feat: adds `replSource` property and command-line option

The `replSource` property specifies the frege source file that you want to
load into the repl. It is excluded in the `fregeCompile` task so that
we don't get two java class files (one from `compileFrege` and one
from the fregeRepl `:l` command) that shadow each other on the classpath.

As a result, we can make interactive changes to the `replSource` file and
use the `:r` reload command to see them.

6 files changed, 108 insertions, 19 deletions

diff --git a/src/main/java/ch/fhnw/thga/gradleplugins/CompileFregeTask.java b/src/main/java/ch/fhnw/thga/gradleplugins/CompileFregeTask.java
index e81fe76..32ce798 100644
--- a/src/main/java/ch/fhnw/thga/gradleplugins/CompileFregeTask.java
+++ b/src/main/java/ch/fhnw/thga/gradleplugins/CompileFregeTask.java
@@ -3,13 +3,16 @@ package ch.fhnw.thga.gradleplugins;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
+import java.util.function.BiFunction;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 import javax.inject.Inject;
 
 import org.gradle.api.DefaultTask;
+import org.gradle.api.file.Directory;
 import org.gradle.api.file.DirectoryProperty;
+import org.gradle.api.file.FileTree;
 import org.gradle.api.file.RegularFileProperty;
 import org.gradle.api.model.ObjectFactory;
 import org.gradle.api.provider.ListProperty;
@@ -29,6 +32,22 @@ import org.gradle.api.tasks.TaskAction;
 @CacheableTask
 public abstract class CompileFregeTask extends DefaultTask {
     private final JavaExec javaExec;
+    private static final BiFunction<String, Directory, FileTree> excludeReplSourceFile =
+        (String replSource,
+        Directory srcDir) ->
+    {
+        if (replSource.isEmpty()) return srcDir.getAsFileTree();
+        return srcDir.getAsFileTree().matching(
+            pattern ->
+            {
+                pattern.exclude(
+                    String.format(
+                    "**/%s",
+                    replSource)
+                );
+            }
+        );
+    };
 
     @InputFile
     @PathSensitive(PathSensitivity.RELATIVE)
@@ -44,6 +63,9 @@ public abstract class CompileFregeTask extends DefaultTask {
     @Input
     public abstract Property<String> getFregeDependencies();
 
+    @Input
+    public abstract Property<String> getReplSource();
+
     @OutputDirectory
     public abstract DirectoryProperty getFregeOutputDir();
 
@@ -58,9 +80,26 @@ public abstract class CompileFregeTask extends DefaultTask {
     }
 
     @Internal
+    public final Provider<FileTree> getSourceFileTree() {
+        return getReplSource().zip(
+            getFregeMainSourceDir(),
+            excludeReplSourceFile);
+    }
+
+    @Internal
+    public final Provider<List<String>> getSourceFiles() {
+        return getSourceFileTree()
+            .map(tree -> tree.getFiles().stream()
+            .map(file -> file.getAbsolutePath())
+            .collect(Collectors.toList())
+        );
+    }
+
+    @Internal
     public final Provider<List<String>> getDependencyArg() {
         return getFregeDependencies().map(depsClasspath -> {
-            return depsClasspath.isEmpty() ? Collections.emptyList() : List.of("-fp", depsClasspath);
+            return depsClasspath.isEmpty() ? Collections.emptyList()
+                                           : List.of("-fp", depsClasspath);
         });
     }
 
@@ -69,16 +108,25 @@ public abstract class CompileFregeTask extends DefaultTask {
         javaExec = objectFactory.newInstance(JavaExec.class);
     }
 
-    private List<String> buildCompilerArgsFromProperties(List<String> directoryArg) {
-        return Stream
-                .of(getDependencyArg().get(), getFregeCompilerFlags().get(), directoryArg, getSourcePathArg().get(),
-                        List.of(getFregeMainSourcePath().get()))
-                .filter(lists -> !lists.isEmpty()).flatMap(Collection::stream).collect(Collectors.toList());
+    private List<String> buildCompilerArgsFromProperties(List<String> directoryArg)
+    {
+        return Stream.of(
+            getDependencyArg().get(),
+            getFregeCompilerFlags().get(),
+            directoryArg,
+            getSourcePathArg().get(),
+            getSourceFiles().get())
+        .filter(lists -> !lists.isEmpty())
+        .flatMap(Collection::stream)
+        .collect(Collectors.toList());
     }
 
