src/org/objectweb/cjdbc/common/sql/DeleteRequest.java

説明を見る。

package org.objectweb.cjdbc.common.sql;

import java.io.Serializable;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.StringTokenizer;

import org.objectweb.cjdbc.common.sql.schema.AliasedDatabaseTable;
import org.objectweb.cjdbc.common.sql.schema.DatabaseColumn;
import org.objectweb.cjdbc.common.sql.schema.DatabaseSchema;
import org.objectweb.cjdbc.common.sql.schema.DatabaseTable;
import org.objectweb.cjdbc.common.sql.schema.TableColumn;

public class DeleteRequest extends AbstractWriteRequest implements Serializable
{
  private transient boolean   isUnique;

  private transient ArrayList from;

  protected ArrayList         whereValues;

  public DeleteRequest(String sqlQuery, boolean escapeProcessing, int timeout,
      String lineSeparator, DatabaseSchema schema, int granularity,
      boolean isCaseSensitive) throws SQLException
  {
    this(sqlQuery, escapeProcessing, timeout, lineSeparator);
    parse(schema, granularity, isCaseSensitive);
  }

  public DeleteRequest(String sqlQuery, boolean escapeProcessing, int timeout,
      String lineSeparator)
  {
    super(sqlQuery, escapeProcessing, timeout, lineSeparator);
    cacheable = RequestType.UNCACHEABLE;
    isParsed = false;
    isUnique = false;
  }

  public void parse(DatabaseSchema schema, int granularity,
      boolean isCaseSensitive) throws SQLException
  {
    if (granularity == ParsingGranularities.NO_PARSING)
    {
      isParsed = true;
      return;
    }

    // Sanity check
    if (schema == null)
      throw new SQLException(
          "Unable to parse request with an undefined database schema");

    String originalSQL = this.trimCarriageReturn();
    String sql = originalSQL.toLowerCase();

    int fromIdx = sql.indexOf("from ");
    if (fromIdx == -1)
    {
      // For queries like: DELETE t WHERE ... used by Oracle
      fromIdx = 6; // 6 = "delete".length()
    }
    else
    {
      fromIdx += 5; // 5 = "from".length()
    }

    // Syntax is usually DELETE FROM t WHERE ... but it can be
    // DELETE t1,t2,... FROM t1,t2,.... WHERE ...
    // Let's ignore everything between DELETE and FROM, and suppose that we
    // delete from all tables (will just have a wider invalidation impact on the
    // cache).
    sql = sql.substring(fromIdx).trim();

    // Look for the WHERE clause
    int whereIdx = sql.indexOf("where ");

    if (isCaseSensitive)
      sql = originalSQL.substring(originalSQL.length() - sql.length());
    if (whereIdx == -1)
      tableName = sql;
    else
      tableName = sql.substring(0, whereIdx).trim();

    // Get the table on which DELETE occurs
    DatabaseTable t = schema.getTable(tableName, isCaseSensitive);
    if (t == null)
      throw new SQLException("Unknown table '" + tableName
          + "' in this DELETE statement: " + sqlQuery + "'");

    try
    {
      switch (granularity)
      {
        case ParsingGranularities.NO_PARSING :
          return;
        case ParsingGranularities.TABLE :
          break;
        case ParsingGranularities.COLUMN :
          from = getFromTables(tableName, schema);
          columns = getWhereColumns(sql.substring(whereIdx + 6).trim(), from);

          if (from != null)
          {
            // Convert 'from' to an ArrayList of String objects instead of
            // AliasedTables objects
            int size = from.size();
            ArrayList unaliased = new ArrayList(size);
            for (int i = 0; i < size; i++)
              unaliased.add(((AliasedDatabaseTable) from.get(i)).getTable()
                  .getName());
            from = unaliased;
          }
          break;
        case ParsingGranularities.COLUMN_UNIQUE :
          from = getFromTables(tableName, schema);
          columns = getWhereColumns(sql.substring(whereIdx + 6).trim(), from);

