%% Copyright (c) 2008,2009 Robert Virding. All rights reserved.
%%
%% Redistribution and use in source and binary forms, with or without
%% modification, are permitted provided that the following conditions
%% are met:
%%
%% 1. Redistributions of source code must retain the above copyright
%% notice, this list of conditions and the following disclaimer.
%% 2. Redistributions in binary form must reproduce the above copyright
%% notice, this list of conditions and the following disclaimer in the
%% documentation and/or other materials provided with the distribution.
%%
%% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
%% "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
%% LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
%% FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
%% COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
%% INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
%% BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
%% LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
%% CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
%% LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
%% ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
%% POSSIBILITY OF SUCH DAMAGE.
%%% A Lexical Analyser Generator for Erlang.
%%%
%%% Most of the algorithms used here are taken pretty much as
%%% described in the "Dragon Book" by Aho, Sethi and Ullman. Some
%%% completing details were taken from "Compiler Design in C" by
%%% Hollub.
-module(leex).
-export([compile/3,file/1,file/2,format_error/1]).
-import(lists, [member/2,reverse/1,sort/1,delete/2,
keysort/2,keydelete/3,
map/2,foldl/3,foreach/2,flatmap/2]).
-import(string, [substr/2,substr/3,span/2]).
-import(ordsets, [is_element/2,add_element/2,union/2]).
-import(orddict, [store/3]).
-include("erl_compile.hrl").
%%-include_lib("stdlib/include/erl_compile.hrl").
-define(LEEXINC, "leexinc.hrl"). % Include file
-define(LEEXLIB, parsetools). % Leex is in lib parsetools
%%-define(LEEXLIB, leex). % Leex is in lib leex
-define(DEFS_HEAD, "Definitions.").
-define(RULE_HEAD, "Rules.").
-define(CODE_HEAD, "Erlang code.").
-record(leex, {xfile=[], % Xrl file
efile=[], % Erl file
ifile=[], % Include file
gfile=[], % Graph file
module, % Module name
opts=[], % Options
encoding=none, % Encoding of Xrl file
% posix=false, % POSIX regular expressions
errors=[],
warnings=[]
}).
-record(nfa_state, {no,edges=[],accept=noaccept}).
-record(dfa_state, {no,nfa=[],trans=[],accept=noaccept}).
%%%
%%% Exported functions
%%%
%%% Interface to erl_compile.
compile(Input0, Output0,
#options{warning = WarnLevel, verbose=Verbose, includes=Includes,
specific=Specific}) ->
Input = assure_extension(shorten_filename(Input0), ".xrl"),
Output = assure_extension(shorten_filename(Output0), ".erl"),
Includefile = lists:sublist(Includes, 1),
Werror = proplists:get_bool(warnings_as_errors, Specific),
Opts = [{scannerfile,Output},{includefile,Includefile},{verbose,Verbose},
{report_errors,true},{report_warnings,WarnLevel > 0},
{warnings_as_errors, Werror}],
case file(Input, Opts) of
{ok, _} ->
ok;
error ->
error
end.
%% file(File) -> ok | error.
%% file(File, Options) -> ok | error.
file(File) -> file(File, []).
file(File, Opts0) ->
case is_filename(File) of
no -> erlang:error(badarg, [File,Opts0]);
_ -> ok
end,
Opts = case options(Opts0) of
badarg ->
erlang:error(badarg, [File,Opts0]);
Options ->
Options
end,
St0 = #leex{},
St1 = filenames(File, Opts, St0), % Get all the filenames
St = try
{ok,REAs,Actions,Code,St2} = parse_file(St1),
{DFA,DF} = make_dfa(REAs, St2),
case werror(St2) of
false ->
St3 = out_file(St2, DFA, DF, Actions, Code),
case lists:member(dfa_graph, St3#leex.opts) of
true -> out_dfa_graph(St3, DFA, DF);
false -> St3
end;
true ->
St2
end
catch #leex{}=St4 ->
St4
end,
leex_ret(St).
format_error({file_error, Reason}) ->
io_lib:fwrite("~s",[file:format_error(Reason)]);
format_error(missing_defs) -> "missing Definitions";
format_error(missing_rules) -> "missing Rules";
format_error(missing_code) -> "missing Erlang code";
format_error(empty_rules) -> "no rules";
format_error(bad_rule) -> "bad rule";
format_error({regexp,E})->
Es = case E of
{interval_range,_} -> "interval range";
{unterminated,Cs} ->
"unterminated " ++ Cs;
{illegal_char,Cs} ->
"illegal character " ++ Cs;
%% {posix_cc,What} ->
%% ["illegal POSIX character class ",io_lib:write_string(What)];
{char_class,What} ->
["illegal character class ",io_lib:write_string(What)]
end,
["bad regexp `",Es,"'"];
format_error(ignored_characters) ->
"ignored characters";
format_error(cannot_parse) ->
io_lib:fwrite("cannot parse; probably encoding mismatch", []).
%%%
%%% Local functions
%%%
assure_extension(File, Ext) ->
lists:concat([strip_extension(File, Ext), Ext]).
