juneau-core/juneau-marshall/src/main/java/org/apache/juneau/svl/vars/PatternMatchVar.java

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package org.apache.juneau.svl.vars;

import static org.apache.juneau.assertions.Assertions.*;
import java.util.regex.*;

import org.apache.juneau.svl.*;

/**
 * A logical variable resolver that resolves to <js>"true</js> if a pattern matches.
 *
 * <p>
 * The format for this var is one of the following:
 * <ul>
 * 	<li><js>"$PM{stringArg, pattern}"</js>
 * 	<li>...
 * </ul>
 *
 * <p>
 * The pattern can be any string optionally containing <js>'*'</js> or <js>'?'</js> representing any or one character
 * respectively.
 *
 * <h5 class='section'>Example:</h5>
 * <p class='bcode w800'>
 * 	<jc>// Create a variable resolver that resolves system properties and $SW vars.</jc>
 * 	VarResolver r = VarResolver.<jsm>create</jsm>().vars(PatternMatchVar.<jk>class</jk>, SystemPropertiesVar.<jk>class</jk>).build();
 *
 * 	<jc>// Use it!</jc>
 * 	System.<jsf>out</jsf>.println(r.resolve(<js>"Running on Windows?  $PM{$P{os.name},*win*}!"</js>));
 * </p>
 *
 * <p>
 * Since this is a {@link MultipartVar}, any variables contained in the result will be recursively resolved.
 * <br>Likewise, if the arguments contain any variables, those will be resolved before they are passed to this var.
 *
 * <ul class='seealso'>
 * 	<li class='link'>{@doc SvlVariables}
 * </ul>
 */
public class PatternMatchVar extends MultipartVar {

	/** The name of this variable. */
	public static final String NAME = "PM";

	/**
	 * Constructor.
	 */
	public PatternMatchVar() {
		super(NAME);
	}

	@Override /* MultipartVar */
	public String resolve(VarResolverSession session, String[] args) {
		assertArg(args.length >= 2, "Invalid number of arguments passed to $PM var.  Must have 2 or more arguments.");

		String stringArg = args[0];
		String pattern = args[1];
		Pattern p = Pattern.compile(pattern.replace("*", ".*").replace("?", "."));
		return String.valueOf(p.matcher(stringArg).matches());
	}
}