--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk.jshell/share/classes/jdk/jshell/KeyMap.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.jshell;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.stream.Stream;
+import jdk.jshell.Key.TypeDeclKey;
+import jdk.jshell.Key.ErroneousKey;
+import jdk.jshell.Key.ExpressionKey;
+import jdk.jshell.Key.ImportKey;
+import jdk.jshell.Key.MethodKey;
+import jdk.jshell.Key.StatementKey;
+import jdk.jshell.Key.VarKey;
+import jdk.jshell.Snippet.SubKind;
+import static jdk.jshell.Snippet.SubKind.SINGLE_STATIC_IMPORT_SUBKIND;
+import static jdk.jshell.Snippet.SubKind.SINGLE_TYPE_IMPORT_SUBKIND;
+
+/**
+ * Maps signature to Key by Kind.
+ * @author Robert Field
+ */
+class KeyMap {
+    private final JShell state;
+
+    KeyMap(JShell state) {
+        this.state = state;
+    }
+
+    private final Map<String, TypeDeclKey> classMap = new LinkedHashMap<>();
+    private final Map<String, MethodKey> methodMap = new LinkedHashMap<>();
+    private final Map<String, VarKey> varMap = new LinkedHashMap<>();
+    private final Map<String, ImportKey> importMap = new LinkedHashMap<>();
+
+    TypeDeclKey keyForClass(String name) {
+        return classMap.computeIfAbsent(name, k -> new TypeDeclKey(state, name));
+    }
+
+    MethodKey keyForMethod(String name, String parameterTypes) {
+        return methodMap.computeIfAbsent(name + ":" + parameterTypes,
+                                         k -> new MethodKey(state, name, parameterTypes));
+    }
+
+    VarKey keyForVariable(String name) {
+        return varMap.computeIfAbsent(name, k -> new VarKey(state, name));
+    }
+
+    ImportKey keyForImport(String name, SubKind snippetKind) {
+        return importMap.computeIfAbsent(name + ":"
+                + ((snippetKind == SINGLE_TYPE_IMPORT_SUBKIND || snippetKind == SINGLE_STATIC_IMPORT_SUBKIND)
+                        ? "single"
+                        : snippetKind.toString()),
+                k -> new ImportKey(state, name, snippetKind));
+    }
+
+    StatementKey keyForStatement() {
+        return new StatementKey(state);
+    }
+
+    ExpressionKey keyForExpression(String name, String type) {
+        return new ExpressionKey(state, name, type);
+    }
+
+    ErroneousKey keyForErroneous() {
+        return new ErroneousKey(state);
+    }
+
+    boolean doesVariableNameExist(String name) {
+        return varMap.get(name) != null;
+    }
+
+    Stream<ImportKey> importKeys() {
+        return importMap.values().stream();
+    }
+}