/*
* Copyright (C) 2012 Facebook, Inc.
*
* 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 com.facebook.swift.generator.util;
import com.google.common.base.Charsets;
import com.google.common.base.Function;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Iterables;
import com.google.common.io.InputSupplier;
import com.google.common.io.Resources;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.stringtemplate.v4.AttributeRenderer;
import org.stringtemplate.v4.ST;
import org.stringtemplate.v4.STErrorListener;
import org.stringtemplate.v4.STGroup;
import org.stringtemplate.v4.misc.ErrorManager;
import org.stringtemplate.v4.misc.STMessage;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.Map;
import javax.annotation.Nonnull;
public class TemplateLoader
{
private static final Function<String,InputSupplier<InputStreamReader>> FILE_TO_INPUT_SUPPLIER_TRANSFORM =
new Function<String, InputSupplier<InputStreamReader>>()
{
@Nonnull
@Override
public InputSupplier<InputStreamReader> apply(@Nonnull String templateFileName)
{
return Resources.newReaderSupplier(Resources.getResource(this.getClass(), "/templates/" + templateFileName), Charsets.UTF_8);
}
};
private static final Logger LOG = LoggerFactory.getLogger(TemplateLoader.class);
private final STErrorListener ERROR_LISTENER = new LoaderErrorListener();
private final Iterable<String> templateFileNames;
private volatile STGroup stg = null;
private Map<Class<?>, ? extends AttributeRenderer> attributeRenderers = ImmutableMap.of();
public TemplateLoader(final Iterable<String> templateFileNames)
{
this.templateFileNames = templateFileNames;
}
public TemplateLoader(final Iterable<String> templateFileNames,
final Map<Class<?>, ? extends AttributeRenderer> attributeRenderers)
{
this(templateFileNames);
this.attributeRenderers = attributeRenderers;
}
public ST load(final String templateName) throws IOException
{
final STGroup stg = getTemplateGroup(templateFileNames);
return stg.getInstanceOf(templateName);
}
protected STGroup getTemplateGroup(Iterable<String> templateFileNames) throws IOException
{
if (stg == null) {
// Convert set of relative paths to .st files into a set of input suppliers
Iterable<InputSupplier<InputStreamReader>> templateInputSuppliers =
Iterables.transform(templateFileNames, FILE_TO_INPUT_SUPPLIER_TRANSFORM);
// Combine the header and all .st files and load everything into a StringTemplateGroup
stg = new STGroup();
for (String templateFileName : templateFileNames) {
stg.importTemplates(getTemplateGroupFromFile(templateFileName));
}
for (Map.Entry<Class<?>, ? extends AttributeRenderer> entry : attributeRenderers.entrySet()) {
Class<?> cls = entry.getKey();
AttributeRenderer renderer = entry.getValue();
stg.registerRenderer(cls, renderer);
}
}
return stg;
}
protected STGroup getTemplateGroupFromFile(String fileName) throws IOException
{
final URL resourceUrl = Resources.getResource(this.getClass(), "/templates/" + fileName);
STGroup stg = new STGroup();
stg.errMgr = new ErrorManager(ERROR_LISTENER);
stg.loadGroupFile("", resourceUrl.toExternalForm());
return stg;
}
private static class LoaderErrorListener implements STErrorListener
{
@Override
public void compileTimeError(STMessage msg)
{
LOG.error(msg.toString());
}
@Override
public void runTimeError(STMessage msg)
{
LOG.error(msg.toString());
}
@Override
public void IOError(STMessage msg)
{
LOG.error(msg.toString());
}
@Override
public void internalError(STMessage msg)
{
LOG.error(msg.toString());
}
}
}