UnifiedCall(Expression nameExp,
    Map namedArgs,
    TemplateElement nestedBlock,
    List bodyParameterNames) 
{
        this.nameExp = nameExp;
        this.namedArgs = namedArgs;
        this.nestedBlock = nestedBlock;
        this.bodyParameterNames = bodyParameterNames;
}

 UnifiedCall(Expression nameExp,
    List positionalArgs,
    TemplateElement nestedBlock,
    List bodyParameterNames) 
{
        this.nameExp = nameExp;
        this.positionalArgs = positionalArgs;
        if (nestedBlock == TextBlock.EMPTY_BLOCK) {
            nestedBlock = null;
        }
        this.nestedBlock = nestedBlock;
        this.bodyParameterNames = bodyParameterNames;
}

  void accept(Environment env) throws IOException, TemplateException 
{
        TemplateModel tm = nameExp.getAsTemplateModel(env);
        if (tm == Macro.DO_NOTHING_MACRO) return; // shortcut here.
        if (tm instanceof Macro) {
            Macro macro = (Macro) tm;
            if (macro.isFunction && !legacySyntax) {
                throw new TemplateException("Routine " + macro.getName() + 
                        " is a function. A function can only be called " +
                        "within the evaluation of an expression.", env);
            }    
            env.visit(macro, namedArgs, positionalArgs, bodyParameterNames,
                    nestedBlock);
        }
        else {
            boolean isDirectiveModel = tm instanceof TemplateDirectiveModel; 
            if (isDirectiveModel || tm instanceof TemplateTransformModel) {
                Map args;
                if (namedArgs != null && !namedArgs.isEmpty()) {
                    args = new HashMap();
                    for (Iterator it = namedArgs.entrySet().iterator(); it.hasNext();) {
                        Map.Entry entry = (Map.Entry) it.next();
                        String key = (String) entry.getKey();
                        Expression valueExp = (Expression) entry.getValue();
                        TemplateModel value = valueExp.getAsTemplateModel(env);
                        args.put(key, value);
                    }
                } else {
                    args = EmptyMap.instance;
                }
                if(isDirectiveModel) {
                    env.visit(nestedBlock, (TemplateDirectiveModel) tm, args, 
                            bodyParameterNames);
                }
                else { 
                    env.visit(nestedBlock, (TemplateTransformModel) tm, args);
                }
            }
            else if (tm == null) {
                throw new InvalidReferenceException(this.getStartLocation() + " " +
                        nameExp + " not found.", env);
            } else {
                throw new TemplateException(getStartLocation() + ": " + nameExp + 
                        " is not a user-defined directive. It is a " + 
                        tm.getClass().getName(), env);
            }
        }
}

 public String getCanonicalForm() 
{
        StringBuffer buf = new StringBuffer("< @");
        buf.append(nameExp.getCanonicalForm());
        if (positionalArgs != null) {
            for (int i=0; i< positionalArgs.size(); i++) {
                Expression arg = (Expression) positionalArgs.get(i);
                if (i!=0) {
                    buf.append(',");
                }
                buf.append(' ");
                buf.append(arg.getCanonicalForm());
            }
        }
        else {
            ArrayList keys = new ArrayList(namedArgs.keySet());
            Collections.sort(keys);
            for (int i=0; i< keys.size();i++) {
                Expression arg = (Expression) namedArgs.get(keys.get(i));
                buf.append(' ");
                buf.append(keys.get(i));
                buf.append('=");
                buf.append(arg.getCanonicalForm());
            }
        }
        if (nestedBlock == null) {
            buf.append("/ >");
        } 
        else {
            buf.append(' >");
            buf.append(nestedBlock.getCanonicalForm());
            buf.append("< /@");
            if (nameExp instanceof Identifier || (nameExp instanceof Dot && ((Dot) nameExp).onlyHasIdentifiers())) {
                buf.append(nameExp);
            }
            buf.append(' >");
        }
        return buf.toString();
}

 public String getDescription() 
{
        return "user-directive " + nameExp;
}