Niels Lohmann
a47170346a
* docs: new design for the documentation site Apply the brand to the Material for MkDocs site: Inter and JetBrains Mono served by the site (upright and real italic), brand colours, blue header band with the syntax pattern, wordmark in the header, new home page (hero, cards, animated feature tour), 404 page, polish for tabs, search, footer, focus rings, tables and code blocks, and theme features (code copy, previous/next footer, TOC follow, search suggestions). Draw the number railroad diagram, the parser callback events and the iterator illustrations as inline SVGs that follow the light and dark scheme. The generator scripts are in docs/mkdocs/scripts/figures; the feature slideshow (json-light.svg, json-dark.svg, replacing json.gif on the home page) is built by docs/mkdocs/scripts/slideshow. Decision nodes in five flowcharts become hexagons, which need far less room. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * docs: add figures, table captions and a macro chooser - Figures with numbered captions: SAX stepper, json_view layout and edit stepper, exception map, JSON pointer and patch walkers, QA pipeline, scaling and binary size charts, roadmap lanes, release timeline, integration decision tree and namespace builder - Table captions (nj-table-caption) on 9 pages - Compile times: modules and PCH charts, filesystem section, re-measured Figure 1, links between features/modules.md and compile_times.md - Interactive macro chooser for features/arbitrary_types.md - Link check: exclude URLs that answer the plugin with 400/401/419 or are dead (customers.md) Signed-off-by: Niels Lohmann <mail@nlohmann.me> * docs: macro chooser generates adl_serializer for non-default-constructible types Signed-off-by: Niels Lohmann <mail@nlohmann.me> * docs: cross-link concept pages and API pages in See also sections Add See also links in both directions between the concept pages (features, home, integration) and the API pages, write API links in code font, give every entry a comment after a dash, and show the callback event figure on the parser callbacks page. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * docs: address review comments on the new design - Home: add a "Latest release" button - Sponsors: update the list and group it by tier - Features: list all feature pages on the index page - Releases: add highlights per release, link the 4.0 roadmap, add the first commit to the timeline - Exceptions: prefix all example messages with the exception name - API: no code font for format names in the See also links of the to_/from_ pages - Merge Patch: show the document before, the patch, and the result - Replace "--" with typographic dashes, mark external links with an icon, center Mermaid diagrams Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2.6 KiB
2.6 KiB
JSON_HAS_FILESYSTEM / JSON_HAS_EXPERIMENTAL_FILESYSTEM
#define JSON_HAS_FILESYSTEM /* value */
#define JSON_HAS_EXPERIMENTAL_FILESYSTEM /* value */
When compiling with C++17, the library provides conversions from and to
std::filesystem::path. As compiler support for filesystem is
limited, the library tries to detect whether
<filesystem>/std::filesystem (JSON_HAS_FILESYSTEM) or
<experimental/filesystem>/std::experimental::filesystem
(JSON_HAS_EXPERIMENTAL_FILESYSTEM) should be used. To override the built-in check, define JSON_HAS_FILESYSTEM or
JSON_HAS_EXPERIMENTAL_FILESYSTEM to 1.
Default definition
The default value is detected based on the preprocessor macros #!cpp __cpp_lib_filesystem,
#!cpp __cpp_lib_experimental_filesystem, #!cpp __has_include(<filesystem>), or
#!cpp __has_include(<experimental/filesystem>).
!!! info "Known compiler/stdlib exclusions"
Even when the feature-test macro indicates filesystem support is available, the library disables it on the following broken toolchains:
- **MinGW + GCC 8** — disabled entirely (broken `std::filesystem` implementation; [MinGW-w64 bug 737](https://sourceforge.net/p/mingw-w64/bugs/737/))
- **GCC (non-Clang) < 8** — disabled (no filesystem support)
- **Clang < 7** — disabled (no filesystem support)
- **MSVC < 19.14** — disabled (no filesystem support)
- **iOS < 13** — disabled (no filesystem support)
- **macOS < Catalina (10.15)** — disabled (no filesystem support)
If `JSON_HAS_FILESYSTEM` or `JSON_HAS_EXPERIMENTAL_FILESYSTEM` is `0` despite `__cpp_lib_filesystem` being defined, one
of the exclusions above likely applies to your toolchain.
Notes
- Note that older compilers or older versions of libstdc++ also require the library
stdc++fsto be linked to for filesystem support. - Both macros are undefined outside the library.
Examples
??? example
The code below forces the library to use the header `<experimental/filesystem>`.
```cpp
#define JSON_HAS_EXPERIMENTAL_FILESYSTEM 1
#include <nlohmann/json.hpp>
...
```
See also
JSON_HAS_CPP_11/JSON_HAS_CPP_14/JSON_HAS_CPP_17/JSON_HAS_CPP_20/JSON_HAS_CPP_23/JSON_HAS_CPP_26- set supported C++ standard- Supported Macros - guide to all supported macros
- Converting values - conversions of values
Version history
- Added in version 3.10.5.