/// <summary>

/// BytesIO([initializer]) -> object

///

/// Create a buffered I/O implementation using an in-memory bytes

/// buffer, ready for reading and writing.

/// </summary>

[PythonType, DontMapIDisposableToContextManager]

public class BytesIO : _BufferedIOBase, IEnumerator, IDisposable, IDynamicMetaObjectProvider {

#region Fields and constructors

private static readonly int DEFAULT_BUF_SIZE = 20;

private byte[] _data;

private int _pos, _length;

internal BytesIO(CodeContext/*!*/ context)

: base(context) {

}

public BytesIO(CodeContext/*!*/ context, object initial_bytes=null)

: base(context) {

}

public void __init__(object initial_bytes=null) {

if (Object.ReferenceEquals(_data, null)) {

_data = new byte[DEFAULT_BUF_SIZE];

}

_pos = _length = 0;

if (initial_bytes != null) {

DoWrite(initial_bytes);

_pos = 0;

}

}

#endregion

#region Public API

/// <summary>

/// close() -> None. Disable all I/O operations.

/// </summary>

public override void close(CodeContext/*!*/ context) {

_data = null;

}

/// <summary>

/// True if the file is closed.

/// </summary>

public override bool closed {

get {

return _data == null;

}

}

/// <summary>

/// getvalue() -> bytes.

///

/// Retrieve the entire contents of the BytesIO object.

/// </summary>

public Bytes getvalue() {

_checkClosed();

if (_length == 0) {

return Bytes.Empty;

}

byte[] arr = new byte[_length];

Array.Copy(_data, arr, _length);

return Bytes.Make(arr);

}

public MemoryView getbuffer() {

_checkClosed();

return new MemoryView(new Bytes(_data), 0, _length, 1, "B", PythonOps.MakeTuple(_length));

}

[Documentation("isatty() -> False\n\n"

+ "Always returns False since BytesIO objects are not connected\n"

+ "to a TTY-like device."

)]

public override bool isatty(CodeContext/*!*/ context) {

_checkClosed();

return false;

}

[Documentation("read([size]) -> read at most size bytes, returned as a bytes object.\n\n"

+ "If the size argument is negative, read until EOF is reached.\n"

+ "Return an empty string at EOF."

)]

public override object read(CodeContext/*!*/ context, object size=null) {

_checkClosed();

int sz = GetInt(size, -1);

int len = Math.Max(0, _length - _pos);

if (sz >= 0) {

len = Math.Min(len, sz);

}

if (len == 0) {

return Bytes.Empty;

}

byte[] arr = new byte[len];

Array.Copy(_data, _pos, arr, 0, len);

_pos += len;

return Bytes.Make(arr);

}

[Documentation("read1(size) -> read at most size bytes, returned as a bytes object.\n\n"

+ "If the size argument is negative or omitted, read until EOF is reached.\n"

+ "Return an empty string at EOF."

)]

public override Bytes read1(CodeContext/*!*/ context, int size) {

return (Bytes)read(context, size);

}

public override bool readable(CodeContext/*!*/ context) {

return true;

}

[Documentation("readinto(array_or_bytearray) -> int. Read up to len(b) bytes into b.\n\n"

+ "Returns number of bytes read (0 for EOF)."

)]

public BigInteger readinto([NotNull]ByteArray buffer) {

_checkClosed();

int len = Math.Min(_length - _pos, buffer.Count);

for (int i = 0; i < len; i++) {

buffer[i] = _data[_pos++];

}

return len;

}

public BigInteger readinto([NotNull]ArrayModule.array buffer) {

_checkClosed();

int len = Math.Min(_length - _pos, buffer.__len__() * buffer.itemsize);

int tailLen = len % buffer.itemsize;

buffer.FromStream(new MemoryStream(_data, _pos, len - tailLen, false, false), 0);

_pos += len - tailLen;

if (tailLen != 0) {

byte[] tail = buffer.RawGetItem(len / buffer.itemsize);

for (int i = 0; i < tailLen; i++) {

tail[i] = _data[_pos++];

}

buffer.FromStream(new MemoryStream(tail), len / buffer.itemsize);

}

return len;

}

public override BigInteger readinto(CodeContext/*!*/ context, object buf) {

if (buf is ByteArray bytes) {

return readinto(bytes);

}

if (buf is ArrayModule.array array) {

return readinto(array);

}

_checkClosed();

throw PythonOps.TypeError("must be read-write buffer, not {0}", PythonTypeOps.GetName(buf));

}

[Documentation("readline([size]) -> next line from the file, as bytes.\n\n"

+ "Retain newline. A non-negative size argument limits the maximum\n"

+ "number of bytes to return (an incomplete line may be returned then).\n"

+ "Return an empty string at EOF."

