Some readability improvements for #230.

java/src/processing/mode/java/ErrorChecker.java

@@ -110,15 +110,7 @@ class ErrorChecker {
       List<Problem> cuProblems = iproblems.stream()
           // Filter Warnings if they are not enabled
           .filter(iproblem -> !(iproblem.isWarning() && !JavaMode.warningsEnabled))
-          // Hide a useless error which is produced when a line ends with
-          // an identifier without a semicolon. "Missing a semicolon" is
-          // also produced and is preferred over this one.
-          // (Syntax error, insert ":: IdentifierOrNew" to complete Expression)
-          // See: https://bugs.eclipse.org/bugs/show_bug.cgi?id=405780
-          .filter(iproblem -> !iproblem.getMessage()
-              .contains("Syntax error, insert \":: IdentifierOrNew\""))
-          .filter(iproblem -> !iproblem.getMessage()
-              .contains("must be defined in its own file"))
+          .filter(iproblem -> !(isIgnorableProblem(iproblem)))
           // Transform into our Problems
           .map(iproblem -> {
             JavaProblem p = convertIProblem(iproblem, ps);
@@ -155,6 +147,38 @@ class ErrorChecker {
   }
 
 
+  /**
+   * Determine if a problem can be suppressed from the user.
+   *
+   * <p>
+   * Determine if one can ignore an errors where an ignorable error is one
+   * "fixed" in later pipeline steps but can make JDT angry or do not actually
+   * cause issues when reaching javac.
+   * </p>
+   *
+   * @return True if ignoreable and false otherwise.
+   */
+  static private boolean isIgnorableProblem(IProblem iproblem) {
+    String message = iproblem.getMessage();
+
+    // Hide a useless error which is produced when a line ends with
+    // an identifier without a semicolon. "Missing a semicolon" is
+    // also produced and is preferred over this one.
+    // (Syntax error, insert ":: IdentifierOrNew" to complete Expression)
+    // See: https://bugs.eclipse.org/bugs/show_bug.cgi?id=405780
+    boolean ignorable = message.contains(
+        "Syntax error, insert \":: IdentifierOrNew\""
+    );
+
+    // It's ok if the file names do not line up during preprocessing.
+    ignorable = ignorable || message.contains(
+        "must be defined in its own file"
+    );
+
+    return ignorable;
+  }
+
+
   static private JavaProblem convertIProblem(IProblem iproblem, PreprocSketch ps) {
     SketchInterval in = ps.mapJavaToSketch(iproblem);
     if (in != SketchInterval.BEFORE_START) {

java/src/processing/mode/java/PreprocService.java

@@ -483,6 +483,7 @@ public class PreprocService {
     OffsetMapper parsableMapper = toParsable.getMapper();
 
     // Create intermediate AST for advanced preprocessing
+    // Wait on .java tabs due to speed since they don't go through preproc.
     CompileResults parseableCompile = compileInMemory(
         parsableStage,
         className,
@@ -496,13 +497,14 @@ public class PreprocService {
     toCompilable.addAll(SourceUtil.preprocessAST(parsableCU));
 
     // Transform code to compilable state
+    // Again, wait on .java tabs due to speed since they don't go through
+    // the preprocessor.
     String compilableStage = toCompilable.apply();
     OffsetMapper compilableMapper = toCompilable.getMapper();
-    char[] compilableStageChars = compilableStage.toCharArray();
 
     // Create compilable AST to get syntax problems
     CompileResults compileableCompile = compileInMemory(
-        compilableStageChars,
+        compilableStage,
         className,
         result.classPathArray,
         false
@@ -514,7 +516,8 @@ public class PreprocService {
       Arrays.stream(compilableCU.getProblems()).anyMatch(IProblem::isError);
 
     // Generate bindings after getting problems - avoids
-    // 'missing type' errors when there are syntax problems
+    // 'missing type' errors when there are syntax problems.
+    // Introduce .java tabs here for type resolution.
     CompileResults bindingsCompile;
     if (javaFiles.size() == 0) {
       bindingsCompile = compileInMemory(
@@ -599,6 +602,7 @@ public class PreprocService {
       String className, String[] classPathArray,
       List<JavaSketchCode> javaFiles, boolean resolveBindings) {
 
+    ProcessingASTRequester astRequester;
     List<Path> temporaryFilesList = new ArrayList<>();
     Map<String, Integer> javaFileMapping = new HashMap<>();
 
@@ -625,12 +629,12 @@ public class PreprocService {
     }
 
     // Compile
-    ProcessingASTRequester processingRequester = new ProcessingASTRequester();
+    astRequester = new ProcessingASTRequester(mainSource);
     parser.createASTs(
         temporaryFilesArray,
         null,
         new String[] {},
-        processingRequester,
+        astRequester,
         null
     );
 
@@ -639,8 +643,8 @@ public class PreprocService {
 
     // Return
     return new CompileResults(
-        processingRequester.getCompilationUnit(),
-        processingRequester.getProblems(),
+        astRequester.getMainCompilationUnit(),
+        astRequester.getProblems(),
         javaFileMapping
     );
   }

java/src/processing/mode/java/PreprocSketch.java

@@ -81,8 +81,8 @@ public class PreprocSketch {
           javaFileMapping.get(originalFile),
           iproblem.getSourceStart(),
           iproblem.getSourceEnd() + 1,
-          iproblem.getSourceStart(), // Is outside sketch code
-          iproblem.getSourceEnd() + 1  // Is outside sketch code
+          iproblem.getSourceStart(), // Is outside main sketch code
+          iproblem.getSourceEnd() + 1  // Is outside main sketch code
       );
     } else {
       return mapJavaToSketch(