org.apache.ant/ant/1.10.7 : org/apache/tools/ant/ProjectHelper.java

ProjectHelper
https://ant.apache.org/: master POM (The Apache Software Foundation)
The Apache Software License, Version 2.0
/*
 *  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
 *
 *      https://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;

import java.io.File;
import java.util.Hashtable;
import java.util.LinkedList;
import java.util.List;
import java.util.Locale;
import java.util.Vector;

import org.apache.tools.ant.types.Resource;
import org.apache.tools.ant.types.resources.FileResource;
import org.apache.tools.ant.util.LoaderUtils;
import org.xml.sax.AttributeList;

Configures a Project (complete with Targets and Tasks) based on
a build file. It'll rely on a plugin to do the actual processing
of the file.

This class also provide static wrappers for common introspection.
/**
 * Configures a Project (complete with Targets and Tasks) based on
 * a build file. It'll rely on a plugin to do the actual processing
 * of the file.
 * <p>
 * This class also provide static wrappers for common introspection.
 */
public class ProjectHelper {
    The URI for ant name space /** The URI for ant name space */
    public static final String ANT_CORE_URI    = "antlib:org.apache.tools.ant";

    The URI for antlib current definitions /** The URI for antlib current definitions */
    public static final String ANT_CURRENT_URI      = "ant:current";

    The URI for ant specific attributes
Since: Ant 1.9.1/** The URI for ant specific attributes
     * @since Ant 1.9.1
     * */
    public static final String ANT_ATTRIBUTE_URI      = "ant:attribute";

    The URI for defined types/tasks - the format is antlib:<package> /** The URI for defined types/tasks - the format is antlib:&lt;package&gt; */
    public static final String ANTLIB_URI     = "antlib:";

    Polymorphic attribute  /** Polymorphic attribute  */
    public static final String ANT_TYPE = "ant-type";

    Name of JVM system property which provides the name of the
ProjectHelper class to use.
/**
     * Name of JVM system property which provides the name of the
     * ProjectHelper class to use.
     */
    public static final String HELPER_PROPERTY = MagicNames.PROJECT_HELPER_CLASS;

    The service identifier in jars which provide Project Helper
implementations.
/**
     * The service identifier in jars which provide Project Helper
     * implementations.
     */
    public static final String SERVICE_ID = MagicNames.PROJECT_HELPER_SERVICE;

    name of project helper reference that we add to a project
/**
     * name of project helper reference that we add to a project
     */
    public static final String PROJECTHELPER_REFERENCE = MagicNames.REFID_PROJECT_HELPER;

    constant to denote use project name as target prefix
Since: Ant 1.9.1/**
     * constant to denote use project name as target prefix
     * @since Ant 1.9.1
     */
    public static final String USE_PROJECT_NAME_AS_TARGET_PREFIX = "USE_PROJECT_NAME_AS_TARGET_PREFIX";

    Configures the project with the contents of the specified build file.
Params: project – The project to configure. Must not be null.
buildFile – A build file giving the project's configuration.
                 Must not be null.
Throws: BuildException – if the configuration is invalid or cannot be read/**
     * Configures the project with the contents of the specified build file.
     *
     * @param project The project to configure. Must not be <code>null</code>.
     * @param buildFile A build file giving the project's configuration.
     *                  Must not be <code>null</code>.
     *
     * @exception BuildException if the configuration is invalid or cannot be read
     */
    public static void configureProject(Project project, File buildFile) throws BuildException {
        FileResource resource = new FileResource(buildFile);
        ProjectHelper helper = ProjectHelperRepository.getInstance().getProjectHelperForBuildFile(resource);
        project.addReference(PROJECTHELPER_REFERENCE, helper);
        helper.parse(project, buildFile);
    }

    Possible value for target's onMissingExtensionPoint attribute. It determines how to deal with
targets that want to extend missing extension-points.

