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 static org.apache.juneau.commons.utils.AssertionUtils.*;
020
021import java.util.regex.*;
022
023import org.apache.juneau.svl.*;
024
025/**
026 * A transformational variable resolver that returns character count or list count (using given delimiter).
027 *
028 * <p>
029 * The format for this var is one of the following:
030 * <ul>
031 *    <li><js>"$LN{arg}"</js>
032 *    <li><js>"$LN{arg,delimiter}"</js>
033 * </ul>
034 *
035 * <h5 class='section'>Example:</h5>
036 * <p class='bjava'>
037 *    <jc>// Create a variable resolver that resolves system properties and $SW vars.</jc>
038 *    VarResolver <jv>varResolver</jv> = VarResolver.<jsm>create</jsm>().vars(LenVar.<jk>class</jk>, SystemPropertiesVar.<jk>class</jk>).build();
039 *
040 *    <jc>// Use it!</jc>
041 *    System.<jsf>out</jsf>.println(<jv>varResolver</jv>.resolve(<js>"Parts = $LN{$P{os.version},.} Chars = $LN{$P{os.version}}"</js>));
042 * </p>
043 *
044 * <p>
045 * Since this is a {@link MultipartVar}, any variables contained in the result will be recursively resolved.
046 * <br>Likewise, if the arguments contain any variables, those will be resolved before they are passed to this var.
047 *
048 * <h5 class='section'>See Also:</h5><ul>
049 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/SimpleVariableLanguageBasics">Simple Variable Language Basics</a>
050 * </ul>
051 */
052public class LenVar extends MultipartVar {
053
054   /** The name of this variable. */
055   public static final String NAME = "LN";
056
057   /**
058    * Constructor.
059    */
060   public LenVar() {
061      super(NAME);
062   }
063
064   @Override /* Overridden from MultipartVar */
065   public String resolve(VarResolverSession session, String[] args) {
066      assertArg(args.length <= 2, "Invalid number of arguments passed to $LN var.  Must have 1 or 2 arguments.");
067
068      int len = 0;
069      String stringArg = args[0];
070      if (args.length == 1)
071         len = stringArg.length();
072      else if (args.length == 2) {
073         //delimiter is given
074         String delimiter = Pattern.quote(args[1]);
075         len = stringArg.trim().split(delimiter).length;
076      }
077      return String.valueOf(len);
078   }
079}