[repacker] Begin splitting up the repacker implementation into several files.
diff --git a/src/graph/graph.hh b/src/graph/graph.hh
new file mode 100644
index 0000000..28d69c9
--- /dev/null
+++ b/src/graph/graph.hh
@@ -0,0 +1,965 @@
+/*
+ * Copyright © 2022 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): Garret Rieger
+ */
+
+#ifndef GRAPH_GRAPH_HH
+#define GRAPH_GRAPH_HH
+
+namespace graph {
+
+struct graph_t
+{
+ struct vertex_t
+ {
+ hb_serialize_context_t::object_t obj;
+ int64_t distance = 0 ;
+ int64_t space = 0 ;
+ hb_vector_t<unsigned> parents;
+ unsigned start = 0;
+ unsigned end = 0;
+ unsigned priority = 0;
+
+ friend void swap (vertex_t& a, vertex_t& b)
+ {
+ hb_swap (a.obj, b.obj);
+ hb_swap (a.distance, b.distance);
+ hb_swap (a.space, b.space);
+ hb_swap (a.parents, b.parents);
+ hb_swap (a.start, b.start);
+ hb_swap (a.end, b.end);
+ hb_swap (a.priority, b.priority);
+ }
+
+ bool is_shared () const
+ {
+ return parents.length > 1;
+ }
+
+ unsigned incoming_edges () const
+ {
+ return parents.length;
+ }
+
+ void remove_parent (unsigned parent_index)
+ {
+ for (unsigned i = 0; i < parents.length; i++)
+ {
+ if (parents[i] != parent_index) continue;
+ parents.remove (i);
+ break;
+ }
+ }
+
+ void remap_parents (const hb_vector_t<unsigned>& id_map)
+ {
+ for (unsigned i = 0; i < parents.length; i++)
+ parents[i] = id_map[parents[i]];
+ }
+
+ void remap_parent (unsigned old_index, unsigned new_index)
+ {
+ for (unsigned i = 0; i < parents.length; i++)
+ {
+ if (parents[i] == old_index)
+ parents[i] = new_index;
+ }
+ }
+
+ bool is_leaf () const
+ {
+ return !obj.real_links.length && !obj.virtual_links.length;
+ }
+
+ bool raise_priority ()
+ {
+ if (has_max_priority ()) return false;
+ priority++;
+ return true;
+ }
+
+ bool has_max_priority () const {
+ return priority >= 3;
+ }
+
+ int64_t modified_distance (unsigned order) const
+ {
+ // TODO(garretrieger): once priority is high enough, should try
+ // setting distance = 0 which will force to sort immediately after
+ // it's parent where possible.
+
+ int64_t modified_distance =
+ hb_min (hb_max(distance + distance_modifier (), 0), 0x7FFFFFFFFFF);
+ if (has_max_priority ()) {
+ modified_distance = 0;
+ }
+ return (modified_distance << 18) | (0x003FFFF & order);
+ }
+
+ int64_t distance_modifier () const
+ {
+ if (!priority) return 0;
+ int64_t table_size = obj.tail - obj.head;
+
+ if (priority == 1)
+ return -table_size / 2;
+
+ return -table_size;
+ }
+ };
+
+ struct overflow_record_t
+ {
+ unsigned parent;
+ unsigned child;
+ };
+
+ /*
+ * A topological sorting of an object graph. Ordered
+ * in reverse serialization order (first object in the
+ * serialization is at the end of the list). This matches
+ * the 'packed' object stack used internally in the
+ * serializer
+ */
+ template<typename T>
+ graph_t (const T& objects)
+ : parents_invalid (true),
+ distance_invalid (true),
+ positions_invalid (true),
+ successful (true)
+ {
+ num_roots_for_space_.push (1);
+ bool removed_nil = false;
+ vertices_.alloc (objects.length);
+ vertices_scratch_.alloc (objects.length);
+ for (unsigned i = 0; i < objects.length; i++)
+ {
+ // TODO(grieger): check all links point to valid objects.
+
+ // If this graph came from a serialization buffer object 0 is the
+ // nil object. We don't need it for our purposes here so drop it.
+ if (i == 0 && !objects[i])
+ {
+ removed_nil = true;
+ continue;
+ }
+
+ vertex_t* v = vertices_.push ();
+ if (check_success (!vertices_.in_error ()))
+ v->obj = *objects[i];
+ if (!removed_nil) continue;
+ // Fix indices to account for removed nil object.
