001 /*
002 * Copyright (c) 2005 Einar Pehrson <einar@pehrson.nu>.
003 *
004 * This file is part of
005 * CleanSheets - a spreadsheet application for the Java platform.
006 *
007 * CleanSheets is free software; you can redistribute it and/or modify
008 * it under the terms of the GNU General Public License as published by
009 * the Free Software Foundation; either version 2 of the License, or
010 * (at your option) any later version.
011 *
012 * CleanSheets is distributed in the hope that it will be useful,
013 * but WITHOUT ANY WARRANTY; without even the implied warranty of
014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
015 * GNU General Public License for more details.
016 *
017 * You should have received a copy of the GNU General Public License
018 * along with CleanSheets; if not, write to the Free Software
019 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
020 */
021 package csheets.core.formula.util;
022
023 import csheets.core.formula.BinaryOperation;
024 import csheets.core.formula.Expression;
025 import csheets.core.formula.FunctionCall;
026 import csheets.core.formula.Literal;
027 import csheets.core.formula.Reference;
028 import csheets.core.formula.UnaryOperation;
029 import csheets.core.formula.compiler.IllegalFunctionCallException;
030 import csheets.core.formula.lang.CellReference;
031 import csheets.core.formula.lang.ReferenceOperation;
032
033 /**
034 * A base-class for classes that rebuild expressions. In this form, it simply
035 * copies expressions.
036 * @author Einar Pehrson
037 */
038 public class ExpressionBuilder implements ExpressionVisitor {
039
040 /**
041 * Creates a new expression builder.
042 */
043 public ExpressionBuilder() {}
044
045 /**
046 * Returns a copy of the given expression.
047 * @param expression the expression to rebuild
048 * @return the rebuilt expression
049 */
050 public Expression getExpression(Expression expression) {
051 return (Expression)expression.accept(this);
052 }
053
054 public Expression visitLiteral(Literal literal) {
055 return new Literal(literal.getValue());
056 }
057
058 public Expression visitUnaryOperation(UnaryOperation operation) {
059 Expression operand = (Expression)operation.getOperand().accept(this);
060 return new UnaryOperation(operation.getOperator(), operand);
061 }
062
063 public Expression visitBinaryOperation(BinaryOperation operation) {
064 Expression leftOperand = (Expression)operation.getLeftOperand().accept(this);
065 Expression rightOperand = (Expression)operation.getRightOperand().accept(this);
066 return new BinaryOperation(leftOperand, operation.getOperator(), rightOperand);
067 }
068
069 public Expression visitReference(Reference reference) {
070 if (reference instanceof CellReference) {
071 CellReference cellRef = (CellReference)reference;
072 return new CellReference(cellRef.getCell(),
073 cellRef.isColumnAbsolute(), cellRef.isRowAbsolute());
074 } else {
075 ReferenceOperation refOp = (ReferenceOperation)reference;
076 return new ReferenceOperation(
077 (Reference)refOp.getLeftOperand().accept(this),
078 refOp.getOperator(),
079 (Reference)refOp.getRightOperand().accept(this));
080 }
081 }
082
083 public Expression visitFunctionCall(FunctionCall call) {
084 Expression[] arguments = call.getArguments();
085 Expression[] newArguments = new Expression[arguments.length];
086 int i = 0;
087 for (Expression argument : arguments)
088 newArguments[i++] = (Expression)argument.accept(this);
089 try {
090 return new FunctionCall(call.getFunction(), newArguments);
091 } catch (IllegalFunctionCallException e) {
092 // Doesn't happen
093 return null;
094 }
095 }
096 }