proof-of-concept: ideally we'd leverage palantir/palantir-java-format…

…#562

goethe/src/main/java/com/palantir/goethe/BootstrappingFormatterFacade.java

@@ -0,0 +1,86 @@
+/*
+ * (c) Copyright 2021 Palantir Technologies Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.palantir.goethe;
+
+import com.google.common.io.ByteStreams;
+import com.palantir.javaformat.java.Main;
+import com.squareup.javapoet.JavaFile;
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
+
+final class BootstrappingFormatterFacade implements FormatterFacade {
+
+    @Override
+    public String formatSource(JavaFile file) throws GoetheException {
+        try {
+            Process process = new ProcessBuilder(
+                            new File(System.getProperty("java.home"), "bin/java").getAbsolutePath(),
+                            // Exports
+                            "--add-exports",
+                            "jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED",
+                            "--add-exports",
+                            "jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED",
+                            "--add-exports",
+                            "jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED",
+                            "--add-exports",
+                            "jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED",
+                            "--add-exports",
+                            "jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED",
+                            // Classpath
+                            "-cp",
+                            System.getProperty("java.class.path"),
+                            // Main class
+                            Main.class.getName(),
+                            // Args
+                            "--palantir",
+                            "--skip-reflowing-long-strings",
+                            "-")
+                    .start();
+            StringBuilder rawSource = new StringBuilder();
+            file.writeTo(rawSource);
+            try (OutputStream outputStream = process.getOutputStream()) {
+                outputStream.write(rawSource.toString().getBytes(StandardCharsets.UTF_8));
+            }
+            byte[] data;
+            try (InputStream inputStream = process.getInputStream()) {
+                data = ByteStreams.toByteArray(inputStream);
+            }
+            int exitStatus = process.waitFor();
+            if (exitStatus != 0) {
+                throw new GoetheException("Bootstrapped formatter exited non-zero: " + exitStatus + " with output:\n"
+                        + getErrorOutput(process));
+            }
+            return new String(data, StandardCharsets.UTF_8);
+        } catch (IOException | InterruptedException e) {
+            throw new GoetheException("Failed to bootstrap jdk", e);
+        }
+    }
+
+    private static String getErrorOutput(Process process) {
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        try (InputStream inputStream = process.getErrorStream()) {
+            ByteStreams.copy(inputStream, baos);
+        } catch (IOException | RuntimeException ignored) {
+            // continue
+        }
+        return baos.toString(StandardCharsets.UTF_8);
+    }
+}

goethe/src/main/java/com/palantir/goethe/DirectFormatterFacade.java

@@ -0,0 +1,81 @@
+/*
+ * (c) Copyright 2021 Palantir Technologies Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.palantir.goethe;
+
+import com.google.common.base.CharMatcher;
+import com.google.common.base.Splitter;
+import com.google.common.base.Strings;
+import com.palantir.javaformat.java.Formatter;
+import com.palantir.javaformat.java.FormatterDiagnostic;
+import com.palantir.javaformat.java.FormatterException;
+import com.palantir.javaformat.java.JavaFormatterOptions;
+import com.squareup.javapoet.JavaFile;
+import java.io.IOException;
+import java.util.List;
+
+final class DirectFormatterFacade implements FormatterFacade {
+
+    private final Formatter formatter = Formatter.createFormatter(JavaFormatterOptions.builder()
+            .style(JavaFormatterOptions.Style.PALANTIR)
+            .build());
+
+    @Override
+    public String formatSource(JavaFile file) throws GoetheException {
+        StringBuilder rawSource = new StringBuilder();
+        try {
+            file.writeTo(rawSource);
+            return formatter.formatSource(rawSource.toString());
+        } catch (FormatterException e) {
+            throw new GoetheException(generateMessage(file, rawSource.toString(), e.diagnostics()), e);
+        } catch (IOException e) {
+            throw new GoetheException("Formatting failed", e);
+        }
+    }
+
+    /**
+     * Attempt to provide as much actionable information as possible to understand why formatting is failing. This
+     * is common when generated code is incorrect and cannot compile, so we mustn't make it difficult to understand
+     * the problem.
+     */
+    private static String generateMessage(
+            JavaFile file, String unformattedSource, List<FormatterDiagnostic> formatterDiagnostics) {
+        try {
+            List<String> lines = Splitter.on('\n').splitToList(unformattedSource);
+            StringBuilder failureText = new StringBuilder();
+            failureText
+                    .append("Failed to format '")
+                    .append(file.packageName)
+                    .append('.')
+                    .append(file.typeSpec.name)
+                    .append("'\n");
+            for (FormatterDiagnostic formatterDiagnostic : formatterDiagnostics) {
+                failureText
+                        .append(formatterDiagnostic.message())
+                        .append("\n")
+                        // Diagnostic values are one-indexed, while our list is zero-indexed.
+                        .append(lines.get(formatterDiagnostic.line() - 1))
+                        .append('\n')
+                        // Offset by two to convert from one-indexed to zero indexed values, and account for the caret.
+                        .append(Strings.repeat(" ", Math.max(0, formatterDiagnostic.column() - 2)))
+                        .append("^\n\n");
+            }
+            return CharMatcher.is('\n').trimFrom(failureText.toString());
+        } catch (RuntimeException e) {
+            return "Failed to format:\n" + unformattedSource;
+        }
+    }
+}

