%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2000-2013. All Rights Reserved.
%%
%% 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 online 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.
%%
%% %CopyrightEnd%
%%
%% Purpose: Scanner for Core Erlang.
%% For handling ISO 8859-1 (Latin-1) we use the following type
%% information:
%%
%% 000 - 037 NUL - US control
%% 040 - 057 SPC - / punctuation
%% 060 - 071 0 - 9 digit
%% 072 - 100 : - @ punctuation
%% 101 - 132 A - Z uppercase
%% 133 - 140 [ - ` punctuation
%% 141 - 172 a - z lowercase
%% 173 - 176 { - ~ punctuation
%% 177 DEL control
%% 200 - 237 control
%% 240 - 277 NBSP - ¿ punctuation
%% 300 - 326 À - Ö uppercase
%% 327 × punctuation
%% 330 - 336 Ø - Þ uppercase
%% 337 - 366 ß - ö lowercase
%% 367 ÷ punctuation
%% 370 - 377 ø - ÿ lowercase
%%
%% Many punctuation characters region have special meaning. Must
%% watch using × \327, bvery close to x \170
-module(core_scan).
-export([string/1, string/2, format_error/1]).
-import(lists, [reverse/1]).
%% string([Char]) ->
%% string([Char], StartPos) ->
%% {ok, [Tok], EndPos} |
%% {error, {Pos,core_scan,What}, EndPos}
string(Cs) -> string(Cs, 1).
string(Cs, Sp) ->
%% Add an 'eof' to always get correct handling.
case string_pre_scan(Cs, [], Sp) of
{done,_,SoFar,Ep} -> %Got tokens
case scan(reverse(SoFar), Sp) of
{ok,Toks} -> {ok,Toks,Ep};
{error,E} -> {error,E,Ep}
end;
Other -> Other %An error has occurred
end.
%% string_pre_scan(Cs, SoFar0, StartPos) ->
%% {done,Rest,SoFar,EndPos} | {error,E,EndPos}.
string_pre_scan(Cs, SoFar0, Sp) ->
case pre_scan(Cs, SoFar0, Sp) of
{done,Rest,SoFar1,Ep} -> %Got complete tokens
{done,Rest,SoFar1,Ep};
{more,Rest,SoFar1,Ep} -> %Missing end token
string_pre_scan(Rest ++ eof, SoFar1, Ep);
Other -> Other %An error has occurred
end.
%% format_error(Error)
%% Return a string describing the error.
-spec format_error(term()) -> iolist().
format_error({string,Quote,Head}) ->
["unterminated " ++ string_thing(Quote) ++
" 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).
string_thing($') -> "atom"; %' stupid emacs
string_thing($") -> "string". %" stupid emacs
%% Re-entrant pre-scanner.
%%
%% If the input list of characters is insufficient to build a term the
%% scanner returns a request for more characters and a continuation to be
%% used when trying to build a term with more characters. To indicate
%% end-of-file the input character list should be replaced with 'eof'
%% as an empty list has meaning.
%%
%% When more characters are need inside a comment, string or quoted
%% atom, which can become rather long, instead of pushing the
%% characters read so far back onto RestChars to be reread, a special
%% reentry token is returned indicating the middle of a construct.
%% The token is the start character as an atom, '%', '"' and '\''.
%% pre_scan([Char], SoFar, StartPos) ->
%% {done,RestChars,ScannedChars,NewPos} |
%% {more,RestChars,ScannedChars,NewPos} |
%% {error,{ErrorPos,core_scan,Description},NewPos}.
%% Main pre-scan function. It has been split into 2 functions because of
%% efficiency, with a good indexing compiler it would be unnecessary.
pre_scan([C|Cs], SoFar, Pos) ->
pre_scan(C, Cs, SoFar, Pos);
pre_scan([], SoFar, Pos) ->
{more,[],SoFar,Pos};
pre_scan(eof, SoFar, Pos) ->
{done,eof,SoFar,Pos}.
