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+/*
+ * Copyright © 2007,2008,2009,2010 Red Hat, Inc.
+ * Copyright © 2012,2018 Google, Inc.
+ *
+ * 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.
+ *
+ * Red Hat Author(s): Behdad Esfahbod
+ * Google Author(s): Behdad Esfahbod
+ */
+
+#ifndef HB_MACHINERY_HH
+#define HB_MACHINERY_HH
+
+#include "hb.hh"
+#include "hb-blob.hh"
+
+#include "hb-dispatch.hh"
+#include "hb-sanitize.hh"
+
+
+/*
+ * Casts
+ */
+
+/* StructAtOffset<T>(P,Ofs) returns the struct T& that is placed at memory
+ * location pointed to by P plus Ofs bytes. */
+template<typename Type>
+static inline const Type& StructAtOffset(const void *P, unsigned int offset)
+{ return * reinterpret_cast<const Type*> ((const char *) P + offset); }
+template<typename Type>
+static inline Type& StructAtOffset(void *P, unsigned int offset)
+{ return * reinterpret_cast<Type*> ((char *) P + offset); }
+template<typename Type>
+static inline const Type& StructAtOffsetUnaligned(const void *P, unsigned int offset)
+{
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wcast-align"
+ return * reinterpret_cast<const Type*> ((const char *) P + offset);
+#pragma GCC diagnostic pop
+}
+template<typename Type>
+static inline Type& StructAtOffsetUnaligned(void *P, unsigned int offset)
+{
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wcast-align"
+ return * reinterpret_cast<Type*> ((char *) P + offset);
+#pragma GCC diagnostic pop
+}
+
+/* StructAfter<T>(X) returns the struct T& that is placed after X.
+ * Works with X of variable size also. X must implement get_size() */
+template<typename Type, typename TObject>
+static inline const Type& StructAfter(const TObject &X)
+{ return StructAtOffset<Type>(&X, X.get_size()); }
+template<typename Type, typename TObject>
+static inline Type& StructAfter(TObject &X)
+{ return StructAtOffset<Type>(&X, X.get_size()); }
+
+
+/*
+ * Size checking
+ */
+
+/* Size signifying variable-sized array */
+#ifndef HB_VAR_ARRAY
+#define HB_VAR_ARRAY 1
+#endif
+
+/* Check _assertion in a method environment */
+#define _DEFINE_INSTANCE_ASSERTION1(_line, _assertion) \
+ void _instance_assertion_on_line_##_line () const \
+ { static_assert ((_assertion), ""); }
+# define _DEFINE_INSTANCE_ASSERTION0(_line, _assertion) _DEFINE_INSTANCE_ASSERTION1 (_line, _assertion)
+# define DEFINE_INSTANCE_ASSERTION(_assertion) _DEFINE_INSTANCE_ASSERTION0 (__LINE__, _assertion)
+
+/* Check that _code compiles in a method environment */
+#define _DEFINE_COMPILES_ASSERTION1(_line, _code) \
+ void _compiles_assertion_on_line_##_line () const \
+ { _code; }
+# define _DEFINE_COMPILES_ASSERTION0(_line, _code) _DEFINE_COMPILES_ASSERTION1 (_line, _code)
+# define DEFINE_COMPILES_ASSERTION(_code) _DEFINE_COMPILES_ASSERTION0 (__LINE__, _code)
+
+
+#define DEFINE_SIZE_STATIC(size) \
+ DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size)) \
+ unsigned int get_size () const { return (size); } \
+ static constexpr unsigned null_size = (size); \
+ static constexpr unsigned min_size = (size); \
+ static constexpr unsigned static_size = (size)
+
+#define DEFINE_SIZE_UNION(size, _member) \
+ DEFINE_COMPILES_ASSERTION ((void) this->u._member.static_size) \
+ DEFINE_INSTANCE_ASSERTION (sizeof(this->u._member) == (size)) \
+ static constexpr unsigned null_size = (size); \
+ static constexpr unsigned min_size = (size)
+
+#define DEFINE_SIZE_MIN(size) \
+ DEFINE_INSTANCE_ASSERTION (sizeof (*this) >= (size)) \
+ static constexpr unsigned null_size = (size); \
+ static constexpr unsigned min_size = (size)
+
+#define DEFINE_SIZE_UNBOUNDED(size) \
+ DEFINE_INSTANCE_ASSERTION (sizeof (*this) >= (size)) \
+ static constexpr unsigned min_size = (size)
+
+#define DEFINE_SIZE_ARRAY(size, array) \
+ DEFINE_COMPILES_ASSERTION ((void) (array)[0].static_size) \
+ DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size) + (HB_VAR_ARRAY+0) * sizeof ((array)[0])) \
+ static constexpr unsigned null_size = (size); \
+ static constexpr unsigned min_size = (size)
+
+#define DEFINE_SIZE_ARRAY_SIZED(size, array) \
+ unsigned int get_size () const { return (size - (array).min_size + (array).get_size ()); } \
+ DEFINE_SIZE_ARRAY(size, array)
+
+
+
+/*
+ * Lazy loaders.
