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1 /*
2  * Copyright © 2018  Google, Inc.
3  *
4  *  This is part of HarfBuzz, a text shaping library.
5  *
6  * Permission is hereby granted, without written agreement and without
7  * license or royalty fees, to use, copy, modify, and distribute this
8  * software and its documentation for any purpose, provided that the
9  * above copyright notice and the following two paragraphs appear in
10  * all copies of this software.
11  *
12  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
13  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
14  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
15  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
16  * DAMAGE.
17  *
18  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
19  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
20  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
21  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
22  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
23  *
24  * Google Author(s): Behdad Esfahbod
25  */
26 
27 #ifndef HB_ARRAY_HH
28 #define HB_ARRAY_HH
29 
30 #include "hb.hh"
31 #include "hb-algs.hh"
32 #include "hb-iter.hh"
33 #include "hb-null.hh"
34 
35 
36 template <typename Type>
37 struct hb_sorted_array_t;
38 
39 template <typename Type>
40 struct hb_array_t : hb_iter_with_fallback_t<hb_array_t<Type>, Type&>
41 {
42   /*
43    * Constructors.
44    */
hb_array_thb_array_t45   hb_array_t () : arrayZ (nullptr), length (0), backwards_length (0) {}
hb_array_thb_array_t46   hb_array_t (Type *array_, unsigned int length_) : arrayZ (array_), length (length_), backwards_length (0) {}
47   template <unsigned int length_>
hb_array_thb_array_t48   hb_array_t (Type (&array_)[length_]) : arrayZ (array_), length (length_), backwards_length (0) {}
49 
50   template <typename U,
51 	    hb_enable_if (hb_is_cr_convertible(U, Type))>
hb_array_thb_array_t52   hb_array_t (const hb_array_t<U> &o) :
53     hb_iter_with_fallback_t<hb_array_t, Type&> (),
54     arrayZ (o.arrayZ), length (o.length), backwards_length (o.backwards_length) {}
55   template <typename U,
56 	    hb_enable_if (hb_is_cr_convertible(U, Type))>
operator =hb_array_t57   hb_array_t& operator = (const hb_array_t<U> &o)
58   { arrayZ = o.arrayZ; length = o.length; backwards_length = o.backwards_length; return *this; }
59 
60   /*
61    * Iterator implementation.
62    */
63   typedef Type& __item_t__;
64   static constexpr bool is_random_access_iterator = true;
__item_at__hb_array_t65   Type& __item_at__ (unsigned i) const
66   {
67     if (unlikely (i >= length)) return CrapOrNull (Type);
68     return arrayZ[i];
69   }
__forward__hb_array_t70   void __forward__ (unsigned n)
71   {
72     if (unlikely (n > length))
73       n = length;
74     length -= n;
75     backwards_length += n;
76     arrayZ += n;
77   }
__rewind__hb_array_t78   void __rewind__ (unsigned n)
79   {
80     if (unlikely (n > backwards_length))
81       n = backwards_length;
82     length += n;
83     backwards_length -= n;
84     arrayZ -= n;
85   }
__len__hb_array_t86   unsigned __len__ () const { return length; }
87   /* Ouch. The operator== compares the contents of the array.  For range-based for loops,
88    * it's best if we can just compare arrayZ, though comparing contents is still fast,
89    * but also would require that Type has operator==.  As such, we optimize this operator
90    * for range-based for loop and just compare arrayZ.  No need to compare length, as we
91    * assume we're only compared to .end(). */
operator !=hb_array_t92   bool operator != (const hb_array_t& o) const
93   { return arrayZ != o.arrayZ; }
94 
95   /* Extra operators.
96    */
operator &hb_array_t97   Type * operator & () const { return arrayZ; }
operator hb_array_t<const Type>hb_array_t98   operator hb_array_t<const Type> () { return hb_array_t<const Type> (arrayZ, length); }
operator T*hb_array_t99   template <typename T> operator T * () const { return arrayZ; }
100 
101   HB_INTERNAL bool operator == (const hb_array_t &o) const;
102 
hashhb_array_t103   uint32_t hash () const {
104     uint32_t current = 0;
105     for (unsigned int i = 0; i < this->length; i++) {
106       current = current * 31 + hb_hash (this->arrayZ[i]);
107     }
108     return current;
109   }
110 
111   /*
112    * Compare, Sort, and Search.
