/*

Unicode implementation based on original code by Fredrik Lundh,

modified by Marc-Andre Lemburg <mal@lemburg.com>.

Major speed upgrades to the method implementations at the Reykjavik

NeedForSpeed sprint, by Fredrik Lundh and Andrew Dalke.

Copyright (c) Corporation for National Research Initiatives.

--------------------------------------------------------------------

The original string type implementation is:

  Copyright (c) 1999 by Secret Labs AB

  Copyright (c) 1999 by Fredrik Lundh

By obtaining, using, and/or copying this software and/or its

associated documentation, you agree that you have read, understood,

and will comply with the following terms and conditions:

Permission to use, copy, modify, and distribute this software and its

associated documentation for any purpose and without fee is hereby

granted, provided that the above copyright notice appears in all

copies, and that both that copyright notice and this permission notice

appear in supporting documentation, and that the name of Secret Labs

AB or the author not be used in advertising or publicity pertaining to

distribution of the software without specific, written prior

permission.

SECRET LABS AB AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO

THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND

FITNESS.  IN NO EVENT SHALL SECRET LABS AB OR THE AUTHOR BE LIABLE FOR

ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN

ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT

OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

--------------------------------------------------------------------

*/

#include "Python.h"

#include "pycore_freelist.h"      // _Py_FREELIST_FREE()

#include "pycore_long.h"          // _PyLong_FormatWriter()

#include "pycore_unicodeobject.h" // _PyUnicode_Result()

#ifdef MS_WINDOWS

   /* On Windows, overallocate by 50% is the best factor */

#  define OVERALLOCATE_FACTOR 2

#else

   /* On Linux, overallocate by 25% is the best factor */

#  define OVERALLOCATE_FACTOR 4

#endif

/* Compilation of templated routines */

#define STRINGLIB_GET_EMPTY() _PyUnicode_GetEmpty()

#include "stringlib/ucs1lib.h"

#include "stringlib/find_max_char.h"

#include "stringlib/undef.h"

void

_PyUnicodeWriter_Init(_PyUnicodeWriter *writer)

{

    memset(writer, 0, sizeof(*writer));

    /* ASCII is the bare minimum */

    writer->min_char = 127;

    /* use a kind value smaller than PyUnicode_1BYTE_KIND so

       _PyUnicodeWriter_PrepareKind() will copy the buffer. */

    assert(writer->kind == 0);

    assert(writer->kind < PyUnicode_1BYTE_KIND);

}

PyUnicodeWriter*

PyUnicodeWriter_Create(Py_ssize_t length)

{

    if (length < 0) {

        PyErr_SetString(PyExc_ValueError,

                        "length must be positive");

        return NULL;

    }

    const size_t size = sizeof(_PyUnicodeWriter);

    PyUnicodeWriter *pub_writer;

    pub_writer = _Py_FREELIST_POP_MEM(unicode_writers);

    if (pub_writer == NULL) {

        pub_writer = (PyUnicodeWriter *)PyMem_Malloc(size);

        if (pub_writer == NULL) {

            return (PyUnicodeWriter *)PyErr_NoMemory();

        }

    }

    _PyUnicodeWriter *writer = (_PyUnicodeWriter *)pub_writer;

    _PyUnicodeWriter_Init(writer);

    // The buffer is created lazily at the first write, except if

    // the read-only optimization is used.

    writer->min_length = length;

    writer->overallocate = 1;

    return pub_writer;

}

void

PyUnicodeWriter_Discard(PyUnicodeWriter *writer)

{

    if (writer == NULL) {

        return;

    }

    _PyUnicodeWriter_Dealloc((_PyUnicodeWriter*)writer);

    _Py_FREELIST_FREE(unicode_writers, writer, PyMem_Free);

}

// Initialize _PyUnicodeWriter with initial buffer

void

_PyUnicodeWriter_InitWithBuffer(_PyUnicodeWriter *writer, PyObject *buffer)

{

    assert(PyUnstable_Object_IsUniquelyReferenced(buffer));

    memset(writer, 0, sizeof(*writer));

    _PyUnicodeWriter_SetBuffer(writer, buffer);

    writer->min_length = writer->size;

    assert(_PyUnicodeWriter_CanWrite(writer));

