StreamToIteratorWhile.java

/*******************************************************************************
 * Copyright (c) 2026 Carsten Hammer.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     Carsten Hammer
 *******************************************************************************/
package org.sandbox.jdt.internal.corext.fix.helper;

import java.util.Set;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.jdt.core.dom.ASTNode;
import org.eclipse.jdt.core.dom.CompilationUnit;
import org.eclipse.jdt.internal.corext.fix.CompilationUnitRewriteOperationsFixCore.CompilationUnitRewriteOperation;
import org.eclipse.jdt.internal.corext.refactoring.structure.CompilationUnitRewrite;
import org.eclipse.text.edits.TextEditGroup;
import org.sandbox.functional.core.model.LoopModel;
import org.sandbox.jdt.internal.common.ReferenceHolder;
import org.sandbox.jdt.internal.corext.fix.UseFunctionalCallFixCore;

/**
 * Transformer for converting Stream forEach expressions to iterator-based while-loops.
 * 
 * <p>Transformation: {@code collection.forEach(item -> ...)} → {@code Iterator<T> it = c.iterator(); while (it.hasNext()) { T item = it.next(); ... }}</p>
 * 
 * <p>Uses the ULR pipeline: {@code LoopModelBuilder → LoopModel → ASTIteratorWhileRenderer}.</p>
 * 
 * @see LoopModel
 * @see ASTIteratorWhileRenderer
 * @see <a href="https://github.com/carstenartur/sandbox/issues/453">Issue #453</a>
 * @see <a href="https://github.com/carstenartur/sandbox/issues/549">Issue #549</a>
 */
public class StreamToIteratorWhile extends AbstractFunctionalCall<ASTNode> {

	@Override
	public void find(UseFunctionalCallFixCore fixcore, CompilationUnit compilationUnit,
			Set<CompilationUnitRewriteOperation> operations, Set<ASTNode> nodesprocessed) {
		ExpressionHelper.findForEachInvocations(fixcore, compilationUnit, operations, nodesprocessed);
	}

	@Override
	public void rewrite(UseFunctionalCallFixCore useExplicitEncodingFixCore, ASTNode visited,
			CompilationUnitRewrite cuRewrite, TextEditGroup group, ReferenceHolder<ASTNode, Object> data)
			throws CoreException {
		ExpressionHelper.ForEachRewriteInfo info = ExpressionHelper.extractForEachRewriteInfo(visited, cuRewrite.getAST());
		if (info == null) {
			return;
		}
		
		ASTIteratorWhileRenderer renderer = new ASTIteratorWhileRenderer(cuRewrite.getAST(), cuRewrite.getASTRewrite());
		renderer.renderWithBodyStatements(info.model(), info.forEachStatement(), info.bodyStatements(), group);
		
		// Add Iterator import
		cuRewrite.getImportRewrite().addImport("java.util.Iterator"); //$NON-NLS-1$
	}

	@Override
	public String getPreview(boolean afterRefactoring) {
		if (afterRefactoring) {
			return """
					Iterator<String> it = items.iterator();
					while (it.hasNext()) {
						String item = it.next();
						System.out.println(item);
					}
					""";
		}
		return """
				items.forEach(item -> System.out.println(item));
				""";
	}
}