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/*
* Copyright © 2024 Adobe, 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.
*
* Adobe Author(s): Skef Iterum
*/
#ifndef HB_DEPEND_DATA_HH
#define HB_DEPEND_DATA_HH
/* This file exists to break include cycles: hb-ot-layout-gsubgpos.hh needs
* hb_depend_data_builder_t for hb_depend_context_t, but hb-depend.hh pulls
* in table headers that include hb-ot-layout-gsubgpos.hh. */
#include "hb.hh"
#include "hb-multimap.hh"
/* hb_subset_depend_edge_flags_t is defined in hb-depend.h (public header).
* We redeclare it here under the same include-guard so internal code that
* includes hb-depend-data.hh without going through hb-depend.h still gets
* the type. The definitions must stay in sync. */
#ifndef HB_SUBSET_DEPEND_EDGE_FLAGS_T_DEFINED
#define HB_SUBSET_DEPEND_EDGE_FLAGS_T_DEFINED
typedef enum {
HB_SUBSET_DEPEND_EDGE_FLAG_NONE = 0x00u,
HB_SUBSET_DEPEND_EDGE_FLAG_FROM_CONTEXT_POSITION = 0x01u,
HB_SUBSET_DEPEND_EDGE_FLAG_FROM_NESTED_CONTEXT = 0x02u,
} hb_subset_depend_edge_flags_t;
#endif
/* Apply operator overloads now that hb.hh (and thus hb-algs.hh) is available. */
HB_MARK_AS_FLAG_T (hb_subset_depend_edge_flags_t);
/* High bit of a context-set element marks it as an index into the sets array
* rather than a raw glyph ID. */
#define HB_DEPEND_CONTEXT_SET_FLAG 0x80000000u
/**
* hb_depend_edge_t:
*
* Internal structure representing a single dependency edge in the graph.
* Records that glyph A depends on glyph B through a specific OpenType
* mechanism (table_tag), with additional metadata:
*
* - table_tag: Source table (GSUB, glyf, CFF, COLR, MATH)
* - dependent: Target glyph ID
* - layout_tag: Feature tag (for GSUB), else 0
* - ligature_set: Index into sets array for ligature components, else INVALID
* - context_set: Index into sets array for context requirements, else INVALID
* - flags: Edge flags (FROM_CONTEXT_POSITION, FROM_NESTED_CONTEXT)
*/
struct hb_depend_edge_t {
hb_depend_edge_t() = delete;
hb_depend_edge_t(hb_tag_t table_tag,
hb_codepoint_t dependent,
hb_tag_t layout_tag,
hb_codepoint_t ligature_set,
hb_codepoint_t context_set,
hb_subset_depend_edge_flags_t flags = HB_SUBSET_DEPEND_EDGE_FLAG_NONE) : table_tag(table_tag),
dependent(dependent), layout_tag(layout_tag),
ligature_set(ligature_set), context_set(context_set),
flags(flags)
{}
bool operator == (const hb_depend_edge_t &o) const
{
/* NOTE: flags intentionally excluded from equality comparison.
* Flags are metadata about how an edge was discovered (e.g.,
* FROM_CONTEXT_POSITION, FROM_NESTED_CONTEXT), not part of the
* edge's identity. Multiple discoveries of the same edge via
* different paths should be treated as duplicates. */
return table_tag == o.table_tag &&
dependent == o.dependent &&
layout_tag == o.layout_tag &&
ligature_set == o.ligature_set &&
context_set == o.context_set;
}
uint32_t hash () const
{
/* FNV-1a hash of all identity fields (excludes flags) */
uint32_t current = 0x84222325; /* FNV-1a offset basis */
current = current ^ hb_hash (table_tag);
current = current * 16777619; /* FNV-1a prime */
current = current ^ hb_hash (dependent);
current = current * 16777619;
current = current ^ hb_hash (layout_tag);
current = current * 16777619;
current = current ^ hb_hash (ligature_set);
current = current * 16777619;
current = current ^ hb_hash (context_set);
current = current * 16777619;
return current;
}
hb_tag_t table_tag;
hb_codepoint_t dependent;
hb_tag_t layout_tag;
hb_codepoint_t ligature_set;
hb_codepoint_t context_set;
hb_subset_depend_edge_flags_t flags;
};
/**
* hb_depend_edge_key_t:
*
* Key structure for edge deduplication. Combines source glyph with edge record.
* Uses the record's equality and hash operators for comparison.