+ *
+ * The lazy-loaders are thread-safe pointer-like objects that create their
+ * instead on-demand. They also support access to a "data" object that is
+ * necessary for creating their instance. The data object, if specified,
+ * is accessed via pointer math, located at a location before the position
+ * of the loader itself. This avoids having to store a pointer to data
+ * for every lazy-loader. Multiple lazy-loaders can access the same data.
+ */
+
+template <typename Data, unsigned int WheresData>
+struct hb_data_wrapper_t
+{
+ static_assert (WheresData > 0, "");
+
+ Data * get_data () const
+ { return *(((Data **) (void *) this) - WheresData); }
+
+ bool is_inert () const { return !get_data (); }
+
+ template <typename Stored, typename Subclass>
+ Stored * call_create () const { return Subclass::create (get_data ()); }
+};
+template <>
+struct hb_data_wrapper_t<void, 0>
+{
+ bool is_inert () const { return false; }
+
+ template <typename Stored, typename Funcs>
+ Stored * call_create () const { return Funcs::create (); }
+};
+
+template <typename T1, typename T2> struct hb_non_void_t { typedef T1 value; };
+template <typename T2> struct hb_non_void_t<void, T2> { typedef T2 value; };
+
+template <typename Returned,
+ typename Subclass = void,
+ typename Data = void,
+ unsigned int WheresData = 0,
+ typename Stored = Returned>
+struct hb_lazy_loader_t : hb_data_wrapper_t<Data, WheresData>
+{
+ typedef typename hb_non_void_t<Subclass,
+ hb_lazy_loader_t<Returned,Subclass,Data,WheresData,Stored>
+ >::value Funcs;
+
+ void init0 () {} /* Init, when memory is already set to 0. No-op for us. */
+ void init () { instance.set_relaxed (nullptr); }
+ void fini () { do_destroy (instance.get_acquire ()); init (); }
+
+ void free_instance ()
+ {
+ retry:
+ Stored *p = instance.get_acquire ();
+ if (unlikely (p && !cmpexch (p, nullptr)))
+ goto retry;
+ do_destroy (p);
+ }
+
+ static void do_destroy (Stored *p)
+ {
+ if (p && p != const_cast<Stored *> (Funcs::get_null ()))
+ Funcs::destroy (p);
+ }
+
+ const Returned * operator -> () const { return get (); }
+ template <typename U = Returned, hb_enable_if (!hb_is_same (U, void))>
+ const U & operator * () const { return *get (); }
+ explicit operator bool () const
+ { return get_stored () != Funcs::get_null (); }
+ template <typename C> operator const C * () const { return get (); }
+
+ Stored * get_stored () const
+ {
+ retry:
+ Stored *p = this->instance.get_acquire ();
+ if (unlikely (!p))
+ {
+ if (unlikely (this->is_inert ()))
+ return const_cast<Stored *> (Funcs::get_null ());
+
+ p = this->template call_create<Stored, Funcs> ();
+ if (unlikely (!p))
+ p = const_cast<Stored *> (Funcs::get_null ());
+
+ if (unlikely (!cmpexch (nullptr, p)))
+ {
+ do_destroy (p);
+ goto retry;
+ }
+ }
+ return p;
+ }