%% pre_scan(Char, [Char], SoFar, Pos)
pre_scan($$, Cs0, SoFar0, Pos) ->
case pre_char(Cs0, [$$|SoFar0]) of
{Cs,SoFar} ->
pre_scan(Cs, SoFar, Pos);
more ->
{more,[$$|Cs0],SoFar0, Pos};
error ->
pre_error(char, Pos, Pos)
end;
pre_scan($', Cs, SoFar, Pos) ->
pre_string(Cs, $', '\'', Pos, [$'|SoFar], Pos);
pre_scan({'\'',Sp}, Cs, SoFar, Pos) -> %Re-entering quoted atom
pre_string(Cs, $', '\'', Sp, SoFar, Pos);
pre_scan($", Cs, SoFar, Pos) ->
pre_string(Cs, $", '"', Pos, [$"|SoFar], Pos);
pre_scan({'"',Sp}, Cs, SoFar, Pos) -> %Re-entering string
pre_string(Cs, $", '"', Sp, SoFar, Pos);
pre_scan($%, Cs, SoFar, Pos) ->
pre_comment(Cs, SoFar, Pos);
pre_scan('%', Cs, SoFar, Pos) -> %Re-entering comment
pre_comment(Cs, SoFar, Pos);
pre_scan($\n, Cs, SoFar, Pos) ->
pre_scan(Cs, [$\n|SoFar], Pos+1);
pre_scan(C, Cs, SoFar, Pos) ->
pre_scan(Cs, [C|SoFar], Pos).
%% pre_string([Char], Quote, Reent, StartPos, SoFar, Pos)
pre_string([Q|Cs], Q, _, _, SoFar, Pos) ->
pre_scan(Cs, [Q|SoFar], Pos);
pre_string([$\n|Cs], Q, Reent, Sp, SoFar, Pos) ->
pre_string(Cs, Q, Reent, Sp, [$\n|SoFar], Pos+1);
pre_string([$\\|Cs0], Q, Reent, Sp, SoFar0, Pos) ->
case pre_escape(Cs0, SoFar0) of
{Cs,SoFar} ->
pre_string(Cs, Q, Reent, Sp, SoFar, Pos);
more ->
{more,[{Reent,Sp},$\\|Cs0],SoFar0,Pos};
error ->
pre_string_error(Q, Sp, SoFar0, Pos)
end;
pre_string([C|Cs], Q, Reent, Sp, SoFar, Pos) ->
pre_string(Cs, Q, Reent, Sp, [C|SoFar], Pos);
pre_string([], _, Reent, Sp, SoFar, Pos) ->
{more,[{Reent,Sp}],SoFar,Pos};
pre_string(eof, Q, _, Sp, SoFar, Pos) ->
pre_string_error(Q, Sp, SoFar, Pos).
pre_string_error(Q, Sp, SoFar, Pos) ->
S = reverse(string:substr(SoFar, 1, string:chr(SoFar, Q)-1)),
pre_error({string,Q,string:substr(S, 1, 16)}, Sp, Pos).
pre_char([C|Cs], SoFar) -> pre_char(C, Cs, SoFar);
pre_char([], _) -> more;
pre_char(eof, _) -> error.
pre_char($\\, Cs, SoFar) ->
pre_escape(Cs, SoFar);
pre_char(C, Cs, SoFar) ->
{Cs,[C|SoFar]}.
pre_escape([$^|Cs0], SoFar) ->
case Cs0 of
[C3|Cs] ->
{Cs,[C3,$^,$\\|SoFar]};
[] -> more;
eof -> error
end;
pre_escape([C|Cs], SoFar) ->
{Cs,[C,$\\|SoFar]};
pre_escape([], _) -> more;
pre_escape(eof, _) -> error.
%% pre_comment([Char], SoFar, Pos)
%% Comments are replaced by one SPACE.
pre_comment([$\n|Cs], SoFar, Pos) ->
pre_scan(Cs, [$\n,$\s|SoFar], Pos+1); %Terminate comment
pre_comment([_|Cs], SoFar, Pos) ->
pre_comment(Cs, SoFar, Pos);
pre_comment([], SoFar, Pos) ->
{more,['%'],SoFar,Pos};
pre_comment(eof, Sofar, Pos) ->
pre_scan(eof, [$\s|Sofar], Pos).
pre_error(E, Epos, Pos) ->
{error,{Epos,core_scan,E}, Pos}.
