446 lines
15 KiB
C
446 lines
15 KiB
C
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//==========-- ImmutableGraph.h - A fast DAG implementation ---------=========//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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///
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/// Description: ImmutableGraph is a fast DAG implementation that cannot be
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/// modified, except by creating a new ImmutableGraph. ImmutableGraph is
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/// implemented as two arrays: one containing nodes, and one containing edges.
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/// The advantages to this implementation are two-fold:
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/// 1. Iteration and traversal operations benefit from cache locality.
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/// 2. Operations on sets of nodes/edges are efficient, and representations of
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/// those sets in memory are compact. For instance, a set of edges is
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/// implemented as a bit vector, wherein each bit corresponds to one edge in
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/// the edge array. This implies a lower bound of 64x spatial improvement
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/// over, e.g., an llvm::DenseSet or llvm::SmallSet. It also means that
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/// insert/erase/contains operations complete in negligible constant time:
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/// insert and erase require one load and one store, and contains requires
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/// just one load.
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///
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_TARGET_X86_IMMUTABLEGRAPH_H
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#define LLVM_LIB_TARGET_X86_IMMUTABLEGRAPH_H
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#include "llvm/ADT/BitVector.h"
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#include "llvm/ADT/GraphTraits.h"
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#include "llvm/ADT/STLExtras.h"
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#include <algorithm>
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#include <iterator>
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#include <utility>
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#include <vector>
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namespace llvm {
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template <typename NodeValueT, typename EdgeValueT> class ImmutableGraph {
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using Traits = GraphTraits<ImmutableGraph<NodeValueT, EdgeValueT> *>;
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template <typename> friend class ImmutableGraphBuilder;
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public:
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using node_value_type = NodeValueT;
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using edge_value_type = EdgeValueT;
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using size_type = int;
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class Node;
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class Edge {
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friend class ImmutableGraph;
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template <typename> friend class ImmutableGraphBuilder;
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const Node *Dest;
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edge_value_type Value;
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public:
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const Node *getDest() const { return Dest; };
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const edge_value_type &getValue() const { return Value; }
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};
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class Node {
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friend class ImmutableGraph;
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template <typename> friend class ImmutableGraphBuilder;
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const Edge *Edges;
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node_value_type Value;
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public:
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const node_value_type &getValue() const { return Value; }
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const Edge *edges_begin() const { return Edges; }
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// Nodes are allocated sequentially. Edges for a node are stored together.
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// The end of this Node's edges is the beginning of the next node's edges.
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// An extra node was allocated to hold the end pointer for the last real
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// node.
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const Edge *edges_end() const { return (this + 1)->Edges; }
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ArrayRef<Edge> edges() const {
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return makeArrayRef(edges_begin(), edges_end());
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}
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};
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protected:
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ImmutableGraph(std::unique_ptr<Node[]> Nodes, std::unique_ptr<Edge[]> Edges,
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size_type NodesSize, size_type EdgesSize)
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: Nodes(std::move(Nodes)), Edges(std::move(Edges)), NodesSize(NodesSize),
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EdgesSize(EdgesSize) {}
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ImmutableGraph(const ImmutableGraph &) = delete;
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ImmutableGraph(ImmutableGraph &&) = delete;
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ImmutableGraph &operator=(const ImmutableGraph &) = delete;
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ImmutableGraph &operator=(ImmutableGraph &&) = delete;
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public:
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ArrayRef<Node> nodes() const { return makeArrayRef(Nodes.get(), NodesSize); }
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const Node *nodes_begin() const { return nodes().begin(); }
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const Node *nodes_end() const { return nodes().end(); }
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ArrayRef<Edge> edges() const { return makeArrayRef(Edges.get(), EdgesSize); }
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const Edge *edges_begin() const { return edges().begin(); }
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const Edge *edges_end() const { return edges().end(); }
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size_type nodes_size() const { return NodesSize; }
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size_type edges_size() const { return EdgesSize; }
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// Node N must belong to this ImmutableGraph.
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size_type getNodeIndex(const Node &N) const {
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return std::distance(nodes_begin(), &N);
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}
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// Edge E must belong to this ImmutableGraph.
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size_type getEdgeIndex(const Edge &E) const {
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return std::distance(edges_begin(), &E);
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}
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// FIXME: Could NodeSet and EdgeSet be templated to share code?
