Initialize gradle project

1 files changed, 155 insertions, 0 deletions

diff --git a/src/main/java/pl/edu/mimuw/cloudatlas/model/ValueNull.java b/src/main/java/pl/edu/mimuw/cloudatlas/model/ValueNull.java
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+/**
+ * Copyright (c) 2014, University of Warsaw
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are permitted
+ * provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this list of
+ * conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
+ * conditions and the following disclaimer in the documentation and/or other materials provided
+ * with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
+ * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package pl.edu.mimuw.cloudatlas.model;
+
+import pl.edu.mimuw.cloudatlas.model.Value;
+import pl.edu.mimuw.cloudatlas.model.ValueNull;
+
+/**
+ * A special null value of an unknown type. This class is a singleton.
+ *
+ * @see TypePrimitve#NULL
+ * @see Type#isCompatible(Value)
+ */
+public class ValueNull extends Value {
+    private static ValueNull instance = null;
+
+    private ValueNull() {}
+
+    /**
+     * Gets a singleton instance of the <code>ValueNull</code> class. Every call to this method returns the same
+     * reference.
+     *
+     * @return an instance of <code>ValueNull</code>
+     */
+    public static ValueNull getInstance() {
+        if(instance == null)
+            instance = new ValueNull();
+        return instance;
+    }
+
+    @Override
+    public Value getDefaultValue() {
+        return instance;
+    }
+
+    @Override
+    public Value convertTo(Type type) {
+        switch(type.getPrimaryType()) {
+            case STRING:
+                return ValueString.NULL_STRING;
+            default:
+                return this;
+        }
+    }
+
+    @Override
+    public Type getType() {
+        return TypePrimitive.NULL;
+    }
+
+    @Override
+    public boolean isNull() {
+        return true;
+    }
+
+    @Override
+    public Value isEqual(Value value) {
+        return new ValueBoolean(isNull() && value.isNull());
+    }
+
+    @Override
+    public Value isLowerThan(Value value) {
+        if(value == getInstance())
+            return this;
+        return value.isLowerThan(this);
+    }
+
+    @Override
+    public Value addValue(Value value) {
+        if(value == getInstance())
+            return this;
+        return value.addValue(this);
+    }
+
+    @Override
+    public Value subtract(Value value) {
+        if(value == getInstance())
+            return this;
+        return value.subtract(this);
+    }
+
+    @Override
+    public Value multiply(Value value) {
+        if(value == getInstance())
+            return this;
+        return value.multiply(this);
+    }
+
+    @Override
+    public Value divide(Value value) {
+        if(value == getInstance())
+            return this;
+        return value.divide(this);
+    }
+
+    @Override
+    public Value modulo(Value value) {
+        if(value == getInstance())
+            return this;
+        return value.modulo(this);
+    }
+
+    @Override
+    public Value and(Value value) {
+        if(value == getInstance())
+            return this;
+        return value.and(this);
+    }
+
+    @Override
+    public Value or(Value value) {
+        if(value == getInstance())
+            return this;
+        return value.or(this);
+    }
+
+    @Override
+    public Value regExpr(Value value) {
+        if(value == getInstance())
+            return this;
+        return value.regExpr(this);
+    }
+
+    @Override
+    public Value negate() {
+        return this;
+    }
+
+    @Override
+    public Value valueSize() {
+        return this;
+    }
+}