Add uncommited generation checking to all the gen tasks.

If checking="true" on them, they generate their code to a String instead of a file, and compare that
against existing output.  If any generation would produce changes, the build is failed.

As a side effect, generation will now only write files if it's going to modify them, which should
eliminate some spurious compiling.



git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@6349 542714f4-19e9-0310-aa3c-eee0fc999fb1

build.xml

@@ -47,6 +47,8 @@
   </target>
 
   <target name="-preptools" depends="-prepare">
+    <!-- Turn off generation checking if enablegencheck hasn't already set this property -->
+    <property name="gencheck" value="false"/>
     <javac srcdir="${src.dir}" destdir="${classes.dir}" includeAntRuntime="false"
            debug="on" optimize="${build.optimize}" deprecation="on"
            source="1.5" target="1.5" classpathref="compile.classpath">
@@ -214,6 +216,15 @@
     </grecord>
   </target>
 
+  <target name="enablegencheck"
+      description="Makes the code generators fail the build if they would produce new code">
+      <property name="gencheck" value="true"/>
+  </target>
+  <target name="gencheck" depends="enablegencheck,gencode"
+      description="Fails the build if any new code would be generated"/>
+  <target name="gencode" depends="gendobj,genservice,genreceiver,genstream"
+      description="Runs all code generators"/>
+
   <target name="gendobj" depends="-preptools"
           description="Generates additional methods for distributed object classes">
     <!-- make sure the dobject class files are all compiled -->
@@ -223,7 +234,7 @@
       <include name="**/*Object.java"/>
     </javac>
     <!-- now generate the associated files -->
-    <gendobj classpathref="built.classpath">
+    <gendobj classpathref="built.classpath" checking="${gencheck}">
       <fileset dir="${src.dir}" includes="**/*Object.java"/>
     </gendobj>
   </target>
@@ -238,7 +249,8 @@
       <exclude name="**/InvocationService.java"/>
     </javac>
     <!-- generate services with an actionscript counterpart-->
-    <genservice header="lib/SOURCE_HEADER" asroot="${asrc.dir}" classpathref="built.classpath">
+    <genservice header="lib/SOURCE_HEADER" asroot="${asrc.dir}" classpathref="built.classpath"
+        checking="${gencheck}">
       <fileset dir="${src.dir}" includes="**/*Service.java">
         <exclude name="**/RegistrationService.java"/>
         <exclude name="**/InvocationService.java"/>
@@ -250,8 +262,7 @@
       <providerless service="TimeBaseService"/>
     </genservice>
     <!-- generate java-only services -->
-    <genservice header="lib/SOURCE_HEADER" classpathref="built.classpath">
+    <genservice header="lib/SOURCE_HEADER" classpathref="built.classpath" checking="${gencheck}">
-      <fileset dir="${src.dir}" includes="**/RegistrationService.java"/>
       <fileset dir="${src.dir}" includes="**/peer/**/*Service.java"/>
       <fileset dir="${src.dir}" includes="**/admin/**/*Service.java"
           excludes="**/gwt/ConfigService.java"/>
@@ -271,17 +282,16 @@
       <exclude name="**/InvocationReceiver.java"/>
     </javac>
     <!-- now generate the associated files -->
-    <genreceiver header="lib/SOURCE_HEADER" classpathref="built.classpath">
+    <genreceiver header="lib/SOURCE_HEADER" classpathref="built.classpath" checking="${gencheck}">
       <fileset dir="${src.dir}" includes="**/*Receiver.java"
-        excludes="**/InvocationReceiver.java"/>
+        excludes="**/InvocationReceiver.java,**/SignalReceiver.java"/>
     </genreceiver>
   </target>
 
   <target name="genstream" depends="-preptools" description="Generates C++ streamable classes.">
-    <gencppstreamable classpathref="built.classpath" cpproot="src/cpp">
+    <gencppstreamable classpathref="built.classpath" cpproot="src/cpp" checking="${gencheck}">
       <generate class="com.threerings.presents.client.InvocationReceiver$Registration"/>
       <generate class="com.threerings.presents.data.ClientObject"/>
-      <generate class="com.threerings.presents.data.PermissionPolicy"/>
       <generate class="com.threerings.presents.dobj.DEvent"/>
       <generate class="com.threerings.presents.dobj.DObject"/>
       <generate class="com.threerings.presents.dobj.EntryAddedEvent"/>
@@ -320,13 +330,6 @@
     </instream>
   </target>
 