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class NodeSet {
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const ImmutableGraph &G;
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BitVector V;
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public:
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NodeSet(const ImmutableGraph &G, bool ContainsAll = false)
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: G{G}, V{static_cast<unsigned>(G.nodes_size()), ContainsAll} {}
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bool insert(const Node &N) {
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size_type Idx = G.getNodeIndex(N);
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bool AlreadyExists = V.test(Idx);
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V.set(Idx);
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return !AlreadyExists;
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}
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void erase(const Node &N) {
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size_type Idx = G.getNodeIndex(N);
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V.reset(Idx);
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}
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bool contains(const Node &N) const {
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size_type Idx = G.getNodeIndex(N);
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return V.test(Idx);
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}
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void clear() { V.reset(); }
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size_type empty() const { return V.none(); }
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/// Return the number of elements in the set
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size_type count() const { return V.count(); }
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/// Return the size of the set's domain
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size_type size() const { return V.size(); }
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/// Set union
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NodeSet &operator|=(const NodeSet &RHS) {
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assert(&this->G == &RHS.G);
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V |= RHS.V;
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return *this;
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}
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/// Set intersection
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NodeSet &operator&=(const NodeSet &RHS) {
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assert(&this->G == &RHS.G);
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V &= RHS.V;
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return *this;
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}
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/// Set disjoint union
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NodeSet &operator^=(const NodeSet &RHS) {
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assert(&this->G == &RHS.G);
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V ^= RHS.V;
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return *this;
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}
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using index_iterator = typename BitVector::const_set_bits_iterator;
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index_iterator index_begin() const { return V.set_bits_begin(); }
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index_iterator index_end() const { return V.set_bits_end(); }
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void set(size_type Idx) { V.set(Idx); }
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void reset(size_type Idx) { V.reset(Idx); }
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class iterator {
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const NodeSet &Set;
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size_type Current;
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void advance() {
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assert(Current != -1);
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Current = Set.V.find_next(Current);
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}
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public:
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iterator(const NodeSet &Set, size_type Begin)
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: Set{Set}, Current{Begin} {}
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iterator operator++(int) {
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iterator Tmp = *this;
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advance();
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return Tmp;
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}
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iterator &operator++() {
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advance();
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return *this;
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}
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Node *operator*() const {
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assert(Current != -1);
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return Set.G.nodes_begin() + Current;
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}
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bool operator==(const iterator &other) const {
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assert(&this->Set == &other.Set);
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return this->Current == other.Current;
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}
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bool operator!=(const iterator &other) const { return !(*this == other); }
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};
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iterator begin() const { return iterator{*this, V.find_first()}; }
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iterator end() const { return iterator{*this, -1}; }
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};
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class EdgeSet {
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const ImmutableGraph &G;
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BitVector V;
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public:
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EdgeSet(const ImmutableGraph &G, bool ContainsAll = false)
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: G{G}, V{static_cast<unsigned>(G.edges_size()), ContainsAll} {}
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bool insert(const Edge &E) {
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size_type Idx = G.getEdgeIndex(E);
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bool AlreadyExists = V.test(Idx);
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V.set(Idx);
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return !AlreadyExists;
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}
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void erase(const Edge &E) {
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size_type Idx = G.getEdgeIndex(E);
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V.reset(Idx);
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}
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bool contains(const Edge &E) const {
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size_type Idx = G.getEdgeIndex(E);
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return V.test(Idx);
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}
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void clear() { V.reset(); }
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bool empty() const { return V.none(); }
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/// Return the number of elements in the set
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size_type count() const { return V.count(); }
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/// Return the size of the set's domain
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size_type size() const { return V.size(); }
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/// Set union
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EdgeSet &operator|=(const EdgeSet &RHS) {
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assert(&this->G == &RHS.G);
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V |= RHS.V;
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return *this;
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}
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/// Set intersection
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EdgeSet &operator&=(const EdgeSet &RHS) {
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assert(&this->G == &RHS.G);
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V &= RHS.V;
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return *this;
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}
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/// Set disjoint union
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EdgeSet &operator^=(const EdgeSet &RHS) {
