Copyright (c) 2000, 2013 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
/*******************************************************************************
 * Copyright (c) 2000, 2013 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
 *******************************************************************************/

package org.eclipse.jdt.core.dom;

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

If statement AST node type.
IfStatement:
   if ( Expression ) Statement [ else Statement]

Since:
2.0
@noinstantiate
This class is not intended to be instantiated by clients./**
 * If statement AST node type.
 * <pre>
 * IfStatement:
 *    <b>if</b> <b>(</b> Expression <b>)</b> Statement [ <b>else</b> Statement]
 * </pre>
 *
 * @since 2.0
 * @noinstantiate This class is not intended to be instantiated by clients.
 */
@SuppressWarnings("rawtypes")
public class IfStatement extends Statement {

	
The "expression" structural property of this node type (child type: Expression). 
Since:
3.0/**
	 * The "expression" structural property of this node type (child type: {@link Expression}).
	 * @since 3.0
	 */
	public static final ChildPropertyDescriptor EXPRESSION_PROPERTY =
		new ChildPropertyDescriptor(IfStatement.class, "expression", Expression.class, MANDATORY, CYCLE_RISK); //$NON-NLS-1$

	
The "thenStatement" structural property of this node type (child type: Statement). 
Since:
3.0/**
	 * The "thenStatement" structural property of this node type (child type: {@link Statement}).
	 * @since 3.0
	 */
	public static final ChildPropertyDescriptor THEN_STATEMENT_PROPERTY =
		new ChildPropertyDescriptor(IfStatement.class, "thenStatement", Statement.class, MANDATORY, CYCLE_RISK); //$NON-NLS-1$

	
The "elseStatement" structural property of this node type (child type: Statement). 
Since:
3.0/**
	 * The "elseStatement" structural property of this node type (child type: {@link Statement}).
	 * @since 3.0
	 */
	public static final ChildPropertyDescriptor ELSE_STATEMENT_PROPERTY =
		new ChildPropertyDescriptor(IfStatement.class, "elseStatement", Statement.class, OPTIONAL, CYCLE_RISK); //$NON-NLS-1$

	
A list of property descriptors (element type: StructuralPropertyDescriptor), or null if uninitialized. /**
	 * A list of property descriptors (element type:
	 * {@link StructuralPropertyDescriptor}),
	 * or null if uninitialized.
	 */
	private static final List PROPERTY_DESCRIPTORS;

	static {
		List properyList = new ArrayList(4);
		createPropertyList(IfStatement.class, properyList);
		addProperty(EXPRESSION_PROPERTY, properyList);
		addProperty(THEN_STATEMENT_PROPERTY, properyList);
		addProperty(ELSE_STATEMENT_PROPERTY, properyList);
		PROPERTY_DESCRIPTORS = reapPropertyList(properyList);
	}

	
Returns a list of structural property descriptors for this node type.
Clients must not modify the result.
Params:
apiLevel – the API level; one of the
AST.JLS* constants
Returns:
a list of property descriptors (element type: StructuralPropertyDescriptor)
Since:
3.0/**
	 * Returns a list of structural property descriptors for this node type.
	 * Clients must not modify the result.
	 *
	 * @param apiLevel the API level; one of the
	 * <code>AST.JLS*</code> constants

	 * @return a list of property descriptors (element type:
	 * {@link StructuralPropertyDescriptor})
	 * @since 3.0
	 */
	public static List propertyDescriptors(int apiLevel) {
		return PROPERTY_DESCRIPTORS;
	}

	
The expression; lazily initialized; defaults to an unspecified, but
legal, expression.
/**
	 * The expression; lazily initialized; defaults to an unspecified, but
	 * legal, expression.
	 */
	private Expression expression = null;

	
The then statement; lazily initialized; defaults to an unspecified, but
legal, statement.
/**
	 * The then statement; lazily initialized; defaults to an unspecified, but
	 * legal, statement.
	 */
	private Statement thenStatement = null;

	
The else statement; null for none; defaults to none.
/**
	 * The else statement; <code>null</code> for none; defaults to none.
	 */
	private Statement optionalElseStatement = null;

	
Creates a new unparented if statement node owned by the given
AST. By default, the expresssion is unspecified,
but legal, the then statement is an empty block, and there is no else
statement.

N.B. This constructor is package-private.

