--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/backend/src/main/java/org/dive4elements/river/importer/ValueKey.java	Thu Apr 25 15:23:37 2013 +0200
@@ -0,0 +1,63 @@
+package org.dive4elements.river.importer;
+
+import java.math.BigDecimal;
+
+import java.util.Comparator;
+
+public class ValueKey
+{
+    public static final double EPSILON = 1e-6;
+
+    public static final Comparator<ValueKey> EPSILON_COMPARATOR =
+        new Comparator<ValueKey>()
+    {
+        public int compare(ValueKey x, ValueKey y) {
+            int cmp = ValueKey.compare(x.a, y.a);
+            if (cmp != 0) return cmp;
+            return ValueKey.compare(x.b, y.b);
+        }
+    };
+
+    public static int compare(BigDecimal a, BigDecimal b) {
+        if (a == null && b == null) return  0;
+        if (a != null && b == null) return +1;
+        if (a == null && b != null) return -1;
+
+        double diff = a.doubleValue() - b.doubleValue();
+        if (diff < -EPSILON) return -1;
+        return diff > EPSILON ? +1 : 0;
+    }
+
+    protected BigDecimal a;
+    protected BigDecimal b;
+
+    public ValueKey() {
+    }
+
+    public ValueKey(BigDecimal a, BigDecimal b) {
+        this.a = a;
+        this.b = b;
+    }
+
+    @Override
+    public int hashCode() {
+        return ((a != null ? a.hashCode() : 0) << 16)
+              | (b != null ? b.hashCode() : 0);
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        if (!(other instanceof ValueKey)) {
+            return false;
+        }
+        ValueKey o = (ValueKey)other;
+        return !(
+               (a == null && o.a != null)
+            || (a != null && o.a == null)
+            || (a != null && !a.equals(o.a))
+            || (b == null && o.b != null)
+            || (b != null && o.b == null)
+            || (b != null && !b.equals(o.b)));
+    }
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :