michael@0: /*
michael@0:  * Copyright © 2012  Google, Inc.
michael@0:  *
michael@0:  *  This is part of HarfBuzz, a text shaping library.
michael@0:  *
michael@0:  * Permission is hereby granted, without written agreement and without
michael@0:  * license or royalty fees, to use, copy, modify, and distribute this
michael@0:  * software and its documentation for any purpose, provided that the
michael@0:  * above copyright notice and the following two paragraphs appear in
michael@0:  * all copies of this software.
michael@0:  *
michael@0:  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
michael@0:  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
michael@0:  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
michael@0:  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
michael@0:  * DAMAGE.
michael@0:  *
michael@0:  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
michael@0:  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
michael@0:  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
michael@0:  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
michael@0:  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
michael@0:  *
michael@0:  * Google Author(s): Behdad Esfahbod
michael@0:  */
michael@0: 
michael@0: #ifndef HB_SET_PRIVATE_HH
michael@0: #define HB_SET_PRIVATE_HH
michael@0: 
michael@0: #include "hb-private.hh"
michael@0: #include "hb-object-private.hh"
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * The set digests here implement various "filters" that support
michael@0:  * "approximate member query".  Conceptually these are like Bloom
michael@0:  * Filter and Quotient Filter, however, much smaller, faster, and
michael@0:  * designed to fit the requirements of our uses for glyph coverage
michael@0:  * queries.  As a result, our filters have much higher.
michael@0:  */
michael@0: 
michael@0: template <typename mask_t, unsigned int shift>
michael@0: struct hb_set_digest_lowest_bits_t
michael@0: {
michael@0:   ASSERT_POD ();
michael@0: 
michael@0:   static const unsigned int mask_bytes = sizeof (mask_t);
michael@0:   static const unsigned int mask_bits = sizeof (mask_t) * 8;
michael@0:   static const unsigned int num_bits = 0
michael@0: 				     + (mask_bytes >= 1 ? 3 : 0)
michael@0: 				     + (mask_bytes >= 2 ? 1 : 0)
michael@0: 				     + (mask_bytes >= 4 ? 1 : 0)
michael@0: 				     + (mask_bytes >= 8 ? 1 : 0)
michael@0: 				     + (mask_bytes >= 16? 1 : 0)
michael@0: 				     + 0;
michael@0: 
michael@0:   ASSERT_STATIC (shift < sizeof (hb_codepoint_t) * 8);
michael@0:   ASSERT_STATIC (shift + num_bits <= sizeof (hb_codepoint_t) * 8);
michael@0: 
michael@0:   inline void init (void) {
michael@0:     mask = 0;
michael@0:   }
michael@0: 
michael@0:   inline void add (hb_codepoint_t g) {
michael@0:     mask |= mask_for (g);
michael@0:   }
michael@0: 
michael@0:   inline void add_range (hb_codepoint_t a, hb_codepoint_t b) {
michael@0:     if ((b >> shift) - (a >> shift) >= mask_bits - 1)
michael@0:       mask = (mask_t) -1;
michael@0:     else {
michael@0:       mask_t ma = mask_for (a);
michael@0:       mask_t mb = mask_for (b);
michael@0:       mask |= mb + (mb - ma) - (mb < ma);
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   inline bool may_have (hb_codepoint_t g) const {
michael@0:     return !!(mask & mask_for (g));
michael@0:   }
michael@0: 
michael@0:   private:
michael@0: 
michael@0:   static inline mask_t mask_for (hb_codepoint_t g) {
michael@0:     return ((mask_t) 1) << ((g >> shift) & (mask_bits - 1));
michael@0:   }
michael@0:   mask_t mask;
michael@0: };
michael@0: 
michael@0: template <typename head_t, typename tail_t>
michael@0: struct hb_set_digest_combiner_t
michael@0: {
michael@0:   ASSERT_POD ();
michael@0: 
michael@0:   inline void init (void) {
michael@0:     head.init ();
michael@0:     tail.init ();
michael@0:   }
michael@0: 
michael@0:   inline void add (hb_codepoint_t g) {
michael@0:     head.add (g);
michael@0:     tail.add (g);
michael@0:   }
michael@0: 
michael@0:   inline void add_range (hb_codepoint_t a, hb_codepoint_t b) {
michael@0:     head.add_range (a, b);
michael@0:     tail.add_range (a, b);
michael@0:   }
michael@0: 
michael@0:   inline bool may_have (hb_codepoint_t g) const {
michael@0:     return head.may_have (g) && tail.may_have (g);
michael@0:   }
michael@0: 
michael@0:   private:
michael@0:   head_t head;
michael@0:   tail_t tail;
michael@0: };
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * hb_set_digest_t
michael@0:  *
michael@0:  * This is a combination of digests that performs "best".
