[#674] Implement automatic loading of extensions from working directory

README.md

@@ -155,7 +155,8 @@ not generate anything.
 Each Zserio extension should be packed in a single jar file.
 
 All Zserio extensions which are available on the Java classpath are automatically loaded during Zserio compiler
-startup.
+startup. Extensions which are located in the directory from which the Zserio jar executable has been run and
+which are named with the prefix `zserio_` are automatically loaded as well.
 
 More information how to implement a new Zserio extension can be found in the
 [Zserio extension sample](https://github.com/ndsev/zserio-extension-sample#zserio-extension-sample).

ant_task/src/zserio/ant/ToolWrapper.java

@@ -1,5 +1,6 @@
 package zserio.ant;
 
+import java.io.File;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.net.MalformedURLException;
@@ -40,25 +41,16 @@ public ToolWrapper(String className, Iterable<Path> classPath, boolean ignoreErr
             String [] files = p.list();
             for (String f : files)
             {
-                String u = null;
                 try
                 {
-                    if (f.endsWith(".jar"))
-                    {
-                        u = "jar:file:"+f+"!/";
-                    }
-                    else
-                    {
-                        u = "file:"+f+"/";
-                    }
-
-                    System.out.println("Adding " + u + " to classpath");
-                    urls.add(new URL(u));
+                    final URL pathUrl = new File(f).toURI().toURL();
+                    System.out.println("Adding " + pathUrl + " to classpath");
+                    urls.add(pathUrl);
 
                 }
-                catch (MalformedURLException e)
+                catch (MalformedURLException | RuntimeException e)
                 {
-                    throw new BuildException("Malformed URL: " + u);
+                    throw new BuildException("Malformed URL from file: " + f + " (" + e + ")");
                 }
             }
         }

compiler/core/build.xml

@@ -81,7 +81,7 @@ spotbugs.home_dir       - Location of the spotbugs tool. If not set, spotbugs is
         <attribute name="package" default="zserio.antlr"/>
         <sequential>
             <echo message="Generating ANTLR 4 grammar: @{target}"/>
-            <java classname="org.antlr.v4.Tool" failonerror="true">
+            <java classname="org.antlr.v4.Tool" failonerror="true" fork="true">
                 <classpath>
                     <pathelement location="${3rdparty.jar_dir}/${3rdparty.antlr4.jar_file_name}"/>
                 </classpath>

compiler/core/src/zserio/tools/ExtensionManager.java

@@ -1,13 +1,23 @@
 package zserio.tools;
 
+import java.io.File;
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.io.StringWriter;
+import java.net.MalformedURLException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.nio.file.Path;
+import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 import java.util.ServiceLoader;
+import java.util.jar.JarFile;
+import java.util.jar.Manifest;
 
 import zserio.ast.Root;
 import zserio.extension.common.ZserioExtensionException;
@@ -26,7 +36,7 @@ public ExtensionManager(CommandLineArguments commandLineArguments)
     {
         extensions = new ArrayList<Extension>();
         this.commandLineArguments = commandLineArguments;
-        ServiceLoader<Extension> loader = ServiceLoader.load(Extension.class, getClass().getClassLoader());
+        final ServiceLoader<Extension> loader = ServiceLoader.load(Extension.class, getClassLoader());
         Iterator<Extension> it = loader.iterator();
         while (it.hasNext())
         {
@@ -94,6 +104,108 @@ public void callExtensions(Root rootNode, ExtensionParameters parameters) throws
         }
     }
 