Params:
ast – the AST that is to own this node/**
	 * Creates a new unparented if statement node owned by the given
	 * AST. By default, the expresssion is unspecified,
	 * but legal, the then statement is an empty block, and there is no else
	 * statement.
	 * <p>
	 * N.B. This constructor is package-private.
	 * </p>
	 *
	 * @param ast the AST that is to own this node
	 */
	IfStatement(AST ast) {
		super(ast);
	}

	@Override
	final List internalStructuralPropertiesForType(int apiLevel) {
		return propertyDescriptors(apiLevel);
	}

	@Override
	final ASTNode internalGetSetChildProperty(ChildPropertyDescriptor property, boolean get, ASTNode child) {
		if (property == EXPRESSION_PROPERTY) {
			if (get) {
				return getExpression();
			} else {
				setExpression((Expression) child);
				return null;
			}
		}
		if (property == THEN_STATEMENT_PROPERTY) {
			if (get) {
				return getThenStatement();
			} else {
				setThenStatement((Statement) child);
				return null;
			}
		}
		if (property == ELSE_STATEMENT_PROPERTY) {
			if (get) {
				return getElseStatement();
			} else {
				setElseStatement((Statement) child);
				return null;
			}
		}
		// allow default implementation to flag the error
		return super.internalGetSetChildProperty(property, get, child);
	}

	@Override
	final int getNodeType0() {
		return IF_STATEMENT;
	}

	@Override
	ASTNode clone0(AST target) {
		IfStatement result = new IfStatement(target);
		result.setSourceRange(getStartPosition(), getLength());
		result.copyLeadingComment(this);
		result.setExpression((Expression) getExpression().clone(target));
		result.setThenStatement(
			(Statement) getThenStatement().clone(target));
		result.setElseStatement(
			(Statement) ASTNode.copySubtree(target, getElseStatement()));
		return result;
	}

	@Override
	final boolean subtreeMatch0(ASTMatcher matcher, Object other) {
		// dispatch to correct overloaded match method
		return matcher.match(this, other);
	}

	@Override
	void accept0(ASTVisitor visitor) {
		boolean visitChildren = visitor.visit(this);
		if (visitChildren) {
			// visit children in normal left to right reading order
			acceptChild(visitor, getExpression());
			acceptChild(visitor, getThenStatement());
			acceptChild(visitor, getElseStatement());
		}
		visitor.endVisit(this);
	}

	
Returns the expression of this if statement.
Returns:
the expression node/**
	 * Returns the expression of this if statement.
	 *
	 * @return the expression node
	 */
	public Expression getExpression() {
		if (this.expression == null) {
			// lazy init must be thread-safe for readers
			synchronized (this) {
				if (this.expression == null) {
					preLazyInit();
					this.expression = new SimpleName(this.ast);
					postLazyInit(this.expression, EXPRESSION_PROPERTY);
				}
			}
		}
		return this.expression;
	}

	
Sets the condition of this if statement.
Params:
expression – the expression node
Throws:
IllegalArgumentException – if:

the node belongs to a different AST
the node already has a parent
a cycle in would be created
/**
	 * Sets the condition of this if statement.
	 *
	 * @param expression the expression node
	 * @exception IllegalArgumentException if:
	 * <ul>
	 * <li>the node belongs to a different AST</li>
	 * <li>the node already has a parent</li>
	 * <li>a cycle in would be created</li>
	 * </ul>
	 */
	public void setExpression(Expression expression) {
		if (expression == null) {
			throw new IllegalArgumentException();
		}
		ASTNode oldChild = this.expression;
		preReplaceChild(oldChild, expression, EXPRESSION_PROPERTY);
		this.expression = expression;
		postReplaceChild(oldChild, expression, EXPRESSION_PROPERTY);
	}

	
Returns the "then" part of this if statement.
Returns:
the "then" statement node/**
	 * Returns the "then" part of this if statement.
	 *
	 * @return the "then" statement node
	 */
	public Statement getThenStatement() {
		if (this.thenStatement == null) {
			// lazy init must be thread-safe for readers
			synchronized (this) {
				if (this.thenStatement == null) {
					preLazyInit();
					this.thenStatement = new Block(this.ast);
					postLazyInit(this.thenStatement, THEN_STATEMENT_PROPERTY);
				}
			}
		}
		return this.thenStatement;
	}

	
Sets the "then" part of this if statement.

Special note: The Java language does not allow a local variable declaration
to appear as the "then" part of an if statement (they may only appear within a
block). However, the AST will allow a VariableDeclarationStatement
as the thenStatement of a IfStatement. To get something that will
compile, be sure to embed the VariableDeclarationStatement
inside a Block.

