lesscss-java/src/main/java/org/lesscss/LessCompiler.java at master · buurd/lesscss-java · GitHub

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* 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 org.lesscss;

import java.io.File;

import java.io.IOException;

import java.io.InputStreamReader;

import java.net.URL;

import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

import org.apache.commons.io.FileUtils;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

import org.mozilla.javascript.Context;

import org.mozilla.javascript.Function;

import org.mozilla.javascript.JavaScriptException;

import org.mozilla.javascript.Scriptable;

import org.mozilla.javascript.ScriptableObject;

import org.mozilla.javascript.tools.shell.Global;

/**

* The LESS compiler to compile LESS sources to CSS stylesheets.

* <p>

* The compiler uses Rhino (JavaScript implementation written in Java), Envjs

* (simulated browser environment written in JavaScript), and the official LESS

* JavaScript compiler.<br />

* Note that the compiler is not a Java implementation of LESS itself, but rather

* integrates the LESS JavaScript compiler within a Java/JavaScript browser

* environment provided by Rhino and Envjs.

* </p>

* <p>

* The compiler comes bundled with the Envjs and LESS JavaScript, so there is

* no need to include them yourself. But if needed they can be overridden.

* </p>

* <h4>Basic code example:</h4>

* <pre>

* LessCompiler lessCompiler = new LessCompiler();

* String css = lessCompiler.compile("@color: #4D926F; #header { color: @color; }");

* </pre>

* @author Marcel Overdijk

* @see <a href="http://lesscss.org/">LESS - The Dynamic Stylesheet language</a>

* @see <a href="http://www.mozilla.org/rhino/">Rhino - JavaScript for Java</a>

* @see <a href="http://www.envjs.com/">Envjs - Bringing the Browser</a>

public class LessCompiler {

private static final String COMPILE_STRING = "function doIt(input, compress) { var result; var parser = new less.Parser(); parser.parse(input, function(e, tree) { if (e instanceof Object) { throw e; } ; result = tree.toCSS({compress: compress}); }); return result; }";

private static final Log log = LogFactory.getLog(LessCompiler.class);

private URL envJs = LessCompiler.class.getClassLoader().getResource("META-INF/env.rhino.js");

private URL lessJs = LessCompiler.class.getClassLoader().getResource("META-INF/less-1.3.3.min.js");

private List<URL> customJs = Collections.emptyList();

private boolean compress = false;

private String encoding = null;

private Function doIt;

private Scriptable scope;

/**

* Constructs a new <code>LessCompiler</code>.

public LessCompiler() {

}

/**

* Returns the Envjs JavaScript file used by the compiler.

* @return The Envjs JavaScript file used by the compiler.

public URL getEnvJs() {

return envJs;

}

/**

* Sets the Envjs JavaScript file used by the compiler.

* Must be set before {@link #init()} is called.

* @param envJs The Envjs JavaScript file used by the compiler.

public synchronized void setEnvJs(URL envJs) {

if (scope != null) {

throw new IllegalStateException("This method can only be called before init()");

}

this.envJs = envJs;

}

/**

* Returns the LESS JavaScript file used by the compiler.

* COMPILE_STRING

* @return The LESS JavaScript file used by the compiler.

public URL getLessJs() {

return lessJs;

}

/**

* Sets the LESS JavaScript file used by the compiler.

* Must be set before {@link #init()} is called.

* @param The LESS JavaScript file used by the compiler.

public synchronized void setLessJs(URL lessJs) {

if (scope != null) {

throw new IllegalStateException("This method can only be called before init()");

}

this.lessJs = lessJs;

}

/**

* Returns the custom JavaScript files used by the compiler.

* @return The custom JavaScript files used by the compiler.

public List<URL> getCustomJs() {

return Collections.unmodifiableList(customJs);

}

/**

* Sets a single custom JavaScript file used by the compiler.

* Must be set before {@link #init()} is called.

* @param customJs A single custom JavaScript file used by the compiler.

public synchronized void setCustomJs(URL customJs) {

if (scope != null) {

throw new IllegalStateException("This method can only be called before init()");

}

this.customJs = Collections.singletonList(customJs);

}

/**

* Sets the custom JavaScript files used by the compiler.

* Must be set before {@link #init()} is called.

* @param customJs The custom JavaScript files used by the compiler.

public synchronized void setCustomJs(List<URL> customJs) {

if (scope != null) {

throw new IllegalStateException("This method can only be called before init()");

}

// copy the list so there's no way for anyone else who holds a reference to the list to modify it

this.customJs = new ArrayList<URL>(customJs);

}

/**

* Returns whether the compiler will compress the CSS.

* @return Whether the compiler will compress the CSS.

public boolean isCompress() {

return compress;

}

/**

* Sets the compiler to compress the CSS.

* Must be set before {@link #init()} is called.

* @param compress If <code>true</code>, sets the compiler to compress the CSS.

public synchronized void setCompress(boolean compress) {

if (scope != null) {

throw new IllegalStateException("This method can only be called before init()");

}

this.compress = compress;

}

/**

* Returns the character encoding used by the compiler when writing the output <code>File</code>.

* @return The character encoding used by the compiler when writing the output <code>File</code>.

public String getEncoding() {

return encoding;

}

/**

* Sets the character encoding used by the compiler when writing the output <code>File</code>.