-  <target name="genascript" depends="-preptools"
-          description="Generates ActionScript versions of our Streamable classes">
-    <genascript header="lib/SOURCE_HEADER" asroot="${asrc.dir}">
-      <fileset dir="${src.dir}" includes="**/data/*.java"/>
-    </genascript>
-  </target>
-
   <target name="snapshot" description="Creates a zipfile with our source distribution">
      <delete file="${deploy.dir}/${ant.project.name}-snapshot.zip"/>
      <mkdir dir="${deploy.dir}/snapshot/${ant.project.name}"/>
@@ -349,7 +352,7 @@
   </target>
 
   <property name="maven.deploy.repo" value="file://${user.home}/.m2/repository"/>
-  <target name="maven-deploy" depends="dist,tests" 
+  <target name="maven-deploy" depends="dist,tests"
           description="Deploys our build artifacts to a Maven repository.">
     <artifact:deploy file="${deploy.dir}/${ant.project.name}.jar" uniqueVersion="false">
       <remoteRepository url="${maven.deploy.repo}"/>

src/cpp/presents/data/ClientObject.cpp

@@ -10,7 +10,6 @@ void ClientObject::readObject (ObjectInputStream& in)
     presents::dobj::DObject::readObject(in);
     username = boost::static_pointer_cast<util::Name>(in.readObject());
     receivers = boost::static_pointer_cast<presents::dobj::DSet>(in.readObject());
-    permPolicy = boost::static_pointer_cast<presents::data::PermissionPolicy>(in.readObject());
 }
 
 void ClientObject::writeObject (ObjectOutputStream& out) const
@@ -18,5 +17,4 @@ void ClientObject::writeObject (ObjectOutputStream& out) const
     presents::dobj::DObject::writeObject(out);
     out.writeObject(username);
     out.writeObject(receivers);
-    out.writeObject(permPolicy);
 }

src/cpp/presents/data/ClientObject.h

@@ -5,7 +5,6 @@
 #include "presents/ObjectOutputStream.h"
 #include "presents/streamers/StreamableStreamer.h"
 
-#include "presents/data/PermissionPolicy.h"
 #include "presents/dobj/DObject.h"
 #include "presents/dobj/DSet.h"
 #include "util/Name.h"
@@ -18,7 +17,6 @@ public:
 
     Shared<util::Name> username;
     Shared<presents::dobj::DSet> receivers;
-    Shared<presents::data::PermissionPolicy> permPolicy;
 
     virtual void readObject(ObjectInputStream& in);
     virtual void writeObject(ObjectOutputStream& out) const;

src/main/java/com/threerings/admin/web/client/ConfigFieldEditor.java

@@ -120,7 +120,7 @@ public abstract class ConfigFieldEditor
             resetField();
 
             _box.addValueChangeHandler(new ValueChangeHandler<Boolean>() {
-				public void onValueChange (ValueChangeEvent<Boolean> changeEvent) {
+                public void onValueChange (ValueChangeEvent<Boolean> changeEvent) {
                     updateModificationState();
                 }
             });
@@ -152,11 +152,11 @@ public abstract class ConfigFieldEditor
         _value = buildWidget(field);
 
         _name = new Label(field.name);
-		_name.setStyleName("fieldName");
+        _name.setStyleName("fieldName");
 
         _reset = new Label("X");
-		_reset.setStyleName("resetButton");
+        _reset.setStyleName("resetButton");
-		_reset.addClickHandler(new ClickHandler() {
+        _reset.addClickHandler(new ClickHandler() {
             public void onClick (ClickEvent event) {
                 resetField();
                 updateModificationState();
@@ -203,5 +203,5 @@ public abstract class ConfigFieldEditor
     protected Command _onChange;
 
     protected Label _name, _reset;
-	protected Widget _value;
+    protected Widget _value;
 }

src/main/java/com/threerings/admin/web/server/ConfigServlet.java

@@ -91,7 +91,7 @@ public abstract class ConfigServlet extends RemoteServiceServlet
     public ConfigurationRecord updateConfiguration (final String key, final ConfigField[] updates)
         throws ServiceException
     {
-		requireAdminUser();
+        requireAdminUser();
 
         final ServletWaiter<ConfigurationRecord> waiter =
             new ServletWaiter<ConfigurationRecord>("updateConfiguration");
@@ -156,11 +156,11 @@ public abstract class ConfigServlet extends RemoteServiceServlet
      * Implemented on a project by project basis to provide a security fence for configuration
      * editing powers.
      */
-	protected abstract void requireAdminUser ()
+    protected abstract void requireAdminUser ()
-		throws ServiceException;
+        throws ServiceException;
 