%% Assumes File is a filename.
strip_extension(File, Ext) ->
case filename:extension(File) of
Ext -> filename:rootname(File);
_Other -> File
end.
options(Options0) when is_list(Options0) ->
try
Options = flatmap(fun(return) -> short_option(return, true);
(report) -> short_option(report, true);
({return,T}) -> short_option(return, T);
({report,T}) -> short_option(report, T);
(T) -> [T]
end, Options0),
options(Options, [scannerfile,includefile,report_errors,
report_warnings,warnings_as_errors,
return_errors,return_warnings,
verbose,dfa_graph], [])
catch error: _ -> badarg
end;
options(Option) ->
options([Option]).
short_option(return, T) ->
[{return_errors,T}, {return_warnings,T}];
short_option(report, T) ->
[{report_errors,T}, {report_warnings,T}].
options(Options0, [Key|Keys], L) when is_list(Options0) ->
Options = case member(Key, Options0) of
true ->
[atom_option(Key)|delete(Key, Options0)];
false ->
Options0
end,
V = case lists:keyfind(Key, 1, Options) of
{Key, Filename0} when Key =:= includefile;
Key =:= scannerfile ->
case is_filename(Filename0) of
no ->
badarg;
Filename ->
{ok,[{Key,Filename}]}
end;
{Key, Bool} = KB when is_boolean(Bool) ->
{ok, [KB]};
{Key, _} ->
badarg;
false ->
{ok,[{Key,default_option(Key)}]}
end,
case V of
badarg ->
badarg;
{ok,KeyValueL} ->
NewOptions = keydelete(Key, 1, Options),
options(NewOptions, Keys, KeyValueL ++ L)
end;
options([], [], L) ->
foldl(fun({_,false}, A) -> A;
({Tag,true}, A) -> [Tag|A];
(F,A) -> [F|A]
end, [], L);
options(_Options, _, _L) ->
badarg.
default_option(dfa_graph) -> false;
default_option(includefile) -> [];
default_option(report_errors) -> true;
default_option(report_warnings) -> true;
default_option(warnings_as_errors) -> false;
default_option(return_errors) -> false;
default_option(return_warnings) -> false;
default_option(scannerfile) -> [];
default_option(verbose) -> false.
atom_option(dfa_graph) -> {dfa_graph,true};
atom_option(report_errors) -> {report_errors,true};
atom_option(report_warnings) -> {report_warnings,true};
atom_option(warnings_as_errors) -> {warnings_as_errors,true};
atom_option(return_errors) -> {return_errors,true};
atom_option(return_warnings) -> {return_warnings,true};
atom_option(verbose) -> {verbose,true};
atom_option(Key) -> Key.
is_filename(T) ->
try filename:flatten(T)
catch error: _ -> no
end.
shorten_filename(Name0) ->
{ok,Cwd} = file:get_cwd(),
case lists:prefix(Cwd, Name0) of
false -> Name0;
true ->
case lists:nthtail(length(Cwd), Name0) of
"/"++N -> N;
N -> N
end
end.
leex_ret(St) ->
report_errors(St),
report_warnings(St),
Es = pack_errors(St#leex.errors),
Ws = pack_warnings(St#leex.warnings),
Werror = werror(St),
if
Werror ->
do_error_return(St, Es, Ws);
Es =:= [] ->
case member(return_warnings, St#leex.opts) of
true -> {ok, St#leex.efile, Ws};
false -> {ok, St#leex.efile}
end;
true ->
do_error_return(St, Es, Ws)
end.
do_error_return(St, Es, Ws) ->
case member(return_errors, St#leex.opts) of
true -> {error, Es, Ws};
false -> error
end.
werror(St) ->
St#leex.warnings =/= []
andalso member(warnings_as_errors, St#leex.opts).
pack_errors([{File,_} | _] = Es) ->
[{File, flatmap(fun({_,E}) -> [E] end, sort(Es))}];
pack_errors([]) ->
[].
pack_warnings([{File,_} | _] = Ws) ->
[{File, flatmap(fun({_,W}) -> [W] end, sort(Ws))}];
pack_warnings([]) ->
[].
report_errors(St) ->
when_opt(fun () ->
foreach(fun({File,{none,Mod,E}}) ->
io:fwrite("~s: ~ts\n",
[File,Mod:format_error(E)]);
({File,{Line,Mod,E}}) ->
io:fwrite("~s:~w: ~ts\n",
[File,Line,Mod:format_error(E)])
end, sort(St#leex.errors))
end, report_errors, St#leex.opts).
report_warnings(St) ->
Werror = member(warnings_as_errors, St#leex.opts),
Prefix = case Werror of
true -> "";
false -> "Warning: "
end,
ReportWerror = Werror andalso member(report_errors, St#leex.opts),
ShouldReport = member(report_warnings, St#leex.opts) orelse ReportWerror,
when_bool(fun () ->
foreach(fun({File,{none,Mod,W}}) ->
io:fwrite("~s: ~s~ts\n",
[File,Prefix,
Mod:format_error(W)]);
({File,{Line,Mod,W}}) ->
io:fwrite("~s:~w: ~s~ts\n",
[File,Line,Prefix,
Mod:format_error(W)])
end, sort(St#leex.warnings))
end, ShouldReport).
-spec add_error(_, #leex{}) -> no_return().
add_error(E, St) ->
add_error(St#leex.xfile, E, St).
add_error(File, Error, St) ->
throw(St#leex{errors = [{File,Error}|St#leex.errors]}).
add_warning(Line, W, St) ->
St#leex{warnings = [{St#leex.xfile,{Line,leex,W}}|St#leex.warnings]}.
%% filenames(File, Options, State) -> State.
%% The default output dir is the current directory unless an
%% explicit one has been given in the options.
filenames(File, Opts, St0) ->
Dir = filename:dirname(File),
Base = filename:basename(File, ".xrl"),
Xfile = filename:join(Dir, Base ++ ".xrl"),
Efile = Base ++ ".erl",
Gfile = Base ++ ".dot",
Module = list_to_atom(Base),
St1 = St0#leex{xfile=Xfile,
opts=Opts,
module=Module},
{includefile,Ifile0} = lists:keyfind(includefile, 1, Opts),
Ifile = inc_file_name(Ifile0),
%% Test for explicit scanner file.
