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// Copyright 2015-2016 Mozilla Foundation. See the COPYRIGHT
// file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#pragma once
#ifndef encoding_rs_cpp_h_
#define encoding_rs_cpp_h_
#include "gsl/gsl"
#include <memory>
#include <optional>
#include <string>
#include <string_view>
#include <tuple>
#include <vector>
namespace encoding_rs {
class Encoding;
class Decoder;
class Encoder;
}; // namespace encoding_rs
#define ENCODING_RS_ENCODING encoding_rs::Encoding
#define ENCODING_RS_NOT_NULL_CONST_ENCODING_PTR \
gsl::not_null<const encoding_rs::Encoding*>
#define ENCODING_RS_ENCODER encoding_rs::Encoder
#define ENCODING_RS_DECODER encoding_rs::Decoder
#include "encoding_rs.h"
namespace encoding_rs {
/**
* A converter that decodes a byte stream into Unicode according to a
* character encoding in a streaming (incremental) manner.
*
* The various `decode_*` methods take an input buffer (`src`) and an output
* buffer `dst` both of which are caller-allocated. There are variants for
* both UTF-8 and UTF-16 output buffers.
*
* A `decode_*` method decodes bytes from `src` into Unicode characters stored
* into `dst` until one of the following three things happens:
*
* 1. A malformed byte sequence is encountered (`*_without_replacement`
* variants only).
*
* 2. The output buffer has been filled so near capacity that the decoder
* cannot be sure that processing an additional byte of input wouldn't
* cause so much output that the output buffer would overflow.
*
* 3. All the input bytes have been processed.
*
* The `decode_*` method then returns tuple of a status indicating which one
* of the three reasons to return happened, how many input bytes were read,
* how many output code units (`uint8_t` when decoding into UTF-8 and `char16_t`
* when decoding to UTF-16) were written, and in the case of the
* variants performing replacement, a boolean indicating whether an error was
* replaced with the REPLACEMENT CHARACTER during the call.
*
* The number of bytes "written" is what's logically written. Garbage may be
* written in the output buffer beyond the point logically written to.
*
* In the case of the `*_without_replacement` variants, the status is a
* `uint32_t` whose possible values are packed info about a malformed byte
* sequence, `OUTPUT_FULL` and `INPUT_EMPTY` corresponding to the three cases
* listed above).
*
* Packed info about malformed sequences has the following format:
* The lowest 8 bits, which can have the decimal value 0, 1, 2 or 3,
* indicate the number of bytes that were consumed after the malformed
* sequence and whose next-lowest 8 bits, when shifted right by 8 indicate
* the length of the malformed byte sequence (possible decimal values 1, 2,
* 3 or 4). The maximum possible sum of the two is 6.
*
* In the case of methods whose name does not end with
* `*_without_replacement`, malformed sequences are automatically replaced
* with the REPLACEMENT CHARACTER and errors do not cause the methods to
* return early.
*
* When decoding to UTF-8, the output buffer must have at least 4 bytes of
* space. When decoding to UTF-16, the output buffer must have at least two
* UTF-16 code units (`char16_t`) of space.
*
* When decoding to UTF-8 without replacement, the methods are guaranteed
* not to return indicating that more output space is needed if the length
* of the output buffer is at least the length returned by
* `max_utf8_buffer_length_without_replacement()`. When decoding to UTF-8
* with replacement, the length of the output buffer that guarantees the
* methods not to return indicating that more output space is needed is given
* by `max_utf8_buffer_length()`. When decoding to UTF-16 with
* or without replacement, the length of the output buffer that guarantees
* the methods not to return indicating that more output space is needed is
* given by `max_utf16_buffer_length()`.
*
* The output written into `dst` is guaranteed to be valid UTF-8 or UTF-16,
* and the output after each `decode_*` call is guaranteed to consist of
* complete characters. (I.e. the code unit sequence for the last character is
* guaranteed not to be split across output buffers.)
*
* The boolean argument `last` indicates that the end of the stream is reached
* when all the bytes in `src` have been consumed.
*
* A `Decoder` object can be used to incrementally decode a byte stream.
*
* During the processing of a single stream, the caller must call `decode_*`
* zero or more times with `last` set to `false` and then call `decode_*` at
* least once with `last` set to `true`. If `decode_*` returns `INPUT_EMPTY`,
* the processing of the stream has ended. Otherwise, the caller must call
* `decode_*` again with `last` set to `true` (or treat a malformed result,
* i.e. neither `INPUT_EMPTY` nor `OUTPUT_FULL`, as a fatal error).
*
* Once the stream has ended, the `Decoder` object must not be used anymore.
* That is, you need to create another one to process another stream.
*
* When the decoder returns `OUTPUT_FULL` or the decoder returns a malformed
* result and the caller does not wish to treat it as a fatal error, the input
* buffer `src` may not have been completely consumed. In that case, the caller
* must pass the unconsumed contents of `src` to `decode_*` again upon the next
* call.
*
* # Infinite loops
*
* When converting with a fixed-size output buffer whose size is too small to
* accommodate one character of output, an infinite loop ensues. When
* converting with a fixed-size output buffer, it generally makes sense to
* make the buffer fairly large (e.g. couple of kilobytes).
*/
class Decoder final
{
public:
~Decoder() {}
static inline void operator delete(void* decoder)
{
decoder_free(reinterpret_cast<Decoder*>(decoder));
}
/**
* The `Encoding` this `Decoder` is for.
*
* BOM sniffing can change the return value of this method during the life
* of the decoder.
*/
inline gsl::not_null<const Encoding*> encoding() const
{
return gsl::not_null<const Encoding*>(decoder_encoding(this));
}
/**
* Query the worst-case UTF-8 output size _with replacement_.
*
* Returns the size of the output buffer in UTF-8 code units (`uint8_t`)
* that will not overflow given the current state of the decoder and
* `byte_length` number of additional input bytes when decoding with
* errors handled by outputting a REPLACEMENT CHARACTER for each malformed
* sequence or `std::optional` without value if `size_t` would overflow.
*/
inline std::optional<size_t> max_utf8_buffer_length(size_t byte_length) const
{
size_t val = decoder_max_utf8_buffer_length(this, byte_length);
if (val == SIZE_MAX) {
return std::nullopt;
}
return val;
}
/**
* Query the worst-case UTF-8 output size _without replacement_.
