1 files changed, 89 insertions, 0 deletions
diff --git a/dexgen/src/com/android/dexgen/util/MutabilityControl.java b/dexgen/src/com/android/dexgen/util/MutabilityControl.java
new file mode 100644
index 0000000..b3ee691
--- /dev/null
+++ b/dexgen/src/com/android/dexgen/util/MutabilityControl.java
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2007 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.dexgen.util;
+
+/**
+ * Very simple base class that implements a flag to control the mutability
+ * of instances. This class just provides the flag and a utility to check
+ * and throw the right exception, but it is up to subclasses to place calls
+ * to the checker in all the right places.
+ */
+public class MutabilityControl {
+    /** whether this instance is mutable */
+    private boolean mutable;
+
+    /**
+     * Constructs an instance. It is initially mutable.
+     */
+    public MutabilityControl() {
+        mutable = true;
+    }
+
+    /**
+     * Constructs an instance, explicitly indicating the mutability.
+     *
+     * @param mutable {@code true} iff this instance is mutable
+     */
+    public MutabilityControl(boolean mutable) {
+        this.mutable = mutable;
+    }
+
+    /**
+     * Makes this instance immutable.
+     */
+    public void setImmutable() {
+        mutable = false;
+    }
+
+    /**
+     * Checks to see whether or not this instance is immutable. This is the
+     * same as calling {@code !isMutable()}.
+     *
+     * @return {@code true} iff this instance is immutable
+     */
+    public final boolean isImmutable() {
+        return !mutable;
+    }
+
+    /**
+     * Checks to see whether or not this instance is mutable.
+     *
+     * @return {@code true} iff this instance is mutable
+     */
+    public final boolean isMutable() {
+        return mutable;
+    }
+
+    /**
+     * Throws {@link MutabilityException} if this instance is
+     * immutable.
+     */
+    public final void throwIfImmutable() {
+        if (!mutable) {
+            throw new MutabilityException("immutable instance");
+        }
+    }
+
+    /**
+     * Throws {@link MutabilityException} if this instance is mutable.
+     */
+    public final void throwIfMutable() {
+        if (mutable) {
+            throw new MutabilityException("mutable instance");
+        }
+    }
+}