%% ``Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions 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.''
%%
%% @private
%% @copyright Richard Carlsson 2001-2003. Portions created by Ericsson
%% are Copyright 1999, Ericsson Utvecklings AB. All Rights Reserved.
%% @author Richard Carlsson <[email protected]>
%% @see edoc
%% @end
%% @doc Tokeniser for EDoc. Based on the Erlang standard library module
%% {@link //stdlib/erl_scan}.
-module(edoc_scanner).
%% NOTE: the interface to this module is ancient and should be updated.
%% Please do not regard these exported functions as stable. Their
%% behaviour is described in the documentation of the module `erl_scan'.
%%
%% Since there are no `full stop' tokens in EDoc specifications, the
%% `tokens' function *always* returns `{more, Continuation}' unless an
%% error occurs.
-export([string/1,string/2,format_error/1]).
-import(lists, [reverse/1]).
string(Cs) -> string(Cs, 1).
string(Cs, StartPos) ->
case scan(Cs, StartPos) of
{ok,Toks} -> {ok,Toks,StartPos};
{error,E} -> {error,E,StartPos}
end.
%% format_error(Error)
%% Return a string describing the error.
format_error({string,Quote,Head}) ->
["unterminated string starting with " ++ io_lib:write_string(Head,Quote)];
format_error({illegal,Type}) -> io_lib:fwrite("illegal ~w", [Type]);
format_error(char) -> "unterminated character";
format_error(scan) -> "premature end";
format_error({base,Base}) -> io_lib:fwrite("illegal base '~w'", [Base]);
format_error(float) -> "bad float";
format_error(Other) -> io_lib:write(Other).
%% Reserved words, not atoms:
reserved('where') -> true;
reserved(_) -> false.
%% scan(CharList, StartPos)
%% This takes a list of characters and tries to tokenise them.
%%
%% The token list is built in reverse order (in a stack) to save appending
%% and then reversed when all the tokens have been collected. Most tokens
%% are built in the same way.
%%
%% Returns:
%% {ok,[Tok]}
%% {error,{ErrorPos,edoc_scanner,What}}
scan(Cs, Pos) ->
scan1(Cs, [], Pos).
%% scan1(Characters, TokenStack, Position)
%% Scan a list of characters into tokens.
scan1([$\n|Cs], Toks, Pos) -> % Newline
scan1(Cs, Toks, Pos+1);
scan1([C|Cs], Toks, Pos) when C >= 0, C =< $ -> % Skip blanks
scan1(Cs, Toks, Pos);
scan1([C|Cs], Toks, Pos) when C >= $a, C =< $z -> % Unquoted atom
scan_atom(C, Cs, Toks, Pos);
scan1([C|Cs], Toks, Pos) when C >= $0, C =< $9 -> % Numbers
scan_number(C, Cs, Toks, Pos);
scan1([$-,C| Cs], Toks, Pos) when C >= $0, C =< $9 -> % Signed numbers
scan_signed_number($-, C, Cs, Toks, Pos);
scan1([$+,C| Cs], Toks, Pos) when C >= $0, C =< $9 -> % Signed numbers
scan_signed_number($+, C, Cs, Toks, Pos);
scan1([C|Cs], Toks, Pos) when C >= $A, C =< $Z -> % Variables
scan_variable(C, Cs, Toks, Pos);
scan1([$_|Cs], Toks, Pos) -> % Variables
scan_variable($_, Cs, Toks, Pos);
scan1([$$|Cs], Toks, Pos) -> % Character constant
case scan_char_const(Cs, Toks, Pos) of
{ok, Result} ->
{ok, Result};
{error, truncated_char} ->
scan_error(char, Pos);
{error, illegal_character} ->
scan_error({illegal, char}, Pos)
end;
scan1([$'|Cs0], Toks, Pos) -> % Quoted atom
case scan_string(Cs0, $', Pos) of
{S,Cs1,Pos1} ->
case catch list_to_atom(S) of
A when is_atom(A) ->
scan1(Cs1, [{atom,Pos,A}|Toks], Pos1);
_Error -> scan_error({illegal,atom}, Pos)
end;
{error, premature_end} ->
scan_error({string,$',Cs0}, Pos);
{error, truncated_char} ->
scan_error(char, Pos);
{error, illegal_character} ->
scan_error({illegal, atom}, Pos)
end;
scan1([$"|Cs0], Toks, Pos) -> % String
case scan_string(Cs0, $", Pos) of
{S,Cs1,Pos1} ->
case Toks of
[{string, Pos0, S0} | Toks1] ->
scan1(Cs1, [{string, Pos0, S0 ++ S} | Toks1],
Pos1);
_ ->
scan1(Cs1, [{string,Pos,S}|Toks], Pos1)
end;
{error, premature_end} ->
scan_error({string,$",Cs0}, Pos);
{error, truncated_char} ->
scan_error(char, Pos);
{error, illegal_character} ->
scan_error({illegal, string}, Pos)
end;
%% Punctuation characters and operators, first recognise multiples.