*
* Returns the size of the output buffer in UTF-8 code units (`uint8_t`)
* that will not overflow given the current state of the decoder and
* `byte_length` number of additional input bytes when decoding without
* replacement error handling or `std::optional` without value if `size_t`
* would overflow.
*
* Note that this value may be too small for the `_with_replacement` case.
* Use `max_utf8_buffer_length()` for that case.
*/
inline std::optional<size_t> max_utf8_buffer_length_without_replacement(
size_t byte_length) const
{
size_t val =
decoder_max_utf8_buffer_length_without_replacement(this, byte_length);
if (val == SIZE_MAX) {
return std::nullopt;
}
return val;
}
/**
* Incrementally decode a byte stream into UTF-8 with malformed sequences
* replaced with the REPLACEMENT CHARACTER.
*
* See the documentation of the class for documentation for `decode_*`
* methods collectively.
*/
inline std::tuple<uint32_t, size_t, size_t, bool> decode_to_utf8(
gsl::span<const uint8_t> src,
gsl::span<uint8_t> dst,
bool last)
{
size_t src_read = src.size();
size_t dst_written = dst.size();
bool had_replacements;
uint32_t result =
decoder_decode_to_utf8(this,
null_to_bogus<const uint8_t>(src.data()),
&src_read,
null_to_bogus<uint8_t>(dst.data()),
&dst_written,
last,
&had_replacements);
return { result, src_read, dst_written, had_replacements };
}
/**
* Incrementally decode a byte stream into UTF-8 _without replacement_.
*
* See the documentation of the class for documentation for `decode_*`
* methods collectively.
*/
inline std::tuple<uint32_t, size_t, size_t>
decode_to_utf8_without_replacement(gsl::span<const uint8_t> src,
gsl::span<uint8_t> dst,
bool last)
{
size_t src_read = src.size();
size_t dst_written = dst.size();
uint32_t result = decoder_decode_to_utf8_without_replacement(
this,
null_to_bogus<const uint8_t>(src.data()),
&src_read,
null_to_bogus<uint8_t>(dst.data()),
&dst_written,
last);
return { result, src_read, dst_written };
}
/**
* Query the worst-case UTF-16 output size (with or without replacement).
*
* Returns the size of the output buffer in UTF-16 code units (`char16_t`)
* that will not overflow given the current state of the decoder and
* `byte_length` number of additional input bytes or `std::optional`
* without value if `size_t` would overflow.
*
* Since the REPLACEMENT CHARACTER fits into one UTF-16 code unit, the
* return value of this method applies also in the
* `_without_replacement` case.
*/
inline std::optional<size_t> max_utf16_buffer_length(size_t byte_length) const
{
size_t val = decoder_max_utf16_buffer_length(this, byte_length);
if (val == SIZE_MAX) {
return std::nullopt;
}
return val;
}
/**
* Incrementally decode a byte stream into UTF-16 with malformed sequences
* replaced with the REPLACEMENT CHARACTER.
*
* See the documentation of the class for documentation for `decode_*`
* methods collectively.
*/
inline std::tuple<uint32_t, size_t, size_t, bool> decode_to_utf16(
gsl::span<const uint8_t> src,
gsl::span<char16_t> dst,
bool last)
{
size_t src_read = src.size();
size_t dst_written = dst.size();
bool had_replacements;
uint32_t result =
decoder_decode_to_utf16(this,
null_to_bogus<const uint8_t>(src.data()),
&src_read,
null_to_bogus<char16_t>(dst.data()),
&dst_written,
last,
&had_replacements);
return { result, src_read, dst_written, had_replacements };
}
/**
* Incrementally decode a byte stream into UTF-16 _without replacement_.
*
* See the documentation of the class for documentation for `decode_*`
* methods collectively.
*/
inline std::tuple<uint32_t, size_t, size_t>
decode_to_utf16_without_replacement(gsl::span<const uint8_t> src,
gsl::span<char16_t> dst,
bool last)
{
size_t src_read = src.size();
size_t dst_written = dst.size();
uint32_t result = decoder_decode_to_utf16_without_replacement(
this,
null_to_bogus<const uint8_t>(src.data()),
&src_read,
null_to_bogus<char16_t>(dst.data()),
&dst_written,
last);
return { result, src_read, dst_written };
}
private:
/**
* Replaces `nullptr` with a bogus pointer suitable for use as part of a
* zero-length Rust slice.
*/
template<class T>
static inline T* null_to_bogus(T* ptr)
{
return ptr ? ptr : reinterpret_cast<T*>(alignof(T));
}
Decoder() = delete;
Decoder(const Decoder&) = delete;
Decoder& operator=(const Decoder&) = delete;
};
/**
* A converter that encodes a Unicode stream into bytes according to a
* character encoding in a streaming (incremental) manner.
*
* The various `encode_*` methods take an input buffer (`src`) and an output
* buffer `dst` both of which are caller-allocated. There are variants for
* both UTF-8 and UTF-16 input buffers.
*
* An `encode_*` method encode characters from `src` into bytes characters
* stored into `dst` until one of the following three things happens:
*
* 1. An unmappable character is encountered (`*_without_replacement` variants
* only).
*
* 2. The output buffer has been filled so near capacity that the decoder
* cannot be sure that processing an additional character of input wouldn't
* cause so much output that the output buffer would overflow.
*
* 3. All the input characters have been processed.
*
* The `encode_*` method then returns tuple of a status indicating which one
* of the three reasons to return happened, how many input code units (`uint8_t`
* when encoding from UTF-8 and `char16_t` when encoding from UTF-16) were read,
* how many output bytes were written, and in the case of the variants that
* perform replacement, a boolean indicating whether an unmappable
* character was replaced with a numeric character reference during the call.
*
* The number of bytes "written" is what's logically written. Garbage may be
* written in the output buffer beyond the point logically written to.
*
* In the case of the methods whose name ends with
* `*_without_replacement`, the status is a `uint32_t` whose possible values
* are an unmappable code point, `OUTPUT_FULL` and `INPUT_EMPTY` corresponding
* to the three cases listed above).
*
* In the case of methods whose name does not end with
* `*_without_replacement`, unmappable characters are automatically replaced
* with the corresponding numeric character references and unmappable
* characters do not cause the methods to return early.
