Ant example source code file (AntStructure.java)

This example Ant source code file (AntStructure.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Ant tags/keywords

attlist, cdata, cdata, class, class, enumeration, hashtable, id, implied, implied, io, object, project, string, string, util

The AntStructure.java source code

/*
 *  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.tools.ant.taskdefs;

import java.io.File;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Vector;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.IntrospectionHelper;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.Task;
import org.apache.tools.ant.TaskContainer;
import org.apache.tools.ant.types.EnumeratedAttribute;
import org.apache.tools.ant.types.Reference;

/**
 * Creates a partial DTD for Ant from the currently known tasks.
 *
 *
 * @since Ant 1.1
 *
 * @ant.task category="xml"
 */
public class AntStructure extends Task {

    private static final String LINE_SEP
        = System.getProperty("line.separator");

    private File output;
    private StructurePrinter printer = new DTDPrinter();

    /**
     * The output file.
     * @param output the output file
     */
    public void setOutput(File output) {
        this.output = output;
    }

    /**
     * The StructurePrinter to use.
     * @param p the printer to use.
     * @since Ant 1.7
     */
    public void add(StructurePrinter p) {
        printer = p;
    }

    /**
     * Build the antstructure DTD.
     *
     * @exception BuildException if the DTD cannot be written.
     */
    public void execute() throws BuildException {

        if (output == null) {
            throw new BuildException("output attribute is required", getLocation());
        }

        PrintWriter out = null;
        try {
            try {
                out = new PrintWriter(new OutputStreamWriter(new FileOutputStream(output), "UTF8"));
            } catch (UnsupportedEncodingException ue) {
                /*
                 * Plain impossible with UTF8, see
                 * http://java.sun.com/j2se/1.5.0/docs/guide/intl/encoding.doc.html
                 *
                 * fallback to platform specific anyway.
                 */
                out = new PrintWriter(new FileWriter(output));
            }

            printer.printHead(out, getProject(),
                              getProject().getTaskDefinitions(),
                              getProject().getDataTypeDefinitions());

            printer.printTargetDecl(out);

            Enumeration dataTypes = getProject().getDataTypeDefinitions().keys();
            while (dataTypes.hasMoreElements()) {
                String typeName = (String) dataTypes.nextElement();
                printer.printElementDecl(
                    out, getProject(), typeName,
                    (Class) getProject().getDataTypeDefinitions().get(typeName));
            }

            Enumeration tasks = getProject().getTaskDefinitions().keys();
            while (tasks.hasMoreElements()) {
                String tName = (String) tasks.nextElement();
                printer.printElementDecl(out, getProject(), tName,
                                         (Class) getProject().getTaskDefinitions().get(tName));
            }

            printer.printTail(out);

        } catch (IOException ioe) {
            throw new BuildException("Error writing "
                                     + output.getAbsolutePath(), ioe, getLocation());
        } finally {
            if (out != null) {
                out.close();
            }
        }
    }

    /**
     * Writes the actual structure information.
     *
     * <p>{@link #printHead}, {@link #printTargetDecl} and {@link #printTail}
     * are called exactly once, {@link #printElementDecl} once for
     * each declared task and type.</p>
     */
    public static interface StructurePrinter {
        /**
         * Prints the header of the generated output.
         *
         * @param out PrintWriter to write to.
         * @param p Project instance for the current task
         * @param tasks map (name to implementing class)
         * @param types map (name to implementing class)
         * data types.
         */
        void printHead(PrintWriter out, Project p, Hashtable tasks,
                       Hashtable types);

        /**
         * Prints the definition for the target element.
         * @param out PrintWriter to write to.
         */
        void printTargetDecl(PrintWriter out);

        /**
         * Print the definition for a given element.
         *
         * @param out PrintWriter to write to.
         * @param p Project instance for the current task
         * @param name element name.
         * @param element class of the defined element.
         */
        void printElementDecl(PrintWriter out, Project p, String name,
                              Class element);

        /**
         * Prints the trailer.
         * @param out PrintWriter to write to.
         */
        void printTail(PrintWriter out);
    }

    private static class DTDPrinter implements StructurePrinter {

        private static final String BOOLEAN = "%boolean;";
        private static final String TASKS = "%tasks;";
        private static final String TYPES = "%types;";

        private Hashtable visited = new Hashtable();

        public void printTail(PrintWriter out) {
            visited.clear();
        }

        public void printHead(PrintWriter out, Project p, Hashtable tasks, Hashtable types) {
            printHead(out, tasks.keys(), types.keys());
        }


