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/*
* LingPipe v. 4.1.0
* Copyright (C) 2003-2011 Alias-i
*
* This program is licensed under the Alias-i Royalty Free License
* Version 1 WITHOUT ANY WARRANTY, without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the Alias-i
* Royalty Free License Version 1 for more details.
*
* You should have received a copy of the Alias-i Royalty Free License
* Version 1 along with this program; if not, visit
* http://alias-i.com/lingpipe/licenses/lingpipe-license-1.txt or contact
* Alias-i, Inc. at 181 North 11th Street, Suite 401, Brooklyn, NY 11211,
* +1 (718) 290-9170.
*/
package com.aliasi.corpus;
import com.aliasi.util.Files;
import com.aliasi.util.Strings;
import org.xml.sax.InputSource;
import java.io.File;
import java.io.IOException;
/**
* The Parser abstract class provides methods for parsing
* content from an input source or character sequence and passing
* extracted events to a content handler. Concrete implementations will
* typically make assumptions about the type of the handler.
*
* Concrete subclasses must implement both {@link
* #parse(InputSource)} and {@link #parseString(char[],int,int)}. Two
* subclasses of this class, {@link InputSourceParser} and {@link
* StringParser} may be extended by implementing only one of the
* above methods.
*
* @author Bob Carpenter
* @version 4.0.1
* @since LingPipe2.1
* @param the type of handler which receives events from this parser
*/
public abstract class Parser {
private H mHandler;
/**
* Construct a parser with a null handler.
*/
public Parser() {
this(null);
}
/**
* Construct a parser with the specified handler.
*
* @param handler Current handler.
*/
public Parser(H handler) {
mHandler = handler;
}
/**
* Sets the content handler to the specified value. The current
* handler is used for all content extracted by this parser.
*
* @param handler Handler to use for content extracted from parsed
* content.
*/
public void setHandler(H handler) {
mHandler = handler;
}
/**
* Returns the current content handler. The current handler is
* applied to all extracted content.
*
* @return Current content handler.
*/
public H getHandler() {
return mHandler;
}
/**
* Parse the specified system identifier, usually a URL name,
* passing extracted events to the handler.
*
* The implementation provided by this abstract class
* constructs an input source from the system identifier
* and passes it to {@link #parse(InputSource)}.
*
*
Warning: This method does not specify a character
* encoding. Behavior will depend on the implementation.
* See {@link #parse(String,String)} to set the encoding.
*
* @param sysId System ID from which to read.
* @throws IOException If there is an exception reading
* from the specified source.
*/
public void parse(String sysId) throws IOException {
InputSource in = new InputSource(sysId);
parse(in);
}
/**
* Parse the specified system identifier, usually a URL name,
* using the specified character encoding, passing extracted
* events to the handler.
*
*
Warning: The character encoding is set on the
* constructed input source, but this may be ignored by the
* parser.
*
* @param sysId System identifier for data, typically a URL name.
* @param charEncoding Character encoding to use for the data.
*/
public void parse(String sysId, String charEncoding) throws IOException {
InputSource in = new InputSource(sysId);
in.setEncoding(charEncoding);
parse(in);
}
/**
* Parse the specified file, passing extracted events to the
* handler.
*
*
The file is converted to a URL name using
* {@code File.toURI().toURL().toString()}. It is then used
* to construct an input source which is parsed using
* the {@code #parse(InputSource)} method.
*
*
Warning: This method does not specify a character
* encoding on the constructed input source. Behavior will depend
* on the implementation. See {@link #parse(File,String)} to set
* the character encoding.
*
* @param file File to parse.
* @throws IOException If there is an exception reading
* from the specified file or it does not exist.
*/
public void parse(File file) throws IOException {
parse(file.toURI().toURL().toString());
}
/**
* Parse the specified file using the specified character
* encoding, passing events to the handler.
*
*
The file is converted to a URL name using
* {@code File.toURI().toURL().toString()}.
*
*
Warning: The character encoding will be set on the
* input source for parsing, but parser implementations may
* choose to ignore it.
*
* @param file File from which to read.
* @param charEncoding Characte encoding for text.
* @throws IOException If there is an exception reading
* from the specified source.
*/
public void parse(File file, String charEncoding)
throws IOException {
String urlName = file.toURI().toURL().toString();
InputSource in = new InputSource(urlName);
in.setEncoding(charEncoding);
parse(in);
}
/**
* Parse the specified character sequence. Extracted content
* is passed to the current handler.
*
*
The character sequence is converted to a character array
* using {@link Strings#toCharArray(CharSequence)} and then
* passed as a slice to to {@link #parseString(char[],int,int)}.
*
* @param cSeq Character sequence to parse.
* @throws IOException If there is an exception reading the
* characters.
*/
public void parseString(CharSequence cSeq) throws IOException {
char[] cs = Strings.toCharArray(cSeq);
parseString(cs,0,cs.length);
}
/**
* Parse the specified input source, passing extracted events to
* the handler. Concrete subclasses must implement this method.
*
* @param in Input source from which to read.
* @throws IOException If there is an exception reading from the
* specified stream.
*/
abstract public void parse(InputSource in) throws IOException;
/**
* Parse the specified character slice as a string input. Extracted
* content is passed to the current handler.
*
* @param cs Characters underlying slice.
* @param start Index of first character in slice.
* @param end One past the index of the last character in slice.
* @throws IOException If there is an exception reading the
* characters.
*/
abstract public void parseString(char[] cs, int start, int end)
throws IOException;
}