xec.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

#include "sam.h"
#include "parse.h"

int	Glooping;
int	nest;

int	append(File*, Cmd*, Posn);
int	display(File*);
void	looper(File*, Cmd*, int);
void	filelooper(Cmd*, int);
void	linelooper(File*, Cmd*);

void
resetxec(void)
{
	Glooping = nest = 0;
}

int
cmdexec(File *f, Cmd *cp)
{
	int i;
	Addr *ap;
	Address a;

	if(f && f->unread)
		load(f);
	if(f==0 && (cp->addr==0 || cp->addr->type!='"') &&
	    !utfrune("bBnqUXY!", cp->cmdc) &&
	    cp->cmdc!=('c'|0x100) && !(cp->cmdc=='D' && cp->ctext))
		error(Enofile);
	i = lookup(cp->cmdc);
	if(i >= 0 && cmdtab[i].defaddr != aNo){
		if((ap=cp->addr)==0 && cp->cmdc!='\n'){
			cp->addr = ap = newaddr();
			ap->type = '.';
			if(cmdtab[i].defaddr == aAll)
				ap->type = '*';
		}else if(ap && ap->type=='"' && ap->next==0 && cp->cmdc!='\n'){
			ap->next = newaddr();
			ap->next->type = '.';
			if(cmdtab[i].defaddr == aAll)
				ap->next->type = '*';
		}
		if(cp->addr){	/* may be false for '\n' (only) */
			static Address none = {0,0,0};
			if(f)
				addr = address(ap, f->dot, 0);
			else	/* a " */
				addr = address(ap, none, 0);
			f = addr.f;
		}
	}
	current(f);
	switch(cp->cmdc){
	case '{':
		a = cp->addr? address(cp->addr, f->dot, 0): f->dot;
		for(cp = cp->ccmd; cp; cp = cp->next){
			a.f->dot = a;
			cmdexec(a.f, cp);
		}
		break;
	default:
		i=(*cmdtab[i].fn)(f, cp);
		return i;
	}
	return 1;
}


int
a_cmd(File *f, Cmd *cp)
{
	return append(f, cp, addr.r.p2);
}

int
b_cmd(File *f, Cmd *cp)
{
	USED(f);
	f = cp->cmdc=='b'? tofile(cp->ctext) : getfile(cp->ctext);
	if(f->unread)
		load(f);
	else if(nest == 0)
		filename(f);
	return TRUE;
}

int
c_cmd(File *f, Cmd *cp)
{
	logdelete(f, addr.r.p1, addr.r.p2);
	f->ndot.r.p1 = f->ndot.r.p2 = addr.r.p2;
	return append(f, cp, addr.r.p2);
}

int
d_cmd(File *f, Cmd *cp)
{
	USED(cp);
	logdelete(f, addr.r.p1, addr.r.p2);
	f->ndot.r.p1 = f->ndot.r.p2 = addr.r.p1;
	return TRUE;
}

int
D_cmd(File *f, Cmd *cp)
{
	closefiles(f, cp->ctext);
	return TRUE;
}

int
e_cmd(File *f, Cmd *cp)
{
	if(getname(f, cp->ctext, cp->cmdc=='e')==0)
		error(Enoname);
	edit(f, cp->cmdc);
	return TRUE;
}

int
f_cmd(File *f, Cmd *cp)
{
	getname(f, cp->ctext, TRUE);
	filename(f);
	return TRUE;
}

int
g_cmd(File *f, Cmd *cp)
{
	if(f!=addr.f)panic("g_cmd f!=addr.f");
	compile(cp->re);
	if(execute(f, addr.r.p1, addr.r.p2) ^ cp->cmdc=='v'){
		f->dot = addr;
		return cmdexec(f, cp->ccmd);
	}
	return TRUE;
}

int
i_cmd(File *f, Cmd *cp)
{
	return append(f, cp, addr.r.p1);
}

int
k_cmd(File *f, Cmd *cp)
{
	USED(cp);
	f->mark = addr.r;
	return TRUE;
}

int
m_cmd(File *f, Cmd *cp)
{
	Address addr2;

	addr2 = address(cp->caddr, f->dot, 0);
	if(cp->cmdc=='m')
		move(f, addr2);
	else
		copy(f, addr2);
	return TRUE;
}

int
n_cmd(File *f, Cmd *cp)
{
	int i;
	USED(f);
	USED(cp);
	for(i = 0; i<file.nused; i++){
		if(file.filepptr[i] == cmd)
			continue;
		f = file.filepptr[i];
		Strduplstr(&genstr, &f->name);
		filename(f);
	}
	return TRUE;
}