*/
struct hb_depend_edge_key_t {
hb_codepoint_t source;
hb_depend_edge_t record;
hb_depend_edge_key_t () : source (0), record (0, 0, 0, HB_CODEPOINT_INVALID, HB_CODEPOINT_INVALID, HB_SUBSET_DEPEND_EDGE_FLAG_NONE) {}
hb_depend_edge_key_t (hb_codepoint_t source,
hb_tag_t table_tag,
hb_tag_t layout_tag,
hb_codepoint_t dependent,
hb_codepoint_t ligature_set,
hb_codepoint_t context_set)
: source (source),
record (table_tag, dependent, layout_tag, ligature_set, context_set, HB_SUBSET_DEPEND_EDGE_FLAG_NONE) {}
bool operator == (const hb_depend_edge_key_t &o) const
{
return source == o.source && record == o.record;
}
uint32_t hash () const
{
/* Combine source hash with record hash */
uint32_t current = 0x84222325; /* FNV-1a offset basis */
current = current ^ hb_hash (source);
current = current * 16777619; /* FNV-1a prime */
current = current ^ record.hash ();
current = current * 16777619;
return current;
}
};
/**
* hb_depend_glyph_record_t:
*
* Internal structure holding all dependency edges for a single glyph.
*/
struct hb_depend_glyph_record_t {
hb_vector_t<hb_depend_edge_t> dependencies;
};
/**
* hb_depend_lookup_revmap_t:
*
* Internal structure tracking which features are associated with a lookup.
* Used during GSUB dependency analysis to record the feature tags that
* activate each lookup.
*/
struct hb_depend_lookup_revmap_t
{
hb_depend_lookup_revmap_t () = default;
explicit hb_depend_lookup_revmap_t (bool full) : full (full) {}
hb_depend_lookup_revmap_t (const hb_depend_lookup_revmap_t &o) : full(o.full),
fv_indexes(o.fv_indexes) {}
hb_depend_lookup_revmap_t (hb_depend_lookup_revmap_t &&o) : full(o.full),
fv_indexes(std::move(o.fv_indexes)) {}
hb_depend_lookup_revmap_t& operator = (const hb_depend_lookup_revmap_t &o)
{
full = o.full;
fv_indexes = o.fv_indexes;
return *this;
}
bool full = true;
hb_set_t fv_indexes;
};
/**
* hb_depend_data_t:
*
* Persistent dependency graph data, retained for the lifetime of hb_subset_depend_t.
* Contains only what is needed at query time:
* - glyph_dependencies: Per-glyph edge lists
* - sets: Ligature and context sets indexed by set ID
*
* Constructed via hb_depend_data_builder_t; immutable thereafter.
*/
struct hb_depend_data_t
{
/* Set storage: vector of heap-allocated sets (both ligature and context sets).
* Using unique_ptr follows HarfBuzz pattern and provides stable pointers. */
hb_vector_t<hb::unique_ptr<hb_set_t>> sets;
hb_vector_t<hb_depend_glyph_record_t> glyph_dependencies;
const hb_set_t *get_set_from_index (hb_codepoint_t index)
{
if (index < sets.length)
return sets[index].get ();
return nullptr;
}
unsigned int get_glyph_entry_count (hb_codepoint_t gid) const
{
if (gid < glyph_dependencies.length)
return glyph_dependencies[gid].dependencies.length;
return 0;
}
bool get_glyph_entry (hb_codepoint_t gid, unsigned int index,
hb_tag_t *table_tag, hb_codepoint_t *dependent,
hb_tag_t *layout_tag, hb_codepoint_t *ligature_set,
hb_codepoint_t *context_set, uint8_t *flags)
{
if (gid < glyph_dependencies.length &&
index < glyph_dependencies[gid].dependencies.length) {
auto &d = glyph_dependencies[gid].dependencies[index];
*table_tag = d.table_tag;
*dependent = d.dependent;
*layout_tag = d.layout_tag;
*ligature_set = d.ligature_set;
*context_set = d.context_set;
if (flags) *flags = d.flags;
return true;
}
return false;
}
void print ()
{
for (unsigned i = 0; i < glyph_dependencies.length; i++) {
auto &gd = glyph_dependencies[i];
if (!gd.dependencies.length)
continue;
printf ("GID %u:\n", i);
for (auto &d : gd.dependencies) {
if (d.table_tag == HB_OT_TAG_GSUB) {
printf (" layout %c%c%c%c -> %u", HB_UNTAG(d.layout_tag), d.dependent);
if (d.ligature_set != HB_CODEPOINT_INVALID)
printf (" (ligature)");
} else {
printf (" %c%c%c%c -> %u", HB_UNTAG(d.table_tag), d.dependent);
}
printf ("\n");
}
}
}
};
/**
* hb_depend_data_builder_t:
*
* Temporary builder for constructing hb_depend_data_t. Holds all state
* needed during graph extraction; goes out of scope (and is freed) when
* construction is complete, leaving only hb_depend_data_t.