+ for (auto& l : v->obj.all_links_writer ()) {
+ l.objidx--;
+ }
+ }
+ }
+
+ ~graph_t ()
+ {
+ vertices_.fini ();
+ }
+
+ bool in_error () const
+ {
+ return !successful ||
+ vertices_.in_error () ||
+ num_roots_for_space_.in_error ();
+ }
+
+ const vertex_t& root () const
+ {
+ return vertices_[root_idx ()];
+ }
+
+ unsigned root_idx () const
+ {
+ // Object graphs are in reverse order, the first object is at the end
+ // of the vector. Since the graph is topologically sorted it's safe to
+ // assume the first object has no incoming edges.
+ return vertices_.length - 1;
+ }
+
+ const hb_serialize_context_t::object_t& object(unsigned i) const
+ {
+ return vertices_[i].obj;
+ }
+
+ /*
+ * Generates a new topological sorting of graph ordered by the shortest
+ * distance to each node.
+ */
+ void sort_shortest_distance ()
+ {
+ positions_invalid = true;
+
+ if (vertices_.length <= 1) {
+ // Graph of 1 or less doesn't need sorting.
+ return;
+ }
+
+ update_distances ();
+
+ hb_priority_queue_t queue;
+ hb_vector_t<vertex_t> &sorted_graph = vertices_scratch_;
+ if (unlikely (!check_success (sorted_graph.resize (vertices_.length)))) return;
+ hb_vector_t<unsigned> id_map;
+ if (unlikely (!check_success (id_map.resize (vertices_.length)))) return;
+
+ hb_vector_t<unsigned> removed_edges;
+ if (unlikely (!check_success (removed_edges.resize (vertices_.length)))) return;
+ update_parents ();
+
+ queue.insert (root ().modified_distance (0), root_idx ());
+ int new_id = root_idx ();
+ unsigned order = 1;
+ while (!queue.in_error () && !queue.is_empty ())
+ {
+ unsigned next_id = queue.pop_minimum().second;
+
+ hb_swap (sorted_graph[new_id], vertices_[next_id]);
+ const vertex_t& next = sorted_graph[new_id];
+
+ id_map[next_id] = new_id--;
+
+ for (const auto& link : next.obj.all_links ()) {
+ removed_edges[link.objidx]++;
+ if (!(vertices_[link.objidx].incoming_edges () - removed_edges[link.objidx]))
+ // Add the order that the links were encountered to the priority.
+ // This ensures that ties between priorities objects are broken in a consistent
+ // way. More specifically this is set up so that if a set of objects have the same
+ // distance they'll be added to the topological order in the order that they are
+ // referenced from the parent object.
+ queue.insert (vertices_[link.objidx].modified_distance (order++),
+ link.objidx);
+ }
+ }
+
+ check_success (!queue.in_error ());
+ check_success (!sorted_graph.in_error ());
+ if (!check_success (new_id == -1))
+ print_orphaned_nodes ();
+
+ remap_all_obj_indices (id_map, &sorted_graph);
+
+ hb_swap (vertices_, sorted_graph);
+ }
+
+ /*
+ * Assign unique space numbers to each connected subgraph of 32 bit offset(s).
+ */
+ bool assign_32bit_spaces ()
+ {
+ unsigned root_index = root_idx ();
+ hb_set_t visited;
+ hb_set_t roots;
+ for (unsigned i = 0; i <= root_index; i++)
+ {
+ // Only real links can form 32 bit spaces
+ for (auto& l : vertices_[i].obj.real_links)
+ {
+ if (l.width == 4 && !l.is_signed)
+ {
+ roots.add (l.objidx);
+ find_subgraph (l.objidx, visited);
+ }
+ }
+ }
+
+ // Mark everything not in the subgraphs of 32 bit roots as visited.
+ // This prevents 32 bit subgraphs from being connected via nodes not in the 32 bit subgraphs.
