Re: DSL in lua

[Vasiliy Tolstov <v.tolstov@...>]

Very interesting solution. Thanks!

2012/12/7 Philipp Janda <siffiejoe@gmx.net>:
> Am 06.12.2012 06:52, schrieb Vasiliy Tolstov:
>>
>> Hello.
>
>
> Hi!
>
>
>> What is the best way to create custom DSL in Lua? Google says, that it
>> can be possible via base lua or using lpeg.
>>
>> I need something like this
>> direcotry "/etc/" {
>>    owner "root"
>>    group "wheel"
>>    mode "0755"
>>    action "create"
>> }
>>
>> Can somebody provie minimal lua code for this sample? How can i do
>> this using lua lpeg?
>
>
> Here is a possible solution using LPeg:
> #!/usr/bin/lua
>
> local grammar = require( "grammar" )
>
> local g = grammar.define( function(_ENV)
>   local _ = WS^0
>   local str_E = (P'"'*C( (ANY-P'"')^0 )*P'"') +
>                 E"string literal expected"
>   local eof = -ANY + E"directory expected"
>
>   startrule( "dsl", _ * (V"directory")^0 * eof )
>   rule( "directory", W"directory" * _ * (str_E) * _ *
>                      (P"{"+E"{ expected") * _ *
>                      (V"owner" + V"group" + V"mode" + V"action")^0 *
>                      (P"}"+E"owner|group|mode|action|} expected") * _ )
>   rule( "owner", W"owner" * _ * (str_E) * _ )
>   rule( "group", W"group" * _ * (str_E) * _ )
>   rule( "mode", W"mode" * _ * (str_E) * _ )
>   rule( "action", W"action" * _ * (str_E) * _ )
> end )
>
>
> local function test( s )
>   local ok, ast = pcall( grammar.parsestring, g, s )
>   if ok then
>     grammar.dumpast( ast )
>   else
>     print( ast )
>   end
>   print( ("#"):rep( 80 ) )
> end
>
> test[[
> directory "/etc/" {
>
>   owner "root"
>   group "wheel"
>   mode "0755"
>   action "create"
> }
> ]]
>
> test[[
> directory "/etc/" {
>   owner "root"
>   gruop "wheel"
>   mode "0755"
>   action "create"
> }
> ]]
>
> But it requires my grammar-module[1] (which is still work-in-progress). If
> you want to use it anyway, consider it MIT-licensed.
>
>   [1]: http://lua.siffiejoe.dtdns.net/grammar/grammar.lua
>
> Output is:
> {
>   id = dsl,  pos = 1
>   1 = {
>     id = directory,  pos = 1
>     1 = /etc/
>     2 = {
>       id = owner,  pos = 23
>       1 = root
>     }
>     3 = {
>       id = group,  pos = 38
>       1 = wheel
>     }
>     4 = {
>       id = mode,  pos = 54
>       1 = 0755
>     }
>     5 = {
>       id = action,  pos = 68
>       1 = create
>     }
>   }
> }
> ################################################################################
> ["directory "/etc/" {\n..."]:3: parse error, owner|group|mode|action|}
> expected
>   gruop "wheel"
>   ^
> ################################################################################
>
>
> HTH,
> Philipp
>
>
>
>



-- 
Vasiliy Tolstov,
Clodo.ru
e-mail: v.tolstov@selfip.ru
jabber: vase@selfip.ru