This class behaves like a Java 1.5 Enum class.
Since: 1.8.2/**
     * Possible value for target's onMissingExtensionPoint attribute. It determines how to deal with
     * targets that want to extend missing extension-points.
     * <p>
     * This class behaves like a Java 1.5 Enum class.
     *
     * @since 1.8.2
     */
    public static final class OnMissingExtensionPoint {

        fail if the extension-point is not defined /** fail if the extension-point is not defined */
        public static final OnMissingExtensionPoint FAIL = new OnMissingExtensionPoint(
                "fail");

        warn if the extension-point is not defined /** warn if the extension-point is not defined */
        public static final OnMissingExtensionPoint WARN = new OnMissingExtensionPoint(
                "warn");

        ignore the extensionOf attribute if the extension-point is not defined /** ignore the extensionOf attribute if the extension-point is not defined */
        public static final OnMissingExtensionPoint IGNORE = new OnMissingExtensionPoint(
                "ignore");

        private static final OnMissingExtensionPoint[] values = new OnMissingExtensionPoint[] {
                                FAIL, WARN, IGNORE };

        private final String name;

        private OnMissingExtensionPoint(String name) {
            this.name = name;
        }

        public String name() {
            return name;
        }

        public String toString() {
            return name;
        }

        public static OnMissingExtensionPoint valueOf(String name) {
            if (name == null) {
                throw new NullPointerException();
            }
            for (OnMissingExtensionPoint value : values) {
                if (name.equals(value.name())) {
                    return value;
                }
            }
            throw new IllegalArgumentException(
                    "Unknown onMissingExtensionPoint " + name);
        }
    }

    // -------------------- Common properties  --------------------
    // The following properties are required by import (and other tasks
    // that read build files using ProjectHelper).

    private Vector<Object> importStack = new Vector<>();
    private List<String[]> extensionStack = new LinkedList<>();

     Import stack.
 Used to keep track of imported files. Error reporting should
 display the import path.
Returns: the stack of import source objects./**
     *  Import stack.
     *  Used to keep track of imported files. Error reporting should
     *  display the import path.
     *
     * @return the stack of import source objects.
     */
    public Vector<Object> getImportStack() {
        return importStack;
    }

    Extension stack.
Used to keep track of targets that extend extension points.
Returns: a list of three element string arrays where the first element is the name of the extensionpoint, the second the name of the target and the third the name of the enum like class OnMissingExtensionPoint./**
     * Extension stack.
     * Used to keep track of targets that extend extension points.
     *
     * @return a list of three element string arrays where the first
     * element is the name of the extensionpoint, the second the name
     * of the target and the third the name of the enum like class
     * {@link OnMissingExtensionPoint}.
     */
    public List<String[]> getExtensionStack() {
        return extensionStack;
    }

    private static final ThreadLocal<String> targetPrefix = new ThreadLocal<>();

    The prefix to prepend to imported target names.
May be set by <import>'s as attribute.
Returns: the configured prefix or null
Since: Ant 1.8.0/**
     * The prefix to prepend to imported target names.
     *
     * <p>May be set by &lt;import&gt;'s as attribute.</p>
     *
     * @return the configured prefix or null
     *
     * @since Ant 1.8.0
     */
    public static String getCurrentTargetPrefix() {
        return targetPrefix.get();
    }

    Sets the prefix to prepend to imported target names.
Params: prefix – String
Since: Ant 1.8.0/**
     * Sets the prefix to prepend to imported target names.
     *
     * @param prefix String
     * @since Ant 1.8.0
     */
    public static void setCurrentTargetPrefix(String prefix) {
        targetPrefix.set(prefix);
    }

    private static final ThreadLocal<String> prefixSeparator = ThreadLocal.withInitial(() -> ".");

    The separator between the prefix and the target name.
May be set by <import>'s prefixSeparator attribute.
Returns: String
Since: Ant 1.8.0/**
     * The separator between the prefix and the target name.
     *
     * <p>May be set by &lt;import&gt;'s prefixSeparator attribute.</p>
     *
     * @return String
     * @since Ant 1.8.0
     */
    public static String getCurrentPrefixSeparator() {
        return prefixSeparator.get();
    }

    Sets the separator between the prefix and the target name.
Params: sep – String
Since: Ant 1.8.0/**
     * Sets the separator between the prefix and the target name.
     *
     * @param sep String
     * @since Ant 1.8.0
     */
    public static void setCurrentPrefixSeparator(String sep) {
        prefixSeparator.set(sep);
    }

    private static final ThreadLocal<Boolean> inIncludeMode = ThreadLocal.withInitial(() -> Boolean.FALSE);