{scannerfile,Ofile} = lists:keyfind(scannerfile, 1, Opts),
if
Ofile =:= [] ->
St1#leex{efile=filename:join(Dir, Efile),
ifile=Ifile,
gfile=filename:join(Dir, Gfile)};
true ->
D = filename:dirname(Ofile),
St1#leex{efile=Ofile,
ifile=Ifile,
gfile=filename:join(D, Gfile)}
end.
when_opt(Do, Opt, Opts) ->
case member(Opt, Opts) of
true -> Do();
false -> ok
end.
when_bool(Do, Bool) ->
case Bool of
true -> Do();
false -> ok
end.
verbose_print(St, Format, Args) ->
when_opt(fun () -> io:fwrite(Format, Args) end, verbose, St#leex.opts).
%% parse_file(State) -> {ok,[REA],[Action],Code,NewState} | throw(NewState)
%% when
%% REA = {RegExp,ActionNo};
%% Action = {ActionNo,ActionString};
%% Code = {StartLine, StartPos, NumOfLines}. Where the Erlang code is.
%%
%% Read and parse the file Xfile.
%% After each section of the file has been parsed we directly call the
%% next section. This is done when we detect a line we don't recognise
%% in the current section. The file format is very simple and Erlang
%% token based, we allow empty lines and Erlang style comments.
parse_file(St0) ->
case file:open(St0#leex.xfile, [read]) of
{ok,Xfile} ->
St1 = St0#leex{encoding = epp:set_encoding(Xfile)},
try
verbose_print(St1, "Parsing file ~s, ", [St1#leex.xfile]),
%% We KNOW that errors throw so we can ignore them here.
{ok,Line1,St2} = parse_head(Xfile, St1),
{ok,Line2,Macs,St3} = parse_defs(Xfile, Line1, St2),
{ok,Line3,REAs,Actions,St4} =
parse_rules(Xfile, Line2, Macs, St3),
{ok,Code,St5} = parse_code(Xfile, Line3, St4),
verbose_print(St5, "contained ~w rules.~n", [length(REAs)]),
{ok,REAs,Actions,Code,St5}
after ok = file:close(Xfile)
end;
{error,Error} ->
add_error({none,leex,{file_error,Error}}, St0)
end.
%% parse_head(File, State) -> {ok,NextLine,State}.
%% Parse the head of the file. Skip all comments and blank lines.
parse_head(Ifile, St) -> {ok,nextline(Ifile, 0, St),St}.
%% parse_defs(File, Line, State) -> {ok,NextLine,Macros,State}.
%% Parse the macro definition section of a file. This must exist.
%% The section is ended by a non-blank line which is not a macro def.
parse_defs(Ifile, {ok,?DEFS_HEAD ++ Rest,L}, St) ->
St1 = warn_ignored_chars(L, Rest, St),
parse_defs(Ifile, nextline(Ifile, L, St), [], St1);
parse_defs(_, {ok,_,L}, St) ->
add_error({L,leex,missing_defs}, St);
parse_defs(_, {eof,L}, St) ->
add_error({L,leex,missing_defs}, St).
parse_defs(Ifile, {ok,Chars,L}=Line, Ms, St) ->
%% This little beauty matches out a macro definition, RE's are so clear.
MS = "^[ \t]*([A-Z_][A-Za-z0-9_]*)[ \t]*=[ \t]*([^ \t\r\n]*)[ \t\r\n]*\$",
case re:run(Chars, MS, [{capture,all_but_first,list}]) of
{match,[Name,Def]} ->
%%io:fwrite("~p = ~p\n", [Name,Def]),
parse_defs(Ifile, nextline(Ifile, L, St), [{Name,Def}|Ms], St);
_ -> {ok,Line,Ms,St} % Anything else
end;
parse_defs(_, Line, Ms, St) ->
{ok,Line,Ms,St}.
%% parse_rules(File, Line, Macros, State) -> {ok,NextLine,REAs,Actions,State}.
%% Parse the RE rules section of the file. This must exist.
parse_rules(Ifile, {ok,?RULE_HEAD ++ Rest,L}, Ms, St) ->
St1 = warn_ignored_chars(L, Rest, St),
parse_rules(Ifile, nextline(Ifile, L, St), Ms, [], [], 0, St1);
parse_rules(_, {ok,_,L}, _, St) ->
add_error({L,leex,missing_rules}, St);
parse_rules(_, {eof,L}, _, St) ->
add_error({L,leex,missing_rules}, St).
%% parse_rules(File, Result, Macros, RegExpActions, Actions, Acount, State) ->
%% {ok,NextCLine,RegExpActions,Actions,NewState} | throw(NewState)
parse_rules(Ifile, NextLine, Ms, REAs, As, N, St) ->
case NextLine of
{ok,?CODE_HEAD ++ _Rest,_} ->
parse_rules_end(Ifile, NextLine, REAs, As, St);
{ok,Chars,L0} ->
%%io:fwrite("~w: ~p~n", [L0,Chars]),
case collect_rule(Ifile, Chars, L0) of
{ok,Re,Atoks,L1} ->
{ok,REA,A,St1} = parse_rule(Re, L0, Atoks, Ms, N, St),
parse_rules(Ifile, nextline(Ifile, L1, St), Ms,
[REA|REAs], [A|As], N+1, St1);
{error,E} -> add_error(E, St)
end;
{eof,_} ->
parse_rules_end(Ifile, NextLine, REAs, As, St)
end.
parse_rules_end(_, {ok,_,L}, [], [], St) ->
add_error({L,leex,empty_rules}, St);
parse_rules_end(_, {eof,L}, [], [], St) ->
add_error({L,leex,empty_rules}, St);
parse_rules_end(_, NextLine, REAs, As, St) ->
%% Must be *VERY* careful to put rules in correct order!
{ok,NextLine,reverse(REAs),reverse(As),St}.
%% collect_rule(File, Line, Lineno) ->
%% {ok,RegExp,ActionTokens,NewLineno} | {error,E}.
