Provided by: erlang-manpages_22.0.7+dfsg-1build1_all bug

NAME

       epp - An Erlang code preprocessor.

DESCRIPTION

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

       The Erlang source file encoding is selected by a comment in one of the first two lines  of
       the source file. The first string matching the regular expression coding\s*[:=]\s*([-a-zA-
       Z0-9])+ selects the encoding. If the matching string  is  not  a  valid  encoding,  it  is
       ignored.  The  valid encodings are Latin-1 and UTF-8, where the case of the characters can
       be chosen freely.

       Examples:

       %% coding: utf-8

       %% For this file we have chosen encoding = Latin-1

       %% -*- coding: latin-1 -*-

DATA TYPES

       macros() = [atom() | {atom(), term()}]

       epp_handle() = pid()

              Handle to the epp server.

       source_encoding() = latin1 | utf8

EXPORTS

       close(Epp) -> ok

              Types:

                 Epp = epp_handle()

              Closes the preprocessing of a file.

       default_encoding() -> source_encoding()

              Returns the default encoding of Erlang source files.

       encoding_to_string(Encoding) -> string()

              Types:

                 Encoding = source_encoding()

              Returns a string representation  of  an  encoding.  The  string  is  recognized  by
              read_encoding/1,2,  read_encoding_from_binary/1,2,  and set_encoding/1,2 as a valid
              encoding.

       format_error(ErrorDescriptor) -> io_lib:chars()

              Types:

                 ErrorDescriptor = term()

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

       open(Options) ->
               {ok, Epp} | {ok, Epp, Extra} | {error, ErrorDescriptor}

              Types:

                 Options =
                     [{default_encoding, DefEncoding :: source_encoding()} |
                      {includes, IncludePath :: [DirectoryName :: file:name()]} |
                      {source_name, SourceName :: file:name()} |
                      {macros, PredefMacros :: macros()} |
                      {name, FileName :: file:name()} |
                      extra]
                 Epp = epp_handle()
                 Extra = [{encoding, source_encoding() | none}]
                 ErrorDescriptor = term()

              Opens a file for preprocessing.

              If you want to change the file name of the  implicit  -file()  attributes  inserted
              during  preprocessing,  you can do with {source_name, SourceName}. If unset it will
              default to the name of the opened file.

              If extra is specified in Options, the return value is {ok, Epp, Extra}  instead  of
              {ok, Epp}.

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

              Types:

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

              Equivalent to epp:open([{name, FileName}, {includes, IncludePath}]).

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

              Types:

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

              Equivalent   to   epp:open([{name,  FileName},  {includes,  IncludePath},  {macros,
              PredefMacros}]).

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

              Types:

                 Epp = epp_handle()
                 AbsForm = erl_parse:abstract_form()
                 Line = erl_anno:line()
                 ErrorInfo = erl_scan:error_info() | erl_parse:error_info()
                 WarningInfo = warning_info()
                 warning_info() = {erl_anno:location(), module(), term()}

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

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

              Types:

                 FileName = file:name()
                 Options =
                     [{includes, IncludePath :: [DirectoryName :: file:name()]} |
                      {source_name, SourceName :: file:name()} |
                      {macros, PredefMacros :: macros()} |
                      {default_encoding, DefEncoding :: source_encoding()} |
                      extra]
                 Form =
                     erl_parse:abstract_form() | {error, ErrorInfo} | {eof, Line}
                 Line = erl_anno:line()
                 ErrorInfo = erl_scan:error_info() | erl_parse:error_info()
                 Extra = [{encoding, source_encoding() | none}]
                 OpenError = file:posix() | badarg | system_limit

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

              If  you  want  to  change the file name of the implicit -file() attributes inserted
              during preprocessing, you can do with {source_name, SourceName}. If unset  it  will
              default to the name of the opened file.

              If  extra  is specified in Options, the return value is {ok, [Form], Extra} instead
              of {ok, [Form]}.

       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_anno:line()
                 ErrorInfo = erl_scan:error_info() | erl_parse:error_info()
                 OpenError = file:posix() | badarg | system_limit

              Equivalent   to   epp:parse_file(FileName,   [{includes,   IncludePath},   {macros,
              PredefMacros}]).

       read_encoding(FileName) -> source_encoding() | none

       read_encoding(FileName, Options) -> source_encoding() | none

              Types:

                 FileName = file:name()
                 Options = [Option]
                 Option = {in_comment_only, boolean()}

              Read  the  encoding  from  a  file.  Returns the read encoding, or none if no valid
              encoding is found.

              Option in_comment_only is true by default,  which  is  correct  for  Erlang  source
              files. If set to false, the encoding string does not necessarily have to occur in a
              comment.

       read_encoding_from_binary(Binary) -> source_encoding() | none

       read_encoding_from_binary(Binary, Options) ->
                                    source_encoding() | none

              Types:

                 Binary = binary()
                 Options = [Option]
                 Option = {in_comment_only, boolean()}

              Read the encoding from a binary. Returns the read encoding, or  none  if  no  valid
              encoding is found.

              Option  in_comment_only  is  true  by  default,  which is correct for Erlang source
              files. If set to false, the encoding string does not necessarily have to occur in a
              comment.

       set_encoding(File) -> source_encoding() | none

              Types:

                 File = io:device()

              Reads  the  encoding  from  an  I/O  device  and  sets  the  encoding of the device
              accordingly. The position of the I/O device referenced by File is not affected.  If
              no  valid  encoding can be read from the I/O device, the encoding of the I/O device
              is set to the default encoding.

              Returns the read encoding, or none if no valid encoding is found.

       set_encoding(File, Default) -> source_encoding() | none

              Types:

                 Default = source_encoding()
                 File = io:device()

              Reads the encoding from  an  I/O  device  and  sets  the  encoding  of  the  device
              accordingly.  The position of the I/O device referenced by File is not affected. If
              no valid encoding can be read from the I/O device, the encoding of the  I/O  device
              is set to the encoding specified by Default.

              Returns the read encoding, or none if no valid encoding is found.

ERROR INFORMATION

       ErrorInfo  is  the standard ErrorInfo structure that is returned from all I/O modules. The
       format is as follows:

       {ErrorLine, Module, ErrorDescriptor}

       A string describing the error is obtained with the following call:

       Module:format_error(ErrorDescriptor)

SEE ALSO

       erl_parse(3erl)