+ visited.invert ();
+
+ if (!roots) return false;
+
+ while (roots)
+ {
+ unsigned next = HB_SET_VALUE_INVALID;
+ if (unlikely (!check_success (!roots.in_error ()))) break;
+ if (!roots.next (&next)) break;
+
+ hb_set_t connected_roots;
+ find_connected_nodes (next, roots, visited, connected_roots);
+ if (unlikely (!check_success (!connected_roots.in_error ()))) break;
+
+ isolate_subgraph (connected_roots);
+ if (unlikely (!check_success (!connected_roots.in_error ()))) break;
+
+ unsigned next_space = this->next_space ();
+ num_roots_for_space_.push (0);
+ for (unsigned root : connected_roots)
+ {
+ DEBUG_MSG (SUBSET_REPACK, nullptr, "Subgraph %u gets space %u", root, next_space);
+ vertices_[root].space = next_space;
+ num_roots_for_space_[next_space] = num_roots_for_space_[next_space] + 1;
+ distance_invalid = true;
+ positions_invalid = true;
+ }
+
+ // TODO(grieger): special case for GSUB/GPOS use extension promotions to move 16 bit space
+ // into the 32 bit space as needed, instead of using isolation.
+ }
+
+
+
+ return true;
+ }
+
+ /*
+ * Isolates the subgraph of nodes reachable from root. Any links to nodes in the subgraph
+ * that originate from outside of the subgraph will be removed by duplicating the linked to
+ * object.
+ *
+ * Indices stored in roots will be updated if any of the roots are duplicated to new indices.
+ */
+ bool isolate_subgraph (hb_set_t& roots)
+ {
+ update_parents ();
+ hb_map_t subgraph;
+
+ // incoming edges to root_idx should be all 32 bit in length so we don't need to de-dup these
+ // set the subgraph incoming edge count to match all of root_idx's incoming edges
+ hb_set_t parents;
+ for (unsigned root_idx : roots)
+ {
+ subgraph.set (root_idx, wide_parents (root_idx, parents));
+ find_subgraph (root_idx, subgraph);
+ }
+
+ unsigned original_root_idx = root_idx ();
+ hb_map_t index_map;
+ bool made_changes = false;
+ for (auto entry : subgraph.iter ())
+ {
+ const auto& node = vertices_[entry.first];
+ unsigned subgraph_incoming_edges = entry.second;
+
+ if (subgraph_incoming_edges < node.incoming_edges ())
+ {
+ // Only de-dup objects with incoming links from outside the subgraph.
+ made_changes = true;
+ duplicate_subgraph (entry.first, index_map);
+ }
+ }
+
+ if (!made_changes)
+ return false;
+
+ if (original_root_idx != root_idx ()
+ && parents.has (original_root_idx))
+ {
+ // If the root idx has changed since parents was determined, update root idx in parents
+ parents.add (root_idx ());
+ parents.del (original_root_idx);
+ }
+
+ auto new_subgraph =
+ + subgraph.keys ()
+ | hb_map([&] (unsigned node_idx) {
+ const unsigned *v;
+ if (index_map.has (node_idx, &v)) return *v;
+ return node_idx;
+ })
+ ;
+
+ remap_obj_indices (index_map, new_subgraph);
+ remap_obj_indices (index_map, parents.iter (), true);
+
+ // Update roots set with new indices as needed.
+ unsigned next = HB_SET_VALUE_INVALID;
+ while (roots.next (&next))
+ {
+ const unsigned *v;
+ if (index_map.has (next, &v))
+ {
+ roots.del (next);
+ roots.add (*v);
+ }
+ }
+
+ return true;
+ }
+
+ void find_subgraph (unsigned node_idx, hb_map_t& subgraph)
+ {
+ for (const auto& link : vertices_[node_idx].obj.all_links ())
+ {
+ const unsigned *v;
+ if (subgraph.has (link.objidx, &v))
+ {
+ subgraph.set (link.objidx, *v + 1);
+ continue;
+ }
+ subgraph.set (link.objidx, 1);
+ find_subgraph (link.objidx, subgraph);
+ }
+ }
+
+ void find_subgraph (unsigned node_idx, hb_set_t& subgraph)
+ {
+ if (subgraph.has (node_idx)) return;
+ subgraph.add (node_idx);
+ for (const auto& link : vertices_[node_idx].obj.all_links ())
+ find_subgraph (link.objidx, subgraph);
+ }
+
+ /*
+ * duplicates all nodes in the subgraph reachable from node_idx. Does not re-assign
+ * links. index_map is updated with mappings from old id to new id. If a duplication has already
+ * been performed for a given index, then it will be skipped.