%% Collect a complete rule by reading lines until the the regexp and
%% action has been read. Keep track of line number.
collect_rule(Ifile, Chars, L0) ->
%% Erlang strings are 1 based, but re 0 :-(
{match,[{St0,Len}|_]} = re:run(Chars, "[^ \t\r\n]+"),
St = St0 + 1,
%%io:fwrite("RE = ~p~n", [substr(Chars, St, Len)]),
case collect_action(Ifile, substr(Chars, St+Len), L0, []) of
{ok,[{':',_}|Toks],L1} -> {ok,substr(Chars, St, Len),Toks,L1};
{ok,_,_} -> {error,{L0,leex,bad_rule}};
{eof,L1} -> {error,{L1,leex,bad_rule}};
{error,E,_} -> {error,E}
end.
collect_action(_Ifile, {error, _}, L, _Cont0) ->
{error, {L, leex, cannot_parse}, ignored_end_line};
collect_action(Ifile, Chars, L0, Cont0) ->
case erl_scan:tokens(Cont0, Chars, L0) of
{done,{ok,Toks,_},_} -> {ok,Toks,L0};
{done,{eof,_},_} -> {eof,L0};
{done,{error,E,_},_} -> {error,E,L0};
{more,Cont1} ->
collect_action(Ifile, io:get_line(Ifile, leex), L0+1, Cont1)
end.
%% parse_rule(RegExpString, RegExpLine, ActionTokens, Macros, Counter, State) ->
%% {ok,{RE,Action},ActionData,State}.
%% Parse one regexp after performing macro substition.
parse_rule(S, Line, [{dot,_}], Ms, N, St) ->
case parse_rule_regexp(S, Ms, St) of
{ok,R} ->
{ok,{R,N},{N,empty_action},St};
{error,E} ->
add_error({Line,leex,E}, St)
end;
parse_rule(S, Line, Atoks, Ms, N, St) ->
case parse_rule_regexp(S, Ms, St) of
{ok,R} ->
%%io:fwrite("RE = ~p~n", [R]),
%% Check for token variables.
TokenChars = var_used('TokenChars', Atoks),
TokenLen = var_used('TokenLen', Atoks),
TokenLine = var_used('TokenLine', Atoks),
{ok,{R,N},{N,Atoks,TokenChars,TokenLen,TokenLine},St};
{error,E} ->
add_error({Line,leex,E}, St)
end.
var_used(Name, Toks) ->
case lists:keyfind(Name, 3, Toks) of
{var,_,Name} -> true; %It's the var we want
_ -> false
end.
%% parse_rule_regexp(RegExpString, Macros, State) ->
%% {ok,RegExp} | {error,Error}.
%% Substitute in macros and parse RegExpString. Cannot use re:replace
%% here as it uses info in replace string (&).
parse_rule_regexp(RE0, [{M,Exp}|Ms], St) ->
Split= re:split(RE0, "\\{" ++ M ++ "\\}", [{return,list}]),
RE1 = string:join(Split, Exp),
parse_rule_regexp(RE1, Ms, St);
parse_rule_regexp(RE, [], St) ->
%%io:fwrite("RE = ~p~n", [RE]),
case re_parse(RE, St) of
{ok,R} -> {ok,R};
{error,E} -> {error,{regexp,E}}
end.
%% parse_code(File, Line, State) -> {ok,Code,NewState}.
%% Finds the line and the position where the code section of the file
%% begins. This must exist.
parse_code(Ifile, {ok,?CODE_HEAD ++ Rest,CodeL}, St) ->
St1 = warn_ignored_chars(CodeL, Rest, St),
{ok, CodePos} = file:position(Ifile, cur),
%% Just count the lines; copy the code from file to file later.
EndCodeLine = count_lines(Ifile, CodeL, St),
NCodeLines = EndCodeLine - CodeL,
{ok,{CodeL,CodePos,NCodeLines},St1};
parse_code(_, {ok,_,L}, St) ->
add_error({L,leex,missing_code}, St);
parse_code(_, {eof,L}, St) ->
add_error({L,leex,missing_code}, St).
count_lines(File, N, St) ->
case io:get_line(File, leex) of
eof -> N;
{error, _} -> add_error({N+1, leex, cannot_parse}, St);
_Line -> count_lines(File, N+1, St)
end.
%% nextline(InputFile, PrevLineNo, State) -> {ok,Chars,LineNo} | {eof,LineNo}.
%% Get the next line skipping comment lines and blank lines.
nextline(Ifile, L, St) ->
case io:get_line(Ifile, leex) of
eof -> {eof,L};
{error, _} -> add_error({L+1, leex, cannot_parse}, St);
Chars ->
case substr(Chars, span(Chars, " \t\n")+1) of
[$%|_Rest] -> nextline(Ifile, L+1, St);
[] -> nextline(Ifile, L+1, St);
_Other -> {ok,Chars,L+1}
end
end.
warn_ignored_chars(Line, S, St) ->
case non_white(S) of
[] -> St;
_ -> add_warning(Line, ignored_characters, St)
end.
non_white(S) ->
[C || C <- S, C > $\s, C < $\200 orelse C > $\240].
%% This is the regular expression grammar used. It is equivalent to the
%% one used in AWK, except that we allow ^ $ to be used anywhere and fail
%% in the matching.
%%
%% reg -> alt : '$1'.
%% alt -> seq "|" seq ... : {alt,['$1','$2'...]}.
%% seq -> repeat repeat ... : {seq,['$1','$2'...]}.
%% repeat -> repeat "*" : {kclosure,'$1'}.
%% repeat -> repeat "+" : {pclosure,'$1'}.
%% repeat -> repeat "?" : {optional,'$1'}.
%% repeat -> repeat "{" [Min],[Max] "}" : {interval,'$1',Min,Max}
%% repeat -> single : '$1'.
%% single -> "(" reg ")" : {sub,'$2',Number}.
%% single -> "^" : bos/bol.
%% single -> "$" : eos/eol.
