Add value cache classes

src/main/java/ca/hss/math/ValueCache.java

@@ -0,0 +1,93 @@
+/**
+ * ValueCache.java
+ *
+ * Copyright 2022 Heartland Software Solutions Inc.
+ *
+ * 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 ca.hss.math;
+
+public class ValueCache<T1,T2> {
+	int		m_numEntries;
+	long	m_call;
+
+	static class Entry {
+		long	m_call = -1;
+		Object	m_key;
+		Object	m_value;
+	};
+
+	Entry [] entries = null;
+
+	public ValueCache(int numEntries) {
+		m_numEntries = numEntries;
+		entries = new Entry[m_numEntries];
+		for (int i = 0; i < m_numEntries; i++)
+			entries[i] = new Entry();
+	}
+
+	public void clear() {
+		for (int i = 0; i < m_numEntries; i++)
+			entries[i].m_call = -1;
+	}
+
+	public void put(T1 key, T2 value) {
+		if (m_numEntries == 0)
+			return;
+		m_call++;
+		if (m_call < 0) {
+			clear();
+			m_call++;
+		}
+
+		int i, oldest = 0;
+		for (i = 0; i < m_numEntries; i++) {
+			if (entries[i].m_call == -1)
+				break;
+			if (entries[i].m_call < entries[oldest].m_call)
+				oldest = i;
+			if (entries[i].m_key.equals(key)) {
+				entries[i].m_call = m_call;
+				return;
+			}
+		}
+		if (i == m_numEntries)
+			i = oldest;
+
+		entries[i].m_call = m_call;
+		entries[i].m_key = key;
+		entries[i].m_value = value;
+	}
+
+	@SuppressWarnings("unchecked")
+	public T2 get(T1 key) {
+		if (m_numEntries == 0)
+			return null;
+
+		for (int i = 0; i < m_numEntries; i++) {
+			if (entries[i].m_call == -1)
+				return null;
+			if (entries[i].m_key.equals(key)) {
+				m_call++;
+				if (m_call < 0) {
+					clear();
+					m_call++;
+				}
+				entries[i].m_call = m_call;
+				return (T2)entries[i].m_value;
+			}
+		}
+		return null;
+	}
+}

src/main/java/ca/hss/math/ValueCache_MT.java

@@ -0,0 +1,40 @@
+/**
+ * ValueCache_MT.java
+ *
+ * Copyright 2022 Heartland Software Solutions Inc.
+ *
+ * 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 ca.hss.math;
+
+public class ValueCache_MT<T1,T2> extends ValueCache<T1,T2> {
+	public ValueCache_MT(int numEntries) {
+		super(numEntries);
+	}
+
+	@Override
+	public synchronized void clear() {
+		super.clear();
+	}
+
+	@Override
+	public synchronized void put(T1 key, T2 value) {
+		super.put(key, value);
+	}
+
+	@Override
+	public synchronized T2 get(T1 key) {
+		return super.get(key);
+	}
+}