scan1([$=,$>|Cs], Toks, Pos) ->
scan1(Cs, [{'=>',Pos}|Toks], Pos);
scan1([$<,$<|Cs], Toks, Pos) ->
scan1(Cs, [{'<<',Pos}|Toks], Pos);
scan1([$>,$>|Cs], Toks, Pos) ->
scan1(Cs, [{'>>',Pos}|Toks], Pos);
scan1([$-,$>|Cs], Toks, Pos) ->
scan1(Cs, [{'->',Pos}|Toks], Pos);
scan1([$:,$:|Cs], Toks, Pos) ->
scan1(Cs, [{'::',Pos}|Toks], Pos);
scan1([$/,$/|Cs], Toks, Pos) ->
scan1(Cs, [{'//',Pos}|Toks], Pos);
scan1([$.,$.,$.|Cs], Toks, Pos) ->
scan1(Cs, [{'...',Pos}|Toks], Pos);
scan1([$.,$.|Cs], Toks, Pos) ->
scan1(Cs, [{'..',Pos}|Toks], Pos);
scan1([C|Cs], Toks, Pos) -> % Punctuation character
P = list_to_atom([C]),
scan1(Cs, [{P,Pos}|Toks], Pos);
scan1([], Toks0, _Pos) ->
Toks = reverse(Toks0),
{ok,Toks}.
%% Note that `_' is not accepted as a variable token.
scan_variable(C, Cs, Toks, Pos) ->
{Wcs,Cs1} = scan_name(Cs, []),
W = [C|reverse(Wcs)],
case W of
"_" ->
scan1(Cs1, [{an_var,Pos,'_'}|Toks], Pos);
_ ->
case catch list_to_atom(W) of
A when is_atom(A) ->
scan1(Cs1, [{var,Pos,A}|Toks], Pos);
_ ->
scan_error({illegal,variable}, Pos)
end
end.
scan_atom(C, Cs, Toks, Pos) ->
{Wcs,Cs1} = scan_name(Cs, []),
W = [C|reverse(Wcs)],
case catch list_to_atom(W) of
A when is_atom(A) ->
case reserved(A) of
true ->
scan1(Cs1, [{A,Pos}|Toks], Pos);
false ->
scan1(Cs1, [{atom,Pos,A}|Toks], Pos)
end;
_ ->
scan_error({illegal,token}, Pos)
end.
%% scan_name(Cs) -> lists:splitwith(fun (C) -> name_char(C) end, Cs).
scan_name([C|Cs], Ncs) ->
case name_char(C) of
true ->
scan_name(Cs, [C|Ncs]);
false ->
{Ncs,[C|Cs]} % Must rebuild here, sigh!
end;
scan_name([], Ncs) ->
{Ncs,[]}.
name_char(C) when C >= $a, C =< $z -> true;
name_char(C) when C >= $\337, C =< $\377, C /= $\367 -> true;
name_char(C) when C >= $A, C =< $Z -> true;
name_char(C) when C >= $\300, C =< $\336, C /= $\327 -> true;
name_char(C) when C >= $0, C =< $9 -> true;
name_char($_) -> true;
name_char($@) -> true;
name_char(_) -> false.
%% scan_string(CharList, QuoteChar, Pos) ->
%% {StringChars,RestChars, NewPos}
scan_string(Cs, Quote, Pos) ->
scan_string(Cs, [], Quote, Pos).
scan_string([Quote|Cs], Scs, Quote, Pos) ->
{reverse(Scs),Cs,Pos};
scan_string([], _Scs, _Quote, _Pos) ->
{error, premature_end};
scan_string(Cs0, Scs, Quote, Pos) ->
case scan_char(Cs0, Pos) of
{C,Cs,Pos1} ->
%% Only build the string here
scan_string(Cs, [C|Scs], Quote, Pos1);
Error ->
Error
end.
%% Note that space characters are not allowed
scan_char_const([$\040 | _Cs0], _Toks, _Pos) ->
{error, illegal_character};
scan_char_const(Cs0, Toks, Pos) ->
case scan_char(Cs0, Pos) of
{C,Cs,Pos1} ->
scan1(Cs, [{char,Pos,C}|Toks], Pos1);
Error ->
Error
end.
%% {Character,RestChars,NewPos} = scan_char(Chars, Pos)
%% Read a single character from a string or character constant. The
%% pre-scan phase has checked for errors here.
%% Note that control characters are not allowed.
scan_char([$\\|Cs], Pos) ->
scan_escape(Cs, Pos);
scan_char([C | _Cs], _Pos) when C =< 16#1f ->
{error, illegal_character};
scan_char([C|Cs], Pos) ->
{C,Cs,Pos};
scan_char([], _Pos) ->
{error, truncated_char}.