     @Inject protected ConfigRegistry _confReg;
-	@Inject protected RootDObjectManager _omgr;
+    @Inject protected RootDObjectManager _omgr;
 
     protected static Map<Class<?>, FieldType> TYPES = ImmutableMap.<Class<?>, FieldType>builder()
         .put(Integer.class, FieldType.INTEGER)

src/main/java/com/threerings/bureau/server/BureauSender.java

@@ -21,11 +21,10 @@
 
 package com.threerings.bureau.server;
 
-import com.threerings.presents.data.ClientObject;
-import com.threerings.presents.server.InvocationSender;
-
 import com.threerings.bureau.client.BureauDecoder;
 import com.threerings.bureau.client.BureauReceiver;
+import com.threerings.presents.data.ClientObject;
+import com.threerings.presents.server.InvocationSender;
 
 /**
  * Used to issue notifications to a {@link BureauReceiver} instance on a

src/main/java/com/threerings/crowd/server/LocationSender.java

@@ -21,11 +21,10 @@
 
 package com.threerings.crowd.server;
 
-import com.threerings.presents.data.ClientObject;
-import com.threerings.presents.server.InvocationSender;
-
 import com.threerings.crowd.client.LocationDecoder;
 import com.threerings.crowd.client.LocationReceiver;
+import com.threerings.presents.data.ClientObject;
+import com.threerings.presents.server.InvocationSender;
 
 /**
  * Used to issue notifications to a {@link LocationReceiver} instance on a

src/main/java/com/threerings/presents/tools/GenActionScriptStreamableTask.java

@@ -34,7 +34,6 @@ import org.apache.tools.ant.Project;
 
 import com.google.common.base.Charsets;
 import com.google.common.base.Joiner;
-import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Sets;
 import com.google.common.io.Files;
@@ -113,12 +112,8 @@ public class GenActionScriptStreamableTask extends GenTask
             // Merge in the previously generated version
             String existing = Files.toString(outputLocation, Charsets.UTF_8);
             output = new GeneratedSourceMerger().merge(output, existing);
-        } else if (!outputLocation.getParentFile().exists()) {
-            // Make sure the directory exists before trying to write there
-            Preconditions.checkArgument(outputLocation.getParentFile().mkdirs(),
-                "Unable to create directory to write '%s'", outputLocation.getAbsolutePath());
         }
-        Files.write(output, outputLocation, Charsets.UTF_8);
+        writeFile(outputLocation.getAbsolutePath(), output);
     }
 
     protected static class ASField

src/main/java/com/threerings/presents/tools/GenDObjectTask.java

@@ -21,20 +21,17 @@
 
 package com.threerings.presents.tools;
 
+import java.io.File;
 import java.lang.reflect.Field;
 import java.lang.reflect.Modifier;
 import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
-
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.Map;
 
-import java.io.File;
 import com.google.common.collect.Lists;
-
 import com.samskivert.util.StringUtil;
-
 import com.threerings.presents.annotation.TransportHint;
 import com.threerings.presents.dobj.DObject;
 import com.threerings.presents.dobj.DSet;
@@ -165,7 +162,7 @@ public class GenDObjectTask extends GenTask
         }
 
         // now bolt everything back together into a class declaration
-        sfile.writeTo(source, fsection.toString(), msection.toString());
+        writeFile(source.getAbsolutePath(), sfile.generate(fsection.toString(), msection.toString()));
     }
 
     /** {@link DObject} resolved with the proper classloader so that we

src/main/java/com/threerings/presents/tools/GenReceiverTask.java

@@ -114,11 +114,11 @@ public class GenReceiverTask extends InvocationTask
         String mpath = source.getPath();
         mpath = mpath.replace("Receiver", "Sender");
         mpath = replacePath(mpath, "/client/", "/server/");
-        writeFile(mpath, mergeTemplate(SENDER_TMPL,
+        writeTemplate(SENDER_TMPL, mpath,
-                                       "name", name,
+            "name", name,
-                                       "package", spackage,
+            "package", spackage,
-                                       "methods", methods,
+            "methods", methods,
-                                       "imports", implist));
+            "imports", implist);
     }
 
