1/*
2 * Copyright © 2007,2008,2009,2010 Red Hat, Inc.
3 * Copyright © 2012,2018 Google, Inc.
4 *
5 * This is part of HarfBuzz, a text shaping library.
6 *
7 * Permission is hereby granted, without written agreement and without
8 * license or royalty fees, to use, copy, modify, and distribute this
9 * software and its documentation for any purpose, provided that the
10 * above copyright notice and the following two paragraphs appear in
11 * all copies of this software.
12 *
13 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
14 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
15 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
16 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
17 * DAMAGE.
18 *
19 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
20 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
21 * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
22 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
23 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
24 *
25 * Red Hat Author(s): Behdad Esfahbod
26 * Google Author(s): Behdad Esfahbod
27 */
28
29#ifndef HB_DISPATCH_HH
30#define HB_DISPATCH_HH
31
32#include "hb.hh"
33
34/*
35 * Dispatch
36 */
37
38template <typename Context, typename Return=hb_empty_t, unsigned int MaxDebugDepth=0>
39struct hb_dispatch_context_t
40{
41 private:
42 /* https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern */
43 const Context* thiz () const { return static_cast<const Context *> (this); }
44 Context* thiz () { return static_cast< Context *> (this); }
45 public:
46 const char *get_name () { return "UNKNOWN"; }
47 static constexpr unsigned max_debug_depth = MaxDebugDepth;
48 typedef Return return_t;
49 template <typename T, typename F>
50 bool may_dispatch (const T *obj HB_UNUSED, const F *format HB_UNUSED) { return true; }
51 template <typename T, typename ...Ts>
52 return_t dispatch (const T &obj, Ts&&... ds)
53 { return obj.dispatch (thiz (), std::forward<Ts> (ds)...); }
54 static return_t no_dispatch_return_value () { return Context::default_return_value (); }
55 static bool stop_sublookup_iteration (const return_t r HB_UNUSED) { return false; }
56 unsigned debug_depth = 0;
57};
58
59
60#endif /* HB_DISPATCH_HH */
61