    Whether the current file should be read in include as opposed
to import mode.
In include mode included targets are only known by their
prefixed names and their depends lists get rewritten so that
all dependencies get the prefix as well.
In import mode imported targets are known by an adorned as
well as a prefixed name and the unadorned target may be
overwritten in the importing build file.  The depends list of
the imported targets is not modified at all.
Returns: boolean
Since: Ant 1.8.0/**
     * Whether the current file should be read in include as opposed
     * to import mode.
     *
     * <p>In include mode included targets are only known by their
     * prefixed names and their depends lists get rewritten so that
     * all dependencies get the prefix as well.</p>
     *
     * <p>In import mode imported targets are known by an adorned as
     * well as a prefixed name and the unadorned target may be
     * overwritten in the importing build file.  The depends list of
     * the imported targets is not modified at all.</p>
     *
     * @return boolean
     * @since Ant 1.8.0
     */
    public static boolean isInIncludeMode() {
        return Boolean.TRUE.equals(inIncludeMode.get());
    }

    Sets whether the current file should be read in include as
opposed to import mode.
Params: includeMode – boolean
Since: Ant 1.8.0/**
     * Sets whether the current file should be read in include as
     * opposed to import mode.
     *
     * @param includeMode boolean
     * @since Ant 1.8.0
     */
    public static void setInIncludeMode(boolean includeMode) {
        inIncludeMode.set(includeMode);
    }

    // --------------------  Parse method  --------------------
    Parses the project file, configuring the project as it goes.
Params: project – The project for the resulting ProjectHelper to configure.
               Must not be null.
source – The source for XML configuration. A helper must support
              at least File, for backward compatibility. Helpers may
              support URL, InputStream, etc or specialized types.
Throws: BuildException – if the configuration is invalid or cannot
                          be read
Since: Ant1.5/**
     * Parses the project file, configuring the project as it goes.
     *
     * @param project The project for the resulting ProjectHelper to configure.
     *                Must not be <code>null</code>.
     * @param source The source for XML configuration. A helper must support
     *               at least File, for backward compatibility. Helpers may
     *               support URL, InputStream, etc or specialized types.
     *
     * @since Ant1.5
     * @exception BuildException if the configuration is invalid or cannot
     *                           be read
     */
    public void parse(Project project, Object source) throws BuildException {
        throw new BuildException("ProjectHelper.parse() must be implemented "
            + "in a helper plugin " + this.getClass().getName());
    }

    Get the first project helper found in the classpath
See Also: ProjectHelperRepository.getHelpers()
Returns: an project helper, never null/**
     * Get the first project helper found in the classpath
     *
     * @return an project helper, never <code>null</code>
     * @see org.apache.tools.ant.ProjectHelperRepository#getHelpers()
     */
    public static ProjectHelper getProjectHelper() {
        return ProjectHelperRepository.getInstance().getHelpers().next();
    }

    JDK1.1 compatible access to the context class loader. Cut & paste from JAXP.
Deprecated: since 1.6.x.
            Use LoaderUtils.getContextClassLoader()
Returns: the current context class loader, or null
if the context class loader is unavailable./**
     * JDK1.1 compatible access to the context class loader. Cut &amp; paste from JAXP.
     *
     * @deprecated since 1.6.x.
     *             Use LoaderUtils.getContextClassLoader()
     *
     * @return the current context class loader, or <code>null</code>
     * if the context class loader is unavailable.
     */
    @Deprecated
    public static ClassLoader getContextClassLoader() {
        return LoaderUtils.isContextLoaderAvailable() ? LoaderUtils.getContextClassLoader() : null;
    }

