available.java

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/*
 *  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 org.apache.tools.ant.AntClassLoader;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.Task;
import org.apache.tools.ant.taskdefs.condition.Condition;
import org.apache.tools.ant.types.EnumeratedAttribute;
import org.apache.tools.ant.types.Path;
import org.apache.tools.ant.types.Reference;
import org.apache.tools.ant.util.FileUtils;
import org.apache.tools.ant.util.StringUtils;

/**
 * Will set the given property if the requested resource is available at
 * runtime. This task may also be used as a condition by the condition task.
 *
 * @since Ant 1.1
 *
 * @ant.task category="control"
 */
public class Available extends Task implements Condition {
    private static final FileUtils FILE_UTILS = FileUtils.getFileUtils();

    private String property;
    private String classname;
    private String filename;
    private File file;
    private Path filepath;
    private String resource;
    private FileDir type;
    private Path classpath;
    private AntClassLoader loader;
    private String value = "true";
    private boolean isTask = false;
    private boolean ignoreSystemclasses = false;
    private boolean searchParents   = false;

    /**
     * Set the searchParents attribute.
     * This controls the behaviour of the the "file" type.
     * If true, the path, parent path and grandparent path are
     * searched for the file. If false, only the path is seached.
     * The default value is false.
     * @param searchParents the value to set.
     */
    public void setSearchParents(boolean  searchParents) {
        this.searchParents = searchParents;
    }

    /**
     * Set the classpath to be used when searching for classes and resources.
     *
     * @param classpath an Ant Path object containing the search path.
     */
    public void setClasspath(Path classpath) {
        createClasspath().append(classpath);
    }

    /**
     * Classpath to be used when searching for classes and resources.
     *
     * @return an empty Path instance to be configured by Ant.
     */
    public Path createClasspath() {
        if (this.classpath == null) {
            this.classpath = new Path(getProject());
        }
        return this.classpath.createPath();
    }

    /**
     * Set the classpath by reference.
     *
     * @param r a Reference to a Path instance to be used as the classpath
     *          value.
     */
    public void setClasspathRef(Reference r) {
        createClasspath().setRefid(r);
    }

    /**
     * Set the path to use when looking for a file.
     *
     * @param filepath a Path instance containing the search path for files.
     */
    public void setFilepath(Path filepath) {
        createFilepath().append(filepath);
    }

    /**
     * Path to search for file resources.
     *
     * @return a new Path instance which Ant will configure with a file search
     *         path.
     */
    public Path createFilepath() {
        if (this.filepath == null) {
            this.filepath = new Path(getProject());
        }
        return this.filepath.createPath();
    }

    /**
     * Set the name of the property which will be set if the particular resource
     * is available.
     *
     * @param property the name of the property to set.
     */
    public void setProperty(String property) {
        this.property = property;
    }

    /**
     * Set the value to be given to the property if the desired resource is
     * available.
     *
     * @param value the value to be given.
     */
    public void setValue(String value) {
        this.value = value;
    }

    /**
     * Set a classname of a class which must be available to set the given
     * property.
     *
     * @param classname the name of the class required.
     */
    public void setClassname(String classname) {
        if (!"".equals(classname)) {
            this.classname = classname;
        }
    }

    /**
     * Set the file which must be present in the file system to set the given
     * property.
     *
     * @param file the name of the file which is required.
     */
    public void setFile(File file) {
        this.file = file;
        this.filename = FILE_UTILS.removeLeadingPath(getProject().getBaseDir(), file);
    }

    /**
     * Set the name of a Java resource which is required to set the property.
     *
     * @param resource the name of a resource which is required to be available.
     */
    public void setResource(String resource) {
        this.resource = resource;
    }

    /**
     * @deprecated since 1.5.x.
     *             setType(String) is deprecated and is replaced with
     *             setType(Available.FileDir) to make Ant's Introspection
     *             mechanism do the work and also to encapsulate operations on
     *             the type in its own class.
     * @param type the type of resource
     */
    public void setType(String type) {
        log("DEPRECATED - The setType(String) method has been deprecated."
            + " Use setType(Available.FileDir) instead.",
            Project.MSG_WARN);
        this.type = new FileDir();
        this.type.setValue(type);
    }

    /**
     * Set what type of file is required - either directory or file.
     *
     * @param type an instance of the FileDir enumeratedAttribute indicating
     *             whether the file required is to be a directory or a plain
     *             file.
     */
    public void setType(FileDir type) {
        this.type = type;
    }

    /**
     * Set whether the search for classes should ignore the runtime classes and
     * just use the given classpath.
     *
     * @param ignore true if system classes are to be ignored.
     */
    public void setIgnoresystemclasses(boolean ignore) {
        this.ignoreSystemclasses = ignore;
    }

    /**
     * Entry point when operating as a task.
     *
     * @exception BuildException if the task is not configured correctly.
     */
    public void execute() throws BuildException {
        if (property == null) {
            throw new BuildException("property attribute is required",
                                     getLocation());
        }

        isTask = true;
        try {
            if (eval()) {
                String oldvalue = getProject().getProperty(property);
                if (null != oldvalue && !oldvalue.equals(value)) {
                    log("DEPRECATED - <available> used to override an existing"
                        + " property."
                        + StringUtils.LINE_SEP
                        + "  Build file should not reuse the same property"
                        + " name for different values.",
                        Project.MSG_WARN);
                }
                // NB: this makes use of Project#setProperty rather than Project#setNewProperty
                //     due to backwards compatiblity reasons
                getProject().setProperty(property, value);
            }
        } finally {
            isTask = false;
        }
    }

    /**
     * Evaluate the availability of a resource.
     *
     * @return boolean is the resource is available.
     * @exception BuildException if the condition is not configured correctly
     */
    public boolean eval() throws BuildException {
        try {
            if (classname == null && file == null && resource == null) {
                throw new BuildException("At least one of (classname|file|"