[SPARK-27768][SQL] Support Infinity/NaN-related float/double literals case-insensitively

## What changes were proposed in this pull request?
Here is the problem description from the JIRA.
```
When the inputs contain the constant 'infinity', Spark SQL does not generate the expected results.

SELECT avg(CAST(x AS DOUBLE)), var_pop(CAST(x AS DOUBLE))
FROM (VALUES ('1'), (CAST('infinity' AS DOUBLE))) v(x);
SELECT avg(CAST(x AS DOUBLE)), var_pop(CAST(x AS DOUBLE))
FROM (VALUES ('infinity'), ('1')) v(x);
SELECT avg(CAST(x AS DOUBLE)), var_pop(CAST(x AS DOUBLE))
FROM (VALUES ('infinity'), ('infinity')) v(x);
SELECT avg(CAST(x AS DOUBLE)), var_pop(CAST(x AS DOUBLE))
FROM (VALUES ('-infinity'), ('infinity')) v(x);
 The root cause: Spark SQL does not recognize the special constants in a case insensitive way. In PostgreSQL, they are recognized in a case insensitive way.

Link: https://www.postgresql.org/docs/9.3/datatype-numeric.html
```

In this PR, the casting code is enhanced to handle these `special` string literals in case insensitive manner.

## How was this patch tested?
Added tests in CastSuite and modified existing test suites.

Closes #25331 from dilipbiswal/double_infinity.

Authored-by: Dilip Biswal <dbiswal@us.ibm.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>

docs/sql-migration-guide-upgrade.md

@@ -161,6 +161,95 @@ license: |
 
   - Since Spark 3.0, Dataset query fails if it contains ambiguous column reference that is caused by self join. A typical example: `val df1 = ...; val df2 = df1.filter(...);`, then `df1.join(df2, df1("a") > df2("a"))` returns an empty result which is quite confusing. This is because Spark cannot resolve Dataset column references that point to tables being self joined, and `df1("a")` is exactly the same as `df2("a")` in Spark. To restore the behavior before Spark 3.0, you can set `spark.sql.analyzer.failAmbiguousSelfJoin` to `false`.
 
+  - Since Spark 3.0, `Cast` function processes string literals such as 'Infinity', '+Infinity', '-Infinity', 'NaN', 'Inf', '+Inf', '-Inf' in case insensitive manner when casting the literals to `Double` or `Float` type to ensure greater compatibility with other database systems. This behaviour change is illustrated in the table below:
+    <table class="table">
+        <tr>
+          <th>
+            <b>Operation</b>
+          </th>
+          <th>
+            <b>Result prior to Spark 3.0</b>
+          </th>
+          <th>
+            <b>Result starting Spark 3.0</b>
+          </th>
+        </tr>
+        <tr>
+          <td>
+            CAST('infinity' AS DOUBLE)<br>
+            CAST('+infinity' AS DOUBLE)<br>
+            CAST('inf' AS DOUBLE)<br>
+            CAST('+inf' AS DOUBLE)<br>
+          </td>
+          <td>
+            NULL
+          </td>
+          <td>
+            Double.PositiveInfinity
+          </td>
+        </tr>
+        <tr>
+          <td>
+            CAST('-infinity' AS DOUBLE)<br>
+            CAST('-inf' AS DOUBLE)<br>
+          </td>
+          <td>
+            NULL
+          </td>
+          <td>
+            Double.NegativeInfinity
+          </td>
+        </tr>
+        <tr>
+          <td>
+            CAST('infinity' AS FLOAT)<br>
+            CAST('+infinity' AS FLOAT)<br>
+            CAST('inf' AS FLOAT)<br>
+            CAST('+inf' AS FLOAT)<br>
+          </td>
+          <td>
+            NULL
+          </td>
+          <td>
+            Float.PositiveInfinity
+          </td>
+        </tr>
+        <tr>
+          <td>
+            CAST('-infinity' AS FLOAT)<br>
+            CAST('-inf' AS FLOAT)<br>
+          </td>
+          <td>
+            NULL
+          </td>
+          <td>
+            Float.NegativeInfinity
+          </td>
+        </tr>
+        <tr>
+          <td>
+            CAST('nan' AS DOUBLE)
+          </td>
+          <td>
+            NULL
+          </td>
+          <td>
+            Double.NaN
+          </td>
+        </tr>
+        <tr>
+          <td>
+            CAST('nan' AS FLOAT)
+          </td>
+          <td>
+            NULL
+          </td>
+          <td>
+            Float.NaN
+          </td>
+        </tr>
+    </table>
+
 ## Upgrading from Spark SQL 2.4 to 2.4.1
 