*
* Temporary state (freed on destruction):
* - lookup_features: Lookup index to feature tag mapping
* - seen_edges: Struct-based edge deduplication table
* - set_to_index: Content-based context set deduplication map
* - free_set_list: Indices of freed sets available for reuse
* - current_context_set_index: Context requirements for current rule
* - current_edge_flags: Flags to apply to edges being recorded
*/
struct hb_depend_data_builder_t
{
hb_depend_data_builder_t (hb_depend_data_t &data_)
: current_context_set_index (HB_CODEPOINT_INVALID),
current_edge_flags (HB_SUBSET_DEPEND_EDGE_FLAG_NONE),
data (data_) {}
/* Forward to data for use during construction (e.g. from hb_depend_context_t) */
const hb_set_t *get_set_from_index (hb_codepoint_t index)
{ return data.get_set_from_index (index); }
/* Free an unused ligature set for reuse.
* Only called for ligature sets that were allocated but had no edges added. */
void free_ligature_set (hb_codepoint_t set_index)
{
if (set_index >= data.sets.length)
{
DEBUG_MSG (SUBSET, nullptr, "Attempting to free invalid set %u (max is %u)",
set_index, data.sets.length - 1);
return;
}
data.sets[set_index]->clear ();
check_success (free_set_list.push_or_fail (set_index));
}
/* Allocate a new ligature set (no deduplication). */
hb_codepoint_t new_ligature_set (hb_codepoint_t cp)
{
hb_set_t temp_set;
temp_set.add (cp);
return new_ligature_set (temp_set);
}
hb_codepoint_t new_ligature_set (hb_set_t &set)
{
hb_codepoint_t set_index;
if (free_set_list.length > 0)
{
set_index = free_set_list.pop ();
data.sets[set_index]->set (set);
if (unlikely (data.sets[set_index]->in_error ()))
return fail_invalid ();
}
else
{
set_index = data.sets.length;
hb_set_t *new_set = hb_set_create ();
if (unlikely (!new_set))
return fail_invalid ();
new_set->set (set);
if (unlikely (new_set->in_error ()))
{
hb_set_destroy (new_set);
return fail_invalid ();
}
if (unlikely (!data.sets.push_or_fail (hb::unique_ptr<hb_set_t> {new_set})))
return fail_invalid ();
}
return set_index;
}
/* Find existing context set with same contents, or create new one (with deduplication).
* Uses content-based deduplication via hb_hashmap_t with pointer keys. */
hb_codepoint_t find_or_create_context_set (const hb_set_t &set)
{
hb_codepoint_t *existing_idx = nullptr;
if (set_to_index.has (&set, &existing_idx))
return *existing_idx;
hb_codepoint_t new_idx = new_ligature_set (const_cast<hb_set_t&>(set));
if (unlikely (new_idx == HB_CODEPOINT_INVALID))
return HB_CODEPOINT_INVALID;
if (unlikely (!set_to_index.set (data.sets[new_idx].get (), new_idx)))
return fail_invalid ();
return new_idx;
}
/* Build a context set from context information.
* Encodes backtrack and lookahead requirements as a flattened set.
* Returns HB_CODEPOINT_INVALID if no context.
*
* To ensure canonical encoding and avoid redundancy:
* 1. First pass: collect all direct (single-glyph) requirements
* 2. Second pass: create disjunction sets, subtracting direct requirements
* 3. Combine: add direct requirements and filtered disjunction references
*/
hb_codepoint_t build_context_set (const hb_vector_t<hb_set_t> *backtrack_sets,
const hb_vector_t<hb_set_t> *lookahead_sets)
{
if ((!backtrack_sets || backtrack_sets->length == 0) &&
(!lookahead_sets || lookahead_sets->length == 0))
return HB_CODEPOINT_INVALID;
/* First pass: collect all direct (single-glyph) requirements */
hb_set_t direct_requirements;
if (backtrack_sets)
{
for (const auto &back_set : *backtrack_sets)
{
if (back_set.get_population () == 1)
direct_requirements.add (back_set.get_min ());
}
}
if (lookahead_sets)
{
for (const auto &look_set : *lookahead_sets)
{
if (look_set.get_population () == 1)
direct_requirements.add (look_set.get_min ());
}
}
/* Second pass: create disjunction sets, filtering out direct requirements */
hb_set_t context_elements;
if (backtrack_sets)
