/*
* FreeMarker: a tool that allows Java programs to generate HTML
* output using templates.
* Copyright (C) 1998-2004 Benjamin Geer
* Email: beroul@users.sourceforge.net
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
package freemarker.template.instruction;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.Writer;
import freemarker.template.TemplateException;
import freemarker.template.TemplateListModel;
import freemarker.template.TemplateListModel2;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateModelException;
import freemarker.template.TemplateProcessor;
import freemarker.template.TemplateRuntimeHandler;
import freemarker.template.TemplateScalarModel;
import freemarker.template.TemplateWriteableHashModel;
import freemarker.template.compiler.ParseException;
import freemarker.template.compiler.TemplateBuilder;
import freemarker.template.expression.Expression;
import freemarker.template.expression.ExpressionUtils;
import freemarker.template.expression.Identifier;
import freemarker.template.expression.Variable;
/**
* An instruction that processes a {@link freemarker.template.TemplateListModel}
* or {@link freemarker.template.TemplateListModel2}. This can be either in the
* form of a <code><list ... as ...></code> instruction or a
* <code><foreach ... in ...></code> instruction.
*
* @version $Id: ListInstruction.java 1123 2005-10-04 10:48:25Z run2000 $
*/
public final class ListInstruction extends GenericStartInstruction {
/**
* @serial the expression that evaluates to a template list model
*/
private final Expression listExpression;
/**
* @serial the variable used to index over the list
*/
private final Identifier indexVariable;
/** Serialization UUID for this class. */
private static final long serialVersionUID = -5366066980827389242L;
/**
* Constructs a list/foreach instruction containing the list variable and
* the index variable.
*
* @param listExpression
* a variable or list expression referring to a
* <code>TemplateListModel</code>.
* @param indexVariable
* an arbitrary index variable.
* @throws NullPointerException
* list expression or index variable are null
* @throws IllegalArgumentException
* the list expression wasn't a list
*/
public ListInstruction(Expression listExpression, Identifier indexVariable) {
if (indexVariable == null) {
throw new NullPointerException("Index variable in list instruction cannot be null");
}
if ((listExpression.getType() & ExpressionUtils.EXPRESSION_TYPE_LIST) == 0) {
throw new IllegalArgumentException("List instruction must contain a list");
}
this.listExpression = listExpression;
this.indexVariable = indexVariable;
}
/**
* Is this the right kind of instruction for the given
* {@link EndInstruction}?
*
* @param endInstruction
* the end instruction we're testing
* @return <code>true</code> if the <code>EndInstruction</code> is a list
* end instruction, otherwise <code>false</code>
*/
public boolean testEndInstruction(Instruction endInstruction) {
return (endInstruction.getEndType() == LIST_END);
}
/**
* Call the {@link freemarker.template.compiler.TemplateBuilder} with this
* list instruction.
*
* @param builder
* the <code>TemplateBuilder</code> to be called back
*/
public TemplateProcessor callBuilder(TemplateBuilder builder) throws ParseException {
return builder.buildStatement(this);
}
/**
* Processes the <code><list ... ></code> or
* <code><foreach ... ></code> instruction.
*
* @param modelRoot
* the root node of the data model.
* @param out
* a <code>Writer</code> to send the output to.
* @param eventHandler
* a <code>TemplateEventAdapter</code> for handling any events
* that occur during processing.
*/
public short process(TemplateWriteableHashModel modelRoot, Writer out, TemplateRuntimeHandler eventHandler) throws IOException {
if (body == null) {
return TemplateProcessor.OK;
}
String listVariableName;
try {
if (listExpression instanceof Variable) {
listVariableName = ((Variable) listExpression).getName(modelRoot);
} else {
listVariableName = "list literal";
}
} catch (TemplateException te) {
eventHandler.fireExceptionThrown(this, new TemplateException("Couldn't resolve name of list variable", te), out,
"freemarker.template.instruction.ListInstruction.process", TemplateRuntimeHandler.SEVERITY_WARNING);
return TemplateProcessor.OK;
}
TemplateModel baseModel;
try {
baseModel = listExpression.getAsTemplateModel(modelRoot);
} catch (TemplateException te) {
eventHandler.fireExceptionThrown(this, new TemplateException("Couldn't get referent of " + listVariableName, te), out,
"freemarker.template.instruction.ListInstruction.process", TemplateRuntimeHandler.SEVERITY_WARNING);
return TemplateProcessor.OK;
}
try {
if ((baseModel == null) || (baseModel.isEmpty())) {
return TemplateProcessor.OK;
}
} catch (TemplateModelException e) {
eventHandler.fireExceptionThrown(this, new TemplateException("Couldn't perform list instruction on " + listVariableName, e), out,
"freemarker.template.instruction.ListInstruction.process", TemplateRuntimeHandler.SEVERITY_WARNING);
return TemplateProcessor.OK;
}
ListArgumentWrapper wrapper = null;
String indexName = indexVariable.getName();
try {
if (baseModel instanceof TemplateListModel2) {
wrapper = new List2ArgumentWrapper(modelRoot, (TemplateListModel2) baseModel, indexName);
} else if (baseModel instanceof TemplateListModel) {
wrapper = new List1ArgumentWrapper(modelRoot, (TemplateListModel) baseModel, indexName);
} else if (baseModel instanceof TemplateScalarModel) {
wrapper = new ScalarArgumentWrapper(modelRoot, baseModel, indexName);
}
} catch (TemplateModelException e) {
eventHandler.fireExceptionThrown(this, new TemplateException("Couldn't initialize list " + listVariableName, e), out,
"freemarker.template.instruction.ListInstruction.process", TemplateRuntimeHandler.SEVERITY_WARNING);
}
try {
// Loop, setting the index to refer to each element in turn.
short result;
while (wrapper.next()) {
result = body.process(wrapper, out, eventHandler);
if (result == TemplateProcessor.BREAK) {
break;
} else if (result != TemplateProcessor.OK) {
return result;
}
}
} catch (TemplateModelException e) {
eventHandler.fireExceptionThrown(this, new TemplateException("Couldn't read from list " + listVariableName, e), out,
"freemarker.template.instruction.ListInstruction.process", TemplateRuntimeHandler.SEVERITY_WARNING);
} finally {
// Clear any local variables still initialized.
wrapper.reset();
}
return TemplateProcessor.OK;
}
/**
* Returns a string representation of the object.
*
* @return a <code>String</code> representing this instruction subtree
*/
public String toString() {
StringBuffer buffer = new StringBuffer();
buffer.append("list ");
buffer.append(listExpression);
buffer.append(" as ");
buffer.append(indexVariable);
buffer.append(' ');
buffer.append(body);
return buffer.toString();
}
/**
* When deserializing this object, read the object normally, test whether
* the list expression or index variable is null, then recreate the
* transient iterator field.
*
* @param stream
* the input stream to read serialized objects from
*/
private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
stream.defaultReadObject();
if ((listExpression == null) || (indexVariable == null)) {
throw new InvalidObjectException("Cannot create a ListInstruction with a null expression or index variable");
}
}
}