}

int

_PyUnicodeWriter_PrepareInternal(_PyUnicodeWriter *writer,

                                 Py_ssize_t length, Py_UCS4 maxchar)

{

    assert(length >= 0);

    assert(maxchar <= _Py_MAX_UNICODE);

    // Check that _PyUnicodeWriter_Prepare() or _PyUnicodeWriter_PrepareKind()

    // was used

    assert(maxchar > writer->maxchar

           || (length > (writer->size - writer->pos) && length >= 1));

    if (length > PY_SSIZE_T_MAX - writer->pos) {

        PyErr_NoMemory();

        return -1;

    }

    Py_ssize_t alloc = writer->pos + length;

    maxchar = Py_MAX(maxchar, writer->min_char);

    PyObject *new_buffer;

    if (writer->buffer == NULL) {

        assert(!writer->readonly);

        // Do not overallocate at the first allocation, but use min_length

        if (alloc < writer->min_length) {

            alloc = writer->min_length;

        }

        new_buffer = PyUnicode_New(alloc, maxchar);

        if (new_buffer == NULL) {

            return -1;

        }

    }

    else if (alloc > writer->size) {

        // Do not overallocate at the first allocation, but use min_length

        int overallocate = (writer->overallocate && !writer->readonly);

        if (overallocate

            && alloc <= (PY_SSIZE_T_MAX - alloc / OVERALLOCATE_FACTOR)) {

            /* overallocate to limit the number of realloc() */

            alloc += alloc / OVERALLOCATE_FACTOR;

        }

        if (alloc < writer->min_length) {

            alloc = writer->min_length;

        }

        if (maxchar > writer->maxchar || writer->readonly) {

            /* resize + widen */

            maxchar = Py_MAX(maxchar, writer->maxchar);

            new_buffer = PyUnicode_New(alloc, maxchar);

            if (new_buffer == NULL) {

                return -1;

            }

            _PyUnicode_FastCopyCharacters(new_buffer, 0,

                                          writer->buffer, 0, writer->pos);

        }

        else {

            new_buffer = _PyUnicode_ResizeCompact(writer->buffer, alloc);

            if (new_buffer == NULL) {

                return -1;

            }

            // Do not DECREF the old buffer

            writer->buffer = NULL;

        }

    }

    else {

        assert(maxchar > writer->maxchar);

        assert(!writer->readonly);

        new_buffer = PyUnicode_New(writer->size, maxchar);

        if (new_buffer == NULL) {

            return -1;

        }

        _PyUnicode_FastCopyCharacters(new_buffer, 0,

                                      writer->buffer, 0, writer->pos);

    }

    _PyUnicodeWriter_SetBuffer(writer, new_buffer);

    return 0;

#undef OVERALLOCATE_FACTOR

}

int

_PyUnicodeWriter_PrepareKindInternal(_PyUnicodeWriter *writer,

                                     int kind)

{

    Py_UCS4 maxchar;

    /* ensure that the _PyUnicodeWriter_PrepareKind macro was used */

    assert(writer->kind < kind);

    switch (kind)

    {

    case PyUnicode_1BYTE_KIND: maxchar = 0xff; break;

    case PyUnicode_2BYTE_KIND: maxchar = 0xffff; break;

    case PyUnicode_4BYTE_KIND: maxchar = _Py_MAX_UNICODE; break;

    default:

        Py_UNREACHABLE();

    }

    return _PyUnicodeWriter_PrepareInternal(writer, 0, maxchar);

}

int

_PyUnicodeWriter_WriteChar(_PyUnicodeWriter *writer, Py_UCS4 ch)

{

    return _PyUnicodeWriter_WriteCharInline(writer, ch);

}

int

PyUnicodeWriter_WriteChar(PyUnicodeWriter *writer, Py_UCS4 ch)

{

    if (ch > _Py_MAX_UNICODE) {

        PyErr_SetString(PyExc_ValueError,

                        "character must be in range(0x110000)");

        return -1;

    }

    return _PyUnicodeWriter_WriteChar((_PyUnicodeWriter*)writer, ch);

