StringEscapesProcessor.java :  » RSS-RDF » sesame » org » openrdf » query » parser » serql » Java Open Source

/*
 * Copyright Aduna (http://www.aduna-software.com/) (c) 1997-2007.
 *
 * Licensed under the Aduna BSD-style license.
 */
package org.openrdf.query.parser.serql;

import org.openrdf.query.MalformedQueryException;
import org.openrdf.query.parser.serql.ast.ASTLiteral;
import org.openrdf.query.parser.serql.ast.ASTQueryContainer;
import org.openrdf.query.parser.serql.ast.ASTString;
import org.openrdf.query.parser.serql.ast.VisitorException;

/**
 * Processes escape sequences in strings, replacing the escape sequence with
 * their actual value. Escape sequences for SPARQL are documented in section <a
 * href="http://www.w3.org/TR/rdf-sparql-query/#grammarEscapes">A.7 Escape
 * sequences in strings</a>.
 * 
 * @author Arjohn Kampman
 */
class StringEscapesProcessor {

  /**
   * Processes escape sequences in ASTString objects.
   * 
   * @param qc
   *        The query that needs to be processed.
   * @throws MalformedQueryException
   *         If an invalid escape sequence was found.
   */
  public static void process(ASTQueryContainer qc)
    throws MalformedQueryException
  {
    StringProcessor visitor = new StringProcessor();
    try {
      qc.jjtAccept(visitor, null);
    }
    catch (VisitorException e) {
      throw new MalformedQueryException(e.getMessage(), e);
    }
  }

  private static class StringProcessor extends ASTVisitorBase {

    public StringProcessor() {
    }

    @Override
    public Object visit(ASTString stringNode, Object data)
      throws VisitorException
    {
      String value = stringNode.getValue();
      try {
        value = SeRQLUtil.decodeString(value);
        stringNode.setValue(value);
      }
      catch (IllegalArgumentException e) {
        // Invalid escape sequence
        throw new VisitorException(e.getMessage());
      }

      return super.visit(stringNode, data);
    }

    @Override
    public Object visit(ASTLiteral literalNode, Object data)
      throws VisitorException
    {
      String label = literalNode.getLabel();
      try {
        label = SeRQLUtil.decodeString(label);
        literalNode.setLabel(label);
      }
      catch (IllegalArgumentException e) {
        // Invalid escape sequence
        throw new VisitorException(e.getMessage());
      }

      return super.visit(literalNode, data);
    }
  }
}