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251 lines
7.6 KiB
251 lines
7.6 KiB
//===- llvm/unittest/ADT/TestGraph.h - Graph for testing ------------------===//
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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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// Common graph data structure for testing.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_UNITTESTS_ADT_TEST_GRAPH_H
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#define LLVM_UNITTESTS_ADT_TEST_GRAPH_H
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#include "llvm/ADT/GraphTraits.h"
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#include <cassert>
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#include <climits>
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#include <utility>
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namespace llvm {
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/// Graph<N> - A graph with N nodes. Note that N can be at most 8.
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template <unsigned N>
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class Graph {
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private:
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// Disable copying.
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Graph(const Graph&);
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Graph& operator=(const Graph&);
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static void ValidateIndex(unsigned Idx) {
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assert(Idx < N && "Invalid node index!");
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}
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public:
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/// NodeSubset - A subset of the graph's nodes.
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class NodeSubset {
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typedef unsigned char BitVector; // Where the limitation N <= 8 comes from.
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BitVector Elements;
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NodeSubset(BitVector e) : Elements(e) {}
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public:
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/// NodeSubset - Default constructor, creates an empty subset.
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NodeSubset() : Elements(0) {
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assert(N <= sizeof(BitVector)*CHAR_BIT && "Graph too big!");
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}
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/// Comparison operators.
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bool operator==(const NodeSubset &other) const {
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return other.Elements == this->Elements;
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}
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bool operator!=(const NodeSubset &other) const {
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return !(*this == other);
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}
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/// AddNode - Add the node with the given index to the subset.
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void AddNode(unsigned Idx) {
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ValidateIndex(Idx);
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Elements |= 1U << Idx;
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}
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/// DeleteNode - Remove the node with the given index from the subset.
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void DeleteNode(unsigned Idx) {
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ValidateIndex(Idx);
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Elements &= ~(1U << Idx);
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}
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/// count - Return true if the node with the given index is in the subset.
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bool count(unsigned Idx) {
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ValidateIndex(Idx);
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return (Elements & (1U << Idx)) != 0;
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}
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/// isEmpty - Return true if this is the empty set.
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bool isEmpty() const {
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return Elements == 0;
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}
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/// isSubsetOf - Return true if this set is a subset of the given one.
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bool isSubsetOf(const NodeSubset &other) const {
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return (this->Elements | other.Elements) == other.Elements;
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}
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/// Complement - Return the complement of this subset.
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NodeSubset Complement() const {
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return ~(unsigned)this->Elements & ((1U << N) - 1);
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}
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/// Join - Return the union of this subset and the given one.
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NodeSubset Join(const NodeSubset &other) const {
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return this->Elements | other.Elements;
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}
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/// Meet - Return the intersection of this subset and the given one.
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NodeSubset Meet(const NodeSubset &other) const {
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return this->Elements & other.Elements;
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}
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};
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/// NodeType - Node index and set of children of the node.
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typedef std::pair<unsigned, NodeSubset> NodeType;
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private:
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/// Nodes - The list of nodes for this graph.
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NodeType Nodes[N];
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public:
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/// Graph - Default constructor. Creates an empty graph.
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Graph() {
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// Let each node know which node it is. This allows us to find the start of
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// the Nodes array given a pointer to any element of it.
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for (unsigned i = 0; i != N; ++i)
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Nodes[i].first = i;
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}
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/// AddEdge - Add an edge from the node with index FromIdx to the node with
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/// index ToIdx.
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void AddEdge(unsigned FromIdx, unsigned ToIdx) {
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ValidateIndex(FromIdx);
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Nodes[FromIdx].second.AddNode(ToIdx);
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}
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/// DeleteEdge - Remove the edge (if any) from the node with index FromIdx to
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/// the node with index ToIdx.
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void DeleteEdge(unsigned FromIdx, unsigned ToIdx) {
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ValidateIndex(FromIdx);
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Nodes[FromIdx].second.DeleteNode(ToIdx);
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}
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/// AccessNode - Get a pointer to the node with the given index.