* If not set the platform default will be used.

* Must be set before {@link #init()} is called.

* @param The character encoding used by the compiler when writing the output <code>File</code>.

public synchronized void setEncoding(String encoding) {

if (scope != null) {

throw new IllegalStateException("This method can only be called before init()");

}

this.encoding = encoding;

}

/**

* Initializes this <code>LessCompiler</code>.

* <p>

* It is not needed to call this method manually, as it is called implicitly by the compile methods if needed.

* </p>

public synchronized void init() {

long start = System.currentTimeMillis();

try {

Context cx = Context.enter();

cx.setOptimizationLevel(-1);

cx.setLanguageVersion(Context.VERSION_1_7);

Global global = new Global();

global.init(cx);

scope = cx.initStandardObjects(global);

List<URL> jsUrls = new ArrayList<URL>(2 + customJs.size());

jsUrls.add(envJs);

jsUrls.add(lessJs);

jsUrls.addAll(customJs);

for(URL url : jsUrls){

InputStreamReader inputStreamReader = new InputStreamReader(url.openConnection().getInputStream());

try{

cx.evaluateReader(scope, inputStreamReader, url.toString(), 1, null);

}finally{

inputStreamReader.close();

}

doIt = cx.compileFunction(scope, COMPILE_STRING, "doIt.js", 1, null);

}

catch (Exception e) {

String message = "Failed to initialize LESS compiler.";

log.error(message, e);

throw new IllegalStateException(message, e);

}finally{

Context.exit();

}

if (log.isDebugEnabled()) {

log.debug("Finished initialization of LESS compiler in " + (System.currentTimeMillis() - start) + " ms.");

}

/**

* Compiles the LESS input <code>String</code> to CSS.

* @param input The LESS input <code>String</code> to compile.

* @return The CSS.

public String compile(String input) throws LessException {

synchronized(this){

if (scope == null) {

init();

}

long start = System.currentTimeMillis();

try {

Context cx = Context.enter();

Object result = doIt.call(cx, scope, null, new Object[]{input, compress});

if (log.isDebugEnabled()) {

log.debug("Finished compilation of LESS source in " + (System.currentTimeMillis() - start) + " ms.");

}

return result.toString();

}

catch (Exception e) {

if (e instanceof JavaScriptException) {

Scriptable value = (Scriptable)((JavaScriptException)e).getValue();

if (value != null && ScriptableObject.hasProperty(value, "message")) {

String message = ScriptableObject.getProperty(value, "message").toString();

throw new LessException(message, e);

}

throw new LessException(e);

}finally{

Context.exit();

}

/**

* Compiles the LESS input <code>File</code> to CSS.

* @param input The LESS input <code>File</code> to compile.

* @return The CSS.

* @throws IOException If the LESS file cannot be read.

public String compile(File input) throws IOException, LessException {

LessSource lessSource = new LessSource(input);

return compile(lessSource);

}

/**

* Compiles the LESS input <code>File</code> to CSS and writes it to the specified output <code>File</code>.

* @param input The LESS input <code>File</code> to compile.

* @param output The output <code>File</code> to write the CSS to.

* @throws IOException If the LESS file cannot be read or the output file cannot be written.

public void compile(File input, File output) throws IOException, LessException {

this.compile(input, output, true);

}

/**

* Compiles the LESS input <code>File</code> to CSS and writes it to the specified output <code>File</code>.

* @param input The LESS input <code>File</code> to compile.

* @param output The output <code>File</code> to write the CSS to.

* @param force 'false' to only compile the LESS input file in case the LESS source has been modified (including imports) or the output file does not exists.

* @throws IOException If the LESS file cannot be read or the output file cannot be written.

public void compile(File input, File output, boolean force) throws IOException, LessException {

LessSource lessSource = new LessSource(input);

compile(lessSource, output, force);

}

/**

* Compiles the input <code>LessSource</code> to CSS.

* @param input The input <code>LessSource</code> to compile.

* @return The CSS.

public String compile(LessSource input) throws LessException {

return compile(input.getNormalizedContent());

}

/**

* Compiles the input <code>LessSource</code> to CSS and writes it to the specified output <code>File</code>.

* @param input The input <code>LessSource</code> to compile.

* @param output The output <code>File</code> to write the CSS to.

* @throws IOException If the LESS file cannot be read or the output file cannot be written.

public void compile(LessSource input, File output) throws IOException, LessException {

compile(input, output, true);

}

/**

* Compiles the input <code>LessSource</code> to CSS and writes it to the specified output <code>File</code>.

* @param input The input <code>LessSource</code> to compile.

* @param output The output <code>File</code> to write the CSS to.

* @param force 'false' to only compile the input <code>LessSource</code> in case the LESS source has been modified (including imports) or the output file does not exists.

* @throws IOException If the LESS file cannot be read or the output file cannot be written.

public void compile(LessSource input, File output, boolean force) throws IOException, LessException {

if (force || !output.exists() || output.lastModified() < input.getLastModifiedIncludingImports()) {

String data = compile(input);

FileUtils.writeStringToFile(output, data, encoding);

}

lesscss-java/src/main/java/org/lesscss/LessCompiler.java at master · buurd/lesscss-java · GitHub

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