001// ***************************************************************************************************************************
002// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
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004// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance            *
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006// *                                                                                                                         *
007// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
008// *                                                                                                                         *
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011// * specific language governing permissions and limitations under the License.                                              *
012// ***************************************************************************************************************************
013package org.apache.juneau.config.mod;
014
015import java.util.function.*;
016
017/**
018 * Specifies an entry modifier that is used to encode during write and decode during read of config entries.
019 */
020public class Mod {
021
022   //-----------------------------------------------------------------------------------------------------------------
023   // Static
024   //-----------------------------------------------------------------------------------------------------------------
025
026   /** A no-op modifier. */
027   public static final Mod NO_OP = new Mod(' ', x -> x, x -> x, x -> true);
028
029   //-----------------------------------------------------------------------------------------------------------------
030   // Instance
031   //-----------------------------------------------------------------------------------------------------------------
032
033   private final char id;
034   private final Function<String,String> removeFunction, applyFunction;
035   private final Function<String,Boolean> detectFunction;
036
037   /**
038    * Constructor.
039    *
040    * @param id The character identifier.
041    * @param applyFunction
042    *    The function to apply when writing an entry.
043    *    Can be <jk>null</jk> if you override the {@link #apply(String)} method.
044    * @param removeFunction
045    *    The function to apply when reading an entry.
046    *    Can be <jk>null</jk> if you override the {@link #remove(String)} method.
047    * @param detectFunction
048    *    The function to apply to detect whether the modification has been made.
049    *    Can be <jk>null</jk> if you override the {@link #isApplied(String)} method.
050    */
051   public Mod(char id, Function<String,String> applyFunction, Function<String,String> removeFunction, Function<String,Boolean> detectFunction) {
052      this.id = id;
053      this.applyFunction = applyFunction;
054      this.removeFunction = removeFunction;
055      this.detectFunction = detectFunction;
056   }
057
058   /**
059    * Returns the modifier identifier character.
060    *
061    * @return The modifier identifier character.
062    */
063   public char getId() {
064      return id;
065   }
066
067   /**
068    * Detects whether this modification has been applied.
069    *
070    * @param value The entry value being tested.  Will never be <jk>null</jk>.
071    * @return <jk>true</jk> if the modification has been made to the entry.
072    */
073   public boolean isApplied(String value) {
074      return detectFunction.apply(value);
075   }
076
077   /**
078    * Applies this modification to the specified entry value.
079    *
080    * <p>
081    * Will only be called if {@link #isApplied(String)} returns <jk>false</jk>.
082    *
083    * @param value The entry value being written.  Will never be <jk>null</jk>.
084    * @return The modified value.
085    */
086   public String apply(String value) {
087      return applyFunction.apply(value);
088   }
089
090   /**
091    * Removes this modification to the specified entry value.
092    *
093    * <p>
094    * Will only be called if {@link #isApplied(String)} returns <jk>true</jk>.
095    *
096    * @param value The entry value being read.  Will never be <jk>null</jk>.
097    * @return The unmodified value.
098    */
099   public String remove(String value) {
100      return removeFunction.apply(value);
101   }
102
103   /**
104    * Applies this modification to the specified entry value if it isn't already applied.
105    *
106    * @param value The entry value being written.  Will never be <jk>null</jk>.
107    * @return The modified value.
108    */
109   public final String doApply(String value) {
110      return isApplied(value) ? value : apply(value);
111   }
112
113   /**
114    * Removes this modification from the specified entry value if it is applied.
115    *
116    * @param value The entry value being written.  Will never be <jk>null</jk>.
117    * @return The modified value.
118    */
119   public final String doRemove(String value) {
120      return isApplied(value) ? remove(value) : value;
121   }
122}