Implement canonical name scheme in kernel.

pkg/kernel/lib/canonical_name.dart

Index: pkg/kernel/lib/canonical_name.dart
diff --git a/pkg/kernel/lib/canonical_name.dart b/pkg/kernel/lib/canonical_name.dart
new file mode 100644
index 0000000000000000000000000000000000000000..7bf05dc4507ccf12ad724daf9d10de4e9a5a5f29
--- /dev/null
+++ b/pkg/kernel/lib/canonical_name.dart
@@ -0,0 +1,149 @@
+// Copyright (c) 2016, 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.
+library kernel.canonical_name;
+
+import 'ast.dart';
+
+/// A string sequence that identifies a library, class, or member.
+///
+/// Canonical names are organized in a prefix tree.  Each node knows its
+/// parent, children, and the AST node it is currently bound to.
+///
+/// The following schema specifies how the canonical name of a given object
+/// is defined:
+///
+///      Library:
+///         URI of library
+///
+///      Class:
+///         Canonical name of enclosing library
+///         Name of class
+///
+///      Constructor:
+///         Canonical name of enclosing class or library
+///         "@constructors"
+///         Qualified name
+///
+///      Field:
+///         Canonical name of enclosing class or library
+///         "@fields"
+///         Qualified name
+///
+///      Procedure that is not an accessor:
+///         Canonical name of enclosing class or library
+///         "@methods"
+///         Qualified name
+///
+///      Procedure that is a getter:
+///         Canonical name of enclosing class or library
+///         "@getters"
+///         Qualified name
+///
+///      Procedure that is a setter:
+///         Canonical name of enclosing class or library
+///         "@setters"
+///         Qualified name
+///
+///      Qualified name:
+///         if private: URI of library
+///         Name text
+///
+/// The "qualified name" allows a member to have a name that is private to
+/// a library other than the one containing that member.
+class CanonicalName {
+  final CanonicalName parent;
+  final String name;
+
+  Map<String, CanonicalName> _children;
+
+  /// The library, class, or member bound to this name.
+  Reference reference;
+
+  /// Temporary index used during serialization.
+  int index = -1;
+
+  CanonicalName._(this.parent, this.name) {
+    assert(name != null);
+  }
+
+  CanonicalName.root()
+      : parent = null,
+        name = '';
+
+  bool get isRoot => parent == null;
+
+  Iterable<CanonicalName> get children =>
+      _children?.values ?? const <CanonicalName>[];
+
+  CanonicalName getChild(String name) {
+    var map = _children ??= <String, CanonicalName>{};
+    return map[name] ??= new CanonicalName._(this, name);
+  }
+
+  CanonicalName getChildFromUri(Uri uri) {
+    // Note that the Uri class caches its string representation, and all library
+    // URIs will be stringified for serialization anyway, so there is no
+    // significant cost for converting the Uri to a string here.
+    return getChild('$uri');
+  }
+
+  CanonicalName getChildFromQualifiedName(Name name) {
+    return name.isPrivate
+        ? getChildFromUri(name.library.importUri).getChild(name.name)
+        : getChild(name.name);
+  }
+
+  CanonicalName getChildFromMember(Member member) {
+    return getChild(getMemberQualifier(member))
+        .getChildFromQualifiedName(member.name);
+  }
+
+  void bindTo(Reference target) {
+    if (reference == target) return;
+    if (reference != null) {
+      throw '$this is already bound';
+    }
+    if (target.canonicalName != null) {
+      throw 'Cannot bind $this to ${target.node}, target is already bound to '
+          '${target.canonicalName}';
+    }
+    target.canonicalName = this;
+    this.reference = target;
+  }
+
+  void unbind() {
+    if (reference == null) return;
+    assert(reference.canonicalName == this);
+    reference.canonicalName = null;
+    reference = null;
+  }
+
+  void unbindAll() {
+    unbind();
+    for (var child in children) {
+      child.unbindAll();
+    }
+  }
+
+  String toString() => parent == null ? 'root' : '$parent::$name';
+
+  Reference getReference() {
+    return reference ??= (new Reference()..canonicalName = this);
+  }
+
+  static String getMemberQualifier(Member member) {
+    if (member is Procedure) {
+      if (member.isGetter) return '@getters';
+      if (member.isSetter) return '@setters';
+      return '@methods';
+    }
+    if (member is Field) {
+      return '@fields';
+    }
+    if (member is Constructor) {
+      return '@constructors';
+    }
+    throw 'Unexpected member: $member';
+  }
+}