/*

 * Copyright © 2012,2017  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"

/*

 * hb_set_t

 */

/* TODO Keep a free-list so we can free pages that are completely zeroed.  At that

 * point maybe also use a sentinel value for "all-1" pages? */

struct hb_set_t

{

  struct page_map_t

  {

    inline int cmp (const page_map_t *o) const { return (int) o->major - (int) major; }

    uint32_t major;

    uint32_t index;

  };

  struct page_t

  {

    inline void init0 (void) { memset (&v, 0, sizeof (v)); }

    inline void init1 (void) { memset (&v, 0xff, sizeof (v)); }

    inline unsigned int len (void) const

    { return ARRAY_LENGTH_CONST (v); }

    inline bool is_empty (void) const

    {

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

        if (v[i])

          return false;

      return true;

    }

    inline void add (hb_codepoint_t g) { elt (g) |= mask (g); }

    inline void del (hb_codepoint_t g) { elt (g) &= ~mask (g); }

    inline bool has (hb_codepoint_t g) const { return !!(elt (g) & mask (g)); }

    inline void add_range (hb_codepoint_t a, hb_codepoint_t b)

    {

      elt_t *la = &elt (a);

      elt_t *lb = &elt (b);

      if (la == lb)

        *la |= (mask (b) << 1) - mask(a);

      else

      {

        *la |= ~(mask (a) - 1);

        la++;

        memset (la, 0xff, (char *) lb - (char *) la);

        *lb |= ((mask (b) << 1) - 1);

      }

    }

    inline bool is_equal (const page_t *other) const

    {

      return 0 == memcmp (&v, &other->v, sizeof (v));

    }

    inline unsigned int get_population (void) const

    {

      unsigned int pop = 0;

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

        pop += _hb_popcount (v[i]);

      return pop;

    }

    inline bool next (hb_codepoint_t *codepoint) const

    {

      unsigned int m = (*codepoint + 1) & MASK;

      if (!m)

      {

        *codepoint = INVALID;

        return false;

      }

      unsigned int i = m / ELT_BITS;

      unsigned int j = m & ELT_MASK;

      const elt_t vv = v[i] & ~((elt_t (1) << j) - 1);

      for (const elt_t *p = &vv; i < len (); p = &v[++i])

        if (*p)

        {

          *codepoint = i * ELT_BITS + elt_get_min (*p);

          return true;

        }

      *codepoint = INVALID;

      return false;

    }

    inline bool previous (hb_codepoint_t *codepoint) const

    {

      unsigned int m = (*codepoint - 1) & MASK;

      if (m == MASK)

      {

        *codepoint = INVALID;

        return false;

      }

      unsigned int i = m / ELT_BITS;

      unsigned int j = m & ELT_MASK;

      const elt_t vv = v[i] & ((elt_t (1) << (j + 1)) - 1);

      for (const elt_t *p = &vv; (int) i >= 0; p = &v[--i])

        if (*p)

        {

          *codepoint = i * ELT_BITS + elt_get_max (*p);

          return true;

        }

      *codepoint = INVALID;

      return false;

    }

    inline hb_codepoint_t get_min (void) const

    {

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

        if (v[i])

          return i * ELT_BITS + elt_get_min (v[i]);

      return INVALID;

    }

    inline hb_codepoint_t get_max (void) const

    {

      for (int i = len () - 1; i >= 0; i--)

        if (v[i])

          return i * ELT_BITS + elt_get_max (v[i]);

      return 0;

    }

    typedef unsigned long long elt_t;

    static_assert ((PAGE_BITS & ((PAGE_BITS) - 1)) == 0, "");

    static inline unsigned int elt_get_min (const elt_t &elt) { return _hb_ctz (elt); }

    static inline unsigned int elt_get_max (const elt_t &elt) { return _hb_bit_storage (elt) - 1; }

    typedef hb_vector_size_t<elt_t, PAGE_BITS / 8> vector_t;

    static const unsigned int ELT_BITS = sizeof (elt_t) * 8;

    static const unsigned int ELT_MASK = ELT_BITS - 1;

    static const unsigned int BITS = sizeof (vector_t) * 8;

    static const unsigned int MASK = BITS - 1;

    static_assert (PAGE_BITS == BITS, "");

    elt_t &elt (hb_codepoint_t g) { return v[(g & MASK) / ELT_BITS]; }

    elt_t const &elt (hb_codepoint_t g) const { return v[(g & MASK) / ELT_BITS]; }

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

  };

  static_assert (page_t::PAGE_BITS == sizeof (page_t) * 8, "");

  hb_object_header_t header;

  {

    page_map.init ();

    pages.init ();

  }

  {

  }

  inline bool resize (unsigned int count)

  {

    if (!pages.resize (count) || !page_map.resize (count))

    {

      pages.resize (page_map.len);

      return false;

    }

    return true;

  }

  inline void clear (void) {

    if (unlikely (hb_object_is_inert (this)))

      return;

    page_map.resize (0);

    pages.resize (0);

  }

  inline bool is_empty (void) const {

    unsigned int count = pages.len;

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

      if (!pages[i].is_empty ())

        return false;

    return true;

  }

  inline void add (hb_codepoint_t g)

  {

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

    page_t *page = page_for_insert (g); if (unlikely (!page)) return;

    page->add (g);

