Make EvalTask track resolved output paths and fix file() notation on Gradle on Windows (#403)

* Add `getEffectiveOutputFiles` and `getEffectiveOutputDirs` to `EvalTask`, and mark them as output files/dirs so they are tracked by Gradle. This enables implicit dependency tracking between two tasks.
* Fix usage of `file()` notation in Gradle scripts when on Windows.

pkl-cli/src/main/kotlin/org/pkl/cli/CliEvaluator.kt

@@ -51,9 +51,10 @@ constructor(
   private val consoleWriter: Writer = System.out.writer(),
 ) : CliCommand(options.base) {
   /**
-   * Output files for the modules to be evaluated. Returns `null` if `options.outputPath` is `null`.
-   * Multiple modules may be mapped to the same output file, in which case their outputs are
-   * concatenated with [CliEvaluatorOptions.moduleOutputSeparator].
+   * Output files for the modules to be evaluated. Returns `null` if `options.outputPath` is `null`
+   * or if `options.multipleFileOutputPath` is not `null`. Multiple modules may be mapped to the
+   * same output file, in which case their outputs are concatenated with
+   * [CliEvaluatorOptions.moduleOutputSeparator].
    */
   @Suppress("MemberVisibilityCanBePrivate")
   val outputFiles: Set<File>? by lazy {

pkl-gradle/src/main/java/org/pkl/gradle/task/BasePklTask.java

@@ -28,15 +28,18 @@ import java.util.List;
 import java.util.function.Function;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
+import javax.inject.Inject;
 import org.gradle.api.DefaultTask;
 import org.gradle.api.InvalidUserDataException;
 import org.gradle.api.file.ConfigurableFileCollection;
 import org.gradle.api.file.DirectoryProperty;
 import org.gradle.api.file.FileSystemLocation;
+import org.gradle.api.model.ObjectFactory;
 import org.gradle.api.provider.ListProperty;
 import org.gradle.api.provider.MapProperty;
 import org.gradle.api.provider.Property;
 import org.gradle.api.provider.Provider;
+import org.gradle.api.provider.ProviderFactory;
 import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.InputFile;
 import org.gradle.api.tasks.InputFiles;
@@ -142,6 +145,7 @@ public abstract class BasePklTask extends DefaultTask {
 
   @LateInit protected CliBaseOptions cachedOptions;
 
+  // Must be called during task execution time only.
   @Internal
   protected CliBaseOptions getCliBaseOptions() {
     if (cachedOptions == null) {
@@ -176,6 +180,12 @@ public abstract class BasePklTask extends DefaultTask {
     return Collections.emptyList();
   }
 
+  @Inject
+  protected abstract ObjectFactory getObjects();
+
+  @Inject
+  protected abstract ProviderFactory getProviders();
+
   protected List<Path> parseModulePath() {
     return getModulePath().getFiles().stream().map(File::toPath).collect(Collectors.toList());
   }

pkl-gradle/src/main/java/org/pkl/gradle/task/EvalTask.java

@@ -16,50 +16,82 @@
 package org.pkl.gradle.task;
 
 import java.io.File;
+import java.util.Collections;
+import java.util.Set;
+import javax.annotation.Nullable;
 import org.gradle.api.file.DirectoryProperty;
+import org.gradle.api.file.FileCollection;
 import org.gradle.api.file.RegularFileProperty;
 import org.gradle.api.provider.Property;
+import org.gradle.api.provider.Provider;
 import org.gradle.api.tasks.Input;
+import org.gradle.api.tasks.Internal;
 import org.gradle.api.tasks.Optional;
-import org.gradle.api.tasks.OutputDirectory;
-import org.gradle.api.tasks.OutputFile;
+import org.gradle.api.tasks.OutputDirectories;
+import org.gradle.api.tasks.OutputFiles;
 import org.pkl.cli.CliEvaluator;
 import org.pkl.cli.CliEvaluatorOptions;
 
 public abstract class EvalTask extends ModulesTask {
-  @OutputFile
-  @Optional
+
+  // not tracked because it might contain placeholders
+  // required
+  @Internal
   public abstract RegularFileProperty getOutputFile();
 
