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| uwiger |
 Posted: Thu Jul 06, 2006 2:32 pm |
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User
Joined: 03 Jul 2006
Posts: 604
Location: Sweden
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So, I was able to hack my way in, in lieu of a documented solution:
1) Copy file_io_server.erl (from kernel) to ram_file_io_server.erl
and modify slightly:
diff ram_file_io_server.erl file_io_server.erl
18c18
< -module(ram_file_io_server).
---
> -module(file_io_server).
27c27
< -define(PRIM_FILE, ram_file).
---
> -define(PRIM_FILE, prim_file).
2) Write the following code:
compile_string(_W, Mod, Str) ->
Fname = Mod ++ ".erl",
{ok, Fd} = open_ram_file(Fname),
file:write(Fd, Str),
file:position(Fd, 0),
case epp_dodger:parse(Fd) of
{ok, Tree} ->
Forms = revert_tree(Tree),
close_ram_file(Fd),
Forms;
Error ->
close_ram_file(Fd),
Error
end.
open_ram_file(Fname) ->
ram_file_io_server:start(self(), Fname, [read,write]).
close_ram_file(Fd) ->
file:close(Fd).
revert_tree(Tree) ->
[erl_syntax:revert(T) || T <- Tree].
The 'ram' option to file:open/2 is not documented; the whole ram_file
framework seems to be secret. The problem with file:open(F, [ram, read,
write]) is that the opened file seems to get the same type of semantics
as with 'raw'. Epp_dodger uses the io module to parse the contents
behind Fd, and this doesn't work with raw devices.
(One could of course imagine a slight rewrite of file_io_server so that
it accepts some other low-level file driver other than prim_file... but
file_io_server is by all means undocumented too.)
After this, one just needs to call
{ok,M,Bin} = compile:forms(Forms, [binary]),
compile:load_binary(M, F, Bin).
BR,
Ulf W
> -----Original Message-----
> From: Ulf Wiger (AL/EAB)
> Sent: den 6 juli 2006 14:22
> To: erlang-questions@erlang.org
> Subject: compiling a module from a string
>
>
> I want to effectively call
>
> Str = "-module(m).\n-export([foo/0]).\nfoo() -> foo.\n".
> compile:string(Str, [binary]).
>
>
> Of course, this doesn't work, since compile.erl assumes that
> the source has to come from a file. So does epp.erl, BTW, and
> epp_dodger.
>
> A naive, but futile approach is of course:
>
> {ok, Tokens, _} = erl_scan:string(Str),
> erl_parse:tokens(Tokens).
>
> I'm sure there's a elegant sequence of commands that does
> this, but which is it?
>
> BR,
> Ulf W
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| axel |
| Posted: Thu Jul 06, 2006 2:59 pm |
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Joined: 03 Mar 2005
Posts: 271
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On 2006-07-06 16:19, Ulf Wiger (AL/EAB) wrote:
>> Of course, this doesn't work, since compile.erl assumes that
>> the source has to come from a file. So does epp.erl, BTW, and
>> epp_dodger.
when faced with a similar problem for a pretty printer (epp_dodger
wanting a file) i found that epp_dodger:parse/1 could handle an io
object, instead of a file. so i wrote a string_io module that has
open()/close() and received the io_requests. would this have worked for
you? ie, can compile take an io object?
bengt
--
EPO guidelines 1978: "If the contribution to the known art resides
solely in a computer program then the subject matter is not
patentable in whatever manner it may be presented in the claims."
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| uwiger |
| Posted: Thu Jul 06, 2006 8:40 pm |
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Joined: 03 Jul 2006
Posts: 604
Location: Sweden
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I want to effectively call
Str = "-module(m).\n-export([foo/0]).\nfoo() -> foo.\n".
compile:string(Str, [binary]).
Of course, this doesn't work, since compile.erl assumes that the source
has to come from a file. So does epp.erl, BTW, and epp_dodger.
A naive, but futile approach is of course:
{ok, Tokens, _} = erl_scan:string(Str),
erl_parse:tokens(Tokens).
I'm sure there's a elegant sequence of commands that does this, but
which is it?
BR,
Ulf W
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| mats |
| Posted: Mon Jul 10, 2006 11:03 am |
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Joined: 28 Feb 2005
Posts: 168
Location: budapest,hungary
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Ulf Wiger (AL/EAB) wrote:
> I want to effectively call
>
> Str = "-module(m).\n-export([foo/0]).\nfoo() -> foo.\n".
> compile:string(Str, [binary]).
this should work iff there are no #@#$&* macros. if there is, it's pretty
easy to write a subset of epp and call it between scanning and parsing.
mats
cl(Text) ->
Forms = scan_and_parse(Text,1,[]),
{ok,Mod,Bin} = compile:forms(Forms),
code:load_binary(Mod,"generated",Bin).
scan_and_parse([],_Line,Forms) -> lists:reverse(Forms);
scan_and_parse(Text,Line,Forms) ->
{done,{ok,Toks,NLine},Cont} = erl_scan:tokens([],Text,Line),
{ok,Form} = erl_parse:parse_form(Toks),
scan_and_parse(Cont,NLine,[Form|Forms]).
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| uwiger |
| Posted: Mon Jul 10, 2006 11:32 am |
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User
Joined: 03 Jul 2006
Posts: 604
Location: Sweden
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MaCro = Mats Cronqvist wrote:
> >
> > Str = "-module(m).\n-export([foo/0]).\nfoo() -> foo.\n".
> > compile:string(Str, [binary]).
>
> this should work iff there are no #@#$&* macros. if there
> is, it's pretty easy to write a subset of epp and call it
> between scanning and parsing.
Well, my ram_file_io_server works like a charm and lets me
use all the wonderful macros too. (:
/U
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| mats |
| Posted: Mon Jul 10, 2006 11:44 am |
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Joined: 28 Feb 2005
Posts: 168
Location: budapest,hungary
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Ulf Wiger (AL/EAB) wrote:
>
> MaCro = Mats Cronqvist wrote:
>>> Str = "-module(m).\n-export([foo/0]).\nfoo() -> foo.\n".
>>> compile:string(Str, [binary]).
>> this should work iff there are no #@#$&* macros. if there
>> is, it's pretty easy to write a subset of epp and call it
>> between scanning and parsing.
>
> Well, my ram_file_io_server works like a charm and lets me
> use all the wonderful macros too. (:
>
my post was mainly to inform the lurkers that it is not necessary to hack
around in the kernel sources.
of course, if i can save even one poor, unsuspecting soul from using macros i
will surely get my reward in the hereafter.
mats
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