Use shorter DartElementLocation.

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

Index: pkg/analyzer/lib/src/generated/element.dart
diff --git a/pkg/analyzer/lib/src/generated/element.dart b/pkg/analyzer/lib/src/generated/element.dart
index a1fc144dbf098860bb539023d658610914e67a6a..cc4512886badab74b84c9233b426aa13d86c12a7 100644
--- a/pkg/analyzer/lib/src/generated/element.dart
+++ b/pkg/analyzer/lib/src/generated/element.dart
@@ -21,6 +21,7 @@ import 'sdk.dart' show DartSdk;
 import 'source.dart';
 import 'utilities_collection.dart';
 import 'utilities_dart.dart';
+import 'element.dart';
 
 /**
  * Information about Angular application.
@@ -2399,6 +2400,7 @@ class CompilationUnitElementImpl extends UriReferencedElementImpl implements
   void visitChildren(ElementVisitor visitor) {
     super.visitChildren(visitor);
     safelyVisitChildren(_accessors, visitor);
+    safelyVisitChildren(_enums, visitor);
     safelyVisitChildren(_functions, visitor);
     safelyVisitChildren(_typeAliases, visitor);
     safelyVisitChildren(_types, visitor);
@@ -2972,6 +2974,11 @@ class DynamicElementImpl extends ElementImpl {
   ElementKind get kind => ElementKind.DYNAMIC;
 
   @override
+  ElementLocation get location {
+    return new DartElementLocation(null, null, nameOffset, kind);
+  }
+
+  @override
   accept(ElementVisitor visitor) => null;
 }
 
@@ -3559,7 +3566,20 @@ abstract class ElementImpl implements Element {
       getAncestor((element) => element is LibraryElement);
 
   @override
-  ElementLocation get location => new ElementLocationImpl.con1(this);
+  ElementLocation get location {
+    // TODO(scheglov) add separate DartElementImpl

[Brian Wilkerson, 2014/11/18 15:11:22]

I don't know what that means.

+    LibraryElement library = this.library;
+    if (library == null) {
+      return new DartElementLocation(null, null, nameOffset, kind);
+    }
+    String librarySourceEncoding = library.source.encoding;
+    String unitSourceEncoding = source.encoding;
+    return new DartElementLocation(
+        librarySourceEncoding,
+        unitSourceEncoding,
+        nameOffset,
+        kind);
+  }
 
   @override
   String get name => _name;
@@ -3913,172 +3933,51 @@ class ElementKind extends Enum<ElementKind> {
 }
 
 /**
- * The interface `ElementLocation` defines the behavior of objects that represent the location
- * of an element within the element model.
+ * The interface `ElementLocation` defines the behavior of objects that
+ * represent the location of an element within the element model.
  */
 abstract class ElementLocation {
-  /**
-   * Return the path to the element whose location is represented by this object. Clients must not
-   * modify the returned array.
-   *
-   * @return the path to the element whose location is represented by this object
-   */
-  List<String> get components;
-
-  /**
-   * Return an encoded representation of this location that can be used to create a location that is
-   * equal to this location.
-   *
-   * @return an encoded representation of this location
-   */
-  String get encoding;
 }
 
 /**
- * Instances of the class `ElementLocationImpl` implement an [ElementLocation].
+ * The interface `DartElementLocation` defines the behavior of objects that
+ * represent the location of a Dart element within the element model.
  */
-class ElementLocationImpl implements ElementLocation {
-  /**
-   * The character used to separate components in the encoded form.
-   */
-  static int _SEPARATOR_CHAR = 0x3B;
-
+class DartElementLocation implements ElementLocation {
   /**
-   * The path to the element whose location is represented by this object.
+   * An encoded representation of the library source that contains this element.
    */
-  List<String> _components;
+  final String librarySourceEncoding;
 
   /**
-   * Initialize a newly created location to represent the given element.
-   *
-   * @param element the element whose location is being represented
+   * An encoded representation of the unit source that contains this element.
    */
-  ElementLocationImpl.con1(Element element) {
-    List<String> components = new List<String>();
-    Element ancestor = element;
-    while (ancestor != null) {
-      components.insert(0, (ancestor as ElementImpl).identifier);
-      ancestor = ancestor.enclosingElement;
-    }
-    this._components = components;
-  }
+  final String unitSourceEncoding;
 
   /**
-   * Initialize a newly created location from the given encoded form.
-   *
-   * @param encoding the encoded form of a location
+   * The offset of the name of this element in the file that contains
+   * the declaration of this element, or `-1` if this element is synthetic,
+   * does not have a name, or otherwise does not have an offset.
    */
-  ElementLocationImpl.con2(String encoding) {
-    this._components = _decode(encoding);
-  }
+  final int nameOffset;
 
   /**
-   * Initialize a newly created location from the given components.
-   *
-   * @param components the components of a location
+   * The kind of this element.
    */
-  ElementLocationImpl.con3(List<String> components) {
-    this._components = components;
-  }
-
-  @override
-  List<String> get components => _components;
+  final ElementKind kind;
 