)]

public override object readline(CodeContext/*!*/ context, int limit=-1) {

return readline(limit);

}

private Bytes readline(int size=-1) {

_checkClosed();

if (_pos >= _length || size == 0) {

return Bytes.Empty;

}

int origPos = _pos;

while ((size < 0 || _pos - origPos < size) && _pos < _length) {

if (_data[_pos] == '\n') {

_pos++;

break;

}

_pos++;

}

byte[] arr = new byte[_pos - origPos];

Array.Copy(_data, origPos, arr, 0, _pos - origPos);

return Bytes.Make(arr);

}

public Bytes readline(object size) {

if (size == null) {

return readline(-1);

}

_checkClosed();

throw PythonOps.TypeError("integer argument expected, got '{0}'", PythonTypeOps.GetName(size));

}

[Documentation("readlines([size]) -> list of bytes objects, each a line from the file.\n\n"

+ "Call readline() repeatedly and return a list of the lines so read.\n"

+ "The optional size argument, if given, is an approximate bound on the\n"

+ "total number of bytes in the lines returned."

)]

public override PythonList readlines(object hint=null) {

_checkClosed();

int size = GetInt(hint, -1);

PythonList lines = new PythonList();

for (Bytes line = readline(-1); line.Count > 0; line = readline(-1)) {

lines.append(line);

if (size > 0) {

size -= line.Count;

if (size <= 0) {

break;

}

}

}

return lines;

}

private BigInteger seek(int pos, int whence) {

_checkClosed();

switch (whence) {

case 0:

if (pos < 0) {

throw PythonOps.ValueError("negative seek value {0}", pos);

}

_pos = pos;

return _pos;

case 1:

_pos = Math.Max(0, _pos + pos);

return _pos;

case 2:

_pos = Math.Max(0, _length + pos);

return _pos;

default:

throw PythonOps.ValueError("invalid whence ({0}, should be 0, 1 or 2)", whence);

}

}

public BigInteger seek(double pos, [Optional]object whence) => throw PythonOps.TypeError("integer argument expected, got float");

[Documentation("seek(pos, whence=0) -> int. Change stream position.\n\n"

+ "Seek to byte offset pos relative to position indicated by whence:\n"

+ " 0 Start of stream (the default). pos should be >= 0;\n"

+ " 1 Current position - pos may be negative;\n"

+ " 2 End of stream - pos usually negative.\n"

+ "Returns the new absolute position."

)]

public override BigInteger seek(CodeContext/*!*/ context, BigInteger pos, [Optional]object whence) {

_checkClosed();

int posInt = (int)pos;

switch (whence) {

case int v:

return seek(posInt, v);

case Extensible<int> v:

return seek(posInt, v);

case BigInteger v:

return seek(posInt, (int)v);

case Extensible<BigInteger> v:

return seek(posInt, (int)v.Value);

case double _:

case Extensible<double> _:

throw PythonOps.TypeError("integer argument expected, got float");

default:

return seek(posInt, GetInt(whence));

}

}

public override bool seekable(CodeContext/*!*/ context) {

return true;

}

[Documentation("tell() -> current file position, an integer")]

public override BigInteger tell(CodeContext/*!*/ context) {

_checkClosed();

return _pos;

}

[Documentation("truncate([size]) -> int. Truncate the file to at most size bytes.\n\n"

+ "Size defaults to the current file position, as returned by tell().\n"

+ "Returns the new size. Imply an absolute seek to the position size."

)]

public BigInteger truncate() {

return truncate(_pos);

}

public BigInteger truncate(int size) {

_checkClosed();

if (size < 0) {

throw PythonOps.ValueError("negative size value {0}", size);

}

_length = Math.Min(_length, size);

return (BigInteger)size;

}

public override BigInteger truncate(CodeContext/*!*/ context, object size=null) {

if (size == null) {

return truncate();

}

int sizeInt;

if (TryGetInt(size, out sizeInt)) {

return truncate(sizeInt);

}

_checkClosed();

throw PythonOps.TypeError("integer argument expected, got '{0}'", PythonTypeOps.GetName(size));

}

public override bool writable(CodeContext/*!*/ context) {

return true;

}

[Documentation("write(bytes) -> int. Write bytes to file.\n\n"

+ "Return the number of bytes written."

