/*
 *  call-seq:
 *     untrace_var(symbol [, cmd] )   => array or nil
 *  
 *  Removes tracing for the specified command on the given global
 *  variable and returns +nil+. If no command is specified,
 *  removes all tracing for that variable and returns an array
 *  containing the commands actually removed.
 */

VALUE
rb_f_untrace_var(argc, argv)
    int argc;
    VALUE *argv;
{
    VALUE var, cmd;
    ID id;
    struct global_entry *entry;
    struct trace_var *trace;

    rb_secure(4);
    rb_scan_args(argc, argv, "11", &var, &cmd);
    id = rb_to_id(var);
    if (!st_lookup(rb_global_tbl, id, (st_data_t *)&entry)) {
	rb_name_error(id, "undefined global variable %s", rb_id2name(id));
    }

    trace = entry->var->trace;
    if (NIL_P(cmd)) {
	VALUE ary = rb_ary_new();

	while (trace) {
	    struct trace_var *next = trace->next;
	    rb_ary_push(ary, (VALUE)trace->data);
	    trace->removed = 1;
	    trace = next;
	}

	if (!entry->var->block_trace) remove_trace(entry->var);
	return ary;
    }
    else {
	while (trace) {
	    if (trace->data == cmd) {
		trace->removed = 1;
		if (!entry->var->block_trace) remove_trace(entry->var);
		return rb_ary_new3(1, cmd);
	    }
	    trace = trace->next;
	}
    }
    return Qnil;
}