%% single -> "." : any.
%% single -> "[" class "]" : {char_class,char_class('$2')}
%% single -> "[" "^" class "]" : {comp_class,char_class('$3')}.
%% single -> "\"" chars "\"" : {lit,'$2'}.
%% single -> "\\" char : {lit,['$2']}.
%% single -> char : {lit,['$1']}.
%% single -> empty : epsilon.
%% The grammar of the current regular expressions. The actual parser
%% is a recursive descent implementation of the grammar.
%% re_parse(Chars, State) -> {ok,RegExp} | {error,Error}.
re_parse(Cs0, St) ->
case catch re_reg(Cs0, 0, St) of
{RE,_,[]} -> {ok,RE};
{_,_,[C|_]} -> {error,{illegal_char,[C]}};
{parse_error,E} -> {error,E}
end.
parse_error(E) -> throw({parse_error,E}).
re_reg(Cs, Sn, St) -> re_alt(Cs, Sn, St).
re_alt(Cs0, Sn0, St) ->
{L,Sn1,Cs1} = re_seq(Cs0, Sn0, St),
case re_alt1(Cs1, Sn1, St) of
{[],Sn2,Cs2} -> {L,Sn2,Cs2};
{Rs,Sn2,Cs2} -> {{alt,[L|Rs]},Sn2,Cs2}
end.
re_alt1([$||Cs0], Sn0, St) ->
{L,Sn1,Cs1} = re_seq(Cs0, Sn0, St),
{Rs,Sn2,Cs2} = re_alt1(Cs1, Sn1, St),
{[L|Rs],Sn2,Cs2};
re_alt1(Cs, Sn, _) -> {[],Sn,Cs}.
%% Parse a sequence of regexps. Don't allow the empty sequence.
%% re_seq(Cs0, Sn0, St) ->
%% {L,Sn1,Cs1} = repeat(Cs0, Sn0, St),
%% case re_seq1(Cs1, Sn1, St) of
%% {[],Sn2,Cs2} -> {L,Sn2,Cs2};
%% {Rs,Sn2,Cs2} -> {{seq,[L|Rs]},Sn2,Cs2}
%% end.
%% re_seq(Chars, SubNumber, State) -> {RegExp,SubNumber,Chars}.
%% Parse a sequence of regexps. Allow the empty sequence, returns epsilon.
re_seq(Cs0, Sn0, St) ->
case re_seq1(Cs0, Sn0, St) of
{[],Sn1,Cs1} -> {epsilon,Sn1,Cs1};
{[R],Sn1,Cs1} -> {R,Sn1,Cs1};
{Rs,Sn1,Cs1} -> {{seq,Rs},Sn1,Cs1}
end.
re_seq1([C|_]=Cs0, Sn0, St) when C =/= $|, C =/= $) ->
{L,Sn1,Cs1} = re_repeat(Cs0, Sn0, St),
{Rs,Sn2,Cs2} = re_seq1(Cs1, Sn1, St),
{[L|Rs],Sn2,Cs2};
re_seq1(Cs, Sn, _) -> {[],Sn,Cs}.
%% re_repeat(Chars, SubNumber, State) -> {RegExp,SubNumber,Chars}.
re_repeat(Cs0, Sn0, St) ->
{S,Sn1,Cs1} = re_single(Cs0, Sn0, St),
re_repeat1(Cs1, Sn1, S, St).
re_repeat1([$*|Cs], Sn, S, St) -> re_repeat1(Cs, Sn, {kclosure,S}, St);
re_repeat1([$+|Cs], Sn, S, St) -> re_repeat1(Cs, Sn, {pclosure,S}, St);
re_repeat1([$?|Cs], Sn, S, St) -> re_repeat1(Cs, Sn, {optional,S}, St);
%% { only starts interval when ere is true, otherwise normal character.
%% re_repeat1([${|Cs0], Sn, S, #leex{posix=true}=St) -> % $}
%% case re_interval_range(Cs0) of
%% {Min,Max,[$}|Cs1]} when is_integer(Min), is_integer(Max), Min =< Max ->
%% re_repeat1(Cs1, Sn, {interval,S,Min,Max}, St);
%% {Min,Max,[$}|Cs1]} when is_integer(Min), is_atom(Max) ->
%% re_repeat1(Cs1, Sn, {interval,S,Min,Max}, St);
%% {_,_,Cs1} -> parse_error({interval_range,string_between([${|Cs0], Cs1)})
%% end;
re_repeat1(Cs, Sn, S, _) -> {S,Sn,Cs}.
%% re_single(Chars, SubNumber, State) -> {RegExp,SubNumber,Chars}.
%% Parse a re_single regexp.
re_single([$(|Cs0], Sn0, St) -> % $)
Sn1 = Sn0 + 1, % Keep track of sub count anyway
case re_reg(Cs0, Sn1, St) of
{S,Sn2,[$)|Cs1]} -> {S,Sn2,Cs1};
%%{S,Sn2,[$)|Cs1]} -> {{sub,S,Sn1},Sn2,Cs1};
_ -> parse_error({unterminated,"("})
end;
%% These are not legal inside a regexp.
%% re_single([$^|Cs], Sn, St) -> {bos,Sn,Cs};
%% re_single([$$|Cs], Sn, St) -> {eos,Sn,Cs};
%% re_single([$.|Cs], Sn, St) -> {any,Sn,Cs};
re_single([$.|Cs], Sn, _) -> {{comp_class,"\n"},Sn,Cs}; % Do this here?
re_single("[^" ++ Cs0, Sn, St) ->
case re_char_class(Cs0, St) of
{Cc,[$]|Cs1]} -> {{comp_class,Cc},Sn,Cs1};
_ -> parse_error({unterminated,"["})
end;
re_single([$[|Cs0], Sn, St) ->
case re_char_class(Cs0, St) of
{Cc,[$]|Cs1]} -> {{char_class,Cc},Sn,Cs1};
_ -> parse_error({unterminated,"["})
end;
re_single([$\\|Cs0], Sn, _) ->
{C,Cs1} = re_char($\\, Cs0),
{{lit,[C]},Sn,Cs1};
re_single([C|Cs0], Sn, St) ->
case special_char(C, St) of
true -> parse_error({illegal_char,[C]});
false ->
{C,Cs1} = re_char(C, Cs0),
{{lit,[C]},Sn,Cs1}
end.
