Iterable<MacroFunction> getMacroFunctions(String name);

    Collection<Macro> getAllMacros();
    Collection<MacroFunction> getAllMacroFunctions();

    boolean hasMacros();
    boolean hasMacroFunctions();

    /**
     * Returns a copy of these directives, with #import directives removed.
     */
    IncludeDirectives discardImports();

    IncludeDirectives EMPTY = new IncludeDirectives() {

    }

    /**
     * Appends a single file.
     */
    public void append(File file, IncludeDirectives includeDirectives) {
        if (!includeDirectives.hasMacros() && !includeDirectives.hasMacroFunctions()) {
            // Ignore
            return;
        }
        if (visible == null) {
            visible = new LinkedHashMap<File, IncludeDirectives>();
            visible.put(file, includeDirectives);

        return macroFunctions.values();
    }

    @Override
    public boolean hasMacros() {
        return !macros.isEmpty();
    }

    @Override
    public boolean hasMacroFunctions() {
        return !macroFunctions.isEmpty();
    }

    @Override
    public IncludeDirectives discardImports() {

        included.hasMacros() >> { !macros.empty }
        included.getAllMacroFunctions() >> macroFunctions
        included.getMacroFunctions(_) >> { String name -> macroFunctions.findAll {it.name == name} }
        included.hasMacroFunctions() >> { !macroFunctions.empty }
    }

    protected TestFile getSourceFile() {
        sourceDirectory.file('source.c')
    }

    def resolve(Include include) {