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Fix the vertical spacing around tbl(7) instances in man(7).

Groff forces the document author to manually request sufficient spacing
after .TE - that is, at least .sp 1v after a table with the "box" option
and at least .sp 2v after a table with the "doublebox" option - or else
it clobbers the box.  I consider that insane, so i'm not imitating groff
in that respect.  Instead, i add at least as much vertical space as groff,
or more where required to avoid clobbering the box.

Consequently, output will be identical for input that looks sane with
groff, and mandoc will make output look better for input that looks bad
with groff.

"Please check them in and I'll look into them later!" kristaps@

/*	$Id: term.c,v 1.202 2012/05/27 18:02:49 schwarze Exp $ */
/*
 * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
 * Copyright (c) 2010, 2011, 2012 Ingo Schwarze <schwarze@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <sys/types.h>

#include <assert.h>
#include <ctype.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "mandoc.h"
#include "out.h"
#include "term.h"
#include "main.h"

static	void		 adjbuf(struct termp *p, int);
static	void		 bufferc(struct termp *, char);
static	void		 encode(struct termp *, const char *, size_t);
static	void		 encode1(struct termp *, int);

void
term_free(struct termp *p)
{

	if (p->buf)
		free(p->buf);
	if (p->symtab)
		mchars_free(p->symtab);

	free(p);
}


void
term_begin(struct termp *p, term_margin head, 
		term_margin foot, const void *arg)
{

	p->headf = head;
	p->footf = foot;
	p->argf = arg;
	(*p->begin)(p);
}


void
term_end(struct termp *p)
{

	(*p->end)(p);
}

/*
 * Flush a line of text.  A "line" is loosely defined as being something
 * that should be followed by a newline, regardless of whether it's
 * broken apart by newlines getting there.  A line can also be a
 * fragment of a columnar list (`Bl -tag' or `Bl -column'), which does
 * not have a trailing newline.
 *
 * The following flags may be specified:
 *
 *  - TERMP_NOBREAK: this is the most important and is used when making
 *    columns.  In short: don't print a newline and instead expect the
 *    next call to do the padding up to the start of the next column.
 *
 *  - TERMP_TWOSPACE: make sure there is room for at least two space
 *    characters of padding.  Otherwise, rather break the line.
 *
 *  - TERMP_DANGLE: don't newline when TERMP_NOBREAK is specified and
 *    the line is overrun, and don't pad-right if it's underrun.
 *
 *  - TERMP_HANG: like TERMP_DANGLE, but doesn't newline when
 *    overrunning, instead save the position and continue at that point
 *    when the next invocation.
 *
 *  In-line line breaking:
 *
 *  If TERMP_NOBREAK is specified and the line overruns the right
 *  margin, it will break and pad-right to the right margin after
 *  writing.  If maxrmargin is violated, it will break and continue
 *  writing from the right-margin, which will lead to the above scenario
 *  upon exit.  Otherwise, the line will break at the right margin.
 */
void
term_flushln(struct termp *p)
{
	int		 i;     /* current input position in p->buf */
	size_t		 vis;   /* current visual position on output */
	size_t		 vbl;   /* number of blanks to prepend to output */
	size_t		 vend;	/* end of word visual position on output */
	size_t		 bp;    /* visual right border position */
	size_t		 dv;    /* temporary for visual pos calculations */
	int		 j;     /* temporary loop index for p->buf */
	int		 jhy;	/* last hyph before overflow w/r/t j */
	size_t		 maxvis; /* output position of visible boundary */
	size_t		 mmax; /* used in calculating bp */

	/*
	 * First, establish the maximum columns of "visible" content.
	 * This is usually the difference between the right-margin and
	 * an indentation, but can be, for tagged lists or columns, a
	 * small set of values. 
	 */
	assert  (p->rmargin >= p->offset);
	dv     = p->rmargin - p->offset;
	maxvis = (int)dv > p->overstep ? dv - (size_t)p->overstep : 0;
	dv     = p->maxrmargin - p->offset;
	mmax   = (int)dv > p->overstep ? dv - (size_t)p->overstep : 0;

	bp = TERMP_NOBREAK & p->flags ? mmax : maxvis;