    // -------------------- Static utils, used by most helpers ----------------

    Configures an object using an introspection handler.
Params: target – The target object to be configured.
              Must not be null.
attrs –  A list of attributes to configure within the target.
              Must not be null.
project – The project containing the target.
               Must not be null.
Throws: BuildException – if any of the attributes can't be handled by
                          the target
Deprecated: since 1.6.x.
            Use IntrospectionHelper for each property./**
     * Configures an object using an introspection handler.
     *
     * @param target The target object to be configured.
     *               Must not be <code>null</code>.
     * @param attrs  A list of attributes to configure within the target.
     *               Must not be <code>null</code>.
     * @param project The project containing the target.
     *                Must not be <code>null</code>.
     *
     * @deprecated since 1.6.x.
     *             Use IntrospectionHelper for each property.
     *
     * @exception BuildException if any of the attributes can't be handled by
     *                           the target
     */
    @Deprecated
    public static void configure(Object target, AttributeList attrs,
                                 Project project) throws BuildException {
        if (target instanceof TypeAdapter) {
            target = ((TypeAdapter) target).getProxy();
        }
        IntrospectionHelper ih = IntrospectionHelper.getHelper(project, target.getClass());

        for (int i = 0, length = attrs.getLength(); i < length; i++) {
            // reflect these into the target
            String value = replaceProperties(project, attrs.getValue(i), project.getProperties());
            try {
                ih.setAttribute(project, target, attrs.getName(i).toLowerCase(Locale.ENGLISH), value);
            } catch (BuildException be) {
                // id attribute must be set externally
                if (!attrs.getName(i).equals("id")) {
                    throw be;
                }
            }
        }
    }

    Adds the content of #PCDATA sections to an element.
Params: project – The project containing the target.
               Must not be null.
target –  The target object to be configured.
               Must not be null.
buf – A character array of the text within the element.
           Will not be null.
start – The start element in the array.
count – The number of characters to read from the array.
Throws: BuildException – if the target object doesn't accept text/**
     * Adds the content of #PCDATA sections to an element.
     *
     * @param project The project containing the target.
     *                Must not be <code>null</code>.
     * @param target  The target object to be configured.
     *                Must not be <code>null</code>.
     * @param buf A character array of the text within the element.
     *            Will not be <code>null</code>.
     * @param start The start element in the array.
     * @param count The number of characters to read from the array.
     *
     * @exception BuildException if the target object doesn't accept text
     */
    public static void addText(Project project, Object target, char[] buf,
        int start, int count) throws BuildException {
        addText(project, target, new String(buf, start, count));
    }

    Adds the content of #PCDATA sections to an element.
Params: project – The project containing the target.
               Must not be null.
target –  The target object to be configured.
               Must not be null.
text –    Text to add to the target.
               May be null, in which case this
               method call is a no-op.
Throws: BuildException – if the target object doesn't accept text/**
     * Adds the content of #PCDATA sections to an element.
     *
     * @param project The project containing the target.
     *                Must not be <code>null</code>.
     * @param target  The target object to be configured.
     *                Must not be <code>null</code>.
     * @param text    Text to add to the target.
     *                May be <code>null</code>, in which case this
     *                method call is a no-op.
     *
     * @exception BuildException if the target object doesn't accept text
     */
    public static void addText(Project project, Object target, String text)
        throws BuildException {

        if (text == null) {
            return;
        }
        if (target instanceof TypeAdapter) {
            target = ((TypeAdapter) target).getProxy();
        }
        IntrospectionHelper.getHelper(project, target.getClass()).addText(project, target, text);
    }

    Stores a configured child element within its parent object.
Params: project – Project containing the objects.
               May be null.
parent –  Parent object to add child to.
               Must not be null.
child –   Child object to store in parent.
               Should not be null.
tag –     Name of element which generated the child.
               May be null, in which case
               the child is not stored./**
     * Stores a configured child element within its parent object.
     *
     * @param project Project containing the objects.
     *                May be <code>null</code>.
     * @param parent  Parent object to add child to.
     *                Must not be <code>null</code>.
     * @param child   Child object to store in parent.
     *                Should not be <code>null</code>.
     * @param tag     Name of element which generated the child.
     *                May be <code>null</code>, in which case
     *                the child is not stored.
     */
    public static void storeChild(Project project, Object parent, Object child, String tag) {
        IntrospectionHelper ih = IntrospectionHelper.getHelper(project, parent.getClass());
        ih.storeElement(project, parent, child, tag);
    }