        /**
         * Prints the header of the generated output.
         *
         * <p>Basically this prints the XML declaration, defines some
         * entities and the project element.</p>
         */
        private void printHead(PrintWriter out, Enumeration tasks,
                               Enumeration types) {
            out.println("<?xml version=\"1.0\" encoding=\"UTF-8\" ?>");
            out.println("<!ENTITY % boolean \"(true|false|on|off|yes|no)\">");
            out.print("<!ENTITY % tasks \"");
            boolean first = true;
            while (tasks.hasMoreElements()) {
                String tName = (String) tasks.nextElement();
                if (!first) {
                    out.print(" | ");
                } else {
                    first = false;
                }
                out.print(tName);
            }
            out.println("\">");
            out.print("<!ENTITY % types \"");
            first = true;
            while (types.hasMoreElements()) {
                String typeName = (String) types.nextElement();
                if (!first) {
                    out.print(" | ");
                } else {
                    first = false;
                }
                out.print(typeName);
            }
            out.println("\">");

            out.println("");

            out.print("<!ELEMENT project (target | ");
            out.print(TASKS);
            out.print(" | ");
            out.print(TYPES);
            out.println(")*>");
            out.println("<!ATTLIST project");
            out.println("          name    CDATA #IMPLIED");
            out.println("          default CDATA #IMPLIED");
            out.println("          basedir CDATA #IMPLIED>");
            out.println("");
        }

        /**
         * Prints the definition for the target element.
         */
        public void printTargetDecl(PrintWriter out) {
            out.print("<!ELEMENT target (");
            out.print(TASKS);
            out.print(" | ");
            out.print(TYPES);
            out.println(")*>");
            out.println("");

            out.println("<!ATTLIST target");
            out.println("          id          ID    #IMPLIED");
            out.println("          name        CDATA #REQUIRED");
            out.println("          if          CDATA #IMPLIED");
            out.println("          unless      CDATA #IMPLIED");
            out.println("          depends     CDATA #IMPLIED");
            out.println("          description CDATA #IMPLIED>");
            out.println("");
        }

        /**
         * Print the definition for a given element.
         */
        public void printElementDecl(PrintWriter out, Project p,
                                     String name, Class element) {

            if (visited.containsKey(name)) {
                return;
            }
            visited.put(name, "");

            IntrospectionHelper ih = null;
            try {
                ih = IntrospectionHelper.getHelper(p, element);
            } catch (Throwable t) {
                /*
                 * XXX - failed to load the class properly.
                 *
                 * should we print a warning here?
                 */
                return;
            }

            StringBuffer sb = new StringBuffer("<!ELEMENT ");
            sb.append(name).append(" ");

            if (org.apache.tools.ant.types.Reference.class.equals(element)) {
                sb.append("EMPTY>").append(LINE_SEP);
                sb.append("<!ATTLIST ").append(name);
                sb.append(LINE_SEP).append("          id ID #IMPLIED");
                sb.append(LINE_SEP).append("          refid IDREF #IMPLIED");
                sb.append(">").append(LINE_SEP);
                out.println(sb);
                return;
            }

            Vector v = new Vector();
            if (ih.supportsCharacters()) {
                v.addElement("#PCDATA");
            }

            if (TaskContainer.class.isAssignableFrom(element)) {
                v.addElement(TASKS);
            }

            Enumeration e = ih.getNestedElements();
            while (e.hasMoreElements()) {
                v.addElement(e.nextElement());
            }

            if (v.isEmpty()) {
                sb.append("EMPTY");
            } else {
                sb.append("(");
                final int count = v.size();
                for (int i = 0; i < count; i++) {
                    if (i != 0) {
                        sb.append(" | ");
                    }
                    sb.append(v.elementAt(i));
                }
                sb.append(")");
                if (count > 1 || !v.elementAt(0).equals("#PCDATA")) {
                    sb.append("*");
                }
            }
            sb.append(">");
            out.println(sb);

            sb = new StringBuffer("<!ATTLIST ");
            sb.append(name);
            sb.append(LINE_SEP).append("          id ID #IMPLIED");

