epp.erl

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%% ``The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved via the world wide web at http://www.erlang.org/.
%% 
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%% 
%% The Initial Developer of the Original Code is Ericsson Utvecklings AB.
%% Portions created by Ericsson are Copyright 1999, Ericsson Utvecklings
%% AB. All Rights Reserved.''
%% 
%%     $Id $
%%
-module(epp).

%% An Erlang code preprocessor.

-export([open/2,open/3,close/1,format_error/1]).
-export([scan_erl_form/1,parse_erl_form/1,macro_defs/1]).
-export([parse_file/3,parse_file/4]).
-export([interpret_file_attribute/1]).

%% Epp state record.
-record(epp, {file,				%Current file
	      line=1,				%Current line number
	      name="",				%Current file name
	      istk=[],				%Ifdef stack
	      sstk=[],				%State stack
	      path=[],				%Include-path
	      macs=dict:new(),			%Macros
	      uses=dict:new()			%Macro use structure
	     }).

%%% Note on representation: as tokens, both {var, Line, Name} and
%%% {atom, Line, Name} can occur as macro identifiers. However, keeping
%%% this distinction here is done for historical reasons only: previously,
%%% ?FOO and ?'FOO' were not the same, but now they are. Removing the
%%% distinction in the internal representation would simplify the code
%%% a little.

%% open(FileName, IncludePath)
%% open(FileName, IncludePath, PreDefMacros)
%% close(Epp)
%% scan_erl_form(Epp)
%% parse_erl_form(Epp)
%% macro_defs(Epp)

open(File, Path) ->
    open(File, Path, []).

open(File, Path, Pdm) ->
    Self = self(),
    Epp = spawn(fun() -> server(Self, File, Path, Pdm) end),
    epp_request(Epp).

close(Epp) ->
    %% Make sure that close is synchronous as a courtesy to test
    %% cases that test for resource leaks.
    Ref = erlang:monitor(process, Epp),
    R = epp_request(Epp, close),
    receive {'DOWN',Ref,_,_,_} -> ok end,
    R.

scan_erl_form(Epp) ->
    epp_request(Epp, scan_erl_form).

parse_erl_form(Epp) ->
    case epp_request(Epp, scan_erl_form) of
	{ok,Toks} ->
	    erl_parse:parse_form(Toks);
	Other ->
	    Other
    end.

macro_defs(Epp) ->
    epp_request(Epp, macro_defs).

%% format_error(ErrorDescriptor) -> String
%%  Return a string describing the error.

format_error(cannot_parse) ->
    io_lib:format("cannot parse file, giving up", []);
format_error({bad,W}) ->
    io_lib:format("badly formed '~s'", [W]);
format_error({call,What}) ->
    io_lib:format("illegal macro call '~s'",[What]);
format_error({undefined,M}) ->
    io_lib:format("undefined macro '~w'", [M]);
format_error({depth,What}) ->
    io_lib:format("~s too deep",[What]);
format_error({mismatch,M}) ->
    io_lib:format("argument mismatch for macro '~w'", [M]);
format_error({arg_error,M}) ->
    io_lib:format("badly formed argument for macro '~w'", [M]);
format_error({redefine,M}) ->
    io_lib:format("redefining macro '~w'", [M]);
format_error({circular,M}) ->
    io_lib:format("circular macro '~w'", [M]);
format_error({include,W,F}) ->
    io_lib:format("can't find include ~s \"~s\"", [W,F]);
format_error({illegal,How,What}) ->
    io_lib:format("~s '-~s'", [How,What]);
format_error({'NYI',What}) ->
    io_lib:format("not yet implemented '~s'", [What]);
format_error(E) -> file:format_error(E).

%% parse_file(FileName, IncludePath, [PreDefMacro]) ->
%%	{ok,[Form]} | {error,OpenError}

parse_file(Ifile, Path, Predefs) ->
    parse_file(Ifile, Path, Predefs, []).

parse_file(Ifile, Path, Predefs, Options) ->
    case open(Ifile, Path, Predefs) of
	{ok,Epp} ->
	    Forms = parse_file(Epp, Options),
	    close(Epp),
	    {ok,Forms};
	{error,E} ->
	    {error,E}
    end.