+ */
+ void duplicate_subgraph (unsigned node_idx, hb_map_t& index_map)
+ {
+ if (index_map.has (node_idx))
+ return;
+
+ index_map.set (node_idx, duplicate (node_idx));
+ for (const auto& l : object (node_idx).all_links ()) {
+ duplicate_subgraph (l.objidx, index_map);
+ }
+ }
+
+ /*
+ * Creates a copy of node_idx and returns it's new index.
+ */
+ unsigned duplicate (unsigned node_idx)
+ {
+ positions_invalid = true;
+ distance_invalid = true;
+
+ auto* clone = vertices_.push ();
+ auto& child = vertices_[node_idx];
+ if (vertices_.in_error ()) {
+ return -1;
+ }
+
+ clone->obj.head = child.obj.head;
+ clone->obj.tail = child.obj.tail;
+ clone->distance = child.distance;
+ clone->space = child.space;
+ clone->parents.reset ();
+
+ unsigned clone_idx = vertices_.length - 2;
+ for (const auto& l : child.obj.real_links)
+ {
+ clone->obj.real_links.push (l);
+ vertices_[l.objidx].parents.push (clone_idx);
+ }
+ for (const auto& l : child.obj.virtual_links)
+ {
+ clone->obj.virtual_links.push (l);
+ vertices_[l.objidx].parents.push (clone_idx);
+ }
+
+ check_success (!clone->obj.real_links.in_error ());
+ check_success (!clone->obj.virtual_links.in_error ());
+
+ // The last object is the root of the graph, so swap back the root to the end.
+ // The root's obj idx does change, however since it's root nothing else refers to it.
+ // all other obj idx's will be unaffected.
+ hb_swap (vertices_[vertices_.length - 2], *clone);
+
+ // Since the root moved, update the parents arrays of all children on the root.
+ for (const auto& l : root ().obj.all_links ())
+ vertices_[l.objidx].remap_parent (root_idx () - 1, root_idx ());
+
+ return clone_idx;
+ }
+
+ /*
+ * Creates a copy of child and re-assigns the link from
+ * parent to the clone. The copy is a shallow copy, objects
+ * linked from child are not duplicated.
+ */
+ bool duplicate (unsigned parent_idx, unsigned child_idx)
+ {
+ update_parents ();
+
+ unsigned links_to_child = 0;
+ for (const auto& l : vertices_[parent_idx].obj.all_links ())
+ {
+ if (l.objidx == child_idx) links_to_child++;
+ }
+
+ if (vertices_[child_idx].incoming_edges () <= links_to_child)
+ {
+ // Can't duplicate this node, doing so would orphan the original one as all remaining links
+ // to child are from parent.
+ DEBUG_MSG (SUBSET_REPACK, nullptr, " Not duplicating %d => %d",
+ parent_idx, child_idx);
+ return false;
+ }
+
+ DEBUG_MSG (SUBSET_REPACK, nullptr, " Duplicating %d => %d",
+ parent_idx, child_idx);
+
+ unsigned clone_idx = duplicate (child_idx);
+ if (clone_idx == (unsigned) -1) return false;
+ // duplicate shifts the root node idx, so if parent_idx was root update it.
+ if (parent_idx == clone_idx) parent_idx++;
+
+ auto& parent = vertices_[parent_idx];
+ for (auto& l : parent.obj.all_links_writer ())
+ {
+ if (l.objidx != child_idx)
+ continue;
+
+ reassign_link (l, parent_idx, clone_idx);
+ }
+
+ return true;
+ }
+
+ /*
+ * Raises the sorting priority of all children.
+ */
+ bool raise_childrens_priority (unsigned parent_idx)
+ {
+ DEBUG_MSG (SUBSET_REPACK, nullptr, " Raising priority of all children of %d",
+ parent_idx);
+ // This operation doesn't change ordering until a sort is run, so no need
+ // to invalidate positions. It does not change graph structure so no need
+ // to update distances or edge counts.
+ auto& parent = vertices_[parent_idx].obj;
+ bool made_change = false;
+ for (auto& l : parent.all_links_writer ())
+ made_change |= vertices_[l.objidx].raise_priority ();
+ return made_change;
+ }
+
+ /*
+ * Will any offsets overflow on graph when it's serialized?
