5.8 KiB
JsonCpp
JSON is a lightweight data-interchange format. It can represent numbers, strings, ordered sequences of values, and collections of name/value pairs.
JsonCpp is a C++ library that allows manipulating JSON values, including serialization and deserialization to and from strings. It can also preserve existing comment in unserialization/serialization steps, making it a convenient format to store user input files.
Documentation
JsonCpp documentation is generated using Doxygen.
A note on backward-compatibility
1.y.z
is built with C++11.0.y.z
can be used with older compilers.- Major versions maintain binary-compatibility.
Contributing to JsonCpp
Building and testing with Meson/Ninja
Thanks to David Seifert (@SoapGentoo), we (the maintainers) now use meson and ninja to build for debugging, as well as for continuous integration (see travis.sh
). Other systems may work, but minor things like version strings might break.
First, install both meson (which requires Python3) and ninja. If you wish to install to a directory other than /usr/local, set an environment variable called DESTDIR with the desired path: DESTDIR=/path/to/install/dir
Then,
cd jsoncpp/
BUILD_TYPE=debug
#BUILD_TYPE=release
LIB_TYPE=shared
#LIB_TYPE=static
meson --buildtype ${BUILD_TYPE} --default-library ${LIB_TYPE} . build-${LIB_TYPE}
ninja -v -C build-${LIB_TYPE} test
cd build-${LIB_TYPE}
sudo ninja install
Building and testing with other build systems
See https://github.com/open-source-parsers/jsoncpp/wiki/Building
Running the tests manually
You need to run tests manually only if you are troubleshooting an issue.
In the instructions below, replace path/to/jsontest
with the path of the
jsontest
executable that was compiled on your platform.
cd test
# This will run the Reader/Writer tests
python runjsontests.py path/to/jsontest
# This will run the Reader/Writer tests, using JSONChecker test suite
# (http://www.json.org/JSON_checker/).
# Notes: not all tests pass: JsonCpp is too lenient (for example,
# it allows an integer to start with '0'). The goal is to improve
# strict mode parsing to get all tests to pass.
python runjsontests.py --with-json-checker path/to/jsontest
# This will run the unit tests (mostly Value)
python rununittests.py path/to/test_lib_json
# You can run the tests using valgrind:
python rununittests.py --valgrind path/to/test_lib_json
Building the documentation
Run the Python script doxybuild.py
from the top directory:
python doxybuild.py --doxygen=$(which doxygen) --open --with-dot
See doxybuild.py --help
for options.
Adding a reader/writer test
To add a test, you need to create two files in test/data:
- a
TESTNAME.json
file, that contains the input document in JSON format. - a
TESTNAME.expected
file, that contains a flatened representation of the input document.
The TESTNAME.expected
file format is as follows:
- Each line represents a JSON element of the element tree represented by the input document.
- Each line has two parts: the path to access the element separated from the
element value by
=
. Array and object values are always empty (i.e. represented by either[]
or{}
). - Element path
.
represents the root element, and is used to separate object members.[N]
is used to specify the value of an array element at indexN
.
See the examples test_complex_01.json
and test_complex_01.expected
to better understand element paths.
Understanding reader/writer test output
When a test is run, output files are generated beside the input test files. Below is a short description of the content of each file:
test_complex_01.json
: input JSON document.test_complex_01.expected
: flattened JSON element tree used to check if parsing was corrected.test_complex_01.actual
: flattened JSON element tree produced byjsontest
from readingtest_complex_01.json
.test_complex_01.rewrite
: JSON document written byjsontest
using theJson::Value
parsed fromtest_complex_01.json
and serialized usingJson::StyledWritter
.test_complex_01.actual-rewrite
: flattened JSON element tree produced byjsontest
from readingtest_complex_01.rewrite
.test_complex_01.process-output
:jsontest
output, typically useful for understanding parsing errors.
Using JsonCpp in your project
Amalgamated source
https://github.com/open-source-parsers/jsoncpp/wiki/Amalgamated
Other ways
If you have trouble, see the Wiki, or post a question as an Issue.
License
See the LICENSE
file for details. In summary, JsonCpp is licensed under the
MIT license, or public domain if desired and recognized in your jurisdiction.