jscomp: allow using AbstractCommandLineRunner.exitCodeHandler in non-…

…test mode.

{Abstract,}CommandLineRunner do a lot of output wrangling including generating source line maps
which makes it a decent programmatic interface, especially when many flags are pass-through.

Doing work after it exits though is tough because run() calls System.exit.

This cleans up uses of System.err and System.exit so that local versions err,exitCodeHandler
are always used, and allows overriding exitCodeHandler in non-test mode.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=130312217

src/com/google/javascript/jscomp/AbstractCommandLineRunner.java

@@ -191,7 +191,7 @@ public abstract class AbstractCommandLineRunner<A extends Compiler,
   private Supplier<List<SourceFile>> externsSupplierForTesting = null;
   private Supplier<List<SourceFile>> inputsSupplierForTesting = null;
   private Supplier<List<JSModule>> modulesSupplierForTesting = null;
-  private Function<Integer, Boolean> exitCodeReceiverForTesting = null;
+  private Function<Integer, Void> exitCodeReceiver = SystemExitCodeReceiver.INSTANCE;
   private Map<String, String> rootRelativePathsMap = null;
 
   private Map<String, String> parsedModuleWrappers = null;
@@ -234,14 +234,22 @@ void enableTestMode(
       Supplier<List<SourceFile>> externsSupplier,
       Supplier<List<SourceFile>> inputsSupplier,
       Supplier<List<JSModule>> modulesSupplier,
-      Function<Integer, Boolean> exitCodeReceiver) {
+      Function<Integer, Void> exitCodeReceiver) {
     Preconditions.checkArgument(
         inputsSupplier == null ^ modulesSupplier == null);
     testMode = true;
     this.externsSupplierForTesting = externsSupplier;
     this.inputsSupplierForTesting = inputsSupplier;
     this.modulesSupplierForTesting = modulesSupplier;
-    this.exitCodeReceiverForTesting = exitCodeReceiver;
+    this.exitCodeReceiver = exitCodeReceiver;
+  }
+
+  /**
+   * @param newExitCodeReceiver receives a non-zero integer to indicate a
+   *    problem during execution or 0i to indicate success.
+   */
+  public void setExitCodeReceiver(Function<Integer, Void> newExitCodeReceiver) {
+    this.exitCodeReceiver = Preconditions.checkNotNull(newExitCodeReceiver);
   }
 
   /**
@@ -540,25 +548,21 @@ public final void run() {
         result = doRun();
       }
     } catch (AbstractCommandLineRunner.FlagUsageException e) {
-      System.err.println(e.getMessage());
+      err.println(e.getMessage());
       result = -1;
     } catch (Throwable t) {
-      t.printStackTrace();
+      t.printStackTrace(err);
       result = -2;
     }
 
-    if (testMode) {
-      exitCodeReceiverForTesting.apply(result);
-    } else {
-      System.exit(result);
-    }
+    exitCodeReceiver.apply(result);
   }
 
   /**
    * Returns the PrintStream for writing errors associated with this
    * AbstractCommandLineRunner.
    */
-  protected PrintStream getErrorPrintStream() {
+  protected final PrintStream getErrorPrintStream() {
     return err;
   }
 
@@ -1533,7 +1537,7 @@ private Writer fileNameToLegacyOutputWriter(String fileName)
     if (fileName == null) {
       return null;
     }
-    if (testMode) {
+    if (isInTestMode()) {
       return new StringWriter();
     }
 
@@ -1548,7 +1552,7 @@ private Writer fileNameToOutputWriter2(String fileName) throws IOException {
     if (fileName == null) {
       return null;
     }
-    if (testMode) {
+    if (isInTestMode()) {
       return new StringWriter();
     }
 
@@ -2734,4 +2738,26 @@ public int getNumJsFiles() {
       return numJsFiles;
     }
   }
+
+
+  static final class SystemExitCodeReceiver implements Function<Integer, Void> {
+    static final SystemExitCodeReceiver INSTANCE = new SystemExitCodeReceiver();
+
+    private SystemExitCodeReceiver() {
+      // singleton
+    }
+
+    @Override
+    public Void apply(Integer exitCode) {
+      int exitCodeValue = Preconditions.checkNotNull(exitCode);
+      // Don't spuriously report success.
+      // Posix conventions only guarantee that 8b are significant.
+      byte exitCodeByte = (byte) exitCodeValue;
+      if (exitCodeByte == 0 && exitCodeValue != 0) {
+        exitCodeByte = (byte) -1;
+      }
+      System.exit(exitCodeByte);
+      return null;
+    }
+  }
 }

test/com/google/javascript/jscomp/CommandLineRunnerTest.java

@@ -2201,10 +2201,11 @@ private Compiler compile(String[] original) {
         Suppliers.ofInstance(externs),
         inputsSupplier,
         modulesSupplier,
-        new Function<Integer, Boolean>() {
+        new Function<Integer, Void>() {
           @Override
-          public Boolean apply(Integer code) {
-            return exitCodes.add(code);
+          public Void apply(Integer code) {
+            exitCodes.add(code);
+            return null;
           }
         });
     runner.run();