ExpressionBuilder.java :  » ERP-CRM-Financial » csheets » csheets » core » formula » util » Java Open Source

/*
 * Copyright (c) 2005 Einar Pehrson <einar@pehrson.nu>.
 *
 * This file is part of
 * CleanSheets - a spreadsheet application for the Java platform.
 *
 * CleanSheets is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * CleanSheets is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with CleanSheets; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package csheets.core.formula.util;
  
import csheets.core.formula.BinaryOperation;
import csheets.core.formula.Expression;
import csheets.core.formula.FunctionCall;
import csheets.core.formula.Literal;
import csheets.core.formula.Reference;
import csheets.core.formula.UnaryOperation;
import csheets.core.formula.compiler.IllegalFunctionCallException;
import csheets.core.formula.lang.CellReference;
import csheets.core.formula.lang.ReferenceOperation;

/**
 * A base-class for classes that rebuild expressions. In this form, it simply
 * copies expressions.
 * @author Einar Pehrson
 */
public class ExpressionBuilder implements ExpressionVisitor {

  /**
   * Creates a new expression builder.
   */
  public ExpressionBuilder() {}

  /**
   * Returns a copy of the given expression.
   * @param expression the expression to rebuild
   * @return the rebuilt expression
   */
  public Expression getExpression(Expression expression) {
    return (Expression)expression.accept(this);
  }

  public Expression visitLiteral(Literal literal) {
    return new Literal(literal.getValue());
  }

  public Expression visitUnaryOperation(UnaryOperation operation) {
    Expression operand = (Expression)operation.getOperand().accept(this);
    return new UnaryOperation(operation.getOperator(), operand);
  }

  public Expression visitBinaryOperation(BinaryOperation operation) {
    Expression leftOperand = (Expression)operation.getLeftOperand().accept(this);
    Expression rightOperand = (Expression)operation.getRightOperand().accept(this);
    return new BinaryOperation(leftOperand, operation.getOperator(), rightOperand);
  }

  public Expression visitReference(Reference reference) {
    if (reference instanceof CellReference) {
      CellReference cellRef = (CellReference)reference;
      return new CellReference(cellRef.getCell(),
        cellRef.isColumnAbsolute(), cellRef.isRowAbsolute());
    } else {
      ReferenceOperation refOp = (ReferenceOperation)reference;
      return new ReferenceOperation(
        (Reference)refOp.getLeftOperand().accept(this),
        refOp.getOperator(),
        (Reference)refOp.getRightOperand().accept(this));
    }
  }

  public Expression visitFunctionCall(FunctionCall call) {
    Expression[] arguments = call.getArguments();
    Expression[] newArguments = new Expression[arguments.length];
    int i = 0;
    for (Expression argument : arguments)
      newArguments[i++] = (Expression)argument.accept(this);
    try {
      return new FunctionCall(call.getFunction(), newArguments);
    } catch (IllegalFunctionCallException e) {
      // Doesn't happen
      return null;
    }
  }
}