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Groovy: A powerful, dynamic language for the JVM
/*
* 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 groovy.text.markup;
import groovy.lang.Closure;
import groovy.lang.Writable;
import groovy.text.Template;
import org.codehaus.groovy.control.io.NullWriter;
import org.codehaus.groovy.runtime.ExceptionUtils;
import org.codehaus.groovy.runtime.ResourceGroovyMethods;
import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import java.io.Writer;
import java.net.URL;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
import static groovy.xml.XmlUtil.escapeXml;
/**
* All templates compiled through {@link groovy.text.markup.MarkupTemplateEngine} extend this abstract class,
* which provides a number of utility methods to generate markup. An instance of this class can be obtained
* after calling {@link groovy.text.Template#make()} or {@link groovy.text.Template#make(java.util.Map)})} on
* a template generated by {@link groovy.text.markup.MarkupTemplateEngine#createTemplate(java.io.Reader)}.
*
* It is advised to use a distinct template instance for each thread (or more simply, each rendered document)
* for thread safety and avoiding mixing models.
*
* For the application needs, it is possible to provide more helper methods by extending this class and
* configuring the base template class using the {@link groovy.text.markup.TemplateConfiguration#setBaseTemplateClass(Class)}
* method.
*
* @author Cedric Champeau
*/
public abstract class BaseTemplate implements Writable {
private static final Map EMPTY_MODEL = Collections.emptyMap();
private final Map model;
private final Map modelTypes;
private final MarkupTemplateEngine engine;
private final TemplateConfiguration configuration;
private final Map cachedFragments;
private Writer out;
private boolean doWriteIndent;
public BaseTemplate(final MarkupTemplateEngine templateEngine, final Map model, final Map modelTypes, final TemplateConfiguration configuration) {
this.model = model==null?EMPTY_MODEL:model;
this.engine = templateEngine;
this.configuration = configuration;
this.modelTypes = modelTypes;
this.cachedFragments = new LinkedHashMap();
}
public Map getModel() {
return model;
}
public abstract Object run();
/**
* Renders the object provided as parameter using its {@link Object#toString()} method,
* The contents is rendered as is, unescaped. This means that depending on what the
* {@link Object#toString()} method call returns, you might create invalid markup.
* @param obj the object to be rendered unescaped
* @return this template instance
* @throws IOException
*/
public BaseTemplate yieldUnescaped(Object obj) throws IOException {
writeIndent();
out.write(obj.toString());
return this;
}
/**
* Renders the object provided as parameter using its {@link Object#toString()} method,
* The contents is rendered after being escaped for XML, enforcing valid XML output.
* @param obj the object to be rendered
* @return this template instance
* @throws IOException
*/
public BaseTemplate yield(Object obj) throws IOException {
writeIndent();
out.write(escapeXml(obj.toString()));
return this;
}
public String stringOf(Closure cl) throws IOException {
Writer old = out;
StringWriter stringWriter = new StringWriter(32);
out = stringWriter;
Object result = cl.call();
if (result!=null && result!=this) {
stringWriter.append(result.toString());
}
out = old;
return stringWriter.toString();
}
/**
* Renders the supplied object using its {@link Object#toString} method inside a
* comment markup block (<!-- ... -->). The object is rendered as is, unescaped.
* @param cs the object to be rendered inside an XML comment block.
* @return this template instance.
* @throws IOException
*/
public BaseTemplate comment(Object cs) throws IOException {
writeIndent();
out.write("");
return this;
}
/**
* Renders an XML declaration header. If the declaration encoding is set in the
* {@link TemplateConfiguration#getDeclarationEncoding() template configuration},
* then the encoding is rendered into the declaration.
