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package com.fasterxml.jackson.core.io;
import java.io.*;
/**
* Simple {@link InputStream} implementation that is used to "unwind" some
* data previously read from an input stream; so that as long as some of
* that data remains, it's returned; but as long as it's read, we'll
* just use data from the underlying original stream.
* This is similar to {@link java.io.PushbackInputStream}, but here there's
* only one implicit pushback, when instance is constructed.
*/
public final class MergedStream extends InputStream
{
final private IOContext _ctxt;
final private InputStream _in;
private byte[] _b;
private int _ptr;
final private int _end;
public MergedStream(IOContext ctxt, InputStream in, byte[] buf, int start, int end) {
_ctxt = ctxt;
_in = in;
_b = buf;
_ptr = start;
_end = end;
}
@Override
public int available() throws IOException {
if (_b != null) {
return _end - _ptr;
}
return _in.available();
}
@Override public void close() throws IOException {
_free();
_in.close();
}
@Override public void mark(int readlimit) {
if (_b == null) { _in.mark(readlimit); }
}
@Override public boolean markSupported() {
// Only supports marks past the initial rewindable section...
return (_b == null) && _in.markSupported();
}
@Override public int read() throws IOException {
if (_b != null) {
int c = _b[_ptr++] & 0xFF;
if (_ptr >= _end) {
_free();
}
return c;
}
return _in.read();
}
@Override public int read(byte[] b) throws IOException {
return read(b, 0, b.length);
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
if (_b != null) {
int avail = _end - _ptr;
if (len > avail) {
len = avail;
}
System.arraycopy(_b, _ptr, b, off, len);
_ptr += len;
if (_ptr >= _end) {
_free();
}
return len;
}
return _in.read(b, off, len);
}
@Override
public void reset() throws IOException {
if (_b == null) { _in.reset(); }
}
@Override
public long skip(long n) throws IOException {
long count = 0L;
if (_b != null) {
int amount = _end - _ptr;
if (amount > n) { // all in pushed back segment?
_ptr += (int) n;
return n;
}
_free();
count += amount;
n -= amount;
}
if (n > 0) { count += _in.skip(n); }
return count;
}
private void _free() {
byte[] buf = _b;
if (buf != null) {
_b = null;
if (_ctxt != null) {
_ctxt.releaseReadIOBuffer(buf);
}
}
}
}