%%%-------------------------------------------------------------------
%%% File:      erlydtl_scanner.slex
%%% @author    Andreas Stenius <kaos@astekk.se>
%%% @copyright 2013 Andreas Stenius
%%% @doc
%%% erlydtl scanner
%%% @end
%%%
%%% The MIT License
%%%
%%% Copyright (c) 2013 Andreas Stenius
%%%
%%% Permission is hereby granted, free of charge, to any person obtaining a copy
%%% of this software and associated documentation files (the "Software"), to deal
%%% in the Software without restriction, including without limitation the rights
%%% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
%%% copies of the Software, and to permit persons to whom the Software is
%%% furnished to do so, subject to the following conditions:
%%%
%%% The above copyright notice and this permission notice shall be included in
%%% all copies or substantial portions of the Software.
%%%
%%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
%%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
%%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
%%% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
%%% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
%%% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
%%% THE SOFTWARE.
%%%
%%% @since 2013-11-05 by Andreas Stenius
%%%
%%% Rules based on the original erlydtl_scanner by Robert Saccon and Evan Miller.
%%%-------------------------------------------------------------------

-module erlydtl_scanner.
-function scan.
-init_state in_text.
form -compile(nowarn_unused_vars) end.
form -export([resume/1, format_error/1]) end.
form \
-record(scanner_state, { \
          template=[], \
          scanned=[], \
          pos={1,1}, \
          state=in_text \
         }) \
end.

form \
resume(#scanner_state{ template=Template, scanned=Scanned, \
                       pos=Pos, state=State }) -> \
    scan(Template, Scanned, Pos, State) \
end.

%% Rule syntax: Prio Prefix|any|- InState[-]|any[+|-] [, Guard] : {: Body}|{[Action...,] NewState [until Closer]}.
%% `state-' means a state without a closer state.
%% Where Guard and Body are one erlang expression (see it as a begin ... end block): expr <erlang code...> end

%% Open tags
10 {{ in_text-: open_var, in_code until }}.
10 {% in_text-: open_tag, in_code until %}.
10 <!--{{ in_text-: open_var, in_code until }}-->.
10 <!--{% in_text-: open_tag, in_code until %}-->.

%% Comments
20 {# in_text-: in_comment until #}.
20 <!--{# in_text-: in_comment until #}-->.

%% `any+' will match the closer with the prefix..
30 #}--> any+: skip, in_text-.
30 #} any+: skip, in_text-.

%% must come before the `space any' rule
40 any in_comment: +comment_tag.
%% end comment rules

%% The rest is "just" text..
50 any in_text-: +string.

%% Quoted strings
60 \" in_code: string_literal, in_double_quote.
62 \" in_double_quote: +string_literal, in_code.
64 \\ in_double_quote: +string_literal, in_double_quote_escape.
66 any in_double_quote: +string_literal.
68 any in_double_quote_escape: +string_literal, in_double_quote.

60 \' in_code: string_literal-\", in_single_quote.
62 \' in_single_quote: +string_literal-\", in_code.
64 \\ in_single_quote: +string_literal, in_single_quote_escape.
66 any in_single_quote: +string_literal.
68 any in_single_quote_escape: +string_literal, in_single_quote.

%% Close tags
70 }}--> any+: close_var, in_text-.
70 %}--> any+: close_tag, in_text-.
72 }} any+: close_var, in_text-.
72 %} any+:
  expr \
    case S of \
      [{identifier,_,"mitabrev"}, {open_tag,_,'{%'}|Ss] -> \
        scan(T, [{string, {R, C + 2}, ""} | Ss], \
             {R, C + 2}, {in_verbatim, undefined}); \
      [{identifier,_,Tag}, {identifier,_,verbatim}, {open_tag,_,'{%'}|Ss] -> \
        scan(T, [{string, {R, C + 2}, ""} | Ss], \
             {R, C + 2}, {in_verbatim, Tag}); \
      _ -> scan(T, [{close_tag, P, "%}"} | post_process(S, close_tag)], \
                {R, C + 2}, in_text) \
    end \
  end.  

