FunctionRegistry (Pinot Common JDK 8 0.11.0 API)

java.lang.Object
- org.apache.pinot.common.function.FunctionRegistry

```
public class FunctionRegistry
extends Object
```
Registry for scalar functions.
TODO: Merge FunctionRegistry and FunctionDefinitionRegistry to provide one single registry for all functions.

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method	Description
`static boolean`	`containsFunction(String functionName)`	Returns `true` if the given function name is registered, `false` otherwise.
`static FunctionInfo`	`getFunctionInfo(String functionName, int numParameters)`	Returns the `FunctionInfo` associated with the given function name and number of parameters, or `null` if there is no matching method.
`static void`	`init()`	Initializes the FunctionRegistry.
`static void`	`registerFunction(Method method, boolean nullableParameters)`	Registers a method with the name of the method.
`static void`	`registerFunction(String functionName, Method method, boolean nullableParameters)`	Registers a method with the given function name.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - init
```
public static void init()
```
    Initializes the FunctionRegistry. NOTE: This method itself is a NO-OP, but can be used to explicitly trigger the static block of registering the scalar functions via reflection.
  - registerFunction
```
public static void registerFunction(Method method,
                                    boolean nullableParameters)
```
    Registers a method with the name of the method.
  - registerFunction
```
public static void registerFunction(String functionName,
                                    Method method,
                                    boolean nullableParameters)
```
    Registers a method with the given function name.
  - containsFunction
```
public static boolean containsFunction(String functionName)
```
    Returns true if the given function name is registered, false otherwise.
  - getFunctionInfo
```
@Nullable
public static FunctionInfo getFunctionInfo(String functionName,
                                           int numParameters)
```
    Returns the FunctionInfo associated with the given function name and number of parameters, or null if there is no matching method. This method should be called after the FunctionRegistry is initialized and all methods are already registered.