| /* |
| * 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 |
| */ |
| |
| #include "hb-set.hh" |
| #include "hb-priority-queue.hh" |
| #include "hb-serialize.hh" |
| |
| #ifndef GRAPH_GRAPH_HH |
| #define GRAPH_GRAPH_HH |
| |
| namespace graph { |
| |
| /** |
| * Represents a serialized table in the form of a graph. |
| * Provides methods for modifying and reordering the 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; |
| } |
| |
| size_t table_size () const { |
| return obj.tail - obj.head; |
| } |
| |
| 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; |
| } |
| }; |
| |
| /* |
| * 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); |
| } |
| |
| /* |
| * Finds the set of nodes (placed into roots) that should be assigned unique spaces. |
| * More specifically this looks for the top most 24 bit or 32 bit links in the graph. |
| * Some special casing is done that is specific to the layout of GSUB/GPOS tables. |
| */ |
| void find_space_roots (hb_set_t& visited, hb_set_t& roots) |
| { |
| int root_index = (int) root_idx (); |
| for (int i = root_index; i >= 0; i--) |
| { |
| if (visited.has (i)) continue; |
| |
| // Only real links can form 32 bit spaces |
| for (auto& l : vertices_[i].obj.real_links) |
| { |
| if (l.is_signed || l.width < 3) |
| continue; |
| |
| if (i == root_index && l.width == 3) |
| // Ignore 24bit links from the root node, this skips past the single 24bit |
| // pointer to the lookup list. |
| continue; |
| |
| if (l.width == 3) |
| { |
| // A 24bit offset forms a root, unless there is 32bit offsets somewhere |
| // in it's subgraph, then those become the roots instead. This is to make sure |
| // that extension subtables beneath a 24bit lookup become the spaces instead |
| // of the offset to the lookup. |
| hb_set_t sub_roots; |
| find_32bit_roots (l.objidx, sub_roots); |
| if (sub_roots) { |
| for (unsigned sub_root_idx : sub_roots) { |
| roots.add (sub_root_idx); |
| find_subgraph (sub_root_idx, visited); |
| } |
| continue; |
| } |
| } |
| |
| roots.add (l.objidx); |
| find_subgraph (l.objidx, visited); |
| } |
| } |
| } |
| |
| unsigned index_for_offset(unsigned node_idx, const void* offset) const |
| { |
| const auto& node = object (node_idx); |
| if (offset < node.head || offset >= node.tail) return -1; |
| |
| for (const auto& link : node.real_links) |
| { |
| if (offset != node.head + link.position) |
| continue; |
| return link.objidx; |
| } |
| |
| return -1; |
| } |
| |
| |
| /* |
| * Assign unique space numbers to each connected subgraph of 24 bit and/or 32 bit offset(s). |
| * Currently, this is implemented specifically tailored to the structure of a GPOS/GSUB |
| * (including with 24bit offsets) table. |
| */ |
| bool assign_spaces () |
| { |
| update_parents (); |
| |
| hb_set_t visited; |
| hb_set_t roots; |
| find_space_roots (visited, roots); |
| |
| // Mark everything not in the subgraphs of the roots as visited. This prevents |
| // subgraphs from being connected via nodes not in those 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); |
| } |
| |
| size_t find_subgraph_size (unsigned node_idx, hb_set_t& subgraph, unsigned max_depth = -1) |
| { |
| if (subgraph.has (node_idx)) return 0; |
| subgraph.add (node_idx); |
| |
| const auto& o = vertices_[node_idx].obj; |
| size_t size = o.tail - o.head; |
| if (max_depth == 0) |
| return size; |
| |
| for (const auto& link : o.all_links ()) |
| size += find_subgraph_size (link.objidx, subgraph, max_depth - 1); |
| return size; |
| } |
| |
| /* |
| * Finds the topmost children of 32bit offsets in the subgraph starting |
| * at node_idx. Found indices are placed into 'found'. |
| */ |
| void find_32bit_roots (unsigned node_idx, hb_set_t& found) |
| { |
| for (const auto& link : vertices_[node_idx].obj.all_links ()) |
| { |
| if (!link.is_signed && link.width == 4) { |
| found.add (link.objidx); |
| continue; |
| } |
| find_32bit_roots (link.objidx, found); |
| } |
| } |
| |
| /* |
| * 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; |
| } |
| |
| |
| /* |
| * Adds a new node to the graph, not connected to anything. |
| */ |
| unsigned new_node (char* head, char* tail) |
| { |
| positions_invalid = true; |
| distance_invalid = true; |
| |
| auto* clone = vertices_.push (); |
| if (vertices_.in_error ()) { |
| return -1; |
| } |
| |
| clone->obj.head = head; |
| clone->obj.tail = tail; |
| clone->distance = 0; |
| clone->space = 0; |
| |
| unsigned clone_idx = vertices_.length - 2; |
| |
| // 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; |
| } |
| |
| /* |
| * 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; |
| } |
| |
| 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); |
| } |
| } |
| |
| 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 24 or 32 bits 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 == 3 || 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)); } |
| |
| public: |
| /* |
| * 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; |
| } |
| |
| private: |
| /* |
| * 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 |