    Replaces ${xxx} style constructions in the given value with
the string value of the corresponding properties.
Params: project – The project containing the properties to replace.
               Must not be null.
value – The string to be scanned for property references.
             May be null.
Throws: BuildException – if the string contains an opening
                          ${ without a closing
                          }
Returns: the original string with the properties replaced, or
        null if the original string is null.
Deprecated: since 1.6.x.
            Use project.replaceProperties().
Since: 1.5/**
     * Replaces <code>${xxx}</code> style constructions in the given value with
     * the string value of the corresponding properties.
     *
     * @param project The project containing the properties to replace.
     *                Must not be <code>null</code>.
     *
     * @param value The string to be scanned for property references.
     *              May be <code>null</code>.
     *
     * @exception BuildException if the string contains an opening
     *                           <code>${</code> without a closing
     *                           <code>}</code>
     * @return the original string with the properties replaced, or
     *         <code>null</code> if the original string is <code>null</code>.
     *
     * @deprecated since 1.6.x.
     *             Use project.replaceProperties().
     * @since 1.5
     */
    @Deprecated
     public static String replaceProperties(Project project, String value) throws BuildException {
        // needed since project properties are not accessible
         return project.replaceProperties(value);
     }

    Replaces ${xxx} style constructions in the given value
with the string value of the corresponding data types.
Params: project – The container project. This is used solely for
               logging purposes. Must not be null.
value – The string to be scanned for property references.
             May be null, in which case this
             method returns immediately with no effect.
keys –  Mapping (String to Object) of property names to their
             values. Must not be null.
Throws: BuildException – if the string contains an opening
                          ${ without a closing
                          }
Returns: the original string with the properties replaced, or
        null if the original string is null.
Deprecated: since 1.6.x.
            Use PropertyHelper./**
     * Replaces <code>${xxx}</code> style constructions in the given value
     * with the string value of the corresponding data types.
     *
     * @param project The container project. This is used solely for
     *                logging purposes. Must not be <code>null</code>.
     * @param value The string to be scanned for property references.
     *              May be <code>null</code>, in which case this
     *              method returns immediately with no effect.
     * @param keys  Mapping (String to Object) of property names to their
     *              values. Must not be <code>null</code>.
     *
     * @exception BuildException if the string contains an opening
     *                           <code>${</code> without a closing
     *                           <code>}</code>
     * @return the original string with the properties replaced, or
     *         <code>null</code> if the original string is <code>null</code>.
     * @deprecated since 1.6.x.
     *             Use PropertyHelper.
     */
    @Deprecated
     public static String replaceProperties(Project project, String value, Hashtable<String, Object> keys)
             throws BuildException {
        PropertyHelper ph = PropertyHelper.getPropertyHelper(project);
        return ph.replaceProperties(null, value, keys);
    }

    Parses a string containing ${xxx} style property
references into two lists. The first list is a collection
of text fragments, while the other is a set of string property names.
null entries in the first list indicate a property
reference from the second list.
As of Ant 1.8.0 this method is never invoked by any code
inside of Ant itself.
Params: value –     Text to parse. Must not be null.
fragments – List to add text fragments to.
                 Must not be null.
propertyRefs – List to add property names to.
                    Must not be null.
Throws: BuildException – if the string contains an opening
                          ${ without a closing }
Deprecated: since 1.6.x.
            Use PropertyHelper./**
     * Parses a string containing <code>${xxx}</code> style property
     * references into two lists. The first list is a collection
     * of text fragments, while the other is a set of string property names.
     * <code>null</code> entries in the first list indicate a property
     * reference from the second list.
     *
     * <p>As of Ant 1.8.0 this method is never invoked by any code
     * inside of Ant itself.</p>
     *
     * @param value     Text to parse. Must not be <code>null</code>.
     * @param fragments List to add text fragments to.
     *                  Must not be <code>null</code>.
     * @param propertyRefs List to add property names to.
     *                     Must not be <code>null</code>.
     *
     * @deprecated since 1.6.x.
     *             Use PropertyHelper.
     * @exception BuildException if the string contains an opening
     *                           <code>${</code> without a closing <code>}</code>
     */
    @Deprecated
    public static void parsePropertyString(String value, Vector<String> fragments, Vector<String> propertyRefs)
            throws BuildException {
        PropertyHelper.parsePropertyStringDefault(value, fragments, propertyRefs);
    }

