Package com.singularsys.jep.misc.functions

# Class Switch

java.lang.Object
com.singularsys.jep.functions.PostfixMathCommand
com.singularsys.jep.misc.functions.Switch

All Implemented Interfaces:
  `CallbackEvaluationI`, `PostfixMathCommandI`, `Serializable`

public class Switch extends PostfixMathCommand implements CallbackEvaluationI
A switch statement. The argument is selected based on the integer value of the first argument for example `switch(2,5,6,7,8)` will return 6. The first argument must be an exact integer.

This is the lazy evaluation version, it will only evaluate arguments when needed. Use `SwitchNonLazy` for a non-lazy version which evaluates all arguments before evaluation.

Author:
  Richard Morris
See Also:
  - `Case`
  - `SwitchDefault`
  - Serialized Form

- ## Nested Class Summary

  Nested Classes
  Modifier and Type
  Class
  Description
  `static enum`
  `Switch.NullBehaviour`
  Action to take if first argument is null.

- ## Field Summary

  ### Fields inherited from class com.singularsys.jep.functions.PostfixMathCommand

  `curNumberOfParameters, description, name, NaN, numberOfParameters`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `Switch()`
  Default switch statement.
  `Switch(Switch.NullBehaviour nullBehaviour)`
  Switch function with defined null behaviour.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `boolean`
  `checkNumberOfParameters(int n)`
  Must have at least 2 parameters.
  `Object`
  `evaluate(Node node, Evaluator pv)`
  Performs some special evaluation on the node.
  `Switch.NullBehaviour`
  `getNullBehaviour()`
  Behaviour when passed zero arguments.

  ### Methods inherited from class com.singularsys.jep.functions.PostfixMathCommand

  `asArray, asBool, asDouble, asInt, asLong, asStrictInt, asString, asType, getDescription, getDescription, getDescriptionWithType, getName, getNumberOfParameters, run, setCurNumberOfParameters, setDescription, setName, toString, toString`

  ### Methods inherited from class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- ## Constructor Details

  - ### Switch

    public Switch()
    Default switch statement. Exceptions are thrown if first argument is null.

  - ### Switch

    public Switch(Switch.NullBehaviour nullBehaviour)
    Switch function with defined null behaviour.
    Parameters:
      `nullBehaviour` - action to take if first argument is null.
    Since:
      Jep 3.5

- ## Method Details

  - ### getNullBehaviour

    public Switch.NullBehaviour getNullBehaviour()
    Behaviour when passed zero arguments.
    Returns:
      code indicating behaviour type
    Since:
      Jep 3.5

  - ### checkNumberOfParameters

    public boolean checkNumberOfParameters(int n)
    Must have at least 2 parameters.
    Specified by:
      `checkNumberOfParameters` in interface `PostfixMathCommandI`
    Overrides:
      `checkNumberOfParameters` in class `PostfixMathCommand`
    Parameters:
      `n` - number of parameters function will be called with.
    Returns:
      false if an illegal number of parameters is supplied, true otherwise.

  - ### evaluate

    public Object evaluate(Node node, Evaluator pv) throws EvaluationException
    Description copied from interface: `CallbackEvaluationI`
    Performs some special evaluation on the node. This method has the responsibility for evaluating the children of the node, and it should generally call

         pv.eval(node.jjtGetChild(i))

    for each child. The SymbolTable is not passed as an argument. This is because it is better practice to get and set variable values by using node.getVar().setValue() rather that through the SymbolTable with requires a hashtable lookup.
    Specified by:
      `evaluate` in interface `CallbackEvaluationI`
    Parameters:
      `node` - The current node
      `pv` - The visitor, can be used evaluate the children
    Returns:
      the value after evaluation. This value will be passed to other functions higher up the node tree. The value can be any type including Double or Vector<Object>
    Throws:
      `EvaluationException` - if the calculation cannot be performed
    See Also:
      - `Evaluator`