-define(IS_HEX(C), C >= $0 andalso C =< $9 orelse
C >= $A andalso C =< $F orelse
C >= $a andalso C =< $f).
%% re_char(Char, Chars) -> {CharValue,Chars}.
%% Reads one character value from the input list, it knows about escapes.
re_char($\\, [O1,O2,O3|S]) when
O1 >= $0, O1 =< $7, O2 >= $0, O2 =< $7, O3 >= $0, O3 =< $7 ->
{(O1*8 + O2)*8 + O3 - 73*$0,S};
re_char($\\, [$x,H1,H2|S]) when ?IS_HEX(H1), ?IS_HEX(H2) ->
{erlang:list_to_integer([H1,H2], 16),S};
re_char($\\,[$x,${|S0]) ->
re_hex(S0, []);
re_char($\\,[$x|_]) ->
parse_error({illegal_char,"\\x"});
re_char($\\, [C|S]) -> {escape_char(C),S};
re_char($\\, []) -> parse_error({unterminated,"\\"});
re_char(C, S) -> {C,S}. % Just this character
re_hex([C|Cs], L) when ?IS_HEX(C) -> re_hex(Cs, [C|L]);
re_hex([$}|S], L0) ->
L = lists:reverse(L0),
case erlang:list_to_integer(L, 16) of
C when C =< 16#10FFFF -> {C,S};
_ -> parse_error({illegal_char,[$\\,$x,${|L]++"}"})
end;
re_hex(_, _) -> parse_error({unterminated,"\\x{"}).
%% special_char(Char, State) -> bool().
%% These are the special characters for an ERE.
%% N.B. ]}) are only special in the context after [{(.
special_char($^, _) -> true;
special_char($., _) -> true;
special_char($[, _) -> true;
special_char($$, _) -> true;
special_char($(, _) -> true;
special_char($), _) -> true;
special_char($|, _) -> true;
special_char($*, _) -> true;
special_char($+, _) -> true;
special_char($?, _) -> true;
%% special_char(${, #leex{posix=true}) -> true; % Only when POSIX set
special_char($\\, _) -> true;
special_char(_, _) -> false.
%% re_char_class(Chars, State) -> {CharClass,Chars}.
%% Parse a character class.
re_char_class([$]|Cs], St) -> % Must special case this.
re_char_class(Cs, [$]], St);
re_char_class(Cs, St) -> re_char_class(Cs, [], St).
%% re_char_class("[:" ++ Cs0, Cc, #leex{posix=true}=St) ->
%% %% POSIX char class only.
%% case posix_cc(Cs0) of
%% {Pcl,":]" ++ Cs1} -> re_char_class(Cs1, [{posix,Pcl}|Cc], St);
%% {_,Cs1} -> parse_error({posix_cc,string_between(Cs0, Cs1)})
%% end;
re_char_class([C1|Cs0], Cc, St) when C1 =/= $] ->
case re_char(C1, Cs0) of
{Cf,[$-,C2|Cs1]} when C2 =/= $] ->
case re_char(C2, Cs1) of
{Cl,Cs2} when Cf < Cl ->
re_char_class(Cs2, [{range,Cf,Cl}|Cc], St);
{_,Cs2} ->
parse_error({char_class,string_between([C1|Cs0], Cs2)})
end;
{C,Cs1} -> re_char_class(Cs1, [C|Cc], St)
end;
re_char_class(Cs, Cc, _) -> {reverse(Cc),Cs}. % Preserve order
%% posix_cc(String) -> {PosixClass,RestString}.
%% Handle POSIX character classes.
%% posix_cc("alnum" ++ Cs) -> {alnum,Cs};
%% posix_cc("alpha" ++ Cs) -> {alpha,Cs};
%% posix_cc("blank" ++ Cs) -> {blank,Cs};
%% posix_cc("cntrl" ++ Cs) -> {cntrl,Cs};
%% posix_cc("digit" ++ Cs) -> {digit,Cs};
%% posix_cc("graph" ++ Cs) -> {graph,Cs};
%% posix_cc("lower" ++ Cs) -> {lower,Cs};
%% posix_cc("print" ++ Cs) -> {print,Cs};
%% posix_cc("punct" ++ Cs) -> {punct,Cs};
%% posix_cc("space" ++ Cs) -> {space,Cs};
%% posix_cc("upper" ++ Cs) -> {upper,Cs};
%% posix_cc("xdigit" ++ Cs) -> {xdigit,Cs};
%% posix_cc(Cs) -> parse_error({posix_cc,substr(Cs, 1, 5)}).
escape_char($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) -> $\s; % \s = SPACE
escape_char($d) -> $\d; % \d = DEL
escape_char(C) -> C. % Pass it straight through
%% re_interval_range(Chars) -> {Min,Max,RestChars}.
%% NoInt -> none,none
%% Int -> Int,none
%% Int, -> Int,any
%% Int1,Int2 -> Int1,Int2
%% re_interval_range(Cs0) ->
%% case re_number(Cs0) of
%% {none,Cs1} -> {none,none,Cs1};
%% {N,[$,|Cs1]} ->
%% case re_number(Cs1) of
%% {none,Cs2} -> {N,any,Cs2};
%% {M,Cs2} -> {N,M,Cs2}
%% end;
%% {N,Cs1} -> {N,none,Cs1}
%% end.
