feat: add Logarithm, Exponential and Sqrt functions

docs/developer-guide/syntax-reference.rst

@@ -59,7 +59,7 @@ supported KSQL types, including the complex types ``MAP``, ``ARRAY``, and
 ``STRUCT``.
 
 .. note::
-    
+
     ``Properties`` is not a valid field name.
 
 Here's an example CREATE STREAM statement that uses a ``STRUCT`` to
@@ -90,7 +90,7 @@ KSQL Time Units
 The following list shows valid time units for the SIZE, ADVANCE BY, SESSION, and
 WITHIN clauses.
 
-* DAY, DAYS 
+* DAY, DAYS
 * HOUR, HOURS
 * MINUTE, MINUTES
 * SECOND, SECONDS
@@ -108,13 +108,13 @@ timestamp in ``ROWTIME``. By default, the implicit ``ROWTIME`` column is the
 timestamp of a message in a Kafka topic. Timestamps have an accuracy of
 one millisecond.
 
-Use the TIMESTAMP property to override ``ROWTIME`` with the contents of the 
+Use the TIMESTAMP property to override ``ROWTIME`` with the contents of the
 specified column. Define the format of a record's timestamp by using the
 TIMESTAMP_FORMAT property.
 
 If you use the TIMESTAMP property but don't set TIMESTAMP_FORMAT, KSQL assumes
 that the timestamp field is a ``bigint``. If you set TIMESTAMP_FORMAT, the
-TIMESTAMP field must be of type ``varchar`` and have a format that the 
+TIMESTAMP field must be of type ``varchar`` and have a format that the
 ``DateTimeFormatter`` Java class can parse.
 
 If your timestamp format has embedded single quotes, you can escape them by
@@ -1559,6 +1559,8 @@ Scalar functions
 |                        |                                                                           |                                                   |
 |                        |                                                                           | ``{"foo": {"bar": "quux"}}``                      |
 +------------------------+---------------------------------------------------------------------------+---------------------------------------------------+
+| EXP                    |  ``EXP(col1)``                                                            | The exponential of a value.                       |
++------------------------+---------------------------------------------------------------------------+---------------------------------------------------+
 | FIELD                  | ``FIELD(str VARCHAR, args VARCHAR[])``                                    | Returns the 1-indexed position of ``str`` in      |
 |                        |                                                                           | ``args``, or 0 if not found. If ``str`` is NULL,  |
 |                        |                                                                           | the return value is 0, because NULL is not        |
@@ -1581,6 +1583,8 @@ Scalar functions
 +------------------------+---------------------------------------------------------------------------+---------------------------------------------------+
 | LEN                    |  ``LEN(col1)``                                                            | The length of a string.                           |
 +------------------------+---------------------------------------------------------------------------+---------------------------------------------------+
+| LN                     |  ``LN(col1)``                                                             | The natural logarithm of a value.                 |
++------------------------+---------------------------------------------------------------------------+---------------------------------------------------+
 | MASK                   |  ``MASK(col1, 'X', 'x', 'n', '-')``                                       | Convert a string to a masked or obfuscated        |
 |                        |                                                                           | version of itself. The optional arguments         |
 |                        |                                                                           | following the input string to be masked are the   |
@@ -1624,6 +1628,8 @@ Scalar functions
 +------------------------+---------------------------------------------------------------------------+---------------------------------------------------+
 | ROUND                  |  ``ROUND(col1)``                                                          | Round a value to the nearest BIGINT value.        |
 +------------------------+---------------------------------------------------------------------------+---------------------------------------------------+
+| SQRT                   |  ``SQRT(col1)``                                                           | The square root of a value.                       |
++------------------------+---------------------------------------------------------------------------+---------------------------------------------------+
 | SPLIT                  |  ``SPLIT(col1, delimiter)``                                               | Splits a string into an array of substrings based |
 |                        |                                                                           | on a delimiter. If the delimiter is not found,    |
 |                        |                                                                           | then the original string is returned as the only  |

ksql-common/src/main/java/io/confluent/ksql/util/KsqlConstants.java

@@ -20,6 +20,8 @@ public final class KsqlConstants {
   private KsqlConstants() {
   }
 
+  public static final String CONFLUENT_AUTHOR = "Confluent";
+
   public static final String KSQL_INTERNAL_TOPIC_PREFIX = "_confluent-ksql-";
   public static final String CONFLUENT_INTERNAL_TOPIC_PREFIX = "__confluent";
 

ksql-engine/src/main/java/io/confluent/ksql/function/udf/datetime/DateToString.java