+ */
+ bool will_overflow (hb_vector_t<overflow_record_t>* overflows = nullptr)
+ {
+ if (overflows) overflows->resize (0);
+ update_positions ();
+
+ for (int parent_idx = vertices_.length - 1; parent_idx >= 0; parent_idx--)
+ {
+ // Don't need to check virtual links for overflow
+ for (const auto& link : vertices_[parent_idx].obj.real_links)
+ {
+ int64_t offset = compute_offset (parent_idx, link);
+ if (is_valid_offset (offset, link))
+ continue;
+
+ if (!overflows) return true;
+
+ overflow_record_t r;
+ r.parent = parent_idx;
+ r.child = link.objidx;
+ overflows->push (r);
+ }
+ }
+
+ if (!overflows) return false;
+ return overflows->length;
+ }
+
+ void print_orphaned_nodes ()
+ {
+ if (!DEBUG_ENABLED(SUBSET_REPACK)) return;
+
+ DEBUG_MSG (SUBSET_REPACK, nullptr, "Graph is not fully connected.");
+ parents_invalid = true;
+ update_parents();
+
+ for (unsigned i = 0; i < root_idx (); i++)
+ {
+ const auto& v = vertices_[i];
+ if (!v.parents)
+ DEBUG_MSG (SUBSET_REPACK, nullptr, "Node %u is orphaned.", i);
+ }
+ }
+
+ void print_overflows (const hb_vector_t<overflow_record_t>& overflows)
+ {
+ if (!DEBUG_ENABLED(SUBSET_REPACK)) return;
+
+ update_parents ();
+ int limit = 10;
+ for (const auto& o : overflows)
+ {
+ if (!limit--) break;
+ const auto& parent = vertices_[o.parent];
+ const auto& child = vertices_[o.child];
+ DEBUG_MSG (SUBSET_REPACK, nullptr,
+ " overflow from "
+ "%4d (%4d in, %4d out, space %2d) => "
+ "%4d (%4d in, %4d out, space %2d)",
+ o.parent,
+ parent.incoming_edges (),
+ parent.obj.real_links.length + parent.obj.virtual_links.length,
+ space_for (o.parent),
+ o.child,
+ child.incoming_edges (),
+ child.obj.real_links.length + child.obj.virtual_links.length,
+ space_for (o.child));
+ }
+ if (overflows.length > 10) {
+ DEBUG_MSG (SUBSET_REPACK, nullptr, " ... plus %d more overflows.", overflows.length - 10);
+ }
+ }
+
+ unsigned num_roots_for_space (unsigned space) const
+ {
+ return num_roots_for_space_[space];
+ }
+
+ unsigned next_space () const
+ {
+ return num_roots_for_space_.length;
+ }
+
+ void move_to_new_space (const hb_set_t& indices)
+ {
+ num_roots_for_space_.push (0);
+ unsigned new_space = num_roots_for_space_.length - 1;
+
+ for (unsigned index : indices) {
+ auto& node = vertices_[index];
+ num_roots_for_space_[node.space] = num_roots_for_space_[node.space] - 1;
+ num_roots_for_space_[new_space] = num_roots_for_space_[new_space] + 1;
+ node.space = new_space;
+ distance_invalid = true;
+ positions_invalid = true;
+ }
+ }
+
+ unsigned space_for (unsigned index, unsigned* root = nullptr) const
+ {
+ const auto& node = vertices_[index];
+ if (node.space)
+ {
+ if (root != nullptr)
+ *root = index;
+ return node.space;
+ }
+
+ if (!node.parents)
+ {
+ if (root)
+ *root = index;
+ return 0;
+ }
+
+ return space_for (node.parents[0], root);
+ }
+
+ void err_other_error () { this->successful = false; }
+
+ size_t total_size_in_bytes () const {
+ size_t total_size = 0;
+ for (unsigned i = 0; i < vertices_.length; i++) {
+ size_t size = vertices_[i].obj.tail - vertices_[i].obj.head;
+ total_size += size;
+ }
+ return total_size;
+ }
+
+
+ private:
+
+ /*
+ * Returns the numbers of incoming edges that are 32bits wide.
+ */
+ unsigned wide_parents (unsigned node_idx, hb_set_t& parents) const
+ {
+ unsigned count = 0;
+ hb_set_t visited;
+ for (unsigned p : vertices_[node_idx].parents)
+ {
+ if (visited.has (p)) continue;
+ visited.add (p);
+
+ // Only real links can be wide
+ for (const auto& l : vertices_[p].obj.real_links)
+ {
+ if (l.objidx == node_idx && l.width == 4 && !l.is_signed)
+ {
+ count++;
+ parents.add (p);
+ }
+ }
+ }
+ return count;
+ }
+
+ bool check_success (bool success)
+ { return this->successful && (success || ((void) err_other_error (), false)); }
+
+ /*
+ * Creates a map from objid to # of incoming edges.
