Java tutorial
/** * 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 org.apache.hadoop.yarn.webapp.hamlet; import com.google.common.collect.Sets; import java.io.IOException; import java.io.PrintWriter; import java.lang.annotation.Annotation; import java.lang.reflect.Method; import java.lang.reflect.ParameterizedType; import java.lang.reflect.Type; import java.util.Set; import java.util.regex.Pattern; import org.apache.commons.cli.CommandLine; import org.apache.commons.cli.GnuParser; import org.apache.commons.cli.HelpFormatter; import org.apache.commons.cli.Options; import org.apache.hadoop.classification.InterfaceAudience; import org.apache.hadoop.util.StringUtils; import org.apache.hadoop.yarn.webapp.WebAppException; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * Generates a specific hamlet implementation class from a spec class * using a generic hamlet implementation class. */ @InterfaceAudience.LimitedPrivate({ "YARN", "MapReduce" }) public class HamletGen { static final Logger LOG = LoggerFactory.getLogger(HamletGen.class); static final Options opts = new Options(); static { opts.addOption("h", "help", false, "Print this help message") .addOption("s", "spec-class", true, "The class that holds the spec interfaces. e.g. HamletSpec") .addOption("i", "impl-class", true, "An implementation class. e.g. HamletImpl") .addOption("o", "output-class", true, "Output class name") .addOption("p", "output-package", true, "Output package name"); }; static final Pattern elementRegex = Pattern.compile("^[A-Z][A-Z0-9]*$"); int bytes = 0; PrintWriter out; final Set<String> endTagOptional = Sets.newHashSet(); final Set<String> inlineElements = Sets.newHashSet(); Class<?> top; // html top-level interface String hamlet; // output class simple name; boolean topMode; /** * Generate a specific Hamlet implementation from a spec. * @param specClass holds hamlet interfaces. e.g. {@link HamletSpec} * @param implClass a generic hamlet implementation. e.g. {@link HamletImpl} * @param outputName name of the output class. e.g. {@link Hamlet} * @param outputPkg package name of the output class. * @throws IOException */ public void generate(Class<?> specClass, Class<?> implClass, String outputName, String outputPkg) throws IOException { LOG.info("Generating {} using {} and {}", new Object[] { outputName, specClass, implClass }); out = new PrintWriter(outputName + ".java", "UTF-8"); hamlet = basename(outputName); String pkg = pkgName(outputPkg, implClass.getPackage().getName()); puts(0, "// Generated by HamletGen. Do NOT edit!\n", "package ", pkg, ";\n", "import java.io.PrintWriter;\n", "import java.util.EnumSet;\n", "import static java.util.EnumSet.*;\n", "import static ", implClass.getName(), ".EOpt.*;\n", "import org.apache.hadoop.yarn.webapp.SubView;"); String implClassName = implClass.getSimpleName(); if (!implClass.getPackage().getName().equals(pkg)) { puts(0, "import ", implClass.getName(), ';'); } puts(0, "\n", "public class ", hamlet, " extends ", implClassName, " implements ", specClass.getSimpleName(), "._Html {\n", " public ", hamlet, "(PrintWriter out, int nestLevel,", " boolean wasInline) {\n", " super(out, nestLevel, wasInline);\n", " }\n\n", // inline is context sensitive " static EnumSet<EOpt> opt(boolean endTag, boolean inline, ", "boolean pre) {\n", " EnumSet<EOpt> opts = of(ENDTAG);\n", " if (!endTag) opts.remove(ENDTAG);\n", " if (inline) opts.add(INLINE);\n", " if (pre) opts.add(PRE);\n", " return opts;\n", " }"); initLut(specClass); genImpl(specClass, implClassName, 1); LOG.info("Generating {} methods", hamlet); genMethods(hamlet, top, 1); puts(0, "}"); out.close(); LOG.info("Wrote {} bytes to {}.java", bytes, outputName); } String basename(String path) { return path.substring(path.lastIndexOf('/') + 1); } String pkgName(String pkg, String defaultPkg) { if (pkg == null || pkg.isEmpty()) return defaultPkg; return pkg; } void initLut(Class<?> spec) { endTagOptional.clear(); inlineElements.clear(); for (Class<?> cls : spec.getClasses()) { Annotation a = cls.getAnnotation(HamletSpec.Element.class); if (a != null && !((HamletSpec.Element) a).endTag()) { endTagOptional.add(cls.getSimpleName()); } if (cls.getSimpleName().equals("Inline")) { for (Method method : cls.getMethods()) { String retName = method.getReturnType().getSimpleName(); if (isElement(retName)) { inlineElements.add(retName); } } } } } void genImpl(Class<?