   - The value of `spark.executor.heartbeatInterval`, when specified without units like "30" rather than "30s", was

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Cast.scala

@@ -19,6 +19,7 @@ package org.apache.spark.sql.catalyst.expressions
 
 import java.math.{BigDecimal => JavaBigDecimal}
 import java.time.ZoneId
+import java.util.Locale
 import java.util.concurrent.TimeUnit._
 
 import org.apache.spark.SparkException
@@ -193,6 +194,22 @@ object Cast {
   }
 
   def resolvableNullability(from: Boolean, to: Boolean): Boolean = !from || to
+
+  /**
+   * We process literals such as 'Infinity', 'Inf', '-Infinity' and 'NaN' etc in case
+   * insensitive manner to be compatible with other database systems such as PostgreSQL and DB2.
+   */
+  def processFloatingPointSpecialLiterals(v: String, isFloat: Boolean): Any = {
+    v.trim.toLowerCase(Locale.ROOT) match {
+      case "inf" | "+inf" | "infinity" | "+infinity" =>
+        if (isFloat) Float.PositiveInfinity else Double.PositiveInfinity
+      case "-inf" | "-infinity" =>
+        if (isFloat) Float.NegativeInfinity else Double.NegativeInfinity
+      case "nan" =>
+        if (isFloat) Float.NaN else Double.NaN
+      case _ => null
+    }
+  }
 }
 
 /**
@@ -563,8 +580,12 @@ case class Cast(child: Expression, dataType: DataType, timeZoneId: Option[String
   // DoubleConverter
   private[this] def castToDouble(from: DataType): Any => Any = from match {
     case StringType =>
-      buildCast[UTF8String](_, s => try s.toString.toDouble catch {
-        case _: NumberFormatException => null
+      buildCast[UTF8String](_, s => {
+        val doubleStr = s.toString
+        try doubleStr.toDouble catch {
+          case _: NumberFormatException =>
+            Cast.processFloatingPointSpecialLiterals(doubleStr, false)
+        }
       })
     case BooleanType =>
       buildCast[Boolean](_, b => if (b) 1d else 0d)
@@ -579,8 +600,12 @@ case class Cast(child: Expression, dataType: DataType, timeZoneId: Option[String
   // FloatConverter
   private[this] def castToFloat(from: DataType): Any => Any = from match {
     case StringType =>
-      buildCast[UTF8String](_, s => try s.toString.toFloat catch {
-        case _: NumberFormatException => null
+      buildCast[UTF8String](_, s => {
+        val floatStr = s.toString
+        try floatStr.toFloat catch {
+          case _: NumberFormatException =>
+            Cast.processFloatingPointSpecialLiterals(floatStr, true)
+        }
       })
     case BooleanType =>
       buildCast[Boolean](_, b => if (b) 1f else 0f)
@@ -718,9 +743,9 @@ case class Cast(child: Expression, dataType: DataType, timeZoneId: Option[String
     case ByteType => castToByteCode(from, ctx)
     case ShortType => castToShortCode(from, ctx)
     case IntegerType => castToIntCode(from, ctx)
-    case FloatType => castToFloatCode(from)
+    case FloatType => castToFloatCode(from, ctx)
     case LongType => castToLongCode(from, ctx)
-    case DoubleType => castToDoubleCode(from)
+    case DoubleType => castToDoubleCode(from, ctx)
 
     case array: ArrayType =>
       castArrayCode(from.asInstanceOf[ArrayType].elementType, array.elementType, ctx)
@@ -1260,48 +1285,66 @@ case class Cast(child: Expression, dataType: DataType, timeZoneId: Option[String
       (c, evPrim, evNull) => code"$evPrim = (long) $c;"
   }
 