}

int

_PyUnicodeWriter_WriteStr(_PyUnicodeWriter *writer, PyObject *str)

{

    assert(PyUnicode_Check(str));

    Py_ssize_t len = PyUnicode_GET_LENGTH(str);

    if (len == 0) {

        return 0;

    }

    Py_UCS4 maxchar = PyUnicode_MAX_CHAR_VALUE(str);

    if (maxchar > writer->maxchar || len > writer->size - writer->pos) {

        if (writer->buffer == NULL && PyUnicode_CheckExact(str)) {

            assert(_PyUnicode_CheckConsistency(str, 1));

            _PyUnicodeWriter_SetReadOnly(writer, Py_NewRef(str), len);

            return 0;

        }

        if (_PyUnicodeWriter_PrepareInternal(writer, len, maxchar) == -1)

            return -1;

    }

    assert(_PyUnicodeWriter_CanWrite(writer));

    _PyUnicode_FastCopyCharacters(writer->buffer, writer->pos,

                                  str, 0, len);

    writer->pos += len;

    return 0;

}

int

PyUnicodeWriter_WriteStr(PyUnicodeWriter *pub_writer, PyObject *obj)

{

    _PyUnicodeWriter *writer = (_PyUnicodeWriter*)pub_writer;

    PyTypeObject *type = Py_TYPE(obj);

    if (type == &PyUnicode_Type) {

        return _PyUnicodeWriter_WriteStr(writer, obj);

    }

    if (type == &PyLong_Type) {

        return _PyLong_FormatWriter(writer, obj, 10, 0);

    }

    PyObject *str = PyObject_Str(obj);

    if (str == NULL) {

        return -1;

    }

    int res = _PyUnicodeWriter_WriteStr(writer, str);

    Py_DECREF(str);

    return res;

}

int

PyUnicodeWriter_WriteRepr(PyUnicodeWriter *pub_writer, PyObject *obj)

{

    _PyUnicodeWriter *writer = (_PyUnicodeWriter*)pub_writer;

    if (obj == NULL) {

        return _PyUnicodeWriter_WriteASCIIString(writer, "<NULL>", 6);

    }

    if (Py_TYPE(obj) == &PyLong_Type) {

        return _PyLong_FormatWriter(writer, obj, 10, 0);

    }

    // Fast path for None; see gh-159813 for the rationale.

    if (obj == Py_None) {

        return _PyUnicodeWriter_WriteASCIIString(writer, "None", 4);

    }

    PyObject *repr = PyObject_Repr(obj);

    if (repr == NULL) {

        return -1;

    }

    int res = _PyUnicodeWriter_WriteStr(writer, repr);

    Py_DECREF(repr);

    return res;

}

int

_PyUnicodeWriter_WriteSubstring(_PyUnicodeWriter *writer, PyObject *str,

                                Py_ssize_t start, Py_ssize_t end)

{

    assert(0 <= start);

    assert(start <= end);

    assert(end <= PyUnicode_GET_LENGTH(str));

    if (start == 0 && end == PyUnicode_GET_LENGTH(str)) {

        return _PyUnicodeWriter_WriteStr(writer, str);

    }

    Py_ssize_t len = end - start;

    if (len == 0) {

        return 0;

    }

    Py_UCS4 maxchar;

    if (PyUnicode_MAX_CHAR_VALUE(str) > writer->maxchar) {

        maxchar = _PyUnicode_FindMaxChar(str, start, end);

    }

    else {

        maxchar = writer->maxchar;

    }

    if (_PyUnicodeWriter_Prepare(writer, len, maxchar) < 0) {

        return -1;

    }

    assert(_PyUnicodeWriter_CanWrite(writer));

    _PyUnicode_FastCopyCharacters(writer->buffer, writer->pos,

                                  str, start, len);

    writer->pos += len;

    return 0;

}

int

PyUnicodeWriter_WriteSubstring(PyUnicodeWriter *writer, PyObject *str,

                               Py_ssize_t start, Py_ssize_t end)

{

    if (!PyUnicode_Check(str)) {

        PyErr_Format(PyExc_TypeError, "expect str, not %T", str);

        return -1;