*
* When encoding from UTF-8 without replacement, the methods are guaranteed
* not to return indicating that more output space is needed if the length
* of the output buffer is at least the length returned by
* `max_buffer_length_from_utf8_without_replacement()`. When encoding from
* UTF-8 with replacement, the length of the output buffer that guarantees the
* methods not to return indicating that more output space is needed in the
* absence of unmappable characters is given by
* `max_buffer_length_from_utf8_if_no_unmappables()`. When encoding from
* UTF-16 without replacement, the methods are guaranteed not to return
* indicating that more output space is needed if the length of the output
* buffer is at least the length returned by
* `max_buffer_length_from_utf16_without_replacement()`. When encoding
* from UTF-16 with replacement, the the length of the output buffer that
* guarantees the methods not to return indicating that more output space is
* needed in the absence of unmappable characters is given by
* `max_buffer_length_from_utf16_if_no_unmappables()`.
* When encoding with replacement, applications are not expected to size the
* buffer for the worst case ahead of time but to resize the buffer if there
* are unmappable characters. This is why max length queries are only available
* for the case where there are no unmappable characters.
*
* When encoding from UTF-8, each `src` buffer _must_ be valid UTF-8. When
* encoding from UTF-16, unpaired surrogates in the input are treated as U+FFFD
* REPLACEMENT CHARACTERS. Therefore, in order for astral characters not to
* turn into a pair of REPLACEMENT CHARACTERS, the caller must ensure that
* surrogate pairs are not split across input buffer boundaries.
*
* After an `encode_*` call returns, the output produced so far, taken as a
* whole from the start of the stream, is guaranteed to consist of a valid
* byte sequence in the target encoding. (I.e. the code unit sequence for a
* character is guaranteed not to be split across output buffers. However, due
* to the stateful nature of ISO-2022-JP, the stream needs to be considered
* from the start for it to be valid. For other encodings, the validity holds
* on a per-output buffer basis.)
*
* The boolean argument `last` indicates that the end of the stream is reached
* when all the characters in `src` have been consumed. This argument is needed
* for ISO-2022-JP and is ignored for other encodings.
*
* An `Encoder` object can be used to incrementally encode a byte stream.
*
* During the processing of a single stream, the caller must call `encode_*`
* zero or more times with `last` set to `false` and then call `encode_*` at
* least once with `last` set to `true`. If `encode_*` returns `INPUT_EMPTY`,
* the processing of the stream has ended. Otherwise, the caller must call
* `encode_*` again with `last` set to `true` (or treat an unmappable result,
* i.e. neither `INPUT_EMPTY` nor `OUTPUT_FULL`, as a fatal error).
*
* Once the stream has ended, the `Encoder` object must not be used anymore.
* That is, you need to create another one to process another stream.
*
* When the encoder returns `OUTPUT_FULL` or the encoder returns an unmappable
* result and the caller does not wish to treat it as a fatal error, the input
* buffer `src` may not have been completely consumed. In that case, the caller
* must pass the unconsumed contents of `src` to `encode_*` again upon the next
* call.
*
* # Infinite loops
*
* When converting with a fixed-size output buffer whose size is too small to
* accommodate one character of output, an infinite loop ensues. When
* converting with a fixed-size output buffer, it generally makes sense to
* make the buffer fairly large (e.g. couple of kilobytes).
*/
class Encoder final
{
public:
~Encoder() {}
static inline void operator delete(void* encoder)
{
encoder_free(reinterpret_cast<Encoder*>(encoder));
}
/**
* The `Encoding` this `Encoder` is for.
*/
inline gsl::not_null<const Encoding*> encoding() const
{
return gsl::not_null<const Encoding*>(encoder_encoding(this));
}
/**
* Returns `true` if this is an ISO-2022-JP encoder that's not in the
* ASCII state and `false` otherwise.
*/
inline bool has_pending_state() const
{
return encoder_has_pending_state(this);
}
/**
* Query the worst-case output size when encoding from UTF-8 with
* replacement.
*
* Returns the size of the output buffer in bytes that will not overflow
* given the current state of the encoder and `byte_length` number of
* additional input code units if there are no unmappable characters in
* the input or `SIZE_MAX` if `size_t` would overflow.
*/
inline std::optional<size_t> max_buffer_length_from_utf8_if_no_unmappables(
size_t byte_length) const
{
size_t val =
encoder_max_buffer_length_from_utf8_if_no_unmappables(this, byte_length);
if (val == SIZE_MAX) {
return std::nullopt;
}
return val;
}
/**
* Query the worst-case output size when encoding from UTF-8 without
* replacement.
*
* Returns the size of the output buffer in bytes that will not overflow
* given the current state of the encoder and `byte_length` number of
* additional input code units or `SIZE_MAX` if `size_t` would overflow.
*/
inline std::optional<size_t> max_buffer_length_from_utf8_without_replacement(
size_t byte_length) const
{
size_t val = encoder_max_buffer_length_from_utf8_without_replacement(
this, byte_length);
if (val == SIZE_MAX) {
return std::nullopt;
}
return val;
}
/**
* Incrementally encode into byte stream from UTF-8 with unmappable
* characters replaced with HTML (decimal) numeric character references.
*
* See the documentation of the class for documentation for `encode_*`
* methods collectively.
*/
inline std::tuple<uint32_t, size_t, size_t, bool>
encode_from_utf8(std::string_view src, gsl::span<uint8_t> dst, bool last)
{
size_t src_read = src.size();
size_t dst_written = dst.size();
bool had_replacements;
uint32_t result =
encoder_encode_from_utf8(this,
null_to_bogus<const uint8_t>(
reinterpret_cast<const uint8_t*>(src.data())),
&src_read,
null_to_bogus<uint8_t>(dst.data()),
&dst_written,
last,
&had_replacements);
return { result, src_read, dst_written, had_replacements };
}
/**
* Incrementally encode into byte stream from UTF-8 _without replacement_.
*
* See the documentation of the class for documentation for `encode_*`
* methods collectively.
*/
inline std::tuple<uint32_t, size_t, size_t>
encode_from_utf8_without_replacement(std::string_view src,
gsl::span<uint8_t> dst,
bool last)
{
size_t src_read = src.size();
size_t dst_written = dst.size();
uint32_t result = encoder_encode_from_utf8_without_replacement(
this,
null_to_bogus<const uint8_t>(
reinterpret_cast<const uint8_t*>(src.data())),
&src_read,
null_to_bogus<uint8_t>(dst.data()),
&dst_written,
last);
return { result, src_read, dst_written };
}
/**
* Query the worst-case output size when encoding from UTF-16 with
* replacement.