-  private[this] def castToFloatCode(from: DataType): CastFunction = from match {
-    case StringType =>
-      (c, evPrim, evNull) =>
-        code"""
+  private[this] def castToFloatCode(from: DataType, ctx: CodegenContext): CastFunction = {
+    from match {
+      case StringType =>
+        val floatStr = ctx.freshVariable("floatStr", StringType)
+        (c, evPrim, evNull) =>
+          code"""
+          final String $floatStr = $c.toString();
           try {
-            $evPrim = Float.valueOf($c.toString());
+            $evPrim = Float.valueOf($floatStr);
           } catch (java.lang.NumberFormatException e) {
-            $evNull = true;
+            final Float f = (Float) Cast.processFloatingPointSpecialLiterals($floatStr, true);
+            if (f == null) {
+              $evNull = true;
+            } else {
+              $evPrim = f.floatValue();
+            }
           }
         """
-    case BooleanType =>
-      (c, evPrim, evNull) => code"$evPrim = $c ? 1.0f : 0.0f;"
-    case DateType =>
-      (c, evPrim, evNull) => code"$evNull = true;"
-    case TimestampType =>
-      (c, evPrim, evNull) => code"$evPrim = (float) (${timestampToDoubleCode(c)});"
-    case DecimalType() =>
-      (c, evPrim, evNull) => code"$evPrim = $c.toFloat();"
-    case x: NumericType =>
-      (c, evPrim, evNull) => code"$evPrim = (float) $c;"
+      case BooleanType =>
+        (c, evPrim, evNull) => code"$evPrim = $c ? 1.0f : 0.0f;"
+      case DateType =>
+        (c, evPrim, evNull) => code"$evNull = true;"
+      case TimestampType =>
+        (c, evPrim, evNull) => code"$evPrim = (float) (${timestampToDoubleCode(c)});"
+      case DecimalType() =>
+        (c, evPrim, evNull) => code"$evPrim = $c.toFloat();"
+      case x: NumericType =>
+        (c, evPrim, evNull) => code"$evPrim = (float) $c;"
+    }
   }
 
-  private[this] def castToDoubleCode(from: DataType): CastFunction = from match {
-    case StringType =>
-      (c, evPrim, evNull) =>
-        code"""
+  private[this] def castToDoubleCode(from: DataType, ctx: CodegenContext): CastFunction = {
+    from match {
+      case StringType =>
+        val doubleStr = ctx.freshVariable("doubleStr", StringType)
+        (c, evPrim, evNull) =>
+          code"""
+          final String $doubleStr = $c.toString();
           try {
-            $evPrim = Double.valueOf($c.toString());
+            $evPrim = Double.valueOf($doubleStr);
           } catch (java.lang.NumberFormatException e) {
-            $evNull = true;
+            final Double d = (Double) Cast.processFloatingPointSpecialLiterals($doubleStr, false);
+            if (d == null) {
+              $evNull = true;
+            } else {
+              $evPrim = d.doubleValue();
+            }
           }
         """
-    case BooleanType =>
-      (c, evPrim, evNull) => code"$evPrim = $c ? 1.0d : 0.0d;"
-    case DateType =>
-      (c, evPrim, evNull) => code"$evNull = true;"
-    case TimestampType =>
-      (c, evPrim, evNull) => code"$evPrim = ${timestampToDoubleCode(c)};"
-    case DecimalType() =>
-      (c, evPrim, evNull) => code"$evPrim = $c.toDouble();"
-    case x: NumericType =>
-      (c, evPrim, evNull) => code"$evPrim = (double) $c;"
+      case BooleanType =>
+        (c, evPrim, evNull) => code"$evPrim = $c ? 1.0d : 0.0d;"
+      case DateType =>
+        (c, evPrim, evNull) => code"$evNull = true;"
+      case TimestampType =>
+        (c, evPrim, evNull) => code"$evPrim = ${timestampToDoubleCode(c)};"
+      case DecimalType() =>
+        (c, evPrim, evNull) => code"$evPrim = $c.toDouble();"
+      case x: NumericType =>
+        (c, evPrim, evNull) => code"$evPrim = (double) $c;"
+    }
   }
 
   private[this] def castArrayCode(

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CastSuite.scala

@@ -1049,4 +1049,30 @@ class CastSuite extends SparkFunSuite with ExpressionEvalHelper {
         Cast(Literal(134.12), DecimalType(3, 2)), "cannot be represented")
     }
   }
+
+  test("Process Infinity, -Infinity, NaN in case insensitive manner") {
+    Seq("inf", "+inf", "infinity", "+infiNity", " infinity ").foreach { value =>
+      checkEvaluation(cast(value, FloatType), Float.PositiveInfinity)
+    }
+    Seq("-infinity", "-infiniTy", "  -infinity  ", "  -inf  ").foreach { value =>
+      checkEvaluation(cast(value, FloatType), Float.NegativeInfinity)
+    }
+    Seq("inf", "+inf", "infinity", "+infiNity", " infinity ").foreach { value =>
+      checkEvaluation(cast(value, DoubleType), Double.PositiveInfinity)
+    }
+    Seq("-infinity", "-infiniTy", "  -infinity  ", "  -inf  ").foreach { value =>
+      checkEvaluation(cast(value, DoubleType), Double.NegativeInfinity)
+    }
+    Seq("nan", "nAn", " nan ").foreach { value =>
+      checkEvaluation(cast(value, FloatType), Float.NaN)
+    }
+    Seq("nan", "nAn", " nan ").foreach { value =>
+      checkEvaluation(cast(value, DoubleType), Double.NaN)
+    }
+
+    // Invalid literals when casted to double and float results in null.
+    Seq(DoubleType, FloatType).foreach { dataType =>
+      checkEvaluation(cast("badvalue", dataType), null)
+    }
+  }
 }

