package com.fasterxml.jackson.core.format;
import java.io.*;
import com.fasterxml.jackson.core.JsonFactory;
/**
* Interface used to expose beginning of a data file to data format
* detection code.
*/
public interface InputAccessor
{
/**
* Method to call to check if more input is available.
* Since this may result in more content to be read (at least
* one more byte), a {@link IOException} may get thrown.
*/
public boolean hasMoreBytes() throws IOException;
/**
* Returns next byte available, if any; if no more bytes are
* available, will throw {@link java.io.EOFException}.
*/
public byte nextByte() throws IOException;
/**
* Method that can be called to reset accessor to read from beginning
* of input.
*/
public void reset();
/*
/**********************************************************
/* Standard implementation
/**********************************************************
*/
/**
* Basic implementation that reads data from given
* {@link InputStream} and buffers it as necessary.
*/
public class Std implements InputAccessor
{
protected final InputStream _in;
protected final byte[] _buffer;
/**
* Number of bytes in {@link #_buffer} that are valid
* buffered content.
*/
protected int _bufferedAmount;
/**
* Pointer to next available buffered byte in {@link #_buffer}.
*/
protected int _ptr;
/**
* Constructor used when content to check is available via
* input stream and must be read.
*/
public Std(InputStream in, byte[] buffer)
{
_in = in;
_buffer = buffer;
_bufferedAmount = 0;
}
/**
* Constructor used when the full input (or at least enough leading bytes
* of full input) is available.
*/
public Std(byte[] inputDocument)
{
_in = null;
_buffer = inputDocument;
// we have it all:
_bufferedAmount = inputDocument.length;
}
// @Override
public boolean hasMoreBytes() throws IOException
{
if (_ptr < _bufferedAmount) { // already got more
return true;
}
int amount = _buffer.length - _ptr;
if (amount < 1) { // can not load any more
return false;
}
int count = _in.read(_buffer, _ptr, amount);
if (count <= 0) { // EOF
return false;
}
_bufferedAmount += count;
return true;
}
// @Override
public byte nextByte() throws IOException
{
// should we just try loading more automatically?
if (_ptr >- _bufferedAmount) {
if (!hasMoreBytes()) {
throw new EOFException("Could not read more than "+_ptr+" bytes (max buffer size: "+_buffer.length+")");
}
}
return _buffer[_ptr++];
}
// @Override
public void reset() {
_ptr = 0;
}
/*
/**********************************************************
/* Extended API for DataFormatDetector/Matcher
/**********************************************************
*/
public DataFormatMatcher createMatcher(JsonFactory match, MatchStrength matchStrength)
{
return new DataFormatMatcher(_in, _buffer, _bufferedAmount, match, matchStrength);
}
}
}