*
* Returns the size of the output buffer in bytes that will not overflow
* given the current state of the encoder and `u16_length` number of
* additional input code units if there are no unmappable characters in
* the input or `SIZE_MAX` if `size_t` would overflow.
*/
inline std::optional<size_t> max_buffer_length_from_utf16_if_no_unmappables(
size_t u16_length) const
{
size_t val =
encoder_max_buffer_length_from_utf16_if_no_unmappables(this, u16_length);
if (val == SIZE_MAX) {
return std::nullopt;
}
return val;
}
/**
* Query the worst-case output size when encoding from UTF-16 without
* replacement.
*
* Returns the size of the output buffer in bytes that will not overflow
* given the current state of the encoder and `u16_length` number of
* additional input code units or `SIZE_MAX` if `size_t` would overflow.
*/
inline std::optional<size_t> max_buffer_length_from_utf16_without_replacement(
size_t u16_length) const
{
size_t val = encoder_max_buffer_length_from_utf16_without_replacement(
this, u16_length);
if (val == SIZE_MAX) {
return std::nullopt;
}
return val;
}
/**
* Incrementally encode into byte stream from UTF-16 with unmappable
* characters replaced with HTML (decimal) numeric character references.
*
* See the documentation of the class for documentation for `encode_*`
* methods collectively.
*/
inline std::tuple<uint32_t, size_t, size_t, bool>
encode_from_utf16(std::u16string_view src, gsl::span<uint8_t> dst, bool last)
{
size_t src_read = src.size();
size_t dst_written = dst.size();
bool had_replacements;
uint32_t result =
encoder_encode_from_utf16(this,
null_to_bogus<const char16_t>(src.data()),
&src_read,
null_to_bogus<uint8_t>(dst.data()),
&dst_written,
last,
&had_replacements);
return { result, src_read, dst_written, had_replacements };
}
/**
* Incrementally encode into byte stream from UTF-16 _without replacement_.
*
* See the documentation of the class for documentation for `encode_*`
* methods collectively.
*/
inline std::tuple<uint32_t, size_t, size_t>
encode_from_utf16_without_replacement(std::u16string_view src,
gsl::span<uint8_t> dst,
bool last)
{
size_t src_read = src.size();
size_t dst_written = dst.size();
uint32_t result = encoder_encode_from_utf16_without_replacement(
this,
null_to_bogus<const char16_t>(src.data()),
&src_read,
null_to_bogus<uint8_t>(dst.data()),
&dst_written,
last);
return { result, src_read, dst_written };
}
private:
/**
* Replaces `nullptr` with a bogus pointer suitable for use as part of a
* zero-length Rust slice.
*/
template<class T>
static inline T* null_to_bogus(T* ptr)
{
return ptr ? ptr : reinterpret_cast<T*>(alignof(T));
}
Encoder() = delete;
Encoder(const Encoder&) = delete;
Encoder& operator=(const Encoder&) = delete;
};
/**
* An encoding as defined in the Encoding Standard
* (https://encoding.spec.whatwg.org/).
*
* An _encoding_ defines a mapping from a byte sequence to a Unicode code point
* sequence and, in most cases, vice versa. Each encoding has a name, an output
* encoding, and one or more labels.
*
* _Labels_ are ASCII-case-insensitive strings that are used to identify an
* encoding in formats and protocols. The _name_ of the encoding is the
* preferred label in the case appropriate for returning from the
* `characterSet` property of the `Document` DOM interface, except for
* the replacement encoding whose name is not one of its labels.
*
* The _output encoding_ is the encoding used for form submission and URL
* parsing on Web pages in the encoding. This is UTF-8 for the replacement,
* UTF-16LE and UTF-16BE encodings and the encoding itself for other
* encodings.
*
* # Streaming vs. Non-Streaming
*
* When you have the entire input in a single buffer, you can use the
* methods `decode()`, `decode_with_bom_removal()`,
* `decode_without_bom_handling()`,
* `decode_without_bom_handling_and_without_replacement()` and
* `encode()`. Unlike the rest of the API, these methods perform heap
* allocations. You should the `Decoder` and `Encoder` objects when your input
* is split into multiple buffers or when you want to control the allocation of
* the output buffers.
*
* # Instances
*
* All instances of `Encoding` are statically allocated and have the process's
* lifetime. There is precisely one unique `Encoding` instance for each
* encoding defined in the Encoding Standard.
*
* To obtain a reference to a particular encoding whose identity you know at
* compile time, use a `static` that refers to encoding. There is a `static`
* for each encoding. The `static`s are named in all caps with hyphens
* replaced with underscores and with `_ENCODING` appended to the
* name. For example, if you know at compile time that you will want to
* decode using the UTF-8 encoding, use the `UTF_8_ENCODING` `static`.
*
* If you don't know what encoding you need at compile time and need to
* dynamically get an encoding by label, use `Encoding::for_label()`.
*
* Instances of `Encoding` can be compared with `==`.
*/
class Encoding final
{
public:
/**
* Implements the _get an encoding_ algorithm
* (https://encoding.spec.whatwg.org/#concept-encoding-get).
*
* If, after ASCII-lowercasing and removing leading and trailing
* whitespace, the argument matches a label defined in the Encoding
* Standard, `const Encoding*` representing the corresponding
* encoding is returned. If there is no match, `nullptr` is returned.
*
* This is the right method to use if the action upon the method returning
* `nullptr` is to use a fallback encoding (e.g. `WINDOWS_1252_ENCODING`)
* instead. When the action upon the method returning `nullptr` is not to
* proceed with a fallback but to refuse processing,
* `for_label_no_replacement()` is more appropriate.
*/
static inline const Encoding* for_label(gsl::cstring_span<> label)
{
return encoding_for_label(null_to_bogus<const uint8_t>(
reinterpret_cast<const uint8_t*>(label.data())),
label.length());
}
/**
* This method behaves the same as `for_label()`, except when `for_label()`
* would return `REPLACEMENT_ENCODING`, this method returns `nullptr` instead.
*
* This method is useful in scenarios where a fatal error is required
* upon invalid label, because in those cases the caller typically wishes
* to treat the labels that map to the replacement encoding as fatal
* errors, too.
