001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.juneau.svl.vars;
018
019import java.util.regex.*;
020
021import org.apache.juneau.common.utils.*;
022import org.apache.juneau.svl.*;
023
024/**
025 * A transformational variable resolver that returns character count or list count (using given delimiter).
026 *
027 * <p>
028 * The format for this var is one of the following:
029 * <ul>
030 *    <li><js>"$LN{arg}"</js>
031 *    <li><js>"$LN{arg,delimiter}"</js>
032 * </ul>
033 *
034 * <h5 class='section'>Example:</h5>
035 * <p class='bjava'>
036 *    <jc>// Create a variable resolver that resolves system properties and $SW vars.</jc>
037 *    VarResolver <jv>varResolver</jv> = VarResolver.<jsm>create</jsm>().vars(LenVar.<jk>class</jk>, SystemPropertiesVar.<jk>class</jk>).build();
038 *
039 *    <jc>// Use it!</jc>
040 *    System.<jsf>out</jsf>.println(<jv>varResolver</jv>.resolve(<js>"Parts = $LN{$P{os.version},.} Chars = $LN{$P{os.version}}"</js>));
041 * </p>
042 *
043 * <p>
044 * Since this is a {@link MultipartVar}, any variables contained in the result will be recursively resolved.
045 * <br>Likewise, if the arguments contain any variables, those will be resolved before they are passed to this var.
046 *
047 * <h5 class='section'>See Also:</h5><ul>
048 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/SimpleVariableLanguageBasics">Simple Variable Language Basics</a>
049 * </ul>
050 */
051public class LenVar extends MultipartVar {
052
053   /** The name of this variable. */
054   public static final String NAME = "LN";
055
056   /**
057    * Constructor.
058    */
059   public LenVar() {
060      super(NAME);
061   }
062
063   @Override /* MultipartVar */
064   public String resolve(VarResolverSession session, String[] args) {
065      Utils.assertArg(args.length <= 2, "Invalid number of arguments passed to $LN var.  Must have 1 or 2 arguments.");
066
067      int len = 0;
068      String stringArg = args[0];
069      if (args.length == 1)
070         len = stringArg.length();
071      else if (args.length == 2) {
072         //delimiter is given
073         String delimiter = Pattern.quote(args[1]);
074         len = stringArg.trim().split(delimiter).length;
075      }
076      return String.valueOf(len);
077   }
078}