* @return this template instance
* @throws IOException
*/
public BaseTemplate xmlDeclaration() throws IOException {
out.write("");
out.write(configuration.getNewLineString());
return this;
}
/**
* Renders processing instructions. The supplied map contains all elements to be
* rendered as processing instructions. The key is the name of the element, the value
* is either a map of attributes, or an object to be rendered directly. For example:
*
* pi("xml-stylesheet":[href:"mystyle.css", type:"text/css"])
*
*
* will be rendered as:
*
*
* <?xml-stylesheet href='mystyle.css' type='text/css'?>
*
*
* @param attrs the attributes to render
* @return this template instance
* @throws IOException
*/
public BaseTemplate pi(Map attrs) throws IOException {
for (Map.Entry entry : attrs.entrySet()) {
Object target = entry.getKey();
Object instruction = entry.getValue();
out.write("");
out.write(configuration.getNewLineString());
}
return this;
}
private void writeAttribute(String attName, String value) throws IOException {
out.write(attName);
out.write("=");
writeQt();
out.write(escapeQuotes(value));
writeQt();
}
private void writeQt() throws IOException {
if (configuration.isUseDoubleQuotes()) {
out.write('"');
} else {
out.write('\'');
}
}
private void writeIndent() throws IOException {
if (out instanceof DelegatingIndentWriter && doWriteIndent) {
((DelegatingIndentWriter)out).writeIndent();
doWriteIndent = false;
}
}
private String escapeQuotes(String str) {
String quote = configuration.isUseDoubleQuotes() ? "\"" : "'";
String escape = configuration.isUseDoubleQuotes() ? ""e;" : "'";
return str.replace(quote, escape);
}
/**
* This is the main method responsible for writing a tag and its attributes.
* The arguments may be:
*
* - a closure
in which case the closure is rendered inside the tag body
* - a string
, in which case the string is rendered as the tag body
* - a map of attributes
in which case the attributes are rendered inside the opening tag
*
* or a combination of (attributes,string), (attributes,closure)
* @param tagName the name of the tag
* @param args tag generation arguments
* @return this template instance
* @throws IOException
*/
public Object methodMissing(String tagName, Object args) throws IOException {
Object o = model.get(tagName);
if (o instanceof Closure) {
if (args instanceof Object[]) {
yieldUnescaped(((Closure) o).call((Object[])args));
return this;
}
yieldUnescaped(((Closure) o).call(args));
return this;
} else if (args instanceof Object[]) {
final Writer wrt = out;
TagData tagData = new TagData(args).invoke();
Object body = tagData.getBody();
writeIndent();
wrt.write('<');
wrt.write(tagName);
writeAttributes(tagData.getAttributes());
if (body != null) {
wrt.write('>');
writeBody(body);
writeIndent();
wrt.write("');
} else {
if (configuration.isExpandEmptyElements()) {
wrt.write(">');
} else {
wrt.write("/>");
}
}
}
return this;
}
private void writeBody(final Object body) throws IOException {
boolean indent = out instanceof DelegatingIndentWriter;
if (body instanceof Closure) {
if (indent) {
((DelegatingIndentWriter)(out)).next();
}
((Closure) body).call();
if (indent) {
((DelegatingIndentWriter)(out)).previous();
}
} else {
out.write(body.toString());
}
}
private void writeAttributes(final Map attributes) throws IOException {
if (attributes == null) {
return;
}
final Writer wrt = out;
for (Map.Entry entry : attributes.entrySet()) {
wrt.write(' ');
String attName = entry.getKey().toString();
String value = entry.getValue() == null ? "" : entry.getValue().toString();
writeAttribute(attName, value);
}
}
/**
* Includes another template inside this template.
* @param templatePath the path to the included resource.
* @throws IOException
* @throws ClassNotFoundException
*/
public void includeGroovy(String templatePath) throws IOException, ClassNotFoundException {
URL resource = engine.resolveTemplate(templatePath);
engine.createTypeCheckedModelTemplate(resource, modelTypes).make(model).writeTo(out);
}
/**
* Includes contents of another file, not as a template but as escaped text.
*
* @param templatePath the path to the other file
* @throws IOException
*/
public void includeEscaped(String templatePath) throws IOException {
URL resource = engine.resolveTemplate(templatePath);
yield(ResourceGroovyMethods.getText(resource, engine.getCompilerConfiguration().getSourceEncoding()));
}
/**
* Includes contents of another file, not as a template but as unescaped text.
*
* @param templatePath the path to the other file
* @throws IOException
*/
public void includeUnescaped(String templatePath) throws IOException {
URL resource = engine.resolveTemplate(templatePath);
yieldUnescaped(ResourceGroovyMethods.getText(resource, engine.getCompilerConfiguration().getSourceEncoding()));
}
/**
* Escapes the string representation of the supplied object if it derives from {@link java.lang.CharSequence},
* otherwise returns the object itself.
* @param contents an object to be escaped for XML
* @return an escaped string, or the object itself
*/
public Object tryEscape(Object contents) {
if (contents instanceof CharSequence) {
return escapeXml(contents.toString());
}
return contents;
}
/**
* Convenience method to return the current writer instance.
