epp (stdlib v3.15.2)
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 -*-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
Link to this section Summary
Types
Handle to the epp server.
Functions
Closes the preprocessing of a file.
Returns the default encoding of Erlang source files.
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.
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).
Opens a file for preprocessing.
Equivalent to epp:open([{name, FileName}, {includes, IncludePath}]).
Equivalent to epp:open([{name, FileName}, {includes, IncludePath}, {macros, PredefMacros}]).
Returns the next Erlang form from the opened Erlang source file. Tuple {eof, Location} 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.
Preprocesses and parses an Erlang source file. Notice that tuple {eof, Location} returned at the end of the file is included as a "form".
Equivalent to epp:parse_file(FileName, [{includes, IncludePath}, {macros, PredefMacros}]).
Read the encoding from a file. Returns the read encoding, or none if no valid encoding is found.
Read the encoding from a binary. Returns the read encoding, or none if no valid encoding is found.
Returns the raw tokens of the next Erlang form from the opened Erlang source file. A 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.
Preprocesses an Erlang source file returning a list of the lists of raw tokens of each form. Notice that the tuple {eof, Line} returned at the end of the file is included as a "form", and any failures to scan a form are included in the list as tuples {error, ErrorInfo}.
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.
Link to this section Types
-type epp_handle() :: term().
Specs
epp_handle() :: pid().
Handle to the epp server.
-type macros() :: term().
Specs
macros() :: [atom() | {atom(), term()} | {atom(), term(), redefine}].
-type source_encoding() :: term().
Specs
source_encoding() :: latin1 | utf8.
-type warning_info() :: term().
Specs
warning_info() :: {erl_anno:location(), module(), term()}.
Link to this section Functions
close/1
Specs
close(Epp) -> ok when Epp :: epp_handle().
Closes the preprocessing of a file.
Specs
default_encoding() -> source_encoding().
Returns the default encoding of Erlang source files.
Specs
encoding_to_string(Encoding) -> string() when 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.
Specs
format_error(ErrorDescriptor) -> io_lib:chars() when 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).
Specs
open(Options) -> {ok, Epp} | {ok, Epp, Extra} | {error, ErrorDescriptor}
when
Options ::
[{default_encoding, DefEncoding :: source_encoding()} |
{includes, IncludePath :: [DirectoryName :: file:name()]} |
{source_name, SourceName :: file:name()} |
{macros, PredefMacros :: macros()} |
{name, FileName :: file:name()} |
{location, StartLocation :: erl_anno:location()} |
{fd, FileDescriptor :: file:io_device()} |
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}.
The option location is forwarded to the Erlang token scanner, see erl_scan:tokens/3,4.
open/2
Specs
open(FileName, IncludePath) -> {ok, Epp} | {error, ErrorDescriptor}
when
FileName :: file:name(),
IncludePath :: [DirectoryName :: file:name()],
Epp :: epp_handle(),
ErrorDescriptor :: term().
Equivalent to epp:open([{name, FileName}, {includes, IncludePath}]).
open/3
Specs
open(FileName, IncludePath, PredefMacros) -> {ok, Epp} | {error, ErrorDescriptor}
when
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/1
Specs
parse_erl_form(Epp) ->
{ok, AbsForm} | {error, ErrorInfo} | {warning, WarningInfo} | {eof, Location}
when
Epp :: epp_handle(),
AbsForm :: erl_parse:abstract_form(),
Location :: erl_anno:location(),
ErrorInfo :: erl_scan:error_info() | erl_parse:error_info(),
WarningInfo :: warning_info().
Returns the next Erlang form from the opened Erlang source file. Tuple {eof, Location} 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.
Specs
parse_file(FileName, Options) -> {ok, [Form]} | {ok, [Form], Extra} | {error, OpenError}
when
FileName :: file:name(),
Options ::
[{includes, IncludePath :: [DirectoryName :: file:name()]} |
{source_name, SourceName :: file:name()} |
{macros, PredefMacros :: macros()} |
{default_encoding, DefEncoding :: source_encoding()} |
{location, StartLocation :: erl_anno:location()} |
extra],
Form :: erl_parse:abstract_form() | {error, ErrorInfo} | {eof, Location},
Location :: erl_anno:location(),
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, Location} 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]}.
The option location is forwarded to the Erlang token scanner, see erl_scan:tokens/3,4.
parse_file/3
Specs
parse_file(FileName, IncludePath, PredefMacros) -> {ok, [Form]} | {error, OpenError}
when
FileName :: file:name(),
IncludePath :: [DirectoryName :: file:name()],
Form :: erl_parse:abstract_form() | {error, ErrorInfo} | {eof, Location},
PredefMacros :: macros(),
Location :: erl_anno:location(),
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}]).
Specs
read_encoding(FileName) -> source_encoding() | none when FileName :: file:name().
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.
Specs
read_encoding(FileName, Options) -> source_encoding() | none when FileName :: file:name(), Options :: [Option], Option :: {in_comment_only, boolean()}.
Specs
read_encoding_from_binary(Binary) -> source_encoding() | none when Binary :: binary().
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.
Specs
read_encoding_from_binary(Binary, Options) -> source_encoding() | none when Binary :: binary(), Options :: [Option], Option :: {in_comment_only, boolean()}.
Specs
scan_erl_form(Epp) -> {ok, Tokens} | {error, ErrorInfo} | {warning, WarningInfo} | {eof, Line}
when
Epp :: epp_handle(),
Tokens :: erl_scan:tokens(),
Line :: erl_anno:line(),
ErrorInfo :: erl_scan:error_info() | erl_parse:error_info(),
WarningInfo :: warning_info().
Returns the raw tokens of the next Erlang form from the opened Erlang source file. A 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.
Specs
scan_file(FileName, Options) -> {ok, [Form], Extra} | {error, OpenError}
when
FileName :: file:name(),
Options ::
[{includes, IncludePath :: [DirectoryName :: file:name()]} |
{source_name, SourceName :: file:name()} |
{macros, PredefMacros :: macros()} |
{default_encoding, DefEncoding :: source_encoding()}],
Form :: erl_scan:tokens() | {error, ErrorInfo} | {eof, Loc},
Loc :: erl_anno:location(),
ErrorInfo :: erl_scan:error_info(),
Extra :: [{encoding, source_encoding() | none}],
OpenError :: file:posix() | badarg | system_limit.
Preprocesses an Erlang source file returning a list of the lists of raw tokens of each form. Notice that the tuple {eof, Line} returned at the end of the file is included as a "form", and any failures to scan a form are included in the list as tuples {error, ErrorInfo}.
Specs
set_encoding(File) -> source_encoding() | none when 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.
Specs
set_encoding(File, Default) -> source_encoding() | none when 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.