eval.c

早期freebsd实现

	case Node_mod:
		if (x2 == 0)
			fatal("division by zero attempted in mod");
#ifndef FMOD_MISSING
		return tmp_number(fmod (x1, x2));
#else
		(void) modf(x1 / x2, &x);
		return tmp_number(x1 - x * x2);
#endif

	case Node_plus:
		return tmp_number(x1 + x2);

	case Node_minus:
		return tmp_number(x1 - x2);

	case Node_var_array:
		fatal("attempt to use an array in a scalar context");

	default:
		fatal("illegal type (%d) in tree_eval", tree->type);
	}
	return 0;
}

/* Is TREE true or false?  Returns 0==false, non-zero==true */
static int
eval_condition(tree)
register NODE *tree;
{
	register NODE *t1;
	register int ret;

	if (tree == NULL)	/* Null trees are the easiest kinds */
		return 1;
	if (tree->type == Node_line_range) {
		/*
		 * Node_line_range is kind of like Node_match, EXCEPT: the
		 * lnode field (more properly, the condpair field) is a node
		 * of a Node_cond_pair; whether we evaluate the lnode of that
		 * node or the rnode depends on the triggered word.  More
		 * precisely:  if we are not yet triggered, we tree_eval the
		 * lnode; if that returns true, we set the triggered word. 
		 * If we are triggered (not ELSE IF, note), we tree_eval the
		 * rnode, clear triggered if it succeeds, and perform our
		 * action (regardless of success or failure).  We want to be
		 * able to begin and end on a single input record, so this
		 * isn't an ELSE IF, as noted above.
		 */
		if (!tree->triggered)
			if (!eval_condition(tree->condpair->lnode))
				return 0;
			else
				tree->triggered = 1;
		/* Else we are triggered */
		if (eval_condition(tree->condpair->rnode))
			tree->triggered = 0;
		return 1;
	}

	/*
	 * Could just be J.random expression. in which case, null and 0 are
	 * false, anything else is true 
	 */

	t1 = tree_eval(tree);
	if (t1->flags & MAYBE_NUM)
		(void) force_number(t1);
	if (t1->flags & NUMBER)
		ret = t1->numbr != 0.0;
	else
		ret = t1->stlen != 0;
	free_temp(t1);
	return ret;
}

/*
 * compare two nodes, returning negative, 0, positive
 */
int
cmp_nodes(t1, t2)
register NODE *t1, *t2;
{
	register int ret;
	register int len1, len2;

	if (t1 == t2)
		return 0;
	if (t1->flags & MAYBE_NUM)
		(void) force_number(t1);
	if (t2->flags & MAYBE_NUM)
		(void) force_number(t2);
	if ((t1->flags & NUMBER) && (t2->flags & NUMBER)) {
		if (t1->numbr == t2->numbr) return 0;
		else if (t1->numbr - t2->numbr < 0)  return -1;
		else return 1;
	}
	(void) force_string(t1);
	(void) force_string(t2);
	len1 = t1->stlen;
	len2 = t2->stlen;
	if (len1 == 0 || len2 == 0)
		return len1 - len2;
	ret = memcmp(t1->stptr, t2->stptr, len1 <= len2 ? len1 : len2);
	return ret == 0 ? len1-len2 : ret;
}

static NODE *
op_assign(tree)
register NODE *tree;
{
	AWKNUM rval, lval;
	NODE **lhs;
	AWKNUM t1, t2;
	long ltemp;
	NODE *tmp;
	Func_ptr after_assign = NULL;

	lhs = get_lhs(tree->lnode, &after_assign);
	lval = force_number(*lhs);

	/*
	 * Can't unref *lhs until we know the type; doing so
	 * too early breaks   x += x   sorts of things.
	 */
	switch(tree->type) {
	case Node_preincrement:
	case Node_predecrement:
		unref(*lhs);
		*lhs = make_number(lval +
			       (tree->type == Node_preincrement ? 1.0 : -1.0));
		if (after_assign)
			(*after_assign)();
		return *lhs;

	case Node_postincrement:
	case Node_postdecrement:
		unref(*lhs);
		*lhs = make_number(lval +
			       (tree->type == Node_postincrement ? 1.0 : -1.0));
		if (after_assign)
			(*after_assign)();
		return tmp_number(lval);
	default:
		break;	/* handled below */
	}