%% re_number([C|Cs]) when C >= $0, C =< $9 ->
%% re_number(Cs, C - $0);
%% re_number(Cs) -> {none,Cs}.
%% re_number([C|Cs], Acc) when C >= $0, C =< $9 ->
%% re_number(Cs, 10*Acc + (C - $0));
%% re_number(Cs, Acc) -> {Acc,Cs}.
string_between(Cs1, Cs2) ->
substr(Cs1, 1, length(Cs1)-length(Cs2)).
%% We use standard methods, Thompson's construction and subset
%% construction, to create first an NFA and then a DFA from the
%% regexps. A non-standard feature is that we work with sets of
%% character ranges (crs) instead sets of characters. This is most
%% noticeable when constructing DFAs. The major benefit is that we can
%% handle characters from any set, not just limited ASCII or 8859,
%% even 16/32 bit unicode.
%%
%% The whole range of characters is 0-maxchar, where maxchar is a BIG
%% number. We don't make any assumptions about the size of maxchar, it
%% is just bigger than any character.
%%
%% Using character ranges makes describing many regexps very simple,
%% for example the regexp "." just becomes the range
%% [{0-9},{11-maxchar}].
%% make_nfa(RegExpActions) -> {ok,{NFA,StartState}} | {error,E}.
%% Build a complete nfa from a list of {RegExp,Action}. The NFA field
%% accept has values {yes,Action}|no. The NFA is a list of states.
make_dfa(REAs, St) ->
{NFA,NF} = build_combined_nfa(REAs),
verbose_print(St, "NFA contains ~w states, ", [tuple_size(NFA)]),
{DFA0,DF0} = build_dfa(NFA, NF),
verbose_print(St, "DFA contains ~w states, ", [length(DFA0)]),
{DFA,DF} = minimise_dfa(DFA0, DF0),
verbose_print(St, "minimised to ~w states.~n", [length(DFA)]),
%%io:fwrite("~p\n", [{NF,NFA}]),
%%io:fwrite("~p\n", [{DF0,DFA0}]),
%%io:fwrite("~p\n", [{DF,DFA}]),
{DFA,DF}.
%% build_combined_nfa(RegExpActionList) -> {NFA,FirstState}.
%% Build the combined NFA using Thompson's construction straight out
%% of the book. Build the separate NFAs in the same order as the
%% rules so that the accepting have ascending states have ascending
%% state numbers. Start numbering the states from 1 as we put the
%% states in a tuple with the state number as the index.
%%
%% The edges from a state are a list of {CharRange,State} | {epsilon,State}.
build_combined_nfa(REAs) ->
{NFA0,Firsts,Free} = build_nfa_list(REAs, [], [], 1),
F = #nfa_state{no=Free,edges=epsilon_trans(Firsts)},
{list_to_tuple(keysort(#nfa_state.no, [F|NFA0])),Free}.
build_nfa_list([{RE,Action}|REAs], NFA0, Firsts, Free0) ->
{NFA1,Free1,First} = build_nfa(RE, Free0, Action),
build_nfa_list(REAs, NFA1 ++ NFA0, [First|Firsts], Free1);
build_nfa_list([], NFA, Firsts, Free) ->
{NFA,reverse(Firsts),Free}.
epsilon_trans(Firsts) -> [ {epsilon,F} || F <- Firsts ].
%% build_nfa(RegExp, NextState, Action) -> {NFA,NextState,FirstState}.
%% When building the NFA states for a regexp we don't build the end
%% state, just allocate a State for it and return this state's
%% number. This allows us to avoid building unnecessary states for
%% concatenation which would then have to be removed by overwriting
%% an existing state.
build_nfa(RE, N0, Action) ->
{NFA,N1,E} = build_nfa(RE, N0+1, N0, []),
{[#nfa_state{no=E,accept={accept,Action}}|NFA],N1,N0}.
%% build_nfa(RegExp, NextState, FirstState, NFA) -> {NFA,NextState,EndState}.
%% Build an NFA from the RegExp. NFA is a list of #nfa_state{} in no
%% predefined order. NextState is the number of the next free state
%% to use, FirstState is the the state which must be the start for
%% this regexp as a previous regexp refers to it, EndState is the
%% state to which this NFA will exit to. The number of the returned
%% EndState is already allocated!
build_nfa({alt,REs}, N, F, NFA) ->
build_nfa_alt(REs, N, F, NFA);
build_nfa({seq,REs}, N, F, NFA) ->
build_nfa_seq(REs, N, F, NFA);
build_nfa({kclosure,RE}, N0, F, NFA0) ->
{NFA1,N1,E1} = build_nfa(RE, N0+1, N0, NFA0),
E = N1, % End state
{[#nfa_state{no=F,edges=[{epsilon,N0},{epsilon,E}]},
#nfa_state{no=E1,edges=[{epsilon,N0},{epsilon,E}]}|NFA1],
N1+1,E};
build_nfa({pclosure,RE}, N0, F, NFA0) ->
{NFA1,N1,E1} = build_nfa(RE, N0+1, N0, NFA0),
E = N1, % End state
{[#nfa_state{no=F,edges=[{epsilon,N0}]},
#nfa_state{no=E1,edges=[{epsilon,N0},{epsilon,E}]}|NFA1],
N1+1,E};
build_nfa({optional,RE}, N0, F, NFA0) ->
{NFA1,N1,E1} = build_nfa(RE, N0+1, N0, NFA0),
E = N1, % End state
{[#nfa_state{no=F,edges=[{epsilon,N0},{epsilon,E}]},
#nfa_state{no=E1,edges=[{epsilon,E}]}|NFA1],
N1+1,E};
build_nfa({char_class,Cc}, N, F, NFA) ->
{[#nfa_state{no=F,edges=[{pack_cc(Cc),N}]}|NFA],N+1,N};
build_nfa({comp_class,Cc}, N, F, NFA) ->
{[#nfa_state{no=F,edges=[{comp_class(Cc),N}]}|NFA],N+1,N};
build_nfa({lit,Cs}, N, F, NFA) -> % Implicit concatenation
build_nfa_lit(Cs, N, F, NFA);
build_nfa(epsilon, N, F, NFA) -> % Just an epsilon transition
{[#nfa_state{no=F,edges=[{epsilon,N}]}|NFA],N+1,N}.
