/*
* 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.
*/
package org.apache.commons.csv;
import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import static org.apache.commons.csv.Token.Type.*;
/**
* Parses CSV files according to the specified configuration.
*
* Because CSV appears in many different dialects, the parser supports many
* configuration settings by allowing the specification of a {@link CSVFormat}.
*
* <p>Parsing of a csv-string having tabs as separators,
* '"' as an optional value encapsulator, and comments starting with '#':</p>
* <pre>
* CSVFormat format = new CSVFormat('\t', '"', '#');
* Reader in = new StringReader("a\tb\nc\td");
* List<CSVRecord> records = new CSVParser(in, format).getRecords();
* </pre>
*
* <p>Parsing of a csv-string in Excel CSV format, using a for-each loop:</p>
* <pre>
* Reader in = new StringReader("a;b\nc;d");
* CSVParser parser = new CSVParser(in, CSVFormat.EXCEL);
* for (CSVRecord record : parser) {
* ...
* }
* </pre>
*
* <p>
* Internal parser state is completely covered by the format
* and the reader-state.</p>
*
* <p>see <a href="package-summary.html">package documentation</a>
* for more details</p>
*/
public class CSVParser implements Iterable<CSVRecord> {
private final Lexer lexer;
private final Map<String, Integer> headerMapping;
// the following objects are shared to reduce garbage
/** A record buffer for getRecord(). Grows as necessary and is reused. */
private final List<String> record = new ArrayList<String>();
private final Token reusableToken = new Token();
/**
* CSV parser using the default {@link CSVFormat}.
*
* @param input a Reader containing "csv-formatted" input
* @throws IllegalArgumentException thrown if the parameters of the format are inconsistent
*/
public CSVParser(Reader input) throws IOException {
this(input, CSVFormat.DEFAULT);
}
/**
* Customized CSV parser using the given {@link CSVFormat}
*
* @param input a Reader containing "csv-formatted" input
* @param format the CSVFormat used for CSV parsing
* @throws IllegalArgumentException thrown if the parameters of the format are inconsistent
*/
public CSVParser(Reader input, CSVFormat format) throws IOException {
format.validate();
this.lexer = new CSVLexer(format, new ExtendedBufferedReader(input));
this.headerMapping = initializeHeader(format);
}
/**
* Customized CSV parser using the given {@link CSVFormat}
*
* @param input a String containing "csv-formatted" input
* @param format the CSVFormat used for CSV parsing
* @throws IllegalArgumentException thrown if the parameters of the format are inconsistent
*/
public CSVParser(String input, CSVFormat format) throws IOException{
this(new StringReader(input), format);
}
/**
* Parses the CSV input according to the given format and returns the content
* as an array of {@link CSVRecord} entries.
* <p/>
* The returned content starts at the current parse-position in the stream.
*
* @return list of {@link CSVRecord} entries, may be empty
* @throws IOException on parse error or input read-failure
*/
public List<CSVRecord> getRecords() throws IOException {
List<CSVRecord> records = new ArrayList<CSVRecord>();
CSVRecord rec;
while ((rec = getRecord()) != null) {
records.add(rec);
}
return records;
}
/**
* Parses the next record from the current point in the stream.
*
* @return the record as an array of values, or <tt>null</tt> if the end of the stream has been reached
* @throws IOException on parse error or input read-failure
*/
CSVRecord getRecord() throws IOException {
CSVRecord result = new CSVRecord(null, headerMapping, null);
record.clear();
StringBuilder sb = null;
do {
reusableToken.reset();
lexer.nextToken(reusableToken);
switch (reusableToken.type) {
case TOKEN:
record.add(reusableToken.content.toString());
break;
case EORECORD:
record.add(reusableToken.content.toString());
break;
case EOF:
if (reusableToken.isReady) {
record.add(reusableToken.content.toString());
} else {
result = null;
}
break;
case INVALID:
throw new IOException("(line " + getLineNumber() + ") invalid parse sequence");
case COMMENT: // Ignored currently
if (sb == null) { // first comment for this record
sb = new StringBuilder();
} else {
sb.append("\n");
}
sb.append(reusableToken.content);
reusableToken.type = TOKEN; // Read another token
break;
}
} while (reusableToken.type == TOKEN);
if (!record.isEmpty()) {
result = new CSVRecord(record.toArray(new String[record.size()]), headerMapping,
sb == null ? null : sb.toString());
}
return result;
}
/**
* Initializes the name to index mapping if the format defines a header.
*/
private Map<String, Integer> initializeHeader(CSVFormat format) throws IOException {
Map<String, Integer> hdrMap = null;
if (format.getHeader() != null) {
hdrMap = new HashMap<String, Integer>();
String[] header = null;
if (format.getHeader().length == 0) {
// read the header from the first line of the file
CSVRecord rec = getRecord();
if (rec != null) {
header = rec.values();
}
} else {
header = format.getHeader();
}
// build the name to index mappings
if (header != null) {
for (int i = 0; i < header.length; i++) {
hdrMap.put(header[i], Integer.valueOf(i));
}
}
}
return hdrMap;
}
/**
* Returns an iterator on the records. IOExceptions occuring
* during the iteration are wrapped in a RuntimeException.
*/
public Iterator<CSVRecord> iterator() {
return new Iterator<CSVRecord>() {
private CSVRecord current;
public boolean hasNext() {
if (current == null) {
current = getNextRecord();
}
return current != null;
}
public CSVRecord next() {
CSVRecord next = current;
current = null;
if (next == null) {
// hasNext() wasn't called before
next = getNextRecord();
if (next == null) {
throw new NoSuchElementException("No more CSV records available");
}
}
return next;
}
private CSVRecord getNextRecord() {
try {
return getRecord();
} catch (IOException e) {
throw new RuntimeException(e);
}
}
public void remove() {
throw new UnsupportedOperationException();
}
};
}
/**
* Returns the current line number in the input stream.
* <p/>
* ATTENTION: in case your csv has multiline-values the returned
* number does not correspond to the record-number
*
* @return current line number
*/
public int getLineNumber() {
return lexer.getLineNumber();
}
}