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 /*

  * Copyright © 2012  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.

  *

  * Google Author(s): Behdad Esfahbod

  */

 #ifndef HB_SET_PRIVATE_HH

 #define HB_SET_PRIVATE_HH

 #include "hb-private.hh"

 #include "hb-object-private.hh"

 /*

  * The set digests here implement various "filters" that support

  * "approximate member query".  Conceptually these are like Bloom

  * Filter and Quotient Filter, however, much smaller, faster, and

  * designed to fit the requirements of our uses for glyph coverage

  * queries.  As a result, our filters have much higher.

  */

 template <typename mask_t, unsigned int shift>

 struct hb_set_digest_lowest_bits_t

 {

   ASSERT_POD ();

   static const unsigned int mask_bytes = sizeof (mask_t);

   static const unsigned int mask_bits = sizeof (mask_t) * 8;

   static const unsigned int num_bits = 0

 				     + (mask_bytes >= 1 ? 3 : 0)

 				     + (mask_bytes >= 2 ? 1 : 0)

 				     + (mask_bytes >= 4 ? 1 : 0)

 				     + (mask_bytes >= 8 ? 1 : 0)

 				     + (mask_bytes >= 16? 1 : 0)

 				     + 0;

   ASSERT_STATIC (shift < sizeof (hb_codepoint_t) * 8);

   ASSERT_STATIC (shift + num_bits <= sizeof (hb_codepoint_t) * 8);

   inline void init (void) {

     mask = 0;

   }

   inline void add (hb_codepoint_t g) {

     mask |= mask_for (g);

   }

   inline void add_range (hb_codepoint_t a, hb_codepoint_t b) {

     if ((b >> shift) - (a >> shift) >= mask_bits - 1)

       mask = (mask_t) -1;

     else {

       mask_t ma = mask_for (a);

       mask_t mb = mask_for (b);

       mask |= mb + (mb - ma) - (mb < ma);

     }

   }

   inline bool may_have (hb_codepoint_t g) const {

     return !!(mask & mask_for (g));

   }

   private:

   static inline mask_t mask_for (hb_codepoint_t g) {

     return ((mask_t) 1) << ((g >> shift) & (mask_bits - 1));

   }

   mask_t mask;

 };

 template <typename head_t, typename tail_t>

 struct hb_set_digest_combiner_t

 {

   ASSERT_POD ();

   inline void init (void) {

     head.init ();

     tail.init ();

   }

   inline void add (hb_codepoint_t g) {

     head.add (g);

     tail.add (g);

   }

   inline void add_range (hb_codepoint_t a, hb_codepoint_t b) {

     head.add_range (a, b);

     tail.add_range (a, b);

   }

   inline bool may_have (hb_codepoint_t g) const {

     return head.may_have (g) && tail.may_have (g);

   }

   private:

   head_t head;

   tail_t tail;

 };

 /*

  * hb_set_digest_t

  *

  * This is a combination of digests that performs "best".

  * There is not much science to this: it's a result of intuition

  * and testing.

  */

 typedef hb_set_digest_combiner_t

 <

   hb_set_digest_lowest_bits_t<unsigned long, 4>,

   hb_set_digest_combiner_t

   <

     hb_set_digest_lowest_bits_t<unsigned long, 0>,

     hb_set_digest_lowest_bits_t<unsigned long, 9>

   >

 > hb_set_digest_t;

 /*

  * hb_set_t

  */

 /* TODO Make this faster and memmory efficient. */

 struct hb_set_t

 {

   hb_object_header_t header;

   ASSERT_POD ();

   bool in_error;

   inline void init (void) {

     header.init ();

     clear ();

   }

   inline void fini (void) {

   }

   inline void clear (void) {

     if (unlikely (hb_object_is_inert (this)))

       return;

     in_error = false;

     memset (elts, 0, sizeof elts);

   }

   inline bool is_empty (void) const {

     for (unsigned int i = 0; i < ARRAY_LENGTH (elts); i++)

       if (elts[i])

         return false;

     return true;

   }

   inline void add (hb_codepoint_t g)

   {

     if (unlikely (in_error)) return;

     if (unlikely (g == INVALID)) return;

     if (unlikely (g > MAX_G)) return;

     elt (g) |= mask (g);

   }

   inline void add_range (hb_codepoint_t a, hb_codepoint_t b)

   {

     if (unlikely (in_error)) return;

     /* TODO Speedup */

     for (unsigned int i = a; i < b + 1; i++)

       add (i);

   }

   inline void del (hb_codepoint_t g)

   {

     if (unlikely (in_error)) return;

     if (unlikely (g > MAX_G)) return;

     elt (g) &= ~mask (g);

   }

   inline void del_range (hb_codepoint_t a, hb_codepoint_t b)

   {

     if (unlikely (in_error)) return;