          if (from != null)
          {
            // Convert 'from' to an ArrayList of String objects instead of
            // AliasedTables objects
            int size = from.size();
            ArrayList unaliased = new ArrayList(size);
            for (int i = 0; i < size; i++)
              unaliased.add(((AliasedDatabaseTable) from.get(i)).getTable()
                  .getName());
            from = unaliased;
          }
          break;
        default :
          throw new SQLException("Unsupported parsing granularity: '"
              + granularity + "'");
      }
    }
    catch (SQLException e)
    {
      from = null;
      columns = null;
      whereValues = null;
      throw e;
    }

    isParsed = true;
  }

  public void cloneParsing(AbstractRequest request)
  {
    if (!request.isParsed())
      return;
    cloneTableNameAndColumns((AbstractWriteRequest) request);
    isParsed = true;
  }

  private ArrayList getFromTables(String fromClause, DatabaseSchema dbs)
      throws SQLException
  {
    StringTokenizer tables = new StringTokenizer(fromClause, ",");
    ArrayList result = new ArrayList(tables.countTokens());
    while (tables.hasMoreTokens())
    {
      String tableName = tables.nextToken().trim();
      // Check if the table has an alias
      // Example: SELECT x.price FROM item x
      String alias = null;
      int aliasIdx = tableName.indexOf(' ');
      if (aliasIdx != -1)
      {
        alias = tableName.substring(aliasIdx);
        tableName = tableName.substring(0, aliasIdx);
      }

      DatabaseTable table = dbs.getTable(tableName);
      if (table == null)
        throw new SQLException("Unknown table '" + tableName
            + "' in FROM clause of this DELETE statement: '" + sqlQuery + "'");
      result.add(new AliasedDatabaseTable(table, alias));
    }

    return result;
  }

  private ArrayList getWhereColumns(String whereClause, ArrayList aliasedFrom)
  {
    ArrayList result = new ArrayList(); // TableColumn objects
    ArrayList dbColumns = new ArrayList(); // DatabaseColumn objects

    // Instead of parsing the clause, we use a brutal force technique
    // and we try to directly identify every column name of each table.
    DatabaseColumn col;
    for (int i = 0; i < aliasedFrom.size(); i++)
    {
      DatabaseTable t = ((AliasedDatabaseTable) aliasedFrom.get(i)).getTable();
      ArrayList cols = t.getColumns();
      int size = cols.size();
      for (int j = 0; j < size; j++)
      {
        col = (DatabaseColumn) cols.get(j);
        // if pattern found and column not already in result, it's a dependency
        // !
        int matchIdx = whereClause.indexOf(col.getName());
        while (matchIdx > 0)
        {
          // Try to check that we got the full pattern and not a sub-pattern
          char beforePattern = whereClause.charAt(matchIdx - 1);
          // Everything should be lowercase here
          if (((beforePattern >= 'a') && (beforePattern <= 'z')) // Everything
              || (beforePattern == '_'))
            matchIdx = whereClause.indexOf(col.getName(), matchIdx + 1);
          else
            break;
        }
        if (matchIdx == -1)
          continue;
        result.add(new TableColumn(t.getName(), col.getName()));
        if (col.isUnique())
          pkValue = col.getName();
        dbColumns.add(col);
      }
    }

    return result;
  }

  public ArrayList getValues()
  {
    return whereValues;
  }

  public boolean isUnique()
  {
    return isUnique;
  }

  public boolean isInsert()
  {
    return false;
  }

  public boolean isUpdate()
  {
    return false;
  }

  public boolean isDelete()
  {
    return true;
  }

  public boolean isCreate()
  {
    return false;
  }

  public boolean isDrop()
  {
    return false;
  }

  public void debug()
  {
    super.debug();
    System.out.println("Is unique: " + isUnique);
    if (tableName != null)
      System.out.println("Deleted table: " + tableName);
    else
      System.out.println("No information about deleted table");

    if (columns != null)
    {
      System.out.println("Columns columns:");
      for (int i = 0; i < columns.size(); i++)
        System.out.println("  "
            + ((TableColumn) columns.get(i)).getColumnName());
    }
    else
      System.out.println("No information about updated columns");

    System.out.println();
  }

  public boolean isAlter()
  {
    return false;
  }
}

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