%% The following conforms to Standard Erlang escape sequences.
scan_escape([O1, O2, O3 | Cs], Pos) when % \<1-3> octal digits
O1 >= $0, O1 =< $3, O2 >= $0, O2 =< $7, O3 >= $0, O3 =< $7 ->
Val = (O1*8 + O2)*8 + O3 - 73*$0,
{Val,Cs,Pos};
scan_escape([O1, O2 | Cs], Pos) when
O1 >= $0, O1 =< $7, O2 >= $0, O2 =< $7 ->
Val = (O1*8 + O2) - 9*$0,
{Val,Cs,Pos};
scan_escape([O1 | Cs], Pos) when
O1 >= $0, O1 =< $7 ->
{O1 - $0,Cs,Pos};
scan_escape([$^, C | Cs], Pos) -> % \^X -> CTL-X
if C >= $\100, C =< $\137 ->
{C - $\100,Cs,Pos};
true -> {error, illegal_control_character}
end;
scan_escape([C | Cs], Pos) ->
case escape_char(C) of
C1 when C1 > $\000 -> {C1,Cs,Pos};
_ -> {error, undefined_escape_sequence}
end;
scan_escape([], _Pos) ->
{error, truncated_char}.
%% Note that we return $\000 for undefined escapes.
escape_char($b) -> $\010; % \b = BS
escape_char($d) -> $\177; % \d = DEL
escape_char($e) -> $\033; % \e = ESC
escape_char($f) -> $\014; % \f = FF
escape_char($n) -> $\012; % \n = LF
escape_char($r) -> $\015; % \r = CR
escape_char($s) -> $\040; % \s = SPC
escape_char($t) -> $\011; % \t = HT
escape_char($v) -> $\013; % \v = VT
escape_char($\\) -> $\134; % \\ = \
escape_char($') -> $\047; % \' = '
escape_char($") -> $\042; % \" = "
escape_char(_C) -> $\000.
%% scan_number(Char, CharList, TokenStack, Pos)
%% We handle sign and radix notation:
%% [+-]<digits> - the digits in base [+-]10
%% [+-]<digits>.<digits>
%% [+-]<digits>.<digits>E+-<digits>
%% [+-]<digits>#<digits> - the digits read in base [+-]B
%%
%% Except for explicitly based integers we build a list of all the
%% characters and then use list_to_integer/1 or list_to_float/1 to
%% generate the value.
%% SPos == Start position
%% CPos == Current position
scan_number(C, Cs0, Toks, Pos) ->
{Ncs,Cs,Pos1} = scan_integer(Cs0, [C], Pos),
scan_after_int(Cs, Ncs, Toks, Pos, Pos1).
scan_signed_number(S, C, Cs0, Toks, Pos) ->
{Ncs,Cs,Pos1} = scan_integer(Cs0, [C, S], Pos),
scan_after_int(Cs, Ncs, Toks, Pos, Pos1).
scan_integer([C|Cs], Stack, Pos) when C >= $0, C =< $9 ->
scan_integer(Cs, [C|Stack], Pos);
scan_integer(Cs, Stack, Pos) ->
{Stack,Cs,Pos}.
scan_after_int([$.,C|Cs0], Ncs0, Toks, SPos, CPos) when C >= $0, C =< $9 ->
{Ncs,Cs,CPos1} = scan_integer(Cs0, [C,$.|Ncs0], CPos),
scan_after_fraction(Cs, Ncs, Toks, SPos, CPos1);
scan_after_int(Cs, Ncs, Toks, SPos, CPos) ->
N = list_to_integer(reverse(Ncs)),
scan1(Cs, [{integer,SPos,N}|Toks], CPos).
scan_after_fraction([$E|Cs], Ncs, Toks, SPos, CPos) ->
scan_exponent(Cs, [$E|Ncs], Toks, SPos, CPos);
scan_after_fraction([$e|Cs], Ncs, Toks, SPos, CPos) ->
scan_exponent(Cs, [$e|Ncs], Toks, SPos, CPos);
scan_after_fraction(Cs, Ncs, Toks, SPos, CPos) ->
case catch list_to_float(reverse(Ncs)) of
N when is_float(N) ->
scan1(Cs, [{float,SPos,N}|Toks], CPos);
_Error -> scan_error({illegal,float}, SPos)
end.
%% scan_exponent(CharList, NumberCharStack, TokenStack, StartPos, CurPos)
%% Generate an error here if E{+|-} not followed by any digits.
scan_exponent([$+|Cs], Ncs, Toks, SPos, CPos) ->
scan_exponent1(Cs, [$+|Ncs], Toks, SPos, CPos);
scan_exponent([$-|Cs], Ncs, Toks, SPos, CPos) ->
scan_exponent1(Cs, [$-|Ncs], Toks, SPos, CPos);
scan_exponent(Cs, Ncs, Toks, SPos, CPos) ->
scan_exponent1(Cs, Ncs, Toks, SPos, CPos).
scan_exponent1([C|Cs0], Ncs0, Toks, SPos, CPos) when C >= $0, C =< $9 ->
{Ncs,Cs,CPos1} = scan_integer(Cs0, [C|Ncs0], CPos),
case catch list_to_float(reverse(Ncs)) of
N when is_float(N) ->
scan1(Cs, [{float,SPos,N}|Toks], CPos1);
_Error -> scan_error({illegal,float}, SPos)
end;
scan_exponent1(_, _, _, _, CPos) ->
scan_error(float, CPos).
scan_error(In, Pos) ->
{error,{Pos,edoc_scanner,In}}.
