Fix for translation of \!= to \!identical(), but use == and \!= for Enum.

pkg/analyzer/lib/src/generated/source.dart

Index: pkg/analyzer/lib/src/generated/source.dart
diff --git a/pkg/analyzer/lib/src/generated/source.dart b/pkg/analyzer/lib/src/generated/source.dart
index 446c8eaa27ded1992da4d0430b85ebc73958f686..7dbcacd11e3e4018dbf86032e4a02395c35bc848 100644
--- a/pkg/analyzer/lib/src/generated/source.dart
+++ b/pkg/analyzer/lib/src/generated/source.dart
@@ -69,7 +69,7 @@ class SourceFactory {
   /**
    * The resolvers used to resolve absolute URI's.
    */
-  List<UriResolver> _resolvers;
+  final List<UriResolver> _resolvers;
 
   /**
    * The predicate to determine is [Source] is local.
@@ -81,9 +81,7 @@ class SourceFactory {
    *
    * @param resolvers the resolvers used to resolve absolute URI's
    */
-  SourceFactory(List<UriResolver> resolvers) {
-    this._resolvers = resolvers;
-  }
+  SourceFactory(this._resolvers);
 
   /**
    * Return a source object representing the given absolute URI, or `null` if the URI is not a
@@ -160,9 +158,9 @@ class SourceFactory {
 
   /**
    * Return a source object representing the URI that results from resolving the given (possibly
-   * relative) contained URI against the URI associated with an existing source object, or
-   * `null` if either the contained URI is invalid or if it cannot be resolved against the
-   * source object's URI.
+   * relative) contained URI against the URI associated with an existing source object, whether or
+   * not the resulting source exists, or `null` if either the contained URI is invalid or if
+   * it cannot be resolved against the source object's URI.
    *
    * @param containingSource the source containing the given URI
    * @param containedUri the (possibly relative) URI to be resolved against the containing source
@@ -181,10 +179,11 @@ class SourceFactory {
   }
 
   /**
-   * Return an absolute URI that represents the given source.
+   * Return an absolute URI that represents the given source, or `null` if a valid URI cannot
+   * be computed.
    *
    * @param source the source to get URI for
-   * @return the absolute URI representing the given source, may be `null`
+   * @return the absolute URI representing the given source
    */
   Uri restoreUri(Source source) {
     for (UriResolver resolver in _resolvers) {
@@ -239,8 +238,9 @@ abstract class UriResolver {
   /**
    * If this resolver should be used for URI's of the given kind, resolve the given absolute URI.
    * The URI does not need to have the scheme handled by this resolver if the kind matches. Return a
-   * [Source] representing the file to which it was resolved, or `null` if it
-   * could not be resolved.
+   * [Source] representing the file to which it was resolved, whether or not the
+   * resulting source exists, or `null` if it could not be resolved because the URI is
+   * invalid.
    *
    * @param kind the kind of URI that was originally resolved in order to produce an encoding with
    *          the given URI
@@ -251,7 +251,8 @@ abstract class UriResolver {
 
   /**
    * Resolve the given absolute URI. Return a [Source] representing the file to which
-   * it was resolved, or `null` if it could not be resolved.
+   * it was resolved, whether or not the resulting source exists, or `null` if it could not be
+   * resolved because the URI is invalid.
    *
    * @param uri the URI to be resolved
    * @return a [Source] representing the file to which given URI was resolved
@@ -259,17 +260,34 @@ abstract class UriResolver {
   Source resolveAbsolute(Uri uri);
 
   /**
-   * Return an absolute URI that represents the given source.
+   * Return an absolute URI that represents the given source, or `null` if a valid URI cannot
+   * be computed.
    *
    * @param source the source to get URI for
-   * @return the absolute URI representing the given source, may be `null`
+   * @return the absolute URI representing the given source
    */
   Uri restoreAbsolute(Source source) => null;
 }
 