{
for (const auto &back_set : *backtrack_sets)
{
if (back_set.get_population () > 1)
{
hb_set_t filtered_set;
filtered_set.set (back_set);
filtered_set.subtract (direct_requirements);
if (unlikely (filtered_set.in_error ()))
return fail_invalid ();
if (!filtered_set.is_empty ())
{
hb_codepoint_t set_idx = find_or_create_context_set (filtered_set);
if (unlikely (set_idx == HB_CODEPOINT_INVALID))
return HB_CODEPOINT_INVALID;
context_elements.add (HB_DEPEND_CONTEXT_SET_FLAG | set_idx);
}
}
}
}
if (lookahead_sets)
{
for (const auto &look_set : *lookahead_sets)
{
if (look_set.get_population () > 1)
{
hb_set_t filtered_set;
filtered_set.set (look_set);
filtered_set.subtract (direct_requirements);
if (unlikely (filtered_set.in_error ()))
return fail_invalid ();
if (!filtered_set.is_empty ())
{
hb_codepoint_t set_idx = find_or_create_context_set (filtered_set);
if (unlikely (set_idx == HB_CODEPOINT_INVALID))
return HB_CODEPOINT_INVALID;
context_elements.add (HB_DEPEND_CONTEXT_SET_FLAG | set_idx);
}
}
}
}
context_elements.union_ (direct_requirements);
if (unlikely (direct_requirements.in_error () ||
context_elements.in_error ()))
return fail_invalid ();
if (context_elements.is_empty ())
return HB_CODEPOINT_INVALID;
return find_or_create_context_set (context_elements);
}
bool add_depend_layout (hb_codepoint_t target, hb_tag_t table_tag,
hb_tag_t layout_tag,
hb_codepoint_t dependent,
hb_codepoint_t lig_set = HB_CODEPOINT_INVALID,
hb_codepoint_t context_set = HB_CODEPOINT_INVALID,
hb_subset_depend_edge_flags_t flags = HB_SUBSET_DEPEND_EDGE_FLAG_NONE)
{
if (target >= data.glyph_dependencies.length) {
DEBUG_MSG (SUBSET, nullptr, "Dependency glyph %u for %c%c%c%c too large",
target, HB_UNTAG(table_tag));
return false;
}
hb_depend_edge_key_t key (target, table_tag, layout_tag, dependent, lig_set, context_set);
if (seen_edges.has (key))
return false;
if (unlikely (!seen_edges.set (key, true)))
return fail ();
auto &gdr = data.glyph_dependencies[target];
if (unlikely (!gdr.dependencies.push_or_fail (table_tag, dependent, layout_tag,
lig_set, context_set, flags)))
return fail ();
return true;
}
bool add_gsub_lookup (hb_codepoint_t target, hb_codepoint_t lookup_index,
hb_codepoint_t dependent,
hb_codepoint_t lig_set = HB_CODEPOINT_INVALID,
hb_codepoint_t context_set = HB_CODEPOINT_INVALID)
{
if (context_set == HB_CODEPOINT_INVALID)
context_set = current_context_set_index;
hb_subset_depend_edge_flags_t flags = current_edge_flags;
bool any_added = false;
for (auto t : lookup_features[lookup_index]) {
if (add_depend_layout (target, HB_OT_TAG_GSUB, t, dependent, lig_set, context_set, flags))
any_added = true;
}
return any_added;
}
void add_depend (hb_codepoint_t target, hb_tag_t table_tag,
hb_codepoint_t dependent,
hb_codepoint_t lig_set = HB_CODEPOINT_INVALID,
hb_codepoint_t context_set = HB_CODEPOINT_INVALID,
hb_subset_depend_edge_flags_t flags = HB_SUBSET_DEPEND_EDGE_FLAG_NONE)
{
add_depend_layout (target, table_tag, HB_CODEPOINT_INVALID, dependent, lig_set,
context_set, flags);
}
hb_codepoint_t get_nominal_glyph (hb_codepoint_t cp)
{ return hb_map_get (&nominal_glyphs, cp); }
HB_INTERNAL bool compile (hb_face_t *face);
bool fail () { successful = false; return false; }
hb_codepoint_t fail_invalid () { fail (); return HB_CODEPOINT_INVALID; }
bool check_success (bool s) { successful = (successful && s); return successful; }
HB_INTERNAL void get_gsub_dependencies (hb_face_t *face);
bool successful = true;
hb_set_t unicodes;
hb_map_t nominal_glyphs;
hb_vector_t<hb_set_t> lookup_features;
hb_hashmap_t<hb_depend_edge_key_t, bool> seen_edges;
hb_hashmap_t<const hb_set_t*, hb_codepoint_t> set_to_index;
hb_vector_t<hb_codepoint_t> free_set_list;
hb_codepoint_t current_context_set_index;
hb_subset_depend_edge_flags_t current_edge_flags;
hb_depend_data_t &data;
};
#endif /* HB_DEPEND_DATA_HH */