%% verbatim stuff
80 {% in_verbatim:
  expr scan(T, S, {R, C + 2}, {in_verbatim_code, {E, "%{"}}) end.
82 \s in_verbatim_code:
  expr \
    {Tag, Backtrack} = E, \
    scan(T, S, {R, C + 1}, {in_verbatim_code, {Tag, [$\ |Backtrack]}}) \
  end.
84 'endverbatim%}' in_verbatim_code,
  expr element(1, E) =:= undefined end:
  expr scan(T, S, {R, C + 13}, in_text) end.
86 'endverbatim ' in_verbatim_code:
  expr \
    {Tag, Backtrack} = E, \
    scan(T, S, {R, C + 12}, \
         {in_endverbatim_code, \
          {Tag, lists:reverse("endverbatim ", Backtrack), ""}}) \
  end.
88 \s in_endverbatim_code,
  expr element(3, E) =:= "" end:
  expr \
    {Tag, Backtrack, EndTag} = E, \
    scan(T, S, {R, C + 1}, \
         {in_endverbatim_code, \
          {Tag, [$\ |Backtrack], EndTag}}) \
  end.
90 any in_endverbatim_code,
  expr \
    H >= $a andalso H =< $z orelse \
    H >= $0 andalso H =< $9 orelse H =:= $_ end:
  expr \
    {Tag, Backtrack, EndTag} = E, \
    scan(T, S, {R, C + 1}, \
         {in_endverbatim_code, \
          {Tag, [H|Backtrack], [H|EndTag]}}) \
  end.
92 \s in_endverbatim_code,
  expr element(1, E) =:= element(3, E) end:
  expr \
    {Tag, Backtrack, Tag} = E, \
    scan(T, S, {R, C + 1}, \
         {in_endverbatim_code, \
          {Tag, [$\ |Backtrack], Tag}}) \
  end.
94 %} in_endverbatim_code,
  expr element(1, E) =:= element(3, E) end:
  expr scan(T, S, {R, C + 2}, (in_text)) end.
96 %} in_endverbatim_code,
  expr element(1, E) =:= undefined andalso \
        element(3, E) =:= "" end:
  expr scan(T, S, {R, C + 2}, in_text) end.
98 any in_endverbatim_code:
  expr \
    {Tag, Backtrack, _} = E, \
    scan(T, \
         case S of \
           [{string,_, L}=M|Ss] -> \
             [setelement(3, M, [H|Backtrack] ++ L)|Ss]; \
           _ -> [{string, P, [H|Backtrack]}|S] \
         end, \
         case H of $\n -> {R + 1, 1}; _ -> {R, C + 1} end, \
         {in_verbatim, Tag}) \
  end.
100 any in_verbatim_code:
  expr \
    {Tag, Backtrack} = E, \
    scan(T, \
         case S of \
           [{string,_, L}=M|Ss] -> \
             [setelement(3, M, [H|Backtrack] ++ L)|Ss]; \
           _ -> [{string, P, [H|Backtrack]}|S] \
         end, \
         case H of $\n -> {R + 1, 1}; _ -> {R, C + 1} end, \
         {in_verbatim, Tag}) \
  end.
102 any in_verbatim:
  expr \
    scan(T, \
         case S of \
           [{string,_, L}=M|Ss] -> \
             [setelement(3, M, [H|L])|Ss]; \
           _ -> [{string, P, [H]}|S] \
         end, \
         case H of $\n -> {R + 1, 1}; _ -> {R, C + 1} end, \
         {in_verbatim, E}) \
  end.


%% Get back to `in_code' on these tokens:
110 == any: ==, in_code.
110 != any: !=, in_code.
110 >= any: >=, in_code.
110 <= any: <=, in_code.
110 > any: >, in_code.
110 < any: <, in_code.
110 ( any: (, in_code.
110 ) any: ), in_code.
110 \, any: \,, in_code.
110 | any: |, in_code.
110 = any: =, in_code.
110 \: any: \:, in_code.
110 \. any: \., in_code.
110 \_( any: \_ \(, in_code.

%% Eat space (and get back to `in_code')
%% note that `any' here will match states *with* a closer, i.e. not `in_text'.
%% (`any-' would match any stateless state.)
110 \s any: skip, in_code.

120 any in_code,
  expr \
    (H >= $a andalso H =< $z) orelse \
    (H >= $A andalso H =< $Z) orelse \
     H == $_ \
  end: identifier, in_identifier.

122 any in_code,
  expr \
    (H >= $0 andalso H =< $9) orelse H == $- \
  end: number_literal, in_number.

124 any in_code: expr return_error({illegal_char, H}, P, [H|T], S, St) end.

130 any in_number, expr H >= $0 andalso H =< $9 end: +number_literal.
132 any in_number: expr return_error({illegal_char, H}, P, [H|T], S, St) end.

140 any in_identifier,
  expr \
    (H >= $a andalso H =< $z) orelse \
    (H >= $A andalso H =< $Z) orelse \
    (H >= $0 andalso H =< $9) orelse \
     H == $_ \
  end: +identifier, in_identifier.
142 any in_identifier: expr return_error({illegal_char, H}, P, [H|T], S, St) end.

200 : in_text- :
  expr \
    {ok, lists:reverse(post_process(S,eof))} \
  end.

202 : in_comment : expr return_error({eof, in_comment}, P) end.
204 : any : expr return_error({eof, in_code}, P) end.


%% Process tokens as we parse them

string: lists reverse.
string_literal: lists reverse.
comment_tag: lists reverse.
number_literal: lists reverse, list_to_integer.
open_var: to_atom.
close_var: to_atom.
open_tag: to_atom.
close_tag: to_atom.

open_tag identifier, close_tag: expr is_keyword(all, T) end.
open_tag identifier: expr is_keyword(open_tag, T) end.
identifier, close_tag: expr is_keyword(close_tag, T) end.
identifier: expr is_keyword(any, T) end.


