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JQF: Feedback-directed Quickcheck for Java - Sample generators and benchmark tests
/*
* Copyright (c) 2017-2018 The Regents of the University of California
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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package edu.berkeley.cs.jqf.examples.jgrapht;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;
import org.jgrapht.DirectedGraph;
import org.jgrapht.EdgeFactory;
import org.jgrapht.Graph;
import org.jgrapht.VertexFactory;
import org.jgrapht.generate.GraphGenerator;
/**
* @author Rohan Padhye
*/
public class FastGnmRandomGraphGenerator implements GraphGenerator {
private int n;
private int m;
private boolean loops;
private Random rng;
public FastGnmRandomGraphGenerator(int n, int m, Random rng, boolean loops) {
this.n = n;
this.m = m;
this.loops = loops;
this.rng = rng;
}
private int numEdges(boolean isDirected, boolean loops) {
if (loops) {
if (isDirected) {
return n * n;
} else {
return (n * (n + 1)) / 2;
}
} else {
if (isDirected) {
return n * (n - 1);
} else {
return (n * (n - 1)) / 2;
}
}
}
@Override
public void generateGraph(Graph graph, VertexFactory vertexFactory, Map map) {
// Create nodes
V[] nodes = (V[]) new Object[n];
for (int i = 0; i < n; i++) {
V v = vertexFactory.createVertex();
nodes[i] = v;
graph.addVertex(v);
}
// Collect ALL edges into a list
boolean isDirected = graph instanceof DirectedGraph;
int maxEdges = numEdges(isDirected, loops);
if (m > maxEdges) {
throw new IllegalArgumentException("Cannot generate " + m + " edges; " +
"max allowed is " + maxEdges);
}
E[] edges = (E[]) new Object[maxEdges];
EdgeFactory edgeFactory = graph.getEdgeFactory();
Map sources = new HashMap<>();
Map targets = new HashMap<>();
int k = 0;
for (int i = 0; i < n; i++) {
int start = isDirected ? 0 : i;
for (int j = start; j < n; j++) {
if (i != j || loops) {
V source = nodes[i];
V target = nodes[j];
E e = edgeFactory.createEdge(source, target);
edges[k++] = e;
sources.put(e, source);
targets.put(e, target);
}
}
}
assert(k == maxEdges);
// Select `m` edges to add
int available = maxEdges;
for (int i = 0; i < m; i++) {
// Select an edge in [0, available)
int idx = rng.nextInt(available);
E e = edges[idx];
graph.addEdge(sources.get(e), targets.get(e), e);
// Decrement upper bound and fill gap
available--;
edges[idx] = edges[available];
}
}
}