Copyright (c) 2000, 2019 IBM Corporation and others.
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:
    IBM Corporation - initial API and implementation
    Microsoft Corporation - copied to jdt.core.manipulation
/*******************************************************************************
 * Copyright (c) 2000, 2019 IBM Corporation and others.
 *
 * 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:
 *     IBM Corporation - initial API and implementation
 *     Microsoft Corporation - copied to jdt.core.manipulation
 *******************************************************************************/
package org.eclipse.jdt.internal.corext.dom;

import org.eclipse.core.runtime.Assert;

import org.eclipse.jdt.core.dom.ASTNode;
import org.eclipse.jdt.core.dom.ASTVisitor;
import org.eclipse.jdt.core.dom.BodyDeclaration;
import org.eclipse.jdt.core.dom.FieldDeclaration;
import org.eclipse.jdt.core.dom.IVariableBinding;
import org.eclipse.jdt.core.dom.Initializer;
import org.eclipse.jdt.core.dom.MethodDeclaration;
import org.eclipse.jdt.core.dom.SingleVariableDeclaration;
import org.eclipse.jdt.core.dom.VariableDeclarationFragment;


public class LocalVariableIndex extends ASTVisitor {

	private int fTopIndex;

	
Computes the maximum number of local variable declarations in the
given body declaration.
Params:
declaration – the body declaration. Must either be a method
 declaration, or an initializer, or a field declaration.
Returns:
the maximum number of local variables/**
	 * Computes the maximum number of local variable declarations in the
	 * given body declaration.
	 *
	 * @param declaration the body declaration. Must either be a method
	 *  declaration, or an initializer, or a field declaration.
	 * @return the maximum number of local variables
	 */
	public static int perform(BodyDeclaration declaration) {
		Assert.isTrue(declaration != null);
		switch (declaration.getNodeType()) {
			case ASTNode.METHOD_DECLARATION:
			case ASTNode.FIELD_DECLARATION:
			case ASTNode.INITIALIZER:
				return internalPerform(declaration);
			default:
				throw new IllegalArgumentException(declaration.toString());
		}
	}

	private static int internalPerform(BodyDeclaration methodOrInitializer) {
		// we have to find the outermost method/initializer/field declaration since a local or anonymous
		// type can reference final variables from the outer scope.
		BodyDeclaration target= methodOrInitializer;
		ASTNode parent= target.getParent();
		while (parent != null) {
			if (parent instanceof MethodDeclaration || parent instanceof Initializer || parent instanceof FieldDeclaration) {
				target= (BodyDeclaration)parent;
			}
			parent= parent.getParent();
		}

		return doPerform(target);
	}

	private static int doPerform(BodyDeclaration node) {
		LocalVariableIndex counter= new LocalVariableIndex();
		node.accept(counter);
		return counter.fTopIndex;
	}

	@Override
	public boolean visit(SingleVariableDeclaration node) {
		handleVariableBinding(node.resolveBinding());
		return true;
	}

	@Override
	public boolean visit(VariableDeclarationFragment node) {
		handleVariableBinding(node.resolveBinding());
		return true;
	}

	private void handleVariableBinding(IVariableBinding binding) {
		if (binding == null)
			return;
		fTopIndex= Math.max(fTopIndex, binding.getVariableId());
	}
}