sql/core/src/test/resources/sql-tests/inputs/pgSQL/aggregates_part1.sql

@@ -59,16 +59,14 @@ select avg(CAST(null AS DOUBLE)) from range(1,4);
 select sum(CAST('NaN' AS DOUBLE)) from range(1,4);
 select avg(CAST('NaN' AS DOUBLE)) from range(1,4);
 
--- [SPARK-27768] verify correct results for infinite inputs
 SELECT avg(CAST(x AS DOUBLE)), var_pop(CAST(x AS DOUBLE))
-FROM (VALUES (CAST('1' AS DOUBLE)), (CAST('Infinity' AS DOUBLE))) v(x);
+FROM (VALUES (CAST('1' AS DOUBLE)), (CAST('infinity' AS DOUBLE))) v(x);
 SELECT avg(CAST(x AS DOUBLE)), var_pop(CAST(x AS DOUBLE))
-FROM (VALUES ('Infinity'), ('1')) v(x);
+FROM (VALUES ('infinity'), ('1')) v(x);
 SELECT avg(CAST(x AS DOUBLE)), var_pop(CAST(x AS DOUBLE))
-FROM (VALUES ('Infinity'), ('Infinity')) v(x);
+FROM (VALUES ('infinity'), ('infinity')) v(x);
 SELECT avg(CAST(x AS DOUBLE)), var_pop(CAST(x AS DOUBLE))
-FROM (VALUES ('-Infinity'), ('Infinity')) v(x);
-
+FROM (VALUES ('-infinity'), ('infinity')) v(x);
 
 -- test accuracy with a large input offset
 SELECT avg(CAST(x AS DOUBLE)), var_pop(CAST(x AS DOUBLE))

sql/core/src/test/resources/sql-tests/inputs/pgSQL/float4.sql

@@ -38,7 +38,6 @@ INSERT INTO FLOAT4_TBL VALUES ('1.2345678901234e-20');
 
 -- special inputs
 SELECT float('NaN');
--- [SPARK-28060] Float type can not accept some special inputs
 SELECT float('nan');
 SELECT float('   NAN  ');
 SELECT float('infinity');
@@ -49,7 +48,6 @@ SELECT float('N A N');
 SELECT float('NaN x');
 SELECT float(' INFINITY    x');
 
--- [SPARK-28060] Float type can not accept some special inputs
 SELECT float('Infinity') + 100.0;
 SELECT float('Infinity') / float('Infinity');
 SELECT float('nan') / float('nan');

sql/core/src/test/resources/sql-tests/inputs/pgSQL/float8.sql

@@ -37,7 +37,6 @@ SELECT double('-10e-400');
 
 -- special inputs
 SELECT double('NaN');
--- [SPARK-28060] Double type can not accept some special inputs
 SELECT double('nan');
 SELECT double('   NAN  ');
 SELECT double('infinity');
@@ -49,7 +48,6 @@ SELECT double('NaN x');
 SELECT double(' INFINITY    x');
 
 SELECT double('Infinity') + 100.0;
--- [SPARK-27768] Infinity, -Infinity, NaN should be recognized in a case insensitive manner
 SELECT double('Infinity') / double('Infinity');
 SELECT double('NaN') / double('NaN');
 -- [SPARK-28315] Decimal can not accept NaN as input
@@ -190,7 +188,7 @@ SELECT tanh(double('1'));
 SELECT asinh(double('1'));
 SELECT acosh(double('2'));
 SELECT atanh(double('0.5'));
--- [SPARK-27768] Infinity, -Infinity, NaN should be recognized in a case insensitive manner
+
 -- test Inf/NaN cases for hyperbolic functions
 SELECT sinh(double('Infinity'));
 SELECT sinh(double('-Infinity'));

sql/core/src/test/resources/sql-tests/results/pgSQL/aggregates_part1.sql.out

@@ -236,7 +236,7 @@ NaN
 
 -- !query 29
 SELECT avg(CAST(x AS DOUBLE)), var_pop(CAST(x AS DOUBLE))
-FROM (VALUES (CAST('1' AS DOUBLE)), (CAST('Infinity' AS DOUBLE))) v(x)
+FROM (VALUES (CAST('1' AS DOUBLE)), (CAST('infinity' AS DOUBLE))) v(x)
 -- !query 29 schema
 struct<avg(CAST(x AS DOUBLE)):double,var_pop(CAST(x AS DOUBLE)):double>
 -- !query 29 output
@@ -245,7 +245,7 @@ Infinity	NaN
 