     protected void generateDecoder (Class<?> receiver, File source, String rname, String rpackage,
@@ -136,12 +136,12 @@ public class GenReceiverTask extends InvocationTask
         // determine the path to our sender file
         String mpath = source.getPath();
         mpath = mpath.replace("Receiver", "Decoder");
-        writeFile(mpath, mergeTemplate(DECODER_TMPL,
+        writeTemplate(DECODER_TMPL, mpath,
-                                       "name", name,
+            "name", name,
-                                       "receiver_code", rcode,
+            "receiver_code", rcode,
-                                       "package", rpackage,
+            "package", rpackage,
-                                       "methods", methods,
+            "methods", methods,
-                                       "imports", implist));
+            "imports", implist);
     }
 
     /** Specifies the path to the sender template. */

src/main/java/com/threerings/presents/tools/GenServiceTask.java

@@ -180,6 +180,14 @@ public class GenServiceTask extends InvocationTask
         }
     }
 
+    /**
+     * Configures to output extra information when generating code.
+     */
+    public void setVerbose (boolean verbose)
+    {
+        _verbose = verbose;
+    }
+
     /**
      * Configures the path to our ActionScript source files.
      */
@@ -280,7 +288,7 @@ public class GenServiceTask extends InvocationTask
         String mpath = source.getPath();
         mpath = mpath.replace("Service", "Marshaller");
         mpath = replacePath(mpath, "/client/", "/data/");
-        writeFile(mpath, mergeTemplate(MARSHALLER_TMPL, ctx));
+        writeTemplate(MARSHALLER_TMPL, mpath, ctx);
 
         // if we're not configured with an ActionScript source root, don't generate the
         // ActionScript versions
@@ -350,7 +358,7 @@ public class GenServiceTask extends InvocationTask
 
         // generate an ActionScript version of our marshaller
         String ampath = _asroot + File.separator + mppath + File.separator + mname + ".as";
-        writeFile(ampath, mergeTemplate(AS_MARSHALLER_TMPL, ctx));
+        writeTemplate(AS_MARSHALLER_TMPL, ampath, ctx);
 
         // ----------- Part III - as listener marshallers
 
@@ -387,7 +395,7 @@ public class GenServiceTask extends InvocationTask
             ctx.put("listener", listener);
             String aslpath = _asroot + File.separator + mppath +
                 File.separator + mname + "_" + listener.getListenerName() + "Marshaller.as";
-            writeFile(aslpath, mergeTemplate(AS_LISTENER_MARSHALLER_TMPL, ctx));
+            writeTemplate(AS_LISTENER_MARSHALLER_TMPL, aslpath, ctx);
         }
 
         // ----------- Part IV - as service
@@ -434,7 +442,7 @@ public class GenServiceTask extends InvocationTask
 
         // generate an ActionScript version of our service
         String aspath = _asroot + File.separator + sppath + File.separator + sname + ".as";
-        writeFile(aspath, mergeTemplate(AS_SERVICE_TMPL, ctx));
+        writeTemplate(AS_SERVICE_TMPL, aspath, ctx);
 
         // ----------- Part V - as service listeners
         Class<?> isil = InvocationService.InvocationListener.class;
@@ -471,12 +479,12 @@ public class GenServiceTask extends InvocationTask
 
             String aslpath = _asroot + File.separator + sppath + File.separator +
                 sname + "_" + listener.getListenerName() + "Listener.as";
-            writeFile(aslpath, mergeTemplate(AS_LISTENER_SERVICE_TMPL, ctx));
+            writeTemplate(AS_LISTENER_SERVICE_TMPL, aslpath, ctx);
 
             if (_aslistenerAdapters.contains(sname)) {
                 String aslapath = _asroot + File.separator + sppath + File.separator +
                     sname + "_" + listener.getListenerName() + "ListenerAdapter.as";
-                writeFile(aslapath, mergeTemplate(AS_LISTENER_ADAPTER_SERVICE_TMPL, ctx));
+                writeTemplate(AS_LISTENER_ADAPTER_SERVICE_TMPL, aslapath, ctx);
             }
         }
     }
@@ -531,12 +539,12 @@ public class GenServiceTask extends InvocationTask
         String mpath = source.getPath();
         mpath = mpath.replace("Service", "Dispatcher");
         mpath = replacePath(mpath, "/client/", "/server/");
-        writeFile(mpath, mergeTemplate(DISPATCHER_TMPL,
+        writeTemplate(DISPATCHER_TMPL, mpath,
-                                       "name", name,
+            "name", name,
-                                       "generated", getGeneratedAnnotation(name),
+            "generated", getGeneratedAnnotation(name),
-                                       "package", dpackage,
+            "package", dpackage,
-                                       "methods", sdesc.methods,
+            "methods", sdesc.methods,
-                                       "imports", imports.toList()));
+            "imports", imports.toList());
     }
 