@@ -22,11 +22,12 @@
 import io.confluent.ksql.function.udf.Udf;
 import io.confluent.ksql.function.udf.UdfDescription;
 import io.confluent.ksql.function.udf.UdfParameter;
+import io.confluent.ksql.util.KsqlConstants;
 import java.time.LocalDate;
 import java.time.format.DateTimeFormatter;
 import java.util.concurrent.ExecutionException;
 
-@UdfDescription(name = "datetostring", author = "Confluent",
+@UdfDescription(name = "datetostring", author = KsqlConstants.CONFLUENT_AUTHOR,
     description = "Converts an integer representing days since epoch to a date string"
         + " using the given format pattern. Note this is the format Kafka Connect uses"
         + " to represent dates with no time component.  The format pattern should be"

ksql-engine/src/main/java/io/confluent/ksql/function/udf/datetime/StringToDate.java

@@ -22,11 +22,12 @@
 import io.confluent.ksql.function.udf.Udf;
 import io.confluent.ksql.function.udf.UdfDescription;
 import io.confluent.ksql.function.udf.UdfParameter;
+import io.confluent.ksql.util.KsqlConstants;
 import java.time.LocalDate;
 import java.time.format.DateTimeFormatter;
 import java.util.concurrent.ExecutionException;
 
-@UdfDescription(name = "stringtodate", author = "Confluent",
+@UdfDescription(name = "stringtodate", author = KsqlConstants.CONFLUENT_AUTHOR,
     description = "Converts a string representation of a date into an integer representing"
         + " days since epoch using the given format pattern."
         + " Note this is the format Kafka Connect uses to represent dates with no time component."

ksql-engine/src/main/java/io/confluent/ksql/function/udf/datetime/StringToTimestamp.java

@@ -22,11 +22,12 @@
 import io.confluent.ksql.function.udf.Udf;
 import io.confluent.ksql.function.udf.UdfDescription;
 import io.confluent.ksql.function.udf.UdfParameter;
+import io.confluent.ksql.util.KsqlConstants;
 import io.confluent.ksql.util.timestamp.StringToTimestampParser;
 import java.time.ZoneId;
 import java.util.concurrent.ExecutionException;
 
-@UdfDescription(name = "stringtotimestamp", author = "Confluent",
+@UdfDescription(name = "stringtotimestamp", author = KsqlConstants.CONFLUENT_AUTHOR,
     description = "Converts a string representation of a date in the given format"
         + " into the BIGINT value that represents the millisecond timestamp.")
 public class StringToTimestamp {

ksql-engine/src/main/java/io/confluent/ksql/function/udf/datetime/TimestampToString.java

@@ -22,12 +22,13 @@
 import io.confluent.ksql.function.udf.Udf;
 import io.confluent.ksql.function.udf.UdfDescription;
 import io.confluent.ksql.function.udf.UdfParameter;
+import io.confluent.ksql.util.KsqlConstants;
 import java.sql.Timestamp;
 import java.time.ZoneId;
 import java.time.format.DateTimeFormatter;
 import java.util.concurrent.ExecutionException;
 
-@UdfDescription(name = "timestamptostring", author = "Confluent",
+@UdfDescription(name = "timestamptostring", author = KsqlConstants.CONFLUENT_AUTHOR,
     description = "Converts a BIGINT millisecond timestamp value into"
         + " the string representation of the timestamp in the given format.")
 public class TimestampToString {

ksql-engine/src/main/java/io/confluent/ksql/function/udf/geo/GeoDistance.java

@@ -20,7 +20,7 @@
 import io.confluent.ksql.function.udf.Udf;
 import io.confluent.ksql.function.udf.UdfDescription;
 import io.confluent.ksql.function.udf.UdfParameter;
-
+import io.confluent.ksql.util.KsqlConstants;
 import java.util.List;
 
 /**
@@ -31,7 +31,7 @@
  * <p>An optional fifth parameter allows to specify either "MI" (miles) or "KM" (kilometers) as the
  * desired unit for the output measurement. Default is KM.
  */
-@UdfDescription(name = "geo_distance", author = "Confluent",
+@UdfDescription(name = "geo_distance", author = KsqlConstants.CONFLUENT_AUTHOR,
     description = "Compute the distance between two points on the surface of the earth,"
         + " according to the Haversine formula for \"great circle distance\".")
 public class GeoDistance {