    Map a namespaced {uri,name} to an internal string format.
For BC purposes the names from the ant core uri will be
mapped to "name", other names will be mapped to
uri + ":" + name.
Params: uri –   The namespace URI
name –  The localname
Returns:      The stringified form of the ns name/**
     * Map a namespaced {uri,name} to an internal string format.
     * For BC purposes the names from the ant core uri will be
     * mapped to "name", other names will be mapped to
     * uri + ":" + name.
     * @param uri   The namespace URI
     * @param name  The localname
     * @return      The stringified form of the ns name
     */
    public static String genComponentName(String uri, String name) {
        if (uri == null || uri.isEmpty() || uri.equals(ANT_CORE_URI)) {
            return name;
        }
        return uri + ":" + name;
    }

    extract a uri from a component name
Params: componentName –  The stringified form for {uri, name}
Returns:               The uri or "" if not present/**
     * extract a uri from a component name
     *
     * @param componentName  The stringified form for {uri, name}
     * @return               The uri or "" if not present
     */
    public static String extractUriFromComponentName(String componentName) {
        if (componentName == null) {
            return "";
        }
        int index = componentName.lastIndexOf(':');
        if (index == -1) {
            return "";
        }
        return componentName.substring(0, index);
    }

    extract the element name from a component name
Params: componentName –  The stringified form for {uri, name}
Returns:               The element name of the component/**
     * extract the element name from a component name
     *
     * @param componentName  The stringified form for {uri, name}
     * @return               The element name of the component
     */
    public static String extractNameFromComponentName(String componentName) {
        int index = componentName.lastIndexOf(':');
        if (index == -1) {
            return componentName;
        }
        return componentName.substring(index + 1);
    }

    Convert an attribute namespace to a "component name".
Params: ns – the xml namespace uri.
Returns: the converted value.
Since: Ant 1.9.1/**
     * Convert an attribute namespace to a "component name".
     * @param ns the xml namespace uri.
     * @return the converted value.
     * @since Ant 1.9.1
     */
    public static String nsToComponentName(String ns) {
        return "attribute namespace:" + ns;
    }

    Add location to build exception.
Params: ex – the build exception, if the build exception
          does not include
newLocation – the location of the calling task (may be null)
Returns: a new build exception based in the build exception with
        location set to newLocation. If the original exception
        did not have a location, just return the build exception/**
     * Add location to build exception.
     * @param ex the build exception, if the build exception
     *           does not include
     * @param newLocation the location of the calling task (may be null)
     * @return a new build exception based in the build exception with
     *         location set to newLocation. If the original exception
     *         did not have a location, just return the build exception
     */
    public static BuildException addLocationToBuildException(
            BuildException ex, Location newLocation) {
        if (ex.getLocation() == null || ex.getMessage() == null) {
            return ex;
        }
        String errorMessage
            = String.format("The following error occurred while executing this line:%n%s%s",
                ex.getLocation().toString(), ex.getMessage());
        if (ex instanceof ExitStatusException) {
            int exitStatus = ((ExitStatusException) ex).getStatus();
            if (newLocation == null) {
                return new ExitStatusException(errorMessage, exitStatus);
            }
            return new ExitStatusException(errorMessage, exitStatus, newLocation);
        }
        if (newLocation == null) {
            return new BuildException(errorMessage, ex);
        }
        return new BuildException(errorMessage, ex, newLocation);
    }

    Whether this instance of ProjectHelper can parse an Antlib
descriptor given by the URL and return its content as an
UnknownElement ready to be turned into an Antlib task.
This method should not try to parse the content of the
descriptor, the URL is only given as an argument to allow
subclasses to decide whether they can support a given URL
scheme or not.
Subclasses that return true in this method must also override 
parseAntlibDescriptor.
This implementation returns false.
Params: r – Resource
Returns: boolean
Since: Ant 1.8.0/**
     * Whether this instance of ProjectHelper can parse an Antlib
     * descriptor given by the URL and return its content as an
     * UnknownElement ready to be turned into an Antlib task.
     *
     * <p>This method should not try to parse the content of the
     * descriptor, the URL is only given as an argument to allow
     * subclasses to decide whether they can support a given URL
     * scheme or not.</p>
     *
     * <p>Subclasses that return true in this method must also
     * override {@link #parseAntlibDescriptor
     * parseAntlibDescriptor}.</p>
     *
     * <p>This implementation returns false.</p>
     *
     * @param r Resource
     * @return boolean
     * @since Ant 1.8.0
     */
    public boolean canParseAntlibDescriptor(Resource r) {
        return false;
    }

