org.moremotion.evaluator
Interface MScriptFunction

All Known Implementing Classes:

MyFunc

public interface MScriptFunction

Defines an Interface for custom MScript Functions.

Custom MScript functions can be developed my implementing this interface.

When MScriptResolver encounters a function, i.e. @repeat() which is not built in, it first checks whether a function definition exist in the configuration files. For Example:

  <mscriptFunction name="repeat">
    <class>mypack.RepeaterMScriptFunction</class>
    <repeat-seperator>,</repeat-seperator>
  </mscriptFunction>
 

If it does, it loads the defined the class mypack.RepeaterMScriptFunction. If it does not then it assumes that the function name is a class name and tries to load it. It there is a success the resolver calls the execute(Expression[] params, MScriptFunctionContext msfc) method of the loaded class.

An Example Implementation

 package mypack;

 import org.moremotion.evaluator.*;
 import org.moremotion.servlet.*;
   
 public class RepeaterMScriptFunction implements MScriptFunction {
    
   public Object execute(Expression[] params, MScriptFunctionContext msfc) throws MScriptFunctionException {
     if (params.length < 2) throw new Exception("Less parameters than expected");
     MMSymbolResolver sr = msfc.getSymbolResolver();
     String seperator = msfc.getMScriptFunctionConfig().getParameter("repeat-seperator").stringValue(null);
     String s = params[0].evaluate(sr).toString(); 
     int times = ((Double)params[1].evaluate(sr)).intValue();
     StringBuffer result = new StringBuffer();
     for (int i = 0; i < times; i++) {
       if (result.length() > 0) result.append(seperator);
       result.append(s);
     } 
     return result.toString();
   } 
 }

 

Version:

$Id: MScriptFunction.java 476 2009-11-07 12:47:05Z erkan $

Field Summary

static java.lang.String

NULL_FUNCTION_RESULT

Method Summary

java.lang.Object

execute(Expression[] params, MScriptFunctionContext msfc) Executes the algorithm of the custom MScript function and returns the result.

Field Detail

NULL_FUNCTION_RESULT

static final java.lang.String NULL_FUNCTION_RESULT

See Also:

Constant Field Values

Method Detail

execute

java.lang.Object execute(Expression[] params,
                         MScriptFunctionContext msfc)
                         throws MScriptFunctionException

Executes the algorithm of the custom MScript function and returns the result.

Parameters:

params - The function parameters as Expression object array.

msfc - MScriptFunctionContext object

Returns:

The result object. The expected objects are String, Double and Boolean.

Throws:

MScriptFunctionException - when something goes wrong with the execution of the function.