run.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

{
	int i;
	Cell *x, *y;
	Awkfloat j;

	x = execute(a[0]);
	y = execute(a[1]);
	if (x->tval&NUM && y->tval&NUM) {
		j = x->fval - y->fval;
		i = j<0? -1: (j>0? 1: 0);
	} else {
		i = strcmp(getsval(x), getsval(y));
	}
	tempfree(x);
	tempfree(y);
	switch (n) {
	case LT:	if (i<0) return(True);
			else return(False);
	case LE:	if (i<=0) return(True);
			else return(False);
	case NE:	if (i!=0) return(True);
			else return(False);
	case EQ:	if (i == 0) return(True);
			else return(False);
	case GE:	if (i>=0) return(True);
			else return(False);
	case GT:	if (i>0) return(True);
			else return(False);
	default:	/* can't happen */
		FATAL("unknown relational operator %d", n);
	}
	return 0;	/*NOTREACHED*/
}

void tfree(Cell *a)	/* free a tempcell */
{
	if (freeable(a)) {
		   dprintf( ("freeing %s %s %o\n", a->nval, a->sval, a->tval) );
		xfree(a->sval);
	}
	if (a == tmps)
		FATAL("tempcell list is curdled");
	a->cnext = tmps;
	tmps = a;
}

Cell *gettemp(void)	/* get a tempcell */
{	int i;
	Cell *x;

	if (!tmps) {
		tmps = (Cell *) calloc(100, sizeof(Cell));
		if (!tmps)
			FATAL("out of space for temporaries");
		for(i = 1; i < 100; i++)
			tmps[i-1].cnext = &tmps[i];
		tmps[i-1].cnext = 0;
	}
	x = tmps;
	tmps = x->cnext;
	*x = tempcell;
	return(x);
}

Cell *indirect(Node **a, int n)	/* $( a[0] ) */
{
	Cell *x;
	int m;
	char *s;

	x = execute(a[0]);
	m = (int) getfval(x);
	if (m == 0 && !is_number(s = getsval(x)))	/* suspicion! */
		FATAL("illegal field $(%s), name \"%s\"", s, x->nval);
		/* BUG: can x->nval ever be null??? */
	tempfree(x);
	x = fieldadr(m);
	x->ctype = OCELL;	/* BUG?  why are these needed? */
	x->csub = CFLD;
	return(x);
}

Cell *substr(Node **a, int nnn)		/* substr(a[0], a[1], a[2]) */
{
	int k, m, n;
	char *s, *p;
	int temp;
	Cell *x, *y, *z = 0;

	x = execute(a[0]);
	y = execute(a[1]);
	if (a[2] != 0)
		z = execute(a[2]);
	s = getsval(x);
	k = countposn(s, strlen(s)) + 1;
	if (k <= 1) {
		tempfree(x);
		tempfree(y);
		if (a[2] != 0)
			tempfree(z);
		x = gettemp();
		setsval(x, "");
		return(x);
	}
	m = (int) getfval(y);
	if (m <= 0)
		m = 1;
	else if (m > k)
		m = k;
	tempfree(y);
	if (a[2] != 0) {
		n = (int) getfval(z);
		tempfree(z);
	} else
		n = k - 1;
	if (n < 0)
		n = 0;
	else if (n > k - m)
		n = k - m;
	   dprintf( ("substr: m=%d, n=%d, s=%s\n", m, n, s) );
	y = gettemp();
	while (*s && --m)
		 s += mblen(s, k);
	for (p = s; *p && n--; p += mblen(p, k))
			;
	temp = *p;	/* with thanks to John Linderman */
	*p = '\0';
	setsval(y, s);
	*p = temp;
	tempfree(x);
	return(y);
}

Cell *sindex(Node **a, int nnn)		/* index(a[0], a[1]) */
{
	Cell *x, *y, *z;
	char *s1, *s2, *p1, *p2, *q;
	Awkfloat v = 0.0;

	x = execute(a[0]);
	s1 = getsval(x);
	y = execute(a[1]);
	s2 = getsval(y);

	z = gettemp();
	for (p1 = s1; *p1 != '\0'; p1++) {
		for (q=p1, p2=s2; *p2 != '\0' && *q == *p2; q++, p2++)
			;
		if (*p2 == '\0') {
			v = (Awkfloat) countposn(s1, p1-s1) + 1;	/* origin 1 */
			break;
		}
	}
	tempfree(x);
	tempfree(y);
	setfval(z, v);
	return(z);
}