 /**
  * The interface `Source` defines the behavior of objects representing source code that can be
- * compiled.
+ * analyzed by the analysis engine.
+ *
+ * Implementations of this interface need to be aware of some assumptions made by the analysis
+ * engine concerning sources:
+ * * Sources are not required to be unique. That is, there can be multiple instances representing
+ * the same source.
+ * * Sources are long lived. That is, the engine is allowed to hold on to a source for an extended
+ * period of time and that source must continue to report accurate and up-to-date information.
+ * Because of these assumptions, most implementations will not maintain any state but will delegate
+ * to an authoritative system of record in order to implement this API. For example, a source that
+ * represents files on disk would typically query the file system to determine the state of the
+ * file.
+ *
+ * If the instances that implement this API are the system of record, then they will typically be
+ * unique. In that case, sources that are created that represent non-existent files must also be
+ * retained so that if those files are created at a later date the long-lived sources representing
+ * those files will know that they now exist.
  */
 abstract class Source {
   /**
@@ -418,29 +436,29 @@ class SourceKind extends Enum<SourceKind> {
   /**
    * A source containing HTML. The HTML might or might not contain Dart scripts.
    */
-  static final SourceKind HTML = new SourceKind('HTML', 0);
+  static const SourceKind HTML = const SourceKind('HTML', 0);
 
   /**
    * A Dart compilation unit that is not a part of another library. Libraries might or might not
    * contain any directives, including a library directive.
    */
-  static final SourceKind LIBRARY = new SourceKind('LIBRARY', 1);
+  static const SourceKind LIBRARY = const SourceKind('LIBRARY', 1);
 
   /**
    * A Dart compilation unit that is part of another library. Parts contain a part-of directive.
    */
-  static final SourceKind PART = new SourceKind('PART', 2);
+  static const SourceKind PART = const SourceKind('PART', 2);
 
   /**
    * An unknown kind of source. Used both when it is not possible to identify the kind of a source
    * and also when the kind of a source is not known without performing a computation and the client
    * does not want to spend the time to identify the kind.
    */
-  static final SourceKind UNKNOWN = new SourceKind('UNKNOWN', 3);
+  static const SourceKind UNKNOWN = const SourceKind('UNKNOWN', 3);
 
-  static final List<SourceKind> values = [HTML, LIBRARY, PART, UNKNOWN];
+  static const List<SourceKind> values = const [HTML, LIBRARY, PART, UNKNOWN];
 
-  SourceKind(String name, int ordinal) : super(name, ordinal);
+  const SourceKind(String name, int ordinal) : super(name, ordinal);
 }
 
 /**
@@ -451,24 +469,24 @@ class UriKind extends Enum<UriKind> {
   /**
    * A 'dart:' URI.
    */
-  static final UriKind DART_URI = new UriKind('DART_URI', 0, 0x64);
+  static const UriKind DART_URI = const UriKind('DART_URI', 0, 0x64);
 
   /**
    * A 'file:' URI.
    */
-  static final UriKind FILE_URI = new UriKind('FILE_URI', 1, 0x66);
+  static const UriKind FILE_URI = const UriKind('FILE_URI', 1, 0x66);
 
   /**
    * A 'package:' URI referencing source package itself.
    */
-  static final UriKind PACKAGE_SELF_URI = new UriKind('PACKAGE_SELF_URI', 2, 0x73);
+  static const UriKind PACKAGE_SELF_URI = const UriKind('PACKAGE_SELF_URI', 2, 0x73);
 
   /**
    * A 'package:' URI.
    */
-  static final UriKind PACKAGE_URI = new UriKind('PACKAGE_URI', 3, 0x70);
+  static const UriKind PACKAGE_URI = const UriKind('PACKAGE_URI', 3, 0x70);
 
-  static final List<UriKind> values = [DART_URI, FILE_URI, PACKAGE_SELF_URI, PACKAGE_URI];
+  static const List<UriKind> values = const [DART_URI, FILE_URI, PACKAGE_SELF_URI, PACKAGE_URI];
 
   /**
    * Return the URI kind represented by the given encoding, or `null` if there is no kind with
@@ -496,16 +514,14 @@ class UriKind extends Enum<UriKind> {
   /**
    * The single character encoding used to identify this kind of URI.
    */
-  int encoding = 0;
+  final int encoding;
 
   /**
    * Initialize a newly created URI kind to have the given encoding.
    *
    * @param encoding the single character encoding used to identify this kind of URI.
    */
-  UriKind(String name, int ordinal, int encoding) : super(name, ordinal) {
-    this.encoding = encoding;
-  }
+  const UriKind(String name, int ordinal, this.encoding) : super(name, ordinal);
 }
 