     protected void generateProvider (File source, ServiceDescription sdesc)
@@ -584,13 +592,13 @@ public class GenServiceTask extends InvocationTask
         String mpath = source.getPath();
         mpath = mpath.replace("Service", "Provider");
         mpath = replacePath(mpath, "/client/", "/server/");
-        writeFile(mpath, mergeTemplate(PROVIDER_TMPL,
+        writeTemplate(PROVIDER_TMPL, mpath,
-                                       "name", name,
+            "name", name,
-                                       "generated", getGeneratedAnnotation(name),
+            "generated", getGeneratedAnnotation(name),
-                                       "package", mpackage,
+            "package", mpackage,
-                                       "methods", sdesc.methods,
+            "methods", sdesc.methods,
-                                       "listeners", sdesc.listeners,
+            "listeners", sdesc.listeners,
-                                       "imports", imports.toList()));
+            "imports", imports.toList());
     }
 
     /**
@@ -677,6 +685,9 @@ public class GenServiceTask extends InvocationTask
         }
     }
 
+    /** Show extra output if set. */
+    protected boolean _verbose;
+
     /** The path to our ActionScript source files. */
     protected File _asroot;
 

src/main/java/com/threerings/presents/tools/GenStreamableTask.java

@@ -28,7 +28,6 @@ import java.io.File;
 import java.io.IOException;
 
 import org.apache.tools.ant.DirectoryScanner;
-import org.apache.tools.ant.Task;
 import org.apache.tools.ant.types.FileSet;
 
 import com.google.common.collect.Lists;
@@ -42,13 +41,14 @@ import com.threerings.presents.dobj.DObject;
  * Streamable} classes that have protected or private members so that they can be used in a
  * sandboxed environment.
  */
-public class GenStreamableTask extends Task
+public class GenStreamableTask extends GenTask
 {
     /**
-     * Adds a nested <fileset> element which enumerates streamable source files.
+     * Adds a nested <fileset> element which enumerates streamable source
+     * files.
      */
-    public void addFileset (FileSet set)
+    @Override
-    {
+    public void addFileset(FileSet set) {
         _filesets.add(set);
     }
 
@@ -98,6 +98,7 @@ public class GenStreamableTask extends Task
     /**
      * Processes a resolved {@link Streamable} class instance.
      */
+    @Override
     protected void processClass (File source, Class<?> sclass)
         throws IOException
     {
@@ -156,11 +157,7 @@ public class GenStreamableTask extends Task
 
         System.err.println("Converting " + sclass.getName() + "...");
 
-        try {
+        writeFile(source.getAbsolutePath(), sfile.generate(null, methods.toString()));
-            sfile.writeTo(source, null, methods.toString());
-        } catch (IOException ioe) {
-            System.err.println("Error writing " + source + ": " + ioe);
-        }
     }
 
     protected String toReadObject (Field field)

src/main/java/com/threerings/presents/tools/GenTask.java

@@ -21,28 +21,35 @@
 
 package com.threerings.presents.tools;
 
-import java.util.List;
+import static com.google.common.base.Charsets.UTF_8;
-import java.util.Map;
 
 import java.io.File;
 import java.io.FileReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.io.PrintWriter;
+import java.io.Reader;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
 
 import org.apache.tools.ant.AntClassLoader;
 import org.apache.tools.ant.BuildException;
 import org.apache.tools.ant.DirectoryScanner;
+import org.apache.tools.ant.Project;
 import org.apache.tools.ant.Task;
 import org.apache.tools.ant.types.FileSet;
 import org.apache.tools.ant.types.Reference;
 import org.apache.tools.ant.util.ClasspathUtils;
 
-import com.google.common.collect.Maps;
 import com.google.common.collect.Lists;
-
+import com.google.common.collect.Maps;
+import com.google.common.collect.Sets;
+import com.google.common.io.Files;
 import com.samskivert.io.StreamUtil;
 import com.samskivert.mustache.Mustache;
 
