Fix cast_string_to_float with trailing whitespaces for inf and nan string

src/main/cpp/src/cast_string_to_float.cu

@@ -241,15 +241,24 @@ class string_to_float {
                                           (_warp_lane == 1 && (_c == 'A' || _c == 'a')) ||
                                           (_warp_lane == 2 && (_c == 'N' || _c == 'n')));
     if (nan_mask == 0x7) {
-      // if we start with 'nan', then even if we have other garbage character, this is a null row.
-      //
-      // if we're in ansi mode and this is not -precisely- nan, report that so that we can throw
-      // an exception later.
-      if (_len != 3) {
-        _valid  = false;
-        _except = _len != 3;
-      }
-      return true;
+      // if we start with 'nan', then even if we have other garbage character(excluding
+      // whitespaces), this is a null row. but for e.g. : "nan   " cases. spark will treat the as
+      // "nan", when the trailing characters are whitespaces, it is still a valid string. if we're
+      // in ansi mode and this is not -precisely- nan, report that so that we can throw an exception
+      // later.
+
+      // move forward the curren position by 3
+      _bpos += 3;
+      _c = __shfl_down_sync(0xffffffff, _c, 3);
+
+      // remove the trailing whitespaces, if there exits
+      remove_leading_whitespace();
+
+      // if we're at the end
+      if (_bpos == _len) { return true; }
+      // if we reach out here, it means that we have other garbage character.
+      _valid  = false;
+      _except = true;
     }
     return false;
   }
@@ -295,13 +304,21 @@ class string_to_float {
                                                  (_warp_lane == 4 && (_c == 'Y' || _c == 'y')));
       if (infinity_mask == 0x1f) {
         _bpos += 5;
+        _c = __shfl_down_sync(0xffffffff, _c, 5);
         // if we're at the end
         if (_bpos == _len) { return true; }
       }
 
+      // remove the remaining whitespace if exits
+      remove_leading_whitespace();
+
+      // if we're at the end
+      if (_bpos == _len) { return true; }
+
       // if we reach here for any reason, it means we have "inf" or "infinity" at the start of the
       // string but also have additional characters, making this whole thing bogus/null
       _valid = false;
+
       return true;
     }
     return false;

src/test/java/com/nvidia/spark/rapids/jni/CastStringsTest.java

@@ -59,6 +59,60 @@ void castToIntegerTest() {
     }
   }
 
+
+  //This is for testing the CastStrings class with the input of "inf" etc string
+  @Test
+  void castToFloatsInfTest(){
+    // The test data: Table.TestBuilder object with a column containing the string "inf"
+    Table.TestBuilder tb2 = new Table.TestBuilder();
+    tb2.column("INFINITY ", "inf", "+inf ", " -INF  ");
+
+    Table.TestBuilder tb = new Table.TestBuilder();
+    tb.column(Float.POSITIVE_INFINITY, Float.POSITIVE_INFINITY, Float.POSITIVE_INFINITY, Float.NEGATIVE_INFINITY);
+
+    try (Table expected = tb.build()) {
+      List<ColumnVector> result = new ArrayList<>();
+      try (Table origTable = tb2.build()) {
+        for (int i = 0; i < origTable.getNumberOfColumns(); i++) {
+          ColumnVector string_col = origTable.getColumn(i);
+          result.add(CastStrings.toFloat(string_col, false, expected.getColumn(i).getType()));
+        }
+        try (Table result_tbl = new Table(result.toArray(new ColumnVector[result.size()]))) {
+          AssertUtils.assertTablesAreEqual(expected, result_tbl);
+        }
+      } finally {
+        result.forEach(ColumnVector::close);
+      }
+    }
+  }
+
+  //This is for testing the CastStrings class with the input of "nan " etc string
+  @Test
+  void castToFloatNanTest(){
+    // The test data: Table.TestBuilder object with a column containing the string "inf"
+    Table.TestBuilder tb2 = new Table.TestBuilder();
+    tb2.column("nan", "nan ", " nan ", "NAN", "nAn ", " NAn ");
+
+    Table.TestBuilder tb = new Table.TestBuilder();
+    tb.column(Float.NaN, Float.NaN, Float.NaN, Float.NaN, Float.NaN, Float.NaN);
+
+    try (Table expected = tb.build()) {
+      List<ColumnVector> result = new ArrayList<>();
+      try (Table origTable = tb2.build()) {
+        for (int i = 0; i < origTable.getNumberOfColumns(); i++) {
+          ColumnVector string_col = origTable.getColumn(i);
+          result.add(CastStrings.toFloat(string_col, false, expected.getColumn(i).getType()));
+        }
+        try (Table result_tbl = new Table(result.toArray(new ColumnVector[result.size()]))) {
+          AssertUtils.assertTablesAreEqual(expected, result_tbl);
+        }
+      } finally {
+        result.forEach(ColumnVector::close);
+      }
+    }
+  }
+
+
   @Test
   void castToIntegerNoStripTest() {
     Table.TestBuilder tb = new Table.TestBuilder();