113    */
114 
115   /* Note: our compare is NOT lexicographic; it also does NOT call Type::cmp. */
cmphb_array_t116   int cmp (const hb_array_t &a) const
117   {
118     if (length != a.length)
119       return (int) a.length - (int) length;
120     return hb_memcmp (a.arrayZ, arrayZ, get_size ());
121   }
cmphb_array_t122   HB_INTERNAL static int cmp (const void *pa, const void *pb)
123   {
124     hb_array_t *a = (hb_array_t *) pa;
125     hb_array_t *b = (hb_array_t *) pb;
126     return b->cmp (*a);
127   }
128 
129   template <typename T>
lsearchhb_array_t130   Type *lsearch (const T &x, Type *not_found = nullptr)
131   {
132     unsigned int count = length;
133     for (unsigned int i = 0; i < count; i++)
134       if (!this->arrayZ[i].cmp (x))
135 	return &this->arrayZ[i];
136     return not_found;
137   }
138   template <typename T>
lsearchhb_array_t139   const Type *lsearch (const T &x, const Type *not_found = nullptr) const
140   {
141     unsigned int count = length;
142     for (unsigned int i = 0; i < count; i++)
143       if (!this->arrayZ[i].cmp (x))
144 	return &this->arrayZ[i];
145     return not_found;
146   }
147 
qsorthb_array_t148   hb_sorted_array_t<Type> qsort (int (*cmp_)(const void*, const void*))
149   {
150     if (likely (length))
151       hb_qsort (arrayZ, length, this->get_item_size (), cmp_);
152     return hb_sorted_array_t<Type> (*this);
153   }
qsorthb_array_t154   hb_sorted_array_t<Type> qsort ()
155   {
156     if (likely (length))
157       hb_qsort (arrayZ, length, this->get_item_size (), Type::cmp);
158     return hb_sorted_array_t<Type> (*this);
159   }
qsorthb_array_t160   void qsort (unsigned int start, unsigned int end)
161   {
162     end = hb_min (end, length);
163     assert (start <= end);
164     if (likely (start < end))
165       hb_qsort (arrayZ + start, end - start, this->get_item_size (), Type::cmp);
166   }
167 
168   /*
169    * Other methods.
170    */
171 
get_sizehb_array_t172   unsigned int get_size () const { return length * this->get_item_size (); }
173 
sub_arrayhb_array_t174   hb_array_t sub_array (unsigned int start_offset = 0, unsigned int *seg_count = nullptr /* IN/OUT */) const
175   {
176     if (!start_offset && !seg_count)
177       return *this;
178 
179     unsigned int count = length;
180     if (unlikely (start_offset > count))
181       count = 0;
182     else
183       count -= start_offset;
184     if (seg_count)
185       count = *seg_count = hb_min (count, *seg_count);
186     return hb_array_t (arrayZ + start_offset, count);
187   }
sub_arrayhb_array_t188   hb_array_t sub_array (unsigned int start_offset, unsigned int seg_count) const
189   { return sub_array (start_offset, &seg_count); }
190 
truncatehb_array_t191   hb_array_t truncate (unsigned length) const { return sub_array (0, length); }
192 
193   template <typename T,
194 	    unsigned P = sizeof (Type),
195 	    hb_enable_if (P == 1)>
ashb_array_t196   const T *as () const
197   { return length < hb_null_size (T) ? &Null (T) : reinterpret_cast<const T *> (arrayZ); }
198 
199   template <typename T,
200 	    unsigned P = sizeof (Type),
201 	    hb_enable_if (P == 1)>
in_rangehb_array_t202   bool in_range (const T *p, unsigned int size = T::static_size) const
203   {
204     return ((const char *) p) >= arrayZ