    }

    if (start < 0 || start > end) {

        PyErr_Format(PyExc_ValueError, "invalid start argument");

        return -1;

    }

    if (end > PyUnicode_GET_LENGTH(str)) {

        PyErr_Format(PyExc_ValueError, "invalid end argument");

        return -1;

    }

    return _PyUnicodeWriter_WriteSubstring((_PyUnicodeWriter*)writer, str,

                                           start, end);

}

int

_PyUnicodeWriter_WriteASCIIString(_PyUnicodeWriter *writer,

                                  const char *ascii, Py_ssize_t len)

{

    if (len == -1)

        len = strlen(ascii);

    if (len == 0) {

        return 0;

    }

    assert(ucs1lib_find_max_char((const Py_UCS1*)ascii, (const Py_UCS1*)ascii + len) <= 127);

    if (_PyUnicodeWriter_Prepare(writer, len, 127) == -1) {

        return -1;

    }

    assert(_PyUnicodeWriter_CanWrite(writer));

    switch (writer->kind)

    {

    case PyUnicode_1BYTE_KIND:

    {

        const Py_UCS1 *str = (const Py_UCS1 *)ascii;

        Py_UCS1 *data = writer->data;

        memcpy(data + writer->pos, str, len);

        break;

    }

    case PyUnicode_2BYTE_KIND:

    {

        _PyUnicode_CONVERT_BYTES(

            Py_UCS1, Py_UCS2,

            ascii, ascii + len,

            (Py_UCS2 *)writer->data + writer->pos);

        break;

    }

    case PyUnicode_4BYTE_KIND:

    {

        _PyUnicode_CONVERT_BYTES(

            Py_UCS1, Py_UCS4,

            ascii, ascii + len,

            (Py_UCS4 *)writer->data + writer->pos);

        break;

    }

    default:

        Py_UNREACHABLE();

    }

    writer->pos += len;

    return 0;

}

int

PyUnicodeWriter_WriteASCII(PyUnicodeWriter *writer,

                           const char *str,

                           Py_ssize_t size)

{

    assert(writer != NULL);

    _Py_AssertHoldsTstate();

    return _PyUnicodeWriter_WriteASCIIString((_PyUnicodeWriter*)writer, str, size);

}

int

PyUnicodeWriter_WriteUTF8(PyUnicodeWriter *writer,

                          const char *str,

                          Py_ssize_t size)

{

    if (size < 0) {

        size = strlen(str);

    }

    return _PyUnicode_DecodeUTF8Writer((_PyUnicodeWriter*)writer, str, size,

                                       _Py_ERROR_STRICT, NULL, NULL);

}

int

PyUnicodeWriter_DecodeUTF8Stateful(PyUnicodeWriter *writer,

                                   const char *str,

                                   Py_ssize_t size,

                                   const char *errors,

                                   Py_ssize_t *consumed)

{

    if (size < 0) {

        size = strlen(str);

    }

    return _PyUnicode_DecodeUTF8Writer((_PyUnicodeWriter*)writer, str, size,

                                       _Py_ERROR_UNKNOWN, errors,

                                       consumed);

}

int

_PyUnicodeWriter_WriteLatin1String(_PyUnicodeWriter *writer,

                                   const char *str, Py_ssize_t len)

{

    if (len == 0) {

        return 0;

    }

    const Py_UCS1 *ucs1 = (const Py_UCS1 *)str;

    Py_UCS4 maxchar = ucs1lib_find_max_char(ucs1, ucs1 + len);

    if (_PyUnicodeWriter_Prepare(writer, len, maxchar) < 0) {

        return -1;

    }

    assert(_PyUnicodeWriter_CanWrite(writer));

    Py_ssize_t index = writer->pos;

    switch (writer->kind) {

    case PyUnicode_1BYTE_KIND: {

        memcpy((Py_UCS1 *)writer->data + index, ucs1, len);

        break;

    }

    case PyUnicode_2BYTE_KIND: {

        Py_UCS2 *ucs2 = (Py_UCS2 *)writer->data + index;

        const Py_UCS1 *end = ucs1 + len;

        for (; ucs1 < end; ++ucs2, ++ucs1) {

            *ucs2 = (Py_UCS2)*ucs1;

