de.akquinet.jbosscc.guttenbase.sql.SQLLexer Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of GuttenBase Show documentation
Copying done right...
There is a newer version: 2.1.0
package de.akquinet.jbosscc.guttenbase.sql;

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

/**
 * Primitive implementation of SQL parser in order to check validity for script execution.
 * 
 * 
 * © 2012 akquinet tech@spree
 * 
 * 
 * @author M. Dahm
 */
public class SQLLexer {
  private static final int EOF = -1;

  private final String _sql;
  private int _currentIndex = 0;

  private boolean _withinString;

  public SQLLexer(final List lines) {
    final StringBuilder builder = new StringBuilder();

    for (final String line : lines) {
      builder.append(line.trim());
      builder.append('\n');
    }

    _sql = builder.toString();
  }

  public List parse() {
    final List result = new ArrayList();
    final StringBuilder builder = new StringBuilder();

    while (hasNext()) {
      final SQLTokenType nextToken = nextToken();

      switch (nextToken) {
      case END_OF_LINE:
      case WHITESPACE:
        read();
        builder.append(' ');

        while (nextToken() == SQLTokenType.WHITESPACE) {
          read();
        }

        break;

      case END_OF_STATEMENT:
        read();
        result.add(builder.toString().trim());
        builder.setLength(0);
        break;

      case SINGLE_LINE_COMMENT_START:
        seekToken(SQLTokenType.END_OF_LINE);
        break;

      case MULTI_LINE_COMMENT_START:
        seekToken(SQLTokenType.MULTI_LINE_COMMENT_END);
        break;

      case MULTI_LINE_COMMENT_END:
        read();
        read();
        break;

      case ESCAPED_STRING_DELIMITER:
        builder.append((char) read());
        builder.append((char) read());
        break;

      case EOF:
        read();
        break;

      case OTHER:
        builder.append((char) read());
        break;

      case STRING_DELIMITER_START:
        builder.append((char) read());
        _withinString = true;
        break;

      case STRING_DELIMITER_END:
        builder.append((char) read());
        _withinString = false;
        break;

      default:
        throw new IllegalStateException("unhandled case: " + nextToken);
      }
    }

    return result;
  }

  private void seekToken(final SQLTokenType tokenType) {
    SQLTokenType nextToken;

    do {
      read();
      nextToken = nextToken();
    } while (nextToken != tokenType && nextToken != SQLTokenType.EOF);
  }

  private SQLTokenType nextToken() {
    final int ch1 = read();
    final int ch2 = read();
    unread(2);

    if (ch1 < 0) {
      return SQLTokenType.EOF;
    } else if (!_withinString && ch1 == '-' && ch2 == '-') {
      return SQLTokenType.SINGLE_LINE_COMMENT_START;
    } else if (!_withinString && ch1 == '/' && ch2 == '*') {
      return SQLTokenType.MULTI_LINE_COMMENT_START;
    } else if (!_withinString && ch1 == '*' && ch2 == '/') {
      return SQLTokenType.MULTI_LINE_COMMENT_END;
    } else if (!_withinString && ch1 == ';') {
      return SQLTokenType.END_OF_STATEMENT;
    } else if (!_withinString && ch1 == '\n') {
      return SQLTokenType.END_OF_LINE;
    } else if (!_withinString && ch1 == '\r' || ch1 == '\t' || ch1 == ' ') {
      return SQLTokenType.WHITESPACE;
    } else if (ch1 == '\'' && ch2 == '\'') {
      return SQLTokenType.ESCAPED_STRING_DELIMITER;
    } else if (ch1 == '\'' && ch2 != '\'') {
      if (_withinString) {
        return SQLTokenType.STRING_DELIMITER_END;
      } else {
        return SQLTokenType.STRING_DELIMITER_START;
      }
    } else {
      return SQLTokenType.OTHER;
    }
  }

  private void unread(final int count) {
    _currentIndex -= count;
  }

  private boolean hasNext() {
    return _currentIndex < _sql.length();
  }

  private int read() {
    final int index = _currentIndex++;

    if (!hasNext()) {
      return EOF;
    } else {
      return _sql.charAt(index);
    }
  }
}