epp.erl

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	    leave_file(From, St)		%This serious, just exit!
    end.

scan_toks([{'-',_Lh},{atom,Ld,define}|Toks], From, St) ->
    scan_define(Toks, Ld, From, St);
scan_toks([{'-',_Lh},{atom,Ld,undef}|Toks], From, St) ->
    scan_undef(Toks, Ld, From, St);
scan_toks([{'-',_Lh},{atom,Li,include}|Toks], From, St) ->
    scan_include(Toks, abs(Li), From, St);
scan_toks([{'-',_Lh},{atom,Li,include_lib}|Toks], From, St) ->
    scan_include_lib(Toks, abs(Li), From, St);
scan_toks([{'-',_Lh},{atom,Li,ifdef}|Toks], From, St) ->
    scan_ifdef(Toks, Li, From, St);
scan_toks([{'-',_Lh},{atom,Li,ifndef}|Toks], From, St) ->
    scan_ifndef(Toks, Li, From, St);
scan_toks([{'-',_Lh},{atom,Le,else}|Toks], From, St) ->
    scan_else(Toks, Le, From, St);
scan_toks([{'-',_Lh},{atom,Le,'if'}|Toks], From, St) ->
    scan_if(Toks, Le, From, St);
scan_toks([{'-',_Lh},{atom,Le,elif}|Toks], From, St) ->
    scan_elif(Toks, Le, From, St);
scan_toks([{'-',_Lh},{atom,Le,endif}|Toks], From, St) ->
    scan_endif(Toks, Le, From, St);
scan_toks([{'-',_Lh},{atom,Lf,file}|Toks0], From, St) ->
    case catch expand_macros(Toks0, {St#epp.macs, St#epp.uses}) of
	Toks1 when is_list(Toks1) ->
            scan_file(Toks1, Lf, From, St);
	{error,ErrL,What} ->
	    epp_reply(From, {error,{ErrL,epp,What}}),
	    wait_req_scan(St)
    end;
scan_toks(Toks0, From, St) ->
    case catch expand_macros(Toks0, {St#epp.macs, St#epp.uses}) of
	Toks1 when is_list(Toks1) ->
	    epp_reply(From, {ok,Toks1}),
	    wait_req_scan(St#epp{macs=scan_module(Toks1, St#epp.macs)});
	{error,ErrL,What} ->
	    epp_reply(From, {error,{ErrL,epp,What}}),
	    wait_req_scan(St)
    end.

scan_module([{'-',_Lh},{atom,_Lm,module},{'(',_Ll}|Ts], Ms) ->
    scan_module_1(Ts, [], Ms);
scan_module(_Ts, Ms) -> Ms.

scan_module_1([{atom,_,_}=A,{',',L}|Ts], As, Ms) ->
    %% Parameterized modules.
    scan_module_1([A,{')',L}|Ts], As, Ms);
scan_module_1([{atom,Ln,A},{')',_Lr}|_Ts], As, Ms0) ->
    Mod = lists:concat(lists:reverse([A|As])),
    Ms = dict:store({atom,'MODULE'},
		     {none,[{atom,Ln,list_to_atom(Mod)}]}, Ms0),
    dict:store({atom,'MODULE_STRING'}, {none,[{string,Ln,Mod}]}, Ms);
scan_module_1([{atom,_Ln,A},{'.',_Lr}|Ts], As, Ms) ->
    scan_module_1(Ts, [".",A|As], Ms);
scan_module_1([{'.',_Lr}|Ts], As, Ms) ->
    scan_module_1(Ts, As, Ms);
scan_module_1(_Ts, _As, Ms) -> Ms.

