Use ParameterizedMetricKeys again

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/oom/ClassStats.java

@@ -16,8 +16,6 @@ import net.sourceforge.pmd.lang.java.ast.ASTMethodOrConstructorDeclaration;
 import net.sourceforge.pmd.lang.java.ast.QualifiedName;
 import net.sourceforge.pmd.lang.java.oom.api.ClassMetric;
 import net.sourceforge.pmd.lang.java.oom.api.ClassMetricKey;
-import net.sourceforge.pmd.lang.java.oom.api.MemoKey;
-import net.sourceforge.pmd.lang.java.oom.api.Metric.Version;
 import net.sourceforge.pmd.lang.java.oom.api.MetricVersion;
 import net.sourceforge.pmd.lang.java.oom.api.OperationMetricKey;
 import net.sourceforge.pmd.lang.java.oom.api.ResultOption;
@@ -42,7 +40,7 @@ import net.sourceforge.pmd.lang.java.oom.signature.OperationSignature;
     private Map<FieldSignature, Set<String>> fields = new HashMap<>();
     private Map<String, ClassStats> nestedClasses = new HashMap<>();
 
-    private Map<MemoKey, Double> memo = new HashMap<>();
+    private Map<ParameterizedMetricKey, Double> memo = new HashMap<>();
 
     // References to the hierarchy
     // TODO:cf useful?
@@ -252,7 +250,7 @@ import net.sourceforge.pmd.lang.java.oom.signature.OperationSignature;
      */
     /* default */ double compute(ClassMetricKey key, ASTAnyTypeDeclaration node, boolean force, MetricVersion version) {
 
-        MemoKey paramKey = version == Version.STANDARD ? key : version;
+        ParameterizedMetricKey paramKey = ParameterizedMetricKey.build(key, version);
         // if memo.get(key) == null then the metric has never been computed. NaN is a valid value.
         Double prev = memo.get(paramKey);
         if (!force && prev != null) {

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/oom/OperationStats.java

@@ -8,8 +8,6 @@ import java.util.HashMap;
 import java.util.Map;
 
 import net.sourceforge.pmd.lang.java.ast.ASTMethodOrConstructorDeclaration;
-import net.sourceforge.pmd.lang.java.oom.api.MemoKey;
-import net.sourceforge.pmd.lang.java.oom.api.Metric.Version;
 import net.sourceforge.pmd.lang.java.oom.api.MetricVersion;
 import net.sourceforge.pmd.lang.java.oom.api.OperationMetric;
 import net.sourceforge.pmd.lang.java.oom.api.OperationMetricKey;
@@ -23,7 +21,7 @@ import net.sourceforge.pmd.lang.java.oom.api.OperationMetricKey;
 /* default */ class OperationStats {
 
     private final String name;
-    private final Map<MemoKey, Double> memo = new HashMap<>();
+    private final Map<ParameterizedMetricKey, Double> memo = new HashMap<>();
 
 
     /* default */ OperationStats(String name) {
@@ -48,7 +46,7 @@ import net.sourceforge.pmd.lang.java.oom.api.OperationMetricKey;
     /* default */ double compute(OperationMetricKey key, ASTMethodOrConstructorDeclaration node, boolean force,
                                  MetricVersion version) {
 
-        MemoKey paramKey = version == Version.STANDARD ? key : version;
+        ParameterizedMetricKey paramKey = ParameterizedMetricKey.build(key, version);
         Double prev = memo.get(paramKey);
         if (!force && prev != null) {
             return prev;

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/oom/ParameterizedMetricKey.java

@@ -0,0 +1,83 @@
+/**
+ * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
+ */
+
+package net.sourceforge.pmd.lang.java.oom;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import net.sourceforge.pmd.lang.java.oom.api.Metric;
+import net.sourceforge.pmd.lang.java.oom.api.MetricKey;
+import net.sourceforge.pmd.lang.java.oom.api.MetricVersion;
+
+/**
+ * Represents a key parameterized with its version. Used to index memoization maps.
+ *
+ * @author Clément Fournier
+ */
+public final class ParameterizedMetricKey {
+
+    private static final Map<Integer, ParameterizedMetricKey> POOL = new HashMap<>();
+
+    /** The metric key. */
+    public final MetricKey<? extends Metric> key;
+    /** The version of the metric. */
+    public final MetricVersion version;
+
+    /** Used internally by the pooler. */
+    private ParameterizedMetricKey(MetricKey<? extends Metric> key, MetricVersion version) {
+        this.key = key;
+        this.version = version;
+    }
+
+    /** Builds a parameterized metric key. */
+    public static ParameterizedMetricKey build(MetricKey<? extends Metric> key, MetricVersion version) {
+        int code = code(key, version);
+        ParameterizedMetricKey paramKey = POOL.get(code);
+        if (paramKey == null) {
+            POOL.put(code, new ParameterizedMetricKey(key, version));
+        }
+        return POOL.get(code);
+    }
+
+    /** Used by the pooler. */
+    private static int code(MetricKey key, MetricVersion version) {
+        int result = key.hashCode();
+        result = 31 * result + version.hashCode();
+        return result;
+    }
+
+
+    @Override
+    public String toString() {
+        return "ParameterizedMetricKey{"
+            + "key=" + key
+            + ", version=" + version
+            + '}';
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+
+        ParameterizedMetricKey that = (ParameterizedMetricKey) o;
+
+        if (!key.equals(that.key)) {
+            return false;
+        }
+        return version.equals(that.version);
+    }
+
+    @Override
+    public int hashCode() {
+        int result = key.hashCode();
+        result = 31 * result + version.hashCode();
+        return result;
+    }
+}

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/oom/api/MemoKey.java

@@ -1,15 +0,0 @@
-/**
- * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
- */
-
-package net.sourceforge.pmd.lang.java.oom.api;
-
-/**
- * Keys for the memoization maps. By default, MetricKeys are used, but if the version is not
- * {@link Metric.Version#STANDARD}, then the version is used instead. This is why versions cannot be shared across
- * metrics.
- *
- * @author Clément Fournier
- */
-public interface MemoKey {
-}

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/oom/api/MetricKey.java

@@ -9,7 +9,7 @@ package net.sourceforge.pmd.lang.java.oom.api;
  *
  * @param <T> Type of the metric to identify (ClassMetric or OperationMetric).
  */
-public interface MetricKey<T extends Metric> extends MemoKey {
+public interface MetricKey<T extends Metric> {
 
     /**
      * Returns the name of the metric.

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/oom/api/MetricVersion.java

@@ -13,7 +13,7 @@ package net.sourceforge.pmd.lang.java.oom.api;
  *
  * @author Clément Fournier
  */
-public interface MetricVersion extends MemoKey {
+public interface MetricVersion {
 
     /**
      * Returns the name of the version.