205 	&& ((const char *) p + size) <= arrayZ + length;
206   }
207 
208   /* Only call if you allocated the underlying array using malloc() or similar. */
freehb_array_t209   void free ()
210   { ::free ((void *) arrayZ); arrayZ = nullptr; length = 0; }
211 
212   template <typename hb_serialize_context_t>
copyhb_array_t213   hb_array_t copy (hb_serialize_context_t *c) const
214   {
215     TRACE_SERIALIZE (this);
216     auto* out = c->start_embed (arrayZ);
217     if (unlikely (!c->extend_size (out, get_size ()))) return_trace (hb_array_t ());
218     for (unsigned i = 0; i < length; i++)
219       out[i] = arrayZ[i]; /* TODO: add version that calls c->copy() */
220     return_trace (hb_array_t (out, length));
221   }
222 
223   template <typename hb_sanitize_context_t>
sanitizehb_array_t224   bool sanitize (hb_sanitize_context_t *c) const
225   { return c->check_array (arrayZ, length); }
226 
227   /*
228    * Members
229    */
230 
231   public:
232   Type *arrayZ;
233   unsigned int length;
234   unsigned int backwards_length;
235 };
236 template <typename T> inline hb_array_t<T>
hb_array(T * array,unsigned int length)237 hb_array (T *array, unsigned int length)
238 { return hb_array_t<T> (array, length); }
239 template <typename T, unsigned int length_> inline hb_array_t<T>
hb_array(T (& array_)[length_])240 hb_array (T (&array_)[length_])
241 { return hb_array_t<T> (array_); }
242 
243 enum hb_bfind_not_found_t
244 {
245   HB_BFIND_NOT_FOUND_DONT_STORE,
246   HB_BFIND_NOT_FOUND_STORE,
247   HB_BFIND_NOT_FOUND_STORE_CLOSEST,
248 };
249 
250 template <typename Type>
251 struct hb_sorted_array_t :
252 	hb_iter_t<hb_sorted_array_t<Type>, Type&>,
253 	hb_array_t<Type>
254 {
255   typedef hb_iter_t<hb_sorted_array_t, Type&> iter_base_t;
256   HB_ITER_USING (iter_base_t);
257   static constexpr bool is_random_access_iterator = true;
258   static constexpr bool is_sorted_iterator = true;
259 
hb_sorted_array_thb_sorted_array_t260   hb_sorted_array_t () : hb_array_t<Type> () {}
hb_sorted_array_thb_sorted_array_t261   hb_sorted_array_t (Type *array_, unsigned int length_) : hb_array_t<Type> (array_, length_) {}
262   template <unsigned int length_>
hb_sorted_array_thb_sorted_array_t263   hb_sorted_array_t (Type (&array_)[length_]) : hb_array_t<Type> (array_) {}
264 
265   template <typename U,
266 	    hb_enable_if (hb_is_cr_convertible(U, Type))>
hb_sorted_array_thb_sorted_array_t267   hb_sorted_array_t (const hb_array_t<U> &o) :
268     hb_iter_t<hb_sorted_array_t, Type&> (),
269     hb_array_t<Type> (o) {}
270   template <typename U,
271 	    hb_enable_if (hb_is_cr_convertible(U, Type))>
operator =hb_sorted_array_t272   hb_sorted_array_t& operator = (const hb_array_t<U> &o)
273   { hb_array_t<Type> (*this) = o; return *this; }
274 
275   /* Iterator implementation. */
operator !=hb_sorted_array_t276   bool operator != (const hb_sorted_array_t& o) const
277   { return this->arrayZ != o.arrayZ || this->length != o.length; }
278 
sub_arrayhb_sorted_array_t279   hb_sorted_array_t sub_array (unsigned int start_offset, unsigned int *seg_count /* IN/OUT */) const
280   { return hb_sorted_array_t (((const hb_array_t<Type> *) (this))->sub_array (start_offset, seg_count)); }
sub_arrayhb_sorted_array_t281   hb_sorted_array_t sub_array (unsigned int start_offset, unsigned int seg_count) const