    Parse the given URL as an antlib descriptor and return the
content as something that can be turned into an Antlib task.
Params: containingProject – Project
source – Resource
Returns: UnknownElement
Since: ant 1.8.0/**
     * Parse the given URL as an antlib descriptor and return the
     * content as something that can be turned into an Antlib task.
     *
     * @param containingProject Project
     * @param source Resource
     * @return UnknownElement
     * @since ant 1.8.0
     */
    public UnknownElement parseAntlibDescriptor(Project containingProject,
                                                Resource source) {
        throw new BuildException("can't parse antlib descriptors");
    }

    Check if the helper supports the kind of file. Some basic check on the
extension's file should be done here.
Params: buildFile – 
           the file expected to be parsed (never null)
Returns: true if the helper supports it
Since: Ant 1.8.0/**
     * Check if the helper supports the kind of file. Some basic check on the
     * extension's file should be done here.
     *
     * @param buildFile
     *            the file expected to be parsed (never <code>null</code>)
     * @return true if the helper supports it
     * @since Ant 1.8.0
     */
    public boolean canParseBuildFile(Resource buildFile) {
        return true;
    }

    The file name of the build script to be parsed if none specified on the command line
Returns: the name of the default file (never null)
Since: Ant 1.8.0/**
     * The file name of the build script to be parsed if none specified on the command line
     *
     * @return the name of the default file (never <code>null</code>)
     * @since Ant 1.8.0
     */
    public String getDefaultBuildFile() {
        return Main.DEFAULT_BUILD_FILENAME;
    }

    Check extensionStack and inject all targets having extensionOf attributes
into extensionPoint.

This method allow you to defer injection and have a powerful control of
extensionPoint wiring.


This should be invoked by each concrete implementation of ProjectHelper
when the root "buildfile" and all imported/included buildfile are loaded.

Params: project – The project containing the target. Must not be
           null.
Throws: BuildException – if OnMissingExtensionPoint.FAIL and
               extensionPoint does not exist
See Also: OnMissingExtensionPoint
Since: 1.9/**
     * Check extensionStack and inject all targets having extensionOf attributes
     * into extensionPoint.
     * <p>
     * This method allow you to defer injection and have a powerful control of
     * extensionPoint wiring.
     * </p>
     * <p>
     * This should be invoked by each concrete implementation of ProjectHelper
     * when the root "buildfile" and all imported/included buildfile are loaded.
     * </p>
     *
     * @param project The project containing the target. Must not be
     *            <code>null</code>.
     * @exception BuildException if OnMissingExtensionPoint.FAIL and
     *                extensionPoint does not exist
     * @see OnMissingExtensionPoint
     * @since 1.9
     */
    public void resolveExtensionOfAttributes(Project project)
            throws BuildException {
        for (String[] extensionInfo : getExtensionStack()) {
            String extPointName = extensionInfo[0];
            String targetName = extensionInfo[1];
            OnMissingExtensionPoint missingBehaviour = OnMissingExtensionPoint.valueOf(extensionInfo[2]);
            // if the file has been included or imported, it may have a prefix
            // we should consider when trying to resolve the target it is
            // extending
            String prefixAndSep = extensionInfo.length > 3 ? extensionInfo[3] : null;

            // find the target we're extending
            Hashtable<String, Target> projectTargets = project.getTargets();
            Target extPoint = null;
            if (prefixAndSep == null) {
                // no prefix - not from an imported/included build file
                extPoint = projectTargets.get(extPointName);
            } else {
                // we have a prefix, which means we came from an include/import

                // FIXME: here we handle no particular level of include. We try
                // the fully prefixed name, and then the non-prefixed name. But
                // there might be intermediate project in the import stack,
                // which prefix should be tested before testing the non-prefix
                // root name.

