sandbox/linux/bpf_dsl/cons.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef SANDBOX_LINUX_BPF_DSL_CONS_H_
   6 #define SANDBOX_LINUX_BPF_DSL_CONS_H_
   7
   8 #include "base/memory/ref_counted.h"
   9 #include "sandbox/sandbox_export.h"
  10
  11 namespace sandbox {
  12
  13 // Cons provides an immutable linked list abstraction as commonly
  14 // provided in functional programming languages like Lisp or Haskell.
  15 template <typename T>
  16 class Cons : public base::RefCounted<Cons<T> > {
  17  public:
  18   // List provides an abstraction for referencing a list of zero or
  19   // more Cons nodes.
  20   typedef scoped_refptr<const Cons<T> > List;
  21
  22   // Return this node's head element.
  23   const T& head() const { return head_; }
  24
  25   // Return this node's tail element.
  26   List tail() const { return tail_; }
  27
  28   // Construct a new List using |head| and |tail|.
  29   static List Make(const T& head, List tail) {
  30     return make_scoped_refptr(new const Cons<T>(head, tail));
  31   }
  32
  33  private:
  34   Cons(const T& head, List tail) : head_(head), tail_(tail) {}
  35   virtual ~Cons() {}
  36
  37   T head_;
  38   List tail_;
  39
  40   friend class base::RefCounted<Cons<T> >;
  41   DISALLOW_COPY_AND_ASSIGN(Cons);
  42 };
  43
  44 }  // namespace sandbox
  45
  46 #endif  // SANDBOX_LINUX_BPF_DSL_CONS_H_