> spec, String implClassName, int indent) { String specName = spec.getSimpleName(); for (Class<?> cls : spec.getClasses()) { String className = cls.getSimpleName(); if (cls.isInterface()) { genFactoryMethods(cls, indent); } if (isElement(className)) { LOG.info("Generating class {}<T>", className); puts(indent, "\n", "public class ", className, "<T extends _>", " extends EImp<T> implements ", specName, ".", className, " {\n", " public ", className, "(String name, T parent,", " EnumSet<EOpt> opts) {\n", " super(name, parent, opts);\n", " }"); genMethods(className, cls, indent + 1); puts(indent, "}"); } else if (className.equals("_Html")) { top = cls; } } } void genFactoryMethods(Class<?> cls, int indent) { for (Method method : cls.getDeclaredMethods()) { String retName = method.getReturnType().getSimpleName(); String methodName = method.getName(); if (methodName.charAt(0) == '$') continue; if (isElement(retName) && method.getParameterTypes().length == 0) { genFactoryMethod(retName, methodName, indent); } } } void genMethods(String className, Class<?> cls, int indent) { topMode = (top != null && cls.equals(top)); for (Method method : cls.getMethods()) { String retName = method.getReturnType().getSimpleName(); if (method.getName().charAt(0) == '$') { genAttributeMethod(className, method, indent); } else if (isElement(retName)) { genNewElementMethod(className, method, indent); } else { genCurElementMethod(className, method, indent); } } } void genAttributeMethod(String className, Method method, int indent) { String methodName = method.getName(); String attrName = methodName.substring(1).replace('_', '-'); Type[] params = method.getGenericParameterTypes(); echo(indent, "\n", "@Override\n", "public ", className, topMode ? " " : "<T> ", methodName, "("); if (params.length == 0) { puts(0, ") {"); puts(indent, " addAttr(\"", attrName, "\", null);\n", " return this;\n", "}"); } else if (params.length == 1) { String typeName = getTypeName(params[0]); puts(0, typeName, " value) {"); if (typeName.equals("EnumSet<LinkType>")) { puts(indent, " addRelAttr(\"", attrName, "\", value);\n", " return this;\n", "}"); } else if (typeName.equals("EnumSet<Media>")) { puts(indent, " addMediaAttr(\"", attrName, "\", value);\n", " return this;\n", "}"); } else { puts(indent, " addAttr(\"", attrName, "\", value);\n", " return this;\n", "}"); } } else { throwUnhandled(className, method); } } String getTypeName(Type type) { if (type instanceof Class<?>) { return ((Class<?>) type).getSimpleName(); } ParameterizedType pt = (ParameterizedType) type; return ((Class<?>) pt.getRawType()).getSimpleName() + "<" + ((Class<?>) pt.getActualTypeArguments()[0]).getSimpleName() + ">"; } void genFactoryMethod(String retName, String methodName, int indent) { puts(indent, "\n", "private <T extends _> ", retName, "<T> ", methodName, "_(T e, boolean inline) {\n", " return new ", retName, "<T>(\"", StringUtils.toLowerCase(retName), "\", e, opt(", !endTagOptional.contains(retName), ", inline, ", retName.equals("PRE"), ")); }"); } void genNewElementMethod(String className, Method method, int indent) { String methodName = method.getName(); String retName = method.getReturnType().getSimpleName(); Class<?>[] params = method.getParameterTypes(); echo(indent, "\n", "@Override\n", "public ", retName, "<", className, topMode ? "> " : "<T>> ", methodName, "("); if (params.length == 0) { puts(0, ") {"); puts(indent, topMode ? "" : " closeAttrs();\n", " return ", StringUtils.toLowerCase(retName), "_" + "(this, ", isInline(className, retName), ");\n", "}"); } else if (params.length == 1) { puts(0, "String selector) {"); puts(indent, " return setSelector(", methodName, "(), selector);\n", "}"); } else { throwUnhandled(className, method); } } boolean isInline(String container, String className) { if ((container.equals("BODY") || container.equals(hamlet) || container.equals("HEAD") || container.equals("HTML")) && (className.equals("INS") || className.equals("DEL") || className.equals("SCRIPT"))) { return false; } return inlineElements.contains(className); } void genCurElementMethod(String className, Method method, int indent) { String methodName = method.getName(); Class<?>[] params = method.getParameterTypes(); if (topMode || params.length > 0) { echo(indent, "\n", "@Override\n", "public ", className, topMode ? " " : "<T> ", methodName, "("); } if (params.length == 0) { if (topMode) { puts(0, ") {"); puts(indent, " return this;\n", "}"); } } else if (params.length == 1) { if (methodName.equals("base")) { puts(0, "String href) {"); puts(indent, " return base().