Package com.mckoi.database

Class AbstractFunction

java.lang.Object
com.mckoi.database.AbstractFunction
All Implemented Interfaces:
Function
Direct Known Subclasses:
AbstractAggregateFunction
public abstract class AbstractFunction extends Object implements Function
An abstract implementation of Function.
Author:
Tobias Downer

  • Constructor Details

    • AbstractFunction

      public AbstractFunction(String name, Expression[] params)
      Constructs the Function with the given expression array as parameters.

  • Method Details

    • setAggregate

      protected void setAggregate(boolean status)
      Call this from the constructor if the function is an aggregate.

    • parameterCount

      public int parameterCount()
      Returns the number of parameters for this function.

    • getParameter

      public Expression getParameter(int n)
      Returns the parameter at the given index in the parameters list.

    • isGlob

      public boolean isGlob()
      Returns true if the param is the special case glob parameter (*).

    • getName

      public String getName()
      Returns the name of the function. The name is a unique identifier that can be used to recreate this function. This identifier can be used to easily serialize the function when grouped with its parameters.
      Specified by:
      getName in interface Function

    • allVariables

      public List allVariables()
      Returns the list of all Variable's that are used by this function. This looks up each expression in the list of parameters. This will cascade if the expressions have a Function, etc.
      Specified by:
      allVariables in interface Function

    • allElements

      public List allElements()
      Returns the list of all elements that are used by this function. This looks up each expression in the list of parameters. This will cascade if the expressions have a Function, etc.
      Specified by:
      allElements in interface Function

    • isAggregate

      public final boolean isAggregate(QueryContext context)
      Returns whether the function is an aggregate function or not.
      Specified by:
      isAggregate in interface Function

    • prepareParameters

      public void prepareParameters(ExpressionPreparer preparer) throws DatabaseException
      Prepares the parameters of the function.
      Specified by:
      prepareParameters in interface Function
      Throws:
      DatabaseException

    • init

      public void init(VariableResolver resolver)
      The init function. By default, we don't do anything however this should be overwritten if we need to check the parameter arguments.

    • returnTType

      public TType returnTType(VariableResolver resolver, QueryContext context)
      By Default, we assume a function returns a Numeric object.
      Specified by:
      returnTType in interface Function

    • returnTType

      public TType returnTType()

    • toString

      public String toString()
      Overrides:
      toString in class Object