Add intermediate VmResourceRef for inaccurate source lookup

plugins/org.chromium.debug.core/src/org/chromium/debug/core/model/VmResourceRef.java

Index: plugins/org.chromium.debug.core/src/org/chromium/debug/core/model/VmResourceRef.java
diff --git a/plugins/org.chromium.debug.core/src/org/chromium/debug/core/model/VmResourceRef.java b/plugins/org.chromium.debug.core/src/org/chromium/debug/core/model/VmResourceRef.java
new file mode 100644
index 0000000000000000000000000000000000000000..87e7d01f0d9f980a95b1cb78f8a6d4fd3da83bd4
--- /dev/null
+++ b/plugins/org.chromium.debug.core/src/org/chromium/debug/core/model/VmResourceRef.java
@@ -0,0 +1,56 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.debug.core.model;
+
+/**
+ * VM resource reference. It differs from {@link VmResourceId} in that it may be much less
+ * precise, e.g. RegExp over script name.
+ * {@link VmResourceRef} is an intermediate value derived from user IDE file and used for
+ * locating actual resource locally or on remote VM (when setting a breakpoint).
+ * This is an algebraic type. See {@link Visitor} and factory methods for details.
+ */
+public abstract class VmResourceRef {
+
+  /**
+   * A GoF Visitor interface for algebraic type {@link VmResourceRef}.
+   */
+  public interface Visitor<R> {
+    R visitResourceId(VmResourceId resourceId);
+  }
+
+  /**
+   * Creates VmResourceRef that is based on {@link VmResourceId}.
+   */
+  public static VmResourceRef forVmResourceId(VmResourceId vmResourceId) {
+    return new ForVmResourceId(vmResourceId);
+  }
+
+  private static final class ForVmResourceId extends VmResourceRef {
+    private final VmResourceId vmResourceId;
+
+    ForVmResourceId(VmResourceId vmResourceId) {
+      this.vmResourceId = vmResourceId;
+    }
+
+    @Override public <R> R accept(Visitor<R> visitor) {
+      return visitor.visitResourceId(vmResourceId);
+    }
+    @Override
+    public boolean equals(Object obj) {
+      if (obj == null || obj.getClass() != this.getClass()) {
+        return false;
+      }
+      ForVmResourceId that = (ForVmResourceId) obj;
+      return this.vmResourceId.equals(that.vmResourceId);
+    }
+
+    @Override
+    public int hashCode() {
+      return vmResourceId.hashCode();
+    }
+  }
+
+  public abstract <R> R accept(Visitor<R> visitor);
+}