	tmp = tree_eval(tree->rnode);
	rval = force_number(tmp);
	free_temp(tmp);
	unref(*lhs);
	switch(tree->type) {
	case Node_assign_exp:
		if ((ltemp = rval) == rval) {	/* integer exponent */
			if (ltemp == 0)
				*lhs = make_number((AWKNUM) 1);
			else if (ltemp == 1)
				*lhs = make_number(lval);
			else {
				/* doing it this way should be more precise */
				for (t1 = t2 = lval; --ltemp; )
					t1 *= t2;
				*lhs = make_number(t1);
			}
		} else
			*lhs = make_number((AWKNUM) pow((double) lval, (double) rval));
		break;

	case Node_assign_times:
		*lhs = make_number(lval * rval);
		break;

	case Node_assign_quotient:
		if (rval == (AWKNUM) 0)
			fatal("division by zero attempted in /=");
#ifdef _CRAY
		/*
		 * special case for integer division, put in for Cray
		 */
		ltemp = rval;
		if (ltemp == 0) {
			*lhs = make_number(lval / rval);
			break;
		}
		ltemp = (long) lval / ltemp;
		if (ltemp * lval == rval)
			*lhs = make_number((AWKNUM) ltemp);
		else
#endif
			*lhs = make_number(lval / rval);
		break;

	case Node_assign_mod:
		if (rval == (AWKNUM) 0)
			fatal("division by zero attempted in %=");
#ifndef FMOD_MISSING
		*lhs = make_number(fmod(lval, rval));
#else
		(void) modf(lval / rval, &t1);
		t2 = lval - rval * t1;
		*lhs = make_number(t2);
#endif
		break;

	case Node_assign_plus:
		*lhs = make_number(lval + rval);
		break;

	case Node_assign_minus:
		*lhs = make_number(lval - rval);
		break;
	default:
		cant_happen();
	}
	if (after_assign)
		(*after_assign)();
	return *lhs;
}

NODE **stack_ptr;

static NODE *
func_call(name, arg_list)
NODE *name;		/* name is a Node_val giving function name */
NODE *arg_list;		/* Node_expression_list of calling args. */
{
	register NODE *arg, *argp, *r;
	NODE *n, *f;
	jmp_buf volatile func_tag_stack;
	jmp_buf volatile loop_tag_stack;
	int volatile save_loop_tag_valid = 0;
	NODE **volatile save_stack, *save_ret_node;
	NODE **volatile local_stack = NULL, **sp;
	int count;
	extern NODE *ret_node;

	/*
	 * retrieve function definition node
	 */
	f = lookup(name->stptr);
	if (!f || f->type != Node_func)
		fatal("function `%s' not defined", name->stptr);
#ifdef FUNC_TRACE
	fprintf(stderr, "function %s called\n", name->stptr);
#endif
	count = f->lnode->param_cnt;
	if (count)
		emalloc(local_stack, NODE **, count*sizeof(NODE *), "func_call");
	sp = local_stack;

	/*
	 * for each calling arg. add NODE * on stack
	 */
	for (argp = arg_list; count && argp != NULL; argp = argp->rnode) {
		arg = argp->lnode;
		getnode(r);
		r->type = Node_var;
		/*
		 * call by reference for arrays; see below also
		 */
		if (arg->type == Node_param_list)
			arg = stack_ptr[arg->param_cnt];
		if (arg->type == Node_var_array)
			*r = *arg;
		else {
			n = tree_eval(arg);
			r->lnode = dupnode(n);
			r->rnode = (NODE *) NULL;
			free_temp(n);
  		}
		*sp++ = r;
		count--;
	}
	if (argp != NULL)	/* left over calling args. */
		warning(
		    "function `%s' called with more arguments than declared",
		    name->stptr);
	/*
	 * add remaining params. on stack with null value
	 */
	while (count-- > 0) {
		getnode(r);
		r->type = Node_var;
		r->lnode = Nnull_string;
		r->rnode = (NODE *) NULL;
		*sp++ = r;
	}