michael@0:  * There is not much science to this: it's a result of intuition
michael@0:  * and testing.
michael@0:  */
michael@0: typedef hb_set_digest_combiner_t
michael@0: <
michael@0:   hb_set_digest_lowest_bits_t<unsigned long, 4>,
michael@0:   hb_set_digest_combiner_t
michael@0:   <
michael@0:     hb_set_digest_lowest_bits_t<unsigned long, 0>,
michael@0:     hb_set_digest_lowest_bits_t<unsigned long, 9>
michael@0:   >
michael@0: > hb_set_digest_t;
michael@0: 
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * hb_set_t
michael@0:  */
michael@0: 
michael@0: 
michael@0: /* TODO Make this faster and memmory efficient. */
michael@0: 
michael@0: struct hb_set_t
michael@0: {
michael@0:   hb_object_header_t header;
michael@0:   ASSERT_POD ();
michael@0:   bool in_error;
michael@0: 
michael@0:   inline void init (void) {
michael@0:     header.init ();
michael@0:     clear ();
michael@0:   }
michael@0:   inline void fini (void) {
michael@0:   }
michael@0:   inline void clear (void) {
michael@0:     if (unlikely (hb_object_is_inert (this)))
michael@0:       return;
michael@0:     in_error = false;
michael@0:     memset (elts, 0, sizeof elts);
michael@0:   }
michael@0:   inline bool is_empty (void) const {
michael@0:     for (unsigned int i = 0; i < ARRAY_LENGTH (elts); i++)
michael@0:       if (elts[i])
michael@0:         return false;
michael@0:     return true;
michael@0:   }
michael@0:   inline void add (hb_codepoint_t g)
michael@0:   {
michael@0:     if (unlikely (in_error)) return;
michael@0:     if (unlikely (g == INVALID)) return;
michael@0:     if (unlikely (g > MAX_G)) return;
michael@0:     elt (g) |= mask (g);
michael@0:   }
michael@0:   inline void add_range (hb_codepoint_t a, hb_codepoint_t b)
michael@0:   {
michael@0:     if (unlikely (in_error)) return;
michael@0:     /* TODO Speedup */
michael@0:     for (unsigned int i = a; i < b + 1; i++)
michael@0:       add (i);
michael@0:   }
michael@0:   inline void del (hb_codepoint_t g)
michael@0:   {
michael@0:     if (unlikely (in_error)) return;
michael@0:     if (unlikely (g > MAX_G)) return;
michael@0:     elt (g) &= ~mask (g);
michael@0:   }
michael@0:   inline void del_range (hb_codepoint_t a, hb_codepoint_t b)
michael@0:   {
michael@0:     if (unlikely (in_error)) return;
michael@0:     /* TODO Speedup */
michael@0:     for (unsigned int i = a; i < b + 1; i++)
michael@0:       del (i);
michael@0:   }
michael@0:   inline bool has (hb_codepoint_t g) const
michael@0:   {
michael@0:     if (unlikely (g > MAX_G)) return false;
michael@0:     return !!(elt (g) & mask (g));
michael@0:   }
michael@0:   inline bool intersects (hb_codepoint_t first,
michael@0: 			  hb_codepoint_t last) const
michael@0:   {
michael@0:     if (unlikely (first > MAX_G)) return false;
michael@0:     if (unlikely (last  > MAX_G)) last = MAX_G;
michael@0:     unsigned int end = last + 1;
michael@0:     for (hb_codepoint_t i = first; i < end; i++)
michael@0:       if (has (i))
michael@0:         return true;
michael@0:     return false;
michael@0:   }
michael@0:   inline bool is_equal (const hb_set_t *other) const
michael@0:   {
michael@0:     for (unsigned int i = 0; i < ELTS; i++)
michael@0:       if (elts[i] != other->elts[i])
michael@0:         return false;
michael@0:     return true;
michael@0:   }
michael@0:   inline void set (const hb_set_t *other)
michael@0:   {
michael@0:     if (unlikely (in_error)) return;
michael@0:     for (unsigned int i = 0; i < ELTS; i++)
michael@0:       elts[i] = other->elts[i];
michael@0:   }
michael@0:   inline void union_ (const hb_set_t *other)
michael@0:   {
michael@0:     if (unlikely (in_error)) return;
michael@0:     for (unsigned int i = 0; i < ELTS; i++)
michael@0:       elts[i] |= other->elts[i];
michael@0:   }
michael@0:   inline void intersect (const hb_set_t *other)
michael@0:   {
michael@0:     if (unlikely (in_error)) return;
