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Diffstat (limited to 'src/third-party/scnlib/include/scn/reader/common.h')
| -rw-r--r-- | src/third-party/scnlib/include/scn/reader/common.h | 1663 |
1 files changed, 1663 insertions, 0 deletions
diff --git a/src/third-party/scnlib/include/scn/reader/common.h b/src/third-party/scnlib/include/scn/reader/common.h new file mode 100644 index 0000000..0f2b83b --- /dev/null +++ b/src/third-party/scnlib/include/scn/reader/common.h @@ -0,0 +1,1663 @@ +// Copyright 2017 Elias Kosunen +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. +// +// This file is a part of scnlib: +// https://github.com/eliaskosunen/scnlib + +#ifndef SCN_READER_COMMON_H +#define SCN_READER_COMMON_H + +#include "../detail/error.h" +#include "../detail/locale.h" +#include "../detail/range.h" +#include "../unicode/unicode.h" +#include "../util/algorithm.h" + +namespace scn { + SCN_BEGIN_NAMESPACE + + // read_code_unit + + namespace detail { + template <typename WrappedRange> + expected<typename WrappedRange::char_type> + read_code_unit_impl(WrappedRange& r, bool advance, std::true_type) + { + SCN_CLANG_PUSH + // clang 10 behaves weirdly + SCN_CLANG_IGNORE("-Wzero-as-null-pointer-constant") + SCN_EXPECT(r.begin() < r.end()); + SCN_CLANG_POP + auto ch = *r.begin(); + if (advance) { + r.advance(); + } + return {ch}; + } + template <typename WrappedRange> + expected<typename WrappedRange::char_type> + read_code_unit_impl(WrappedRange& r, bool advance, std::false_type) + { + SCN_EXPECT(r.begin() != r.end()); + auto ch = *r.begin(); + if (advance && ch) { + r.advance(); + } + return ch; + } + } // namespace detail + + /** + * Reads a single character (= code unit) from the range. + * Dereferences the begin iterator, wrapping it in an `expected` if + * necessary. + * + * Encoding-agnostic, doesn't care about code points, and may leave behind + * partial ones. + * + * \param r Range to read from + * \param advance If `true`, and the read was successful, the range is + * advanced by a single character, as if by calling `r.advance()`. + * + * \return The next character in the range, obtained as if by dereferencing + * the begin iterator `*r.begin()`. + * If `r.begin() == r.end()`, returns EOF. + * If `r` is direct, returns `*r.begin()` wrapped in an `expected`. + * If `r` is not direct, returns `*r.begin()` as-is, with any errors that + * may have been caused by the read. + */ + template <typename WrappedRange> + expected<typename WrappedRange::char_type> read_code_unit( + WrappedRange& r, + bool advance = true) + { + if (r.begin() == r.end()) { + return error(error::end_of_range, "EOF"); + } + return detail::read_code_unit_impl( + r, advance, + std::integral_constant<bool, WrappedRange::is_direct>{}); + } + + // putback_n + + /// @{ + + /** + * Puts back `n` characters (= code units) into `r` as if by repeatedly + * calling `r.advance(-1)`. + * + * Encoding-agnostic, may leave behind partial code points. + * + * \param r Range to roll back + * \param n Characters to put back, must be less than or equal to the number + * of characters already read from `r`. + * + * \return If `r` is contiguous, will always return `error::good`. + * Otherwise, may return `error::unrecoverable_source_error`, if the putback + * fails. + */ + template < + typename WrappedRange, + typename std::enable_if<WrappedRange::is_contiguous>::type* = nullptr> + error putback_n(WrappedRange& r, ranges::range_difference_t<WrappedRange> n) + { + SCN_EXPECT(n <= ranges::distance(r.begin_underlying(), r.begin())); + r.advance(-n); + return {}; + } + template < + typename WrappedRange, + typename std::enable_if<!WrappedRange::is_contiguous>::type* = nullptr> + error putback_n(WrappedRange& r, ranges::range_difference_t<WrappedRange> n) + { + for (ranges::range_difference_t<WrappedRange> i = 0; i < n; ++i) { + r.advance(-1); + if (r.begin() == r.end()) { + return {error::unrecoverable_source_error, "Putback failed"}; + } + } + return {}; + } + + /// @} + + // read_code_point + + /** + * Type returned by `read_code_point` + * \tparam CharT Character type of the range + */ + template <typename CharT> + struct read_code_point_result { + /// Code units, may point to `writebuf` given to `read_code_point` + span<const CharT> chars; + /// Parsed code point + code_point cp; + }; + + namespace detail { + // contiguous && direct + template <typename CharT, typename WrappedRange> + expected<read_code_point_result<CharT>> read_code_point_impl( + WrappedRange& r, + span<CharT> writebuf, + std::true_type) + { + if (r.begin() == r.end()) { + return error(error::end_of_range, "EOF"); + } + + auto sbuf = r.get_buffer_and_advance(4 / sizeof(CharT)); + if (sbuf.size() == 0) { + auto ret = read_code_unit(r, true); + if (!ret) { + return ret.error(); + } + sbuf = writebuf.first(1); + writebuf[0] = ret.value(); + } + int len = ::scn::get_sequence_length(sbuf[0]); + if (SCN_UNLIKELY(len == 0)) { + return error(error::invalid_encoding, "Invalid code point"); + } + if (sbuf.ssize() > len) { + auto e = putback_n(r, sbuf.ssize() - len); + if (!e) { + return e; + } + sbuf = sbuf.first(static_cast<size_t>(len)); + } + if (len == 1) { + // Single-char code point + return read_code_point_result<CharT>{sbuf.first(1), + make_code_point(sbuf[0])}; + } + while (sbuf.ssize() < len) { + auto ret = read_code_unit(r, true); + if (!ret) { + auto e = putback_n(r, sbuf.ssize()); + if (!e) { + return e; + } + if (ret.error().code() == error::end_of_range) { + return error(error::invalid_encoding, + "Invalid code point"); + } + return ret.error(); + } + sbuf = make_span(writebuf.begin(), sbuf.size() + 1); + writebuf[sbuf.size() - 1] = ret.value(); + } + + code_point cp{}; + auto ret = parse_code_point(sbuf.begin(), sbuf.end(), cp); + if (!ret) { + return ret.error(); + } + return read_code_point_result<CharT>{sbuf, cp}; + } + + template <typename CharT, typename WrappedRange> + expected<read_code_point_result<CharT>> read_code_point_impl( + WrappedRange& r, + span<CharT> writebuf, + std::false_type) + { + auto first = read_code_unit(r, false); + if (!first) { + return first.error(); + } + + auto len = + static_cast<size_t>(::scn::get_sequence_length(first.value())); + if (SCN_UNLIKELY(len == 0)) { + return error(error::invalid_encoding, "Invalid code point"); + } + r.advance(); + + writebuf[0] = first.value(); + if (len == 1) { + // Single-char code point + return read_code_point_result<CharT>{ + make_span(writebuf.data(), 1), + make_code_point(first.value())}; + } + + size_t index = 1; + + auto parse = [&]() -> expected<read_code_point_result<CharT>> { + code_point cp{}; + auto ret = parse_code_point(writebuf.data(), + writebuf.data() + len, cp); + if (!ret) { + auto pb = putback_n(r, static_cast<std::ptrdiff_t>(len)); + if (!pb) { + return pb; + } + return ret.error(); + } + auto s = make_span(writebuf.data(), len); + return read_code_point_result<CharT>{s, cp}; + }; + auto advance = [&]() -> error { + auto ret = read_code_unit(r, false); + if (!ret) { + auto pb = putback_n(r, static_cast<std::ptrdiff_t>(index)); + if (!pb) { + return pb; + } + return ret.error(); + } + writebuf[index] = ret.value(); + ++index; + r.advance(); + return {}; + }; + + while (index < 4) { + auto e = advance(); + if (!e) { + return e; + } + if (index == len) { + return parse(); + } + } + SCN_ENSURE(false); + SCN_UNREACHABLE; + } + } // namespace detail + + /** + * Read a single Unicode code point from `r` as if by repeatedly calling + * `read_code_unit()`. + * + * Advances the range past the read code point. On error, rolls back the + * range into the state it was before calling this function, as if by + * calling `putback_n()`. + * + * \param r Range to read from + * \param writebuf Buffer to use for reading into, if necessary. `BufValueT` + * can be any trivial type. Must be at least 4 bytes long. May be written + * over. + * + * \return An instance of `read_code_point_result`, wrapped in an + * `expected`. `chars` contains the code units read from `r`, which may + * point to `writebuf`. `cp` contains the code point parsed. + * If `r.begin() == r.end()`, returns EOF. + * If `read_code_unit()` or `putback_n()` fails, returns any errors returned + * by it. + * If the code point was not encoded correctly, returns + * `error::invalid_encoding`. + */ + template <typename WrappedRange, typename BufValueT> + expected<read_code_point_result<typename WrappedRange::char_type>> + read_code_point(WrappedRange& r, span<BufValueT> writebuf) + { + SCN_EXPECT(writebuf.size() * sizeof(BufValueT) >= 4); + using char_type = typename WrappedRange::char_type; + SCN_GCC_PUSH + SCN_GCC_IGNORE("-Wcast-align") // taken care of by the caller + return detail::read_code_point_impl<char_type>( + r, + make_span(reinterpret_cast<char_type*>(writebuf.data()), + writebuf.size() * sizeof(BufValueT) / sizeof(char_type)), + std::integral_constant<bool, + WrappedRange::provides_buffer_access>{}); + SCN_GCC_POP + } + + // read_zero_copy + + /// @{ + + /** + * Reads up to `n` characters (= code units) from `r`, as if by repeatedly + * incrementing `r.begin()`, and returns a `span` pointing into `r`. + * + * Let `count` be `min(r.size(), n)`. + * Reads, and advances `r` by `count` characters. + * `r.begin()` is in no point dereferenced. + * If `r.size()` is not defined, the range is not contiguous, and an empty + * span is returned. + * + * \return A `span` pointing to `r`, starting from `r.begin()` and with a + * size of `count`. + * If `r.begin() == r.end()`, returns EOF. + * If the range does not satisfy `contiguous_range`, returns an empty + * `span`. + */ + template <typename WrappedRange, + typename std::enable_if< + WrappedRange::provides_buffer_access>::type* = nullptr> + expected<span<const typename detail::extract_char_type< + typename WrappedRange::iterator>::type>> + read_zero_copy(WrappedRange& r, ranges::range_difference_t<WrappedRange> n) + { + if (r.begin() == r.end()) { + return error(error::end_of_range, "EOF"); + } + return r.get_buffer_and_advance(static_cast<size_t>(n)); + } + template <typename WrappedRange, + typename std::enable_if< + !WrappedRange::provides_buffer_access>::type* = nullptr> + expected<span<const typename detail::extract_char_type< + typename WrappedRange::iterator>::type>> + read_zero_copy(WrappedRange& r, ranges::range_difference_t<WrappedRange>) + { + if (r.begin() == r.end()) { + return error(error::end_of_range, "EOF"); + } + return span<const typename detail::extract_char_type< + typename WrappedRange::iterator>::type>{}; + } + /// @} + + // read_all_zero_copy + + /// @{ + /** + * Reads every character from `r`, as if by repeatedly incrementing + * `r.begin()`, and returns a `span` pointing into `r`. + * + * If there's no error, `r` is advanced to the