                extPoint = projectTargets.get(prefixAndSep + extPointName);
                if (extPoint == null) {
                    extPoint = projectTargets.get(extPointName);
                }
            }

            // make sure we found a point to extend on
            if (extPoint == null) {
                String message = "can't add target " + targetName
                        + " to extension-point " + extPointName
                        + " because the extension-point is unknown.";
                if (missingBehaviour == OnMissingExtensionPoint.FAIL) {
                    throw new BuildException(message);
                } else if (missingBehaviour == OnMissingExtensionPoint.WARN) {
                    Target t = projectTargets.get(targetName);
                    project.log(t, "Warning: " + message, Project.MSG_WARN);
                }
            } else {
                if (!(extPoint instanceof ExtensionPoint)) {
                    throw new BuildException("referenced target " + extPointName
                            + " is not an extension-point");
                }
                extPoint.addDependency(targetName);
            }
        }
    }
}
Params:	project – The project to configure. Must not be `null`. buildFile – A build file giving the project's configuration. Must not be `null`.
Throws:	BuildException – if the configuration is invalid or cannot be read
Params:	project – The project for the resulting ProjectHelper to configure. Must not be `null`. source – The source for XML configuration. A helper must support at least File, for backward compatibility. Helpers may support URL, InputStream, etc or specialized types.
Throws:	BuildException – if the configuration is invalid or cannot be read
Since:	Ant1.5
See Also:	ProjectHelperRepository.getHelpers()
Returns:	an project helper, never `null`
Deprecated:	since 1.6.x. Use LoaderUtils.getContextClassLoader()
Returns:	the current context class loader, or `null` if the context class loader is unavailable.
Params:	target – The target object to be configured. Must not be `null`. attrs – A list of attributes to configure within the target. Must not be `null`. project – The project containing the target. Must not be `null`.
Throws:	BuildException – if any of the attributes can't be handled by the target
Deprecated:	since 1.6.x. Use IntrospectionHelper for each property.
Params:	project – The project containing the target. Must not be `null`. target – The target object to be configured. Must not be `null`. buf – A character array of the text within the element. Will not be `null`. start – The start element in the array. count – The number of characters to read from the array.
Throws:	BuildException – if the target object doesn't accept text
Params:	project – The project containing the properties to replace. Must not be `null`. value – The string to be scanned for property references. May be `null`.
Throws:	BuildException – if the string contains an opening `${` without a closing `}`
Returns:	the original string with the properties replaced, or `null` if the original string is `null`.
Deprecated:	since 1.6.x. Use project.replaceProperties().
Since:	1.5
Params:	project – The container project. This is used solely for logging purposes. Must not be `null`. value – The string to be scanned for property references. May be `null`, in which case this method returns immediately with no effect. keys – Mapping (String to Object) of property names to their values. Must not be `null`.
Throws:	BuildException – if the string contains an opening `${` without a closing `}`
Returns:	the original string with the properties replaced, or `null` if the original string is `null`.
Deprecated:	since 1.6.x. Use PropertyHelper.
Params:	value – Text to parse. Must not be `null`. fragments – List to add text fragments to. Must not be `null`. propertyRefs – List to add property names to. Must not be `null`.
Throws:	BuildException – if the string contains an opening `${` without a closing `}`
Deprecated:	since 1.6.x. Use PropertyHelper.
Params:	uri – The namespace URI name – The localname
Returns:	The stringified form of the ns name
Params:	componentName – The stringified form for {uri, name}
Returns:	The uri or "" if not present
Params:	ns – the xml namespace uri.
Returns:	the converted value.
Since:	Ant 1.9.1
Params:	ex – the build exception, if the build exception does not include newLocation – the location of the calling task (may be null)
Returns:	a new build exception based in the build exception with location set to newLocation. If the original exception did not have a location, just return the build exception
Params:	containingProject – Project source – Resource
Returns:	UnknownElement
Since:	ant 1.8.0
Params:	buildFile – the file expected to be parsed (never `null`)
Returns:	true if the helper supports it
Since:	Ant 1.8.0
Returns:	the name of the default file (never `null`)
Since:	Ant 1.8.0
/

org.apache.ant/ ant/ 1.10.7/ org/apache/tools/ant/ProjectHelper.java