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assert(&this->G == &RHS.G);
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V ^= RHS.V;
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return *this;
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}
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using index_iterator = typename BitVector::const_set_bits_iterator;
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index_iterator index_begin() const { return V.set_bits_begin(); }
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index_iterator index_end() const { return V.set_bits_end(); }
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void set(size_type Idx) { V.set(Idx); }
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void reset(size_type Idx) { V.reset(Idx); }
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class iterator {
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const EdgeSet &Set;
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size_type Current;
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void advance() {
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assert(Current != -1);
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Current = Set.V.find_next(Current);
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}
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public:
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iterator(const EdgeSet &Set, size_type Begin)
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: Set{Set}, Current{Begin} {}
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iterator operator++(int) {
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iterator Tmp = *this;
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advance();
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return Tmp;
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}
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iterator &operator++() {
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advance();
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return *this;
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}
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Edge *operator*() const {
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assert(Current != -1);
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return Set.G.edges_begin() + Current;
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}
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bool operator==(const iterator &other) const {
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assert(&this->Set == &other.Set);
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return this->Current == other.Current;
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}
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bool operator!=(const iterator &other) const { return !(*this == other); }
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};
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iterator begin() const { return iterator{*this, V.find_first()}; }
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iterator end() const { return iterator{*this, -1}; }
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};
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private:
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std::unique_ptr<Node[]> Nodes;
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std::unique_ptr<Edge[]> Edges;
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size_type NodesSize;
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size_type EdgesSize;
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};
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template <typename GraphT> class ImmutableGraphBuilder {
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using node_value_type = typename GraphT::node_value_type;
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using edge_value_type = typename GraphT::edge_value_type;
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static_assert(
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std::is_base_of<ImmutableGraph<node_value_type, edge_value_type>,
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GraphT>::value,
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"Template argument to ImmutableGraphBuilder must derive from "
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"ImmutableGraph<>");
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using size_type = typename GraphT::size_type;
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using NodeSet = typename GraphT::NodeSet;
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using Node = typename GraphT::Node;
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using EdgeSet = typename GraphT::EdgeSet;
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using Edge = typename GraphT::Edge;
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using BuilderEdge = std::pair<edge_value_type, size_type>;
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using EdgeList = std::vector<BuilderEdge>;
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using BuilderVertex = std::pair<node_value_type, EdgeList>;
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using VertexVec = std::vector<BuilderVertex>;
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public:
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using BuilderNodeRef = size_type;
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BuilderNodeRef addVertex(const node_value_type &V) {
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auto I = AdjList.emplace(AdjList.end(), V, EdgeList{});
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return std::distance(AdjList.begin(), I);
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}
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void addEdge(const edge_value_type &E, BuilderNodeRef From,
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BuilderNodeRef To) {
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AdjList[From].second.emplace_back(E, To);
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}
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bool empty() const { return AdjList.empty(); }
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template <typename... ArgT> std::unique_ptr<GraphT> get(ArgT &&... Args) {
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size_type VertexSize = AdjList.size(), EdgeSize = 0;
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for (const auto &V : AdjList) {
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EdgeSize += V.second.size();
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}
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auto VertexArray =
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std::make_unique<Node[]>(VertexSize + 1 /* terminator node */);
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auto EdgeArray = std::make_unique<Edge[]>(EdgeSize);
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size_type VI = 0, EI = 0;
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for (; VI < VertexSize; ++VI) {
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VertexArray[VI].Value = std::move(AdjList[VI].first);
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VertexArray[VI].Edges = &EdgeArray[EI];
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auto NumEdges = static_cast<size_type>(AdjList[VI].second.size());
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for (size_type VEI = 0; VEI < NumEdges; ++VEI, ++EI) {
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auto &E = AdjList[VI].second[VEI];
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EdgeArray[EI].Value = std::move(E.first);
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EdgeArray[EI].Dest = &VertexArray[E.second];
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}
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}
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assert(VI == VertexSize && EI == EdgeSize && "ImmutableGraph malformed");
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VertexArray[VI].Edges = &EdgeArray[EdgeSize]; // terminator node
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return std::make_unique<GraphT>(std::move(VertexArray),
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std::move(EdgeArray), VertexSize, EdgeSize,
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std::forward<ArgT>(Args)...);
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}
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template <typename... ArgT>
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static std::unique_ptr<GraphT> trim(const GraphT &G, const NodeSet &TrimNodes,
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const EdgeSet &TrimEdges,
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ArgT &&... Args) {
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size_type NewVertexSize = G.nodes_size() - TrimNodes.count();
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size_type NewEdgeSize = G.edges_size() - TrimEdges.count();
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auto NewVertexArray =
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std::make_unique<Node[]>(NewVertexSize + 1 /* terminator node */);
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auto NewEdgeArray = std::make_unique<Edge[]>(NewEdgeSize);
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// Walk the nodes and determine the new index for each node.
