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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
     */
    @Override
    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; } @Override public TemplateModel getTemplateModel() { return model; } @Override public PyObject __finditem__(PyObject key) { if (key instanceof PyInteger) { return __finditem__(((PyInteger) key).getValue()); } return __finditem__(key.toString()); } @Override 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() + ")"); } @Override 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() + ")"); } @Override 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 ? wrap(args[i]) : 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() + ")"); } @Override 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; } @Override 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(); } } }




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