	/*
	 * Calculate the required amount of padding.
	 */
	vbl = p->offset + p->overstep > p->viscol ?
	      p->offset + p->overstep - p->viscol : 0;

	vis = vend = 0;
	i = 0;

	while (i < p->col) {
		/*
		 * Handle literal tab characters: collapse all
		 * subsequent tabs into a single huge set of spaces.
		 */
		while (i < p->col && '\t' == p->buf[i]) {
			vend = (vis / p->tabwidth + 1) * p->tabwidth;
			vbl += vend - vis;
			vis = vend;
			i++;
		}

		/*
		 * Count up visible word characters.  Control sequences
		 * (starting with the CSI) aren't counted.  A space
		 * generates a non-printing word, which is valid (the
		 * space is printed according to regular spacing rules).
		 */

		for (j = i, jhy = 0; j < p->col; j++) {
			if ((j && ' ' == p->buf[j]) || '\t' == p->buf[j])
				break;

			/* Back over the the last printed character. */
			if (8 == p->buf[j]) {
				assert(j);
				vend -= (*p->width)(p, p->buf[j - 1]);
				continue;
			}

			/* Regular word. */
			/* Break at the hyphen point if we overrun. */
			if (vend > vis && vend < bp && 
					ASCII_HYPH == p->buf[j])
				jhy = j;

			vend += (*p->width)(p, p->buf[j]);
		}

		/*
		 * Find out whether we would exceed the right margin.
		 * If so, break to the next line.
		 */
		if (vend > bp && 0 == jhy && vis > 0) {
			vend -= vis;
			(*p->endline)(p);
			p->viscol = 0;
			if (TERMP_NOBREAK & p->flags) {
				vbl = p->rmargin;
				vend += p->rmargin - p->offset;
			} else
				vbl = p->offset;

			/* Remove the p->overstep width. */

			bp += (size_t)p->overstep;
			p->overstep = 0;
		}

		/* Write out the [remaining] word. */
		for ( ; i < p->col; i++) {
			if (vend > bp && jhy > 0 && i > jhy)
				break;
			if ('\t' == p->buf[i])
				break;
			if (' ' == p->buf[i]) {
				j = i;
				while (' ' == p->buf[i])
					i++;
				dv = (size_t)(i - j) * (*p->width)(p, ' ');
				vbl += dv;
				vend += dv;
				break;
			}
			if (ASCII_NBRSP == p->buf[i]) {
				vbl += (*p->width)(p, ' ');
				continue;
			}

			/*
			 * Now we definitely know there will be
			 * printable characters to output,
			 * so write preceding white space now.
			 */
			if (vbl) {
				(*p->advance)(p, vbl);
				p->viscol += vbl;
				vbl = 0;
			}

			if (ASCII_HYPH == p->buf[i]) {
				(*p->letter)(p, '-');
				p->viscol += (*p->width)(p, '-');
				continue;
			}

			(*p->letter)(p, p->buf[i]);
			if (8 == p->buf[i])
				p->viscol -= (*p->width)(p, p->buf[i-1]);
			else 
				p->viscol += (*p->width)(p, p->buf[i]);
		}
		vis = vend;
	}

	/*
	 * If there was trailing white space, it was not printed;
	 * so reset the cursor position accordingly.
	 */
	if (vis)
		vis -= vbl;

	p->col = 0;
	p->overstep = 0;

	if ( ! (TERMP_NOBREAK & p->flags)) {
		p->viscol = 0;
		(*p->endline)(p);
		return;
	}

	if (TERMP_HANG & p->flags) {
		/* We need one blank after the tag. */
		p->overstep = (int)(vis - maxvis + (*p->width)(p, ' '));

