org.apache.taglibs.standard.lang.jstl.FunctionInvocation Maven / Gradle / Ivy
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package org.apache.taglibs.standard.lang.jstl;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
/**
*
* Represents a function call.
*
* @author Shawn Bayern (in the style of Nathan's other classes)
**/
public class FunctionInvocation
extends Expression
{
//-------------------------------------
// Properties
//-------------------------------------
// property index
private String functionName;
private List argumentList;
public String getFunctionName() { return functionName; }
public void setFunctionName(String f) { functionName = f; }
public List getArgumentList() { return argumentList; }
public void setArgumentList(List l) { argumentList = l; }
//-------------------------------------
/**
* Constructor
**/
public FunctionInvocation (String functionName, List argumentList)
{
this.functionName = functionName;
this.argumentList = argumentList;
}
//-------------------------------------
// Expression methods
//-------------------------------------
/**
* Returns the expression in the expression language syntax
**/
public String getExpressionString ()
{
StringBuffer b = new StringBuffer();
b.append(functionName);
b.append("(");
Iterator i = argumentList.iterator();
while (i.hasNext()) {
b.append(((Expression) i.next()).getExpressionString());
if (i.hasNext())
b.append(", ");
}
b.append(")");
return b.toString();
}
//-------------------------------------
/**
*
* Evaluates by looking up the name in the VariableResolver
**/
public Object evaluate (Object pContext,
VariableResolver pResolver,
Map functions,
String defaultPrefix,
Logger pLogger)
throws ELException
{
// if the Map is null, then the function is invalid
if (functions == null)
pLogger.logError(Constants.UNKNOWN_FUNCTION, functionName);
// normalize function name against default prefix
String functionName = this.functionName;
if (functionName.indexOf(":") == -1) {
if (defaultPrefix == null)
pLogger.logError(Constants.UNKNOWN_FUNCTION, functionName);
functionName = defaultPrefix + ":" + functionName;
}
// ensure that the function's name is mapped
Method target = (Method) functions.get(functionName);
if (target == null)
pLogger.logError(Constants.UNKNOWN_FUNCTION, functionName);
// ensure that the number of arguments matches the number of parameters
Class[] params = target.getParameterTypes();
if (params.length != argumentList.size())
pLogger.logError(Constants.INAPPROPRIATE_FUNCTION_ARG_COUNT,
Integer.valueOf(params.length),
Integer.valueOf(argumentList.size()));
// now, walk through each parameter, evaluating and casting its argument
Object[] arguments = new Object[argumentList.size()];
for (int i = 0; i < params.length; i++) {
// evaluate
arguments[i] = ((Expression) argumentList.get(i)).evaluate(pContext,
pResolver,
functions,
defaultPrefix,
pLogger);
// coerce
arguments[i] = Coercions.coerce(arguments[i], params[i], pLogger);
}
// finally, invoke the target method, which we know to be static
try {
return (target.invoke(null, arguments));
} catch (InvocationTargetException ex) {
pLogger.logError(Constants.FUNCTION_INVOCATION_ERROR,
ex.getTargetException(),
functionName);
return null;
} catch (Exception ex) {
pLogger.logError(Constants.FUNCTION_INVOCATION_ERROR, ex, functionName);
return null;
}
}
//-------------------------------------
}