*
* It is not OK to use this method when the action upon the method returning
* `nullptr` is to use a fallback encoding (e.g. `WINDOWS_1252_ENCODING`). In
* such a case, the `for_label()` method should be used instead in order to
* avoid
* unsafe fallback for labels that `for_label()` maps to
* `REPLACEMENT_ENCODING`.
*/
static inline const Encoding* for_label_no_replacement(
gsl::cstring_span<> label)
{
return encoding_for_label_no_replacement(
null_to_bogus<const uint8_t>(
reinterpret_cast<const uint8_t*>(label.data())),
label.length());
}
/**
* Performs non-incremental BOM sniffing.
*
* The argument must either be a buffer representing the entire input
* stream (non-streaming case) or a buffer representing at least the first
* three bytes of the input stream (streaming case).
*
* Returns a std::optinal wrapping `make_tuple(UTF_8_ENCODING, 3)`,
* `make_tuple(UTF_16LE_ENCODING, 2)` or `make_tuple(UTF_16BE_ENCODING, 3)`
* if the argument starts with the UTF-8, UTF-16LE or UTF-16BE BOM or
* `std::nullopt` otherwise.
*/
static inline std::optional<
std::tuple<gsl::not_null<const Encoding*>, size_t>>
for_bom(gsl::span<const uint8_t> buffer)
{
size_t len = buffer.size();
const Encoding* encoding =
encoding_for_bom(null_to_bogus(buffer.data()), &len);
if (encoding) {
return std::make_tuple(gsl::not_null<const Encoding*>(encoding), len);
}
return std::nullopt;
}
/**
* Returns the name of this encoding.
*
* This name is appropriate to return as-is from the DOM
* `document.characterSet` property.
*/
inline std::string name() const
{
std::string name(ENCODING_NAME_MAX_LENGTH, '\0');
// http://herbsutter.com/2008/04/07/cringe-not-vectors-are-guaranteed-to-be-contiguous/#comment-483
size_t length = encoding_name(this, reinterpret_cast<uint8_t*>(&name[0]));
name.resize(length);
return name;
}
/**
* Checks whether the _output encoding_ of this encoding can encode every
* Unicode code point. (Only true if the output encoding is UTF-8.)
*/
inline bool can_encode_everything() const
{
return encoding_can_encode_everything(this);
}
/**
* Checks whether the bytes 0x00...0x7F map exclusively to the characters
* U+0000...U+007F and vice versa.
*/
inline bool is_ascii_compatible() const
{
return encoding_is_ascii_compatible(this);
}
/**
* Checks whether this encoding maps one byte to one Basic Multilingual
* Plane code point (i.e. byte length equals decoded UTF-16 length) and
* vice versa (for mappable characters).
*
* `true` iff this encoding is on the list of Legacy single-byte
* encodings (https://encoding.spec.whatwg.org/#legacy-single-byte-encodings)
* in the spec or x-user-defined.
*/
inline bool is_single_byte() const
{
return encoding_is_single_byte(this);
}
/**
* Returns the _output encoding_ of this encoding. This is UTF-8 for
* UTF-16BE, UTF-16LE and replacement and the encoding itself otherwise.
*/
inline gsl::not_null<const Encoding*> output_encoding() const
{
return gsl::not_null<const Encoding*>(encoding_output_encoding(this));
}
/**
* Decode complete input to `std::string` _with BOM sniffing_ and with
* malformed sequences replaced with the REPLACEMENT CHARACTER when the
* entire input is available as a single buffer (i.e. the end of the
* buffer marks the end of the stream).
*
* This method implements the (non-streaming version of) the
* _decode_ (https://encoding.spec.whatwg.org/#decode) spec concept.
*
* The second item in the returned tuple is the encoding that was actually
* used (which may differ from this encoding thanks to BOM sniffing).
*
* The third item in the returned tuple indicates whether there were
* malformed sequences (that were replaced with the REPLACEMENT CHARACTER).
*
* _Note:_ It is wrong to use this when the input buffer represents only
* a segment of the input instead of the whole input. Use `new_decoder()`
* when decoding segmented input.
*/
inline std::tuple<std::string, gsl::not_null<const Encoding*>, bool> decode(
gsl::span<const uint8_t> bytes) const
{
auto opt = Encoding::for_bom(bytes);
const Encoding* encoding;
if (opt) {
size_t bom_length;
std::tie(encoding, bom_length) = *opt;
bytes = bytes.subspan(bom_length);
} else {
encoding = this;
}
auto [str, had_errors] = encoding->decode_without_bom_handling(bytes);
return { str, gsl::not_null<const Encoding*>(encoding), had_errors };
}
/**
* Decode complete input to `std::string` _with BOM removal_ and with
* malformed sequences replaced with the REPLACEMENT CHARACTER when the
* entire input is available as a single buffer (i.e. the end of the
* buffer marks the end of the stream).
*
* When invoked on `UTF_8`, this method implements the (non-streaming
* version of) the _UTF-8 decode_
* (https://encoding.spec.whatwg.org/#utf-8-decode) spec concept.
*
* The second item in the returned pair indicates whether there were
* malformed sequences (that were replaced with the REPLACEMENT CHARACTER).
*
* _Note:_ It is wrong to use this when the input buffer represents only
* a segment of the input instead of the whole input. Use
* `new_decoder_with_bom_removal()` when decoding segmented input.
*/
inline std::tuple<std::string, bool> decode_with_bom_removal(
gsl::span<const uint8_t> bytes) const
{
if (this == UTF_8_ENCODING && bytes.size() >= 3 &&
(gsl::as_bytes(bytes.first<3>()) ==
gsl::as_bytes(gsl::make_span("\xEF\xBB\xBF")))) {
bytes = bytes.subspan(3, bytes.size() - 3);
} else if (this == UTF_16LE_ENCODING && bytes.size() >= 2 &&
(gsl::as_bytes(bytes.first<2>()) ==
gsl::as_bytes(gsl::make_span("\xFF\xFE")))) {
bytes = bytes.subspan(2, bytes.size() - 2);
} else if (this == UTF_16BE_ENCODING && bytes.size() >= 2 &&
(gsl::as_bytes(bytes.first<2>()) ==
gsl::as_bytes(gsl::make_span("\xFE\xFF")))) {
bytes = bytes.subspan(2, bytes.size() - 2);
}
return decode_without_bom_handling(bytes);
}
/**
* Decode complete input to `std::string` _without BOM handling_ and
* with malformed sequences replaced with the REPLACEMENT CHARACTER when
* the entire input is available as a single buffer (i.e. the end of the
* buffer marks the end of the stream).
