From e11bce7ad3e803e80883499fec0ad6e4540ffe43 Mon Sep 17 00:00:00 2001
From: Kristóf Marussy <marussy@mit.bme.hu>
Date: Tue, 30 Jun 2020 18:03:48 +0200
Subject: Add modified VIATRA-DSE version

---
 .../src/org/eclipse/viatra/dse/util/Hasher.java    | 86 ++++++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100644 Solvers/VIATRA-Solver/org.eclipse.viatra.dse/src/org/eclipse/viatra/dse/util/Hasher.java

(limited to 'Solvers/VIATRA-Solver/org.eclipse.viatra.dse/src/org/eclipse/viatra/dse/util/Hasher.java')

diff --git a/Solvers/VIATRA-Solver/org.eclipse.viatra.dse/src/org/eclipse/viatra/dse/util/Hasher.java b/Solvers/VIATRA-Solver/org.eclipse.viatra.dse/src/org/eclipse/viatra/dse/util/Hasher.java
new file mode 100644
index 00000000..0c5d7eba
--- /dev/null
+++ b/Solvers/VIATRA-Solver/org.eclipse.viatra.dse/src/org/eclipse/viatra/dse/util/Hasher.java
@@ -0,0 +1,86 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2014, Miklos Foldenyi, Andras Szabolcs Nagy, Abel Hegedus, Akos Horvath, Zoltan Ujhelyi and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package org.eclipse.viatra.dse.util;
+
+import java.math.BigInteger;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+
+import org.eclipse.viatra.dse.api.DSEException;
+
+/**
+ * Utility class that encapsulates a {@link MessageDigest} instance to aid calculating hash values more easily, and to
+ * reuse a {@link MessageDigest} instance.
+ * 
+ */
+public final class Hasher {
+    private MessageDigest md;
+
+    private static final int HEX = 16;
+
+    private Hasher(MessageDigest md) {
+        this.md = md;
+    }
+
+    /**
+     * Calculates and returns a hash value.
+     * 
+     * @param data
+     *            the data to be hashed in a {@link String}.
+     * @return the hash value in some {@link String} representation.
+     */
+    public String hash(String data) {
+        md.update(data.getBytes(), 0, data.length());
+        return new String(md.digest());
+    }
+
+    @SuppressWarnings("unused")
+    private String alternateHashBest(String data) {
+        md.update(data.getBytes(), 0, data.length());
+        return new String(md.digest());
+    }
+
+    @SuppressWarnings("unused")
+    private String alternateHashSecondBest(String data) {
+        md.update(data.getBytes(), 0, data.length());
+        return new BigInteger(1, md.digest()).toString(HEX);
+    }
+
+    @SuppressWarnings("unused")
+    private String alternateHashThirdBest(String data) {
+        md.update(data.getBytes(), 0, data.length());
+        byte[] array = md.digest();
+        StringBuilder sb = new StringBuilder();
+        for (int i = 0; i < array.length; i++) {
+            sb.append(Integer.toHexString((int) array[i]));
+        }
+        return sb.toString();
+    }
+
+    /**
+     * Returns a {@link Hasher} with an internal {@link MessageDigest} that is based on the protocol named
+     * {@code protocoll}.
+     * 
+     * @param protocoll
+     *            the name of the hash algorythm.
+     * @return the initialized {@link Hasher}
+     * 
+     * @throws DSEException
+     *             on initialization failure.
+     */
+    public static Hasher getHasher(String protocoll) {
+        try {
+            return new Hasher(MessageDigest.getInstance(protocoll));
+        } catch (NoSuchAlgorithmException e) {
+            throw new DSEException(e);
+        }
+    }
+
+    public static final String SHA1_PROTOCOLL = "SHA-1";
+}
-- 
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