end. + * `r.begin()` is in no point dereferenced. + * If `r.size()` is not defined, the range is not contiguous, and an empty + * span is returned. + * + * \return A `span` pointing to `r`, starting at `r.begin()` and ending at + * `r.end()`. + * If `r.begin() == r.end()`, returns EOF. + * If the range does not satisfy `contiguous_range`, returns an empty + * `span`. + */ + template < + typename WrappedRange, + typename std::enable_if<WrappedRange::is_contiguous>::type* = nullptr> + expected<span<const typename detail::extract_char_type< + typename WrappedRange::iterator>::type>> + read_all_zero_copy(WrappedRange& r) + { + if (r.begin() == r.end()) { + return error(error::end_of_range, "EOF"); + } + auto s = make_span(r.data(), static_cast<size_t>(r.size())); + r.advance(r.size()); + return s; + } + template < + typename WrappedRange, + typename std::enable_if<!WrappedRange::is_contiguous>::type* = nullptr> + expected<span<const typename detail::extract_char_type< + typename WrappedRange::iterator>::type>> + read_all_zero_copy(WrappedRange& r) + { + if (r.begin() == r.end()) { + return error(error::end_of_range, "EOF"); + } + return span<const typename detail::extract_char_type< + typename WrappedRange::iterator>::type>{}; + } + /// @} + + // read_into + + namespace detail { + template <typename WrappedRange, typename OutputIterator> + error read_into_impl(WrappedRange& r, + OutputIterator& it, + ranges::range_difference_t<WrappedRange> n) + { + for (; n != 0; --n) { + auto ret = read_code_unit(r, false); + if (!ret) { + return ret.error(); + } + *it = ret.value(); + r.advance(); + } + return {}; + } + } // namespace detail + + /// @{ + + /** + * Reads up to `n` characters (= code units) from `r`, as if by repeatedly + * calling `read_code_unit()`, and writing the characters into `it`. + * + * If reading fails at any point, the error is returned. + * `r` is advanced by as many characters that were successfully read. + * + * \param r Range to read + * \param it Iterator to write into, e.g. `std::back_insert_iterator`. Must + * satisfy `output_iterator`, and be incrementable by `n` times. + * \param n Characters to read from `r` + * + * \return `error::good` if `n` characters were read. + * If `r.begin() == r.end()` at any point before `n` characters has been + * read, returns EOF. + * Any error returned by `read_code_unit()` if one + * occurred. + */ + template <typename WrappedRange, + typename OutputIterator, + typename std::enable_if< + WrappedRange::provides_buffer_access>::type* = nullptr> + error read_into(WrappedRange& r, + OutputIterator& it, + ranges::range_difference_t<WrappedRange> n) + { + while (n != 0) { + if (r.begin() == r.end()) { + return {error::end_of_range, "EOF"}; + } + auto s = read_zero_copy(r, n); + if (!s) { + return s.error(); + } + if (s.value().size() == 0) { + break; + } + it = std::copy(s.value().begin(), s.value().end(), it); + n -= s.value().ssize(); + } + if (n != 0) { + return detail::read_into_impl(r, it, n); + } + return {}; + } + template <typename WrappedRange, + typename OutputIterator, + typename std::enable_if< + !WrappedRange::provides_buffer_access>::type* = nullptr> + error read_into(WrappedRange& r, + OutputIterator& it, + ranges::range_difference_t<WrappedRange> n) + { + if (r.begin() == r.end()) { + return {error::end_of_range, "EOF"}; + } + return detail::read_into_impl(r, it, n); + } + /// @} + + namespace detail { + template <typename WrappedRange, typename Predicate> + expected<span<const typename WrappedRange::char_type>> + read_until_pred_contiguous(WrappedRange& r, + Predicate&& pred, + bool pred_result_to_stop, + bool keep_final) + { + using span_type = span<const typename WrappedRange::char_type>; + + if (r.begin() == r.end()) { + return error(error::end_of_range, "EOF"); + } + + if (!pred.is_multibyte()) { + for (auto it = r.begin(); it != r.end(); ++it) { + if (pred(make_span(&*it, 1)) == pred_result_to_stop) { + auto begin = r.data(); + auto end = keep_final ? it + 1 : it; + r.advance_to(end); + return span_type{ + begin, to_address_safe(end, r.begin(), r.end())}; + } + } + } + else { + for (auto it = r.begin(); it != r.end();) { + auto len = ::scn::get_sequence_length(*it); + if (len == 0 || ranges::distance(it, r.end()) < len) { + return error{error::invalid_encoding, + "Invalid code point"}; + } + auto span = + make_span(to_address_safe(it, r.begin(), r.end()), + static_cast<size_t>(len)); + code_point cp{}; + auto i = parse_code_point(span.begin(), span.end(), cp); + if (!i) { + return i.error(); + } + if (i.value() != span.end()) { + return error{error::invalid_encoding, + "Invalid code point"}; + } + if (pred(span) == pred_result_to_stop) { + auto begin = r.data(); + auto end = keep_final ? it + len : it; + r.advance_to(end); + return span_type{ + begin, to_address_safe(end, r.begin(), r.end())}; + } + it += len; + } + } + auto begin = r.data(); + auto end = r.data() + r.size(); + r.advance_to(r.end()); + return span_type{begin, end}; + } + } // namespace detail + + // read_until_space_zero_copy + + namespace detail { + template <typename WrappedRange, typename Predicate> + expected<span<const typename WrappedRange::char_type>> + read_until_space_zero_copy_impl(WrappedRange& r, + Predicate&& is_space, + bool keep_final_space, + std::true_type) + { + return detail::read_until_pred_contiguous(r, SCN_FWD(is_space), + true, keep_final_space); + } + template <typename WrappedRange, typename Predicate> + expected<span<const typename WrappedRange::char_type>> + read_until_space_zero_copy_impl(WrappedRange& r, + Predicate&&, + bool, + std::false_type) + { + if (r.begin() == r.end()) { + return error(error::end_of_range, "EOF"); + } + return span<const typename WrappedRange::char_type>{}; + } + } // namespace detail + + /** + * Reads code points from `r`, until a space, as determined by `is_space`, + * is found, and returns a `span` pointing to `r`. + * + * If no error occurs `r` is advanced past the returned span. + * On error, `r` is not advanced. + * + * \param r Range to read from + * + * \param is_space Predicate taking a span of code units encompassing a code + * point, and returning a `bool`, where `true` means that the character is a + * space. Additionally, it must have a member function + * `is_space.is_multibyte()`, returning a `bool`, where `true` means that a + * space character can encompass multiple code units. + * + * \param keep_final_space If `true`, the space code point found is included + * in the returned span, and it is advanced past in `r`. If `false`, it is + * not included, and `r.begin()` will point to the space. + * + * \return Span of code units, pointing to `r`, starting at `r.begin()`, and + * ending at the space character, the precise location determined by the + * `keep_final_space` parameter. + * If `r.begin() == r.end()`, returns EOF. + * `r` reaching its end before a space character is found is not considered + * an error. + * If `r` contains invalid encoding, returns `error::invalid_encoding`. + * If the range is not contiguous, returns an empty `span`. + */ + template <typename WrappedRange, typename Predicate> + expected<span<const typename WrappedRange::char_type>> + read_until_space_zero_copy(WrappedRange& r, + Predicate&& is_space, + bool keep_final_space) + { + return detail::read_until_space_zero_copy_impl( + r, SCN_FWD(is_space), keep_final_space, + std::integral_constant<bool, WrappedRange::is_contiguous>{}); + } + + // read_until_space + + namespace detail { + template <typename WrappedRange, + typename Predicate, + typename OutputIt, + typename OutputItCmp> + error read_until_pred_buffer(WrappedRange& r, + Predicate&& pred, + bool pred_result_to_stop, + OutputIt& out, + OutputItCmp out_cmp, + bool keep_final, + bool& done, + std::true_type) + { + if (!pred.is_multibyte()) { + while (r.begin() != r.end() && !done) { + auto s = r.get_buffer_and_advance(); + for (auto it = s.begin(); it != s.end() && out_cmp(out); + ++it) { + if (pred(make_span(&*it, 1)) == pred_result_to_stop) { + if (keep_final) { + *out = *it; + ++out; + } + auto e = + putback_n(r, ranges::distance(it, s.end())); + if (!e) { + return e; + } + done = true; + break; + } + *out = *it; + ++out; + } + if (!done && out_cmp(out)) { + auto ret = read_code_unit(r, false); + if (!ret) { + if (ret.error() == error::end_of_range) { + return {}; + } + return ret.error(); + } + if (pred(make_span(&ret.value(), 1)) == + pred_result_to_stop) { + if (keep_final) { + r.advance(); + *out = ret.value(); + ++out; + } + done = true; + break; + } + r.advance(); + *out = ret.value(); + ++out; + } + } + } + else { + while (r.begin() != r.end() && !done) { + auto s = r.get_buffer_and_advance(); + for (auto it = s.begin(); it != s.end() && out_cmp(out);) { + auto len = ::scn::get_sequence_length(*it); + if (len == 0) { + return error{error::invalid_encoding, + "Invalid code point"}; + } + if (ranges::distance(it, s.end()) < len) { + auto e = putback_n(r, len); + if (!e) { + return e; + } + break; + } + auto cpspan = make_span(it, static_cast<size_t>(len)); + code_point cp{}; + auto i = + parse_code_point(cpspan.begin(), cpspan.end(), cp); + if (!i) { + return i.error(); + } + if (i.value() != cpspan.end()) { + return error{error::invalid_encoding, + "Invalid code point"}; + } + if (pred(cpspan) == pred_result_to_stop) { + if (keep_final) { + out = std::copy(cpspan.begin(), cpspan.end(), + out); + } + done = true; + break; + } + out = std::copy(cpspan.begin(), cpspan.end(), out); + } + + if (!done && out_cmp(out)) { + alignas(typename WrappedRange::char_type) unsigned char + buf[4] = {0}; + auto cpret = read_code_point(r, make_span(buf, 4)); + if (!cpret) { + if (cpret.error() == error::end_of_range) { + return {}; + } + return cpret.error(); + } + if (pred(cpret.value().chars) == pred_result_to_stop) { + if (keep_final) { + out = std::copy(cpret.value().chars.begin(), + cpret.value().chars.end(), out); + } + else { + return putback_n(r, + cpret.value().chars.ssize()); + } + done = true; + break; + } + out = std::copy(cpret.value().chars.begin(), + cpret.value().chars.end(), out); + } + } + } + return {}; + } + template <typename WrappedRange, + typename Predicate, + typename OutputIt, + typename OutputItCmp> + error read_until_pred_buffer(WrappedRange&, + Predicate&&, + bool, + OutputIt&, + OutputItCmp, + bool, + bool& done, + std::false_type) + { + done = false; + return {}; + } + + template <typename WrappedRange, + typename Predicate, + typename OutputIt, + typename OutputItCmp> + error read_until_pred_non_contiguous(WrappedRange& r, + Predicate&& pred, + bool pred_result_to_stop, + OutputIt& out, + OutputItCmp out_cmp, + bool keep_final) + { + if (r.begin() == r.end()) { + return {error::end_of_range, "EOF"}; + } + + { + bool