+
 public abstract class GenTask extends Task
 {
     /**
@@ -53,14 +60,6 @@ public abstract class GenTask extends Task
         _filesets.add(set);
     }
 
-    /**
-     * Configures to output extra information when generating code.
-     */
-    public void setVerbose (boolean verbose)
-    {
-        _verbose = verbose;
-    }
-
     /**
      * Configures us with a header file that we'll prepend to all
      * generated source files.
@@ -86,12 +85,24 @@ public abstract class GenTask extends Task
         ((AntClassLoader)_cloader).setParent(getClass().getClassLoader());
     }
 
+    /**
+     * Fails the build if generation would change files rather than generating
+     * code.
+     */
+    public void setChecking (boolean checking)
+    {
+        _checking = checking;
+    }
+
     /**
      * Performs the actual work of the task.
      */
     @Override
     public void execute ()
     {
+        if (_checking) {
+            log("Only checking if generation would change files", Project.MSG_VERBOSE);
+        }
         for (FileSet fs : _filesets) {
             DirectoryScanner ds = fs.getDirectoryScanner(getProject());
             File fromDir = fs.getDir(getProject());
@@ -105,6 +116,47 @@ public abstract class GenTask extends Task
                 }
             }
         }
+        if (_checking && !_modifiedPaths.isEmpty()) {
+            throw new BuildException("Generation would produce changes!");
+        }
+
+    }
+
+    protected void writeTemplate (String templatePath, String outputPath, Object... data)
+        throws IOException
+    {
+        writeTemplate(templatePath, outputPath, createMap(data));
+    }
+
+    protected void writeTemplate (String templatePath, String outputPath, Map<String, Object> data)
+        throws IOException
+    {
+        String output = mergeTemplate(templatePath, data);
+        if (_header != null) {
+            output = _header + output;
+        }
+        writeFile(outputPath, output);
+    }
+
+    protected void writeFile (String outputPath, String output) throws IOException
+    {
+        File dest = new File(outputPath);
+        if (dest.exists()) {
+            if (Files.toString(dest, UTF_8).equals(output)) {
+                log("Skipping '" + outputPath + "' as it hasn't changed", Project.MSG_VERBOSE);
+                return;
+            }
+        } else if (!dest.getParentFile().exists() && !dest.getParentFile().mkdirs()) {
+            throw new BuildException("Unable to create directory for '" + dest.getAbsolutePath() + "'");
+        }
+        _modifiedPaths.add(outputPath);
+        if (_checking) {
+            log("Generating '" + outputPath + "' would have produced changes!", Project.MSG_ERR);
+            return;
+        }
+        log("Writing file " + outputPath, Project.MSG_VERBOSE);
+
+        new PrintWriter(dest, "UTF-8").append(output).close();
     }
 
     /**
@@ -114,13 +166,9 @@ public abstract class GenTask extends Task
      * be any object.
      */
     protected String mergeTemplate (String template, Object... data)
-        throws Exception
+        throws IOException
     {
-        Map<String, Object> ctx = Maps.newHashMap();
+        return mergeTemplate(template, createMap(data));
-        for (int ii = 0; ii < data.length; ii += 2) {
-            ctx.put((String)data[ii], data[ii+1]);
-        }
-        return mergeTemplate(template, ctx);
     }
 
     /**
@@ -129,10 +177,20 @@ public abstract class GenTask extends Task
      * @return a string containing the merged text.
      */
     protected String mergeTemplate (String template, Map<String, Object> data)
-        throws Exception
+        throws IOException
     {
-        return Mustache.compiler().escapeHTML(false).compile(new InputStreamReader(
+        Reader reader =
-            getClass().getClassLoader().getResourceAsStream(template), "UTF-8")).execute(data);
+            new InputStreamReader(getClass().getClassLoader().getResourceAsStream(template), UTF_8);
+        return Mustache.compiler().escapeHTML(false).compile(reader).execute(data);
+    }
+
+    protected Map<String, Object> createMap (Object... data)
+    {
+        Map<String, Object> ctx = Maps.newHashMap();
+        for (int ii = 0; ii < data.length; ii += 2) {
+            ctx.put((String)data[ii], data[ii+1]);
+        }
+        return ctx;
     }
 
     /**
@@ -172,12 +230,12 @@ public abstract class GenTask extends Task
     /** A list of filesets that contain java source to be processed. */
     protected List<FileSet> _filesets = Lists.newArrayList();
 