+    private ClassLoader getClassLoader()
+    {
+        final ClassLoader currentClassLoader = getClass().getClassLoader();
+        final File workingDirectory = getWorkingDirectory();
+        if (workingDirectory == null)
+            return currentClassLoader;
+
+        final File[] fileList = workingDirectory.listFiles();
+        if (fileList == null)
+            return currentClassLoader;
+
+        final ArrayList<URL> urlArray = new ArrayList<URL>();
+        try
+        {
+            for (File file : fileList)
+            {
+                if (isFileZserioExtension(file))
+                {
+                    urlArray.add(file.toURI().toURL());
+                    urlArray.addAll(getDependentJarsFromManifest(file));
+                }
+            }
+        }
+        catch (MalformedURLException excpt)
+        {
+            return currentClassLoader;
+        }
+
+        final URLClassLoader urlClassLoader =
+                new URLClassLoader(urlArray.toArray(new URL[urlArray.size()]), currentClassLoader);
+
+        return urlClassLoader;
+    }
+
+    private File getWorkingDirectory()
+    {
+        try
+        {
+            final URI execUri = getClass().getProtectionDomain().getCodeSource().getLocation().toURI();
+            final Path execPath = Paths.get(execUri);
+            final Path execParentPath = execPath.getParent();
+
+            return (execParentPath == null) ? null : execParentPath.toFile();
+        }
+        catch (SecurityException | URISyntaxException excpt)
+        {
+            return null;
+        }
+    }
+
+    private boolean isFileZserioExtension(File file)
+    {
+        if (!file.isFile())
+            return false;
+
+        final String fileName = file.getName();
+        if (!fileName.endsWith(".jar"))
+            return false;
+
+        if (!fileName.startsWith("zserio_"))
+            return false;
+
+        if (fileName.equals("zserio_core.jar"))
+            return false;
+
+        if (fileName.endsWith("_javadocs.jar"))
+            return false;
+
+        if (fileName.endsWith("_sources.jar"))
+            return false;
+
+        return true;
+    }
+
+    private List<URL> getDependentJarsFromManifest(File file)
+    {
+        final ArrayList<URL> dependentJars = new ArrayList<URL>();
+        try (JarFile jarFile = new JarFile(file))
+        {
+            final Manifest manifest = jarFile.getManifest();
+            if (manifest != null)
+            {
+                final String classPaths = manifest.getMainAttributes().getValue("class-path");
+                if (classPaths != null)
+                {
+                    final File parentFile = file.getParentFile();
+                    for (String classPath : classPaths.split("\\s+"))
+                    {
+                        final File dependentJarFile = new File(parentFile, classPath);
+                        dependentJars.add(dependentJarFile.toURI().toURL());
+                    }
+                }
+            }
+        }
+        catch (IOException excpt)
+        {
+            // silently ignored
+        }
+
+        return dependentJars;
+    }
+
     private static void check(Root rootNode, Extension extension, ExtensionParameters parameters)
             throws ZserioExtensionException
     {

test/core/build.xml

@@ -123,9 +123,7 @@ spotbugs.home_dir               - Location of the spotbugs tool. If not set, spo
             <zserio srcPath="${@{testName}.zs.in_dir}" srcFile="@{zsFile}" ignoreError="@{ignoreErrors}"
                     extraArgs="${zserio.extra_args}">
                 <classpath>
-                    <fileset dir="${zserio.jar_dir}">
-                        <include name="*.jar"/>
-                    </fileset>
+                    <file name="${zserio.jar_dir}/zserio_core.jar"/>
                 </classpath>
                 <args/>
             </zserio>

test/extensions/build.xml

@@ -138,9 +138,7 @@ spotbugs.home_dir               - Location of the spotbugs tool. If not set, spo
             <zserio srcPath="${@{testName}.zs.in_dir}" srcFile="@{zsFile}" ignoreError="@{ignoreErrors}"
                     extraArgs="${zserio.extra_args}">
                 <classpath>
-                    <fileset dir="${zserio.jar_dir}">
-                        <include name="*.jar"/>
-                    </fileset>
+                    <file name="${zserio.jar_dir}/zserio_core.jar"/>
                 </classpath>
                 <arg name="java" value="${@{testName}.zs.out_dir}"/>
                 <args/>