+ Stored * get_stored_relaxed () const
+ {
+ return this->instance.get_relaxed ();
+ }
+
+ bool cmpexch (Stored *current, Stored *value) const
+ {
+ /* This function can only be safely called directly if no
+ * other thread is accessing. */
+ return this->instance.cmpexch (current, value);
+ }
+
+ const Returned * get () const { return Funcs::convert (get_stored ()); }
+ const Returned * get_relaxed () const { return Funcs::convert (get_stored_relaxed ()); }
+ Returned * get_unconst () const { return const_cast<Returned *> (Funcs::convert (get_stored ())); }
+
+ /* To be possibly overloaded by subclasses. */
+ static Returned* convert (Stored *p) { return p; }
+
+ /* By default null/init/fini the object. */
+ static const Stored* get_null () { return &Null (Stored); }
+ static Stored *create (Data *data)
+ {
+ Stored *p = (Stored *) hb_calloc (1, sizeof (Stored));
+ if (likely (p))
+ p = new (p) Stored (data);
+ return p;
+ }
+ static Stored *create ()
+ {
+ Stored *p = (Stored *) hb_calloc (1, sizeof (Stored));
+ if (likely (p))
+ p = new (p) Stored ();
+ return p;
+ }
+ static void destroy (Stored *p)
+ {
+ p->~Stored ();
+ hb_free (p);
+ }
+
+ private:
+ /* Must only have one pointer. */
+ hb_atomic_ptr_t<Stored *> instance;
+};
+
+/* Specializations. */
+
+template <typename T, unsigned int WheresFace>
+struct hb_face_lazy_loader_t : hb_lazy_loader_t<T,
+ hb_face_lazy_loader_t<T, WheresFace>,
+ hb_face_t, WheresFace> {};
+
+template <typename T, unsigned int WheresFace, bool core=false>
+struct hb_table_lazy_loader_t : hb_lazy_loader_t<T,
+ hb_table_lazy_loader_t<T, WheresFace, core>,
+ hb_face_t, WheresFace,
+ hb_blob_t>
+{
+ static hb_blob_t *create (hb_face_t *face)
+ {
+ auto c = hb_sanitize_context_t ();
+ if (core)
+ c.set_num_glyphs (0); // So we don't recurse ad infinitum, or doesn't need num_glyphs
+ return c.reference_table<T> (face);
+ }
+ static void destroy (hb_blob_t *p) { hb_blob_destroy (p); }
+
+ static const hb_blob_t *get_null ()
+ { return hb_blob_get_empty (); }
+
+ static const T* convert (const hb_blob_t *blob)
+ { return blob->as<T> (); }
+
+ hb_blob_t* get_blob () const { return this->get_stored (); }
+};
+
+#define HB_DEFINE_TYPE_FUNCS_LAZY_LOADER_T(Type) \
+ template <typename Subclass> \
+ struct hb_##Type##_funcs_lazy_loader_t : hb_lazy_loader_t<hb_##Type##_funcs_t, Subclass> \
+ { \
+ static void destroy (hb_##Type##_funcs_t *p) \
+ { hb_##Type##_funcs_destroy (p); } \
+ static const hb_##Type##_funcs_t *get_null () \
+ { return hb_##Type##_funcs_get_empty (); } \
+ }
+
+HB_DEFINE_TYPE_FUNCS_LAZY_LOADER_T (font);
+HB_DEFINE_TYPE_FUNCS_LAZY_LOADER_T (unicode);
+HB_DEFINE_TYPE_FUNCS_LAZY_LOADER_T (draw);
+HB_DEFINE_TYPE_FUNCS_LAZY_LOADER_T (paint);
+
+#undef HB_DEFINE_TYPE_FUNCS_LAZY_LOADER_T
+
+
+#endif /* HB_MACHINERY_HH */