epp(3)

NAME
epp - An Erlang Code Preprocessor

DESCRIPTION

The Erlang code preprocessor includes functions which are used by compile to preprocess macros and include files before the actual parsing takes place.

DATA TYPES
macros() = [{atom(), term()}]
epp_handle() = pid()

    Handle to the epp server.

EXPORTS

open(FileName, IncludePath) ->
        {ok, Epp} | {error, ErrorDescriptor}
open(FileName, IncludePath, PredefMacros) ->
        {ok, Epp} | {error, ErrorDescriptor}

    Types:
        FileName = file:name()
        IncludePath = [DirectoryName :: file:name()]
        PredefMacros = macros()
        Epp = epp_handle()
        ErrorDescriptor = term()

    Opens a file for preprocessing.

close(Epp) -> ok

    Types:
        Epp = epp_handle()

    Closes the preprocessing of a file.

parse_erl_form(Epp) ->
                  {ok, AbsForm} | {eof, Line} | {error, ErrorInfo}

    Types:
        Epp = epp_handle()
        AbsForm = erl_parse:abstract_form()
        Line = erl_scan:line()
        ErrorInfo = erl_scan:error_info() | erl_parse:error_info()

    Returns the next Erlang form from the opened Erlang source file. The tuple {eof, Line} is returned at end-of-file. The first form corresponds to an implicit attribute -file(File,1)., where File is the name of the file.

parse_file(FileName, IncludePath, PredefMacros) ->
              {ok, [Form]} | {error, OpenError}

    Types:
        FileName = file:name()
        IncludePath = [DirectoryName :: file:name()]
        Form = erl_parse:abstract_form()
             | {error, ErrorInfo}
             | {eof, Line}
        PredefMacros = macros()
        Line = erl_scan:line()
        ErrorInfo = erl_scan:error_info() | erl_parse:error_info()
        OpenError = file:posix() | badarg | system_limit

    Preprocesses and parses an Erlang source file. Note that the tuple {eof, Line} returned at end-of-file is included as a "form".

format_error(ErrorDescriptor) -> io_lib:chars()

    Types:
        ErrorDescriptor = term()

    Takes an ErrorDescriptor and returns a string which describes the error or warning. This function is usually called implicitly when processing an ErrorInfo structure (see below).

ERROR INFORMATION

The ErrorInfo mentioned above is the standard ErrorInfo structure which is returned from all IO modules. It has the following format:

    {ErrorLine, Module, ErrorDescriptor}

A string which describes the error is obtained with the following call:

    Module:format_error(ErrorDescriptor)

SEE ALSO

erl_parse(3)