tu.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

/* tu.c: draws horizontal lines */
# include "t.h"

void
makeline(int i, int c, int lintype)
{
	int	cr, type, shortl;

	type = thish(i, c);
	if (type == 0) 
		return;
	shortl = (table[i][c].col[0] == '\\');
	if (c > 0 && !shortl && thish(i, c - 1) == type)
		return;
	if (shortl == 0)
		for (cr = c; cr < ncol && (ctype(i, cr) == 's' || type == thish(i, cr)); cr++)
			;
	else
		for (cr = c + 1; cr < ncol && ctype(i, cr) == 's'; cr++)
			;
	drawline(i, c, cr - 1, lintype, 0, shortl);
}


void
fullwide(int i, int lintype)
{
	int	cr, cl;

	if (!pr1403)
		Bprint(&tabout, ".nr %d \\n(.v\n.vs \\n(.vu-\\n(.sp\n", SVS);
	cr = 0;
	while (cr < ncol) {
		cl = cr;
		while (i > 0 && vspand(prev(i), cl, 1))
			cl++;
		for (cr = cl; cr < ncol; cr++)
			if (i > 0 && vspand(prev(i), cr, 1))
				break;
		if (cl < ncol)
			drawline(i, cl, (cr < ncol ? cr - 1 : cr), lintype, 1, 0);
	}
	Bprint(&tabout, "\n");
	if (!pr1403)
		Bprint(&tabout, ".vs \\n(%du\n", SVS);
}


void
drawline(int i, int cl, int cr, int lintype, int noheight, int shortl)
{
	char	*exhr, *exhl, *lnch;
	int	lcount, ln, linpos, oldpos, nodata;

	lcount = 0;
	exhr = exhl = "";
	switch (lintype) {
	case '-': 
		lcount = 1;
		break;
	case '=': 
		lcount = pr1403 ? 1 : 2; 
		break;
	case SHORTLINE: 
		lcount = 1; 
		break;
	}
	if (lcount <= 0) 
		return;
	nodata = cr - cl >= ncol || noheight || allh(i);
	if (!nodata)
		Bprint(&tabout, "\\v'-.5m'");
	for (ln = oldpos = 0; ln < lcount; ln++) {
		linpos = 2 * ln - lcount + 1;
		if (linpos != oldpos)
			Bprint(&tabout, "\\v'%dp'", linpos - oldpos);
		oldpos = linpos;
		if (shortl == 0) {
			tohcol(cl);
			if (lcount > 1) {
				switch (interv(i, cl)) {
				case TOP: 
					exhl = ln == 0 ? "1p" : "-1p"; 
					break;
				case BOT: 
					exhl = ln == 1 ? "1p" : "-1p"; 
					break;
				case THRU: 
					exhl = "1p"; 
					break;
				}
				if (exhl[0])
					Bprint(&tabout, "\\h'%s'", exhl);
			} else if (lcount == 1) {
				switch (interv(i, cl)) {
				case TOP: 
				case BOT: 
					exhl = "-1p"; 
					break;
				case THRU: 
					exhl = "1p"; 
					break;
				}
				if (exhl[0])
					Bprint(&tabout, "\\h'%s'", exhl);
			}
			if (lcount > 1) {
				switch (interv(i, cr + 1)) {
				case TOP: 
					exhr = ln == 0 ? "-1p" : "+1p"; 
					break;
				case BOT: 
					exhr = ln == 1 ? "-1p" : "+1p"; 
					break;
				case THRU: 
					exhr = "-1p"; 
					break;
				}
			} else if (lcount == 1) {
				switch (interv(i, cr + 1)) {
				case TOP: 
				case BOT: 
					exhr = "+1p"; 
					break;
				case THRU: 
					exhr = "-1p"; 
					break;
				}
			}
		} else
			Bprint(&tabout, "\\h'|\\n(%2su'", reg(cl, CLEFT));
		Bprint(&tabout, "\\s\\n(%d", LSIZE);
		if (linsize)
			Bprint(&tabout, "\\v'-\\n(%dp/6u'", LSIZE);
		if (shortl)
			Bprint(&tabout, "\\l'|\\n(%2su'", reg(cr, CRIGHT));
		else
		 {
			lnch = "\\(ul";
			if (pr1403)
				lnch = lintype == 2 ? "=" : "\\(ru";
			if (cr + 1 >= ncol)
				Bprint(&tabout, "\\l'|\\n(TWu%s%s'", exhr, lnch);
			else
				Bprint(&tabout, "\\l'(|\\n(%2su+|\\n(%2su)/2u%s%s'", reg(cr, CRIGHT),
				    reg(cr + 1, CLEFT), exhr, lnch);
		}
		if (linsize)
			Bprint(&tabout, "\\v'\\n(%dp/6u'", LSIZE);
		Bprint(&tabout, "\\s0");
	}
	if (oldpos != 0)
		Bprint(&tabout, "\\v'%dp'", -oldpos);
	if (!nodata)
		Bprint(&tabout, "\\v'+.5m'");
}


void
getstop(void)
{
	int	i, c, k, junk, stopp;

	stopp = 1;
	for (i = 0; i < MAXLIN; i++)
		linestop[i] = 0;
	for (i = 0; i < nlin; i++)
		for (c = 0; c < ncol; c++) {
			k = left(i, c, &junk);
			if (k >= 0 && linestop[k] == 0)
				linestop[k] = ++stopp;
		}
	if (boxflg || allflg || dboxflg)
		linestop[0] = 1;
}


int
left(int i, int c, int *lwidp)
{
	int	kind, li, lj;
					/* returns -1 if no line to left */
					/* returns number of line where it starts */
					/* stores into lwid the kind of line */
	*lwidp = 0;
	if (i < 0) 
		return(-1);
	kind = lefdata(i, c);
	if (kind == 0) 
		return(-1);
	if (i + 1 < nlin)
		if (lefdata(next(i), c) == kind) 
			return(-1);
	li = i;
	while (i >= 0 && lefdata(i, c) == kind)
		i = prev(li = i);
	if (prev(li) == -1) 
		li = 0;
	*lwidp = kind;
	for (lj = i + 1; lj < li; lj++)
		if (instead[lj] && strcmp(instead[lj], ".TH") == 0)
			return(li);
	for (i = i + 1; i < li; i++)
		if (fullbot[i])
			li = i;
	return(li);
}


int
lefdata(int i, int c)
{
	int	ck;

	if (i >= nlin) 
		i = nlin - 1;
	if (ctype(i, c) == 's') {
		for (ck = c; ctype(i, ck) == 's'; ck--)
			;
		if (thish(i, ck) == 0)
			return(0);
	}
	i = stynum[i];
	i = lefline[c][i];
	if (i > 0) 
		return(i);
	if (dboxflg && c == 0) 
		return(2);
	if (allflg)
		return(1);
	if (boxflg && c == 0) 
		return(1);
	return(0);
}


int
next(int i)
{
	while (i + 1 < nlin) {
		i++;
		if (!fullbot[i] && !instead[i]) 
			break;
	}
	return(i);
}


int
prev(int i)
{
	while (--i >= 0  && (fullbot[i] || instead[i]))
		;
	return(i);
}