  }

  inline bool add_range (hb_codepoint_t a, hb_codepoint_t b)

  {

    if (unlikely (a > b || a == INVALID || b == INVALID)) return false;

    unsigned int ma = get_major (a);

    unsigned int mb = get_major (b);

    if (ma == mb)

    {

      page_t *page = page_for_insert (a); if (unlikely (!page)) return false;

      page->add_range (a, b);

    }

    else

    {

      page_t *page = page_for_insert (a); if (unlikely (!page)) return false;

      page->add_range (a, major_start (ma + 1) - 1);

      for (unsigned int m = ma + 1; m < mb; m++)

      {

        page = page_for_insert (major_start (m)); if (unlikely (!page)) return false;

        page->init1 ();

      }

      page = page_for_insert (b); if (unlikely (!page)) return false;

      page->add_range (major_start (mb), b);

    }

    return true;

  }

  template <typename T>

  inline void add_array (const T *array, unsigned int count, unsigned int stride=sizeof(T))

  {

    if (!count) return;

    hb_codepoint_t g = *array;

    while (count)

    {

      unsigned int m = get_major (g);

      page_t *page = page_for_insert (g); if (unlikely (!page)) return;

      unsigned int start = major_start (m);

      unsigned int end = major_start (m + 1);

      do

      {

        page->add (g);

        array = (const T *) ((const char *) array + stride);

        count--;

      }

      while (count && (g = *array, start <= g && g < end));

    }

  }

  /* Might return false if array looks unsorted.

   * Used for faster rejection of corrupt data. */

  template <typename T>

  inline bool add_sorted_array (const T *array, unsigned int count, unsigned int stride=sizeof(T))

  {

    if (!count) return true;

    hb_codepoint_t g = *array;

    hb_codepoint_t last_g = g;

    while (count)

    {

      unsigned int m = get_major (g);

      page_t *page = page_for_insert (g); if (unlikely (!page)) return false;

      unsigned int end = major_start (m + 1);

      do

      {

        /* If we try harder we can change the following comparison to <=;

         * Not sure if it's worth it. */

        if (g < last_g) return false;

        last_g = g;

        page->add (g);

        array = (const T *) ((const char *) array + stride);

        count--;

      }

      while (count && (g = *array, g < end));

    }

    return true;

  }

  inline void del (hb_codepoint_t g)

  {

    page_t *p = page_for (g);

    if (!p)

      return;

    p->del (g);

  }

  inline void del_range (hb_codepoint_t a, hb_codepoint_t b)

  {

    /* TODO Optimize, like add_range(). */

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

      del (i);

  }

  inline bool has (hb_codepoint_t g) const

  {

    const page_t *p = page_for (g);

    if (!p)

      return false;

    return p->has (g);

  }

  inline bool intersects (hb_codepoint_t first,

                          hb_codepoint_t last) const

  {

    hb_codepoint_t c = first - 1;

    return next (&c) && c <= last;

  }

  inline void set (const hb_set_t *other)

  {

    unsigned int count = other->pages.len;

    if (!resize (count))

      return;

  }

  inline bool is_equal (const hb_set_t *other) const

  {

    unsigned int na = pages.len;

    unsigned int nb = other->pages.len;

    unsigned int a = 0, b = 0;

    for (; a < na && b < nb; )

    {

      if (page_at (a).is_empty ()) { a++; continue; }

      if (other->page_at (b).is_empty ()) { b++; continue; }

      if (page_map[a].major != other->page_map[b].major ||

          !page_at (a).is_equal (&other->page_at (b)))

        return false;

      a++;

      b++;

    }

    for (; a < na; a++)

      if (!page_at (a).is_empty ()) { return false; }

    for (; b < nb; b++)

      if (!other->page_at (b).is_empty ()) { return false; }

    return true;

  }

  template <class Op>

  inline void process (const hb_set_t *other)

  {

    unsigned int na = pages.len;

    unsigned int nb = other->pages.len;

    unsigned int next_page = na;

    unsigned int a = 0, b = 0;

    for (; a < na && b < nb; )

    {

      if (page_map[a].major == other->page_map[b].major)

      {

        count++;

        a++;

        b++;

      }

      else if (page_map[a].major < other->page_map[b].major)

      {

        if (Op::passthru_left)

          count++;

        a++;

      }

      else

      {

        if (Op::passthru_right)

          count++;

        b++;

      }

    }

    if (Op::passthru_left)

      count += na - a;

    if (Op::passthru_right)

      count += nb - b;

    /* Process in-place backward. */

    a = na;

    b = nb;

    for (; a && b; )

    {

      if (page_map[a - 1].major == other->page_map[b - 1].major)

      {

        a--;

        b--;

        count--;

        page_map[count] = page_map[a];

        Op::process (page_at (count).v, page_at (a).v, other->page_at (b).v);

      }

      else if (page_map[a - 1].major > other->page_map[b - 1].major)

      {

        a--;

        if (Op::passthru_left)

        {

          count--;

          page_map[count] = page_map[a];

        }

      }

      else

      {

        b--;

        if (Op::passthru_right)

        {

          count--;

          page_map[count].major = other->page_map[b].major;

          page_map[count].index = next_page++;

          page_at (count).v = other->page_at (b).v;

        }

      }

    }