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PMD is an extensible multilanguage static code analyzer. It finds common programming flaws like unused variables, empty catch blocks, unnecessary object creation, and so forth. It's mainly concerned with Java and Apex, but supports 16 other languages. It comes with 400+ built-in rules. It can be extended with custom rules. It uses JavaCC and Antlr to parse source files into abstract syntax trees (AST) and runs rules against them to find violations. Rules can be written in Java or using a XPath query. Currently, PMD supports Java, JavaScript, Salesforce.com Apex and Visualforce, Kotlin, Swift, Modelica, PLSQL, Apache Velocity, JSP, WSDL, Maven POM, HTML, XML and XSL. Scala is supported, but there are currently no Scala rules available. Additionally, it includes CPD, the copy-paste-detector. CPD finds duplicated code in Coco, C/C++, C#, Dart, Fortran, Gherkin, Go, Groovy, HTML, Java, JavaScript, JSP, Julia, Kotlin, Lua, Matlab, Modelica, Objective-C, Perl, PHP, PLSQL, Python, Ruby, Salesforce.com Apex and Visualforce, Scala, Swift, T-SQL, Typescript, Apache Velocity, WSDL, XML and XSL.

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/*
 * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
 */


package net.sourceforge.pmd.util;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.function.Function;

import org.checkerframework.checker.nullness.qual.NonNull;

public final class GraphUtil {

    private GraphUtil() {

    }


    /**
     * Generate a DOT representation for a graph.
     *
     * @param vertices     Set of vertices
     * @param successorFun Function fetching successors
     * @param colorFun     Color of vertex box
     * @param labelFun     Vertex label
     * @param           Type of vertex, must be usable as map key (equals/hash)
     */
    public static  String toDot(
        Collection vertices,
        Function> successorFun,
        Function colorFun,
        Function labelFun
    ) {
        // generates a DOT representation of the lattice
        // Visualize eg at http://webgraphviz.com/
        StringBuilder sb = new StringBuilder("strict digraph {\n");
        Map ids = new HashMap<>();
        int i = 0;
        List vertexList = new ArrayList<>(vertices);
        vertexList.sort(Comparator.comparing(Object::toString)); // for reproducibility in tests
        for (V node : vertexList) {
            String id = "n" + i++;
            ids.put(node, id);
            sb.append(id)
              .append(" [ shape=box, color=")
              .append(colorFun.apply(node).toDot())
              .append(", label=\"")
              .append(escapeDotString(labelFun.apply(node)))
                .append("\" ];\n");
        }

        List edges = new ArrayList<>();

        for (V node : vertexList) {
            // edges
            String id = ids.get(node);
            for (V succ : successorFun.apply(node)) {
                String succId = ids.get(succ);
                edges.add(id + " -> " + succId + ";\n");
            }
        }

        edges.sort(Comparator.naturalOrder()); // for reproducibility in tests
        edges.forEach(sb::append);

        return sb.append('}').toString();
    }


    @NonNull
    private static String escapeDotString(String string) {
        return string.replaceAll("\\R", "\\\n")
                     .replaceAll("\"", "\\\"");
    }

    public enum DotColor {
        GREEN, BLACK;

        String toDot() {
            return name().toLowerCase(Locale.ROOT);
        }
    }

}