pass library files not directories to analysis server

editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/analysis/Context.java

 /*
  * Copyright 2012 Dart project authors.
  * 
  * Licensed under the Eclipse License v1.0 (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.eclipse.org/legal/epl-v10.html
  * 
  * 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
@@ skipping 84 matching lines @@
   /**
    * Parse the specified file, without adding the library to the list of libraries to be tracked.
    * 
    * @param libraryFile the library containing the dart file to be parsed (not <code>null</code>)
    * @param dartFile the dart file to be parsed (not <code>null</code>). This may be the same as the
    *          libraryFile
    * @param callback a listener that will be notified when the library file has been parsed or
    *          <code>null</code> if none
    */
   public void parse(File libraryFile, File dartFile, ParseCallback callback) {
+    if (!libraryFile.isAbsolute()) {
+      throw new IllegalArgumentException("File path must be absolute: " + libraryFile);
+    }
+    if (libraryFile.isDirectory()) {
+      throw new IllegalArgumentException("Cannot parse a directory: " + libraryFile);
+    }
     String relPath = libraryFile.toURI().relativize(dartFile.toURI()).getPath();
     server.queueNewTask(new ParseFileTask(server, this, libraryFile, relPath, dartFile, callback));
   }
 
   /**
    * Resolve the specified library. Similar to {@link #analyze(File)}, but does not add the library
    * to the list of libraries to be tracked.
    * 
    * @param libraryFile the library file (not <code>null</code>).
    * @param milliseconds the number of milliseconds to wait for the library to be resolved.
@@ skipping 15 matching lines @@
    * to the list of libraries to be tracked.
    * 
    * @param libraryFile the library file (not <code>null</code>)
    * @param callback a listener that will be notified when the library has been resolved or
    *          <code>null</code> if none
    */
   public void resolve(File libraryFile, ResolveCallback callback) {
     if (!libraryFile.isAbsolute()) {
       throw new IllegalArgumentException("File path must be absolute: " + libraryFile);
     }
+    if (libraryFile.isDirectory()) {
+      throw new IllegalArgumentException("Cannot resolve a directory: " + libraryFile);
+    }
     server.queueNewTask(new AnalyzeLibraryTask(server, this, libraryFile, callback));
   }
 
   void cacheLibrary(Library library) {
     libraryCache.put(library.getFile(), library);
   }
 
   void cacheUnresolvedUnit(File file, DartUnit unit) {
     unresolvedUnits.put(file.toURI(), unit);
   }
@@ skipping 145 matching lines @@
     if (oldArray.length == 0) {
       return new Library[] {library};
     }
     int oldLen = oldArray.length;
     Library[] newArray = new Library[oldLen + 1];
     System.arraycopy(oldArray, 0, newArray, 0, oldLen);
     newArray[oldLen] = library;
     return newArray;
   }
 }