	/*
	 * Execute function body, saving context, as a return statement
	 * will longjmp back here.
	 *
	 * Have to save and restore the loop_tag stuff so that a return
	 * inside a loop in a function body doesn't scrog any loops going
	 * on in the main program.  We save the necessary info in variables
	 * local to this function so that function nesting works OK.
	 * We also only bother to save the loop stuff if we're in a loop
	 * when the function is called.
	 */
	if (loop_tag_valid) {
		int junk = 0;

		save_loop_tag_valid = (volatile int) loop_tag_valid;
		PUSH_BINDING(loop_tag_stack, loop_tag, junk);
		loop_tag_valid = 0;
	}
	save_stack = stack_ptr;
	stack_ptr = local_stack;
	PUSH_BINDING(func_tag_stack, func_tag, func_tag_valid);
	save_ret_node = ret_node;
	ret_node = Nnull_string;	/* default return value */
	if (setjmp(func_tag) == 0)
		(void) interpret(f->rnode);

	r = ret_node;
	ret_node = (NODE *) save_ret_node;
	RESTORE_BINDING(func_tag_stack, func_tag, func_tag_valid);
	stack_ptr = (NODE **) save_stack;

	/*
	 * here, we pop each parameter and check whether
	 * it was an array.  If so, and if the arg. passed in was
	 * a simple variable, then the value should be copied back.
	 * This achieves "call-by-reference" for arrays.
	 */
	sp = local_stack;
	count = f->lnode->param_cnt;
	for (argp = arg_list; count > 0 && argp != NULL; argp = argp->rnode) {
		arg = argp->lnode;
		if (arg->type == Node_param_list)
			arg = stack_ptr[arg->param_cnt];
		n = *sp++;
		if (arg->type == Node_var && n->type == Node_var_array) {
			/* should we free arg->var_value ? */
			arg->var_array = n->var_array;
			arg->type = Node_var_array;
		}
		unref(n->lnode);
		freenode(n);
		count--;
	}
	while (count-- > 0) {
		n = *sp++;
		/* if n is an (local) array, all the elements should be freed */
		if (n->type == Node_var_array) {
			assoc_clear(n);
			free(n->var_array);
		}
		unref(n->lnode);
		freenode(n);
	}
	if (local_stack)
		free((char *) local_stack);

	/* Restore the loop_tag stuff if necessary. */
	if (save_loop_tag_valid) {
		int junk = 0;

		loop_tag_valid = (int) save_loop_tag_valid;
		RESTORE_BINDING(loop_tag_stack, loop_tag, junk);
	}

	if (!(r->flags & PERM))
		r->flags |= TEMP;
	return r;
}

/*
 * This returns a POINTER to a node pointer. get_lhs(ptr) is the current
 * value of the var, or where to store the var's new value 
 */

NODE **
get_lhs(ptr, assign)
register NODE *ptr;
Func_ptr *assign;
{
	register NODE **aptr = NULL;
	register NODE *n;

	switch (ptr->type) {
	case Node_var_array:
		fatal("attempt to use an array in a scalar context");
	case Node_var:
		aptr = &(ptr->var_value);
#ifdef DEBUG
		if (ptr->var_value->stref <= 0)
			cant_happen();
#endif
		break;

	case Node_FIELDWIDTHS:
		aptr = &(FIELDWIDTHS_node->var_value);
		if (assign)
			*assign = set_FIELDWIDTHS;
		break;

	case Node_RS:
		aptr = &(RS_node->var_value);
		if (assign)
			*assign = set_RS;
		break;

	case Node_FS:
		aptr = &(FS_node->var_value);
		if (assign)
			*assign = set_FS;
		break;

	case Node_FNR:
		unref(FNR_node->var_value);
		FNR_node->var_value = make_number((AWKNUM) FNR);
		aptr = &(FNR_node->var_value);
		if (assign)
			*assign = set_FNR;
		break;

	case Node_NR:
		unref(NR_node->var_value);
		NR_node->var_value = make_number((AWKNUM) NR);
		aptr = &(NR_node->var_value);
		if (assign)
			*assign = set_NR;
		break;

	case Node_NF:
		if (NF == -1)
			(void) get_field(HUGE-1, assign); /* parse record */
		unref(NF_node->var_value);
		NF_node->var_value = make_number((AWKNUM) NF);
		aptr = &(NF_node->var_value);
		if (assign)
			*assign = set_NF;
		break;

	case Node_IGNORECASE:
		unref(IGNORECASE_node->var_value);
		IGNORECASE_node->var_value = make_number((AWKNUM) IGNORECASE);
		aptr = &(IGNORECASE_node->var_value);
		if (assign)
			*assign = set_IGNORECASE;
		break;

