nz.net.ultraq.thymeleaf.layoutdialect.models.VariableDeclarationMerger Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of thymeleaf-layout-dialect Show documentation
Thymeleaf Layout Dialect rewritten in java.
The newest version!
/*
 * Copyright 2016, Emanuel Rabina (http://www.ultraq.net.nz/)
 *
 * 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.
 */
package nz.net.ultraq.thymeleaf.layoutdialect.models;

import org.thymeleaf.context.IExpressionContext;
import org.thymeleaf.util.StringUtils;

import java.util.ArrayList;
import java.util.List;
import java.util.Objects;

/**
 * Merges variable declarations in a {@code th:with} attribute processor, taking
 * the declarations in the target and combining them with the declarations in
 * the source, overriding any same-named declarations in the target.
 *
 * @author zhanhb
 * @author Emanuel Rabina
 */
public class VariableDeclarationMerger {

	private final IExpressionContext context;

	/**
	 * Constructor, sets the processing context for the merger.
	 *
	 * @param context
	 */
	public VariableDeclarationMerger(IExpressionContext context) {
		this.context = context;
	}

	/**
	 * Merge {@code th:with} attributes so that names from the source value
	 * overwrite the same names in the target value.
	 *
	 * @param target
	 * @param source
	 * @return
	 */
	public String merge(String target, String source) {
		if (StringUtils.isEmpty(target)) {
			return source;
		}
		if (StringUtils.isEmpty(source)) {
			return target;
		}
		VariableDeclarationParser declarationParser = new VariableDeclarationParser(context);
		List targetDeclarations = declarationParser.parse(target);
		List sourceDeclarations = declarationParser.parse(source);

		List newDeclarations = new ArrayList<>(targetDeclarations.size() + sourceDeclarations.size());
		for (VariableDeclaration targetDeclaration : targetDeclarations) {
			VariableDeclaration override = null;
			String name = targetDeclaration.getName();
			for (VariableDeclaration sourceDeclaration : sourceDeclarations) {
				if (Objects.equals(name, sourceDeclaration.getName())) {
					override = sourceDeclaration;
					break;
				}
			}
			if (override != null) {
				sourceDeclarations.remove(override);
				newDeclarations.add(override);
			} else {
				newDeclarations.add(targetDeclaration);
			}
		}

		newDeclarations.addAll(sourceDeclarations);

		StringBuilder buffer = new StringBuilder(source.length() + target.length());
		boolean first = true;

		for (Object value : newDeclarations) {
			if (first) {
				first = false;
			} else {
				buffer.append(',');
			}
			buffer.append(value);
		}
		return buffer.toString();
	}

	public final IExpressionContext getContext() {
		return this.context;
	}

}