A mapper record implements one "method" per syntactic category, using an open recursion style: each method takes as its first argument the mapper to be applied to children in the syntax tree.

A default mapper, which implements a "deep identity" mapping.

Can be used within a ppx preprocessor to know which tool is calling it "ocamlc", "ocamlopt", "ocamldoc", "ocamldep", "ocaml", ... Some global variables that reflect command-line options are automatically synchronized between the calling tool and the ppx preprocessor: Clflags.include_dirs, Load_path, Clflags.open_modules, Clflags.for_package, Clflags.debug.

Apply a mapper (parametrized by the unit name) to a dumped parsetree found in the source file and put the result in the target file. The structure or signature field of the mapper is applied to the implementation or interface.

Entry point to call to implement a standalone -ppx rewriter from a mapper, parametrized by the command line arguments. The current unit name can be obtained from Location.input_name. This function implements proper error reporting for uncaught exceptions.

Apply the register_function. The default behavior is to run the mapper immediately, taking arguments from the process command line. This is to support a scenario where a mapper is linked as a stand-alone executable. It is possible to overwrite the register_function to define "-ppx drivers", which combine several mappers in a single process. Typically, a driver starts by defining register_function to a custom implementation, then lets ppx rewriters (linked statically or dynamically) register themselves, and then run all or some of them. It is also possible to have -ppx drivers apply rewriters to only specific parts of an AST. The first argument to register is a symbolic name to be used by the ppx driver.

Encode an error into an 'ocaml.error' extension node which can be inserted in a generated Parsetree. The compiler will be responsible for reporting the error.

Encode a warning message into an 'ocaml.ppwarning' attribute which can be inserted in a generated Parsetree. The compiler will be responsible for reporting the warning.

Extract information from the current environment and encode it into an attribute which is prepended to the list of structure items in order to pass the information to an external processor.

Same as add_ppx_context_str, but for signatures.

Drop the ocaml.ppx.context attribute from a structure. If restore is true, also restore the associated data in the current process.

Same as drop_ppx_context_str, but for signatures.