groovy.text.SimpleTemplateEngine Maven / Gradle / Ivy
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/*
* $Id: SimpleTemplateEngine.java 8271 2007-09-27 04:48:52Z paulk $
*
* Copyright 2003-2007 the original author or authors.
*
* 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 groovy.text;
import groovy.lang.Binding;
import groovy.lang.GroovyShell;
import groovy.lang.Script;
import groovy.lang.Writable;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.StringWriter;
import java.io.Writer;
import java.util.Map;
import org.codehaus.groovy.control.CompilationFailedException;
import org.codehaus.groovy.runtime.InvokerHelper;
/**
* This simple template engine uses JSP <% %> script and <%= %> expression syntax. It also lets you use normal groovy expressions in
* the template text much like the new JSP EL functionality. The variable 'out' is bound to the writer that the template is being written to.
*
* @author sam
* @author Christian Stein
* @author Paul King
*/
public class SimpleTemplateEngine extends TemplateEngine {
private boolean verbose;
private GroovyShell groovyShell;
public SimpleTemplateEngine() {
this(GroovyShell.class.getClassLoader());
}
public SimpleTemplateEngine(boolean verbose) {
this(GroovyShell.class.getClassLoader());
setVerbose(verbose);
}
public SimpleTemplateEngine(ClassLoader parentLoader) {
this(new GroovyShell(parentLoader));
}
public SimpleTemplateEngine(GroovyShell groovyShell) {
this.groovyShell = groovyShell;
}
public Template createTemplate(Reader reader) throws CompilationFailedException, IOException {
SimpleTemplate template = new SimpleTemplate();
String script = template.parse(reader);
if (verbose) {
System.out.println("\n-- script source --");
System.out.print(script);
System.out.println("\n-- script end --\n");
}
template.script = groovyShell.parse(script);
return template;
}
public void setVerbose(boolean verbose) {
this.verbose = verbose;
}
public boolean isVerbose() {
return verbose;
}
private static class SimpleTemplate implements Template {
protected Script script;
public Writable make() {
return make(null);
}
public Writable make(final Map map) {
return new Writable() {
/**
* Write the template document with the set binding applied to the writer.
*
* @see groovy.lang.Writable#writeTo(java.io.Writer)
*/
public Writer writeTo(Writer writer) {
Binding binding;
if (map == null)
binding = new Binding();
else
binding = new Binding(map);
Script scriptObject = InvokerHelper.createScript(script.getClass(), binding);
PrintWriter pw = new PrintWriter(writer);
scriptObject.setProperty("out", pw);
scriptObject.run();
pw.flush();
return writer;
}
/**
* Convert the template and binding into a result String.
*
* @see java.lang.Object#toString()
*/
public String toString() {
try {
StringWriter sw = new StringWriter();
writeTo(sw);
return sw.toString();
} catch (Exception e) {
return e.toString();
}
}
};
}
/**
* Parse the text document looking for <% or <%= and then call out to the appropriate handler, otherwise copy the text directly
* into the script while escaping quotes.
*
* @param reader a reader for the template text
* @return the parsed text
* @throws IOException if something goes wrong
*/
protected String parse(Reader reader) throws IOException {
if (!reader.markSupported()) {
reader = new BufferedReader(reader);
}
StringWriter sw = new StringWriter();
startScript(sw);
int c;
while ((c = reader.read()) != -1) {
if (c == '<') {
reader.mark(1);
c = reader.read();
if (c != '%') {
sw.write('<');
reader.reset();
} else {
reader.mark(1);
c = reader.read();
if (c == '=') {
groovyExpression(reader, sw);
} else {
reader.reset();
groovySection(reader, sw);
}
}
continue; // at least '<' is consumed ... read next chars.
}
if (c == '\"') {
sw.write('\\');
}
/*
* Handle raw new line characters.
*/
if (c == '\n' || c == '\r') {
if (c == '\r') { // on Windows, "\r\n" is a new line.
reader.mark(1);
c = reader.read();
if (c != '\n') {
reader.reset();
}
}
sw.write("\\n\");\nout.print(\"");
continue;
}
sw.write(c);
}
endScript(sw);
return sw.toString();
}
private void startScript(StringWriter sw) {
sw.write("/* Generated by SimpleTemplateEngine */\n");
sw.write("out.print(\"");
}
private void endScript(StringWriter sw) {
sw.write("\");\n");
}
/**
* Closes the currently open write and writes out the following text as a GString expression until it reaches an end %>.
*
* @param reader a reader for the template text
* @param sw a StringWriter to write expression content
* @throws IOException if something goes wrong
*/
private void groovyExpression(Reader reader, StringWriter sw) throws IOException {
sw.write("\");out.print(\"${");
int c;
while ((c = reader.read()) != -1) {
if (c == '%') {
c = reader.read();
if (c != '>') {
sw.write('%');
} else {
break;
}
}
if (c != '\n' && c != '\r') {
sw.write(c);
}
}
sw.write("}\");\nout.print(\"");
}
/**
* Closes the currently open write and writes the following text as normal Groovy script code until it reaches an end %>.
*
* @param reader a reader for the template text
* @param sw a StringWriter to write expression content
* @throws IOException if something goes wrong
*/
private void groovySection(Reader reader, StringWriter sw) throws IOException {
sw.write("\");");
int c;
while ((c = reader.read()) != -1) {
if (c == '%') {
c = reader.read();
if (c != '>') {
sw.write('%');
} else {
break;
}
}
/* Don't eat EOL chars in sections - as they are valid instruction separators.
* See http://jira.codehaus.org/browse/GROOVY-980
*/
// if (c != '\n' && c != '\r') {
sw.write(c);
//}
}
sw.write(";\nout.print(\"");
}
}
}