-    /** Show extra output if set. */
-    protected boolean _verbose;
-
     /** Used to do our own classpath business. */
     protected ClassLoader _cloader;
 
     /** A header to put on all generated source files. */
     protected String _header;
+
+    protected boolean _checking;
+    protected Set<String> _modifiedPaths = Sets.newHashSet();
 }

src/main/java/com/threerings/presents/tools/InvocationTask.java

@@ -31,10 +31,6 @@ import java.util.Arrays;
 import java.util.List;
 
 import java.io.File;
-import java.io.IOException;
-import java.io.PrintWriter;
-
-import org.apache.tools.ant.BuildException;
 import com.google.common.base.Predicate;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
@@ -395,22 +391,6 @@ public abstract class InvocationTask extends GenTask
         super.execute();
     }
 
-    protected void writeFile (String path, String data)
-        throws IOException
-    {
-        if (_verbose) {
-            System.out.println("Writing file " + path);
-        }
-        if (_header != null) {
-            data = _header + data;
-        }
-        File dest = new File(path);
-        if (!dest.getParentFile().exists() && !dest.getParentFile().mkdirs()) {
-            throw new BuildException("Unable to create directory for " + dest.getAbsolutePath());
-        }
-        new PrintWriter(dest, "UTF-8").append(data).close();
-    }
-
     protected static <T> void checkedAdd (List<T> list, T value)
     {
         if (!list.contains(value)) {

src/main/java/com/threerings/presents/tools/SourceFile.java

@@ -27,8 +27,8 @@ import java.io.BufferedReader;
 import java.io.BufferedWriter;
 import java.io.File;
 import java.io.FileReader;
-import java.io.FileWriter;
 import java.io.IOException;
+import java.io.StringWriter;
 
 import com.google.common.collect.Lists;
 
@@ -129,11 +129,11 @@ public class SourceFile
      * @param fsection the new "generated fields" to write to the file, or null.
      * @param msection the new "generated methods" to write to the file, or null.
      */
-    public void writeTo (File dest, String fsection, String msection)
+    public String generate (String fsection, String msection)
         throws IOException
     {
-        BufferedWriter bout = new BufferedWriter(new FileWriter(dest));
+        StringWriter writer = new StringWriter();
-
+        BufferedWriter bout = new BufferedWriter(writer);
         addOrRemoveGeneratedImport(StringUtil.deNull(fsection).contains("@Generated(") ||
             StringUtil.deNull(msection).contains("@Generated("));
 
@@ -180,6 +180,7 @@ public class SourceFile
             writeln(bout, _lines.get(ii));
         }
         bout.close();
+        return writer.toString();
     }
 
     /** Helper function for sanity checking marker existence. */

src/main/java/com/threerings/presents/tools/cpp/CPPUtil.java

@@ -6,19 +6,10 @@ import java.lang.reflect.TypeVariable;
 
 import java.util.Collections;
 import java.util.List;
-import java.util.Map;
-import java.io.BufferedWriter;
 import java.io.File;
-import java.io.FileWriter;
-import java.io.IOException;
-
-import com.google.common.base.Charsets;
 import com.google.common.base.Joiner;
 import com.google.common.base.Splitter;
 import com.google.common.collect.Lists;
-import com.google.common.io.Resources;
-import com.samskivert.mustache.Mustache;
-
 import com.threerings.presents.dobj.DSet;
 
 public class CPPUtil
@@ -70,19 +61,6 @@ public class CPPUtil
         }
     }
 
-    public static void writeTemplate (String tmplPath, File root, String path,
-        Map<String, Object> ctx)
-        throws IOException
-    {
-        String tmpl =
-            Resources.toString(Resources.getResource(tmplPath), Charsets.UTF_8);
-        File file = new File(root, path);
-        file.getParentFile().mkdirs();
-        BufferedWriter out = new BufferedWriter(new FileWriter(file));
-        Mustache.compiler().escapeHTML(false).compile(tmpl).execute(ctx, out);
-        out.close();
-    }
-
     public static String makeCPPName (Class<?> sclass)
     {
         return makeCPPName(makeNamespaces(sclass), sclass.getSimpleName());
@@ -103,6 +81,17 @@ public class CPPUtil
         return Joiner.on(File.separator).join(namespaces) + File.separator + className+ ext;
     }
 