*
* @return the current writer
*/
public Writer getOut() {
return out;
}
/**
* Adds a new line to the output. The new line string can be configured by
* {@link groovy.text.markup.TemplateConfiguration#setNewLineString(String)}
* @throws IOException
*/
public void newLine() throws IOException {
yieldUnescaped(configuration.getNewLineString());
doWriteIndent = true;
}
/**
* Renders an embedded template as a fragment. Fragments are cached in a template, meaning that
* if you use the same fragment in a template, it will only be compiled once, but once per template
* instance. This is less performant than using {@link #layout(java.util.Map, String)}.
*
* @param model model to be passed to the template
* @param templateText template body
* @return this template instance
* @throws IOException
* @throws ClassNotFoundException
*/
public Object fragment(Map model, String templateText) throws IOException, ClassNotFoundException {
Template template = cachedFragments.get(templateText);
if (template==null) {
template = engine.createTemplate(new StringReader(templateText));
cachedFragments.put(templateText, template);
}
template.make(model).writeTo(out);
return this;
}
/**
* Imports a template and renders it using the specified model, allowing fine grained composition
* of templates and layouting. This works similarily to a template include but allows a distinct
* model to be used. This version doesn't inherit the model from the parent. If you need model
* inheritance, see {@link #layout(java.util.Map, String, boolean)}.
* @param model model to be passed to the template
* @param templateName the name of the template to be used as a layout
* @return this template instance
* @throws IOException
* @throws ClassNotFoundException
*/
public Object layout(Map model, String templateName) throws IOException, ClassNotFoundException {
return layout(model, templateName, false);
}
/**
* Imports a template and renders it using the specified model, allowing fine grained composition of templates and
* layouting. This works similarily to a template include but allows a distinct model to be used. If the layout
* inherits from the parent model, a new model is created, with the values from the parent model, eventually
* overridden with those provided specifically for this layout.
*
* @param model model to be passed to the template
* @param templateName the name of the template to be used as a layout
* @param inheritModel a boolean indicating if we should inherit the parent model
* @return this template instance
* @throws IOException
* @throws ClassNotFoundException
*/
public Object layout(Map model, String templateName, boolean inheritModel) throws IOException, ClassNotFoundException {
Map submodel = inheritModel ? forkModel(model) : model;
URL resource = engine.resolveTemplate(templateName);
engine.createTypeCheckedModelTemplate(resource, modelTypes).make(submodel).writeTo(out);
return this;
}
@SuppressWarnings("unchecked")
private Map forkModel(Map m) {
Map result = new HashMap();
result.putAll(model);
result.putAll(m);
return result;
}
/**
* Wraps a closure so that it can be used as a prototype for inclusion in layouts. This is useful when
* you want to use a closure in a model, but that you don't want to render the result of the closure but instead
* call it as if it was a specification of a template fragment.
* @param cl the fragment to be wrapped
* @return a wrapped closure returning an empty string
*/
public Closure contents(final Closure cl) {
return new Closure(cl.getOwner(), cl.getThisObject()) {
@Override
public Object call() {
cl.call();
return "";
}
@Override
public Object call(final Object... args) {
cl.call(args);
return "";
}
@Override
public Object call(final Object arguments) {
cl.call(arguments);
return "";
}
};
}
/**
* Main method used to render a template.
* @param out the Writer to which this Writable should output its data.
* @return a writer instance
* @throws IOException
*/
public Writer writeTo(final Writer out) throws IOException {
if (this.out!=null) {
// StackOverflow prevention
return NullWriter.DEFAULT;
}
try {
this.out = createWriter(out);
run();
return out;
} finally {
if (this.out!=null) {
this.out.flush();
}
this.out = null;
}
}
private Writer createWriter(final Writer out) {
return configuration.isAutoIndent() && !(out instanceof DelegatingIndentWriter)?new DelegatingIndentWriter(out, configuration.getAutoIndentString()):out;
}
private class TagData {
private final Object[] array;
private Map attributes;
private Object body;
public TagData(final Object args) {
this.array = (Object[])args;
}
public Map getAttributes() {
return attributes;
}
public Object getBody() {
return body;
}
public TagData invoke() {
attributes = null;
body = null;
for (Object o : array) {
if (o instanceof Map) {
attributes = (Map) o;
} else {
body = o;
}
}
return this;
}
}
public String toString() {
StringWriter wrt = new StringWriter(512);
try {
writeTo(wrt);
} catch (IOException e) {
ExceptionUtils.sneakyThrow(e);
}
return wrt.toString();
}
}