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Google App Engine compliant variation of FreeMarker.
FreeMarker is a "template engine"; a generic tool to generate text output based on templates.
/*
* Copyright 2014 Attila Szegedi, Daniel Dekany, Jonathan Revusky
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package freemarker.ext.jython;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.List;
import org.python.core.Py;
import org.python.core.PyDictionary;
import org.python.core.PyFloat;
import org.python.core.PyInteger;
import org.python.core.PyLong;
import org.python.core.PyObject;
import org.python.core.PySequence;
import org.python.core.PyString;
import org.python.core.PyStringMap;
import freemarker.ext.util.ModelCache;
import freemarker.ext.util.WrapperTemplateModel;
import freemarker.template.AdapterTemplateModel;
import freemarker.template.ObjectWrapper;
import freemarker.template.TemplateBooleanModel;
import freemarker.template.TemplateHashModel;
import freemarker.template.TemplateHashModelEx;
import freemarker.template.TemplateMethodModel;
import freemarker.template.TemplateMethodModelEx;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateModelAdapter;
import freemarker.template.TemplateModelException;
import freemarker.template.TemplateNumberModel;
import freemarker.template.TemplateScalarModel;
import freemarker.template.TemplateSequenceModel;
import freemarker.template.utility.OptimizerUtil;
/**
* An object wrapper that wraps Jython objects into FreeMarker template models
* and vice versa.
*/
public class JythonWrapper implements ObjectWrapper
{
private static final Class PYOBJECT_CLASS = PyObject.class;
public static final JythonWrapper INSTANCE = new JythonWrapper();
private final ModelCache modelCache = new JythonModelCache(this);
private boolean attributesShadowItems = true;
public JythonWrapper()
{
}
/**
* Sets whether this wrapper caches model instances. Default is false.
* When set to true, calling {@link #wrap(Object)} multiple times for
* the same object will return the same model.
*/
public void setUseCache(boolean useCache)
{
modelCache.setUseCache(useCache);
}
/**
* Sets whether attributes shadow items in wrapped objects. When true
* (this is the default value), ${object.name} will first
* try to locate a python attribute with the specified name on the object
* using {@link PyObject#__findattr__(java.lang.String)}, and only if it
* doesn't find the attribute will it call
* {@link PyObject#__getitem__(org.python.core.PyObject)}.
* When set to false, the lookup order is reversed and items
* are looked up before attributes.
*/
public synchronized void setAttributesShadowItems(boolean attributesShadowItems)
{
this.attributesShadowItems = attributesShadowItems;
}
boolean isAttributesShadowItems()
{
return attributesShadowItems;
}
/**
* Wraps the passed Jython object into a FreeMarker template model. If
* the object is not a Jython object, it's first coerced into one using
* {@link Py#java2py(java.lang.Object)}. {@link PyDictionary} and {@link
* PyStringMap} are wrapped into a hash model, {@link PySequence}
* descendants are wrapped into a sequence model, {@link PyInteger}, {@link
* PyLong}, and {@link PyFloat} are wrapped into a number model. All objects
* are wrapped into a scalar model (using {@link Object#toString()} and a
* boolean model (using {@link PyObject#__nonzero__()}. For internal
* general-purpose {@link PyObject}s returned from a call to {@link
* #unwrap(TemplateModel)}, the template model that was passed to
* unwrap is returned.
*/
public TemplateModel wrap(Object obj)
{
if(obj == null) {
return null;
}
return modelCache.getInstance(obj);
}
/**
* Coerces a template model into a {@link PyObject}.
* @param model the model to coerce
* @return the coerced model.
*
* -
*
- {@link AdapterTemplateModel}s (i.e. {@link freemarker.ext.beans.BeanModel}) are marshalled
* using the standard Python marshaller {@link Py#java2py(Object)} on
* the result of
getWrappedObject(PyObject.class)s. The
* native JythonModel instances will just return the underlying PyObject.
* - All other models that are {@link TemplateScalarModel scalars} are
* marshalled as {@link PyString}.
