Package com.mckoi.database
Class AbstractFunction
- java.lang.Object
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- com.mckoi.database.AbstractFunction
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- All Implemented Interfaces:
Function
- Direct Known Subclasses:
AbstractAggregateFunction
public abstract class AbstractFunction extends java.lang.Object implements Function
An abstract implementation of Function.- Author:
- Tobias Downer
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Constructor Summary
Constructors Constructor Description AbstractFunction(java.lang.String name, Expression[] params)
Constructs the Function with the given expression array as parameters.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description java.util.List
allElements()
Returns the list of all elements that are used by this function.java.util.List
allVariables()
Returns the list of all Variable's that are used by this function.java.lang.String
getName()
Returns the name of the function.Expression
getParameter(int n)
Returns the parameter at the given index in the parameters list.void
init(VariableResolver resolver)
The init function.boolean
isAggregate(QueryContext context)
Returns whether the function is an aggregate function or not.boolean
isGlob()
Returns true if the param is the special case glob parameter (*).int
parameterCount()
Returns the number of parameters for this function.void
prepareParameters(ExpressionPreparer preparer)
Prepares the parameters of the function.TType
returnTType()
TType
returnTType(VariableResolver resolver, QueryContext context)
By Default, we assume a function returns a Numeric object.protected void
setAggregate(boolean status)
Call this from the constructor if the function is an aggregate.java.lang.String
toString()
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Constructor Detail
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AbstractFunction
public AbstractFunction(java.lang.String name, Expression[] params)
Constructs the Function with the given expression array as parameters.
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Method Detail
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setAggregate
protected void setAggregate(boolean status)
Call this from the constructor if the function is an aggregate.
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parameterCount
public int parameterCount()
Returns the number of parameters for this function.
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getParameter
public Expression getParameter(int n)
Returns the parameter at the given index in the parameters list.
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isGlob
public boolean isGlob()
Returns true if the param is the special case glob parameter (*).
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getName
public java.lang.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.
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allVariables
public java.util.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 interfaceFunction
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allElements
public java.util.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 interfaceFunction
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isAggregate
public final boolean isAggregate(QueryContext context)
Returns whether the function is an aggregate function or not.- Specified by:
isAggregate
in interfaceFunction
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prepareParameters
public void prepareParameters(ExpressionPreparer preparer) throws DatabaseException
Prepares the parameters of the function.- Specified by:
prepareParameters
in interfaceFunction
- Throws:
DatabaseException
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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.
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returnTType
public TType returnTType(VariableResolver resolver, QueryContext context)
By Default, we assume a function returns a Numeric object.- Specified by:
returnTType
in interfaceFunction
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returnTType
public TType returnTType()
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toString
public java.lang.String toString()
- Overrides:
toString
in classjava.lang.Object
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