		/*
		 * Behave exactly the same way as groff:
		 * If we have overstepped the margin, temporarily move
		 * it to the right and flag the rest of the line to be
		 * shorter.
		 * If we landed right at the margin, be happy.
		 * If we are one step before the margin, temporarily
		 * move it one step LEFT and flag the rest of the line
		 * to be longer.
		 */
		if (p->overstep < -1)
			p->overstep = 0;
		return;

	} else if (TERMP_DANGLE & p->flags)
		return;

	/* If the column was overrun, break the line. */
	if (maxvis <= vis +
	    ((TERMP_TWOSPACE & p->flags) ? (*p->width)(p, ' ') : 0)) {
		(*p->endline)(p);
		p->viscol = 0;
	}
}


/* 
 * A newline only breaks an existing line; it won't assert vertical
 * space.  All data in the output buffer is flushed prior to the newline
 * assertion.
 */
void
term_newln(struct termp *p)
{

	p->flags |= TERMP_NOSPACE;
	if (p->col || p->viscol)
		term_flushln(p);
}


/*
 * Asserts a vertical space (a full, empty line-break between lines).
 * Note that if used twice, this will cause two blank spaces and so on.
 * All data in the output buffer is flushed prior to the newline
 * assertion.
 */
void
term_vspace(struct termp *p)
{

	term_newln(p);
	p->viscol = 0;
	if (0 < p->skipvsp)
		p->skipvsp--;
	else
		(*p->endline)(p);
}

void
term_fontlast(struct termp *p)
{
	enum termfont	 f;

	f = p->fontl;
	p->fontl = p->fontq[p->fonti];
	p->fontq[p->fonti] = f;
}


void
term_fontrepl(struct termp *p, enum termfont f)
{

	p->fontl = p->fontq[p->fonti];
	p->fontq[p->fonti] = f;
}


void
term_fontpush(struct termp *p, enum termfont f)
{

	assert(p->fonti + 1 < 10);
	p->fontl = p->fontq[p->fonti];
	p->fontq[++p->fonti] = f;
}


const void *
term_fontq(struct termp *p)
{

	return(&p->fontq[p->fonti]);
}


enum termfont
term_fonttop(struct termp *p)
{

	return(p->fontq[p->fonti]);
}


void
term_fontpopq(struct termp *p, const void *key)
{

	while (p->fonti >= 0 && key != &p->fontq[p->fonti])
		p->fonti--;
	assert(p->fonti >= 0);
}


void
term_fontpop(struct termp *p)
{

	assert(p->fonti);
	p->fonti--;
}

/*
 * Handle pwords, partial words, which may be either a single word or a
 * phrase that cannot be broken down (such as a literal string).  This
 * handles word styling.
 */
void
term_word(struct termp *p, const char *word)
{
	const char	*seq, *cp;
	char		 c;
	int		 sz, uc;
	size_t		 ssz;
	enum mandoc_esc	 esc;

	if ( ! (TERMP_NOSPACE & p->flags)) {
		if ( ! (TERMP_KEEP & p->flags)) {
			if (TERMP_PREKEEP & p->flags)
				p->flags |= TERMP_KEEP;
			bufferc(p, ' ');
			if (TERMP_SENTENCE & p->flags)
				bufferc(p, ' ');
		} else
			bufferc(p, ASCII_NBRSP);
	}

	if ( ! (p->flags & TERMP_NONOSPACE))
		p->flags &= ~TERMP_NOSPACE;
	else
		p->flags |= TERMP_NOSPACE;

	p->flags &= ~(TERMP_SENTENCE | TERMP_IGNDELIM);

	while ('\0' != *word) {
		if ((ssz = strcspn(word, "\\")) > 0)
			encode(p, word, ssz);

		word += (int)ssz;
		if ('\\' != *word)
			continue;

