EditableSqlCheck.java

package net.sourceforge.squirrel_sql.client.session;

import java.util.regex.Pattern;
import java.util.regex.Matcher;


public class EditableSqlCheck
{
   private static final int ALLOWS_EDITING_FALSE = 0;
   private static final int ALLOWS_EDITING_TRUE = 1;
   private static final int ALLOWS_EDITING_UNKNOWN = 2;

   private String _tableNameFromSQL = null;

   public EditableSqlCheck(SQLExecutionInfo exInfo)
   {
      if(null == exInfo || null == exInfo.getSQL())
      {
         return;
      }

      _tableNameFromSQL = getTableFromSQLIntern(exInfo.getSQL());
   }

   private String getTableFromSQLIntern(String sql)
   {
       
      Pattern patternBeforeTable = Pattern.compile("SELECT\\s+[A-Z0-9_\\*\\.',\\s]*\\s+FROM\\s+([A-Z0-9_\\.]+)");
      sql = sql.toUpperCase().trim();
      // Bug 1371587 - remove useless accent characters if they exist
      sql = sql.replaceAll("\\`", "");
      Matcher matcher;

      matcher = patternBeforeTable.matcher(sql);
      if(false == matcher.find())
      {
         return null;
      }
      String table = matcher.group(1);
      String behindTable = sql.substring(matcher.end(1)).trim();

      int ret = behindTableAllowsEditing(behindTable);

      if(ALLOWS_EDITING_UNKNOWN == ret)
      {
         // This might be because an table alias is used maybe with an AS before it.

         Pattern patternBehindTable;
         if(behindTable.startsWith("AS") && 2 < behindTable.length() && Character.isWhitespace(behindTable.charAt(2)))
         {
            patternBehindTable = Pattern.compile("AS\\s+([A-Z0-9_]+)\\s+");
         }
         else
         {
            patternBehindTable = Pattern.compile("([A-Z0-9_]+)\\s+|[A-Z0-9_]+$");
         }

         matcher = patternBehindTable.matcher(behindTable);
         if(false == matcher.find())
         {
            return null;
         }

         String alias = matcher.group(0);
         String behindAlias = behindTable.substring(matcher.end(0)).trim();

         ret = behindTableAllowsEditing(behindAlias);

         if(ALLOWS_EDITING_TRUE == ret)
         {
            return table;
         }
         else
         {
            return null;
         }
      }
      else if(ALLOWS_EDITING_TRUE == ret)
      {
         return table;
      }
      else //(ALLOWS_EDITING_FALSE == ret)
      {
         return null;
      }
   }

   private int behindTableAllowsEditing(String behindTable)
   {
      if(0 == behindTable.length())
      {
         return ALLOWS_EDITING_TRUE;
      }
      else if(   behindTable.startsWith("WHERE")
         || behindTable.startsWith("ORDER")
         || behindTable.startsWith("GROUP"))
      {
         return ALLOWS_EDITING_TRUE;
      }
      else if(   behindTable.startsWith(",")
         || behindTable.startsWith("INNER")
         || behindTable.startsWith("LEFT")
         || behindTable.startsWith("RIGHT")
         || behindTable.startsWith("OUTER")
         || behindTable.startsWith(","))
      {
         return ALLOWS_EDITING_FALSE;
      }
      else
      {
         return ALLOWS_EDITING_UNKNOWN;
      }
   }




   public boolean allowsEditing()
   {
      return null != _tableNameFromSQL;
   }

   public String getTableNameFromSQL()
   {
      return _tableNameFromSQL;
   }
}