#define	MAXNUMSIZE	50

int format(char **pbuf, int *pbufsize, char *s, Node *a)	/* printf-like conversions */
{
	char *fmt;
	char *p, *t, *os;
	Cell *x;
	int flag = 0, n;
	int fmtwd; /* format width */
	int fmtsz = recsize;
	char *buf = *pbuf;
	int bufsize = *pbufsize;

	os = s;
	p = buf;
	if ((fmt = (char *) malloc(fmtsz)) == NULL)
		FATAL("out of memory in format()");
	while (*s) {
		adjbuf(&buf, &bufsize, MAXNUMSIZE+1+p-buf, recsize, &p, "format");
		if (*s != '%') {
			*p++ = *s++;
			continue;
		}
		if (*(s+1) == '%') {
			*p++ = '%';
			s += 2;
			continue;
		}
		/* have to be real careful in case this is a huge number, eg, %100000d */
		fmtwd = atoi(s+1);
		if (fmtwd < 0)
			fmtwd = -fmtwd;
		adjbuf(&buf, &bufsize, fmtwd+1+p-buf, recsize, &p, "format");
		for (t = fmt; (*t++ = *s) != '\0'; s++) {
			if (!adjbuf(&fmt, &fmtsz, MAXNUMSIZE+1+t-fmt, recsize, &t, 0))
				FATAL("format item %.30s... ran format() out of memory", os);
			if (isalpha(*s) && *s != 'l' && *s != 'h' && *s != 'L')
				break;	/* the ansi panoply */
			if (*s == '*') {
				x = execute(a);
				a = a->nnext;
				sprintf(t-1, "%d", fmtwd=(int) getfval(x));
				if (fmtwd < 0)
					fmtwd = -fmtwd;
				adjbuf(&buf, &bufsize, fmtwd+1+p-buf, recsize, &p, "format");
				t = fmt + strlen(fmt);
				tempfree(x);
			}
		}
		*t = '\0';
		if (fmtwd < 0)
			fmtwd = -fmtwd;
		adjbuf(&buf, &bufsize, fmtwd+1+p-buf, recsize, &p, "format");

		switch (*s) {
		case 'f': case 'e': case 'g': case 'E': case 'G':
			flag = 1;
			break;
		case 'd': case 'i':
			flag = 2;
			if(*(s-1) == 'l') break;
			*(t-1) = 'l';
			*t = 'd';
			*++t = '\0';
			break;
		case 'o': case 'x': case 'X': case 'u':
			flag = *(s-1) == 'l' ? 2 : 3;
			break;
		case 's':
			flag = 4;
			break;
		case 'c':
			flag = 5;
			break;
		default:
			WARNING("weird printf conversion %s", fmt);
			flag = 0;
			break;
		}
		if (a == NULL)
			FATAL("not enough args in printf(%s)", os);
		x = execute(a);
		a = a->nnext;
		n = MAXNUMSIZE;
		if (fmtwd > n)
			n = fmtwd;
		adjbuf(&buf, &bufsize, 1+n+p-buf, recsize, &p, "format");
		switch (flag) {
		case 0:	sprintf(p, "%s", fmt);	/* unknown, so dump it too */
			t = getsval(x);
			n = strlen(t);
			if (fmtwd > n)
				n = fmtwd;
			adjbuf(&buf, &bufsize, 1+strlen(p)+n+p-buf, recsize, &p, "format");
			p += strlen(p);
			sprintf(p, "%s", t);
			break;
		case 1:	sprintf(p, fmt, getfval(x)); break;
		case 2:	sprintf(p, fmt, (long) getfval(x)); break;
		case 3:	sprintf(p, fmt, (int) getfval(x)); break;
		case 4:
			t = getsval(x);
			n = strlen(t);
			if (fmtwd > n)
				n = fmtwd;
			if (!adjbuf(&buf, &bufsize, 1+n+p-buf, recsize, &p, 0))
				FATAL("huge string/format (%d chars) in printf %.30s... ran format() out of memory", n, t);
			sprintf(p, fmt, t);
			break;
		case 5:
			if (isnum(x)) {
				if (getfval(x))
					sprintf(p, fmt, (int) getfval(x));
				else{
					*p++ = '\0';
					*p = '\0';
				}
			} else
				sprintf(p, fmt, getsval(x)[0]);
			break;
		}
		tempfree(x);
		p += strlen(p);
		s++;
	}
	*p = '\0';
	free(fmt);
	for ( ; a; a = a->nnext)		/* evaluate any remaining args */
		execute(a);
	*pbuf = buf;
	*pbufsize = bufsize;
	return p - buf;
}

Cell *awksprintf(Node **a, int n)		/* sprintf(a[0]) */
{
	Cell *x;
	Node *y;
	char *buf;
	int bufsz=3*recsize;

	if ((buf = (char *) malloc(bufsz)) == NULL)
		FATAL("out of memory in awksprintf");
	y = a[0]->nnext;
	x = execute(a[0]);
	if (format(&buf, &bufsz, getsval(x), y) == -1)
		FATAL("sprintf string %.30s... too long.  can't happen.", buf);
	tempfree(x);
	x = gettemp();
	x->sval = buf;
	x->tval = STR;
	return(x);
}