		word++;
		esc = mandoc_escape(&word, &seq, &sz);
		if (ESCAPE_ERROR == esc)
			break;

		if (TERMENC_ASCII != p->enc)
			switch (esc) {
			case (ESCAPE_UNICODE):
				uc = mchars_num2uc(seq + 1, sz - 1);
				if ('\0' == uc)
					break;
				encode1(p, uc);
				continue;
			case (ESCAPE_SPECIAL):
				uc = mchars_spec2cp(p->symtab, seq, sz);
				if (uc <= 0)
					break;
				encode1(p, uc);
				continue;
			default:
				break;
			}

		switch (esc) {
		case (ESCAPE_UNICODE):
			encode1(p, '?');
			break;
		case (ESCAPE_NUMBERED):
			c = mchars_num2char(seq, sz);
			if ('\0' != c)
				encode(p, &c, 1);
			break;
		case (ESCAPE_SPECIAL):
			cp = mchars_spec2str(p->symtab, seq, sz, &ssz);
			if (NULL != cp) 
				encode(p, cp, ssz);
			else if (1 == ssz)
				encode(p, seq, sz);
			break;
		case (ESCAPE_FONTBOLD):
			term_fontrepl(p, TERMFONT_BOLD);
			break;
		case (ESCAPE_FONTITALIC):
			term_fontrepl(p, TERMFONT_UNDER);
			break;
		case (ESCAPE_FONT):
			/* FALLTHROUGH */
		case (ESCAPE_FONTROMAN):
			term_fontrepl(p, TERMFONT_NONE);
			break;
		case (ESCAPE_FONTPREV):
			term_fontlast(p);
			break;
		case (ESCAPE_NOSPACE):
			if ('\0' == *word)
				p->flags |= TERMP_NOSPACE;
			break;
		default:
			break;
		}
	}
}

static void
adjbuf(struct termp *p, int sz)
{

	if (0 == p->maxcols)
		p->maxcols = 1024;
	while (sz >= p->maxcols)
		p->maxcols <<= 2;

	p->buf = mandoc_realloc
		(p->buf, sizeof(int) * (size_t)p->maxcols);
}

static void
bufferc(struct termp *p, char c)
{

	if (p->col + 1 >= p->maxcols)
		adjbuf(p, p->col + 1);

	p->buf[p->col++] = c;
}

/*
 * See encode().
 * Do this for a single (probably unicode) value.
 * Does not check for non-decorated glyphs.
 */
static void
encode1(struct termp *p, int c)
{
	enum termfont	  f;

	if (p->col + 4 >= p->maxcols)
		adjbuf(p, p->col + 4);

	f = term_fonttop(p);

	if (TERMFONT_NONE == f) {
		p->buf[p->col++] = c;
		return;
	} else if (TERMFONT_UNDER == f) {
		p->buf[p->col++] = '_';
	} else
		p->buf[p->col++] = c;

	p->buf[p->col++] = 8;
	p->buf[p->col++] = c;
}

static void
encode(struct termp *p, const char *word, size_t sz)
{
	enum termfont	  f;
	int		  i, len;

	/* LINTED */
	len = sz;

	/*
	 * Encode and buffer a string of characters.  If the current
	 * font mode is unset, buffer directly, else encode then buffer
	 * character by character.
	 */

	if (TERMFONT_NONE == (f = term_fonttop(p))) {
		if (p->col + len >= p->maxcols) 
			adjbuf(p, p->col + len);
		for (i = 0; i < len; i++)
			p->buf[p->col++] = word[i];
		return;
	}