ksql-engine/src/main/java/io/confluent/ksql/function/udf/math/Exp.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2018 Confluent Inc.
+ *
+ * Licensed under the Confluent Community License; you may not use this file
+ * except in compliance with the License.  You may obtain a copy of the License at
+ *
+ * http://www.confluent.io/confluent-community-license
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OF ANY KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
+
+package io.confluent.ksql.function.udf.math;
+
+import io.confluent.ksql.function.udf.Udf;
+import io.confluent.ksql.function.udf.UdfDescription;
+import io.confluent.ksql.function.udf.UdfParameter;
+import io.confluent.ksql.util.KsqlConstants;
+
+@SuppressWarnings("WeakerAccess") // Invoked via reflection
+@UdfDescription(
+    name = "exp",
+    author = KsqlConstants.CONFLUENT_AUTHOR,
+    description = "The exponential of a value."
+)
+public class Exp {
+
+  @Udf(description = "Returns Euler's number e raised to the power of an INT value.")
+  public Double exp(
+      @UdfParameter(
+          value = "exponent",
+          description = "the exponent to raise e to."
+      ) final Integer exponent
+  ) {
+    return exp(exponent == null ? null : exponent.doubleValue());
+  }
+
+  @Udf(description = "Returns Euler's number e raised to the power of a BIGINT value.")
+  public Double exp(
+      @UdfParameter(
+          value = "exponent",
+          description = "the exponent to raise e to."
+      ) final Long exponent
+  ) {
+    return exp(exponent == null ? null : exponent.doubleValue());
+  }
+
+  @Udf(description = "Returns Euler's number e raised to the power of a DOUBLE value.")
+  public Double exp(
+      @UdfParameter(
+          value = "exponent",
+          description = "the exponent to raise e to."
+      ) final Double exponent
+  ) {
+    return exponent == null
+        ? null
+        : Math.exp(exponent);
+  }
+}

ksql-engine/src/main/java/io/confluent/ksql/function/udf/math/Ln.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2018 Confluent Inc.
+ *
+ * Licensed under the Confluent Community License; you may not use this file
+ * except in compliance with the License.  You may obtain a copy of the License at
+ *
+ * http://www.confluent.io/confluent-community-license
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OF ANY KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
+
+package io.confluent.ksql.function.udf.math;
+
+import io.confluent.ksql.function.udf.Udf;
+import io.confluent.ksql.function.udf.UdfDescription;
+import io.confluent.ksql.function.udf.UdfParameter;
+import io.confluent.ksql.util.KsqlConstants;
+
+@UdfDescription(
+    name = "ln",
+    author = KsqlConstants.CONFLUENT_AUTHOR,
+    description = "The natural logarithm of a value."
+)
+public class Ln {
+
+  @Udf(description = "Returns the natural logarithm (base e) of an INT value.")
+  public Double ln(
+        @UdfParameter(
+            value = "value",
+            description = "the value get the natual logarithm of."
+        ) final Integer value
+  ) {
+    return ln(value == null ? null : value.doubleValue());
+  }
+
+  @Udf(description = "Returns the natural logarithm (base e) of a BIGINT value.")
+  public Double ln(
+      @UdfParameter(
+          value = "value",
+          description = "the value get the natual logarithm of."
+      ) final Long value
+  ) {
+    return ln(value == null ? null : value.doubleValue());
+  }
+
+  @Udf(description = "Returns the natural logarithm (base e) of a DOUBLE value.")
+  public Double ln(
+      @UdfParameter(
+          value = "value",
+          description = "the value get the natual logarithm of."
+      ) final Double value
+  ) {
+    return value == null
+        ? null
+        : Math.log(value);
+  }
+}

ksql-engine/src/main/java/io/confluent/ksql/function/udf/math/Sqrt.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2018 Confluent Inc.
+ *
+ * Licensed under the Confluent Community License; you may not use this file
+ * except in compliance with the License.  You may obtain a copy of the License at
+ *
+ * http://www.confluent.io/confluent-community-license
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OF ANY KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
+
+package io.confluent.ksql.function.udf.math;
+
+import io.confluent.ksql.function.udf.Udf;
+import io.confluent.ksql.function.udf.UdfDescription;
+import io.confluent.ksql.function.udf.UdfParameter;
+import io.confluent.ksql.util.KsqlConstants;
+
+@SuppressWarnings("WeakerAccess") // Invoked via reflection
+@UdfDescription(
+    name = "sqrt",
+    author = KsqlConstants.CONFLUENT_AUTHOR,
+    description = "The square root of a value."
+)
+public class Sqrt {
+
+  @Udf(description = "Returns the correctly rounded positive square root of a DOUBLE value")
+  public Double sqrt(
+      @UdfParameter(
+          value = "value",
+          description = "The value to get the square root of."
+      ) final Integer value
+  ) {
+    return sqrt(value == null ? null : value.doubleValue());
+  }
+
+  @Udf(description = "Returns the correctly rounded positive square root of a DOUBLE value")
+  public Double sqrt(
+      @UdfParameter(
+          value = "value",
+          description = "The value to get the square root of."
+      ) final Long value
+  ) {
+    return sqrt(value == null ? null : value.doubleValue());
+  }
+
+  @Udf(description = "Returns the correctly rounded positive square root of a DOUBLE value")
+  public Double sqrt(
+      @UdfParameter(
+          value = "value",
+          description = "The value to get the square root of."
+      ) final Double value
+  ) {
+    return value == null
+        ? null
+        : Math.sqrt(value);
+  }
+}

ksql-engine/src/main/java/io/confluent/ksql/function/udf/string/MaskKeepLeftKudf.java

