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/*-
* ============LICENSE_START=======================================================
* ONAP - SO
* ================================================================================
* Copyright (C) 2017 AT&T Intellectual Property. All rights reserved.
* ================================================================================
* Licensed 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.
* ============LICENSE_END=========================================================
*/
package org.openecomp.mso.bpmn.core.internal;
import java.util.Optional;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Extracts variable name from expression if entire expression is just
* one variable, for example "${x}".
*
* Ignores all whitespaces, except inside variable name.
*
* Examples:
* "${x}", extracted variable name is "x"
* " ${\t weird_NAME }", extracted variable name is "weird_NAME"
* "${incorrect name}", no extracted name
* "${two}+${two}", no extracted name
*/
public class VariableNameExtractor {
private static final Pattern VARIABLE_NAME_PATTERN = Pattern
.compile("^\\s*\\$\\s*\\{\\s*([a-zA-Z0-9_]+)\\s*\\}\\s*$");
private final String expression;
/**
* Creates new VariableNameExtractor
* @param expression expression to be parsed
*/
public VariableNameExtractor(String expression) {
this.expression = expression;
}
/**
* Extracts variable name from expression given in constructor
* @return Optional of variable name, empty if expression wasn't single variable
*/
public Optional<String> extract() {
Matcher matcher = VARIABLE_NAME_PATTERN.matcher(expression);
if (!matcher.matches()) {
return Optional.empty();
}
return Optional.of(matcher.group(1));
}
}
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