done = false; + auto e = read_until_pred_buffer( + r, pred, pred_result_to_stop, out, out_cmp, keep_final, + done, + std::integral_constant< + bool, WrappedRange::provides_buffer_access>{}); + if (!e) { + return e; + } + if (done) { + return {}; + } + } + + if (!pred.is_multibyte()) { + while (r.begin() != r.end() && out_cmp(out)) { + auto cu = read_code_unit(r, false); + if (!cu) { + return cu.error(); + } + if (pred(make_span(&cu.value(), 1)) == + pred_result_to_stop) { + if (keep_final) { + r.advance(); + *out = cu.value(); + ++out; + } + return {}; + } + r.advance(); + *out = cu.value(); + ++out; + } + } + else { + unsigned char buf[4] = {0}; + while (r.begin() != r.end() && out_cmp(out)) { + auto cp = read_code_point(r, make_span(buf, 4)); + if (!cp) { + return cp.error(); + } + if (pred(cp.value().chars) == pred_result_to_stop) { + if (keep_final) { + out = std::copy(cp.value().chars.begin(), + cp.value().chars.end(), out); + return {}; + } + else { + return putback_n(r, cp.value().chars.ssize()); + } + } + out = std::copy(cp.value().chars.begin(), + cp.value().chars.end(), out); + } + } + return {}; + } + } // namespace detail + + /// @{ + + /** + * Reads code points from `r`, until a space, as determined by `is_space`, + * is found, and writes them into `out`, a single code unit at a time. + * + * If no error occurs, `r` is advanced past the last character written into + * `out`. + * + * On error, `r` is advanced an indeterminate amount, as if by calling + * `r.advance(n)`, where `n` is a non-negative integer. + * It is, however, not advanced past any space characters. + * + * \param r Range to read from + * + * \param out Iterator to write read characters into. Must satisfy + * `output_iterator`. + * + * \param is_space Predicate taking a span of code units encompassing a code + * point, and returning a `bool`, where `true` means that the character is a + * space. Additionally, it must have a member function + * `is_space.is_multibyte()`, returning a `bool`, where `true` means that a + * space character can encompass multiple code units. + * + * \param keep_final_space If `true`, the space code point found is written + * into `out`, and it is advanced past in `r`. If `false`, it is not + * included, and `r.begin()` will point to the space. + * + * \return `error::good` on success. + * If `r.begin() == r.end()`, returns EOF. + * `r` reaching its end before a space character is found is not considered + * an error. + * If `r` contains invalid encoding, returns `error::invalid_encoding`. + */ + template < + typename WrappedRange, + typename OutputIterator, + typename Predicate, + typename std::enable_if<WrappedRange::is_contiguous>::type* = nullptr> + error read_until_space(WrappedRange& r, + OutputIterator& out, + Predicate&& is_space, + bool keep_final_space) + { + auto s = + read_until_space_zero_copy(r, SCN_FWD(is_space), keep_final_space); + if (!s) { + return s.error(); + } + out = std::copy(s.value().begin(), s.value().end(), out); + return {}; + } + template < + typename WrappedRange, + typename OutputIterator, + typename Predicate, + typename std::enable_if<!WrappedRange::is_contiguous>::type* = nullptr> + error read_until_space(WrappedRange& r, + OutputIterator& out, + Predicate&& is_space, + bool keep_final_space) + { + return detail::read_until_pred_non_contiguous( + r, SCN_FWD(is_space), true, out, + [](const OutputIterator&) { return true; }, keep_final_space); + } + + /// @} + + // read_until_space_ranged + + /// @{ + + /** + * Otherwise equivalent to `read_until_space`, except will also stop reading + * if `out == end`. + * + * \see read_until_space + */ + template <typename WrappedRange, + typename OutputIterator, + typename Sentinel, + typename Predicate> + error read_until_space_ranged(WrappedRange& r, + OutputIterator& out, + Sentinel end, + Predicate&& is_space, + bool keep_final_space) + { + return detail::read_until_pred_non_contiguous( + r, SCN_FWD(is_space), true, out, + [&end](const OutputIterator& it) { return it != end; }, + keep_final_space); + } + + /// @} + + namespace detail { + /** + * Predicate to pass to read_until_space etc. + */ + template <typename CharT> + struct is_space_predicate { + using char_type = CharT; + using locale_type = basic_locale_ref<char_type>; + + /** + * \param l Locale to use, fetched from `ctx.locale()` + * \param localized If `true`, use `l.get_custom()`, otherwise use + * `l.get_static()`. + * \param width If `width != 0`, limit the number of code + * units to be read + */ + SCN_CONSTEXPR14 is_space_predicate(const locale_type& l, + bool localized, + size_t width) + : m_locale{nullptr}, + m_width{width}, + m_fn{get_fn(localized, width != 0)} + { + if (localized) { + l.prepare_localized(); + m_locale = l.get_localized_unsafe(); + } + } + + /** + * Returns `true` if `ch` is a code point according to the supplied + * locale, using either the static or custom locale, depending on + * the `localized` parameter given to the constructor. + * + * Returns also `true` if the maximum width, as determined by the + * `width` parameter given to the constructor, was reached. + */ + bool operator()(span<const char_type> ch) + { + SCN_EXPECT(m_fn); + SCN_EXPECT(ch.size() >= 1); + return m_fn(m_locale, ch, m_i, m_width); + } + + /** + * Returns `true`, if `*this` uses the custom locale for classifying + * space characters + */ + constexpr bool is_localized() const + { + return m_locale != nullptr; + } + /** + * Returns `true` if a space character can encompass multiple code + * units + */ + constexpr bool is_multibyte() const + { + return is_localized() && is_multichar_type(CharT{}); + } + + private: + using static_locale_type = typename locale_type::static_type; + using custom_locale_type = typename locale_type::custom_type; + const custom_locale_type* m_locale; + size_t m_width{0}, m_i{0}; + + constexpr static bool call(const custom_locale_type*, + span<const char_type> ch, + size_t&, + size_t) + { + return static_locale_type::is_space(ch); + } + static bool localized_call(const custom_locale_type* locale, + span<const char_type> ch, + size_t&, + size_t) + { + SCN_EXPECT(locale != nullptr); + return locale->is_space(ch); + } + SCN_CONSTEXPR14 static bool call_counting(const custom_locale_type*, + span<const char_type> ch, + size_t& i, + size_t max) + { + SCN_EXPECT(i <= max); + if (i == max || i + ch.size() > max) { + return true; + } + i += ch.size(); + return static_locale_type::is_space(ch); + } + static bool localized_call_counting( + const custom_locale_type* locale, + span<const char_type> ch, + size_t& i, + size_t max) + { + SCN_EXPECT(locale != nullptr); + SCN_EXPECT(i <= max); + if (i == max || i + ch.size() > max) { + return true; + } + i += ch.size(); + return locale->is_space(ch); + } + + using fn_type = bool (*)(const custom_locale_type*, + span<const char_type>, + size_t&, + size_t); + fn_type m_fn{nullptr}; + + static SCN_CONSTEXPR14 fn_type get_fn(bool localized, bool counting) + { + if (localized) { + return counting ? localized_call_counting : localized_call; + } + return counting ? call_counting : call; + } + }; + + template <typename CharT> + is_space_predicate<CharT> make_is_space_predicate( + const basic_locale_ref<CharT>& locale, + bool localized, + size_t width = 0) + { + return {locale, localized, width}; + } + + template <typename CharT> + struct basic_skipws_iterator { + using value_type = void; + using reference = void; + using pointer = void; + using size_type = size_t; + using difference_type = std::ptrdiff_t; + using iterator_category = std::output_iterator_tag; + + constexpr basic_skipws_iterator() = default; + + basic_skipws_iterator& operator=(CharT) + { + return *this; + } + basic_skipws_iterator& operator*() + { + return *this; + } + basic_skipws_iterator& operator++() + { + return *this; + } + }; + } // namespace detail + + // skip_range_whitespace + + /// @{ + + /** + * Reads code points from `ctx.range()`, as if by repeatedly calling + * `read_code_point()`, until a non-space character is found, or EOF is + * reached. That non-space character is then put back into the range. + * + * Whether a character is a space, is determined by `ctx.locale()` and the + * `localized` parameter. + * + * \param ctx Context to get the range and locale from. + * + * \param localized If `true`, `ctx.locale().get_custom()` is used. + * Otherwise, `ctx.locale().get_static()` is used. + * In practice, means whether locale-specific whitespace characters are + * accepted, or just those given by `std::isspace` with the `"C"` locale. + * + * \return `error::good` on success. + * If `ctx.range().begin() == ctx.range().end()`, returns EOF. + * If `ctx.range()` contains invalid encoding, returns + * `error::invalid_encoding`. + */ + template <typename Context, + typename std::enable_if< + !Context::range_type::is_contiguous>::type* = nullptr> + error skip_range_whitespace(Context& ctx, bool localized) noexcept + { + auto is_space_pred = + detail::make_is_space_predicate(ctx.locale(), localized); + auto it = detail::basic_skipws_iterator<typename Context::char_type>{}; + return detail::read_until_pred_non_contiguous( + ctx.range(), is_space_pred, false, it, + [](decltype(it)) { return true; }, false); + } + template <typename Context, + typename std::enable_if< + Context::range_type::is_contiguous>::type* = nullptr> + error skip_range_whitespace(Context& ctx, bool localized) noexcept + { + auto is_space_pred = + detail::make_is_space_predicate(ctx.locale(), localized); + return detail::read_until_pred_contiguous(ctx.range(), is_space_pred, + false, false) + .error(); + } + + /// @} + + namespace detail { + template <typename T> + struct simple_integer_scanner { + template <typename CharT> + static expected<typename span<const CharT>::iterator> scan( + span<const CharT> buf, + T& val, + int base = 10, + uint16_t flags = 0); + + template <typename CharT> + static expected<typename span<const CharT>::iterator> scan_lower( + span<const CharT> buf, + T& val, + int base = 10, + uint16_t flags = 0); + }; + } // namespace detail + + /** + * A very simple parser base class, which only accepts empty format string + * specifiers, e.g. `{}`, `{:}` or `{1:}`. + */ + struct empty_parser : parser_base { + template <typename ParseCtx> + error parse(ParseCtx& pctx) + { + pctx.arg_begin(); + if (SCN_UNLIKELY(!pctx)) { + return {error::invalid_format_string, + "Unexpected format string end"}; + } + if (!pctx.check_arg_end()) { + return {error::invalid_format_string, "Expected argument end"}; + } + pctx.arg_end(); + return {}; + } + }; + + /** + * Provides a framework for building a format string parser. + * Does not provide a `parse()` member function, so not a parser on to its + * own. + */ + struct common_parser : parser_base { + static constexpr bool support_align_and_fill() + { + return true; + } + + protected: + /** + * Parse the beginning of the argument. + * Returns `error::invalid_format_string` if `!pctx` (the format string + * ended) + */ + template <typename ParseCtx> + error parse_common_begin(ParseCtx& pctx) + { + pctx.arg_begin(); + if (SCN_UNLIKELY(!pctx)) { + return {error::invalid_format_string, + "Unexpected format string end"}; + } + return {}; + } + + /** + * Returns `error::invalid_format_string` if the format string or the + * argument has ended. + */ + template <typename ParseCtx> + error check_end(ParseCtx& pctx) + { + if (!pctx || pctx.check_arg_end()) { + return {error::invalid_format_string, + "Unexpected end of format string argument"}; + } + return {}; + } + + /** + * Parse alignment, fill, width, and localization flags, and populate + * appropriate member variables. + * + * Returns `error::invalid_format_string` if an error occurred. + */ + template <typename ParseCtx> + error parse_common_flags(ParseCtx& pctx) + { + SCN_EXPECT(check_end(pctx)); + using char_type = typename ParseCtx::char_type; + + auto ch = pctx.next_char(); + auto next_char = [&]() -> error { + pctx.advance_char(); + auto e = check_end(pctx); + if (!e) { + return e; + } + ch = pctx.next_char(); + return {}; + }; + auto parse_number = [&](size_t& n) -> error { + SCN_EXPECT(pctx.locale().get_static().is_digit(ch)); + + auto it = pctx.begin(); + for (; it != pctx.end(); ++it) { + if (!pctx.locale().get_static().is_digit(*it)) { + break; + } + } + auto buf = make_span(pctx.begin(), it); + + auto s = detail::simple_integer_scanner<size_t>{}; + auto res = s.scan(buf, n, 10); + if (!res) { + return res.error(); + } + + for (it = pctx.begin(); it != res.value(); + pctx.advance_char(), it = pctx.begin()) {} + return {}; + }; + + auto get_align_char = [&](char_type c) -> common_options_type { + if (c == detail::ascii_widen<char_type>('<')) { + return aligned_left; + } + if (c == detail::ascii_widen<char_type>('>')) { + return aligned_right; + } + if (c == detail::ascii_widen<char_type>('^')) { + return aligned_center; + } + return common_options_none; + }; + auto parse_align = [&](common_options_type align, char_type fill) { + if (align != common_options_none) { + common_options |= align; + } + fill_char = static_cast<char32_t>(fill); + }; + + // align and fill + common_options_type align{}; + bool align_set = false; + if (pctx.chars_left() > 1 && + ch != detail::ascii_widen<char_type>('[')) { + const auto peek = pctx.peek_char(); + align = get_align_char(peek); + if (align != common_options_none) { + // Arg is like "{:_x}", where _ is some fill character, and + // x is an alignment flag + // -> we have both alignment and fill + parse_align(align, ch); + + auto e = next_char(); + SCN_ENSURE(e); + if (!next_char()) { + return {}; + } + align_set = true; + } + } + if (!align_set) { + align = get_align_char(ch); + if (align != common_options_none) { + // Arg is like "{:x}", where x is an alignment flag + // -> we have alignment with default fill (space ' ') + parse_align(align, detail::ascii_widen<char_type>(' ')); + if (!next_char()) { + return {}; + } + } + } + + // digit -> width + if (pctx.locale().get_static().is_digit(ch)) { + common_options |= width_set; + + size_t w{}; + auto e = parse_number(w); + if (!e) { + return e; + } + field_width = w; + return {}; + } + // L -> localized + if (ch == detail::ascii_widen<char_type>('L')) { + common_options |= localized; + + if (!next_char()) { + return {}; + } + } + + return {}; + } + + /** + * Parse argument end. + * + * Returns `error::invalid_format_string` if argument end was not found. + */ + template <typename ParseCtx> + error parse_common_end(ParseCtx& pctx) + { + if (!pctx || !pctx.check_arg_end()) { + return {error::invalid_format_string, "Expected argument end"}; + } + + pctx.arg_end(); + return {}; + } + + /** + * A null callback to pass to `parse_common`, doing nothing and + * returning `error::good`. + */ + template <typename ParseCtx> + static error null_type_cb(ParseCtx&, bool&) + { + return {}; + } + + public: + /** + * Parse a format string argument, using `parse_common_begin`, + * `parse_common_flags`, `parse_common_end`, and the supplied type + * flags. + * + * `type_options.size() == type_flags.size()` must be `true`. + * `pctx` must be valid, and must start at the format string argument + * specifiers, e.g. in the case of `"{1:foo}"` -> `pctx == "foo}"` + * + * \param pctx Format string to parse + * \param type_options A span of characters, where each character + * corresponds to a valid type flag. For example, for characters, this + * span would be \c ['c'] + * \param type_flags A span of bools, where the values will be set to + * `true`, if a corresponding type flag from `type_options` was found. + * Should be initialized to all-`false`, as a `false` value will not be + * written. + * \param type_cb A callback to call, if none of the `type_options` + * matched. Must have the signature `(ParseCtx& pctx, bool& parsed) -> + * error`., where `parsed` is set to `true`, if the flag at + * `pctx.next_char()` was parsed and advanced past. + */ + template <typename ParseCtx, + typename F, + typename CharT = typename ParseCtx::char_type> + error parse_common(ParseCtx& pctx, + span<const CharT> type_options, + span<bool> type_flags, + F&& type_cb) + { + SCN_EXPECT(type_options.size() == type_flags.size()); + + auto