%% scan_define(Tokens, DefineLine, From, EppState)

scan_define([{'(',_Lp},{atom,Lm,M},{',',_Lc}|Toks], _Ld, From, St) ->
    case dict:find({atom,M}, St#epp.macs) of
	{ok,_Def} ->
	    epp_reply(From, {error,{Lm,epp,{redefine,M}}}),
	    wait_req_scan(St);
	error ->
	    scan_define_cont(From, St,
			     {atom, M},
			     {none,macro_expansion(Toks)})
    end;
scan_define([{'(',_Lp},{atom,Lm,M},{'(',_Lc}|Toks], Ld, From, St) ->
    case dict:find({atom,M}, St#epp.macs) of
	{ok,_Def} ->
	    epp_reply(From, {error,{Lm,epp,{redefine,M}}}),
	    wait_req_scan(St);
	error ->
	    case catch macro_pars(Toks, []) of
		{ok, {As, Me}} ->
		    scan_define_cont(From, St,
				    {atom, M},
				    {As, Me});
		_ ->
		    epp_reply(From, {error,{Ld,epp,{bad,define}}}),
		    wait_req_scan(St)
	    end
    end;
scan_define([{'(',_Lp},{var,Lm,M},{',',_Lc}|Toks], _Ld, From, St) ->
    case dict:find({atom,M}, St#epp.macs) of
	{ok,_Def} ->
	    epp_reply(From, {error,{Lm,epp,{redefine,M}}}),
	    wait_req_scan(St);
	error ->
	    scan_define_cont(From, St,
			     {atom, M},
			     {none,macro_expansion(Toks)})
    end;
scan_define([{'(',_Lp},{var,Lm,M},{'(',_Lc}|Toks], Ld, From, St) ->
    case dict:find({atom,M}, St#epp.macs) of
	{ok,_Def} ->
	    epp_reply(From, {error,{Lm,epp,{redefine,M}}}),
	    wait_req_scan(St);
	error ->
	    case catch macro_pars(Toks, []) of
		{ok, {As, Me}} ->
		    scan_define_cont(From, St,
				     {atom, M},
				     {As, Me});
		_ ->
		    epp_reply(From, {error,{Ld,epp,{bad,define}}}),
		    wait_req_scan(St)
	    end
    end;
scan_define(_Toks, Ld, From, St) ->
    epp_reply(From, {error,{Ld,epp,{bad,define}}}),
    wait_req_scan(St).

%%% Detection of circular macro expansions (which would either keep
%%% the compiler looping forever, or run out of memory):
%%% When a macro is defined, we store the names of other macros it
%%% uses in St#epp.uses. If any macro is undef'ed, that information
%%% becomes invalid, so we redo it for all remaining macros.
%%% The circularity detection itself is done when a macro is expanded:
%%% the information from St#epp.uses is traversed, and if a circularity
%%% is detected, an error message is thrown.

scan_define_cont(F, St, M, Def) ->
    Ms = dict:store(M, Def, St#epp.macs),
    U = dict:store(M, macro_uses(Def), St#epp.uses),
    scan_toks(F, St#epp{uses=U, macs=Ms}).

macro_uses(undefined) ->
    undefined;
macro_uses({_Args, Tokens}) ->
    Uses0 = macro_ref(Tokens),
    lists:usort(Uses0).

macro_ref([]) ->
    [];
macro_ref([{'?', _}, {'?', _} | Rest]) ->
    macro_ref(Rest);
macro_ref([{'?', _}, {atom, _, A} | Rest]) ->
    [{atom, A} | macro_ref(Rest)];
macro_ref([{'?', _}, {var, _, A} | Rest]) ->
    [{atom, A} | macro_ref(Rest)];
macro_ref([_Token | Rest]) ->
    macro_ref(Rest).

all_macro_uses(D0) ->
    L = dict:to_list(D0),
    D = dict:new(),
    add_macro_uses(L, D).

add_macro_uses([], D) ->
    D;
add_macro_uses([{Key, Def} | Rest], D0) ->
    add_macro_uses(Rest, dict:store(Key, macro_uses(Def), D0)).

%% scan_undef(Tokens, UndefLine, From, EppState)

scan_undef([{'(',_Llp},{atom,_Lm,M},{')',_Lrp},{dot,_Ld}], _Lu, From, St) ->
    scan_toks(From, St#epp{macs=dict:erase({atom,M}, St#epp.macs),
			   uses=all_macro_uses(St#epp.macs)});
scan_undef([{'(',_Llp},{var,_Lm,M},{')',_Lrp},{dot,_Ld}], _Lu, From,St) ->
    scan_toks(From, St#epp{macs=dict:erase({atom,M}, St#epp.macs),
			   uses=all_macro_uses(St#epp.macs)});
scan_undef(_Toks, Lu, From,St) ->
    epp_reply(From, {error,{Lu,epp,{bad,undef}}}),
    wait_req_scan(St).