%% Utility functions

form return_error(Error, P, T, S, St) -> \
  {error, \
    {P, erlydtl_scanner, Error}, \
    #scanner_state{ template=T, \
                    scanned=post_process(S, err), \
                    pos=P, state=St } \
  } \
end.

form return_error(Error, P) -> {error, {P, erlydtl_scanner, Error}} end.

form to_atom(L) when is_list(L) -> list_to_atom(L) end.
form to_keyword(L, P) -> {to_atom(L ++ "_keyword"), P, L} end.
form atomize(L, T) -> setelement(3, T, to_atom(L)) end.

form \
  is_keyword(Class, {_, _, L} = T) -> \
    L1 = lists:reverse(L), \
    case is_keyword(Class, L1) of \
      true -> to_keyword(L1, element(2, T)); \
      false -> atomize(L1, T) \
    end; \
  is_keyword([C|Cs], L) -> \
    is_keyword(C, L) orelse \
    is_keyword(Cs, L); \
  is_keyword(all, L) -> is_keyword([any, open, close], L); \
  is_keyword(open_tag, L) -> is_keyword([any, open], L); \
  is_keyword(close_tag, L) -> is_keyword([any, close], L); \
  \
  is_keyword(any, "in") -> true; \
  is_keyword(any, "not") -> true; \
  is_keyword(any, "or") -> true; \
  is_keyword(any, "and") -> true; \
  is_keyword(any, "as") -> true; \
  is_keyword(any, "by") -> true; \
  is_keyword(any, "with") -> true; \
  is_keyword(any, "from") -> true; \
  is_keyword(any, "count") -> true; \
  is_keyword(any, "context") -> true; \
  \
  is_keyword(close, "only") -> true; \
  is_keyword(close, "parsed") -> true; \
  is_keyword(close, "noop") -> true; \
  is_keyword(close, "reversed") -> true; \
  is_keyword(close, "openblock") -> true; \
  is_keyword(close, "closeblock") -> true; \
  is_keyword(close, "openvariable") -> true; \
  is_keyword(close, "closevariable") -> true; \
  is_keyword(close, "openbrace") -> true; \
  is_keyword(close, "closebrace") -> true; \
  is_keyword(close, "opencomment") -> true; \
  is_keyword(close, "closecomment") -> true; \
  \
  is_keyword(open, "autoescape") -> true; \
  is_keyword(open, "endautoescape") -> true; \
  is_keyword(open, "block") -> true; \
  is_keyword(open, "endblock") -> true; \
  is_keyword(open, "comment") -> true; \
  is_keyword(open, "endcomment") -> true; \
  is_keyword(open, "cycle") -> true; \
  is_keyword(open, "extends") -> true; \
  is_keyword(open, "filter") -> true; \
  is_keyword(open, "endfilter") -> true; \
  is_keyword(open, "firstof") -> true; \
  is_keyword(open, "for") -> true; \
  is_keyword(open, "empty") -> true; \
  is_keyword(open, "endfor") -> true; \
  is_keyword(open, "if") -> true; \
  is_keyword(open, "elif") -> true; \
  is_keyword(open, "else") -> true; \
  is_keyword(open, "endif") -> true; \
  is_keyword(open, "ifchanged") -> true; \
  is_keyword(open, "endifchanged") -> true; \
  is_keyword(open, "ifequal") -> true; \
  is_keyword(open, "endifequal") -> true; \
  is_keyword(open, "ifnotequal") -> true; \
  is_keyword(open, "endifnotequal") -> true; \
  is_keyword(open, "include") -> true; \
  is_keyword(open, "now") -> true; \
  is_keyword(open, "regroup") -> true; \
  is_keyword(open, "endregroup") -> true; \
  is_keyword(open, "spaceless") -> true; \
  is_keyword(open, "endspaceless") -> true; \
  is_keyword(open, "ssi") -> true; \
  is_keyword(open, "templatetag") -> true; \
  is_keyword(open, "widthratio") -> true; \
  is_keyword(open, "call") -> true; \
  is_keyword(open, "endwith") -> true; \
  is_keyword(open, "trans") -> true; \
  is_keyword(open, "blocktrans") -> true; \
  is_keyword(open, "endblocktrans") -> true; \
  is_keyword(open, "load") -> true; \
  is_keyword(open, "plural") -> true; \
  is_keyword(_, _) -> false \
end.

form format_error({illegal_char, C}) -> \
       io_lib:format("Illegal character '~s'", [[C]]); \
     format_error({eof, Where}) -> \
       io_lib:format("Unexpected end of file ~s", [format_where(Where)]) \
end.

form format_where(in_comment) -> "in comment"; \
     format_where(in_code) -> "in code block" \
end.