319 lines
10 KiB
C++
319 lines
10 KiB
C++
/*
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* Copyright © 2007,2008,2009,2010 Red Hat, Inc.
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* Copyright © 2012,2018 Google, Inc.
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*
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* This is part of HarfBuzz, a text shaping library.
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*
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* Permission is hereby granted, without written agreement and without
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* license or royalty fees, to use, copy, modify, and distribute this
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* software and its documentation for any purpose, provided that the
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* above copyright notice and the following two paragraphs appear in
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* all copies of this software.
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*
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* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
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* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
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* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*
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* Red Hat Author(s): Behdad Esfahbod
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* Google Author(s): Behdad Esfahbod
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*/
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#ifndef HB_MACHINERY_HH
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#define HB_MACHINERY_HH
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#include "hb.hh"
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#include "hb-blob.hh"
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#include "hb-dispatch.hh"
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#include "hb-sanitize.hh"
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#include "hb-serialize.hh"
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/*
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* Casts
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*/
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/* StructAtOffset<T>(P,Ofs) returns the struct T& that is placed at memory
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* location pointed to by P plus Ofs bytes. */
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template<typename Type>
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static inline const Type& StructAtOffset(const void *P, unsigned int offset)
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{ return * reinterpret_cast<const Type*> ((const char *) P + offset); }
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template<typename Type>
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static inline Type& StructAtOffset(void *P, unsigned int offset)
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{ return * reinterpret_cast<Type*> ((char *) P + offset); }
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template<typename Type>
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static inline const Type& StructAtOffsetUnaligned(const void *P, unsigned int offset)
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{
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wcast-align"
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return * reinterpret_cast<const Type*> ((const char *) P + offset);
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#pragma GCC diagnostic pop
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}
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template<typename Type>
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static inline Type& StructAtOffsetUnaligned(void *P, unsigned int offset)
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{
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wcast-align"
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return * reinterpret_cast<Type*> ((char *) P + offset);
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#pragma GCC diagnostic pop
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}
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/* StructAfter<T>(X) returns the struct T& that is placed after X.
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* Works with X of variable size also. X must implement get_size() */
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template<typename Type, typename TObject>
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static inline const Type& StructAfter(const TObject &X)
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{ return StructAtOffset<Type>(&X, X.get_size()); }
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template<typename Type, typename TObject>
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static inline Type& StructAfter(TObject &X)
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{ return StructAtOffset<Type>(&X, X.get_size()); }
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/*
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* Size checking
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*/
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/* Size signifying variable-sized array */
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#ifndef HB_VAR_ARRAY
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#define HB_VAR_ARRAY 1
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#endif
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/* Check _assertion in a method environment */
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#define _DEFINE_INSTANCE_ASSERTION1(_line, _assertion) \
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void _instance_assertion_on_line_##_line () const \
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{ static_assert ((_assertion), ""); }
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# define _DEFINE_INSTANCE_ASSERTION0(_line, _assertion) _DEFINE_INSTANCE_ASSERTION1 (_line, _assertion)
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# define DEFINE_INSTANCE_ASSERTION(_assertion) _DEFINE_INSTANCE_ASSERTION0 (__LINE__, _assertion)
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/* Check that _code compiles in a method environment */
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#define _DEFINE_COMPILES_ASSERTION1(_line, _code) \
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void _compiles_assertion_on_line_##_line () const \
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{ _code; }
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# define _DEFINE_COMPILES_ASSERTION0(_line, _code) _DEFINE_COMPILES_ASSERTION1 (_line, _code)
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# define DEFINE_COMPILES_ASSERTION(_code) _DEFINE_COMPILES_ASSERTION0 (__LINE__, _code)
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#define DEFINE_SIZE_STATIC(size) \
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DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size)) \
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unsigned int get_size () const { return (size); } \
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static constexpr unsigned null_size = (size); \
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static constexpr unsigned min_size = (size); \
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static constexpr unsigned static_size = (size)
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#define DEFINE_SIZE_UNION(size, _member) \
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DEFINE_COMPILES_ASSERTION ((void) this->u._member.static_size) \
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DEFINE_INSTANCE_ASSERTION (sizeof(this->u._member) == (size)) \
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static constexpr unsigned null_size = (size); \
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static constexpr unsigned min_size = (size)
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#define DEFINE_SIZE_MIN(size) \
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DEFINE_INSTANCE_ASSERTION (sizeof (*this) >= (size)) \
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static constexpr unsigned null_size = (size); \
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static constexpr unsigned min_size = (size)
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#define DEFINE_SIZE_UNBOUNDED(size) \
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DEFINE_INSTANCE_ASSERTION (sizeof (*this) >= (size)) \
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static constexpr unsigned min_size = (size)
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#define DEFINE_SIZE_ARRAY(size, array) \
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DEFINE_COMPILES_ASSERTION ((void) (array)[0].static_size) \
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DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size) + (HB_VAR_ARRAY+0) * sizeof ((array)[0])) \
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static constexpr unsigned null_size = (size); \
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static constexpr unsigned min_size = (size)
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#define DEFINE_SIZE_ARRAY_SIZED(size, array) \
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unsigned int get_size () const { return (size - (array).min_size + (array).get_size ()); } \
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DEFINE_SIZE_ARRAY(size, array)
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/*
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* Lazy loaders.
