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Apache Commons Text is a library focused on algorithms working on strings.
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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.Objects;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import org.apache.commons.text.StringSubstitutor;
/**
* Executes the script with the given engine name.
*
* Execute the script with the engine name in the format "EngineName:Script".
*
*
* For example: {@code "javascript:3 + 4"}.
*
*
* Using a {@link StringSubstitutor}:
*
*
*
* StringSubstitutor.createInterpolator().replace("${script:javascript:3 + 4}"));
*
*
* @since 1.5
*/
final class ScriptStringLookup extends AbstractStringLookup {
/**
* Defines the singleton for this class.
*/
static final ScriptStringLookup INSTANCE = new ScriptStringLookup();
/**
* No need to build instances for now.
*/
private ScriptStringLookup() {
// empty
}
/**
* Execute the script with the engine name in the format "EngineName:Script". Extra colons will be ignored.
*
* For example: {@code "javascript:3 + 4"}.
*
*
* @param key the engine:script to execute, may be null
* @return The value returned by the execution.
*/
@Override
public String lookup(final String key) {
if (key == null) {
return null;
}
final String[] keys = key.split(SPLIT_STR, 2);
final int keyLen = keys.length;
if (keyLen != 2) {
throw IllegalArgumentExceptions.format("Bad script key format [%s]; expected format is EngineName:Script.",
key);
}
final String engineName = keys[0];
final String script = keys[1];
try {
final ScriptEngine scriptEngine = new ScriptEngineManager().getEngineByName(engineName);
if (scriptEngine == null) {
throw new IllegalArgumentException("No script engine named " + engineName);
}
return Objects.toString(scriptEngine.eval(script), null);
} catch (final Exception e) {
throw IllegalArgumentExceptions.format(e, "Error in script engine [%s] evaluating script [%s].", engineName,
script);
}
}
}
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