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 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 -*-
Types
macros() = [{atom(), term()}]
epp_handle() = pid()
Handle to the epp server.
source_encoding() = latin1 | utf8
Functions
open(FileName, IncludePath) ->
{ok, Epp} | {error, ErrorDescriptor}
FileName = file:name()
IncludePath = [DirectoryName :: file:name()]
Epp = epp_handle()
ErrorDescriptor = term()
open(FileName, IncludePath, PredefMacros) ->
{ok, Epp} | {error, ErrorDescriptor}
FileName = file:name()
IncludePath = [DirectoryName :: file:name()]
PredefMacros = macros()
Epp = epp_handle()
ErrorDescriptor = term()
Opens a file for preprocessing.
parse_erl_form(Epp) ->
{ok, AbsForm} | {eof, Line} | {error, ErrorInfo}
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,
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}
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,
returned at end-of-file is
included as a "form".
default_encoding() -> source_encoding()
Returns the default encoding of Erlang source files.
encoding_to_string(Encoding) -> string()
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
as a valid encoding.
read_encoding(FileName) -> source_encoding() | none
FileName = file:name()
read_encoding(FileName, Options) -> source_encoding() | none
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 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_encoding_from_binary(Binary) -> source_encoding() | none
Binary = binary()
read_encoding_from_binary(Binary, Options) ->
source_encoding() | none
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 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.
set_encoding(File) -> source_encoding() | none
File = 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
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_error(ErrorDescriptor) -> io_lib:chars()
ErrorDescriptor = term()
Takes an
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)