-  @Input
-  @Optional
-  public abstract Property<String> getOutputFormat();
-
-  @Input
-  @Optional
-  public abstract Property<String> getModuleOutputSeparator();
-
-  @OutputDirectory
-  @Optional
+  // not tracked because it might contain placeholders
+  // optional
+  @Internal
   public abstract DirectoryProperty getMultipleFileOutputDir();
 
   @Input
-  @Optional
+  public abstract Property<String> getOutputFormat();
+
+  @Input
+  public abstract Property<String> getModuleOutputSeparator();
+
+  @Input
   public abstract Property<String> getExpression();
 
+  private final Provider<CliEvaluator> cliEvaluator =
+      getProviders()
+          .provider(
+              () ->
+                  new CliEvaluator(
+                      new CliEvaluatorOptions(
+                          getCliBaseOptions(),
+                          getOutputFile().get().getAsFile().getAbsolutePath(),
+                          getOutputFormat().get(),
+                          getModuleOutputSeparator().get(),
+                          mapAndGetOrNull(
+                              getMultipleFileOutputDir(), it -> it.getAsFile().getAbsolutePath()),
+                          getExpression().get())));
+
+  @SuppressWarnings("unused")
+  @OutputFiles
+  @Optional
+  public FileCollection getEffectiveOutputFiles() {
+    return getObjects()
+        .fileCollection()
+        .from(cliEvaluator.map(e -> nullToEmpty(e.getOutputFiles())));
+  }
+
+  @OutputDirectories
+  @Optional
+  public FileCollection getEffectiveOutputDirs() {
+    return getObjects()
+        .fileCollection()
+        .from(cliEvaluator.map(e -> nullToEmpty(e.getOutputDirectories())));
+  }
+
+  private static <T> Set<T> nullToEmpty(@Nullable Set<T> set) {
+    return set == null ? Collections.emptySet() : set;
+  }
+
   @Override
   protected void doRunTask() {
     //noinspection ResultOfMethodCallIgnored
     getOutputs().getPreviousOutputFiles().forEach(File::delete);
-
-    new CliEvaluator(
-            new CliEvaluatorOptions(
-                getCliBaseOptions(),
-                getOutputFile().get().getAsFile().getAbsolutePath(),
-                getOutputFormat().get(),
-                getModuleOutputSeparator().get(),
-                mapAndGetOrNull(getMultipleFileOutputDir(), it -> it.getAsFile().getAbsolutePath()),
-                getExpression().get()))
-        .run();
+    cliEvaluator.get().run();
   }
 }

pkl-gradle/src/main/java/org/pkl/gradle/task/ModulesTask.java

@@ -128,12 +128,15 @@ public abstract class ModulesTask extends BasePklTask {
   }
 
   /**
-   * Converts either a file or a URI to a URI. We convert a file to a URI via the {@link
+   * Converts either a file or a URI to a URI. We convert a relative file to a URI via the {@link
    * IoUtils#createUri(String)} because other ways of conversion can make relative paths into
    * absolute URIs, which may break module loading.
    */
   private URI parsedModuleNotationToUri(Object notation) {
     if (notation instanceof File file) {
+      if (file.isAbsolute()) {
+        return file.toPath().toUri();
+      }
       return IoUtils.createUri(IoUtils.toNormalizedPathString(file.toPath()));
     } else if (notation instanceof URI uri) {
       return uri;

pkl-gradle/src/test/kotlin/org/pkl/gradle/EvaluatorsTest.kt

@@ -16,7 +16,9 @@
 package org.pkl.gradle
 
 import java.nio.file.Path
+import kotlin.io.path.readText
 import org.assertj.core.api.Assertions.assertThat
+import org.gradle.testkit.runner.TaskOutcome
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.io.TempDir
 import org.pkl.commons.readString
@@ -549,12 +551,301 @@ class EvaluatorsTest : AbstractTest() {
     assertThat(testProjectDir.resolve("proj1/foo.pcf")).exists()
   }
 