+    public static String makePath (File root, Class<?> klass, String ext)
+    {
+        return new File(root, makePath(klass, ext)).getAbsolutePath();
+    }
+
+
+    public static String makePath (File root, List<String> namespaces, String className, String ext)
+    {
+        return new File(root, makePath(namespaces, className, ext)).getAbsolutePath();
+    }
+
     public static List<String> makeNamespaces (String pack)
     {
         Iterable<String> split = Splitter.on(".").split(pack);

src/main/java/com/threerings/presents/tools/cpp/GenCPPReceiverTask.java

@@ -1,5 +1,7 @@
 package com.threerings.presents.tools.cpp;
 
+import static com.threerings.presents.tools.cpp.CPPUtil.makePath;
+
 import java.lang.reflect.Type;
 
 import java.util.Iterator;
@@ -39,8 +41,7 @@ public class GenCPPReceiverTask extends GenReceiverTask
         ctx.put("receiverCode", rcode);
         ctx.put("argbuilder", new CPPArgBuilder(false));
 
-        CPPUtil.writeTemplate(DECODER_HEADER_TMPL, _cpproot,
+        writeTemplate(DECODER_HEADER_TMPL, makePath(_cpproot, namespaces, dname, ".h"), ctx);
-            CPPUtil.makePath(namespaces, dname, ".h"), ctx);
 
         Set<String> receiverHeaderIncludes = Sets.newTreeSet();
         Set<String> decoderImplIncludes = Sets.newTreeSet();
@@ -60,13 +61,9 @@ public class GenCPPReceiverTask extends GenReceiverTask
         }
 
         ctx.put("includes", decoderImplIncludes);
-        CPPUtil.writeTemplate(DECODER_CPP_TMPL, _cpproot,
+        writeTemplate(DECODER_CPP_TMPL, makePath(_cpproot, namespaces, dname, ".cpp"), ctx);
-            CPPUtil.makePath(namespaces, dname, ".cpp"), ctx);
-
-
         ctx.put("includes", receiverHeaderIncludes);
-        CPPUtil.writeTemplate(RECEIVER_HEADER_TMPL, _cpproot,
+        writeTemplate(RECEIVER_HEADER_TMPL, makePath(_cpproot, namespaces, rname, ".h"), ctx);
-            CPPUtil.makePath(namespaces, rname, ".h"), ctx);
 
         super.generateDecoder(receiver, source, rname, rpackage, methods, imports, rcode);
     }

src/main/java/com/threerings/presents/tools/cpp/GenCPPServiceTask.java

@@ -15,7 +15,6 @@ import com.threerings.presents.tools.GenServiceTask;
 
 import static com.threerings.presents.tools.cpp.CPPUtil.makeNamespaces;
 import static com.threerings.presents.tools.cpp.CPPUtil.makePath;
-import static com.threerings.presents.tools.cpp.CPPUtil.writeTemplate;
 
 public class GenCPPServiceTask extends GenServiceTask
 {
@@ -58,9 +57,9 @@ public class GenCPPServiceTask extends GenServiceTask
             }
         }
         ctx.put("includes", implIncludes);
-        writeTemplate(CPP_TMPL, _cpproot, makePath(namespaces, name, ".cpp"), ctx);
+        writeTemplate(CPP_TMPL, makePath(_cpproot, namespaces, name, ".cpp"), ctx);
         ctx.put("includes", includes);
-        writeTemplate(HEADER_TMPL, _cpproot, makePath(namespaces, name, ".h"), ctx);
+        writeTemplate(HEADER_TMPL, makePath(_cpproot, namespaces, name, ".h"), ctx);
         super.generateMarshaller(source, sdesc);
     }
 

src/main/java/com/threerings/presents/tools/cpp/GenCPPStreamableTask.java

@@ -134,10 +134,10 @@ public class GenCPPStreamableTask extends GenTask
 
         // now write all that out to the target source file
         ctx.put("includes", headerIncludes);
-        CPPUtil.writeTemplate(HEADER_TMPL, _cpproot, makePath(sclass, ".h"), ctx);
+        writeTemplate(HEADER_TMPL, makePath(_cpproot, sclass, ".h"), ctx);
 
         ctx.put("includes", implIncludes);
-        CPPUtil.writeTemplate(CPP_TMPL, _cpproot, makePath(sclass, ".cpp"), ctx);
+        writeTemplate(CPP_TMPL, makePath(_cpproot, sclass, ".cpp"), ctx);
     }
 
     protected static void addInclude (Class<?> ftype, Set<String> includes)