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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache license, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the license for the specific language governing permissions and
 * limitations under the license.
 */
package org.apache.commons.text.lookup;

import java.util.Collections;
import java.util.Map;
import java.util.Map.Entry;
import java.util.stream.Collectors;

/**
 * Proxies other {@link StringLookup}s using a keys within ${} markers using the format "${StringLookup:Key}".
 * 

* Uses the {@link StringLookupFactory default lookups}. *

*/ final class InterpolatorStringLookup extends AbstractStringLookup { /** * Defines the singleton for this class. * * @since 1.6 */ static final AbstractStringLookup INSTANCE = new InterpolatorStringLookup(); /** Constant for the prefix separator. */ private static final char PREFIX_SEPARATOR = ':'; /** The default string lookup. */ private final StringLookup defaultStringLookup; /** The map of String lookups keyed by prefix. */ private final Map stringLookupMap; /** * Constructs an instance using only lookups that work without initial properties and are stateless. *

* Uses the {@link StringLookupFactory default lookups}. *

*/ InterpolatorStringLookup() { this((Map) null); } /** * Constructs a fully customized instance. * * @param stringLookupMap the map of string lookups. * @param defaultStringLookup the default string lookup. * @param addDefaultLookups whether the default lookups should be used. */ InterpolatorStringLookup(final Map stringLookupMap, final StringLookup defaultStringLookup, final boolean addDefaultLookups) { this.defaultStringLookup = defaultStringLookup; this.stringLookupMap = stringLookupMap.entrySet().stream().collect(Collectors.toMap(e -> StringLookupFactory.toKey(e.getKey()), Entry::getValue)); if (addDefaultLookups) { StringLookupFactory.INSTANCE.addDefaultStringLookups(this.stringLookupMap); } } /** * Constructs an instance using only lookups that work without initial properties and are stateless. *

* Uses the {@link StringLookupFactory default lookups}. *

* * @param the map's value type. * @param defaultMap the default map for string lookups. */ InterpolatorStringLookup(final Map defaultMap) { this(StringLookupFactory.INSTANCE.mapStringLookup(defaultMap)); } /** * Constructs an instance with the given lookup. * * @param defaultStringLookup the default lookup. */ InterpolatorStringLookup(final StringLookup defaultStringLookup) { this(Collections.emptyMap(), defaultStringLookup, true); } /** * Gets the lookup map. * * @return The lookup map. */ public Map getStringLookupMap() { return stringLookupMap; } /** * Resolves the specified variable. This implementation will try to extract a variable prefix from the given * variable name (the first colon (':') is used as prefix separator). It then passes the name of the variable with * the prefix stripped to the lookup object registered for this prefix. If no prefix can be found or if the * associated lookup object cannot resolve this variable, the default lookup object will be used. * * @param key the name of the variable whose value is to be looked up * @return The value of this variable or null if it cannot be resolved */ @Override public String lookup(String key) { if (key == null) { return null; } final int prefixPos = key.indexOf(PREFIX_SEPARATOR); if (prefixPos >= 0) { final String prefix = StringLookupFactory.toKey(key.substring(0, prefixPos)); final String name = key.substring(prefixPos + 1); final StringLookup lookup = stringLookupMap.get(prefix); String value = null; if (lookup != null) { value = lookup.lookup(name); } if (value != null) { return value; } key = key.substring(prefixPos + 1); } if (defaultStringLookup != null) { return defaultStringLookup.lookup(key); } return null; } @Override public String toString() { return super.toString() + " [stringLookupMap=" + stringLookupMap + ", defaultStringLookup=" + defaultStringLookup + "]"; } }




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