epp

19962012 Ericsson AB. All Rights Reserved. The contents of this file are subject to the Erlang Public License, Version 1.1, (the "License"); you may not use this file except in compliance with the License. You should have received a copy of the Erlang Public License along with this software. If not, it can be retrieved online at http://www.erlang.org/. Software distributed under the License is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for the specific language governing rights and limitations under the License. epp Kenneth Lundin Kenneth Lundin 1 Kenneth Lundin 97-01-31 B epp.sgml

epp An Erlang Code Preprocessor

The Erlang code preprocessor includes functions which are used by compile to preprocess macros and include files before the actual 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 that matches 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 -*-

Handle to the epp server.

Open a file for preprocessing

Opens a file for preprocessing.

Close the preprocessing of the file associated with Epp

Closes the preprocessing of a file.

Return the next Erlang form from the opened Erlang source file

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.

Preprocess and parse an Erlang source file

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

Return the default encoding of Erlang source files

Returns the default encoding of Erlang source files.

Return a string representation of an encoding

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

Read the encoding from a file

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

The 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 and set the encoding of an IO device

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

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

Format an error descriptor

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)