%% 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,core_scan,What}}
scan(Cs, Pos) ->
scan1(Cs, [], Pos).
%% scan1(Characters, TokenStack, Position)
%% Scan a list of characters into tokens.
scan1([$\n|Cs], Toks, Pos) -> %Skip newline
scan1(Cs, Toks, Pos+1);
scan1([C|Cs], Toks, Pos) when C >= $\000, C =< $\s -> %Skip control chars
scan1(Cs, Toks, Pos);
scan1([C|Cs], Toks, Pos) when C >= $\200, C =< $\240 ->
scan1(Cs, Toks, Pos);
scan1([C|Cs], Toks, Pos) when C >= $a, C =< $z -> %Keywords
scan_key_word(C, Cs, Toks, Pos);
scan1([C|Cs], Toks, Pos) when C >= $ß, C =< $ÿ, C /= $÷ ->
scan_key_word(C, Cs, Toks, Pos);
scan1([C|Cs], Toks, Pos) when C >= $A, C =< $Z -> %Variables
scan_variable(C, Cs, Toks, Pos);
scan1([C|Cs], Toks, Pos) when C >= $À, C =< $Þ, C /= $× ->
scan_variable(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([$_|Cs], Toks, Pos) -> %_ variables
scan_variable($_, Cs, Toks, Pos);
scan1([$$|Cs0], Toks, Pos) -> %Character constant
{C,Cs,Pos1} = scan_char(Cs0, Pos),
scan1(Cs, [{char,Pos,C}|Toks], Pos1);
scan1([$'|Cs0], Toks, Pos) -> %Atom (always quoted)
{S,Cs1,Pos1} = scan_string(Cs0, $', Pos),
case catch list_to_atom(S) of
A when is_atom(A) ->
scan1(Cs1, [{atom,Pos,A}|Toks], Pos1);
_Error -> scan_error({illegal,atom}, Pos)
end;
scan1([$"|Cs0], Toks, Pos) -> %String
{S,Cs1,Pos1} = scan_string(Cs0, $", Pos),
scan1(Cs1, [{string,Pos,S}|Toks], Pos1);
%% 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([C|Cs], Toks, Pos) -> %Punctuation character
P = list_to_atom([C]),
scan1(Cs, [{P,Pos}|Toks], Pos);
scan1([], Toks0, _) ->
Toks = reverse(Toks0),
{ok,Toks}.
%% scan_key_word(FirstChar, CharList, Tokens, Pos)
%% scan_variable(FirstChar, CharList, Tokens, Pos)
scan_key_word(C, Cs0, Toks, Pos) ->
{Wcs,Cs} = scan_name(Cs0, []),
case catch list_to_atom([C|reverse(Wcs)]) of
Name when is_atom(Name) ->
scan1(Cs, [{Name,Pos}|Toks], Pos);
_Error -> scan_error({illegal,atom}, Pos)
end.
scan_variable(C, Cs0, Toks, Pos) ->
{Wcs,Cs} = scan_name(Cs0, []),
case catch list_to_atom([C|reverse(Wcs)]) of
Name when is_atom(Name) ->
scan1(Cs, [{var,Pos,Name}|Toks], Pos);
_Error -> scan_error({illegal,var}, 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 >= $ß, C =< $ÿ, C /= $÷ -> true;
name_char(C) when C >= $A, C =< $Z -> true;
name_char(C) when C >= $À, C =< $Þ, C /= $× -> true;
name_char(C) when C >= $0, C =< $9 -> true;
name_char($_) -> true;
name_char($@) -> true;
name_char(_) -> false.
