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json/tests/src/test_utils.hpp
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Niels LohmannandGitHub ca76c37650 Add iterator+sentinel tests and docs for binary deserializers (#5265)
* Add iterator+sentinel tests and docs for binary deserializers

This commit extends the C++20 ranges support (iterator+sentinel pairs) to the
binary format deserializers from_cbor, from_msgpack, from_ubjson, from_bjdata,
and from_bson, matching what was already done for parse(), accept(), and
sax_parse().

Changes:
- Add istreambuf_sentinel helper to test_utils.hpp for EOF detection in tests
- Add 5 new test cases that read binary files directly via
  std::istreambuf_iterator<char> + sentinel, without pre-buffering
- Update documentation for all 5 from_* functions to document overload (3)
  with SentinelType parameter
- All tests pass; verified against existing test suite data
- Fix potential buffer over-read warning in heterogeneous iterator test

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Merge iterator+sentinel overloads and fix ambiguity/CI issues

Address PR review feedback and CI failures:

- Merge the separate same-type and sentinel-type iterator overloads of
  parse(), accept(), sax_parse(), and the five from_* binary deserializers
  into a single overload with SentinelType defaulted to IteratorType,
  as suggested in review. Applied the same simplification to the
  detail::input_adapter() free functions.
- Fix a latent ambiguity: some compilers (e.g. GCC 4.8) unreliably SFINAE
  the operator!= detection for std::nullptr_t against container/string
  types, making calls like parse(s, nullptr, ...) ambiguous with the
  compatible-input overload. can_compare_ne now explicitly excludes
  std::nullptr_t as a SentinelType.
- Use a named enable_if_t template parameter instead of an unnamed
  function parameter for the SFINAE guard, fixing a clang-tidy
  hicpp-named-parameter/readability-named-parameter failure.
- Update parse.md, accept.md, sax_parse.md, and the five from_*.md pages
  to document the merged overload instead of separate (2)/(3) overloads,
  also fixing an over-160-char line that broke the documentation
  style_check CI job.
- Rework the BSON iterator+sentinel test to parse a BSON file already
  present in the test suite instead of writing/deleting a temp file.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Fix -Wunneeded-internal-declaration for CustomSentinel in test

CustomSentinel lives in an anonymous namespace (internal linkage), and
the library's parse loop only ever evaluates the iterator-first
direction (it != last), so the reversed-order friend operator!= was
never referenced. Clang's -Weverything flags such unused internal
declarations as an error. Drop the unused overload; the used direction
is enough to satisfy can_compare_ne's either-order detection.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Fix clang-tidy hicpp-named-parameter and misc-const-correctness

- Drop the unused reversed-order operator!= overload from
  utils::istreambuf_sentinel (only iterator != sentinel is ever
  evaluated) and name the remaining friend's sentinel parameter, fixing
  hicpp-named-parameter/readability-named-parameter.
- Mark the istreambuf_iterator first/last helper variable const in the
  five binary-format sentinel tests, fixing misc-const-correctness.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Fix clang-tidy misc-const-correctness in heterogeneous sentinel test

json_str is only read via .data()/.size() and never reassigned, so
clang-tidy correctly flags it as const-able. Verified against the exact
CI job (silkeh/clang:dev, ci_clang_tidy target) by running clang-tidy
directly on this file plus the five binary-format sentinel tests
touched by prior commits; all are now clean.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-07-11 15:09:28 +02:00

47 lines
1.5 KiB
C++

// __ _____ _____ _____
// __| | __| | | | JSON for Modern C++ (supporting code)
// | | |__ | | | | | | version 3.12.0
// |_____|_____|_____|_|___| https://github.com/nlohmann/json
//
// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
// SPDX-License-Identifier: MIT
#pragma once
#include <cstdint> // uint8_t
#include <fstream> // ifstream, istreambuf_iterator, ios
#include <vector> // vector
namespace utils
{
inline std::vector<std::uint8_t> read_binary_file(const std::string& filename)
{
std::ifstream file(filename, std::ios::binary);
file.unsetf(std::ios::skipws);
file.seekg(0, std::ios::end);
const auto size = file.tellg();
file.seekg(0, std::ios::beg);
std::vector<std::uint8_t> byte_vector;
byte_vector.reserve(static_cast<std::size_t>(size));
byte_vector.insert(byte_vector.begin(), std::istream_iterator<std::uint8_t>(file), std::istream_iterator<std::uint8_t>());
return byte_vector;
}
// sentinel for istreambuf_iterator; compares != true until EOF is reached
// lets tests read a file directly via the new iterator+sentinel overloads
// instead of buffering the whole file into a vector first.
// Only the iterator-first direction (it != sentinel) is ever evaluated by
// the library's parse loop, so no reversed-order overload is needed.
struct istreambuf_sentinel
{
friend bool operator!=(const std::istreambuf_iterator<char>& it, const istreambuf_sentinel& /*unused*/) noexcept
{
return it != std::istreambuf_iterator<char>();
}
};
} // namespace utils