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This makes the result of code generation independent of the order in which classes are defined in the schema, and makes additional topological sorting not required. Being independent from schema order will be important for reviewing the move to a pure python schema, as generated code will be left untouched.
Code generation suite
This directory contains the code generation suite used by the Swift extractor and the QL library. This suite will use
the abstract class specification of schema.yml to generate:
- the
dbschemefile (seedbschemegen.py) - the QL generated code and when
appropriate the corresponding stubs (see
qlgen.py) - C++ tags and trap entries (see
trapgen.py) - C++ structured classes (see
cppgen.py)
Usage
By default bazel run //swift/codegen will update all checked-in generated files (dbscheme and QL sources). You can
append -- followed by other options to tweak the behaviour, which is mainly intended for debugging.
See bazel run //swift/codegen -- --help for a list of all options. In particular --generate can be used with a comma
separated list to select what to generate (choosing among dbscheme, ql, trap and cpp).
C++ code is generated during build (see swift/extractor/trap/BUILD.bazel). After a
build you can browse the generated code in bazel-bin/swift/extractor/trap/generated.
Implementation notes
The suite uses mustache templating for generation. Templates are
in the templates directory, prefixed with the generation target they are used for.
Rather than passing dictionaries to the templating engine, python dataclasses are used as defined
in the lib directory. For each of the four generation targets the entry point for the implementation is
specified as the generate function in the modules within the generators directory.
Finally, codegen.py is the driver script gluing everything together and specifying the command line
options.
Unit tests are in the test directory and can be run via bazel test //swift/codegen/test.
For more details about each specific generation target, please refer to the module docstrings
in the generators directory.