org.jfree.report.expressions
Interface Function
- All Superinterfaces:
- java.lang.Cloneable, Expression, java.io.Serializable
- All Known Implementing Classes:
- FormulaFunction
public interface Function
- extends Expression
The interface for report functions. A report function separates the business
logic from presentation of the result.
Since JFreeReport 0.9 functions are considered immutable. During the
advancement process, the function returns a new instance with the updated
state.
- Author:
- Thomas Morgner
Method Summary |
Function |
advance()
When the advance method is called, the function is asked to perform the
next step of its computation. |
Methods inherited from interface org.jfree.report.expressions.Expression |
clone, computeValue, getInstance, getName, isDeepTraversing, isPrecompute, isPreserve, setDeepTraversing, setName, setPrecompute, setPreserve, setRuntime |
advance
Function advance()
throws DataSourceException
- When the advance method is called, the function is asked to perform the
next step of its computation.
The original function must not be altered during that step (or more
correctly, calling advance on the original expression again must not return
a different result).
- Returns:
- a copy of the function containing the new state.
- Throws:
DataSourceException