%% scan_include(Tokens, IncludeLine, From, St)

scan_include([{'(',_Llp},{string,_Lf,NewName0},{')',_Lrp},{dot,_Ld}], Li, 
	     From, St) ->
    NewName = expand_var(NewName0),
    enter_file(St#epp.path, NewName, Li, From, St);
scan_include(_Toks, Li, From, St) ->
    epp_reply(From, {error,{Li,epp,{bad,include}}}),
    wait_req_scan(St).

%% scan_include_lib(Tokens, IncludeLine, From, EppState)
%%  For include_lib we first test if we can find the file through the
%%  normal search path, if not we assume that the first directory name
%%  is a library name, find its true directory and try with that.

find_lib_dir(NewName) ->
    [Lib | Rest] = filename:split(NewName),
    {code:lib_dir(Lib), Rest}.

scan_include_lib([{'(',_Llp},{string,_Lf,_NewName0},{')',_Lrp},{dot,_Ld}], Li,
		 From, St)
  when length(St#epp.sstk) >= 8 ->
    epp_reply(From, {error,{Li,epp,{depth,"include_lib"}}}),
    wait_req_scan(St);
scan_include_lib([{'(',_Llp},{string,_Lf,NewName0},{')',_Lrp},{dot,_Ld}], Li,
		 From, St) ->
    NewName = expand_var(NewName0),
    case file:path_open(St#epp.path, NewName, read) of
	{ok,NewF,Pname} ->
	    wait_req_scan(enter_file2(NewF, Pname, From, St, 1));
	{error,_E1} ->
	    case catch find_lib_dir(NewName) of
		{LibDir, Rest} when is_list(LibDir) ->
		    LibName = filename:join([LibDir | Rest]),
		    case file:open(LibName, [read]) of
			{ok,NewF} ->
			    ExtraPath = [filename:dirname(LibName)],
			    wait_req_scan(enter_file2(NewF, LibName, From, 
                                                      St, 1, ExtraPath));
			{error,_E2} ->
			    epp_reply(From,
				      {error,{Li,epp,{include,lib,NewName}}}),
			    wait_req_scan(St)
		    end;
		_Error ->
		    epp_reply(From, {error,{Li,epp,{include,lib,NewName}}}),
		    wait_req_scan(St)
	    end
    end;
scan_include_lib(_Toks, Li, From, St) ->
    epp_reply(From, {error,{Li,epp,{bad,include_lib}}}),
    wait_req_scan(St).

%% scan_ifdef(Tokens, IfdefLine, From, EppState)
%% scan_ifndef(Tokens, IfdefLine, From, EppSate)
%%  Handle the conditional parsing of a file.
%%  Report a badly formed if[n]def test and then treat as undefined macro.

scan_ifdef([{'(',_Llp},{atom,_Lm,M},{')',_Lrp},{dot,_Ld}], _Li, From, St) ->
    case dict:find({atom,M}, St#epp.macs) of
	{ok,_Def} ->
	    scan_toks(From, St#epp{istk=[ifdef|St#epp.istk]});
	error ->
	    skip_toks(From, St, [ifdef])
    end;
scan_ifdef([{'(',_Llp},{var,_Lm,M},{')',_Lrp},{dot,_Ld}], _Li, From, St) ->
    case dict:find({atom,M}, St#epp.macs) of
	{ok,_Def} ->
	    scan_toks(From, St#epp{istk=[ifdef|St#epp.istk]});
	error ->
	    skip_toks(From, St, [ifdef])
    end;
scan_ifdef(_Toks, Li, From, St) ->
    epp_reply(From, {error,{Li,epp,{bad,ifdef}}}),
    wait_req_skip(St, [ifdef]).