goethe/src/main/java/com/palantir/goethe/FormatterFacade.java

@@ -0,0 +1,24 @@
+/*
+ * (c) Copyright 2021 Palantir Technologies Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.palantir.goethe;
+
+import com.squareup.javapoet.JavaFile;
+
+interface FormatterFacade {
+
+    String formatSource(JavaFile file) throws GoetheException;
+}

goethe/src/main/java/com/palantir/goethe/Goethe.java

@@ -16,21 +16,14 @@
 
 package com.palantir.goethe;
 
-import com.google.common.base.CharMatcher;
 import com.google.common.base.Preconditions;
 import com.google.common.base.Splitter;
-import com.google.common.base.Strings;
-import com.palantir.javaformat.java.Formatter;
-import com.palantir.javaformat.java.FormatterDiagnostic;
-import com.palantir.javaformat.java.FormatterException;
-import com.palantir.javaformat.java.JavaFormatterOptions;
 import com.squareup.javapoet.JavaFile;
 import java.io.File;
 import java.io.IOException;
 import java.io.Writer;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.List;
 import javax.annotation.processing.Filer;
 import javax.lang.model.element.Element;
 import javax.tools.JavaFileObject;
@@ -46,9 +39,8 @@
  */
 public final class Goethe {
 
-    private static final Formatter JAVA_FORMATTER = Formatter.createFormatter(JavaFormatterOptions.builder()
-            .style(JavaFormatterOptions.Style.PALANTIR)
-            .build());
+    private static final FormatterFacade JAVA_FORMATTER =
+            new BootstrappingFormatterFacade(); // new DirectFormatterFacade();
 
     /**
      * Format a {@link JavaFile javapoet java file} into a {@link String}.
@@ -57,15 +49,7 @@ public final class Goethe {
      * @return Formatted source code
      */
     public static String formatAsString(JavaFile file) {
-        StringBuilder rawSource = new StringBuilder();
-        try {
-            file.writeTo(rawSource);
-            return JAVA_FORMATTER.formatSource(rawSource.toString());
-        } catch (FormatterException e) {
-            throw new GoetheException(generateMessage(file, rawSource.toString(), e.diagnostics()), e);
-        } catch (IOException e) {
-            throw new GoetheException("Formatting failed", e);
-        }
+        return JAVA_FORMATTER.formatSource(file);
     }
 
     /**
@@ -115,39 +99,6 @@ public static Path formatAndEmit(JavaFile file, Path baseDir) {
         }
     }
 
-    /**
-     * Attempt to provide as much actionable information as possible to understand why formatting is failing. This
-     * is common when generated code is incorrect and cannot compile, so we mustn't make it difficult to understand
-     * the problem.
-     */
-    private static String generateMessage(
-            JavaFile file, String unformattedSource, List<FormatterDiagnostic> formatterDiagnostics) {
-        try {
-            List<String> lines = Splitter.on('\n').splitToList(unformattedSource);
-            StringBuilder failureText = new StringBuilder();
-            failureText
-                    .append("Failed to format '")
-                    .append(file.packageName)
-                    .append('.')
-                    .append(file.typeSpec.name)
-                    .append("'\n");
-            for (FormatterDiagnostic formatterDiagnostic : formatterDiagnostics) {
-                failureText
-                        .append(formatterDiagnostic.message())
-                        .append("\n")
-                        // Diagnostic values are one-indexed, while our list is zero-indexed.
-                        .append(lines.get(formatterDiagnostic.line() - 1))
-                        .append('\n')
-                        // Offset by two to convert from one-indexed to zero indexed values, and account for the caret.
-                        .append(Strings.repeat(" ", Math.max(0, formatterDiagnostic.column() - 2)))
-                        .append("^\n\n");
-            }
-            return CharMatcher.is('\n').trimFrom(failureText.toString());
-        } catch (RuntimeException e) {
-            return "Failed to format:\n" + unformattedSource;
-        }
-    }
-
     private static String className(JavaFile file) {
         return file.packageName.isEmpty() ? file.typeSpec.name : file.packageName + "." + file.typeSpec.name;
     }

goethe/src/main/java/com/palantir/goethe/GoetheException.java

@@ -18,6 +18,10 @@
 
 /** Marker exception describing failures emitted from the Goethe library. */
 public final class GoetheException extends IllegalStateException {
+    GoetheException(String message) {
+        super(message);
+    }
+
     GoetheException(String message, Throwable cause) {
         super(message, cause);
     }