*
* When invoked on `UTF_8`, this method implements the (non-streaming
* version of) the _UTF-8 decode without BOM_
* (https://encoding.spec.whatwg.org/#utf-8-decode-without-bom) spec concept.
*
* The second item in the returned pair indicates whether there were
* malformed sequences (that were replaced with the REPLACEMENT CHARACTER).
*
* _Note:_ It is wrong to use this when the input buffer represents only
* a segment of the input instead of the whole input. Use
* `new_decoder_without_bom_handling()` when decoding segmented input.
*/
inline std::tuple<std::string, bool> decode_without_bom_handling(
gsl::span<const uint8_t> bytes) const
{
auto decoder = new_decoder_without_bom_handling();
auto needed = decoder->max_utf8_buffer_length(bytes.size());
if (!needed) {
throw std::overflow_error("Overflow in buffer size computation.");
}
std::string string(needed.value(), '\0');
const auto [result, read, written, had_errors] = decoder->decode_to_utf8(
bytes,
gsl::make_span(reinterpret_cast<uint8_t*>(&string[0]), string.size()),
true);
assert(read == static_cast<size_t>(bytes.size()));
assert(written <= static_cast<size_t>(string.size()));
assert(result == INPUT_EMPTY);
string.resize(written);
return { string, had_errors };
}
/**
* Decode complete input to `std::string` _without BOM handling_ and
* _with malformed sequences treated as fatal_ when the entire input is
* available as a single buffer (i.e. the end of the buffer marks the end
* of the stream).
*
* When invoked on `UTF_8`, this method implements the (non-streaming
* version of) the _UTF-8 decode without BOM or fail_
* (https://encoding.spec.whatwg.org/#utf-8-decode-without-bom-or-fail)
* spec concept.
*
* Returns `None` if a malformed sequence was encountered and the result
* of the decode as `Some(String)` otherwise.
*
* _Note:_ It is wrong to use this when the input buffer represents only
* a segment of the input instead of the whole input. Use
* `new_decoder_without_bom_handling()` when decoding segmented input.
*/
inline std::optional<std::string>
decode_without_bom_handling_and_without_replacement(
gsl::span<const uint8_t> bytes) const
{
auto decoder = new_decoder_without_bom_handling();
auto needed =
decoder->max_utf8_buffer_length_without_replacement(bytes.size());
if (!needed) {
throw std::overflow_error("Overflow in buffer size computation.");
}
std::string string(needed.value(), '\0');
const auto [result, read, written] =
decoder->decode_to_utf8_without_replacement(
bytes,
gsl::make_span(reinterpret_cast<uint8_t*>(&string[0]), string.size()),
true);
assert(result != OUTPUT_FULL);
if (result == INPUT_EMPTY) {
assert(read == static_cast<size_t>(bytes.size()));
assert(written <= static_cast<size_t>(string.size()));
string.resize(written);
return string;
}
}
/**
* Decode complete input to `std::u16string` _with BOM sniffing_ and with
* malformed sequences replaced with the REPLACEMENT CHARACTER when the
* entire input is available as a single buffer (i.e. the end of the
* buffer marks the end of the stream).
*
* This method implements the (non-streaming version of) the
* _decode_ (https://encoding.spec.whatwg.org/#decode) spec concept.
*
* The second item in the returned tuple is the encoding that was actually
* used (which may differ from this encoding thanks to BOM sniffing).
*
* The third item in the returned tuple indicates whether there were
* malformed sequences (that were replaced with the REPLACEMENT CHARACTER).
*
* _Note:_ It is wrong to use this when the input buffer represents only
* a segment of the input instead of the whole input. Use `new_decoder()`
* when decoding segmented input.
*/
inline std::tuple<std::u16string, gsl::not_null<const Encoding*>, bool>
decode16(gsl::span<const uint8_t> bytes) const
{
auto opt = Encoding::for_bom(bytes);
const Encoding* encoding;
if (opt) {
size_t bom_length;
std::tie(encoding, bom_length) = *opt;
bytes = bytes.subspan(bom_length);
} else {
encoding = this;
}
auto [str, had_errors] = encoding->decode16_without_bom_handling(bytes);
return { str, gsl::not_null<const Encoding*>(encoding), had_errors };
}
/**
* Decode complete input to `std::u16string` _with BOM removal_ and with
* malformed sequences replaced with the REPLACEMENT CHARACTER when the
* entire input is available as a single buffer (i.e. the end of the
* buffer marks the end of the stream).
*
* When invoked on `UTF_8`, this method implements the (non-streaming
* version of) the _UTF-8 decode_
* (https://encoding.spec.whatwg.org/#utf-8-decode) spec concept.
*
* The second item in the returned pair indicates whether there were
* malformed sequences (that were replaced with the REPLACEMENT CHARACTER).
*
* _Note:_ It is wrong to use this when the input buffer represents only
* a segment of the input instead of the whole input. Use
* `new_decoder_with_bom_removal()` when decoding segmented input.
*/
inline std::tuple<std::u16string, bool> decode16_with_bom_removal(
gsl::span<const uint8_t> bytes) const
{
if (this == UTF_8_ENCODING && bytes.size() >= 3 &&
(gsl::as_bytes(bytes.first<3>()) ==
gsl::as_bytes(gsl::make_span("\xEF\xBB\xBF")))) {
bytes = bytes.subspan(3, bytes.size() - 3);
} else if (this == UTF_16LE_ENCODING && bytes.size() >= 2 &&
(gsl::as_bytes(bytes.first<2>()) ==
gsl::as_bytes(gsl::make_span("\xFF\xFE")))) {
bytes = bytes.subspan(2, bytes.size() - 2);
} else if (this == UTF_16BE_ENCODING && bytes.size() >= 2 &&
(gsl::as_bytes(bytes.first<2>()) ==
gsl::as_bytes(gsl::make_span("\xFE\xFF")))) {
bytes = bytes.subspan(2, bytes.size() - 2);
}
return decode16_without_bom_handling(bytes);
}
/**
* Decode complete input to `std::u16string` _without BOM handling_ and
* with malformed sequences replaced with the REPLACEMENT CHARACTER when
* the entire input is available as a single buffer (i.e. the end of the
* buffer marks the end of the stream).
