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| //===- llvm/unittest/ADT/TestGraph.h - Graph for testing ------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Common graph data structure for testing.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_UNITTESTS_ADT_TEST_GRAPH_H
#define LLVM_UNITTESTS_ADT_TEST_GRAPH_H
#include "llvm/ADT/GraphTraits.h"
#include <cassert>
#include <climits>
#include <utility>
namespace llvm {
/// Graph<N> - A graph with N nodes. Note that N can be at most 8.
template <unsigned N>
class Graph {
private:
// Disable copying.
Graph(const Graph&);
Graph& operator=(const Graph&);
static void ValidateIndex(unsigned Idx) {
assert(Idx < N && "Invalid node index!");
}
public:
/// NodeSubset - A subset of the graph's nodes.
class NodeSubset {
typedef unsigned char BitVector; // Where the limitation N <= 8 comes from.
BitVector Elements;
NodeSubset(BitVector e) : Elements(e) {}
public:
/// NodeSubset - Default constructor, creates an empty subset.
NodeSubset() : Elements(0) {
assert(N <= sizeof(BitVector)*CHAR_BIT && "Graph too big!");
}
/// Comparison operators.
bool operator==(const NodeSubset &other) const {
return other.Elements == this->Elements;
}
bool operator!=(const NodeSubset &other) const {
return !(*this == other);
}
/// AddNode - Add the node with the given index to the subset.
void AddNode(unsigned Idx) {
ValidateIndex(Idx);
Elements |= 1U << Idx;
}
/// DeleteNode - Remove the node with the given index from the subset.
void DeleteNode(unsigned Idx) {
ValidateIndex(Idx);
Elements &= ~(1U << Idx);
}
/// count - Return true if the node with the given index is in the subset.
bool count(unsigned Idx) {
ValidateIndex(Idx);
return (Elements & (1U << Idx)) != 0;
}
/// isEmpty - Return true if this is the empty set.
bool isEmpty() const {
return Elements == 0;
}
/// isSubsetOf - Return true if this set is a subset of the given one.
bool isSubsetOf(const NodeSubset &other) const {
return (this->Elements | other.Elements) == other.Elements;
}
/// Complement - Return the complement of this subset.
NodeSubset Complement() const {
return ~(unsigned)this->Elements & ((1U << N) - 1);
}
/// Join - Return the union of this subset and the given one.
NodeSubset Join(const NodeSubset &other) const {
return this->Elements | other.Elements;
}
/// Meet - Return the intersection of this subset and the given one.
NodeSubset Meet(const NodeSubset &other) const {
return this->Elements & other.Elements;
}
};
/// NodeType - Node index and set of children of the node.
typedef std::pair<unsigned, NodeSubset> NodeType;
private:
/// Nodes - The list of nodes for this graph.
NodeType Nodes[N];
public:
/// Graph - Default constructor. Creates an empty graph.
Graph() {
// Let each node know which node it is. This allows us to find the start of
// the Nodes array given a pointer to any element of it.
for (unsigned i = 0; i != N; ++i)
Nodes[i].first = i;
}
/// AddEdge - Add an edge from the node with index FromIdx to the node with
/// index ToIdx.
void AddEdge(unsigned FromIdx, unsigned ToIdx) {
ValidateIndex(FromIdx);
Nodes[FromIdx].second.AddNode(ToIdx);
}
/// DeleteEdge - Remove the edge (if any) from the node with index FromIdx to
/// the node with index ToIdx.
void DeleteEdge(unsigned FromIdx, unsigned ToIdx) {
ValidateIndex(FromIdx);
Nodes[FromIdx].second.DeleteNode(ToIdx);
}
/// AccessNode - Get a pointer to the node with the given index.
NodeType *AccessNode(unsigned Idx) const {
ValidateIndex(Idx);
// The constant cast is needed when working with GraphTraits, which insists
// on taking a constant Graph.
return const_cast<NodeType *>(&Nodes[Idx]);
}
/// NodesReachableFrom - Return the set of all nodes reachable from the given
/// node.
NodeSubset NodesReachableFrom(unsigned Idx) const {
// This algorithm doesn't scale, but that doesn't matter given the small
// size of our graphs.
NodeSubset Reachable;
// The initial node is reachable.
Reachable.AddNode(Idx);
do {
NodeSubset Previous(Reachable);
// Add in all nodes which are children of a reachable node.
for (unsigned i = 0; i != N; ++i)
if (Previous.count(i))
Reachable = Reachable.Join(Nodes[i].second);
// If nothing changed then we have found all reachable nodes.
if (Reachable == Previous)
return Reachable;
// Rinse and repeat.
} while (1);
}
/// ChildIterator - Visit all children of a node.
class ChildIterator {
friend class Graph;
/// FirstNode - Pointer to first node in the graph's Nodes array.
NodeType *FirstNode;
/// Children - Set of nodes which are children of this one and that haven't
/// yet been visited.
NodeSubset Children;
ChildIterator(); // Disable default constructor.
protected:
ChildIterator(NodeType *F, NodeSubset C) : FirstNode(F), Children(C) {}
public:
/// ChildIterator - Copy constructor.
ChildIterator(const ChildIterator& other) : FirstNode(other.FirstNode),
Children(other.Children) {}
/// Comparison operators.
bool operator==(const ChildIterator &other) const {
return other.FirstNode == this->FirstNode &&
other.Children == this->Children;
}
bool operator!=(const ChildIterator &other) const {
return !(*this == other);
}
/// Prefix increment operator.
ChildIterator& operator++() {
// Find the next unvisited child node.
for (unsigned i = 0; i != N; ++i)
if (Children.count(i)) {
// Remove that child - it has been visited. This is the increment!
Children.DeleteNode(i);
return *this;
}
assert(false && "Incrementing end iterator!");
return *this; // Avoid compiler warnings.
}
/// Postfix increment operator.
ChildIterator operator++(int) {
ChildIterator Result(*this);
++(*this);
return Result;
}
/// Dereference operator.
NodeType *operator*() {
// Find the next unvisited child node.
for (unsigned i = 0; i != N; ++i)
if (Children.count(i))
// Return a pointer to it.
return FirstNode + i;
assert(false && "Dereferencing end iterator!");
return nullptr; // Avoid compiler warning.
}
};
/// child_begin - Return an iterator pointing to the first child of the given
/// node.
static ChildIterator child_begin(NodeType *Parent) {
return ChildIterator(Parent - Parent->first, Parent->second);
}
/// child_end - Return the end iterator for children of the given node.
static ChildIterator child_end(NodeType *Parent) {
return ChildIterator(Parent - Parent->first, NodeSubset());
}
};
template <unsigned N>
struct GraphTraits<Graph<N> > {
typedef typename Graph<N>::NodeType *NodeRef;
typedef typename Graph<N>::ChildIterator ChildIteratorType;
static NodeRef getEntryNode(const Graph<N> &G) { return G.AccessNode(0); }
static ChildIteratorType child_begin(NodeRef Node) {
return Graph<N>::child_begin(Node);
}
static ChildIteratorType child_end(NodeRef Node) {
return Graph<N>::child_end(Node);
}
};
} // End namespace llvm
#endif
|