libgraphqlparser
libgraphqlparser is a parser for
GraphQL, a query language for describing data
requirements on complex application data models, implemented in C++11.
It can be used on its own in C++ code (or in C code via the pure C API
defined in the c subdirectory), or you can use it as the basis for an
extension module for your favorite programming language instead of writing
your own parser from scratch.
Example
The provided dump_json_ast is a simple program that reads GraphQL
text on stdin and prints a JSON representation of the AST to stdout.
The python subdirectory contains an example Python binding for the
pure C API.
Requirements
libgraphqlparser requires a C++ compiler that supports C++11. It also requires Mac OS X or Linux.
To run tests, first, compile and install the library as described above. Then,
please download googletest from
https://github.com/google/googletest/archive/release-1.8.0.zip
and unzip it in the test subdirectory. In consequence, a folder
googletest-release-1.8.0 should be contained in test. Next, within the
test folder, run cmake . and make to generate the runTests binary.
To execute the tests run ./test/runTests from the main folder.
Building libgraphqlparser
libgraphqlparser is built with CMake. If a
sufficiently-recent version of Flex and Bison are installed on your
system, it will use them; otherwise, it will rely on the checked-in
parser.tab.{c,h}pp and lexer.{h,cpp}.
To build libgraphqlparser from source:
$ # inside the project root:
$ cmake .
$ make
Then, to install it on your system:
$ make install
How libgraphqlparser works
libgraphqlparser uses flex and bison to generate a C++ parser for GraphQL. These tools work well but have idiosyncratic interfaces by modern standards, so GraphQLParser.h provides a simple interface to parse GraphQL.
In order to make it simpler to write code based around the GraphQL
AST, libgraphqlparser includes an extremely simple code generation
framework in the ast/ subdirectory. This framework is used to build
the AST classes themselves, as well as a visitor over the AST. It may
be easier to understand the output of the generation steps directly
(i.e., Ast.h, Ast.cpp, and AstVisitor.h) rather than trying to read
the generation scripts. Simply building libgraphqlparser will cause
these files to be generated.
libgraphqlparser also uses the AST generation framework to build a
pure C API in the c subdirectory. This API can be used from C code,
and it should also simplify the task of creating bindings to other
programming languages.
License
libgraphqlparser is MIT-licensed.