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*/
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template <typename Data, unsigned int WheresData>
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struct hb_data_wrapper_t
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{
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static_assert (WheresData > 0, "");
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Data * get_data () const
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{ return *(((Data **) (void *) this) - WheresData); }
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bool is_inert () const { return !get_data (); }
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template <typename Stored, typename Subclass>
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Stored * call_create () const { return Subclass::create (get_data ()); }
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};
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template <>
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struct hb_data_wrapper_t<void, 0>
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{
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bool is_inert () const { return false; }
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template <typename Stored, typename Funcs>
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Stored * call_create () const { return Funcs::create (); }
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};
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template <typename T1, typename T2> struct hb_non_void_t { typedef T1 value; };
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template <typename T2> struct hb_non_void_t<void, T2> { typedef T2 value; };
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template <typename Returned,
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typename Subclass = void,
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typename Data = void,
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unsigned int WheresData = 0,
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typename Stored = Returned>
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struct hb_lazy_loader_t : hb_data_wrapper_t<Data, WheresData>
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{
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typedef typename hb_non_void_t<Subclass,
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hb_lazy_loader_t<Returned,Subclass,Data,WheresData,Stored>
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>::value Funcs;
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void init0 () {} /* Init, when memory is already set to 0. No-op for us. */
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void init () { instance.set_relaxed (nullptr); }
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void fini () { do_destroy (instance.get ()); }
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void free_instance ()
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{
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retry:
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Stored *p = instance.get ();
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if (unlikely (p && !cmpexch (p, nullptr)))
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goto retry;
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do_destroy (p);
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}
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static void do_destroy (Stored *p)
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{
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if (p && p != const_cast<Stored *> (Funcs::get_null ()))
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Funcs::destroy (p);
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}
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const Returned * operator -> () const { return get (); }
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template <typename U = Returned, hb_enable_if (!hb_is_same (U, void))>
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const U & operator * () const { return *get (); }
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explicit operator bool () const
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{ return get_stored () != Funcs::get_null (); }
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template <typename C> operator const C * () const { return get (); }
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Stored * get_stored () const
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{
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retry:
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Stored *p = this->instance.get ();
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if (unlikely (!p))
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{
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if (unlikely (this->is_inert ()))
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return const_cast<Stored *> (Funcs::get_null ());
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p = this->template call_create<Stored, Funcs> ();
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if (unlikely (!p))
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p = const_cast<Stored *> (Funcs::get_null ());
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if (unlikely (!cmpexch (nullptr, p)))
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{
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do_destroy (p);
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goto retry;
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}
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}
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return p;
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}
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Stored * get_stored_relaxed () const
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{
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return this->instance.get_relaxed ();
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}
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bool cmpexch (Stored *current, Stored *value) const
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{
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/* This *must* be called when there are no other threads accessing. */
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return this->instance.cmpexch (current, value);
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}
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const Returned * get () const { return Funcs::convert (get_stored ()); }
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const Returned * get_relaxed () const { return Funcs::convert (get_stored_relaxed ()); }
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Returned * get_unconst () const { return const_cast<Returned *> (Funcs::convert (get_stored ())); }
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/* To be possibly overloaded by subclasses. */
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static Returned* convert (Stored *p) { return p; }
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/* By default null/init/fini the object. */
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static const Stored* get_null () { return &Null (Stored); }
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static Stored *create (Data *data)
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{
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Stored *p = (Stored *) hb_calloc (1, sizeof (Stored));
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if (likely (p))
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p = new (p) Stored (data);
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return p;
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}
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static Stored *create ()
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{
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Stored *p = (Stored *) hb_calloc (1, sizeof (Stored));
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if (likely (p))
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p = new (p) Stored ();
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return p;
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}
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static void destroy (Stored *p)
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{
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p->~Stored ();
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hb_free (p);
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}
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// private:
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/* Must only have one pointer. */
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hb_atomic_ptr_t<Stored *> instance;
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};
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/* Specializations. */
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template <typename T, unsigned int WheresFace>
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struct hb_face_lazy_loader_t : hb_lazy_loader_t<T,
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hb_face_lazy_loader_t<T, WheresFace>,
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hb_face_t, WheresFace> {};
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template <typename T, unsigned int WheresFace, bool core=false>
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struct hb_table_lazy_loader_t : hb_lazy_loader_t<T,
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hb_table_lazy_loader_t<T, WheresFace, core>,
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hb_face_t, WheresFace,
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hb_blob_t>
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{
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static hb_blob_t *create (hb_face_t *face)
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{
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auto c = hb_sanitize_context_t ();
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if (core)
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c.set_num_glyphs (0); // So we don't recurse ad infinitum...
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return c.reference_table<T> (face);
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}
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static void destroy (hb_blob_t *p) { hb_blob_destroy (p); }
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static const hb_blob_t *get_null ()
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{ return hb_blob_get_empty (); }
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static const T* convert (const hb_blob_t *blob)
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{ return blob->as<T> (); }
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hb_blob_t* get_blob () const { return this->get_stored (); }
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};
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template <typename Subclass>
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struct hb_font_funcs_lazy_loader_t : hb_lazy_loader_t<hb_font_funcs_t, Subclass>
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{
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static void destroy (hb_font_funcs_t *p)
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{ hb_font_funcs_destroy (p); }
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static const hb_font_funcs_t *get_null ()
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{ return hb_font_funcs_get_empty (); }
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};
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template <typename Subclass>
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struct hb_unicode_funcs_lazy_loader_t : hb_lazy_loader_t<hb_unicode_funcs_t, Subclass>
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{
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static void destroy (hb_unicode_funcs_t *p)
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{ hb_unicode_funcs_destroy (p); }
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static const hb_unicode_funcs_t *get_null ()
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{ return hb_unicode_funcs_get_empty (); }
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};
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#endif /* HB_MACHINERY_HH */
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