%% parse_file(Epp) ->
%%	[Form]

parse_file(Epp, Options) ->
    case parse_erl_form(Epp) of
	{ok,Form} ->
	    case Form of
		{attribute,La,record,{Record, Val}} ->
		    case lists:member(typed_record,Options) of
			false ->
			    [{attribute, La, record,
			      {Record, normalize_typed_record_fields(Val)}}
			     |parse_file(Epp, Options)];
			true ->
			    [Form|parse_file(Epp, Options)]
		    end;
		_ ->
		    [Form|parse_file(Epp, Options)]
	    end;
	{error,E} ->
	    [{error,E}|parse_file(Epp, Options)];
	{eof,Line} ->
	    [{eof,Line}]
    end.

normalize_typed_record_fields([]) ->[];
normalize_typed_record_fields([{typed_record_field,Field,_}|Rest]) ->
    [Field|normalize_typed_record_fields(Rest)];
normalize_typed_record_fields([Field|Rest]) ->
    [Field|normalize_typed_record_fields(Rest)].

%% server(StarterPid, FileName, Path, PreDefMacros)

server(Pid, Name, Path, Pdm) ->
    process_flag(trap_exit, true),
    case file:open(Name, [read]) of
	{ok,File} ->
	    Ms0 = predef_macros(Name),
	    case user_predef(Pdm, Ms0) of
		{ok,Ms1} ->
		    epp_reply(Pid, {ok,self()}),
		    St = #epp{file=File,name=Name,path=Path,macs=Ms1},
		    From = wait_request(St),
		    enter_file_reply(From, Name, 1, 1),
		    wait_req_scan(St);
		{error,E} ->
		    epp_reply(Pid, {error,E})
	    end;
	{error,E} ->
	    epp_reply(Pid, {error,E})
    end.

%% predef_macros(FileName) -> Macrodict
%%  Initialise the macro dictionary with the default predefined macros,
%%  FILE, LINE, MODULE as undefined, MACHINE and MACHINE value.

predef_macros(File) ->
    Ms0 = dict:new(),
    Ms1 = dict:store({atom,'FILE'}, {none,[{string,1,File}]}, Ms0),
    Ms2 = dict:store({atom,'LINE'}, {none,[{integer,1,1}]}, Ms1),
    Ms3 = dict:store({atom,'MODULE'}, undefined, Ms2),
    Ms31 = dict:store({atom,'MODULE_STRING'}, undefined, Ms3),
    Machine = list_to_atom(erlang:system_info(machine)),
    Ms4 = dict:store({atom,'MACHINE'}, {none,[{atom,1,Machine}]}, Ms31),
    dict:store({atom,Machine}, {none,[{atom,1,true}]}, Ms4).

%% user_predef(PreDefMacros, Macros) ->
%%	{ok,MacroDict} | {error,E}
%%  Add the predefined macros to the macros dictionary. A macro without a
%%  value gets the value 'true'.

user_predef([{M,Val}|Pdm], Ms) when is_atom(M) ->
    case dict:find({atom,M}, Ms) of
	{ok,_Def} ->
	    {error,{redefine,M}};
	error ->
	    Exp = erl_parse:tokens(erl_parse:abstract(Val)),
	    user_predef(Pdm, dict:store({atom,M}, {none,Exp}, Ms))
    end;
user_predef([M|Pdm], Ms) when is_atom(M) ->
    case dict:find({atom,M}, Ms) of
	{ok,_Def} ->
	    {error,{redefine,M}};
	error ->
	    user_predef(Pdm, dict:store({atom,M}, {none,[{atom,1,true}]}, Ms))
    end;
user_predef([Md|_Pdm], _Ms) -> {error,{bad,Md}};
user_predef([], Ms) -> {ok,Ms}.

%% wait_request(EppState) -> RequestFrom
%% wait_req_scan(EppState)
%% wait_req_skip(EppState, SkipIstack)
%%  Handle requests, processing trivial requests directly. Either return
%%  requestor or scan/skip tokens.

wait_request(St) ->
    receive
	{epp_request,From,scan_erl_form} -> From;
	{epp_request,From,macro_defs} ->
	    epp_reply(From, dict:to_list(St#epp.macs)),
	    wait_request(St);
	{epp_request,From,close} ->
	    file:close(St#epp.file),
	    epp_reply(From, ok),
	    exit(normal);
	{'EXIT',_,R} ->
	    exit(R);
	Other ->
	    io:fwrite("Epp: unknown '~w'\n", [Other]),
	    wait_request(St)
    end.

wait_req_scan(St) ->
    From = wait_request(St),
    scan_toks(From, St).

wait_req_skip(St, Sis) ->
    From = wait_request(St),
    skip_toks(From, St, Sis).
	