+  @Test
+  fun `implicit dependency tracking for effective output files`() {
+    writeFile("file1.pkl", "foo = 1")
+
+    writeFile("file2.pkl", "bar = 1")
+
+    writeFile(
+      "build.gradle.kts",
+      """
+      import org.pkl.gradle.task.EvalTask
+
+      plugins {
+        id("org.pkl-lang")
+      }
+
+      pkl {
+        evaluators {
+          register("doEval") {
+            sourceModules = files("file1.pkl", "file2.pkl")
+            outputFile = layout.projectDirectory.file("%{moduleName}.%{outputFormat}")
+            outputFormat = "yaml"
+          }
+        }
+      }
+
+      val doEval by tasks.existing(EvalTask::class) {
+        doLast {
+          file("evalCounter.txt").appendText("doEval executed\n")
+        }
+      }
+
+      val printEvalFiles by tasks.registering {
+        inputs.files(doEval)
+        doLast {
+          println("evalCounter.txt")
+          println(file("evalCounter.txt").readText())
+          
+          inputs.files.forEach {
+            println(it.name)
+            println(it.readText())
+          }
+        }
+      }
+    """
+        .trimIndent()
+    )
+
+    val result1 = runTask("printEvalFiles")
+
+    // `doEval` task is invoked transitively.
+    assertThat(result1.task(":doEval")?.outcome).isEqualTo(TaskOutcome.SUCCESS)
+
+    assertThat(result1.output)
+      .containsIgnoringNewLines(
+        """
+      evalCounter.txt
+      doEval executed
+      
+      file1.yaml
+      foo: 1
+
+      file2.yaml
+      bar: 1
+      """
+          .trimIndent()
+      )
+
+    // Run the task again to check that it is cached.
+    val result2 = runTask("printEvalFiles")
+
+    assertThat(result2.task(":doEval")?.outcome).isEqualTo(TaskOutcome.UP_TO_DATE)
+
+    // evalCounter.txt content is the same as before.
+    assertThat(result2.output)
+      .containsIgnoringNewLines(
+        """
+      evalCounter.txt
+      doEval executed
+      
+      file1.yaml
+      foo: 1
+
+      file2.yaml
+      bar: 1
+      """
+          .trimIndent()
+      )
+
+    // Modify the input file.
+    writeFile("file1.pkl", "foo = 7")
+
+    // Run the build again - the evaluation task will not be cached.
+    val result3 = runTask("printEvalFiles")
+
+    assertThat(result3.task(":doEval")?.outcome).isEqualTo(TaskOutcome.SUCCESS)
+
+    // evalCounter.txt content is updated too.
+    assertThat(result3.output)
+      .containsIgnoringNewLines(
+        """
+      evalCounter.txt
+      doEval executed
+      doEval executed
+      
+      file1.yaml
+      foo: 7
+
+      file2.yaml
+      bar: 1
+      """
+          .trimIndent()
+      )
+  }
+
+  @Test
+  fun `implicit dependency tracking for multiple output directory`() {
+    writePklFile(
+      """
+      pigeon {
+        name = "Pigeon"
+        diet = "Seeds"
+      }
+      
+      parrot {
+        name = "Parrot"
+        diet = "Seeds"
+      }
+      
+      output {
+        files {
+          ["birds/pigeon.json"] {
+            value = pigeon
+            renderer = new JsonRenderer {}
+          }
+          ["birds/parrot.pcf"] {
+            value = parrot
+            renderer = new PcfRenderer {}
+          }
+        }
+      }
+    """
+        .trimIndent()
+    )
+
+    writeBuildFile(
+      "yaml",
+      additionalContents =
+        """
+        multipleFileOutputDir = layout.projectDirectory.dir("%{moduleDir}/%{moduleName}-%{outputFormat}")
+      """
+          .trimIndent(),
+      additionalBuildScript =
+        """
+        tasks.named('evalTest') {
+          doLast {
+            file("evalCounter.txt").append("evalTest executed\n")
+          }
+        }
+        
+        abstract class PrintTask extends DefaultTask {
+          @InputFiles
+          public abstract ConfigurableFileCollection getInputDirs();
+        }
+        