     @TaskAction
     public void compileFrege() {
-        List<String> directoryArg = List.of("-d", getFregeOutputDir().getAsFile().get().getAbsolutePath());
+        List<String> directoryArg = List.of(
+            "-d",
+            getFregeOutputDir().getAsFile().get().getAbsolutePath());
+
         javaExec.setClasspath(getProject().files(getFregeCompilerJar()))
                 .setArgs(buildCompilerArgsFromProperties(directoryArg)).exec();
     }
diff --git a/src/main/java/ch/fhnw/thga/gradleplugins/FregeExtension.java b/src/main/java/ch/fhnw/thga/gradleplugins/FregeExtension.java
index ea02493..7b186a8 100644
--- a/src/main/java/ch/fhnw/thga/gradleplugins/FregeExtension.java
+++ b/src/main/java/ch/fhnw/thga/gradleplugins/FregeExtension.java
@@ -10,9 +10,9 @@ import org.gradle.api.provider.ListProperty;
 import org.gradle.api.provider.Property;
 
 public abstract class FregeExtension {
-    public static final String DEFAULT_DOWNLOAD_DIRECTORY = "lib";
-    public static final String DEFAULT_RELATIVE_OUTPUT_DIR = "classes/main/frege";
-    public static final String DEFAULT_RELATIVE_SOURCE_DIR = "src/main/frege";
+    public static final String DEFAULT_DOWNLOAD_DIRECTORY   = "lib";
+    public static final String DEFAULT_RELATIVE_OUTPUT_DIR  = "classes/main/frege";
+    public static final String DEFAULT_RELATIVE_SOURCE_DIR  = "src/main/frege";
     public static final List<String> DEFAULT_COMPILER_FLAGS = List.of("-O", "-make");
 
     public abstract Property<String> getVersion();
@@ -29,11 +29,19 @@ public abstract class FregeExtension {
 
     public abstract ListProperty<String> getCompilerFlags();
 
+    public abstract Property<String> getReplModule();
+
     @Inject
     public FregeExtension(ProjectLayout projectLayout) {
-        getCompilerDownloadDir().convention(projectLayout.getProjectDirectory().dir(DEFAULT_DOWNLOAD_DIRECTORY));
-        getMainSourceDir().convention(projectLayout.getProjectDirectory().dir(DEFAULT_RELATIVE_SOURCE_DIR));
-        getOutputDir().convention(projectLayout.getBuildDirectory().dir(DEFAULT_RELATIVE_OUTPUT_DIR));
+        getCompilerDownloadDir()
+        .convention(projectLayout.getProjectDirectory().dir(DEFAULT_DOWNLOAD_DIRECTORY));
+
+        getMainSourceDir()
+        .convention(projectLayout.getProjectDirectory().dir(DEFAULT_RELATIVE_SOURCE_DIR));
+
+        getOutputDir()
+        .convention(projectLayout.getBuildDirectory().dir(DEFAULT_RELATIVE_OUTPUT_DIR));
+
         getCompilerFlags().convention(DEFAULT_COMPILER_FLAGS);
     }
 }
diff --git a/src/main/java/ch/fhnw/thga/gradleplugins/FregePlugin.java b/src/main/java/ch/fhnw/thga/gradleplugins/FregePlugin.java
index e00b297..26c52c8 100644
--- a/src/main/java/ch/fhnw/thga/gradleplugins/FregePlugin.java
+++ b/src/main/java/ch/fhnw/thga/gradleplugins/FregePlugin.java
@@ -20,8 +20,13 @@ public class FregePlugin implements Plugin<Project>
 
     @Override
     public void apply(Project project) {
-        Configuration implementation = project.getConfigurations().create(FREGE_IMPLEMENTATION_SCOPE);
-        FregeExtension extension     = project.getExtensions().create(
+        Configuration implementation = project
+                                       .getConfigurations()
+                                       .create(FREGE_IMPLEMENTATION_SCOPE);
+
+        FregeExtension extension     = project
+                                       .getExtensions()
+                                       .create(
                                        FREGE_EXTENSION_NAME,
                                        FregeExtension.class);
 
@@ -36,7 +41,7 @@ public class FregePlugin implements Plugin<Project>
                     task.getDownloadDir().set(extension.getCompilerDownloadDir());
                 });
 
-        TaskProvider<CompileFregeTask> compileFregeTask     =
+        TaskProvider<CompileFregeTask> compileFregeTask =
             project.getTasks().register(
                 COMPILE_FREGE_TASK_NAME,
                 CompileFregeTask.class,
@@ -49,6 +54,7 @@ public class FregePlugin implements Plugin<Project>
                     task.getFregeOutputDir().set(extension.getOutputDir());
                     task.getFregeCompilerFlags().set(extension.getCompilerFlags());
                     task.getFregeDependencies().set(implementation.getAsPath());
+                    task.getReplSource().set("");
                 }
             );
 
