Add sharedfrontend package

pkg/sharedfrontend/lib/src/access_semantics.dart

Index: pkg/sharedfrontend/lib/src/access_semantics.dart
diff --git a/pkg/sharedfrontend/lib/src/access_semantics.dart b/pkg/sharedfrontend/lib/src/access_semantics.dart
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+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/**
+ * Code for classifying the semantics of identifiers appearing in a Dart file.
+ */
+library sharedfrontend.access_semantics;
+
+import '../elements.dart';
+
+/**
+ * Enum representing the different kinds of destinations which a property
+ * access or method or function invocation might refer to.
+ */
+class AccessKind {
+  /**
+   * The destination of the access is an instance method, property, or field
+   * of a class, and thus must be determined dynamically.
+   */
+  static const AccessKind DYNAMIC = const AccessKind._('DYNAMIC');
+
+  /**
+   * The destination of the access is a function that is defined locally within
+   * an enclosing function or method.
+   */
+  static const AccessKind LOCAL_FUNCTION = const AccessKind._('LOCAL_FUNCTION');
+
+  /**
+   * The destination of the access is a variable that is defined locally within
+   * an enclosing function or method.
+   */
+  static const AccessKind LOCAL_VARIABLE = const AccessKind._('LOCAL_VARIABLE');
+
+  /**
+   * The destination of the access is a variable that is defined as a parameter
+   * to an enclosing function or method.
+   */
+  static const AccessKind PARAMETER = const AccessKind._('PARAMETER');
+
+  /**
+   * The destination of the access is a field that is defined statically within
+   * a class, or a top level variable within a library.
+   */
+  static const AccessKind STATIC_FIELD = const AccessKind._('STATIC_FIELD');
+
+  /**
+   * The destination of the access is a method that is defined statically
+   * within a class, or at top level within a library.
+   */
+  static const AccessKind STATIC_METHOD = const AccessKind._('STATIC_METHOD');
+
+  /**
+   * The destination of the access is a property getter/setter that is defined
+   * statically within a class, or at top level within a library.
+   */
+  static const AccessKind STATIC_PROPERTY =
+      const AccessKind._('STATIC_PROPERTY');
+
+  /**
+   * The destination of the access is a toplevel class, function typedef, mixin
+   * application, or the built-in type "dynamic".
+   */
+  static const AccessKind TOPLEVEL_TYPE = const AccessKind._('TOPLEVEL_TYPE');
+
+  /**
+   * The destination of the access is a type parameter of the enclosing class.
+   */
+  static const AccessKind TYPE_PARAMETER = const AccessKind._('TYPE_PARAMETER');
+
+  final String name;
+
+  const AccessKind._(this.name);
+
+  String toString() => name;
+}
+
+/**
+ * Data structure used to classify the semantics of a property access or method
+ * or function invocation.
+ */
+// TODO(paulberry,johnniwinther): Support index operations in AccessSemantics.
+class AccessSemantics {
+  /**
+   * The kind of access.
+   */
+  final AccessKind kind;
+
+  /**
+   * The name being used to access the property, method, or function.
+   */
+  final String name;
+
+  /**
+   * The element being accessed, if statically known.  This will be null if
+   * [kind] is DYNAMIC or if the element is undefined (e.g. an attempt to
+   * access a non-existent static method in a class).
+   */
+  final Element element;
+
+  /**
+   * The class containing the element being accessed, if this is a static
+   * reference to an element in a class.  This will be null if [kind] is
+   * DYNAMIC, LOCAL_FUNCTION, LOCAL_VARIABLE, PARAMETER, TOPLEVEL_CLASS, or
+   * TYPE_PARAMETER, or if the element being accessed is defined at toplevel
+   * within a library.
+   *
+   * Note: it is possible for [classElement] to be non-null and for [element]
+   * to be null; for example this occurs if the element being accessed is a
+   * non-existent static method or field inside an existing class.
+   */
+  final ClassElement classElement;
+
+  // TODO(paulberry): would it also be useful to store the libraryElement?
+
+  /**
+   * When [kind] is DYNAMIC, the expression whose runtime type determines the
+   * class in which [identifier] should be looked up.  Null if the expression
+   * is implicit "this".