+ */
+ void update_parents ()
+ {
+ if (!parents_invalid) return;
+
+ for (unsigned i = 0; i < vertices_.length; i++)
+ vertices_[i].parents.reset ();
+
+ for (unsigned p = 0; p < vertices_.length; p++)
+ {
+ for (auto& l : vertices_[p].obj.all_links ())
+ {
+ vertices_[l.objidx].parents.push (p);
+ }
+ }
+
+ parents_invalid = false;
+ }
+
+ /*
+ * compute the serialized start and end positions for each vertex.
+ */
+ void update_positions ()
+ {
+ if (!positions_invalid) return;
+
+ unsigned current_pos = 0;
+ for (int i = root_idx (); i >= 0; i--)
+ {
+ auto& v = vertices_[i];
+ v.start = current_pos;
+ current_pos += v.obj.tail - v.obj.head;
+ v.end = current_pos;
+ }
+
+ positions_invalid = false;
+ }
+
+ /*
+ * Finds the distance to each object in the graph
+ * from the initial node.
+ */
+ void update_distances ()
+ {
+ if (!distance_invalid) return;
+
+ // Uses Dijkstra's algorithm to find all of the shortest distances.
+ // https://en.wikipedia.org/wiki/Dijkstra%27s_algorithm
+ //
+ // Implementation Note:
+ // Since our priority queue doesn't support fast priority decreases
+ // we instead just add new entries into the queue when a priority changes.
+ // Redundant ones are filtered out later on by the visited set.
+ // According to https://www3.cs.stonybrook.edu/~rezaul/papers/TR-07-54.pdf
+ // for practical performance this is faster then using a more advanced queue
+ // (such as a fibonacci queue) with a fast decrease priority.
+ for (unsigned i = 0; i < vertices_.length; i++)
+ {
+ if (i == vertices_.length - 1)
+ vertices_[i].distance = 0;
+ else
+ vertices_[i].distance = hb_int_max (int64_t);
+ }
+
+ hb_priority_queue_t queue;
+ queue.insert (0, vertices_.length - 1);
+
+ hb_vector_t<bool> visited;
+ visited.resize (vertices_.length);
+
+ while (!queue.in_error () && !queue.is_empty ())
+ {
+ unsigned next_idx = queue.pop_minimum ().second;
+ if (visited[next_idx]) continue;
+ const auto& next = vertices_[next_idx];
+ int64_t next_distance = vertices_[next_idx].distance;
+ visited[next_idx] = true;
+
+ for (const auto& link : next.obj.all_links ())
+ {
+ if (visited[link.objidx]) continue;
+
+ const auto& child = vertices_[link.objidx].obj;
+ unsigned link_width = link.width ? link.width : 4; // treat virtual offsets as 32 bits wide
+ int64_t child_weight = (child.tail - child.head) +
+ ((int64_t) 1 << (link_width * 8)) * (vertices_[link.objidx].space + 1);
+ int64_t child_distance = next_distance + child_weight;
+
+ if (child_distance < vertices_[link.objidx].distance)
+ {
+ vertices_[link.objidx].distance = child_distance;
+ queue.insert (child_distance, link.objidx);
+ }
+ }
+ }
+
+ check_success (!queue.in_error ());
+ if (!check_success (queue.is_empty ()))
+ {
+ print_orphaned_nodes ();
+ return;
+ }
+
+ distance_invalid = false;
+ }
+
+ int64_t compute_offset (
+ unsigned parent_idx,
+ const hb_serialize_context_t::object_t::link_t& link) const
+ {
+ const auto& parent = vertices_[parent_idx];
+ const auto& child = vertices_[link.objidx];
+ int64_t offset = 0;
+ switch ((hb_serialize_context_t::whence_t) link.whence) {
+ case hb_serialize_context_t::whence_t::Head:
+ offset = child.start - parent.start; break;
+ case hb_serialize_context_t::whence_t::Tail:
+ offset = child.start - parent.end; break;
+ case hb_serialize_context_t::whence_t::Absolute:
+ offset = child.start; break;
+ }
+
+ assert (offset >= link.bias);
+ offset -= link.bias;
+ return offset;
+ }
+
+ bool is_valid_offset (int64_t offset,
+ const hb_serialize_context_t::object_t::link_t& link) const
+ {
+ if (unlikely (!link.width))
+ // Virtual links can't overflow.
