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/*
 * Copyright 漏 2018  Ebrahim Byagowi
 *
 *  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.
 */

#ifndef HB_AAT_LAYOUT_FEAT_TABLE_HH
#define HB_AAT_LAYOUT_FEAT_TABLE_HH

#include "hb-aat-layout-common.hh"

/*
 * feat -- Feature Name
 * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6feat.html
 */
#define HB_AAT_TAG_feat HB_TAG('f','e','a','t')


namespace AAT {


struct SettingName
{
  friend struct FeatureName;

  int cmp (hb_aat_layout_feature_selector_t key) const
  { return (int) key - (int) setting; }

  hb_aat_layout_feature_selector_t get_selector () const
  { return (hb_aat_layout_feature_selector_t) (unsigned) setting; }

  void get_info (hb_aat_layout_feature_selector_info_t *s,
                        hb_aat_layout_feature_selector_t default_selector) const
  {
    s->name_id = nameIndex;

    s->enable = (hb_aat_layout_feature_selector_t) (unsigned int) setting;
    s->disable = default_selector == HB_AAT_LAYOUT_FEATURE_SELECTOR_INVALID ?
                 (hb_aat_layout_feature_selector_t) (s->enable + 1) :
                 default_selector;

    s->reserved = 0;
  }

  bool sanitize (hb_sanitize_context_t *c) const
  {
    TRACE_SANITIZE (this);
    return_trace (likely (c->check_struct (this)));
  }

  protected:
  HBUINT16      setting;        /* The setting. */
  NameID        nameIndex;      /* The name table index for the setting's name. */
  public:
  DEFINE_SIZE_STATIC (4);
};
DECLARE_NULL_NAMESPACE_BYTES (AAT, SettingName);

struct feat;

struct FeatureName
{
  int cmp (hb_aat_layout_feature_type_t key) const
  { return (int) key - (int) feature; }

  enum {
    Exclusive   = 0x8000,       /* If set, the feature settings are mutually exclusive. */
    NotDefault  = 0x4000,       /* If clear, then the setting with an index of 0 in
                                 * the setting name array for this feature should
                                 * be taken as the default for the feature
                                 * (if one is required). If set, then bits 0-15 of this
                                 * featureFlags field contain the index of the setting
                                 * which is to be taken as the default. */
    IndexMask   = 0x00FF        /* If bits 30 and 31 are set, then these sixteen bits
                                 * indicate the index of the setting in the setting name
                                 * array for this feature which should be taken
                                 * as the default. */
  };

  unsigned int get_selector_infos (unsigned int                           start_offset,
                                   unsigned int                          *selectors_count, /* IN/OUT.  May be NULL. */
                                   hb_aat_layout_feature_selector_info_t *selectors,       /* OUT.     May be NULL. */
                                   unsigned int                          *pdefault_index,  /* OUT.     May be NULL. */
                                   const void *base) const
  {
    hb_array_t< const SettingName> settings_table = (base+settingTableZ).as_array (nSettings);

    static_assert (Index::NOT_FOUND_INDEX == HB_AAT_LAYOUT_NO_SELECTOR_INDEX, "");

    hb_aat_layout_feature_selector_t default_selector = HB_AAT_LAYOUT_FEATURE_SELECTOR_INVALID;
    unsigned int default_index = Index::NOT_FOUND_INDEX;
    if (featureFlags & Exclusive)
    {
      default_index = (featureFlags & NotDefault) ? featureFlags & IndexMask : 0;
      default_selector = settings_table[default_index].get_selector ();
    }
    if (pdefault_index)
      *pdefault_index = default_index;

    if (selectors_count)
    {
      hb_array_t<const SettingName> arr = settings_table.sub_array (start_offset, selectors_count);
      for (unsigned int i = 0; i < arr.length; i++)
        settings_table[start_offset + i].get_info (&selectors[i], default_selector);
    }
    return settings_table.length;
  }

  hb_aat_layout_feature_type_t get_feature_type () const
  { return (hb_aat_layout_feature_type_t) (unsigned int) feature; }

  hb_ot_name_id_t get_feature_name_id () const { return nameIndex; }

  bool sanitize (hb_sanitize_context_t *c, const void *base) const
  {
    TRACE_SANITIZE (this);
    return_trace (likely (c->check_struct (this) &&
                          (base+settingTableZ).sanitize (c, nSettings)));
  }

  protected:
  HBUINT16      feature;        /* Feature type. */
  HBUINT16      nSettings;      /* The number of records in the setting name array. */
  LOffsetTo<UnsizedArrayOf<SettingName>, false>
                settingTableZ;  /* Offset in bytes from the beginning of this table to
                                 * this feature's setting name array. The actual type of
                                 * record this offset refers to will depend on the
                                 * exclusivity value, as described below. */
  HBUINT16      featureFlags;   /* Single-bit flags associated with the feature type. */
  HBINT16       nameIndex;      /* The name table index for the feature's name.
                                 * This index has values greater than 255 and
                                 * less than 32768. */
  public:
  DEFINE_SIZE_STATIC (12);
};

struct feat
{
  static constexpr hb_tag_t tableTag = HB_AAT_TAG_feat;

  bool has_data () const { return version.to_int (); }

  unsigned int get_feature_types (unsigned int                  start_offset,
                                  unsigned int                 *count,
                                  hb_aat_layout_feature_type_t *features) const
  {
    unsigned int feature_count = featureNameCount;
    if (count && *count)
    {
      unsigned int len = MIN (feature_count - start_offset, *count);
      for (unsigned int i = 0; i < len; i++)
        features[i] = namesZ[i + start_offset].get_feature_type ();
      *count = len;
    }
    return featureNameCount;
  }

  const FeatureName& get_feature (hb_aat_layout_feature_type_t feature_type) const
  {
    return namesZ.bsearch (featureNameCount, feature_type);
  }

  hb_ot_name_id_t get_feature_name_id (hb_aat_layout_feature_type_t feature) const
  { return get_feature (feature).get_feature_name_id (); }

  unsigned int get_selector_infos (hb_aat_layout_feature_type_t           feature_type,
                                   unsigned int                           start_offset,
                                   unsigned int                          *selectors_count, /* IN/OUT.  May be NULL. */
                                   hb_aat_layout_feature_selector_info_t *selectors,       /* OUT.     May be NULL. */
                                   unsigned int                          *default_index    /* OUT.     May be NULL. */) const
  {
    return get_feature (feature_type).get_selector_infos (start_offset, selectors_count, selectors,
                                                          default_index, this);

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