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TDB is a storage subsystem for Jena and ARQ
/*
* (c) Copyright 2007, 2008, 2009 Hewlett-Packard Development Company, LP
* All rights reserved.
* [See end of file]
*/
package atlas.io;
import java.io.IOException ;
import java.io.InputStream ;
import java.io.Reader ;
import com.hp.hpl.jena.shared.JenaException ;
import com.hp.hpl.jena.util.FileUtils ;
/** Parsing-centric reader.
* Faster than using BufferedReader, sometimes a lot faster, when
* tokenizing is the critical performance point.
*
* Supports a line and column
* count. Initially, line = 1, col = 1. Columns go 1..N
*
* This class is not thread safe.
* @see BufferingWriter
*/
public abstract class PeekReader extends Reader
{
// Does buffering here instead of using a BufferedReader help?
// YES. A lot (Java6).
// Possibly because BufferedReader internally uses synchronized,
// even on getting a singe character. Thisis not only an unnecessary cost
// but also possibly because it stops the JIT doing a better job.
// **** read(char[]) is a loop of single char operations.
private static final int PUSHBACK_SIZE = 10 ;
static final byte CHAR0 = (char)0 ;
static final int EOF = -1 ;
static final int UNSET = -2 ;
private char[] pushbackChars ;
private int idxPushback ; // Index into pushbackChars: points to next pushBack. -1 => none.
private int currChar = UNSET ; // Next character to return when reading forwards.
private long posn ;
public static final int INIT_LINE = 1 ;
public static final int INIT_COL = 1 ;
private long colNum ;
private long lineNum ;
// ---- static construction methods.
public static PeekReader make(Reader r)
{
if ( r instanceof PeekReader )
return (PeekReader)r ;
// if ( r instanceof BufferedReader )
// Log.warn(PeekReader.class, "BufferedReader passed to PeekReader") ;
return new PeekReaderSource(r) ;
}
public static PeekReader make(Reader r, int bufferSize)
{
if ( r instanceof PeekReader )
return (PeekReader)r ;
return new PeekReaderSource(r, bufferSize) ;
}
public static PeekReader makeUTF8(InputStream in)
{
Reader r = FileUtils.asUTF8(in) ;
return make(r) ;
}
public static PeekReader make(String string)
{
return new PeekReaderCharSequence(string) ;
}
protected PeekReader()
{
this.pushbackChars = new char[PUSHBACK_SIZE] ;
this.idxPushback = -1 ;
this.colNum = INIT_COL ;
this.lineNum = INIT_LINE ;
this.posn = 0 ;
// We start at character "-1", i.e. just before the file starts.
// Advance always so that the peek character is valid (is character 0)
// Returns the character before the file starts (i.e. UNSET).
}
// public static PeekReader test(String x) { return new PeekReaderSource(new StringReader(x)) ; }
//
// // A bit slow in that it copies out of the string into the intermediate char array.
// // But happens in one block operations when less than buffer size.
// static PeekReader make(String x, int buffSize)
// { return new PeekReaderSource(new StringReader(x), buffSize) ; }
public long getLineNum() { return lineNum; }
public long getColNum() { return colNum; }
public long getPosition() { return posn; }
//---- Do not access currChar except with peekChar/setCurrChar.
public int peekChar()
{
if ( idxPushback >= 0 )
return pushbackChars[idxPushback] ;
// If not started ... delayed initialization.
if ( currChar == UNSET )
init() ;
return currChar ;
}
// And the correct way to read the currChar is to call peekChar.
private void setCurrChar(int ch)
{
currChar = ch ;
}
public int readChar() { return nextChar() ; }
/** push back a character : does not alter underlying position, line or column counts*/
public void pushbackChar(int ch) { unreadChar(ch) ; }
// Reader operations
@Override
public void close() throws IOException
{
closeInput() ;
}
@Override
public int read() throws IOException
{
if ( eof() )
return EOF ;
int x = readChar() ;
return x ;
}
@Override
public int read(char[] cbuf, int off, int len) throws IOException
{
if ( eof() )
return EOF ;
// Note - need to preserve line count, so single char ops are reasonably efficient.
for ( int i = 0 ; i < len ; i++ )
{
int ch = readChar() ;
if ( ch == EOF )
return (i==0)? EOF : i ;
cbuf[i+off] = (char)ch ;
}
return len ;
}
public final boolean eof() { return peekChar() == EOF ; }
//protected abstract void init() ;
protected abstract int advance() ;
protected abstract void closeInput() ;
// ----------------
// The methods below are the only ones to manipulate the character buffers.
// Other methods may read the state of variables.
private void unreadChar(int ch)
{
// The push back buffer is in the order where [0] is the oldest.
// Does not alter the line number, column number or position count.
if ( idxPushback >= pushbackChars.length )
{
// Enlarge pushback buffer.
char[] pushbackChars2 = new char[pushbackChars.length*2] ;
System.arraycopy(pushbackChars2, 0, pushbackChars2, 0, pushbackChars.length) ;
pushbackChars = pushbackChars2 ;
//throw new JenaException("Pushback buffer overflow") ;
}
if ( ch == EOF || ch == UNSET )
throw new JenaException("Illegal character to push back: "+ch) ;
idxPushback++ ;
pushbackChars[idxPushback] = (char)ch ;
}
private void init()
{
advanceAndSet() ;
if ( currChar == UNSET )
setCurrChar(EOF) ;
}
private void advanceAndSet()
{
int ch = advance() ;
setCurrChar(ch) ;
}
// /** Move forward one character and return it.
// * Ensure the buffer is not empty, or boolean eof is set
// */
// private int _advance()
// {
// if ( idx >= buffLen )
// // Points outsize the array. Refill it
// _fillArray() ;
//
// // Advance one character.
// if ( buffLen >= 0 )
// {
// char ch = chars[idx] ;
// // Advance the lookahead character
// idx++ ;
// return ch ;
// }
// else
// // Buffer empty, end of stream.
// return EOF ;
// }
//
// private int _fillArray()
// {
// int x = source.fill(chars) ;
// idx = 0 ;
// buffLen = x ; // Maybe -1
// return x ;
// }
// Invariants.
// currChar is either chars[idx-1] or pushbackChars[idxPushback]
/** Return the next character, moving on one place and resetting the peek character */
private int nextChar()
{
int ch = peekChar() ;
if ( ch == EOF )
return EOF ;
if ( idxPushback >= 0 )
{
ch = replayPushback() ;
return ch ;
}
posn++ ;
if (ch == '\n')
{
lineNum++;
colNum = INIT_COL ;
}
else
colNum++;
advanceAndSet() ;
return ch ;
}
private int replayPushback()
{
if ( idxPushback >=0 )
{
// Simple case : theer are more charcaters in the pushback buffer after this one.
char ch2 = pushbackChars[idxPushback] ;
idxPushback-- ;
return ch2 ;
}
throw new IllegalStateException() ;
// // Push back buffer empty.
// // Next char is from chars[] which must have yielded a
// // character and idx >= 1 or the stream was zero chars (idx <= 0)
// int nextCurrChar = EOF ;
//
// if ( idx-1 >= 0 )
// // Had been a read.
// nextCurrChar = chars[idx-1] ;
// setCurrChar(nextCurrChar) ;
}
}
/*
* (c) Copyright 2007, 2008, 2009 Hewlett-Packard Development Company, LP
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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