package org.apache.fulcrum.parser;

 /*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you under the Apache License, Version 2.0 (the

  * "License"); you may not use this file except in compliance

  * with the License.  You may obtain a copy of the License at

  *

  *   http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing,

  * software distributed under the License is distributed on an

  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

  * KIND, either express or implied.  See the License for the

  * specific language governing permissions and limitations

  * under the License.

  */

 import java.io.BufferedReader;

 import java.io.IOException;

 import java.io.InputStreamReader;

 import java.io.Reader;

 import java.io.StreamTokenizer;

 import java.util.ArrayList;

 import java.util.Iterator;

 import java.util.List;

 import java.util.NoSuchElementException;

 import org.apache.avalon.framework.logger.LogEnabled;

 import org.apache.avalon.framework.logger.Logger;

 /**

  * DataStreamParser is used to parse a stream with a fixed format and

  * generate ValueParser objects which can be used to extract the values

  * in the desired type.

  *

  * <p>The class itself is abstract - a concrete subclass which implements

  * the initTokenizer method such as CSVParser or TSVParser is required

  * to use the functionality.

  *

  * <p>The class implements the java.util.Iterator interface for convenience.

  * This allows simple use in a Velocity template for example:

  *

  * <pre>

  * #foreach ($row in $datastream)

  *   Name: $row.Name

  *   Description: $row.Description

  * #end

  * </pre>

  *

  * @author <a href="mailto:sean@informage.net">Sean Legassick</a>

  * @version $Id: DataStreamParser.java 1844836 2018-10-25 14:59:49Z painter $

  */

 public abstract class DataStreamParser

     implements Iterator<ValueParser>, LogEnabled

 {

     /**

      * The list of column names.

      */

     private List<String>    columnNames;

     /**

      * The stream tokenizer for reading values from the input reader.

      */

     private final StreamTokenizer tokenizer;

     /**

      * The parameter parser holding the values of columns for the current line.

      */

     private ValueParser     lineValues;

     /**

      * Indicates whether or not the tokenizer has read anything yet.

      */

     private boolean         neverRead = true;

     /**

      * The character encoding of the input

      */

     private String          characterEncoding;

     /**

      * Logger to use

      */

     protected Logger log;

     /**

      * Create a new DataStreamParser instance. Requires a Reader to read the

      * comma-separated values from, a list of column names and a

      * character encoding.

      *

      * @param in the input reader.

      * @param columnNames a list of column names.

      * @param characterEncoding the character encoding of the input.

      */

     public DataStreamParser(Reader in, List<String> columnNames,

             String characterEncoding)

     {

         this.columnNames = columnNames;

         this.characterEncoding = characterEncoding;

         if (this.characterEncoding == null)

         {

             // try and get the characterEncoding from the reader

             this.characterEncoding = "US-ASCII";

             try

             {

                 this.characterEncoding = ((InputStreamReader)in).getEncoding();

             }

             catch (ClassCastException e)

             {

                 // ignore

             }

         }

         tokenizer = new StreamTokenizer(new BufferedReader(in));

         initTokenizer(tokenizer);

     }

     /**

      * Initialize the StreamTokenizer instance used to read the lines

      * from the input reader. This must be implemented in subclasses to

      * set up the tokenizing properties.

      * 

      * @param tokenizer the StreamTokenizer to use

      */

     protected abstract void initTokenizer(StreamTokenizer tokenizer);

     /**

      * Provide a logger

      *

      * @see org.apache.avalon.framework.logger.LogEnabled#enableLogging(org.apache.avalon.framework.logger.Logger)

      */

     public void enableLogging(Logger logger)

     {

         this.log = logger.getChildLogger("DataStreamParser");

     }

     /**

      * Set the list of column names explicitly.

      *

      * @param columnNames A list of column names.

      */

     public void setColumnNames(List<String> columnNames)

     {

         this.columnNames = columnNames;

     }

     /**

      * Read the list of column names from the input reader using the

      * tokenizer.

      *

      * @exception IOException an IOException occurred.

      */

     public void readColumnNames()

         throws IOException

     {

         columnNames = new ArrayList<String>();

         neverRead = false;

         tokenizer.nextToken();

         while (tokenizer.ttype == StreamTokenizer.TT_WORD

                || tokenizer.ttype == '"')

         {

             columnNames.add(tokenizer.sval);

             tokenizer.nextToken();

         }

     }

     /**

      * Determine whether a further row of values exists in the input.

      *

      * @return true if the input has more rows.

      * @exception IOException an IOException occurred.

      */

     public boolean hasNextRow()

         throws IOException

     {

         // check for end of line ensures that an empty last line doesn't

         // give a false positive for hasNextRow

         if (neverRead || tokenizer.ttype == StreamTokenizer.TT_EOL)

         {

             tokenizer.nextToken();

             tokenizer.pushBack();

             neverRead = false;

         }

         return tokenizer.ttype != StreamTokenizer.TT_EOF;

     }

     /**

      * Returns a ValueParser object containing the next row of values.

      *

      * @return a ValueParser object.

      * @exception IOException an IOException occurred.

      * @exception NoSuchElementException there are no more rows in the input.

      */

     public ValueParser nextRow()

         throws IOException, NoSuchElementException

     {

         if (!hasNextRow())

         {

             throw new NoSuchElementException();

         }

         if (lineValues == null)

         {

             lineValues = new BaseValueParser(characterEncoding);

         }

         else

         {

             lineValues.clear();

         }

         Iterator<String> it = columnNames.iterator();

         tokenizer.nextToken();

         while (tokenizer.ttype == StreamTokenizer.TT_WORD

                || tokenizer.ttype == '"')

         {

             // note this means that if there are more values than

             // column names, the extra values are discarded.

             if (it.hasNext())

             {

                 String colname = it.next().toString();

                 String colval  = tokenizer.sval;

                 if (log.isDebugEnabled())

                 {

                     log.debug("DataStreamParser.nextRow(): " +

                               colname + '=' + colval);

                 }

                 lineValues.add(colname, colval);

             }

             tokenizer.nextToken();

         }

         return lineValues;

     }

     /**

      * Determine whether a further row of values exists in the input.

      *

      * @return true if the input has more rows.

      */

     public boolean hasNext()

     {

         boolean hasNext = false;

         try

         {

             hasNext = hasNextRow();

         }

         catch (IOException e)

         {

             log.error("IOException in CSVParser.hasNext", e);

         }

         return hasNext;

     }

     /**

      * Returns a ValueParser object containing the next row of values.

      *

      * @return a ValueParser object as an Object.

      * @exception NoSuchElementException there are no more rows in the input

      *                                   or an IOException occurred.

      */

     public ValueParser next()

         throws NoSuchElementException

     {

         ValueParser nextRow = null;

         try

         {

             nextRow = nextRow();

         }

         catch (IOException e)

         {

             log.error("IOException in CSVParser.next", e);

             throw new NoSuchElementException();

         }

         return nextRow;

     }

     /**

      * The optional Iterator.remove method is not supported.

      *

      * @exception UnsupportedOperationException the operation is not supported.

      */

     public void remove()

         throws UnsupportedOperationException

     {

         throw new UnsupportedOperationException();

     }

 }