+   *
+   * When [kind] is not DYNAMIC, this field is always null.
+   */
+  final /*Expression*/ target;
+
+  /**
+   * True if this is an invocation of a method, or a call on a property.
+   */
+  final bool isInvoke;
+
+  /**
+   * True if this is a read access to a property, or a method tear-off.  Note
+   * that both [isRead] and [isWrite] will be true in the case of a
+   * read-modify-write operation (e.g. "+=").
+   */
+  final bool isRead;// => !isInvoke && identifier.inGetterContext();
+
+  /**
+   * True if this is a write access to a property, or an (erroneous) attempt to
+   * write to a method.  Note that both [isRead] and [isWrite] will be true in
+   * the case of a read-modify-write operation (e.g. "+=").
+   */
+  final bool isWrite; // => identifier.inSetterContext();
+
+  AccessSemantics.dynamic(
+      this.name,
+      this.target,
+      {this.isInvoke: false,
+       this.isRead: false,
+       this.isWrite: false})
+      : kind = AccessKind.DYNAMIC,
+        element = null,
+        classElement = null;
+
+  AccessSemantics.localFunction(
+      this.name,
+      this.element,
+      {this.isInvoke: false,
+       this.isRead: false,
+       this.isWrite: false})
+      : kind = AccessKind.LOCAL_FUNCTION,
+        classElement = null,
+        target = null;
+
+  AccessSemantics.localVariable(
+      this.name,
+      this.element,
+      {this.isInvoke: false,
+       this.isRead: false,
+       this.isWrite: false})
+      : kind = AccessKind.LOCAL_VARIABLE,
+        classElement = null,
+        target = null;
+
+  AccessSemantics.parameter(
+      this.name,
+      this.element,
+      {this.isInvoke: false,
+       this.isRead: false,
+       this.isWrite: false})
+      : kind = AccessKind.PARAMETER,
+        classElement = null,
+        target = null;
+
+  AccessSemantics.staticField(
+      this.name,
+      this.element,
+      this.classElement,
+      {this.isInvoke: false,
+       this.isRead: false,
+       this.isWrite: false})
+      : kind = AccessKind.STATIC_FIELD,
+        target = null;
+
+  AccessSemantics.staticMethod(
+      this.name,
+      this.element,
+      this.classElement,
+      {this.isInvoke: false,
+       this.isRead: false,
+       this.isWrite: false})
+      : kind = AccessKind.STATIC_METHOD,
+        target = null;
+
+  AccessSemantics.staticProperty(
+      this.name,
+      this.element,
+      this.classElement,
+      {this.isInvoke: false,
+       this.isRead: false,
+       this.isWrite: false})
+      : kind = AccessKind.STATIC_PROPERTY,
+        target = null;
+
+  AccessSemantics.toplevelType(
+      this.name,
+      this.element,
+      {this.isInvoke: false,
+       this.isRead: false,
+       this.isWrite: false})
+      : kind = AccessKind.TOPLEVEL_TYPE,
+        classElement = null,
+        target = null;
+
+  AccessSemantics.typeParameter(
+      this.name,
+      this.element,
+      {this.isInvoke: false,
+       this.isRead: false,
+       this.isWrite: false})
+      : kind = AccessKind.TYPE_PARAMETER,
+        classElement = null,
+        target = null;
+
+  String toString() {
+    StringBuffer sb = new StringBuffer();
+    sb.write('AccessSemantics[');
+    sb.write('kind=$kind,');
+    if (isRead && isWrite) {
+      assert(!isInvoke);
+      sb.write('read/write,');
+    } else if (isRead) {
+      sb.write('read,');
+    } else if (isWrite) {
+      sb.write('write,');
+    } else if (isInvoke) {
+      sb.write('call,');
+    }
+    if (element != null) {
+      sb.write('element=');
+      if (classElement != null) {
+        sb.write('${classElement.name}.');
+      }
+      sb.write('${element}');
+    } else {
+      if (target == null) {
+        sb.write('target=this.$name');
+      } else {
+        sb.write('target=$target.$name');
+      }
+    }
+    sb.write(']');
+    return sb.toString();
+  }
+}