*
- All other models that are {@link TemplateNumberModel numbers} are
* marshalled using the standard Python marshaller
* {@link Py#java2py(Object)} on their underlying
Number
* - All other models are marshalled to a generic internal
*
PyObject subclass that'll correctly pass
* __finditem__, __len__,
* __nonzero__, and __call__ invocations to
* appropriate hash, sequence, and method models.
*
*/
public PyObject unwrap(TemplateModel model) throws TemplateModelException
{
if(model instanceof AdapterTemplateModel) {
return Py.java2py(((AdapterTemplateModel)model).getAdaptedObject(
PYOBJECT_CLASS));
}
if(model instanceof WrapperTemplateModel) {
return Py.java2py(((WrapperTemplateModel)model).getWrappedObject());
}
// Scalars are marshalled to PyString.
if(model instanceof TemplateScalarModel)
{
return new PyString(((TemplateScalarModel)model).getAsString());
}
// Numbers are wrapped to Python built-in numeric types.
if(model instanceof TemplateNumberModel)
{
Number number = ((TemplateNumberModel)model).getAsNumber();
if(number instanceof BigDecimal)
{
number = OptimizerUtil.optimizeNumberRepresentation(number);
}
if(number instanceof BigInteger)
{
// Py.java2py can't automatically coerce a BigInteger into
// a PyLong. This will probably get fixed in later Jython
// release.
return new PyLong((BigInteger)number);
}
else
{
return Py.java2py(number);
}
}
// Return generic TemplateModel-to-Python adapter
return new TemplateModelToJythonAdapter(model);
}
private class TemplateModelToJythonAdapter extends PyObject
implements TemplateModelAdapter
{
private final TemplateModel model;
TemplateModelToJythonAdapter(TemplateModel model)
{
this.model = model;
}
public TemplateModel getTemplateModel()
{
return model;
}
public PyObject __finditem__(PyObject key)
{
if(key instanceof PyInteger)
{
return __finditem__(((PyInteger)key).getValue());
}
return __finditem__(key.toString());
}
public PyObject __finditem__(String key)
{
if(model instanceof TemplateHashModel)
{
try
{
return unwrap(((TemplateHashModel)model).get(key));
}
catch(TemplateModelException e)
{
throw Py.JavaError(e);
}
}
throw Py.TypeError("item lookup on non-hash model (" + getModelClass() + ")");
}
public PyObject __finditem__(int index)
{
if(model instanceof TemplateSequenceModel)
{
try
{
return unwrap(((TemplateSequenceModel)model).get(index));
}
catch(TemplateModelException e)
{
throw Py.JavaError(e);
}
}
throw Py.TypeError("item lookup on non-sequence model (" + getModelClass() + ")");
}
public PyObject __call__(PyObject args[], String keywords[])
{
if(model instanceof TemplateMethodModel)
{
boolean isEx = model instanceof TemplateMethodModelEx;
List list = new ArrayList(args.length);
try
{
for(int i = 0; i < args.length; ++i)
{
list.add(
isEx
? (Object)wrap(args[i])
: (Object)(
args[i] == null
? null
: args[i].toString()));
}
return unwrap((TemplateModel) ((TemplateMethodModelEx)model).exec(list));
}
catch(TemplateModelException e)
{
throw Py.JavaError(e);
}
}
throw Py.TypeError("call of non-method model (" + getModelClass() + ")");
}
public int __len__()
{
try
{
if(model instanceof TemplateSequenceModel)
{
return ((TemplateSequenceModel)model).size();
}
if(model instanceof TemplateHashModelEx)
{
return ((TemplateHashModelEx)model).size();
}
}
catch(TemplateModelException e)
{
throw Py.JavaError(e);
}
return 0;
}
public boolean __nonzero__()
{
try
{
if(model instanceof TemplateBooleanModel)
{
return ((TemplateBooleanModel)model).getAsBoolean();
}
if(model instanceof TemplateSequenceModel)
{
return ((TemplateSequenceModel)model).size() > 0;
}
if(model instanceof TemplateHashModel)
{
return !((TemplateHashModelEx)model).isEmpty();
}
}
catch(TemplateModelException e)
{
throw Py.JavaError(e);
}
return false;
}
private String getModelClass()
{
return model == null ? "null" : model.getClass().getName();
}
}
}