*
* When invoked on `UTF_8`, this method implements the (non-streaming
* version of) the _UTF-8 decode without BOM_
* (https://encoding.spec.whatwg.org/#utf-8-decode-without-bom) spec concept.
*
* The second item in the returned pair indicates whether there were
* malformed sequences (that were replaced with the REPLACEMENT CHARACTER).
*
* _Note:_ It is wrong to use this when the input buffer represents only
* a segment of the input instead of the whole input. Use
* `new_decoder_without_bom_handling()` when decoding segmented input.
*/
inline std::tuple<std::u16string, bool> decode16_without_bom_handling(
gsl::span<const uint8_t> bytes) const
{
auto decoder = new_decoder_without_bom_handling();
auto needed = decoder->max_utf16_buffer_length(bytes.size());
if (!needed) {
throw std::overflow_error("Overflow in buffer size computation.");
}
std::u16string string(needed.value(), '\0');
const auto [result, read, written, had_errors] = decoder->decode_to_utf16(
bytes, gsl::make_span(&string[0], string.size()), true);
assert(read == static_cast<size_t>(bytes.size()));
assert(written <= static_cast<size_t>(string.size()));
assert(result == INPUT_EMPTY);
string.resize(written);
return { string, had_errors };
}
/**
* Decode complete input to `std::u16string` _without BOM handling_ and
* _with malformed sequences treated as fatal_ when the entire input is
* available as a single buffer (i.e. the end of the buffer marks the end
* of the stream).
*
* When invoked on `UTF_8`, this method implements the (non-streaming
* version of) the _UTF-8 decode without BOM or fail_
* (https://encoding.spec.whatwg.org/#utf-8-decode-without-bom-or-fail)
* spec concept.
*
* Returns `None` if a malformed sequence was encountered and the result
* of the decode as `Some(String)` otherwise.
*
* _Note:_ It is wrong to use this when the input buffer represents only
* a segment of the input instead of the whole input. Use
* `new_decoder_without_bom_handling()` when decoding segmented input.
*/
inline std::optional<std::u16string>
decode16_without_bom_handling_and_without_replacement(
gsl::span<const uint8_t> bytes) const
{
auto decoder = new_decoder_without_bom_handling();
auto needed = decoder->max_utf16_buffer_length(bytes.size());
if (!needed) {
throw std::overflow_error("Overflow in buffer size computation.");
}
std::u16string string(needed.value(), '\0');
const auto [result, read, written] =
decoder->decode_to_utf16_without_replacement(
bytes, gsl::make_span(&string[0], string.size()), true);
assert(result != OUTPUT_FULL);
if (result == INPUT_EMPTY) {
assert(read == static_cast<size_t>(bytes.size()));
assert(written <= static_cast<size_t>(string.size()));
string.resize(written);
return string;
}
}
/**
* Encode complete input to `std::vector<uint8_t>` with unmappable characters
* replaced with decimal numeric character references when the entire input
* is available as a single buffer (i.e. the end of the buffer marks the
* end of the stream).
*
* This method implements the (non-streaming version of) the
* _encode_ (https://encoding.spec.whatwg.org/#encode) spec concept.
*
* The second item in the returned tuple is the encoding that was actually
* used (which may differ from this encoding thanks to some encodings
* having UTF-8 as their output encoding).
*
* The third item in the returned tuple indicates whether there were
* unmappable characters (that were replaced with HTML numeric character
* references).
*
* _Note:_ It is wrong to use this when the input buffer represents only
* a segment of the input instead of the whole input. Use `new_encoder()`
* when encoding segmented output.
*/
inline std::tuple<std::vector<uint8_t>, gsl::not_null<const Encoding*>, bool>
encode(std::string_view string) const
{
auto output_enc = output_encoding();
if (output_enc == UTF_8_ENCODING) {
std::vector<uint8_t> vec(string.size());
std::memcpy(&vec[0], string.data(), string.size());
}
auto encoder = output_enc->new_encoder();
auto needed =
encoder->max_buffer_length_from_utf8_if_no_unmappables(string.size());
if (!needed) {
throw std::overflow_error("Overflow in buffer size computation.");
}
std::vector<uint8_t> vec(needed.value());
bool total_had_errors = false;
size_t total_read = 0;
size_t total_written = 0;
for (;;) {
const auto [result, read, written, had_errors] =
encoder->encode_from_utf8(string.substr(total_read),
gsl::make_span(vec).subspan(total_written),
true);
total_read += read;
total_written += written;
total_had_errors |= had_errors;
if (result == INPUT_EMPTY) {
assert(total_read == static_cast<size_t>(string.size()));
assert(total_written <= static_cast<size_t>(vec.size()));
vec.resize(total_written);
return { vec,
gsl::not_null<const Encoding*>(output_enc),
total_had_errors };
}
auto needed = encoder->max_buffer_length_from_utf8_if_no_unmappables(
string.size() - total_read);
if (!needed) {
throw std::overflow_error("Overflow in buffer size computation.");
}
vec.resize(total_written + needed.value());
}
}
/**
* Encode complete input to `std::vector<uint8_t>` with unmappable characters
* replaced with decimal numeric character references when the entire input
* is available as a single buffer (i.e. the end of the buffer marks the
* end of the stream).
*
* This method implements the (non-streaming version of) the
* _encode_ (https://encoding.spec.whatwg.org/#encode) spec concept.
*
* The second item in the returned tuple is the encoding that was actually
* used (which may differ from this encoding thanks to some encodings
* having UTF-8 as their output encoding).
*
* The third item in the returned tuple indicates whether there were
* unmappable characters (that were replaced with HTML numeric character
* references).
*
* _Note:_ It is wrong to use this when the input buffer represents only
* a segment of the input instead of the whole input. Use `new_encoder()`
* when encoding segmented output.
