/*******************************************************************************
 * Copyright (c) 2000, 2008 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.jdt.core.dom;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Postfix expression AST node type.
 *
 * <pre>
 * PostfixExpression:
 *    Expression PostfixOperator
 * </pre>
 *
 * @since 2.0
 * @noinstantiate This class is not intended to be instantiated by clients.
 */
public class PostfixExpression extends Expression {

    /**
     * Postfix operators (typesafe enumeration).
     * <pre>
     * PostfixOperator:
     *    <b><code>++</code></b>  <code>INCREMENT</code>
     *    <b><code>--</code></b>  <code>DECREMENT</code>
     * </pre>
     */
    public static class Operator {

        /**
         * The token for the operator.
         */
        private String token;

        /**
         * Creates a new postfix operator with the given token.
         * <p>
         * Note: this constructor is private. The only instances
         * ever created are the ones for the standard operators.
         * </p>
         *
         * @param token the character sequence for the operator
         */
        private Operator(String token) {
            this.token = token;
        }

        /**
         * Returns the character sequence for the operator.
         *
         * @return the character sequence for the operator
         */
        public String toString() {
            return this.token;
        }

        /** Postfix increment "++" operator. */
        public static final Operator INCREMENT = new Operator("++");//$NON-NLS-1$
        /** Postfix decrement "--" operator. */
        public static final Operator DECREMENT = new Operator("--");//$NON-NLS-1$

        /**
         * Map from token to operator (key type: <code>String</code>;
         * value type: <code>Operator</code>).
         */
        private static final Map CODES;
        static {
            CODES = new HashMap(20);
            Operator[] ops = {
                    INCREMENT,
                    DECREMENT,
                };
            for (int i = 0; i < ops.length; i++) {
                CODES.put(ops[i].toString(), ops[i]);
            }
        }

        /**
         * Returns the postfix operator corresponding to the given string,
         * or <code>null</code> if none.
         * <p>
         * <code>toOperator</code> is the converse of <code>toString</code>:
         * that is, <code>Operator.toOperator(op.toString()) == op</code> for
         * all operators <code>op</code>.
         * </p>
         *
         * @param token the character sequence for the operator
         * @return the postfix operator, or <code>null</code> if none
         */
        public static Operator toOperator(String token) {
            return (Operator) CODES.get(token);
        }
    }

    /**
     * The "operator" structural property of this node type.
     * @since 3.0
     */
    public static final SimplePropertyDescriptor OPERATOR_PROPERTY =
        new SimplePropertyDescriptor(PostfixExpression.class, "operator", PostfixExpression.Operator.class, MANDATORY); //$NON-NLS-1$

    /**
     * The "operand" structural property of this node type.
     * @since 3.0
     */
    public static final ChildPropertyDescriptor OPERAND_PROPERTY =
        new ChildPropertyDescriptor(PostfixExpression.class, "operand", Expression.class, MANDATORY, CYCLE_RISK); //$NON-NLS-1$

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

    static {
        List propertyList = new ArrayList(3);
        createPropertyList(PostfixExpression.class, propertyList);
        addProperty(OPERAND_PROPERTY, propertyList);
        addProperty(OPERATOR_PROPERTY, propertyList);
        PROPERTY_DESCRIPTORS = reapPropertyList(propertyList);
    }

    /**
     * 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 operator; defaults to an unspecified postfix operator.
     */
    private PostfixExpression.Operator operator =
        PostfixExpression.Operator.INCREMENT;

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

    /**
     * Creates a new AST node for an postfix expression owned by the given
     * AST. By default, the node has unspecified (but legal) operator and
     * operand.
     *
     * @param ast the AST that is to own this node
     */
    PostfixExpression(AST ast) {
        super(ast);
    }

    /* (omit javadoc for this method)
     * Method declared on ASTNode.
     */
    final List internalStructuralPropertiesForType(int apiLevel) {
        return propertyDescriptors(apiLevel);
    }

    /* (omit javadoc for this method)
     * Method declared on ASTNode.
     */
    final Object internalGetSetObjectProperty(SimplePropertyDescriptor property, boolean get, Object value) {
        if (property == OPERATOR_PROPERTY) {
            if (get) {
                return getOperator();
            } else {
                setOperator((Operator) value);
                return null;
            }
        }
        // allow default implementation to flag the error
        return super.internalGetSetObjectProperty(property, get, value);
    }

    /* (omit javadoc for this method)
     * Method declared on ASTNode.
     */
    final ASTNode internalGetSetChildProperty(ChildPropertyDescriptor property, boolean get, ASTNode child) {
        if (property == OPERAND_PROPERTY) {
            if (get) {
                return getOperand();
            } else {
                setOperand((Expression) child);
                return null;
            }
        }
        // allow default implementation to flag the error
        return super.internalGetSetChildProperty(property, get, child);
    }

    /* (omit javadoc for this method)
     * Method declared on ASTNode.
     */
    final int getNodeType0() {
        return POSTFIX_EXPRESSION;
    }

    /* (omit javadoc for this method)
     * Method declared on ASTNode.
     */
    ASTNode clone0(AST target) {
        PostfixExpression result = new PostfixExpression(target);
        result.setSourceRange(getStartPosition(), getLength());
        result.setOperator(getOperator());
        result.setOperand((Expression) getOperand().clone(target));
        return result;
    }

    /* (omit javadoc for this method)
     * Method declared on ASTNode.
     */
    final boolean subtreeMatch0(ASTMatcher matcher, Object other) {
        // dispatch to correct overloaded match method
        return matcher.match(this, other);
    }

    /* (omit javadoc for this method)
     * Method declared on ASTNode.
     */
    void accept0(ASTVisitor visitor) {
        boolean visitChildren = visitor.visit(this);
        if (visitChildren) {
            acceptChild(visitor, getOperand());
        }
        visitor.endVisit(this);
    }

    /**
     * Returns the operator of this postfix expression.
     *
     * @return the operator
     */
    public PostfixExpression.Operator getOperator() {
        return this.operator;
    }

    /**
     * Sets the operator of this postfix expression.
     *
     * @param operator the operator
     * @exception IllegalArgumentException if the argument is incorrect
     */
    public void setOperator(PostfixExpression.Operator operator) {
        if (operator == null) {
            throw new IllegalArgumentException();
        }
        preValueChange(OPERATOR_PROPERTY);
        this.operator = operator;
        postValueChange(OPERATOR_PROPERTY);
    }

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

    /**
     * Sets the operand of this postfix expression.
     *
     * @param expression the operand 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 setOperand(Expression expression) {
        if (expression == null) {
            throw new IllegalArgumentException();
        }
        ASTNode oldChild = this.operand;
        preReplaceChild(oldChild, expression, OPERAND_PROPERTY);
        this.operand = expression;
        postReplaceChild(oldChild, expression, OPERAND_PROPERTY);
    }

    /* (omit javadoc for this method)
     * Method declared on ASTNode.
     */
    int memSize() {
        // treat Operator as free
        return BASE_NODE_SIZE + 2 * 4;
    }

    /* (omit javadoc for this method)
     * Method declared on ASTNode.
     */
    int treeSize() {
        return
            memSize()
            + (this.operand == null ? 0 : getOperand().treeSize());
    }
}