)]

public override BigInteger write(CodeContext/*!*/ context, object bytes) {

_checkClosed();

return DoWrite(bytes);

}

[Documentation("writelines(sequence_of_strings) -> None. Write strings to the file.\n\n"

+ "Note that newlines are not added. The sequence can be any iterable\n"

+ "object producing strings. This is equivalent to calling write() for\n"

+ "each string."

)]

public void writelines([NotNull]IEnumerable lines) {

_checkClosed();

IEnumerator en = lines.GetEnumerator();

while (en.MoveNext()) {

DoWrite(en.Current);

}

}

#endregion

#region IDisposable methods

void IDisposable.Dispose() { }

#endregion

#region IEnumerator methods

private object _current = null;

object IEnumerator.Current {

get {

_checkClosed();

return _current;

}

}

bool IEnumerator.MoveNext() {

Bytes line = readline(-1);

if (line.Count == 0) {

return false;

}

_current = line;

return true;

}

void IEnumerator.Reset() {

seek(0, 0);

_current = null;

}

#endregion

#region IDynamicMetaObjectProvider Members

DynamicMetaObject IDynamicMetaObjectProvider.GetMetaObject(Expression parameter) {

return new MetaExpandable<BytesIO>(parameter, this);

}

#endregion

#region Private implementation details

private int DoWrite(byte[] bytes) {

if (bytes.Length == 0) {

return 0;

}

EnsureSizeSetLength(_pos + bytes.Length);

Array.Copy(bytes, 0, _data, _pos, bytes.Length);

_pos += bytes.Length;

return bytes.Length;

}

private int DoWrite(ICollection<byte> bytes) {

int nbytes = bytes.Count;

if (nbytes == 0) {

return 0;

}

EnsureSizeSetLength(_pos + nbytes);

bytes.CopyTo(_data, _pos);

_pos += nbytes;

return nbytes;

}

private int DoWrite(string bytes) {

// CLR strings are natively Unicode (UTF-16 LE, to be precise).

// In 2.x, io.BytesIO.write() takes "bytes or bytearray" as a parameter.

// On 2.x "bytes" is an alias for str, so str types are accepted by BytesIO.write().

// When given a unicode object, 2.x BytesIO.write() complains:

// TypeError: 'unicode' does not have the buffer interface

// We will accept CLR strings, but only if the data in it is in Latin 1 (iso-8859-1)

// encoding (i.e. ord(c) for all c is within 0-255.

// Alternatively, we could support strings containing any Unicode character by ignoring

// any 0x00 bytes, but as CPython doesn't support that it is unlikely that we will need to.

int nbytes = bytes.Length;

if (nbytes == 0) {

return 0;

}

byte[] _raw_string = new byte[nbytes];

for (int i = 0; i < nbytes; i++) {

int ord = (int)bytes[i];

if(ord < 256) {

_raw_string[i] = (byte)ord;

} else {

// A character outside the range 0x00-0xFF is present in the original string.

// Ejecting, emulating the cPython 2.x behavior when it enounters "unicode".

// This should keep the unittest gods at bay.

throw PythonOps.TypeError("'unicode' does not have the buffer interface");

}

}

return DoWrite(_raw_string);

}

private int DoWrite(object bytes) {

switch (bytes) {

case byte[] b:

return DoWrite(b);

case Bytes b:

return DoWrite(b.UnsafeByteArray);

case ArrayModule.array a:

return DoWrite(a.ToByteArray()); // as byte[]

case ICollection<byte> c:

return DoWrite(c);

case string s:

// TODO Remove this when we move to 3.x

return DoWrite(s);

case MemoryView mv:

return DoWrite(mv.tobytes().UnsafeByteArray);

}

throw PythonOps.TypeError("expected a readable buffer object");

}

private void EnsureSize(int size) {

Debug.Assert(size > 0);

if (_data.Length < size) {

size = size <= DEFAULT_BUF_SIZE ? DEFAULT_BUF_SIZE : Math.Max(size, _data.Length * 2);

byte[] oldBuffer = _data;

_data = new byte[size];

Array.Copy(oldBuffer, _data, _length);

}

}

private void EnsureSizeSetLength(int size) {

Debug.Assert(size >= _pos);

Debug.Assert(_length <= _data.Length);

if (_data.Length < size) {

// EnsureSize is guaranteed to resize, so we need not write any zeros here.

EnsureSize(size);

_length = size;

return;

}

// _data[_pos:size] is about to be overwritten, so we only need to zero out _data[_length:_pos]

while (_length < _pos) {

_data[_length++] = 0;

}

_length = Math.Max(_length, size);

}

#endregion

}