	/* Pre-buffer, assuming worst-case. */

	if (p->col + 1 + (len * 3) >= p->maxcols)
		adjbuf(p, p->col + 1 + (len * 3));

	for (i = 0; i < len; i++) {
		if (ASCII_HYPH != word[i] &&
		    ! isgraph((unsigned char)word[i])) {
			p->buf[p->col++] = word[i];
			continue;
		}

		if (TERMFONT_UNDER == f)
			p->buf[p->col++] = '_';
		else if (ASCII_HYPH == word[i])
			p->buf[p->col++] = '-';
		else
			p->buf[p->col++] = word[i];

		p->buf[p->col++] = 8;
		p->buf[p->col++] = word[i];
	}
}

size_t
term_len(const struct termp *p, size_t sz)
{

	return((*p->width)(p, ' ') * sz);
}


size_t
term_strlen(const struct termp *p, const char *cp)
{
	size_t		 sz, rsz, i;
	int		 ssz, c;
	const char	*seq, *rhs;
	enum mandoc_esc	 esc;
	static const char rej[] = { '\\', ASCII_HYPH, ASCII_NBRSP, '\0' };

	/*
	 * Account for escaped sequences within string length
	 * calculations.  This follows the logic in term_word() as we
	 * must calculate the width of produced strings.
	 */

	sz = 0;
	while ('\0' != *cp) {
		rsz = strcspn(cp, rej);
		for (i = 0; i < rsz; i++)
			sz += (*p->width)(p, *cp++);

		c = 0;
		switch (*cp) {
		case ('\\'):
			cp++;
			esc = mandoc_escape(&cp, &seq, &ssz);
			if (ESCAPE_ERROR == esc)
				return(sz);

			if (TERMENC_ASCII != p->enc)
				switch (esc) {
				case (ESCAPE_UNICODE):
					c = mchars_num2uc
						(seq + 1, ssz - 1);
					if ('\0' == c)
						break;
					sz += (*p->width)(p, c);
					continue;
				case (ESCAPE_SPECIAL):
					c = mchars_spec2cp
						(p->symtab, seq, ssz);
					if (c <= 0)
						break;
					sz += (*p->width)(p, c);
					continue;
				default:
					break;
				}

			rhs = NULL;

			switch (esc) {
			case (ESCAPE_UNICODE):
				sz += (*p->width)(p, '?');
				break;
			case (ESCAPE_NUMBERED):
				c = mchars_num2char(seq, ssz);
				if ('\0' != c)
					sz += (*p->width)(p, c);
				break;
			case (ESCAPE_SPECIAL):
				rhs = mchars_spec2str
					(p->symtab, seq, ssz, &rsz);

				if (ssz != 1 || rhs)
					break;

				rhs = seq;
				rsz = ssz;
				break;
			default:
				break;
			}

			if (NULL == rhs)
				break;

			for (i = 0; i < rsz; i++)
				sz += (*p->width)(p, *rhs++);
			break;
		case (ASCII_NBRSP):
			sz += (*p->width)(p, ' ');
			cp++;
			break;
		case (ASCII_HYPH):
			sz += (*p->width)(p, '-');
			cp++;
			break;
		default:
			break;
		}
	}

	return(sz);
}

/* ARGSUSED */
size_t
term_vspan(const struct termp *p, const struct roffsu *su)
{
	double		 r;

	switch (su->unit) {
	case (SCALE_CM):
		r = su->scale * 2;
		break;
	case (SCALE_IN):
		r = su->scale * 6;
		break;
	case (SCALE_PC):
		r = su->scale;
		break;
	case (SCALE_PT):
		r = su->scale / 8;
		break;
	case (SCALE_MM):
		r = su->scale / 1000;
		break;
	case (SCALE_VS):
		r = su->scale;
		break;
	default:
		r = su->scale - 1;
		break;
	}

	if (r < 0.0)
		r = 0.0;
	return(/* LINTED */(size_t)
			r);
}

size_t
term_hspan(const struct termp *p, const struct roffsu *su)
{
	double		 v;

	v = ((*p->hspan)(p, su));
	if (v < 0.0)
		v = 0.0;
	return((size_t) /* LINTED */
			v);
}