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NodeType *AccessNode(unsigned Idx) const {
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ValidateIndex(Idx);
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// The constant cast is needed when working with GraphTraits, which insists
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// on taking a constant Graph.
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return const_cast<NodeType *>(&Nodes[Idx]);
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}
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/// NodesReachableFrom - Return the set of all nodes reachable from the given
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/// node.
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NodeSubset NodesReachableFrom(unsigned Idx) const {
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// This algorithm doesn't scale, but that doesn't matter given the small
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// size of our graphs.
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NodeSubset Reachable;
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// The initial node is reachable.
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Reachable.AddNode(Idx);
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do {
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NodeSubset Previous(Reachable);
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// Add in all nodes which are children of a reachable node.
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for (unsigned i = 0; i != N; ++i)
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if (Previous.count(i))
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Reachable = Reachable.Join(Nodes[i].second);
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// If nothing changed then we have found all reachable nodes.
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if (Reachable == Previous)
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return Reachable;
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// Rinse and repeat.
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} while (1);
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}
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/// ChildIterator - Visit all children of a node.
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class ChildIterator {
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friend class Graph;
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/// FirstNode - Pointer to first node in the graph's Nodes array.
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NodeType *FirstNode;
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/// Children - Set of nodes which are children of this one and that haven't
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/// yet been visited.
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NodeSubset Children;
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ChildIterator(); // Disable default constructor.
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protected:
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ChildIterator(NodeType *F, NodeSubset C) : FirstNode(F), Children(C) {}
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public:
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/// ChildIterator - Copy constructor.
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ChildIterator(const ChildIterator &other) = default;
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ChildIterator &operator=(const ChildIterator &other) = default;
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/// Comparison operators.
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bool operator==(const ChildIterator &other) const {
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return other.FirstNode == this->FirstNode &&
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other.Children == this->Children;
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}
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bool operator!=(const ChildIterator &other) const {
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return !(*this == other);
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}
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/// Prefix increment operator.
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ChildIterator& operator++() {
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// Find the next unvisited child node.
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for (unsigned i = 0; i != N; ++i)
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if (Children.count(i)) {
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// Remove that child - it has been visited. This is the increment!
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Children.DeleteNode(i);
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return *this;
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}
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assert(false && "Incrementing end iterator!");
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return *this; // Avoid compiler warnings.
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}
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/// Postfix increment operator.
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ChildIterator operator++(int) {
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ChildIterator Result(*this);
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++(*this);
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return Result;
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}
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/// Dereference operator.
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NodeType *operator*() {
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// Find the next unvisited child node.
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for (unsigned i = 0; i != N; ++i)
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if (Children.count(i))
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// Return a pointer to it.
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return FirstNode + i;
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assert(false && "Dereferencing end iterator!");
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return nullptr; // Avoid compiler warning.
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}
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};
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/// child_begin - Return an iterator pointing to the first child of the given
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/// node.
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static ChildIterator child_begin(NodeType *Parent) {
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return ChildIterator(Parent - Parent->first, Parent->second);
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}
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/// child_end - Return the end iterator for children of the given node.
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static ChildIterator child_end(NodeType *Parent) {
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return ChildIterator(Parent - Parent->first, NodeSubset());
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}
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};
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template <unsigned N>
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struct GraphTraits<Graph<N> > {
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typedef typename Graph<N>::NodeType *NodeRef;
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typedef typename Graph<N>::ChildIterator ChildIteratorType;
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static NodeRef getEntryNode(const Graph<N> &G) { return G.AccessNode(0); }
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static ChildIteratorType child_begin(NodeRef Node) {
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return Graph<N>::child_begin(Node);
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}
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static ChildIteratorType child_end(NodeRef Node) {
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return Graph<N>::child_end(Node);
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}
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};
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} // End namespace llvm
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#endif
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