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package org.apache.juneau.svl.vars;

import static org.apache.juneau.assertions.Assertions.*;
import org.apache.juneau.svl.*;

/**
 * A transformational variable resolver that replaces matched patterns with given characters.
 *
 * <p>
 * The format for this var is:
 * <ul>
 * 	<li><js>"$PR{stringArg,pattern,replace}"</js>
 * </ul>
 *
 * <p>
 * The pattern can be any string optionally containing <js>'*'</js> or <js>'?'</js> representing any or one character
 * respectively.
 *
 * The replace can contain matched regex sub classes like \$1, \$2 ..
 *
 * <h5 class='section'>Example:</h5>
 * <p class='bjava'>
 * 	<jc>// Create a variable resolver that resolves system properties and $SW vars.</jc>
 * 	VarResolver <jv>varResolver</jv> = VarResolver.<jsm>create</jsm>().vars(PatternReplaceVar.<jk>class</jk>, SystemPropertiesVar.<jk>class</jk>).build();
 *
 * 	<jc>// Use it!</jc>
 * 	System.<jsf>out</jsf>.println(<jv>varResolver</jv>.resolve(<js>"Java version=$PR{$S{java.version}, (_([0-9]+)), \\ build=\\$2}"</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 jm.SimpleVariableLanguage}
 * 	<li class='extlink'>{@source}
 * </ul>
 */
public class PatternReplaceVar extends MultipartVar {

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

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

	@Override /* MultipartVar */
	public String resolve(VarResolverSession session, String[] args) {
		assertArg(args.length >= 3, "Invalid number of arguments passed to $PR var.  Must have 3 or more arguments.");

		String stringArg = args[0];
		String pattern = args[1];
		String replace = args[2];

		pattern = pattern.replace("*", ".*").replace("?", ".");
		return stringArg.replaceAll(pattern, replace);
	}
}