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size_type NewNodeIndex = 0;
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std::vector<size_type> RemappedNodeIndex(G.nodes_size());
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for (const Node &N : G.nodes()) {
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if (TrimNodes.contains(N))
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continue;
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RemappedNodeIndex[G.getNodeIndex(N)] = NewNodeIndex++;
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}
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assert(NewNodeIndex == NewVertexSize &&
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"Should have assigned NewVertexSize indices");
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size_type VertexI = 0, EdgeI = 0;
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for (const Node &N : G.nodes()) {
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if (TrimNodes.contains(N))
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continue;
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NewVertexArray[VertexI].Value = N.getValue();
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NewVertexArray[VertexI].Edges = &NewEdgeArray[EdgeI];
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for (const Edge &E : N.edges()) {
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if (TrimEdges.contains(E))
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continue;
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NewEdgeArray[EdgeI].Value = E.getValue();
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size_type DestIdx = G.getNodeIndex(*E.getDest());
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size_type NewIdx = RemappedNodeIndex[DestIdx];
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assert(NewIdx < NewVertexSize);
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NewEdgeArray[EdgeI].Dest = &NewVertexArray[NewIdx];
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++EdgeI;
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}
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++VertexI;
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}
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assert(VertexI == NewVertexSize && EdgeI == NewEdgeSize &&
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"Gadget graph malformed");
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NewVertexArray[VertexI].Edges = &NewEdgeArray[NewEdgeSize]; // terminator
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return std::make_unique<GraphT>(std::move(NewVertexArray),
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std::move(NewEdgeArray), NewVertexSize,
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NewEdgeSize, std::forward<ArgT>(Args)...);
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}
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private:
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VertexVec AdjList;
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};
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template <typename NodeValueT, typename EdgeValueT>
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struct GraphTraits<ImmutableGraph<NodeValueT, EdgeValueT> *> {
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using GraphT = ImmutableGraph<NodeValueT, EdgeValueT>;
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using NodeRef = typename GraphT::Node const *;
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using EdgeRef = typename GraphT::Edge const &;
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static NodeRef edge_dest(EdgeRef E) { return E.getDest(); }
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using ChildIteratorType =
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mapped_iterator<typename GraphT::Edge const *, decltype(&edge_dest)>;
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static NodeRef getEntryNode(GraphT *G) { return G->nodes_begin(); }
|
||
|
static ChildIteratorType child_begin(NodeRef N) {
|
||
|
return {N->edges_begin(), &edge_dest};
|
||
|
}
|
||
|
static ChildIteratorType child_end(NodeRef N) {
|
||
|
return {N->edges_end(), &edge_dest};
|
||
|
}
|
||
|
|
||
|
static NodeRef getNode(typename GraphT::Node const &N) { return NodeRef{&N}; }
|
||
|
using nodes_iterator =
|
||
|
mapped_iterator<typename GraphT::Node const *, decltype(&getNode)>;
|
||
|
static nodes_iterator nodes_begin(GraphT *G) {
|
||
|
return {G->nodes_begin(), &getNode};
|
||
|
}
|
||
|
static nodes_iterator nodes_end(GraphT *G) {
|
||
|
return {G->nodes_end(), &getNode};
|
||
|
}
|
||
|
|
||
|
using ChildEdgeIteratorType = typename GraphT::Edge const *;
|
||
|
|
||
|
static ChildEdgeIteratorType child_edge_begin(NodeRef N) {
|
||
|
return N->edges_begin();
|
||
|
}
|
||
|
static ChildEdgeIteratorType child_edge_end(NodeRef N) {
|
||
|
return N->edges_end();
|
||
|
}
|
||
|
static typename GraphT::size_type size(GraphT *G) { return G->nodes_size(); }
|
||
|
};
|
||
|
|
||
|
} // end namespace llvm
|
||
|
|
||
|
#endif // LLVM_LIB_TARGET_X86_IMMUTABLEGRAPH_H
|