Cell *awkprintf(Node **a, int n)		/* printf */
{	/* a[0] is list of args, starting with format string */
	/* a[1] is redirection operator, a[2] is redirection file */
	FILE *fp;
	Cell *x;
	Node *y;
	char *buf;
	int len;
	int bufsz=3*recsize;

	if ((buf = (char *) malloc(bufsz)) == NULL)
		FATAL("out of memory in awkprintf");
	y = a[0]->nnext;
	x = execute(a[0]);
	if ((len = format(&buf, &bufsz, getsval(x), y)) == -1)
		FATAL("printf string %.30s... too long.  can't happen.", buf);
	tempfree(x);
	if (a[1] == NULL) {
		/* fputs(buf, stdout); */
		fwrite(buf, len, 1, stdout);
		if (ferror(stdout))
			FATAL("write error on stdout");
	} else {
		fp = redirect(ptoi(a[1]), a[2]);
		/* fputs(buf, fp); */
		fwrite(buf, len, 1, fp);
		fflush(fp);
		if (ferror(fp))
			FATAL("write error on %s", filename(fp));
	}
	free(buf);
	return(True);
}

Cell *arith(Node **a, int n)	/* a[0] + a[1], etc.  also -a[0] */
{
	Awkfloat i, j = 0;
	double v;
	Cell *x, *y, *z;

	x = execute(a[0]);
	i = getfval(x);
	tempfree(x);
	if (n != UMINUS) {
		y = execute(a[1]);
		j = getfval(y);
		tempfree(y);
	}
	z = gettemp();
	switch (n) {
	case ADD:
		i += j;
		break;
	case MINUS:
		i -= j;
		break;
	case MULT:
		i *= j;
		break;
	case DIVIDE:
		if (j == 0)
			FATAL("division by zero");
		i /= j;
		break;
	case MOD:
		if (j == 0)
			FATAL("division by zero in mod");
		modf(i/j, &v);
		i = i - j * v;
		break;
	case UMINUS:
		i = -i;
		break;
	case POWER:
		if (j >= 0 && modf(j, &v) == 0.0)	/* pos integer exponent */
			i = ipow(i, (int) j);
		else
			i = errcheck(pow(i, j), "pow");
		break;
	default:	/* can't happen */
		FATAL("illegal arithmetic operator %d", n);
	}
	setfval(z, i);
	return(z);
}

double ipow(double x, int n)	/* x**n.  ought to be done by pow, but isn't always */
{
	double v;

	if (n <= 0)
		return 1;
	v = ipow(x, n/2);
	if (n % 2 == 0)
		return v * v;
	else
		return x * v * v;
}

Cell *incrdecr(Node **a, int n)		/* a[0]++, etc. */
{
	Cell *x, *z;
	int k;
	Awkfloat xf;

	x = execute(a[0]);
	xf = getfval(x);
	k = (n == PREINCR || n == POSTINCR) ? 1 : -1;
	if (n == PREINCR || n == PREDECR) {
		setfval(x, xf + k);
		return(x);
	}
	z = gettemp();
	setfval(z, xf);
	setfval(x, xf + k);
	tempfree(x);
	return(z);
}

Cell *assign(Node **a, int n)	/* a[0] = a[1], a[0] += a[1], etc. */
{		/* this is subtle; don't muck with it. */
	Cell *x, *y;
	Awkfloat xf, yf;
	double v;

	y = execute(a[1]);
	x = execute(a[0]);
	if (n == ASSIGN) {	/* ordinary assignment */
		if (x == y && !(x->tval & (FLD|REC)))	/* self-assignment: */
			;		/* leave alone unless it's a field */
		else if ((y->tval & (STR|NUM)) == (STR|NUM)) {
			setsval(x, getsval(y));
			x->fval = getfval(y);
			x->tval |= NUM;
		}
		else if (isstr(y))
			setsval(x, getsval(y));
		else if (isnum(y))
			setfval(x, getfval(y));
		else
			funnyvar(y, "read value of");
		tempfree(y);
		return(x);
	}
	xf = getfval(x);
	yf = getfval(y);
	switch (n) {
	case ADDEQ:
		xf += yf;
		break;
	case SUBEQ:
		xf -= yf;
		break;
	case MULTEQ:
		xf *= yf;
		break;
	case DIVEQ:
		if (yf == 0)
			FATAL("division by zero in /=");
		xf /= yf;
		break;
	case MODEQ:
		if (yf == 0)
			FATAL("division by zero in %%=");
		modf(xf/yf, &v);
		xf = xf - yf * v;
		break;
	case POWEQ:
		if (yf >= 0 && modf(yf, &v) == 0.0)	/* pos integer exponent */
			xf = ipow(xf, (int) yf);
		else
			xf = errcheck(pow(xf, yf), "pow");
		break;
	default:
		FATAL("illegal assignment operator %d", n);
		break;
	}
	tempfree(y);
	setfval(x, xf);
	return(x);
}