scan_ifndef([{'(',_Llp},{atom,_Lm,M},{')',_Lrp},{dot,_Ld}], _Li, From, St) ->
    case dict:find({atom,M}, St#epp.macs) of
	{ok,_Def} ->
	    skip_toks(From, St, [ifndef]);
	error ->
	    scan_toks(From, St#epp{istk=[ifndef|St#epp.istk]})
    end;
scan_ifndef([{'(',_Llp},{var,_Lm,M},{')',_Lrp},{dot,_Ld}], _Li, From, St) ->
    case dict:find({atom,M}, St#epp.macs) of
	{ok,_Def} ->
	    skip_toks(From, St, [ifndef]);
	error ->
	    scan_toks(From, St#epp{istk=[ifndef|St#epp.istk]})
    end;
scan_ifndef(_Toks, Li, From, St) ->
    epp_reply(From, {error,{Li,epp,{bad,ifndef}}}),
    wait_req_scan(St).

%% scan_else(Tokens, ElseLine, From, EppState)
%%  If we are in an if body then convert to else and skip, if we are in an
%%  else or not in anything report an error.

scan_else([{dot,_Ld}], Le, From, St) ->
    case St#epp.istk of
	[else|Cis] ->
	    epp_reply(From, {error,{Le,epp,{illegal,"repeated",else}}}),
	    wait_req_skip(St#epp{istk=Cis}, [else]);
	[_I|Cis] ->
	    skip_toks(From, St#epp{istk=Cis}, [else]);
	[] ->
	    epp_reply(From, {error,{Le,epp,{illegal,"unbalanced",else}}}),
	    wait_req_scan(St)
    end;
scan_else(_Toks, Le, From, St) ->
    epp_reply(From, {error,{Le,epp,{bad,else}}}),
    wait_req_scan(St).

%% scan_if(Tokens, EndifLine, From, EppState)
%%  Handle the conditional parsing of a file.
%%  Report a badly formed if test and then treat as false macro.

scan_if(_Toks, Le, From, St) ->
    epp_reply(From, {error,{Le,epp,{'NYI','if'}}}),
    wait_req_skip(St, ['if']).

%% scan_elif(Tokens, EndifLine, From, EppState)
%%  Handle the conditional parsing of a file.
%%  Report a badly formed if test and then treat as false macro.

scan_elif(_Toks, Le, From, St) ->
    epp_reply(From, {error,{Le,epp,{'NYI','elif'}}}),
    wait_req_skip(St, ['elif']).

%% scan_endif(Tokens, EndifLine, From, EppState)
%%  If we are in an if body then exit it, else report an error.

scan_endif([{dot,_Ld}], Le, From, St) ->
    case St#epp.istk of
	[_I|Cis] ->
	    scan_toks(From, St#epp{istk=Cis});
	[] ->
	    epp_reply(From, {error,{Le,epp,{illegal,"unbalanced",endif}}}),
	    wait_req_scan(St)
    end;
scan_endif(_Toks, Le, From, St) ->
    epp_reply(From, {error,{Le,epp,{bad,endif}}}),
    wait_req_scan(St).

%% scan_file(Tokens, FileLine, From, EppState)
%%  Set the current file and line to the given file and line.
%%  Note that the line of the attribute itself is kept.

scan_file([{'(',_Llp},{string,_Ls,Name},{',',_Lc},{integer,_Li,Ln},{')',_Lrp},
           {dot,_Ld}], Lf, From, St) ->
    enter_file_reply(From, Name, Ln, -abs(Lf)),
    Ms = dict:store({atom,'FILE'}, {none,[{string,1,Name}]}, St#epp.macs),
    scan_toks(From, St#epp{name=Name,line=Ln+(St#epp.line-Lf),macs=Ms});
scan_file(_Toks, Lf, From, St) ->
    epp_reply(From, {error,{Lf,epp,{bad,file}}}),
    wait_req_scan(St).

%% skip_toks(From, EppState, SkipIstack)
%%  Skip over forms until current conditional has been exited. Handle
%%  nested conditionals and repeated 'else's.