-  @override
-  String get encoding {
-    StringBuffer buffer = new StringBuffer();
-    int length = _components.length;
-    for (int i = 0; i < length; i++) {
-      if (i > 0) {
-        buffer.writeCharCode(_SEPARATOR_CHAR);
-      }
-      _encode(buffer, _components[i]);
-    }
-    return buffer.toString();
-  }
-
-  @override
-  int get hashCode {
-    int result = 1;
-    for (int i = 0; i < _components.length; i++) {
-      String component = _components[i];
-      result = 31 * result + component.hashCode;
-    }
-    return result;
-  }
-
-  @override
-  bool operator ==(Object object) {
-    if (identical(this, object)) {
-      return true;
-    }
-    if (object is! ElementLocationImpl) {
-      return false;
-    }
-    ElementLocationImpl location = object as ElementLocationImpl;
-    List<String> otherComponents = location._components;
-    int length = _components.length;
-    if (otherComponents.length != length) {
-      return false;
-    }
-    for (int i = 0; i < length; i++) {
-      if (_components[i] != otherComponents[i]) {
-        return false;
-      }
-    }
-    return true;
-  }
+  DartElementLocation(this.librarySourceEncoding, this.unitSourceEncoding,
+      this.nameOffset, this.kind);
 
   @override
-  String toString() => encoding;
-
-  /**
-   * Decode the encoded form of a location into an array of components.
-   *
-   * @param encoding the encoded form of a location
-   * @return the components that were encoded
-   */
-  List<String> _decode(String encoding) {
-    List<String> components = new List<String>();
-    StringBuffer buffer = new StringBuffer();
-    int index = 0;
-    int length = encoding.length;
-    while (index < length) {
-      int currentChar = encoding.codeUnitAt(index);
-      if (currentChar == _SEPARATOR_CHAR) {
-        if (index + 1 < length &&
-            encoding.codeUnitAt(index + 1) == _SEPARATOR_CHAR) {
-          buffer.writeCharCode(_SEPARATOR_CHAR);
-          index += 2;
-        } else {
-          components.add(buffer.toString());
-          buffer = new StringBuffer();
-          index++;
-        }
-      } else {
-        buffer.writeCharCode(currentChar);
-        index++;
-      }
-    }
-    components.add(buffer.toString());
-    return components;
-  }
-
-  /**
-   * Append an encoded form of the given component to the given builder.
-   *
-   * @param builder the builder to which the encoded component is to be appended
-   * @param component the component to be appended to the builder
-   */
-  void _encode(StringBuffer buffer, String component) {
-    int length = component.length;
-    for (int i = 0; i < length; i++) {
-      int currentChar = component.codeUnitAt(i);
-      if (currentChar == _SEPARATOR_CHAR) {
-        buffer.writeCharCode(_SEPARATOR_CHAR);
-      }
-      buffer.writeCharCode(currentChar);
+  bool operator ==(Object other) {
+    if (other is DartElementLocation) {
+      return other.librarySourceEncoding == librarySourceEncoding &&
+          other.unitSourceEncoding == unitSourceEncoding &&
+          other.nameOffset == nameOffset &&
+          other.kind == kind;
     }
+    return false;
   }
 }
 
@@ -8589,6 +8488,51 @@ class LibraryElementImpl extends ElementImpl implements LibraryElement {
     return null;
   }
 
+  /**
+   * Returns the child [Element] of this library.
+   *
+   * [unitSourceEncoding] - the encoding of the unit.
+   * [offset] - the name offset of the element.
+   * [kind] - the kind of the element.
+   */
+  ElementImpl getChildElement(String unitSourceEncoding, int offset,
+      ElementKind kind) {
+    for (CompilationUnitElement unit in units) {
+      if (unit.source.encoding == unitSourceEncoding) {
+        ElementImpl element = _findElementAt(unit, offset, kind);
+        if (element != null) {
+          return element;
+        }
+        break;
+      }
+    }
+    for (ImportElement importElement in _imports) {
+      if (importElement.nameOffset == offset) {
+        return importElement as ImportElementImpl;
+      }
+    }
+    for (ExportElement exportElement in _exports) {
+      if (exportElement.nameOffset == offset) {
+        return exportElement as ExportElementImpl;
+      }
+    }
+    return null;
+  }
+
+  ElementImpl _findElementAt(CompilationUnitElement unit, int offset,

[Brian Wilkerson, 2014/11/18 15:11:22]

Seems like this should either be moved to
CompilationUnitElementImpl.getChildElement(int offset, ElementKind kind) or
encapsulated in the class ElementLocator (see comment below) and inlined above.

+      ElementKind kind) {
+    if (offset == -1) {
+      return unit as ElementImpl;
+    }
+    _FindElementAt visitor = new _FindElementAt(offset, kind);
+    try {
+      unit.accept(visitor);
+    } on _FindElementAtDone catch (e) {
+      return visitor.result;
+    }
+    return null;
+  }
+
   @override
   List<ImportElement> getImportsWithPrefix(PrefixElement prefixElement) {
     int count = _imports.length;
@@ -12470,3 +12414,25 @@ class VoidTypeImpl extends TypeImpl implements VoidType {
       List<DartType> parameterTypes) =>
       this;
 }
+
+
+class _FindElementAt extends GeneralizingElementVisitor {

[Brian Wilkerson, 2014/11/18 15:11:22]

I'm not sure why this is a private class. Seems like it ought to be a general
purpose class similar to NodeLocator (perhaps named ElementLocator) with a 
utility method that handles catching the exception.

+  final int offset;
+  final ElementKind kind;
+  Element result;
+
+  _FindElementAt(this.offset, this.kind);
+
+  @override
+  visitElement(Element element) {
+    if (element.nameOffset == offset && element.kind == kind) {
+      result = element;
+      throw new _FindElementAtDone();
+    }
+    super.visitElement(element);
+  }
+}
+
+
+class _FindElementAtDone {
+}