Package com.singularsys.jep.misc.functions

# Class Case

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

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

public class Case extends PostfixMathCommand implements CallbackEvaluationI
A case statement. The argument first argument is evaluated and then checked against the 2nd, 4th, 6th argument if the two are equal then the 3rd, 5th, 7th argument is returned. If no arguments match then the last argument is returned (if the number of args is even) for example `case("c","a",5,"b",6,"c",7,8)` will return 7.

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

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

- ## Nested Class Summary

  Nested Classes
  Modifier and Type
  Class
  Description
  `static enum`
  `Case.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
  `Case()`
  Standard constructor with no default value and errors if nulls are found.
  `Case(Case.NullBehaviour nullBehaviour)`
  Constructor with defined behaviour for null.
  `Case(Object defaultVal)`
  A case statement with a predefined default value and errors if nulls are found.
  `Case(Object defaultVal, Case.NullBehaviour nullBehaviour)`
  Case statement with given default value and defined null behaviour.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `boolean`
  `checkNumberOfParameters(int n)`
  Must have at least 3 parameters.
  `Object`
  `evaluate(Node node, Evaluator pv)`
  Performs some special evaluation on the node.
  `Object`
  `getDefaultVal()`
  The default value, only meaningful if isHasDefault() is true.
  `Case.NullBehaviour`
  `getNullBehaviour()`
  Behaviour when passed zero arguments.
  `boolean`
  `isHasDefault()`
  Whether a default value is set

  ### 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

  - ### Case

    public Case()
    Standard constructor with no default value and errors if nulls are found.

  - ### Case

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

  - ### Case

    public Case(Object defaultVal)
    A case statement with a predefined default value and errors if nulls are found.
    Parameters:
      `defaultVal` - The default value to return when no cases match
    Since:
      Jep 3.5

  - ### Case

    public Case(Object defaultVal, Case.NullBehaviour nullBehaviour)
    Case statement with given default value and defined null behaviour.
    Parameters:
      `defaultVal` - The default value to return when no cases match
      `nullBehaviour` - action to take if first argument is null
    Since:
      Jep 3.5

- ## Method Details

  - ### isHasDefault

    public boolean isHasDefault()
    Whether a default value is set
    Returns:
      true if a default value is set
    Since:
      Jep 3.5

  - ### getDefaultVal

    public Object getDefaultVal()
    The default value, only meaningful if isHasDefault() is true.
    Returns:
      the default value used.
    Since:
      Jep 3.5

  - ### getNullBehaviour

    public Case.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 3 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`