Fix the edge case when handling non numeric values of double type in …

…delta stats

When reading the delta snapshot and load the information into Delta object AddFile, the non-numeric values of float or double type (example, "NaN", "-Infinity") from col stats become string type.
These special values need special handling and see how delta handled: https://github.com/delta-io/delta/blob/master/kernel/kernel-defaults/src/main/java/io/delta/kernel/defaults/internal/data/DefaultJsonRow.java#L210

xtable-core/src/main/java/org/apache/xtable/delta/DeltaValueConverter.java

@@ -44,6 +44,12 @@
 public class DeltaValueConverter {
   private static final String DATE_FORMAT_STR = "yyyy-MM-dd HH:mm:ss";
   private static final TimeZone TIME_ZONE = TimeZone.getTimeZone("UTC");
+  protected static final String NAN_VALUE = "NaN";
+  protected static final String INFINITY_VALUE = "Infinity";
+  protected static final String POSITIVE_INFINITY_VALUE = "+Infinity";
+  protected static final String POSITIVE_INF_VALUE = "+INF";
+  protected static final String NEGATIVE_INFINITY_VALUE = "-Infinity";
+  protected static final String NEGATIVE_INF_VALUE = "-INF";
 
   static DateFormat getDateFormat(String dataFormatString) {
     DateFormat dateFormat = new SimpleDateFormat(dataFormatString);
@@ -194,9 +200,35 @@ public static Object convertFromDeltaPartitionValue(
 
   private static Object castObjectToInternalType(Object value, InternalType valueType) {
     switch (valueType) {
+      case DOUBLE:
+        if (value instanceof String)
+          switch (value.toString()) {
+            case NAN_VALUE:
+              return Double.NaN;
+            case POSITIVE_INF_VALUE:
+            case POSITIVE_INFINITY_VALUE:
+            case INFINITY_VALUE:
+              return Double.POSITIVE_INFINITY;
+            case NEGATIVE_INF_VALUE:
+            case NEGATIVE_INFINITY_VALUE:
+              return Double.NEGATIVE_INFINITY;
+          }
+        break;
       case FLOAT:
         if (value instanceof Double) {
           return ((Double) value).floatValue();
+        } else if (value instanceof String) {
+          switch (value.toString()) {
+            case NAN_VALUE:
+              return Float.NaN;
+            case POSITIVE_INF_VALUE:
+            case POSITIVE_INFINITY_VALUE:
+            case INFINITY_VALUE:
+              return Float.POSITIVE_INFINITY;
+            case NEGATIVE_INF_VALUE:
+            case NEGATIVE_INFINITY_VALUE:
+              return Float.NEGATIVE_INFINITY;
+          }
         }
         break;
       case DECIMAL:

xtable-core/src/test/java/org/apache/xtable/delta/TestDeltaValueConverter.java

@@ -82,6 +82,15 @@ void parseWrongDateTime() throws ParseException {
     assertThrows(ParseException.class, () -> strictDateFormat.parse(wrongDateTime));
   }
 
+  @ParameterizedTest
+  @MethodSource("nonNumericValuesForColStats")
+  void formattedDifferentNonNumericValuesFromDeltaColumnStat(
+      Object fieldValue, InternalSchema fieldSchema, Object expectedDeltaValue) {
+    Object internalRepresentation =
+        DeltaValueConverter.convertFromDeltaColumnStatValue(fieldValue, fieldSchema);
+    assertEquals(internalRepresentation, expectedDeltaValue);
+  }
+
   private static Stream<Arguments> valuesWithSchemaProviderForColStats() {
     return Stream.of(
         Arguments.of(
@@ -187,4 +196,22 @@ private static Stream<Arguments> valuesWithSchemaProviderForPartitions() {
             "yyyy",
             "2022"));
   }
+
+  private static Stream<Arguments> nonNumericValuesForColStats() {
+    InternalSchema doubleSchema =
+        InternalSchema.builder().name("double").dataType(InternalType.DOUBLE).build();
+    InternalSchema floatSchema =
+        InternalSchema.builder().name("float").dataType(InternalType.FLOAT).build();
+    return Stream.of(
+        Arguments.of("NaN", doubleSchema, Double.NaN),
+        Arguments.of("Infinity", doubleSchema, Double.POSITIVE_INFINITY),
+        Arguments.of("-Infinity", doubleSchema, Double.NEGATIVE_INFINITY),
+        Arguments.of("+Infinity", doubleSchema, Double.POSITIVE_INFINITY),
+        Arguments.of("NaN", floatSchema, Float.NaN),
+        Arguments.of("Infinity", floatSchema, Float.POSITIVE_INFINITY),
+        Arguments.of("-Infinity", floatSchema, Float.NEGATIVE_INFINITY),
+        Arguments.of("+Infinity", floatSchema, Float.POSITIVE_INFINITY),
+        Arguments.of(Double.NaN, doubleSchema, Double.NaN),
+        Arguments.of(Double.POSITIVE_INFINITY, doubleSchema, Double.POSITIVE_INFINITY));
+  }
 }