            e = ih.getAttributes();
            while (e.hasMoreElements()) {
                String attrName = (String) e.nextElement();
                if ("id".equals(attrName)) {
                    continue;
                }

                sb.append(LINE_SEP).append("          ")
                    .append(attrName).append(" ");
                Class type = ih.getAttributeType(attrName);
                if (type.equals(java.lang.Boolean.class)
                    || type.equals(java.lang.Boolean.TYPE)) {
                    sb.append(BOOLEAN).append(" ");
                } else if (Reference.class.isAssignableFrom(type)) {
                    sb.append("IDREF ");
                } else if (EnumeratedAttribute.class.isAssignableFrom(type)) {
                    try {
                        EnumeratedAttribute ea =
                            (EnumeratedAttribute) type.newInstance();
                        String[] values = ea.getValues();
                        if (values == null
                            || values.length == 0
                            || !areNmtokens(values)) {
                            sb.append("CDATA ");
                        } else {
                            sb.append("(");
                            for (int i = 0; i < values.length; i++) {
                                if (i != 0) {
                                    sb.append(" | ");
                                }
                                sb.append(values[i]);
                            }
                            sb.append(") ");
                        }
                    } catch (InstantiationException ie) {
                        sb.append("CDATA ");
                    } catch (IllegalAccessException ie) {
                        sb.append("CDATA ");
                    }
                } else if (type.getSuperclass() != null
                           && type.getSuperclass().getName().equals("java.lang.Enum")) {
                    try {
                        Object[] values = (Object[]) type.getMethod("values", (Class[])  null)
                            .invoke(null, (Object[]) null);
                        if (values.length == 0) {
                            sb.append("CDATA ");
                        } else {
                            sb.append('(');
                            for (int i = 0; i < values.length; i++) {
                                if (i != 0) {
                                    sb.append(" | ");
                                }
                                sb.append(type.getMethod("name", (Class[]) null)
                                          .invoke(values[i], (Object[]) null));
                            }
                            sb.append(") ");
                        }
                    } catch (Exception x) {
                        sb.append("CDATA ");
                    }
                } else {
                    sb.append("CDATA ");
                }
                sb.append("#IMPLIED");
            }
            sb.append(">").append(LINE_SEP);
            out.println(sb);

            final int count = v.size();
            for (int i = 0; i < count; i++) {
                String nestedName = (String) v.elementAt(i);
                if (!"#PCDATA".equals(nestedName)
                    && !TASKS.equals(nestedName)
                    && !TYPES.equals(nestedName)) {
                    printElementDecl(out, p, nestedName, ih.getElementType(nestedName));
                }
            }
        }

        /**
         * Does this String match the XML-NMTOKEN production?
         * @param s the string to test
         * @return true if the string matches the XML-NMTOKEN
         */
        public static final boolean isNmtoken(String s) {
            final int length = s.length();
            for (int i = 0; i < length; i++) {
                char c = s.charAt(i);
                // XXX - we are committing CombiningChar and Extender here
                if (!Character.isLetterOrDigit(c)
                    && c != '.' && c != '-' && c != '_' && c != ':') {
                    return false;
                }
            }
            return true;
        }

        /**
         * Do the Strings all match the XML-NMTOKEN production?
         *
         * <p>Otherwise they are not suitable as an enumerated attribute,
         * for example.</p>
         * @param s the array of string to test
         * @return true if all the strings in the array math XML-NMTOKEN
         */
        public static final boolean areNmtokens(String[] s) {
            for (int i = 0; i < s.length; i++) {
                if (!isNmtoken(s[i])) {
                    return false;
                }
            }
            return true;
        }
    }

    /**
     * Does this String match the XML-NMTOKEN production?
     * @param s the string to test
     * @return true if the string matches the XML-NMTOKEN
     */
    protected boolean isNmtoken(String s) {
        return DTDPrinter.isNmtoken(s);
    }

    /**
     * Do the Strings all match the XML-NMTOKEN production?
     *
     * <p>Otherwise they are not suitable as an enumerated attribute,
     * for example.</p>
     * @param s the array of string to test
     * @return true if all the strings in the array math XML-NMTOKEN
     */
    protected boolean areNmtokens(String[] s) {
        return DTDPrinter.areNmtokens(s);
    }
}