first commit

java/expression/Pow2.java

@@ -0,0 +1,47 @@
+package expression;
+
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.util.List;
+
+/**
+ * @author Doschennikov Nikita (me@fymio.us)
+ */
+public class Pow2 extends AbstractExpression {
+    private final AbstractExpression operand;
+
+    public Pow2(AbstractExpression operand) {
+        this.operand = operand;
+    }
+
+    private static int pow2(int n) {
+        if (n < 0) throw new ArithmeticException("pow₂ of negative number: " + n);
+        if (n >= 31) throw new OverflowException("pow₂");
+        return 1 << n;
+    }
+
+    @Override public int        evaluate(int x)               { return pow2(operand.evaluate(x)); }
+    @Override public int        evaluate(int x, int y, int z) { return pow2(operand.evaluate(x,y,z)); }
+    @Override public int        evaluate(List<Integer> vars)  { return pow2(operand.evaluate(vars)); }
+    @Override public BigInteger evaluateBi(List<BigInteger> vars) { throw new UnsupportedOperationException(); }
+    @Override public BigDecimal evaluateBd(List<BigDecimal> vars) { throw new UnsupportedOperationException(); }
+
+    @Override public String toString()     { return "pow₂(" + operand + ")"; }
+
+    @Override
+    public String toMiniString() {
+        if (operand instanceof AbstractBinaryOperation) {
+            return "pow₂(" + operand.toMiniString() + ")";
+        }
+        return "pow₂ " + operand.toMiniString();
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (!(obj instanceof Pow2)) return false;
+        return operand.equals(((Pow2) obj).operand);
+    }
+
+    @Override public int hashCode() { return operand.hashCode() ^ 0x504F5732; }
+}