Simple implementations for lazy values and memoized functions

2013-05-15 12:47:33 +04:00
parent c1cef019ce
commit 364ed19c4b
4 changed files with 174 additions and 0 deletions
@@ -0,0 +1,43 @@
+/*
+ * Copyright 2010-2013 JetBrains s.r.o.
+ *
+ * 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 org.jetbrains.jet.lang.resolve.lazy.storage;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Map;
+
+public abstract class MemoizedFunctionToNotNullImpl<K, V> extends MemoizedFunctionToNullableImpl<K, V> implements MemoizedFunctionToNotNull<K, V> {
+
+    public MemoizedFunctionToNotNullImpl() {
+    }
+
+    public MemoizedFunctionToNotNullImpl(@NotNull Map<K, Object> map) {
+        super(map);
+    }
+
+    @NotNull
+    @Override
+    public V fun(K input) {
+        V result = super.fun(input);
+        assert result != null : "compute() returned null";
+        return result;
+    }
+
+    @NotNull
+    @Override
+    protected abstract V doCompute(K input);
+}
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2010-2013 JetBrains s.r.o.
+ *
+ * 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 org.jetbrains.jet.lang.resolve.lazy.storage;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.jetbrains.jet.utils.WrappedValues;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public abstract class MemoizedFunctionToNullableImpl<K, V> implements MemoizedFunctionToNullable<K, V> {
+    private final Map<K, Object> cache;
+
+    public MemoizedFunctionToNullableImpl() {
+        this(new HashMap<K, Object>());
+    }
+
+    public MemoizedFunctionToNullableImpl(@NotNull Map<K, Object> map) {
+        this.cache = map;
+    }
+
+    @Nullable
+    @Override
+    public V fun(K input) {
+        Object value = cache.get(input);
+        if (value != null) return WrappedValues.unescapeNull(value);
+
+        V typedValue = doCompute(input);
+
+        Object oldValue = cache.put(input, WrappedValues.escapeNull(typedValue));
+        assert oldValue == null : "Race condition detected";
+
+        return typedValue;
+    }
+
+    @Nullable
+    protected abstract V doCompute(K input);
+}
@@ -0,0 +1,34 @@
+/*
+ * Copyright 2010-2013 JetBrains s.r.o.
+ *
+ * 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 org.jetbrains.jet.lang.resolve.lazy.storage;
+
+import org.jetbrains.annotations.NotNull;
+
+public abstract class NotNullLazyValueImpl<T> extends NullableLazyValueImpl<T> implements NotNullLazyValue<T> {
+
+    @NotNull
+    @Override
+    public T compute() {
+        T result = super.compute();
+        assert result != null : "compute() returned null";
+        return result;
+    }
+
+    @NotNull
+    @Override
+    protected abstract T doCompute();
+}
@@ -0,0 +1,44 @@
+/*
+ * Copyright 2010-2013 JetBrains s.r.o.
+ *
+ * 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 org.jetbrains.jet.lang.resolve.lazy.storage;
+
+import org.jetbrains.annotations.Nullable;
+import org.jetbrains.jet.utils.WrappedValues;
+
+public abstract class NullableLazyValueImpl<T> implements NullableLazyValue<T> {
+    @Nullable
+    private Object value = null;
+
+    @Override
+    public T compute() {
+        Object _value = value;
+        if (_value != null) return WrappedValues.unescapeNull(_value);
+
+        T typedValue = doCompute();
+        value = WrappedValues.escapeNull(typedValue);
+
+        postCompute(typedValue);
+
+        return typedValue;
+    }
+
+    protected abstract T doCompute();
+
+    protected void postCompute(T value) {
+        // Doing something in post-compute helps prevent infinite recursion
+    }
+}