno == from)
				curset = 1;
			continue;
		}

		/*
		 * Calculate the old indent amount and the number of
		 * characters it used.
		 */
		for (oldidx = 0, oldcol = 0; oldidx < len; ++oldidx)
			if (p[oldidx] == ' ')
				++oldcol;
			else if (p[oldidx] == '\t')
				oldcol += O_VAL(sp, O_TABSTOP) -
				    oldcol % O_VAL(sp, O_TABSTOP);
			else
				break;

		/* Calculate the new indent amount. */
		if (rl == RIGHT)
			newcol = oldcol + sw;
		else {
			newcol = oldcol < sw ? 0 : oldcol - sw;
			if (newcol == oldcol) {
				if (sp->lno == from)
					curset = 1;
				continue;
			}
		}

		/* Get a buffer that will hold the new line. */
		ADD_SPACE_RET(sp, bp, blen, newcol + len);

		/*
		 * Build a new indent string and count the number of
		 * characters it uses.
		 */
		for (tbp = bp, newidx = 0;
		    newcol >= O_VAL(sp, O_TABSTOP); ++newidx) {
			*tbp++ = '\t';
			newcol -= O_VAL(sp, O_TABSTOP);
		}
		for (; newcol > 0; --newcol, ++newidx)
			*tbp++ = ' ';

		/* Add the original line. */
		memcpy(tbp, p + oldidx, len - oldidx);

		/* Set the replacement line. */
		if (db_set(sp, from, bp, (tbp + (len - oldidx)) - bp)) {
err:			FREE_SPACE(sp, bp, blen);
			return (1);
		}

		/*
		 * !!!
		 * The shift command in historic vi had the usual bizarre
		 * collection of cursor semantics.  If called from vi, the
		 * cursor was repositioned to the first non-blank character
		 * of the lowest numbered line shifted.  If called from ex,
		 * the cursor was repositioned to the first non-blank of the
		 * highest numbered line shifted.  Here, if the cursor isn't
		 * part of the set of lines that are moved, move it to the
		 * first non-blank of the last line shifted.  (This makes
		 * ":3>>" in vi work reasonably.)  If the cursor is part of
		 * the shifted lines, it doesn't get moved at all.  This
		 * permits shifting of marked areas, i.e. ">'a." shifts the
		 * marked area twice, something that couldn't be done with
		 * historic vi.
		 */
		if (sp->lno == from) {
			curset = 1;
			if (newidx > oldidx)
				sp->cno += newidx - oldidx;
			else if (sp->cno >= oldidx - newidx)
				sp->cno -= oldidx - newidx;
		}
	}
	if (!curset) {
		sp->lno = to;
		sp->cno = 0;
		(void)nonblank(sp, to, &sp->cno);
	}

	FREE_SPACE(sp, bp, blen);

	sp->rptlines[L_SHIFT] += cmdp->addr2.lno - cmdp->addr1.lno + 1;
	return (0);
}