int
p_cmd(File *f, Cmd *cp)
{
	USED(cp);
	return display(f);
}

int
q_cmd(File *f, Cmd *cp)
{
	USED(cp);
	USED(f);
	trytoquit();
	if(downloaded){
		outT0(Hexit);
		return TRUE;
	}
	return FALSE;
}

int
s_cmd(File *f, Cmd *cp)
{
	int i, j, c, n;
	Posn p1, op, didsub = 0, delta = 0;

	n = cp->num;
	op= -1;
	compile(cp->re);
	for(p1 = addr.r.p1; p1<=addr.r.p2 && execute(f, p1, addr.r.p2); ){
		if(sel.p[0].p1==sel.p[0].p2){	/* empty match? */
			if(sel.p[0].p1==op){
				p1++;
				continue;
			}
			p1 = sel.p[0].p2+1;
		}else
			p1 = sel.p[0].p2;
		op = sel.p[0].p2;
		if(--n>0)
			continue;
		Strzero(&genstr);
		for(i = 0; i<cp->ctext->n; i++)
			if((c = cp->ctext->s[i])=='\\' && i<cp->ctext->n-1){
				c = cp->ctext->s[++i];
				if('1'<=c && c<='9') {
					j = c-'0';
					if(sel.p[j].p2-sel.p[j].p1>BLOCKSIZE)
						error(Elongtag);
					bufread(f, sel.p[j].p1, genbuf, sel.p[j].p2-sel.p[j].p1);
					Strinsert(&genstr, tmprstr(genbuf, (sel.p[j].p2-sel.p[j].p1)), genstr.n);
				}else
				 	Straddc(&genstr, c);
			}else if(c!='&')
				Straddc(&genstr, c);
			else{
				if(sel.p[0].p2-sel.p[0].p1>BLOCKSIZE)
					error(Elongrhs);
				bufread(f, sel.p[0].p1, genbuf, sel.p[0].p2-sel.p[0].p1);
				Strinsert(&genstr,
					tmprstr(genbuf, (int)(sel.p[0].p2-sel.p[0].p1)),
					genstr.n);
			}
		if(sel.p[0].p1!=sel.p[0].p2){
			logdelete(f, sel.p[0].p1, sel.p[0].p2);
			delta-=sel.p[0].p2-sel.p[0].p1;
		}
		if(genstr.n){
			loginsert(f, sel.p[0].p2, genstr.s, genstr.n);
			delta+=genstr.n;
		}
		didsub = 1;
		if(!cp->flag)
			break;
	}
	if(!didsub && nest==0)
		error(Enosub);
	f->ndot.r.p1 = addr.r.p1, f->ndot.r.p2 = addr.r.p2+delta;
	return TRUE;
}

int
u_cmd(File *f, Cmd *cp)
{
	int n;

	USED(f);
	USED(cp);
	n = cp->num;
	if(n >= 0)
		while(n-- && undo(TRUE))
			;
	else
		while(n++ && undo(FALSE))
			;
	return TRUE;
}

int
w_cmd(File *f, Cmd *cp)
{
	int fseq;

	fseq = f->seq;
	if(getname(f, cp->ctext, FALSE)==0)
		error(Enoname);
	if(fseq == seq)
		error_s(Ewseq, genc);
	writef(f);
	return TRUE;
}

int
x_cmd(File *f, Cmd *cp)
{
	if(cp->re)
		looper(f, cp, cp->cmdc=='x');
	else
		linelooper(f, cp);
	return TRUE;
}

int
X_cmd(File *f, Cmd *cp)
{
	USED(f);
	filelooper(cp, cp->cmdc=='X');
	return TRUE;
}

int
plan9_cmd(File *f, Cmd *cp)
{
	plan9(f, cp->cmdc, cp->ctext, nest);
	return TRUE;
}

int
eq_cmd(File *f, Cmd *cp)
{
	int charsonly;

	switch(cp->ctext->n){
	case 1:
		charsonly = FALSE;
		break;
	case 2:
		if(cp->ctext->s[0]=='#'){
			charsonly = TRUE;
			break;
		}
	default:
		SET(charsonly);
		error(Enewline);
	}
	printposn(f, charsonly);
	return TRUE;
}

int
nl_cmd(File *f, Cmd *cp)
{
	Address a;