%% enter_file(Path, FileName, IncludeLine, From, EppState)
%% leave_file(From, EppState)
%%  Handle entering and leaving included files. Notify caller when the
%%  current file is changed. Note it is an error to exit a file if we are
%%  in a conditional. These functions never return.

enter_file(_Path, _NewName, Li, From, St)
  when length(St#epp.sstk) >= 8 ->
    epp_reply(From, {error,{Li,epp,{depth,"include"}}}),
    wait_req_scan(St);
enter_file(Path, NewName, Li, From, St) ->
    case file:path_open(Path, NewName, read) of
	{ok,NewF,Pname} ->
	    wait_req_scan(enter_file2(NewF, Pname, From, St, 1));
	{error,_E} ->
	    epp_reply(From, {error,{Li,epp,{include,file,NewName}}}),
	    wait_req_scan(St)
    end.

%% enter_file2(File, FullName, From, EppState, AtLine) -> EppState.
%%  Set epp to use this file and "enter" it.

enter_file2(NewF, Pname, From, St, AtLine) ->
    enter_file2(NewF, Pname, From, St, AtLine, []).

enter_file2(NewF, Pname, From, St, AtLine, ExtraPath) ->
    enter_file_reply(From, Pname, 1, AtLine),
    Ms = dict:store({atom,'FILE'}, {none,[{string,1,Pname}]}, St#epp.macs),
    Path = St#epp.path ++ ExtraPath,
    #epp{file=NewF,name=Pname,sstk=[St|St#epp.sstk],path=Path,macs=Ms}.

enter_file_reply(From, Name, Line, AtLine) ->
    Rep = {ok, [{'-',AtLine},{atom,AtLine,file},{'(',AtLine},
		{string,AtLine,file_name(Name)},{',',AtLine},
		{integer,AtLine,Line},{')',Line},{dot,AtLine}]},
    epp_reply(From, Rep).

%% Flatten filename to a string. Must be a valid filename.

file_name([C | T]) when is_integer(C), C > 0, C =< 255 ->
    [C | file_name(T)];
file_name([H|T]) ->
    file_name(H) ++ file_name(T);
file_name([]) ->
    [];
file_name(N) when is_atom(N) ->
    atom_to_list(N).

leave_file(From, St) ->
    case St#epp.istk of
	[I|Cis] -> 
	    epp_reply(From,
		      {error,{St#epp.line,epp, {illegal,"unterminated",I}}}),
	    leave_file(wait_request(St),St#epp{istk=Cis});
	[] ->
	    case St#epp.sstk of
		[OldSt|Sts] ->
		    file:close(St#epp.file),
		    enter_file_reply(From, OldSt#epp.name, 
                                     OldSt#epp.line, OldSt#epp.line),
		    Ms = dict:store({atom,'FILE'},
				    {none,
				     [{string,OldSt#epp.line,OldSt#epp.name}]},
				    St#epp.macs),
		    wait_req_scan(OldSt#epp{sstk=Sts,macs=Ms});
		[] ->
		    epp_reply(From, {eof,St#epp.line}),
		    wait_req_scan(St)
	    end
    end.

%% scan_toks(From, EppState)
%% scan_toks(Tokens, From, EppState)

scan_toks(From, St) ->
    case io:scan_erl_form(St#epp.file, '', St#epp.line) of
	{ok,Toks,Cl} ->
	    scan_toks(Toks, From, St#epp{line=Cl});
	{error,E,Cl} ->
	    epp_reply(From, {error,E}),
	    wait_req_scan(St#epp{line=Cl});
	{eof,Cl} ->
	    leave_file(From, St#epp{line=Cl});
	{error,_E} ->
            epp_reply(From, {error,{St#epp.line,epp,cannot_parse}}),