        }

        break;

    }

    case PyUnicode_4BYTE_KIND: {

        Py_UCS4 *ucs4 = (Py_UCS4 *)writer->data + index;

        const Py_UCS1 *end = ucs1 + len;

        for (; ucs1 < end; ++ucs4, ++ucs1) {

            *ucs4 = (Py_UCS4)*ucs1;

        }

        break;

    }

    default:

        Py_UNREACHABLE();

    }

    writer->pos += len;

    return 0;

}

PyObject *

_PyUnicodeWriter_Finish(_PyUnicodeWriter *writer)

{

#ifdef Py_DEBUG

    // Check for buffer overflow

    if (writer->buffer != NULL) {

        Py_ssize_t pos = PyUnicode_GET_LENGTH(writer->buffer);

        Py_UCS4 ch = PyUnicode_READ_CHAR(writer->buffer, pos);

        if (ch != 0) {

            _Py_FatalErrorFormat(__func__,

                                 "Buffer overflow detected in "

                                 "PyUnicodeWriter %p at position %zd",

                                 writer, pos);

        }

    }

#endif

    PyObject *str = writer->buffer;

    writer->buffer = NULL;

    Py_ssize_t final_size = writer->pos;

    if (final_size == 0) {

        // Get the empty string singleton

        PyObject *empty = _PyUnicode_GetEmpty();

        Py_XDECREF(str);  // writer->buffer can be NULL if the position is 0

        return empty;

    }

    if (writer->readonly) {

        assert(final_size == PyUnicode_GET_LENGTH(str));

        goto done;

    }

    assert(final_size <= PyUnicode_GET_LENGTH(str));

    if (final_size == 1 && PyUnicode_KIND(str) == PyUnicode_1BYTE_KIND) {

        // Get the single character singleton

        assert(PyUnicode_GET_LENGTH(str) >= 1);

        const Py_UCS1 *data = PyUnicode_1BYTE_DATA(str);

        Py_UCS1 ch = data[0];

        Py_DECREF(str);

        str = _Py_LATIN1_CHR(ch);

        goto done;

    }

    if (writer->recheck_maxchar) {

        Py_UCS4 maxchar = _PyUnicode_FindMaxChar(str, 0, final_size);

        if (maxchar != writer->maxchar) {

            // Adjust the string kind

            PyObject *str2 = PyUnicode_New(final_size, maxchar);

            if (str2 == NULL) {

                Py_DECREF(str);

                return NULL;

            }

            _PyUnicode_FastCopyCharacters(str2, 0, str, 0, final_size);

            Py_SETREF(str, str2);

            goto done;

        }

    }

    if (PyUnicode_GET_LENGTH(str) != final_size) {

        // Truncate the string

        PyObject *str2 = _PyUnicode_ResizeCompact(str, final_size);

        if (str2 == NULL) {

            Py_DECREF(str);

            return NULL;

        }

        str = str2;

        goto done;

    }

done:

    assert(_PyUnicode_CheckConsistency(str, 1));

    return str;

}

PyObject *

_PyUnicodeWriter_FinishWithSize(_PyUnicodeWriter *writer, Py_ssize_t size)

{

    assert(0 <= size);

    if (writer->buffer != NULL) {

        assert(size <= writer->pos);

        assert(size <= PyUnicode_GET_LENGTH(writer->buffer));

        if (size < writer->pos) {

            // Truncate the string: we may need to adjust the string kind

            writer->recheck_maxchar = 1;

        }

    }

    else {

        assert(size == 0);

    }

    writer->pos = size;

    return _PyUnicodeWriter_Finish(writer);

}

PyObject*

PyUnicodeWriter_Finish(PyUnicodeWriter *writer)

{

    PyObject *str = _PyUnicodeWriter_Finish((_PyUnicodeWriter*)writer);

    assert(((_PyUnicodeWriter*)writer)->buffer == NULL);

    _Py_FREELIST_FREE(unicode_writers, writer, PyMem_Free);

    return str;

}

void

_PyUnicodeWriter_Dealloc(_PyUnicodeWriter *writer)

{

    Py_CLEAR(writer->buffer);

}