Cell *cat(Node **a, int q)	/* a[0] cat a[1] */
{
	Cell *x, *y, *z;
	int n1, n2;
	char *s;

	x = execute(a[0]);
	y = execute(a[1]);
	getsval(x);
	getsval(y);
	n1 = strlen(x->sval);
	n2 = strlen(y->sval);
	s = (char *) malloc(n1 + n2 + 1);
	if (s == NULL)
		FATAL("out of space concatenating %.15s... and %.15s...",
			x->sval, y->sval);
	strcpy(s, x->sval);
	strcpy(s+n1, y->sval);
	tempfree(y);
	z = gettemp();
	z->sval = s;
	z->tval = STR;
	tempfree(x);
	return(z);
}

Cell *pastat(Node **a, int n)	/* a[0] { a[1] } */
{
	Cell *x;

	if (a[0] == 0)
		x = execute(a[1]);
	else {
		x = execute(a[0]);
		if (istrue(x)) {
			tempfree(x);
			x = execute(a[1]);
		}
	}
	return x;
}

Cell *dopa2(Node **a, int n)	/* a[0], a[1] { a[2] } */
{
	Cell *x;
	int pair;

	pair = ptoi(a[3]);
	if (pairstack[pair] == 0) {
		x = execute(a[0]);
		if (istrue(x))
			pairstack[pair] = 1;
		tempfree(x);
	}
	if (pairstack[pair] == 1) {
		x = execute(a[1]);
		if (istrue(x))
			pairstack[pair] = 0;
		tempfree(x);
		x = execute(a[2]);
		return(x);
	}
	return(False);
}

Cell *split(Node **a, int nnn)	/* split(a[0], a[1], a[2]); a[3] is type */
{
	Cell *x = 0, *y, *ap;
	char *s;
	int sep;
	char *t, temp, num[50], *fs = 0;
	int n, tempstat, arg3type;

	y = execute(a[0]);	/* source string */
	s = getsval(y);
	arg3type = ptoi(a[3]);
	if (a[2] == 0)		/* fs string */
		fs = *FS;
	else if (arg3type == STRING) {	/* split(str,arr,"string") */
		x = execute(a[2]);
		fs = getsval(x);
	} else if (arg3type == REGEXPR)
		fs = "(regexpr)";	/* split(str,arr,/regexpr/) */
	else
		FATAL("illegal type of split");
	sep = *fs;
	ap = execute(a[1]);	/* array name */
	freesymtab(ap);
	   dprintf( ("split: s=|%s|, a=%s, sep=|%s|\n", s, ap->nval, fs) );
	ap->tval &= ~STR;
	ap->tval |= ARR;
	ap->sval = (char *) makesymtab(NSYMTAB);

	n = 0;
	if ((*s != '\0' && strlen(fs) > 1) || arg3type == REGEXPR) {	/* reg expr */
		void *p;
		if (arg3type == REGEXPR) {	/* it's ready already */
			p = (void *) a[2];
		} else {
			p = compre(fs);
		}
		t = s;
		if (nematch(p,s,t)) {
			do {
				n++;
				sprintf(num, "%d", n);
				temp = *patbeg;
				*patbeg = '\0';
				if (is_number(t))
					setsymtab(num, t, atof(t), STR|NUM, (Array *) ap->sval);
				else
					setsymtab(num, t, 0.0, STR, (Array *) ap->sval);
				*patbeg = temp;
				t = patbeg + patlen;
				if (t[-1] == 0 || *t == 0) {
					n++;
					sprintf(num, "%d", n);
					setsymtab(num, "", 0.0, STR, (Array *) ap->sval);
					goto spdone;
				}
			} while (nematch(p,s,t));
		}
		n++;
		sprintf(num, "%d", n);
		if (is_number(t))
			setsymtab(num, t, atof(t), STR|NUM, (Array *) ap->sval);
		else
			setsymtab(num, t, 0.0, STR, (Array *) ap->sval);
  spdone:
		p = NULL;
	} else if (sep == ' ') {
		for (n = 0; ; ) {
			while (*s == ' ' || *s == '\t' || *s == '\n')
				s++;
			if (*s == 0)
				break;
			n++;
			t = s;