[cplusplus] Add hb-cplusplus.hh
Fixes https://github.com/harfbuzz/harfbuzz/issues/2152
diff --git a/src/hb-cplusplus.hh b/src/hb-cplusplus.hh
new file mode 100644
index 0000000..122c692
--- /dev/null
+++ b/src/hb-cplusplus.hh
@@ -0,0 +1,133 @@
+/*
+ * Copyright © 2022 Behdad Esfahbod
+ *
+ * This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ */
+
+#ifndef HB_CPLUSPLUS_HH
+#define HB_CPLUSPLUS_HH
+
+#include "hb.h"
+
+HB_BEGIN_DECLS
+HB_END_DECLS
+
+#ifdef __cplusplus
+
+#include <utility>
+
+#if 0
+#if !(__cplusplus >= 201103L)
+#error "HarfBuzz C++ helpers require C++11"
+#endif
+#endif
+
+namespace hb {
+
+
+template <typename T>
+struct vtable;
+
+template <typename T>
+struct shared_ptr
+{
+ using v = vtable<T>;
+
+ explicit shared_ptr (T *p = nullptr) : p (p) {}
+ shared_ptr (const shared_ptr &o) : p (v::reference (o.p)) {}
+ shared_ptr (shared_ptr &&o) : p (o.p) { o.p = nullptr; }
+ shared_ptr& operator = (const shared_ptr &o) { if (p != o.p) { destroy (); p = o.p; reference (); } return *this; }
+ shared_ptr& operator = (shared_ptr &&o) { destroy (); p = o.p; o.p = nullptr; return *this; }
+ ~shared_ptr () { v::destroy (p); }
+
+ T* get() const { return p; }
+
+ void swap (shared_ptr &o) { std::swap (p, o.p); }
+ friend void swap (shared_ptr &a, shared_ptr &b) { std::swap (a.p, b.p); }
+
+ operator T * () const { return p; }
+ T& operator * () const { return *get (); }
+ T* operator -> () const { return get (); }
+ operator bool () { return p; }
+ bool operator == (const shared_ptr &o) { return p == o.p; }
+ bool operator != (const shared_ptr &o) { return p != o.p; }
+
+ static T* get_empty() { return v::get_empty (); }
+ void reference() { v::reference (p); }
+ void destroy() { v::destroy (p); }
+ void set_user_data (hb_user_data_key_t *key,
+ void *value,
+ hb_destroy_func_t destroy,
+ hb_bool_t replace) { v::set_user_data (p, key, value, destroy, replace); }
+ void * get_user_data (hb_user_data_key_t *key) { return v::get_user_data (p, key); }
+
+ private:
+ T *p;
+};
+
+template <typename T,
+ T * (*_get_empty) (void),
+ T * (*_reference) (T *),
+ void (*_destroy) (T *),
+ hb_bool_t (*_set_user_data) (T *,
+ hb_user_data_key_t *,
+ void *,
+ hb_destroy_func_t,
+ hb_bool_t),
+ void * (*_get_user_data) (T *,
+ hb_user_data_key_t *)>
+struct vtable_t
+{
+ static constexpr auto get_empty = _get_empty;
+ static constexpr auto reference = _reference;
+ static constexpr auto destroy = _destroy;
+ static constexpr auto set_user_data = _set_user_data;
+ static constexpr auto get_user_data = _get_user_data;
+};
+
+#define HB_DEFINE_VTABLE(name) \
+ template<> \
+ struct vtable<hb_##name##_t> \
+ : vtable_t<hb_##name##_t, \
+ &hb_##name##_get_empty, \
+ &hb_##name##_reference, \
+ &hb_##name##_destroy, \
+ &hb_##name##_set_user_data, \
+ &hb_##name##_get_user_data> {}
+
+HB_DEFINE_VTABLE (buffer);
+HB_DEFINE_VTABLE (blob);
+HB_DEFINE_VTABLE (face);
+HB_DEFINE_VTABLE (font);
+HB_DEFINE_VTABLE (font_funcs);
+HB_DEFINE_VTABLE (map);
+HB_DEFINE_VTABLE (set);
+HB_DEFINE_VTABLE (shape_plan);
+HB_DEFINE_VTABLE (unicode_funcs);
+
+#undef HB_DEFINE_VTABLE
+
+
+} // namespace hb
+
+#endif /* __cplusplus */
+
+#endif /* HB_CPLUSPLUS_HH */