michael@0:     for (unsigned int i = 0; i < ELTS; i++)
michael@0:       elts[i] &= other->elts[i];
michael@0:   }
michael@0:   inline void subtract (const hb_set_t *other)
michael@0:   {
michael@0:     if (unlikely (in_error)) return;
michael@0:     for (unsigned int i = 0; i < ELTS; i++)
michael@0:       elts[i] &= ~other->elts[i];
michael@0:   }
michael@0:   inline void symmetric_difference (const hb_set_t *other)
michael@0:   {
michael@0:     if (unlikely (in_error)) return;
michael@0:     for (unsigned int i = 0; i < ELTS; i++)
michael@0:       elts[i] ^= other->elts[i];
michael@0:   }
michael@0:   inline void invert (void)
michael@0:   {
michael@0:     if (unlikely (in_error)) return;
michael@0:     for (unsigned int i = 0; i < ELTS; i++)
michael@0:       elts[i] = ~elts[i];
michael@0:   }
michael@0:   inline bool next (hb_codepoint_t *codepoint) const
michael@0:   {
michael@0:     if (unlikely (*codepoint == INVALID)) {
michael@0:       hb_codepoint_t i = get_min ();
michael@0:       if (i != INVALID) {
michael@0:         *codepoint = i;
michael@0: 	return true;
michael@0:       } else {
michael@0: 	*codepoint = INVALID;
michael@0:         return false;
michael@0:       }
michael@0:     }
michael@0:     for (hb_codepoint_t i = *codepoint + 1; i < MAX_G + 1; i++)
michael@0:       if (has (i)) {
michael@0:         *codepoint = i;
michael@0: 	return true;
michael@0:       }
michael@0:     *codepoint = INVALID;
michael@0:     return false;
michael@0:   }
michael@0:   inline bool next_range (hb_codepoint_t *first, hb_codepoint_t *last) const
michael@0:   {
michael@0:     hb_codepoint_t i;
michael@0: 
michael@0:     i = *last;
michael@0:     if (!next (&i))
michael@0:     {
michael@0:       *last = *first = INVALID;
michael@0:       return false;
michael@0:     }
michael@0: 
michael@0:     *last = *first = i;
michael@0:     while (next (&i) && i == *last + 1)
michael@0:       (*last)++;
michael@0: 
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0:   inline unsigned int get_population (void) const
michael@0:   {
michael@0:     unsigned int count = 0;
michael@0:     for (unsigned int i = 0; i < ELTS; i++)
michael@0:       count += _hb_popcount32 (elts[i]);
michael@0:     return count;
michael@0:   }
michael@0:   inline hb_codepoint_t get_min (void) const
michael@0:   {
michael@0:     for (unsigned int i = 0; i < ELTS; i++)
michael@0:       if (elts[i])
michael@0: 	for (unsigned int j = 0; j < BITS; j++)
michael@0: 	  if (elts[i] & (1 << j))
michael@0: 	    return i * BITS + j;
michael@0:     return INVALID;
michael@0:   }
michael@0:   inline hb_codepoint_t get_max (void) const
michael@0:   {
michael@0:     for (unsigned int i = ELTS; i; i--)
michael@0:       if (elts[i - 1])
michael@0: 	for (unsigned int j = BITS; j; j--)
michael@0: 	  if (elts[i - 1] & (1 << (j - 1)))
michael@0: 	    return (i - 1) * BITS + (j - 1);
michael@0:     return INVALID;
michael@0:   }
michael@0: 
michael@0:   typedef uint32_t elt_t;
michael@0:   static const unsigned int MAX_G = 65536 - 1; /* XXX Fix this... */
michael@0:   static const unsigned int SHIFT = 5;
michael@0:   static const unsigned int BITS = (1 << SHIFT);
michael@0:   static const unsigned int MASK = BITS - 1;
michael@0:   static const unsigned int ELTS = (MAX_G + 1 + (BITS - 1)) / BITS;
michael@0:   static  const hb_codepoint_t INVALID = HB_SET_VALUE_INVALID;
michael@0: 
michael@0:   elt_t &elt (hb_codepoint_t g) { return elts[g >> SHIFT]; }
michael@0:   elt_t elt (hb_codepoint_t g) const { return elts[g >> SHIFT]; }
michael@0:   elt_t mask (hb_codepoint_t g) const { return elt_t (1) << (g & MASK); }
michael@0: 
michael@0:   elt_t elts[ELTS]; /* XXX 8kb */
michael@0: 
michael@0:   ASSERT_STATIC (sizeof (elt_t) * 8 == BITS);
michael@0:   ASSERT_STATIC (sizeof (elt_t) * 8 * ELTS > MAX_G);
michael@0: };
michael@0: 
michael@0: 
michael@0: 
michael@0: #endif /* HB_SET_PRIVATE_HH */