public Object getValue(String expression) {
            Object value = valueSource.getValue(expression);

            if (value != null && expression.startsWith(bannedPrefix)) {
                String msg = "The expression ${" + expression + "} is deprecated.";
                if (newPrefix != null && !newPrefix.isEmpty()) {
                    msg += " Please use ${" + newPrefix + expression.substring(bannedPrefix.length()) + "} instead.";

        if (basedir != null) {
            interpolator.addValueSource(new AbstractValueSource(false) {
                @Override
                public Object getValue(String expression) {
                    if ("basedir".equals(expression) || "project.basedir".equals(expression)) {
                        return basedir.toAbsolutePath().toString();
                    }
                    return null;
                }
            });

import org.codehaus.plexus.component.configurator.ConfigurationListener;
import org.codehaus.plexus.component.configurator.expression.ExpressionEvaluationException;
import org.codehaus.plexus.component.configurator.expression.ExpressionEvaluator;
import org.codehaus.plexus.component.repository.ComponentDescriptor;
import org.codehaus.plexus.component.repository.exception.ComponentLifecycleException;

permissions and limitations * under the License. */ import org.apache.maven.plugin.AbstractMojo; /** * Does nothing. * * @goal java * @phase generate-sources * * @author Benjamin Bentmann */ public class AMojo extends AbstractMojo { /** @parameter expression="${version}" default-value="1.0" */ private String version; /** @parameter */ private String[] models; public void execute() { } } src/main/java/org/apache/maven/plugins/coreit/BMojo.java src/main/java/org/apache/maven/plugins/coreit/BMojo.java...

import org.apache.maven.project.MavenProject;
import org.codehaus.plexus.MutablePlexusContainer;
import org.codehaus.plexus.PlexusContainer;
import org.codehaus.plexus.component.configurator.expression.ExpressionEvaluator;
import org.codehaus.plexus.configuration.DefaultPlexusConfiguration;
import org.codehaus.plexus.util.Os;
import org.eclipse.aether.DefaultRepositorySystemSession;
import org.eclipse.aether.RepositorySystem;

                    filters.add(new HighestVersionFilter(num));
                } else if ("l".equals(expression)) {
                    filters.add(new LowestVersionFilter());
                } else if (expression.startsWith("l(") && expression.endsWith(")")) {
                    int num = Integer.parseInt(expression.substring(2, expression.length() - 1));

          </description>
        </field>
        <field>
          <name>expression</name>
          <version>2.0.0+</version>
          <type>String</type>
          <description>Parameter expression, to let user override default value with a user property, system property or project property.</description>
        </field>
        <field>

        assertEquals("maven-it-plugin-expression", pom.getValue("build/plugins[2]/artifactId"));
        assertEquals("maven-it-plugin-configuration", pom.getValue("build/plugins[3]/artifactId"));

        assertEquals("maven-it-plugin-log-file", pom.getValue("reporting/plugins[1]/artifactId"));
        assertEquals("maven-it-plugin-expression", pom.getValue("reporting/plugins[2]/artifactId"));

    public static final List<String> VALID_MODEL_VERSIONS =
            Collections.unmodifiableList(Arrays.asList("4.0.0", "4.1.0"));

    private static final Pattern EXPRESSION_NAME_PATTERN = Pattern.compile("\\$\\{(.+?)}");
    private static final Pattern EXPRESSION_PROJECT_NAME_PATTERN = Pattern.compile("\\$\\{(project.+?)}");

    private static final String ILLEGAL_FS_CHARS = "\\/:\"<>|?*";

import org.apache.maven.api.services.ModelProblemCollector;

/**
 * Replaces expressions of the form <code>${token}</code> with their effective values. Effective values are basically
 * calculated from the elements of the model itself and the execution properties from the building request.
 *
 */
public interface ModelInterpolator {

    /**
     * Interpolates expressions in the specified model. Note that implementations are free to either interpolate the