	if(cp->addr == 0){
		/* First put it on newline boundaries */
		addr = lineaddr((Posn)0, f->dot, -1);
		a = lineaddr((Posn)0, f->dot, 1);
		addr.r.p2 = a.r.p2;
		if(addr.r.p1==f->dot.r.p1 && addr.r.p2==f->dot.r.p2)
			addr = lineaddr((Posn)1, f->dot, 1);
		display(f);
	}else if(downloaded)
		moveto(f, addr.r);
	else
		display(f);
	return TRUE;
}

int
cd_cmd(File *f, Cmd *cp)
{
	USED(f);
	cd(cp->ctext);
	return TRUE;
}

int
append(File *f, Cmd *cp, Posn p)
{
	if(cp->ctext->n>0 && cp->ctext->s[cp->ctext->n-1]==0)
		--cp->ctext->n;
	if(cp->ctext->n>0)
		loginsert(f, p, cp->ctext->s, cp->ctext->n);
	f->ndot.r.p1 = p;
	f->ndot.r.p2 = p+cp->ctext->n;
	return TRUE;
}

int
display(File *f)
{
	Posn p1, p2;
	int np;
	char *c;

	p1 = addr.r.p1;
	p2 = addr.r.p2;
	if(p2 > f->nc){
		fprint(2, "bad display addr p1=%ld p2=%ld f->nc=%d\n", p1, p2, f->nc); /*ZZZ should never happen, can remove */
		p2 = f->nc;
	}
	while(p1 < p2){
		np = p2-p1;
		if(np>BLOCKSIZE-1)
			np = BLOCKSIZE-1;
		bufread(f, p1, genbuf, np);
		genbuf[np] = 0;
		c = Strtoc(tmprstr(genbuf, np+1));
		if(downloaded)
			termwrite(c);
		else
			Write(1, c, strlen(c));
		free(c);
		p1 += np;
	}
	f->dot = addr;
	return TRUE;
}

void
looper(File *f, Cmd *cp, int xy)
{
	Posn p, op;
	Range r;

	r = addr.r;
	op= xy? -1 : r.p1;
	nest++;
	compile(cp->re);
	for(p = r.p1; p<=r.p2; ){
		if(!execute(f, p, r.p2)){ /* no match, but y should still run */
			if(xy || op>r.p2)
				break;
			f->dot.r.p1 = op, f->dot.r.p2 = r.p2;
			p = r.p2+1;	/* exit next loop */
		}else{
			if(sel.p[0].p1==sel.p[0].p2){	/* empty match? */
				if(sel.p[0].p1==op){
					p++;
					continue;
				}
				p = sel.p[0].p2+1;
			}else
				p = sel.p[0].p2;
			if(xy)
				f->dot.r = sel.p[0];
			else
				f->dot.r.p1 = op, f->dot.r.p2 = sel.p[0].p1;
		}
		op = sel.p[0].p2;
		cmdexec(f, cp->ccmd);
		compile(cp->re);
	}
	--nest;
}

void
linelooper(File *f, Cmd *cp)
{
	Posn p;
	Range r, linesel;
	Address a, a3;

	nest++;
	r = addr.r;
	a3.f = f;
	a3.r.p1 = a3.r.p2 = r.p1;
	for(p = r.p1; p<r.p2; p = a3.r.p2){
		a3.r.p1 = a3.r.p2;
/*pjw		if(p!=r.p1 || (linesel = lineaddr((Posn)0, a3, 1)).r.p2==p)*/
		if(p!=r.p1 || (a = lineaddr((Posn)0, a3, 1), linesel = a.r, linesel.p2==p)){
			a = lineaddr((Posn)1, a3, 1);
			linesel = a.r;
		}
		if(linesel.p1 >= r.p2)
			break;
		if(linesel.p2 >= r.p2)
			linesel.p2 = r.p2;
		if(linesel.p2 > linesel.p1)
			if(linesel.p1>=a3.r.p2 && linesel.p2>a3.r.p2){
				f->dot.r = linesel;
				cmdexec(f, cp->ccmd);
				a3.r = linesel;
				continue;
			}
		break;
	}
	--nest;
}

void
filelooper(Cmd *cp, int XY)
{
	File *f, *cur;
	int i;

	if(Glooping++)
		error(EnestXY);
	nest++;
	settempfile();
	cur = curfile;
	for(i = 0; i<tempfile.nused; i++){
		f = tempfile.filepptr[i];
		if(f==cmd)
			continue;
		if(cp->re==0 || filematch(f, cp->re)==XY)
			cmdexec(f, cp->ccmd);
	}
	if(cur && whichmenu(cur)>=0)	/* check that cur is still a file */
		current(cur);
	--Glooping;
	--nest;
}