	case Node_OFMT:
		aptr = &(OFMT_node->var_value);
		if (assign)
			*assign = set_OFMT;
		break;

	case Node_CONVFMT:
		aptr = &(CONVFMT_node->var_value);
		if (assign)
			*assign = set_CONVFMT;
		break;

	case Node_ORS:
		aptr = &(ORS_node->var_value);
		if (assign)
			*assign = set_ORS;
		break;

	case Node_OFS:
		aptr = &(OFS_node->var_value);
		if (assign)
			*assign = set_OFS;
		break;

	case Node_param_list:
		aptr = &(stack_ptr[ptr->param_cnt]->var_value);
		break;

	case Node_field_spec:
		{
		int field_num;

		n = tree_eval(ptr->lnode);
		field_num = (int) force_number(n);
		free_temp(n);
		if (field_num < 0)
			fatal("attempt to access field %d", field_num);
		if (field_num == 0 && field0_valid) {	/* short circuit */
			aptr = &fields_arr[0];
			if (assign)
				*assign = reset_record;
			break;
		}
		aptr = get_field(field_num, assign);
		break;
		}
	case Node_subscript:
		n = ptr->lnode;
		if (n->type == Node_param_list)
			n = stack_ptr[n->param_cnt];
		aptr = assoc_lookup(n, concat_exp(ptr->rnode));
		break;

	case Node_func:
		fatal ("`%s' is a function, assignment is not allowed",
			ptr->lnode->param);
	default:
		cant_happen();
	}
	return aptr;
}

static NODE *
match_op(tree)
register NODE *tree;
{
	register NODE *t1;
	register Regexp *rp;
	int i;
	int match = 1;

	if (tree->type == Node_nomatch)
		match = 0;
	if (tree->type == Node_regex)
		t1 = *get_field(0, (Func_ptr *) 0);
	else {
		t1 = force_string(tree_eval(tree->lnode));
		tree = tree->rnode;
	}
	rp = re_update(tree);
	i = research(rp, t1->stptr, 0, t1->stlen, 0);
	i = (i == -1) ^ (match == 1);
	free_temp(t1);
	return tmp_number((AWKNUM) i);
}

void
set_IGNORECASE()
{
	static int warned = 0;

	if ((do_lint || do_unix) && ! warned) {
		warned = 1;
		warning("IGNORECASE not supported in compatibility mode");
	}
	IGNORECASE = (force_number(IGNORECASE_node->var_value) != 0.0);
	set_FS();
}

void
set_OFS()
{
	OFS = force_string(OFS_node->var_value)->stptr;
	OFSlen = OFS_node->var_value->stlen;
	OFS[OFSlen] = '\0';
}

void
set_ORS()
{
	ORS = force_string(ORS_node->var_value)->stptr;
	ORSlen = ORS_node->var_value->stlen;
	ORS[ORSlen] = '\0';
}

static NODE **fmt_list = NULL;
static int fmt_ok P((NODE *n));
static int fmt_index P((NODE *n));

static int
fmt_ok(n)
NODE *n;
{
	/* to be done later */
	return 1;
}

static int
fmt_index(n)
NODE *n;
{
	register int ix = 0;
	static int fmt_num = 4;
	static int fmt_hiwater = 0;

	if (fmt_list == NULL)
		emalloc(fmt_list, NODE **, fmt_num*sizeof(*fmt_list), "fmt_index");
	(void) force_string(n);
	while (ix < fmt_hiwater) {
		if (cmp_nodes(fmt_list[ix], n) == 0)
			return ix;
		ix++;
	}
	/* not found */
	n->stptr[n->stlen] = '\0';
	if (!fmt_ok(n))
		warning("bad FMT specification");
	if (fmt_hiwater >= fmt_num) {
		fmt_num *= 2;
		emalloc(fmt_list, NODE **, fmt_num, "fmt_index");
	}
	fmt_list[fmt_hiwater] = dupnode(n);
	return fmt_hiwater++;
}

void
set_OFMT()
{
	OFMTidx = fmt_index(OFMT_node->var_value);
	OFMT = fmt_list[OFMTidx]->stptr;
}

void
set_CONVFMT()
{
	CONVFMTidx = fmt_index(CONVFMT_node->var_value);
	CONVFMT = fmt_list[CONVFMTidx]->stptr;
}