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/*******************************************************************************
********************************************************************************
digraph : directed graph
Copyright © 2023 Yann Orlarey. All rights reserved.
*******************************************************************************
******************************************************************************/
#pragma once
#include <cassert>
#include <cstdint>
#include <cstdio>
#include <iostream>
#include <map>
#include <memory>
#include <set>
#include <stack>
//===========================================================
// digraph : a directed graph, a set of nodes f type N and a
// set of connections between these nodes. Connections have an
// associated value, by default 0. This value is used in Faust
// to represent the time dependency between computations.
//===========================================================
template <typename N>
class digraph {
using TWeights = std::set<int>;
using TDestinations = std::map<N, TWeights>;
static inline const TWeights gEmptyWeights;
//--------------------------------------------------------------------------
// Real/internal structure of a graph. A graph is a set of nodes
// and a set of connections between theses nodes. These connections
// have integer values attached.
class internalgraph {
private:
std::set<N> fNodes; // {n1,n2,...}
std::map<N, TDestinations> fConnections; // {(ni -{d1,d2,...}-> nj),...}
public:
#if 0
internalgraph() { std::cout << "create internalgraph " << this << '\n'; }
~internalgraph() { std::cout << "delete internalgraph " << this << '\n'; }
#endif
//----------------------------------------------------------------------
// Methods used to build the graph
//----------------------------------------------------------------------
// Add a node n to the graph
void add(N n)
{
fNodes.insert(n);
(void)fConnections[n]; // make sure we have an empty set of connections for n
}
// add two nodes with a set of connections of weights w
void add(const N& n1, const N& n2, const TWeights& w)
{
add(n1);
add(n2);
fConnections[n1][n2].insert(w.begin(), w.end());
}
//----------------------------------------------------------------------
// Methods used to query the graph
//----------------------------------------------------------------------
// returns the set of nodes of the graph
[[nodiscard]] const std::set<N>& nodes() const { return fNodes; }
// returns the set of nodes of the graph
[[nodiscard]] const std::map<N, TDestinations>& connections() const { return fConnections; }
// Returns the destinations of node n in the graph
[[nodiscard]] const TDestinations& destinations(const N& n) const
{
assert(fNodes.find(n) != fNodes.end());
return fConnections.at(n);
}
// Returns true is n1 and n2 are connected in the graph
[[nodiscard]] bool areConnected(const N& n1, const N& n2) const
{
// check we test connexions between existing nodes
assert(fNodes.find(n1) != fNodes.end());
assert(fNodes.find(n2) != fNodes.end());
auto cnx1 = fConnections.find(n1);
if (cnx1 == fConnections.end()) {
// n1 has no connection
return false;
} else {
auto cnx2 = cnx1->second.find(n2);
if (cnx2 == cnx1->second.end()) {
// n1 has connections, but not to n2
return false;
} else {
// its seems we have connections between n1 and n2,
// but we need to check
const std::set<int>& w12 = cnx2->second;
return !w12.empty();
}
}
}
// Returns the destinations of node n in the graph
[[nodiscard]] bool areConnected(const N& n1, const N& n2, int& d) const
{
// check we test connexions between existing nodes
assert(fNodes.find(n1) != fNodes.end());
assert(fNodes.find(n2) != fNodes.end());
auto cnx1 = fConnections.find(n1);
if (cnx1 == fConnections.end()) {
// n1 has no connection
return false;
} else {
auto cnx2 = cnx1->second.find(n2);
if (cnx2 == cnx1->second.end()) {
// n1 has connections, but not to n2
return false;
} else {
// its seems we have connections between n1 and n2,
// but we need to check
const std::set<int>& w12 = cnx2->second;
if (!w12.empty()) {
d = *w12.begin();
return true;
} else {
return false;
}
}
}
}
// Returns the weights of the connections between two nodes
[[nodiscard]] const TWeights& weights(const N& n1, const N& n2) const
{
// check we test connexions between existing nodes
assert(fNodes.find(n1) != fNodes.end());
assert(fNodes.find(n2) != fNodes.end());
auto cnx1 = fConnections.find(n1);
if (cnx1 == fConnections.end()) {
// n1 has no connection
return gEmptyWeights;
} else {
auto cnx2 = cnx1->second.find(n2);
if (cnx2 == cnx1->second.end()) {
// n1 has connections, but not to n2
return gEmptyWeights;
} else {
// its seems we have connections between n1 and n2,
// but we need to check
const std::set<int>& w12 = cnx2->second;
return w12;
}
}
}
};
std::shared_ptr<internalgraph> fContent = std::make_shared<internalgraph>();
public:
//--------------------------------------------------------------------------
// Methods used to build the graph
//--------------------------------------------------------------------------
// Add the node n to the graph
digraph& add(N n)
{
fContent->add(n);
return *this;
}
// add two nodes with a set of connections of weights w
digraph& add(const N& n1, const N& n2, const TWeights& w)
{
fContent->add(n1, n2, w);
return *this;
}
// Add the nodes n1 and n2 and the connection (n1 -d-> n2) to the graph.
digraph& add(const N& n1, const N& n2, int d = 0)
{
fContent->add(n1, n2, {d});
return *this;
}
// add a whole graph g
digraph& add(const digraph& g)
{
for (auto& n : g.nodes()) {
add(n);
for (auto& c : g.destinations(n)) {
add(n, c.first, c.second);
}
}
return *this;
}
//--------------------------------------------------------------------------
// Methods used to visit the graph
//--------------------------------------------------------------------------
// returns the set of nodes of the graph
[[nodiscard]] const std::set<N>& nodes() const { return fContent->nodes(); }
// returns the set of nodes of the graph
[[nodiscard]] const std::map<N, TDestinations>& connections() const
{
return fContent->connections();
}
// returns the destinations of node n in the graph
[[nodiscard]] const TDestinations& destinations(const N& n) const
{
return fContent->destinations(n);
}
// returns the weights of the connections between two nodes
[[nodiscard]] const TWeights& weights(const N& n1, const N& n2) const
{
return fContent->weights(n1, n2);
}
//--------------------------------------------------------------------------
// Methods used to query the graph
//--------------------------------------------------------------------------
// true is there is any connection between nodes n1 and n2
[[nodiscard]] bool areConnected(const N& n1, const N& n2) const
{
return fContent->areConnected(n1, n2);
}
// true is there is any connection between nodes n1 and n2.
// The smallest weight is returned in d.
bool areConnected(const N& n1, const N& n2, int& d) const
{
return fContent->areConnected(n1, n2, d);
}
//--------------------------------------------------------------------------
// compare graphs for maps and other containers
//--------------------------------------------------------------------------
friend bool operator<(const digraph& p1, const digraph& p2)
{
return (p1.nodes() < p2.nodes()) ||
((p1.nodes() == p2.nodes()) && (p1.connections() < p2.connections()));
}
friend bool operator==(const digraph& p1, const digraph& p2)
{
return p1.nodes() == p2.nodes() && p1.connections() == p2.connections();
}
};
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