@@ -71,6 +77,13 @@ public class FregePlugin implements Plugin<Project>
             DependencyFregeTask.class,
             task ->
             {
+                task.dependsOn(compileFregeTask.map(
+                    compileTask ->
+                    {
+                        compileTask.getReplSource().set(task.getReplSource());
+                        return compileTask;
+                    })
+                .get());
                 task.dependsOn(compileFregeTask);
                 task.getFregeCompilerJar().set(
                     setupFregeCompilerTask.get().getFregeCompilerOutputPath());
@@ -84,7 +97,14 @@ public class FregePlugin implements Plugin<Project>
             ReplFregeTask.class,
             task ->
             {
-                task.dependsOn(compileFregeTask);
+                task.getReplSource().set(extension.getReplModule());
+                task.dependsOn(compileFregeTask.map(
+                    compileTask ->
+                    {
+                        compileTask.getReplSource().set(task.getReplSource());
+                        return compileTask;
+                    })
+                .get());
                 task.getFregeCompilerJar().set(
                     setupFregeCompilerTask.get().getFregeCompilerOutputPath());
                 task.getFregeOutputDir().set(extension.getOutputDir());
diff --git a/src/main/java/ch/fhnw/thga/gradleplugins/ReplFregeTask.java b/src/main/java/ch/fhnw/thga/gradleplugins/ReplFregeTask.java
index 475946b..dd18270 100644
--- a/src/main/java/ch/fhnw/thga/gradleplugins/ReplFregeTask.java
+++ b/src/main/java/ch/fhnw/thga/gradleplugins/ReplFregeTask.java
@@ -8,6 +8,7 @@ import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.InputDirectory;
 import org.gradle.api.tasks.InputFile;
 import org.gradle.api.tasks.TaskAction;
+import org.gradle.api.tasks.options.Option;
 
 public abstract class ReplFregeTask extends DefaultTask {
     public static final String REPL_MAIN_CLASS = "frege.repl.FregeRepl";
@@ -21,6 +22,11 @@ public abstract class ReplFregeTask extends DefaultTask {
     @InputDirectory
     public abstract DirectoryProperty getFregeOutputDir();
 
+    @Input
+    @Option(option     = "replSource",
+           description = "The filename which you want to load into the repl, e.g. 'myFregeFile.fr'")
+    public abstract Property<String> getReplSource();
+
     @TaskAction
     public void printStartFregeReplCommand() {
         System.out.println("Execute the following command to start the Frege Repl:");
diff --git a/src/main/java/ch/fhnw/thga/gradleplugins/SetupFregeTask.java b/src/main/java/ch/fhnw/thga/gradleplugins/SetupFregeTask.java
index 1b12f56..6bfe72d 100644
--- a/src/main/java/ch/fhnw/thga/gradleplugins/SetupFregeTask.java
+++ b/src/main/java/ch/fhnw/thga/gradleplugins/SetupFregeTask.java
@@ -21,9 +21,10 @@ import org.gradle.api.tasks.OutputFile;
 import org.gradle.api.tasks.TaskAction;
 
 public abstract class SetupFregeTask extends DefaultTask {
-    public static final Logger LOGGER = Logging.getLogger(SetupFregeTask.class);
+    public static final Logger LOGGER                   = Logging.getLogger(SetupFregeTask.class);
 
-    private static final String FREGE_GITHUB_URL_PREFIX = "https://github.com/Frege/frege/releases/download";
+    private static final String FREGE_GITHUB_URL_PREFIX =
+                                               "https://github.com/Frege/frege/releases/download";
 
     @Input
     public abstract Property<String> getVersion();
diff --git a/src/main/java/ch/fhnw/thga/gradleplugins/internal/DependencyFregeTask.java b/src/main/java/ch/fhnw/thga/gradleplugins/internal/DependencyFregeTask.java
index 4459bd4..87f4d2b 100644
--- a/src/main/java/ch/fhnw/thga/gradleplugins/internal/DependencyFregeTask.java
+++ b/src/main/java/ch/fhnw/thga/gradleplugins/internal/DependencyFregeTask.java
@@ -8,6 +8,7 @@ import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.InputDirectory;
 import org.gradle.api.tasks.InputFile;
 import org.gradle.api.tasks.TaskAction;
+import org.gradle.api.tasks.options.Option;
 
 import ch.fhnw.thga.gradleplugins.SharedTaskLogic;
 
@@ -21,6 +22,11 @@ public abstract class DependencyFregeTask extends DefaultTask {
     @InputDirectory
     public abstract DirectoryProperty getFregeOutputDir();
 
+    @Input
+    @Option(option     = "replSource",
+           description = "The filename which you want to load into the repl, e.g. 'myFregeFile.fr'")
+    public abstract Property<String> getReplSource();
+
 
     @TaskAction
     public void fregeDependencies() {