org.apache.commons.text.lookup.InterpolatorStringLookup Maven / Gradle / Ivy
/*
* 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.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.Map.Entry;
/**
* Proxies other {@link StringLookup}s using a keys within ${} markers using the format "${StringLookup:Key}".
*
* Uses the {@link StringLookupFactory default lookups}.
*
*/
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;
/**
* Creates an instance using only lookups that work without initial properties and are stateless.
*
* Uses the {@link StringLookupFactory default lookups}.
*
*/
InterpolatorStringLookup() {
this((Map) null);
}
/**
* Creates 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(MapStringLookup.on(defaultMap == null ? new HashMap() : defaultMap));
}
/**
* Creates an instance with the given lookup.
*
* @param defaultStringLookup
* the default lookup.
*/
InterpolatorStringLookup(final StringLookup defaultStringLookup) {
this(new HashMap<>(), defaultStringLookup, true);
}
/**
* Creates 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) {
super();
this.defaultStringLookup = defaultStringLookup;
this.stringLookupMap = new HashMap<>(stringLookupMap.size());
for (final Entry entry : stringLookupMap.entrySet()) {
this.stringLookupMap.put(entry.getKey().toLowerCase(Locale.ROOT), entry.getValue());
}
if (addDefaultLookups) {
StringLookupFactory.INSTANCE.addDefaultStringLookups(this.stringLookupMap);
}
}
/**
* 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 var
* 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 var) {
if (var == null) {
return null;
}
final int prefixPos = var.indexOf(PREFIX_SEPARATOR);
if (prefixPos >= 0) {
final String prefix = var.substring(0, prefixPos).toLowerCase(Locale.ROOT);
final String name = var.substring(prefixPos + 1);
final StringLookup lookup = stringLookupMap.get(prefix);
String value = null;
if (lookup != null) {
value = lookup.lookup(name);
}
if (value != null) {
return value;
}
var = var.substring(prefixPos + 1);
}
if (defaultStringLookup != null) {
return defaultStringLookup.lookup(var);
}
return null;
}
@Override
public String toString() {
return getClass().getName() + " [stringLookupMap=" + stringLookupMap + ", defaultStringLookup="
+ defaultStringLookup + "]";
}
}