*/
inline std::tuple<std::vector<uint8_t>, gsl::not_null<const Encoding*>, bool>
encode(std::u16string_view string) const
{
auto output_enc = output_encoding();
auto encoder = output_enc->new_encoder();
auto needed =
encoder->max_buffer_length_from_utf16_if_no_unmappables(string.size());
if (!needed) {
throw std::overflow_error("Overflow in buffer size computation.");
}
std::vector<uint8_t> vec(needed.value());
bool total_had_errors = false;
size_t total_read = 0;
size_t total_written = 0;
for (;;) {
const auto [result, read, written, had_errors] =
encoder->encode_from_utf16(string.substr(total_read),
gsl::make_span(vec).subspan(total_written),
true);
total_read += read;
total_written += written;
total_had_errors |= had_errors;
if (result == INPUT_EMPTY) {
assert(total_read == static_cast<size_t>(string.size()));
assert(total_written <= static_cast<size_t>(vec.size()));
vec.resize(total_written);
return { vec,
gsl::not_null<const Encoding*>(output_enc),
total_had_errors };
}
auto needed = encoder->max_buffer_length_from_utf16_if_no_unmappables(
string.size() - total_read);
if (!needed) {
throw std::overflow_error("Overflow in buffer size computation.");
}
vec.resize(total_written + needed.value());
}
}
/**
* Instantiates a new decoder for this encoding with BOM sniffing enabled.
*
* BOM sniffing may cause the returned decoder to morph into a decoder
* for UTF-8, UTF-16LE or UTF-16BE instead of this encoding.
*/
inline std::unique_ptr<Decoder> new_decoder() const
{
return std::unique_ptr<Decoder>(encoding_new_decoder(this));
}
/**
* Instantiates a new decoder for this encoding with BOM sniffing enabled
* into memory occupied by a previously-instantiated decoder.
*
* BOM sniffing may cause the returned decoder to morph into a decoder
* for UTF-8, UTF-16LE or UTF-16BE instead of this encoding.
*/
inline void new_decoder_into(Decoder& decoder) const
{
encoding_new_decoder_into(this, &decoder);
}
/**
* Instantiates a new decoder for this encoding with BOM removal.
*
* If the input starts with bytes that are the BOM for this encoding,
* those bytes are removed. However, the decoder never morphs into a
* decoder for another encoding: A BOM for another encoding is treated as
* (potentially malformed) input to the decoding algorithm for this
* encoding.
*/
inline std::unique_ptr<Decoder> new_decoder_with_bom_removal() const
{
return std::unique_ptr<Decoder>(
encoding_new_decoder_with_bom_removal(this));
}
/**
* Instantiates a new decoder for this encoding with BOM removal
* into memory occupied by a previously-instantiated decoder.
*
* If the input starts with bytes that are the BOM for this encoding,
* those bytes are removed. However, the decoder never morphs into a
* decoder for another encoding: A BOM for another encoding is treated as
* (potentially malformed) input to the decoding algorithm for this
* encoding.
*/
inline void new_decoder_with_bom_removal_into(Decoder& decoder) const
{
encoding_new_decoder_with_bom_removal_into(this, &decoder);
}
/**
* Instantiates a new decoder for this encoding with BOM handling disabled.
*
* If the input starts with bytes that look like a BOM, those bytes are
* not treated as a BOM. (Hence, the decoder never morphs into a decoder
* for another encoding.)
*
* _Note:_ If the caller has performed BOM sniffing on its own but has not
* removed the BOM, the caller should use `new_decoder_with_bom_removal()`
* instead of this method to cause the BOM to be removed.
*/
inline std::unique_ptr<Decoder> new_decoder_without_bom_handling() const
{
return std::unique_ptr<Decoder>(
encoding_new_decoder_without_bom_handling(this));
}
/**
* Instantiates a new decoder for this encoding with BOM handling disabled
* into memory occupied by a previously-instantiated decoder.
*
* If the input starts with bytes that look like a BOM, those bytes are
* not treated as a BOM. (Hence, the decoder never morphs into a decoder
* for another encoding.)
*
* _Note:_ If the caller has performed BOM sniffing on its own but has not
* removed the BOM, the caller should use
* `new_decoder_with_bom_removal_into()`
* instead of this method to cause the BOM to be removed.
*/
inline void new_decoder_without_bom_handling_into(Decoder& decoder) const
{
encoding_new_decoder_without_bom_handling_into(this, &decoder);
}
/**
* Instantiates a new encoder for the output encoding of this encoding.
*/
inline std::unique_ptr<Encoder> new_encoder() const
{
return std::unique_ptr<Encoder>(encoding_new_encoder(this));
}
/**
* Instantiates a new encoder for the output encoding of this encoding
* into memory occupied by a previously-instantiated encoder.
*/
inline void new_encoder_into(Encoder& encoder) const
{
encoding_new_encoder_into(this, &encoder);
}
/**
* Validates UTF-8.
*
* Returns the index of the first byte that makes the input malformed as
* UTF-8 or the length of the input if the input is entirely valid.
*/
static inline size_t utf8_valid_up_to(gsl::span<const uint8_t> buffer)
{
return encoding_utf8_valid_up_to(
null_to_bogus<const uint8_t>(buffer.data()), buffer.size());
}
/**
* Validates ASCII.
*
* Returns the index of the first byte that makes the input malformed as
* ASCII or the length of the input if the input is entirely valid.
*/
static inline size_t ascii_valid_up_to(gsl::span<const uint8_t> buffer)
{
return encoding_ascii_valid_up_to(
null_to_bogus<const uint8_t>(buffer.data()), buffer.size());
}
/**
* Validates ISO-2022-JP ASCII-state data.
*
* Returns the index of the first byte that makes the input not
* representable in the ASCII state of ISO-2022-JP or the length of the
* input if the input is entirely representable in the ASCII state of
* ISO-2022-JP.
*/
static inline size_t iso_2022_jp_ascii_valid_up_to(
gsl::span<const uint8_t> buffer)
{
return encoding_iso_2022_jp_ascii_valid_up_to(
null_to_bogus<const uint8_t>(buffer.data()), buffer.size());
}
private:
/**
* Replaces `nullptr` with a bogus pointer suitable for use as part of a
* zero-length Rust slice.
*/
template<class T>
static inline T* null_to_bogus(T* ptr)
{
return ptr ? ptr : reinterpret_cast<T*>(alignof(T));
}
Encoding() = delete;
Encoding(const Encoding&) = delete;
Encoding& operator=(const Encoding&) = delete;
~Encoding() = delete;
};
}; // namespace encoding_rs
#endif // encoding_rs_cpp_h_