first commit

java/expression/Digits.java

@@ -0,0 +1,83 @@
+package expression;
+
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.util.List;
+
+/**
+ * @author Doschennikov Nikita (me@fymio.us)
+ */
+public class Digits extends AbstractExpression {
+
+    private final AbstractExpression operand;
+
+    public Digits(AbstractExpression operand) {
+        this.operand = operand;
+    }
+
+    private static int digitsSum(int n) {
+        if (n == 0) return 0;
+        boolean negative = n < 0;
+        long abs = Math.abs((long) n);
+        int sum = 0;
+        while (abs > 0) {
+            sum += (int) (abs % 10);
+            abs /= 10;
+        }
+        return negative ? -sum : sum;
+    }
+
+    @Override
+    public int evaluate(int x) {
+        return digitsSum(operand.evaluate(x));
+    }
+
+    @Override
+    public int evaluate(int x, int y, int z) {
+        return digitsSum(operand.evaluate(x, y, z));
+    }
+
+    @Override
+    public int evaluate(List<Integer> vars) {
+        return digitsSum(operand.evaluate(vars));
+    }
+
+    @Override
+    public BigInteger evaluateBi(List<BigInteger> vars) {
+        throw new UnsupportedOperationException(
+            "digits not supported for BigInteger"
+        );
+    }
+
+    @Override
+    public BigDecimal evaluateBd(List<BigDecimal> vars) {
+        throw new UnsupportedOperationException(
+            "digits not supported for BigDecimal"
+        );
+    }
+
+    @Override
+    public String toString() {
+        return "digits(" + operand + ")";
+    }
+
+    @Override
+    public String toMiniString() {
+        if (operand instanceof AbstractBinaryOperation) {
+            return "digits(" + operand.toMiniString() + ")";
+        }
+        return "digits " + operand.toMiniString();
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (!(obj instanceof Digits)) return false;
+        return operand.equals(((Digits) obj).operand);
+    }
+
+    @Override
+    public int hashCode() {
+        return operand.hashCode() ^ 0x44494754;
+    }
+}