Print the problem line as context in error messages

PiperOrigin-RevId: 675207795

Author: cushon

core/src/main/java/com/google/googlejavaformat/java/FormatterException.java

@@ -16,10 +16,13 @@
 
 import static java.util.Locale.ENGLISH;
 
+import com.google.common.base.CharMatcher;
+import com.google.common.base.Splitter;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
 import com.google.googlejavaformat.FormatterDiagnostic;
 import java.util.List;
+import java.util.regex.Pattern;
 import javax.tools.Diagnostic;
 import javax.tools.JavaFileObject;
 
@@ -55,4 +58,22 @@ private static FormatterDiagnostic toFormatterDiagnostic(Diagnostic<?> input) {
  return FormatterDiagnostic.create(
  (int) input.getLineNumber(), (int) input.getColumnNumber(), input.getMessage(ENGLISH));
  }
+
+ public String formatDiagnostics(String path, String input) {
+ List<String> lines = Splitter.on(NEWLINE_PATTERN).splitToList(input);
+ StringBuilder sb = new StringBuilder();
+ for (FormatterDiagnostic diagnostic : diagnostics()) {
+ sb.append(path).append(":").append(diagnostic).append(System.lineSeparator());
+ int line = diagnostic.line();
+ int column = diagnostic.column();
+ if (line != -1 && column != -1) {
+ sb.append(CharMatcher.breakingWhitespace().trimTrailingFrom(lines.get(line - 1)))
+ .append(System.lineSeparator());
+ sb.append(" ".repeat(column)).append('^').append(System.lineSeparator());
+ }
+ }
+ return sb.toString();
+ }
+
+ private static final Pattern NEWLINE_PATTERN = Pattern.compile("\\R");
 }

core/src/main/java/com/google/googlejavaformat/java/Main.java

@@ -20,7 +20,6 @@
 
 import com.google.common.io.ByteStreams;
 import com.google.common.util.concurrent.MoreExecutors;
-import com.google.googlejavaformat.FormatterDiagnostic;
 import com.google.googlejavaformat.java.JavaFormatterOptions.Style;
 import java.io.IOError;
 import java.io.IOException;
@@ -175,9 +174,7 @@ private int formatFiles(CommandLineOptions parameters, JavaFormatterOptions opti
  for (FormatFileCallable.Result result : results) {
  Path path = result.path();
  if (result.exception() != null) {
- for (FormatterDiagnostic diagnostic : result.exception().diagnostics()) {
- errWriter.println(path + ":" + diagnostic);
- }
+ errWriter.print(result.exception().formatDiagnostics(path.toString(), result.input()));
  allOk = false;
  continue;
  }
@@ -224,9 +221,7 @@ private int formatStdin(CommandLineOptions parameters, JavaFormatterOptions opti
  FormatFileCallable.Result result =
  new FormatFileCallable(parameters, null, input, options).call();
  if (result.exception() != null) {
- for (FormatterDiagnostic diagnostic : result.exception().diagnostics()) {
- errWriter.println(stdinFilename + ":" + diagnostic);
- }
+ errWriter.print(result.exception().formatDiagnostics(stdinFilename, input));
  ok = false;
  } else {
  String output = result.output();

core/src/test/java/com/google/googlejavaformat/java/MainTest.java

@@ -635,4 +635,29 @@ public void reorderModifiersOptionTest() throws Exception {
  .formatSource(source))
  .isEqualTo(source);
  }
+
+ @Test
+ public void badIdentifier() throws Exception {
+ Path path = testFolder.newFile("Test.java").toPath();
+ String[] input = {
+ "class Test {", //
+ " void f(int package) {}",
+ "}",
+ "",
+ };
+ String source = joiner.join(input);
+ Files.writeString(path, source, UTF_8);
+ StringWriter out = new StringWriter();
+ StringWriter err = new StringWriter();
+ Main main = new Main(new PrintWriter(out, true), new PrintWriter(err, true), System.in);
+ int errorCode = main.format(path.toAbsolutePath().toString());
+ assertWithMessage("Error Code").that(errorCode).isEqualTo(1);
+ String[] expected = {
+ path + ":2:14: error: <identifier> expected", //
+ " void f(int package) {}",
+ " ^",
+ "",
+ };
+ assertThat(err.toString()).isEqualTo(joiner.join(expected));
+ }
 }