 /**
@@ -521,13 +537,13 @@ class SourceRange {
    * The 0-based index of the first character of the source code for this element, relative to the
    * source buffer in which this element is contained.
    */
-  int offset = 0;
+  final int offset;
 
   /**
    * The number of characters of the source code for this element, relative to the source buffer in
    * which this element is contained.
    */
-  int length = 0;
+  final int length;
 
   /**
    * Initialize a newly created source range using the given offset and the given length.
@@ -535,10 +551,7 @@ class SourceRange {
    * @param offset the given offset
    * @param length the given length
    */
-  SourceRange(int offset, int length) {
-    this.offset = offset;
-    this.length = length;
-  }
+  SourceRange(this.offset, this.length);
 
   /**
    * @return `true` if <code>x</code> is in [offset, offset + length) interval.
@@ -657,9 +670,17 @@ abstract class SourceContainer {
  */
 class DartUriResolver extends UriResolver {
   /**
+   * Return `true` if the given URI is a `dart-ext:` URI.
+   *
+   * @param uriContent the textual representation of the URI being tested
+   * @return `true` if the given URI is a `dart-ext:` URI
+   */
+  static bool isDartExtUri(String uriContent) => uriContent != null && uriContent.startsWith(_DART_EXT_SCHEME);
+
+  /**
    * The Dart SDK against which URI's are to be resolved.
    */
-  DartSdk _sdk;
+  final DartSdk _sdk;
 
   /**
    * The name of the `dart` scheme.
@@ -667,6 +688,11 @@ class DartUriResolver extends UriResolver {
   static String _DART_SCHEME = "dart";
 
   /**
+   * The prefix of a URI using the dart-ext scheme to reference a native code library.
+   */
+  static String _DART_EXT_SCHEME = "dart-ext:";
+
+  /**
    * Return `true` if the given URI is a `dart:` URI.
    *
    * @param uri the URI being tested
@@ -680,13 +706,11 @@ class DartUriResolver extends UriResolver {
    *
    * @param sdk the Dart SDK against which URI's are to be resolved
    */
-  DartUriResolver(DartSdk sdk) {
-    this._sdk = sdk;
-  }
+  DartUriResolver(this._sdk);
 
   @override
   Source fromEncoding(UriKind kind, Uri uri) {
-    if (identical(kind, UriKind.DART_URI)) {
+    if (kind == UriKind.DART_URI) {
       return _sdk.fromEncoding(kind, uri);
     }
     return null;
@@ -716,7 +740,7 @@ class LineInfo {
   /**
    * An array containing the offsets of the first character of each line in the source code.
    */
-  List<int> _lineStarts;
+  final List<int> _lineStarts;
 
   /**
    * Initialize a newly created set of line information to represent the data encoded in the given
@@ -724,13 +748,12 @@ class LineInfo {
    *
    * @param lineStarts the offsets of the first character of each line in the source code
    */
-  LineInfo(List<int> lineStarts) {
-    if (lineStarts == null) {
+  LineInfo(this._lineStarts) {
+    if (_lineStarts == null) {
       throw new IllegalArgumentException("lineStarts must be non-null");
-    } else if (lineStarts.length < 1) {
+    } else if (_lineStarts.length < 1) {
       throw new IllegalArgumentException("lineStarts must be non-empty");
     }
-    this._lineStarts = lineStarts;
   }
 
   /**
@@ -758,12 +781,12 @@ class LineInfo_Location {
   /**
    * The one-based index of the line containing the character.
    */
-  int lineNumber = 0;
+  final int lineNumber;
 
   /**
    * The one-based index of the column containing the character.
    */
-  int columnNumber = 0;
+  final int columnNumber;
 
   /**
    * Initialize a newly created location to represent the location of the character at the given
@@ -772,10 +795,7 @@ class LineInfo_Location {
    * @param lineNumber the one-based index of the line containing the character
    * @param columnNumber the one-based index of the column containing the character
    */
-  LineInfo_Location(int lineNumber, int columnNumber) {
-    this.lineNumber = lineNumber;
-    this.columnNumber = columnNumber;
-  }
+  LineInfo_Location(this.lineNumber, this.columnNumber);
 }
 
 /**