e = parse_common_begin(pctx); + if (!e) { + return e; + } + + if (!pctx) { + return {error::invalid_format_string, + "Unexpected end of format string"}; + } + if (pctx.check_arg_end()) { + return {}; + } + + e = parse_common_flags(pctx); + if (!e) { + return e; + } + + if (!pctx) { + return {error::invalid_format_string, + "Unexpected end of format string"}; + } + if (pctx.check_arg_end()) { + return {}; + } + + for (auto ch = pctx.next_char(); pctx && !pctx.check_arg_end(); + ch = pctx.next_char()) { + bool parsed = false; + for (std::size_t i = 0; i < type_options.size() && !parsed; + ++i) { + if (ch == type_options[i]) { + if (SCN_UNLIKELY(type_flags[i])) { + return {error::invalid_format_string, + "Repeat flag in format string"}; + } + type_flags[i] = true; + parsed = true; + } + } + if (parsed) { + pctx.advance_char(); + if (!pctx || pctx.check_arg_end()) { + break; + } + continue; + } + + e = type_cb(pctx, parsed); + if (!e) { + return e; + } + if (parsed) { + if (!pctx || pctx.check_arg_end()) { + break; + } + continue; + } + ch = pctx.next_char(); + + if (!parsed) { + return {error::invalid_format_string, + "Invalid character in format string"}; + } + if (!pctx || pctx.check_arg_end()) { + break; + } + } + + return parse_common_end(pctx); + } + + void make_localized() + { + common_options |= localized; + } + + /** + * Invoke `parse_common()` with default options (no type flags) + */ + template <typename ParseCtx> + error parse_default(ParseCtx& pctx) + { + return parse_common(pctx, {}, {}, null_type_cb<ParseCtx>); + } + + constexpr bool is_aligned_left() const noexcept + { + return (common_options & aligned_left) != 0 || + (common_options & aligned_center) != 0; + } + constexpr bool is_aligned_right() const noexcept + { + return (common_options & aligned_right) != 0 || + (common_options & aligned_center) != 0; + } + template <typename CharT> + constexpr CharT get_fill_char() const noexcept + { + return static_cast<CharT>(fill_char); + } + + size_t field_width{0}; + char32_t fill_char{0}; + enum common_options_type : uint8_t { + common_options_none = 0, + localized = 1, // 'L', + aligned_left = 2, // '<' + aligned_right = 4, // '>' + aligned_center = 8, // '^' + width_set = 16, // width + common_options_all = 31, + }; + uint8_t common_options{0}; + }; + + /** + * Derives from `common_parser`, and implements `parse()` with + * `parse_default()` + */ + struct common_parser_default : common_parser { + template <typename ParseCtx> + error parse(ParseCtx& pctx) + { + return parse_default(pctx); + } + }; + + namespace detail { + template <typename Context, + typename std::enable_if< + !Context::range_type::is_contiguous>::type* = nullptr> + error scan_alignment(Context& ctx, + typename Context::char_type fill) noexcept + { + while (true) { + SCN_CLANG_PUSH_IGNORE_UNDEFINED_TEMPLATE + + auto ch = read_code_unit(ctx.range()); + if (SCN_UNLIKELY(!ch)) { + return ch.error(); + } + if (ch.value() != fill) { + auto pb = putback_n(ctx.range(), 1); + if (SCN_UNLIKELY(!pb)) { + return pb; + } + break; + } + + SCN_CLANG_POP_IGNORE_UNDEFINED_TEMPLATE + } + return {}; + } + template <typename Context, + typename std::enable_if< + Context::range_type::is_contiguous>::type* = nullptr> + error scan_alignment(Context& ctx, + typename Context::char_type fill) noexcept + { + SCN_CLANG_PUSH_IGNORE_UNDEFINED_TEMPLATE + const auto end = ctx.range().end(); + for (auto it = ctx.range().begin(); it != end; ++it) { + if (*it != fill) { + ctx.range().advance_to(it); + return {}; + } + } + ctx.range().advance_to(end); + return {}; + + SCN_CLANG_POP_IGNORE_UNDEFINED_TEMPLATE + } + + template <typename Scanner, typename = void> + struct scanner_supports_alignment : std::false_type { + }; + template <typename Scanner> + struct scanner_supports_alignment< + Scanner, + typename std::enable_if<Scanner::support_align_and_fill()>::type> + : std::true_type { + }; + + template <typename Context, typename Scanner> + error skip_alignment(Context& ctx, + Scanner& scanner, + bool left, + std::true_type) + { + if (left && !scanner.is_aligned_left()) { + return {}; + } + if (!left && !scanner.is_aligned_right()) { + return {}; + } + return scan_alignment( + ctx, + scanner.template get_fill_char<typename Context::char_type>()); + } + template <typename Context, typename Scanner> + error skip_alignment(Context&, Scanner&, bool, std::false_type) + { + return {}; + } + + /** + * Scan argument in `val`, from `ctx`, using `Scanner` and `pctx`. + * + * Parses `pctx` for `Scanner`, skips whitespace and alignment if + * necessary, and scans the argument into `val`. + */ + template <typename Scanner, + typename T, + typename Context, + typename ParseCtx> + error visitor_boilerplate(T& val, Context& ctx, ParseCtx& pctx) + { + Scanner scanner; + + auto err = pctx.parse(scanner); + if (!err) { + return err; + } + + if (scanner.skip_preceding_whitespace()) { + err = skip_range_whitespace(ctx, false); + if (!err) { + return err; + } + } + + err = skip_alignment(ctx, scanner, false, + scanner_supports_alignment<Scanner>{}); + if (!err) { + return err; + } + + err = scanner.scan(val, ctx); + if (!err) { + return err; + } + + return skip_alignment(ctx, scanner, true, + scanner_supports_alignment<Scanner>{}); + } + } // namespace detail + + SCN_END_NAMESPACE +} // namespace scn + +#endif |