282   { return sub_array (start_offset, &seg_count); }
283 
truncatehb_sorted_array_t284   hb_sorted_array_t truncate (unsigned length) const { return sub_array (0, length); }
285 
286   template <typename T>
bsearchhb_sorted_array_t287   Type *bsearch (const T &x, Type *not_found = nullptr)
288   {
289     unsigned int i;
290     return bfind (x, &i) ? &this->arrayZ[i] : not_found;
291   }
292   template <typename T>
bsearchhb_sorted_array_t293   const Type *bsearch (const T &x, const Type *not_found = nullptr) const
294   {
295     unsigned int i;
296     return bfind (x, &i) ? &this->arrayZ[i] : not_found;
297   }
298   template <typename T>
bfindhb_sorted_array_t299   bool bfind (const T &x, unsigned int *i = nullptr,
300 	      hb_bfind_not_found_t not_found = HB_BFIND_NOT_FOUND_DONT_STORE,
301 	      unsigned int to_store = (unsigned int) -1) const
302   {
303     int min = 0, max = (int) this->length - 1;
304     const Type *array = this->arrayZ;
305     while (min <= max)
306     {
307       int mid = ((unsigned int) min + (unsigned int) max) / 2;
308       int c = array[mid].cmp (x);
309       if (c < 0)
310 	max = mid - 1;
311       else if (c > 0)
312 	min = mid + 1;
313       else
314       {
315 	if (i)
316 	  *i = mid;
317 	return true;
318       }
319     }
320     if (i)
321     {
322       switch (not_found)
323       {
324 	case HB_BFIND_NOT_FOUND_DONT_STORE:
325 	  break;
326 
327 	case HB_BFIND_NOT_FOUND_STORE:
328 	  *i = to_store;
329 	  break;
330 
331 	case HB_BFIND_NOT_FOUND_STORE_CLOSEST:
332 	  if (max < 0 || (max < (int) this->length && array[max].cmp (x) > 0))
333 	    max++;
334 	  *i = max;
335 	  break;
336       }
337     }
338     return false;
339   }
340 };
341 template <typename T> inline hb_sorted_array_t<T>
hb_sorted_array(T * array,unsigned int length)342 hb_sorted_array (T *array, unsigned int length)
343 { return hb_sorted_array_t<T> (array, length); }
344 template <typename T, unsigned int length_> inline hb_sorted_array_t<T>
hb_sorted_array(T (& array_)[length_])345 hb_sorted_array (T (&array_)[length_])
346 { return hb_sorted_array_t<T> (array_); }
347 
348 template <typename T>
operator ==(const hb_array_t<T> & o) const349 bool hb_array_t<T>::operator == (const hb_array_t<T> &o) const
350 {
351   if (o.length != this->length) return false;
352   for (unsigned int i = 0; i < this->length; i++) {
353     if (this->arrayZ[i] != o.arrayZ[i]) return false;
354   }
355   return true;
356 }
357 
358 /* TODO Specialize opeator== for hb_bytes_t and hb_ubytes_t. */
359 
360 template <>
hash() const361 inline uint32_t hb_array_t<const char>::hash () const {
362   uint32_t current = 0;
363   for (unsigned int i = 0; i < this->length; i++)
364     current = current * 31 + (uint32_t) (this->arrayZ[i] * 2654435761u);
365   return current;
366 }
367 
368 template <>
hash() const369 inline uint32_t hb_array_t<const unsigned char>::hash () const {
370   uint32_t current = 0;
371   for (unsigned int i = 0; i < this->length; i++)
372     current = current * 31 + (uint32_t) (this->arrayZ[i] * 2654435761u);
373   return current;
374 }
375 
376 
377 typedef hb_array_t<const char> hb_bytes_t;
378 typedef hb_array_t<const unsigned char> hb_ubytes_t;
379 
380 
381 
382 #endif /* HB_ARRAY_HH */
383