     /* TODO Speedup */

     for (unsigned int i = a; i < b + 1; i++)

       del (i);

   }

   inline bool has (hb_codepoint_t g) const

   {

     if (unlikely (g > MAX_G)) return false;

     return !!(elt (g) & mask (g));

   }

   inline bool intersects (hb_codepoint_t first,

 			  hb_codepoint_t last) const

   {

     if (unlikely (first > MAX_G)) return false;

     if (unlikely (last  > MAX_G)) last = MAX_G;

     unsigned int end = last + 1;

     for (hb_codepoint_t i = first; i < end; i++)

       if (has (i))

         return true;

     return false;

   }

   inline bool is_equal (const hb_set_t *other) const

   {

     for (unsigned int i = 0; i < ELTS; i++)

       if (elts[i] != other->elts[i])

         return false;

     return true;

   }

   inline void set (const hb_set_t *other)

   {

     if (unlikely (in_error)) return;

     for (unsigned int i = 0; i < ELTS; i++)

       elts[i] = other->elts[i];

   }

   inline void union_ (const hb_set_t *other)

   {

     if (unlikely (in_error)) return;

     for (unsigned int i = 0; i < ELTS; i++)

       elts[i] |= other->elts[i];

   }

   inline void intersect (const hb_set_t *other)

   {

     if (unlikely (in_error)) return;

     for (unsigned int i = 0; i < ELTS; i++)

       elts[i] &= other->elts[i];

   }

   inline void subtract (const hb_set_t *other)

   {

     if (unlikely (in_error)) return;

     for (unsigned int i = 0; i < ELTS; i++)

       elts[i] &= ~other->elts[i];

   }

   inline void symmetric_difference (const hb_set_t *other)

   {

     if (unlikely (in_error)) return;

     for (unsigned int i = 0; i < ELTS; i++)

       elts[i] ^= other->elts[i];

   }

   inline void invert (void)

   {

     if (unlikely (in_error)) return;

     for (unsigned int i = 0; i < ELTS; i++)

       elts[i] = ~elts[i];

   }

   inline bool next (hb_codepoint_t *codepoint) const

   {

     if (unlikely (*codepoint == INVALID)) {

       hb_codepoint_t i = get_min ();

       if (i != INVALID) {

         *codepoint = i;

 	return true;

       } else {

 	*codepoint = INVALID;

         return false;

       }

     }

     for (hb_codepoint_t i = *codepoint + 1; i < MAX_G + 1; i++)

       if (has (i)) {

         *codepoint = i;

 	return true;

       }

     *codepoint = INVALID;

     return false;

   }

   inline bool next_range (hb_codepoint_t *first, hb_codepoint_t *last) const

   {

     hb_codepoint_t i;

     i = *last;

     if (!next (&i))

     {

       *last = *first = INVALID;

       return false;

     }

     *last = *first = i;

     while (next (&i) && i == *last + 1)

       (*last)++;

     return true;

   }

   inline unsigned int get_population (void) const

   {

     unsigned int count = 0;

     for (unsigned int i = 0; i < ELTS; i++)

       count += _hb_popcount32 (elts[i]);

     return count;

   }

   inline hb_codepoint_t get_min (void) const

   {

     for (unsigned int i = 0; i < ELTS; i++)

       if (elts[i])

 	for (unsigned int j = 0; j < BITS; j++)

 	  if (elts[i] & (1 << j))

 	    return i * BITS + j;

     return INVALID;

   }

   inline hb_codepoint_t get_max (void) const

   {

     for (unsigned int i = ELTS; i; i--)

       if (elts[i - 1])

 	for (unsigned int j = BITS; j; j--)

 	  if (elts[i - 1] & (1 << (j - 1)))

 	    return (i - 1) * BITS + (j - 1);

     return INVALID;

   }

   typedef uint32_t elt_t;

   static const unsigned int MAX_G = 65536 - 1; /* XXX Fix this... */

   static const unsigned int SHIFT = 5;

   static const unsigned int BITS = (1 << SHIFT);

   static const unsigned int MASK = BITS - 1;

   static const unsigned int ELTS = (MAX_G + 1 + (BITS - 1)) / BITS;

   static  const hb_codepoint_t INVALID = HB_SET_VALUE_INVALID;

   elt_t &elt (hb_codepoint_t g) { return elts[g >> SHIFT]; }

   elt_t elt (hb_codepoint_t g) const { return elts[g >> SHIFT]; }

   elt_t mask (hb_codepoint_t g) const { return elt_t (1) << (g & MASK); }

   elt_t elts[ELTS]; /* XXX 8kb */

   ASSERT_STATIC (sizeof (elt_t) * 8 == BITS);

   ASSERT_STATIC (sizeof (elt_t) * 8 * ELTS > MAX_G);

 };

 #endif /* HB_SET_PRIVATE_HH */