 -- !query 30
 SELECT avg(CAST(x AS DOUBLE)), var_pop(CAST(x AS DOUBLE))
-FROM (VALUES ('Infinity'), ('1')) v(x)
+FROM (VALUES ('infinity'), ('1')) v(x)
 -- !query 30 schema
 struct<avg(CAST(x AS DOUBLE)):double,var_pop(CAST(x AS DOUBLE)):double>
 -- !query 30 output
@@ -254,7 +254,7 @@ Infinity	NaN
 
 -- !query 31
 SELECT avg(CAST(x AS DOUBLE)), var_pop(CAST(x AS DOUBLE))
-FROM (VALUES ('Infinity'), ('Infinity')) v(x)
+FROM (VALUES ('infinity'), ('infinity')) v(x)
 -- !query 31 schema
 struct<avg(CAST(x AS DOUBLE)):double,var_pop(CAST(x AS DOUBLE)):double>
 -- !query 31 output
@@ -263,7 +263,7 @@ Infinity	NaN
 
 -- !query 32
 SELECT avg(CAST(x AS DOUBLE)), var_pop(CAST(x AS DOUBLE))
-FROM (VALUES ('-Infinity'), ('Infinity')) v(x)
+FROM (VALUES ('-infinity'), ('infinity')) v(x)
 -- !query 32 schema
 struct<avg(CAST(x AS DOUBLE)):double,var_pop(CAST(x AS DOUBLE)):double>
 -- !query 32 output

sql/core/src/test/resources/sql-tests/results/pgSQL/float4.sql.out

@@ -63,7 +63,7 @@ SELECT float('nan')
 -- !query 7 schema
 struct<CAST(nan AS FLOAT):float>
 -- !query 7 output
-NULL
+NaN
 
 
 -- !query 8
@@ -71,7 +71,7 @@ SELECT float('   NAN  ')
 -- !query 8 schema
 struct<CAST(   NAN   AS FLOAT):float>
 -- !query 8 output
-NULL
+NaN
 
 
 -- !query 9
@@ -79,7 +79,7 @@ SELECT float('infinity')
 -- !query 9 schema
 struct<CAST(infinity AS FLOAT):float>
 -- !query 9 output
-NULL
+Infinity
 
 
 -- !query 10
@@ -87,7 +87,7 @@ SELECT float('          -INFINiTY   ')
 -- !query 10 schema
 struct<CAST(          -INFINiTY    AS FLOAT):float>
 -- !query 10 output
-NULL
+-Infinity
 
 
 -- !query 11
@@ -135,7 +135,7 @@ SELECT float('nan') / float('nan')
 -- !query 16 schema
 struct<(CAST(CAST(nan AS FLOAT) AS DOUBLE) / CAST(CAST(nan AS FLOAT) AS DOUBLE)):double>
 -- !query 16 output
-NULL
+NaN
 
 
 -- !query 17

sql/core/src/test/resources/sql-tests/results/pgSQL/float8.sql.out

@@ -95,7 +95,7 @@ SELECT double('nan')
 -- !query 11 schema
 struct<CAST(nan AS DOUBLE):double>
 -- !query 11 output
-NULL
+NaN
 
 
 -- !query 12
@@ -103,7 +103,7 @@ SELECT double('   NAN  ')
 -- !query 12 schema
 struct<CAST(   NAN   AS DOUBLE):double>
 -- !query 12 output
-NULL
+NaN
 
 
 -- !query 13
@@ -111,7 +111,7 @@ SELECT double('infinity')
 -- !query 13 schema
 struct<CAST(infinity AS DOUBLE):double>
 -- !query 13 output
-NULL
+Infinity
 
 
 -- !query 14
@@ -119,7 +119,7 @@ SELECT double('          -INFINiTY   ')
 -- !query 14 schema
 struct<CAST(          -INFINiTY    AS DOUBLE):double>
 -- !query 14 output
-NULL
+-Infinity
 
 
 -- !query 15