first commit

java/expression/exceptions/CheckedNegate.java

@@ -0,0 +1,44 @@
+package expression.exceptions;
+
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.util.List;
+
+import expression.*;
+
+/**
+ * @author Doschennikov Nikita (me@fymio.us)
+ */
+public class CheckedNegate extends AbstractExpression {
+    private final AbstractExpression operand;
+
+    public CheckedNegate(AbstractExpression operand) {
+        this.operand = operand;
+    }
+
+    private static int checkedNegate(int n) {
+        if (n == Integer.MIN_VALUE) throw new OverflowException("negation");
+        return -n;
+    }
+
+    @Override public int        evaluate(int x)               { return checkedNegate(operand.evaluate(x)); }
+    @Override public int        evaluate(int x, int y, int z) { return checkedNegate(operand.evaluate(x,y,z)); }
+    @Override public int        evaluate(List<Integer> vars)  { return checkedNegate(operand.evaluate(vars)); }
+    @Override public BigInteger evaluateBi(List<BigInteger> vars) { return operand.evaluateBi(vars).negate(); }
+    @Override public BigDecimal evaluateBd(List<BigDecimal> vars) { return operand.evaluateBd(vars).negate(); }
+
+    @Override public String toString()     { return "-(" + operand + ")"; }
+    @Override public String toMiniString() {
+        if (operand instanceof AbstractBinaryOperation) return "-(" + operand.toMiniString() + ")";
+        return "- " + operand.toMiniString();
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (!(obj instanceof CheckedNegate)) return false;
+        return operand.equals(((CheckedNegate) obj).operand);
+    }
+
+    @Override public int hashCode() { return -operand.hashCode(); }
+}