$href(href)._();\n", "}"); } else if (methodName.equals("script")) { puts(0, "String src) {"); puts(indent, " return setScriptSrc(script(), src)._();\n", "}"); } else if (methodName.equals("style")) { puts(0, "Object... lines) {"); puts(indent, " return style().$type(\"text/css\")._(lines)._();\n", "}"); } else if (methodName.equals("img")) { puts(0, "String src) {"); puts(indent, " return ", methodName, "().$src(src)._();\n", "}"); } else if (methodName.equals("br") || methodName.equals("hr") || methodName.equals("col")) { puts(0, "String selector) {"); puts(indent, " return setSelector(", methodName, "(), selector)._();\n", "}"); } else if (methodName.equals("link")) { puts(0, "String href) {"); puts(indent, " return setLinkHref(", methodName, "(), href)._();\n", "}"); } else if (methodName.equals("_")) { if (params[0].getSimpleName().equals("Class")) { puts(0, "Class<? extends SubView> cls) {"); puts(indent, " ", topMode ? "subView" : "_v", "(cls);\n", " return this;\n", "}"); } else { puts(0, "Object... lines) {"); puts(indent, " _p(", needsEscaping(className), ", lines);\n", " return this;\n", "}"); } } else if (methodName.equals("_r")) { puts(0, "Object... lines) {"); puts(indent, " _p(false, lines);\n", " return this;\n", "}"); } else { puts(0, "String cdata) {"); puts(indent, " return ", methodName, "()._(cdata)._();\n", "}"); } } else if (params.length == 2) { if (methodName.equals("meta")) { puts(0, "String name, String content) {"); puts(indent, " return meta().$name(name).$content(content)._();\n", "}"); } else if (methodName.equals("meta_http")) { puts(0, "String header, String content) {"); puts(indent, " return meta().$http_equiv(header).$content(content)._();\n", "}"); } else if (methodName.equals("a")) { puts(0, "String href, String anchorText) {"); puts(indent, " return a().$href(href)._(anchorText)._();\n", "}"); } else if (methodName.equals("bdo")) { puts(0, "Dir dir, String cdata) {"); puts(indent, " return bdo().$dir(dir)._(cdata)._();\n", "}"); } else if (methodName.equals("label")) { puts(0, "String forId, String cdata) {"); puts(indent, " return label().$for(forId)._(cdata)._();\n", "}"); } else if (methodName.equals("param")) { puts(0, "String name, String value) {"); puts(indent, " return param().$name(name).$value(value)._();\n", "}"); } else { puts(0, "String selector, String cdata) {"); puts(indent, " return setSelector(", methodName, "(), selector)._(cdata)._();\n", "}"); } } else if (params.length == 3) { if (methodName.equals("a")) { puts(0, "String selector, String href, String anchorText) {"); puts(indent, " return setSelector(a(), selector)", ".$href(href)._(anchorText)._();\n", "}"); } } else { throwUnhandled(className, method); } } static boolean needsEscaping(String eleName) { return !eleName.equals("SCRIPT") && !eleName.equals("STYLE"); } static void throwUnhandled(String className, Method method) { throw new WebAppException("Unhandled " + className + "#" + method); } void echo(int indent, Object... args) { String prev = null; for (Object o : args) { String s = String.valueOf(o); if (!s.isEmpty() && !s.equals("\n") && (prev == null || prev.endsWith("\n"))) { indent(indent); } prev = s; out.print(s); bytes += s.length(); } } void indent(int indent) { for (int i = 0; i < indent; ++i) { out.print(" "); bytes += 2; } } void puts(int indent, Object... args) { echo(indent, args); out.println(); ++bytes; } boolean isElement(String s) { return elementRegex.matcher(s).matches(); } public static void main(String[] args) throws Exception { CommandLine cmd = new GnuParser().parse(opts, args); if (cmd.hasOption("help")) { new HelpFormatter().printHelp("Usage: hbgen [OPTIONS]", opts); return; } // defaults Class<?> specClass = HamletSpec.class; Class<?> implClass = HamletImpl.class; String outputClass = "HamletTmp"; String outputPackage = implClass.getPackage().getName(); if (cmd.hasOption("spec-class")) { specClass = Class.forName(cmd.getOptionValue("spec-class")); } if (cmd.hasOption("impl-class")) { implClass = Class.forName(cmd.getOptionValue("impl-class")); } if (cmd.hasOption("output-class")) { outputClass = cmd.getOptionValue("output-class"); } if (cmd.hasOption("output-package")) { outputPackage = cmd.getOptionValue("output-package"); } new HamletGen().generate(specClass, implClass, outputClass, outputPackage); } }