hb-dispatch.hh (2301B)
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 38 template <typename Context, typename Return=hb_empty_t, unsigned int MaxDebugDepth=0> 39 struct 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 */