+ return link.is_signed || offset >= 0;
+
+ if (link.is_signed)
+ {
+ if (link.width == 4)
+ return offset >= -((int64_t) 1 << 31) && offset < ((int64_t) 1 << 31);
+ else
+ return offset >= -(1 << 15) && offset < (1 << 15);
+ }
+ else
+ {
+ if (link.width == 4)
+ return offset >= 0 && offset < ((int64_t) 1 << 32);
+ else if (link.width == 3)
+ return offset >= 0 && offset < ((int32_t) 1 << 24);
+ else
+ return offset >= 0 && offset < (1 << 16);
+ }
+ }
+
+ /*
+ * Updates a link in the graph to point to a different object. Corrects the
+ * parents vector on the previous and new child nodes.
+ */
+ void reassign_link (hb_serialize_context_t::object_t::link_t& link,
+ unsigned parent_idx,
+ unsigned new_idx)
+ {
+ unsigned old_idx = link.objidx;
+ link.objidx = new_idx;
+ vertices_[old_idx].remove_parent (parent_idx);
+ vertices_[new_idx].parents.push (parent_idx);
+ }
+
+ /*
+ * Updates all objidx's in all links using the provided mapping. Corrects incoming edge counts.
+ */
+ template<typename Iterator, hb_requires (hb_is_iterator (Iterator))>
+ void remap_obj_indices (const hb_map_t& id_map,
+ Iterator subgraph,
+ bool only_wide = false)
+ {
+ if (!id_map) return;
+ for (unsigned i : subgraph)
+ {
+ for (auto& link : vertices_[i].obj.all_links_writer ())
+ {
+ const unsigned *v;
+ if (!id_map.has (link.objidx, &v)) continue;
+ if (only_wide && !(link.width == 4 && !link.is_signed)) continue;
+
+ reassign_link (link, i, *v);
+ }
+ }
+ }
+
+ /*
+ * Updates all objidx's in all links using the provided mapping.
+ */
+ void remap_all_obj_indices (const hb_vector_t<unsigned>& id_map,
+ hb_vector_t<vertex_t>* sorted_graph) const
+ {
+ for (unsigned i = 0; i < sorted_graph->length; i++)
+ {
+ (*sorted_graph)[i].remap_parents (id_map);
+ for (auto& link : (*sorted_graph)[i].obj.all_links_writer ())
+ {
+ link.objidx = id_map[link.objidx];
+ }
+ }
+ }
+
+ /*
+ * Finds all nodes in targets that are reachable from start_idx, nodes in visited will be skipped.
+ * For this search the graph is treated as being undirected.
+ *
+ * Connected targets will be added to connected and removed from targets. All visited nodes
+ * will be added to visited.
+ */
+ void find_connected_nodes (unsigned start_idx,
+ hb_set_t& targets,
+ hb_set_t& visited,
+ hb_set_t& connected)
+ {
+ if (unlikely (!check_success (!visited.in_error ()))) return;
+ if (visited.has (start_idx)) return;
+ visited.add (start_idx);
+
+ if (targets.has (start_idx))
+ {
+ targets.del (start_idx);
+ connected.add (start_idx);
+ }
+
+ const auto& v = vertices_[start_idx];
+
+ // Graph is treated as undirected so search children and parents of start_idx
+ for (const auto& l : v.obj.all_links ())
+ find_connected_nodes (l.objidx, targets, visited, connected);
+
+ for (unsigned p : v.parents)
+ find_connected_nodes (p, targets, visited, connected);
+ }
+
+ public:
+ // TODO(garretrieger): make private, will need to move most of offset overflow code into graph.
+ hb_vector_t<vertex_t> vertices_;
+ hb_vector_t<vertex_t> vertices_scratch_;
+ private:
+ bool parents_invalid;
+ bool distance_invalid;
+ bool positions_invalid;
+ bool successful;
+ hb_vector_t<unsigned> num_roots_for_space_;
+};
+
+}
+
+#endif // GRAPH_GRAPH_HH