+        // ensure that iteration order is the same across environments
+        def sortByTypeThenName = { a, b ->
+            a.isFile() != b.isFile() ? a.isFile() <=> b.isFile() : a.name <=> b.name
+        }
+
+        tasks.register('printEvalDirs', PrintTask) {
+          inputDirs.from(tasks.named('evalTest'))
+          
+          doLast {
+            println "evalCounter.txt"
+            println file("evalCounter.txt").text
+
+            inputDirs.forEach { f ->
+              f.traverse(visitRoot: true, sort: sortByTypeThenName) {
+                if (it.isDirectory()) {
+                  println layout.projectDirectory.asFile.relativePath(it) + '/'
+                  println()
+                } else {
+                  println layout.projectDirectory.asFile.relativePath(it)
+                  println it.text
+                }
+              }
+            }
+          }
+        }
+      """
+          .trimIndent()
+    )
+
+    val result1 = runTask("printEvalDirs")
+
+    // `doEval` task is invoked transitively.
+    assertThat(result1.task(":evalTest")?.outcome).isEqualTo(TaskOutcome.SUCCESS)
+
+    // NB: Configured output format, 'yaml', is only used to replace the placeholder in the path;
+    // the output files themselves are formatted according to configuration
+    // in the rendered module.
+
+    assertThat(result1.output)
+      .containsIgnoringNewLines(
+        """
+      evalCounter.txt
+      evalTest executed
+      
+      test-yaml/birds/
+      
+      test-yaml/birds/parrot.pcf
+      name = "Parrot"
+      diet = "Seeds"
+      
+      test-yaml/birds/pigeon.json
+      {
+        "name": "Pigeon",
+        "diet": "Seeds"
+      }
+      
+      test-yaml/
+      """
+          .trimIndent()
+      )
+
+    // Run the task again to check that it is cached.
+    val result2 = runTask("printEvalDirs")
+
+    assertThat(result2.task(":evalTest")?.outcome).isEqualTo(TaskOutcome.UP_TO_DATE)
+
+    // evalCounter.txt content is the same as before.
+    assertThat(result2.output)
+      .containsIgnoringNewLines(
+        """
+      evalCounter.txt
+      evalTest executed
+      
+      test-yaml/birds/
+      
+      test-yaml/birds/parrot.pcf
+      name = "Parrot"
+      diet = "Seeds"
+      
+      test-yaml/birds/pigeon.json
+      {
+        "name": "Pigeon",
+        "diet": "Seeds"
+      }
+      
+      test-yaml/
+      """
+          .trimIndent()
+      )
+
+    // Modify the input file.
+    writePklFile(testProjectDir.resolve("test.pkl").readText().replace("Parrot", "Macaw"))
+
+    // Run the build again - the evaluation task will not be cached.
+    val result3 = runTask("printEvalDirs")
+
+    assertThat(result3.task(":evalTest")?.outcome).isEqualTo(TaskOutcome.SUCCESS)
+
+    // evalCounter.txt content is updated too.
+    assertThat(result3.output)
+      .containsIgnoringNewLines(
+        """
+      evalCounter.txt
+      evalTest executed
+      evalTest executed
+      
+      test-yaml/birds/
+      
+      test-yaml/birds/parrot.pcf
+      name = "Macaw"
+      diet = "Seeds"
+      
+      test-yaml/birds/pigeon.json
+      {
+        "name": "Pigeon",
+        "diet": "Seeds"
+      }
+      
+      test-yaml/
+      """
+          .trimIndent()
+      )
+  }
+
   private fun writeBuildFile(
     // don't use `org.pkl.core.OutputFormat`
     // because test compile class path doesn't contain pkl-core
     outputFormat: String,
     additionalContents: String = "",
-    sourceModules: List<String> = listOf("test.pkl")
+    sourceModules: List<String> = listOf("test.pkl"),
+    additionalBuildScript: String = ""
   ) {
     writeFile(
       "build.gradle",
@@ -573,6 +864,8 @@ class EvaluatorsTest : AbstractTest() {
           }
         }
       }
+      
+      $additionalBuildScript
     """
     )
   }