Params:
statement – the "then" statement node
Throws:
IllegalArgumentException – if:

the node belongs to a different AST
the node already has a parent
a cycle in would be created
/**
	 * Sets the "then" part of this if statement.
	 * <p>
	 * Special note: The Java language does not allow a local variable declaration
	 * to appear as the "then" part of an if statement (they may only appear within a
	 * block). However, the AST will allow a <code>VariableDeclarationStatement</code>
	 * as the thenStatement of a <code>IfStatement</code>. To get something that will
	 * compile, be sure to embed the <code>VariableDeclarationStatement</code>
	 * inside a <code>Block</code>.
	 * </p>
	 *
	 * @param statement the "then" statement node
	 * @exception IllegalArgumentException if:
	 * <ul>
	 * <li>the node belongs to a different AST</li>
	 * <li>the node already has a parent</li>
	 * <li>a cycle in would be created</li>
	 * </ul>
	 */
	public void setThenStatement(Statement statement) {
		if (statement == null) {
			throw new IllegalArgumentException();
		}
		ASTNode oldChild = this.thenStatement;
		preReplaceChild(oldChild, statement, THEN_STATEMENT_PROPERTY);
		this.thenStatement = statement;
		postReplaceChild(oldChild, statement, THEN_STATEMENT_PROPERTY);
	}

	
Returns the "else" part of this if statement, or null if
this if statement has no "else" part.

Note that there is a subtle difference between having no else
statement and having an empty statement ("{}") or null statement (";").

Returns:
the "else" statement node, or null if none/**
	 * Returns the "else" part of this if statement, or <code>null</code> if
	 * this if statement has <b>no</b> "else" part.
	 * <p>
	 * Note that there is a subtle difference between having no else
	 * statement and having an empty statement ("{}") or null statement (";").
	 * </p>
	 *
	 * @return the "else" statement node, or <code>null</code> if none
	 */
	public Statement getElseStatement() {
		return this.optionalElseStatement;
	}

	
Sets or clears the "else" part of this if statement.

Note that there is a subtle difference between having no else part
(as in "if(true){}") and having an empty block (as in
"if(true){}else{}") or null statement (as in "if(true){}else;").


Special note: The Java language does not allow a local variable declaration
to appear as the "else" part of an if statement (they may only appear within a
block). However, the AST will allow a VariableDeclarationStatement
as the elseStatement of a IfStatement. To get something that will
compile, be sure to embed the VariableDeclarationStatement
inside a Block.

Params:
statement – the "else" statement node, or null if
   there is none
Throws:
IllegalArgumentException – if:

the node belongs to a different AST
the node already has a parent
a cycle in would be created
/**
	 * Sets or clears the "else" part of this if statement.
	 * <p>
	 * Note that there is a subtle difference between having no else part
	 * (as in <code>"if(true){}"</code>) and having an empty block (as in
	 * "if(true){}else{}") or null statement (as in "if(true){}else;").
	 * </p>
	 * <p>
	 * Special note: The Java language does not allow a local variable declaration
	 * to appear as the "else" part of an if statement (they may only appear within a
	 * block). However, the AST will allow a <code>VariableDeclarationStatement</code>
	 * as the elseStatement of a <code>IfStatement</code>. To get something that will
	 * compile, be sure to embed the <code>VariableDeclarationStatement</code>
	 * inside a <code>Block</code>.
	 * </p>
	 *
	 * @param statement the "else" statement node, or <code>null</code> if
	 *    there is none
	 * @exception IllegalArgumentException if:
	 * <ul>
	 * <li>the node belongs to a different AST</li>
	 * <li>the node already has a parent</li>
	 * <li>a cycle in would be created</li>
	 * </ul>
	 */
	public void setElseStatement(Statement statement) {
		ASTNode oldChild = this.optionalElseStatement;
		preReplaceChild(oldChild, statement, ELSE_STATEMENT_PROPERTY);
		this.optionalElseStatement = statement;
		postReplaceChild(oldChild, statement, ELSE_STATEMENT_PROPERTY);
	}

	@Override
	int memSize() {
		return super.memSize() + 3 * 4;
	}

	@Override
	int treeSize() {
		return
			memSize()
			+ (this.expression == null ? 0 : getExpression().treeSize())
			+ (this.thenStatement == null ? 0 : getThenStatement().treeSize())
			+ (this.optionalElseStatement == null ? 0 : getElseStatement().treeSize());
	}
}