%% scan_string(CharList, QuoteChar, Pos) -> {StringChars,RestChars,NewPos}.
scan_string(Cs, Q, Pos) ->
scan_string(Cs, [], Q, Pos).
scan_string([Q|Cs], Scs, Q, Pos) ->
{reverse(Scs),Cs,Pos};
scan_string([$\n|Cs], Scs, Q, Pos) ->
scan_string(Cs, [$\n|Scs], Q, Pos+1);
scan_string([$\\|Cs0], Scs, Q, Pos) ->
{C,Cs,Pos1} = scan_escape(Cs0, Pos),
scan_string(Cs, [C|Scs], Q, Pos1);
scan_string([C|Cs], Scs, Q, Pos) ->
scan_string(Cs, [C|Scs], Q, Pos).
%% scan_char(Chars, Pos) -> {Char,RestChars,NewPos}.
%% Read a single character from a character constant. The pre-scan
%% phase has checked for errors here.
scan_char([$\\|Cs], Pos) ->
scan_escape(Cs, Pos);
scan_char([$\n|Cs], Pos) -> %Newline
{$\n,Cs,Pos+1};
scan_char([C|Cs], Pos) ->
{C,Cs,Pos}.
scan_escape([O1,O2,O3|Cs], Pos) when %\<1-3> octal digits
O1 >= $0, O1 =< $7, 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
Val = C band 31,
{Val,Cs,Pos};
%scan_escape([$\n,C1|Cs],Pos) ->
% {C1,Cs,Pos+1};
%scan_escape([C,C1|Cs],Pos) when C >= $\000, C =< $\s ->
% {C1,Cs,Pos};
scan_escape([$\n|Cs],Pos) ->
{$\n,Cs,Pos+1};
scan_escape([C0|Cs],Pos) ->
C = escape_char(C0),
{C,Cs,Pos}.
escape_char($n) -> $\n; %\n = LF
escape_char($r) -> $\r; %\r = CR
escape_char($t) -> $\t; %\t = TAB
escape_char($v) -> $\v; %\v = VT
escape_char($b) -> $\b; %\b = BS
escape_char($f) -> $\f; %\f = FF
escape_char($e) -> $\e; %\e = ESC
escape_char($s) -> $\s; %\s = SPC
escape_char($d) -> $\d; %\d = DEL
escape_char(C) -> C.
%% scan_number(Char, CharList, TokenStack, Pos)
%% We can handle simple radix notation:
%% <digit>#<digits> - the digits read in that base
%% <digits> - the digits in base 10
%% <digits>.<digits>
%% <digits>.<digits>E+-<digits>
%%
%% 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) ->
case list_to_integer(reverse(Ncs)) of
Base when Base >= 2, Base =< 16 ->
scan_based_int(Cs, 0, Base, Toks, SPos, CPos);
Base ->
scan_error({base,Base}, CPos)
end;
scan_after_int(Cs, Ncs, Toks, SPos, CPos) ->
N = list_to_integer(reverse(Ncs)),
scan1(Cs, [{integer,SPos,N}|Toks], CPos).
scan_based_int([C|Cs], SoFar, Base, Toks, SPos, CPos) when
C >= $0, C =< $9, C < Base + $0 ->
Next = SoFar * Base + (C - $0),
scan_based_int(Cs, Next, Base, Toks, SPos, CPos);
scan_based_int([C|Cs], SoFar, Base, Toks, SPos, CPos) when
C >= $a, C =< $f, C < Base + $a - 10 ->
Next = SoFar * Base + (C - $a + 10),
scan_based_int(Cs, Next, Base, Toks, SPos, CPos);
scan_based_int([C|Cs], SoFar, Base, Toks, SPos, CPos) when
C >= $A, C =< $F, C < Base + $A - 10 ->
Next = SoFar * Base + (C - $A + 10),
scan_based_int(Cs, Next, Base, Toks, SPos, CPos);
scan_based_int(Cs, SoFar, _, Toks, SPos, CPos) ->
scan1(Cs, [{integer,SPos,SoFar}|Toks], CPos).
scan_after_fraction([$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,core_scan,In}}.