@@ -17,8 +17,9 @@
 
 import io.confluent.ksql.function.udf.Udf;
 import io.confluent.ksql.function.udf.UdfDescription;
+import io.confluent.ksql.util.KsqlConstants;
 
-@UdfDescription(name = MaskKeepLeftKudf.NAME, author = "Confluent",
+@UdfDescription(name = MaskKeepLeftKudf.NAME, author = KsqlConstants.CONFLUENT_AUTHOR,
     description = "Returns a version of the input string with all but the"
         + " specified number of left-most characters masked out."
         + " Default masking rules will replace all upper-case characters with 'X', all lower-case"

ksql-engine/src/main/java/io/confluent/ksql/function/udf/string/MaskKeepRightKudf.java

@@ -17,8 +17,9 @@
 
 import io.confluent.ksql.function.udf.Udf;
 import io.confluent.ksql.function.udf.UdfDescription;
+import io.confluent.ksql.util.KsqlConstants;
 
-@UdfDescription(name = MaskKeepRightKudf.NAME, author = "Confluent",
+@UdfDescription(name = MaskKeepRightKudf.NAME, author = KsqlConstants.CONFLUENT_AUTHOR,
     description = "Returns a version of the input string with all but the"
         + " specified number of right-most characters masked out."
         + " Default masking rules will replace all upper-case characters with 'X', all lower-case"

ksql-engine/src/main/java/io/confluent/ksql/function/udf/string/MaskKudf.java

@@ -17,8 +17,9 @@
 
 import io.confluent.ksql.function.udf.Udf;
 import io.confluent.ksql.function.udf.UdfDescription;
+import io.confluent.ksql.util.KsqlConstants;
 
-@UdfDescription(name = "mask", author = "Confluent",
+@UdfDescription(name = "mask", author = KsqlConstants.CONFLUENT_AUTHOR,
     description = "Returns a version of the input string with every character replaced by a mask."
         + " Default masking rules will replace all upper-case characters with 'X', all lower-case"
         + " characters with 'x', all digits with 'n', and any other character with '-'.")

ksql-engine/src/main/java/io/confluent/ksql/function/udf/string/MaskLeftKudf.java

@@ -17,8 +17,9 @@
 
 import io.confluent.ksql.function.udf.Udf;
 import io.confluent.ksql.function.udf.UdfDescription;
+import io.confluent.ksql.util.KsqlConstants;
 
-@UdfDescription(name = MaskLeftKudf.NAME, author = "Confluent",
+@UdfDescription(name = MaskLeftKudf.NAME, author = KsqlConstants.CONFLUENT_AUTHOR,
     description = "Returns a version of the input string with the"
         + " specified number of characters, starting from the beginning of the string, masked out."
         + " Default masking rules will replace all upper-case characters with 'X', all lower-case"

ksql-engine/src/main/java/io/confluent/ksql/function/udf/string/MaskRightKudf.java

@@ -17,8 +17,9 @@
 
 import io.confluent.ksql.function.udf.Udf;
 import io.confluent.ksql.function.udf.UdfDescription;
+import io.confluent.ksql.util.KsqlConstants;
 
-@UdfDescription(name = MaskRightKudf.NAME, author = "Confluent",
+@UdfDescription(name = MaskRightKudf.NAME, author = KsqlConstants.CONFLUENT_AUTHOR,
     description = "Returns a version of the input string with the"
         + " specified number of characters, counting back from the end of the string, masked out."
         + " Default masking rules will replace all upper-case characters with 'X', all lower-case"

ksql-engine/src/main/java/io/confluent/ksql/function/udf/string/SplitKudf.java

@@ -20,11 +20,12 @@
 import io.confluent.ksql.function.udf.Udf;
 import io.confluent.ksql.function.udf.UdfDescription;
 import io.confluent.ksql.function.udf.UdfParameter;
+import io.confluent.ksql.util.KsqlConstants;
 import java.util.Arrays;
 import java.util.List;
 import java.util.regex.Pattern;
 
-@UdfDescription(name = SplitKudf.NAME, author = "Confluent",
+@UdfDescription(name = SplitKudf.NAME, author = KsqlConstants.CONFLUENT_AUTHOR,
     description = "Splits a string into an array of substrings based on a delimiter. "
         + "If the delimiter is found at the beginning of the string, end of the string, or there "
         + "are contiguous delimiters in the string, then empty strings are added to the array. "