%% build_nfa_lit(Chars, NextState, FirstState, NFA) -> {NFA,NextState,EndState}.
%% Build an NFA for the sequence of literal characters.
build_nfa_lit(Cs, N0, F0, NFA0) ->
foldl(fun (C, {NFA,N,F}) ->
{[#nfa_state{no=F,edges=[{[{C,C}],N}]}|NFA],N+1,N}
end, {NFA0,N0,F0}, Cs).
%% build_nfa_lit([C|Cs], N, F, NFA0) when is_integer(C) ->
%% NFA1 = [#nfa_state{no=F,edges=[{[{C,C}],N}]}|NFA0],
%% build_nfa_lit(Cs, N+1, N, NFA1);
%% build_nfa_lit([], N, F, NFA) -> {NFA,N,F}.
%% build_nfa_seq(REs, NextState, FirstState, NFA) -> {NFA,NextState,EndState}.
%% Build an NFA for the regexps in a sequence.
build_nfa_seq(REs, N0, F0, NFA0) ->
foldl(fun (RE, {NFA,N,F}) -> build_nfa(RE, N, F, NFA) end,
{NFA0,N0,F0}, REs).
%% build_nfa_seq([RE|REs], N0, F, NFA0) ->
%% {NFA1,N1,E1} = build_nfa(RE, N0, F, NFA0),
%% build_nfa_seq(REs, N1, E1, NFA1);
%% build_nfa_seq([], N, F, NFA) -> {NFA,N,F}.
%% build_nfa_alt(REs, NextState, FirstState, NFA) -> {NFA,NextState,EndState}.
%% Build an NFA for the regexps in an alternative. N.B. we don't
%% handle empty alts here but the parser should never generate them
%% anyway.
build_nfa_alt([RE], N, F, NFA) -> build_nfa(RE, N, F, NFA);
build_nfa_alt([RE|REs], N0, F, NFA0) ->
{NFA1,N1,E1} = build_nfa(RE, N0+1, N0, NFA0),
{NFA2,N2,E2} = build_nfa_alt(REs, N1+1, N1, NFA1),
E = N2, % End state
{[#nfa_state{no=F,edges=[{epsilon,N0},{epsilon,N1}]},
#nfa_state{no=E1,edges=[{epsilon,E}]},
#nfa_state{no=E2,edges=[{epsilon,E}]}|NFA2],
N2+1,E}.
%% build_nfa_alt(REs, NextState, FirstState, NFA) -> {NFA,NextState,EndState}.
%% Build an NFA for the regexps in an alternative. Make one big
%% epsilon split state, not necessary but fun.
%% build_nfa_alt(REs, N0, F0, NFA0) ->
%% E = N0, % Must reserve End state first
%% {Fs,{NFA1,N1}} = mapfoldl(fun (RE, {NFA,N}) ->
%% build_nfa_alt1(RE, N, E, NFA)
%% end, {NFA0,N0+1}, REs),
%% {[#nfa_state{no=F0,edges=epsilon_trans(Fs)},
%% #nfa_state{no=E,edges=[{epsilon,N1}]}|NFA1],N1+1,N1}.
%% build_nfa_alt1(RE, N0, End, NFA0) ->
%% {NFA1,N1,E} = build_nfa(RE, N0+1, N0, NFA0),
%% {N0,{[#nfa_state{no=E,edges=[{epsilon,End}]}|NFA1],N1}}.
%% pack_cc(CharClass) -> CharClass
%% Pack and optimise a character class specification (bracket
%% expression). First sort it and then compact it.
pack_cc(Cc) ->
Crs = foldl(fun ({range,Cf,Cl}, Set) -> add_element({Cf,Cl}, Set);
(C, Set) -> add_element({C,C}, Set)
end, ordsets:new(), Cc),
pack_crs(Crs). % An ordset IS a list!
pack_crs([{C1,C2}=Cr,{C3,C4}|Crs]) when C1 =< C3, C2 >= C4 ->
%% C1 C2
%% C3 C4
pack_crs([Cr|Crs]);
pack_crs([{C1,C2},{C3,C4}|Crs]) when C2 >= C3, C2 < C4 ->
%% C1 C2
%% C3 C4
pack_crs([{C1,C4}|Crs]);
pack_crs([{C1,C2},{C3,C4}|Crs]) when C2 + 1 =:= C3 ->
%% C1 C2
%% C3 C4
pack_crs([{C1,C4}|Crs]);
pack_crs([Cr|Crs]) -> [Cr|pack_crs(Crs)];
pack_crs([]) -> [].
comp_class(Cc) ->
Crs = pack_cc(Cc),
Comp = comp_crs(Crs, 0),
%% io:fwrite("comp: ~p\n ~p\n", [Crs,Comp]),
Comp.
comp_crs([{0,C2}|Crs], 0) -> % Get first range right
comp_crs(Crs, C2+1);
comp_crs([{C1,C2}|Crs], Last) ->
[{Last,C1-1}|comp_crs(Crs, C2+1)];
comp_crs([], Last) -> [{Last,maxchar}].
%% build_dfa(NFA, NfaFirstState) -> {DFA,DfaFirstState}.
%% Build a DFA from an NFA using "subset construction". The major
%% difference from the book is that we keep the marked and unmarked
%% DFA states in seperate lists. New DFA states are added to the
%% unmarked list and states are marked by moving them to the marked
%% list. We assume that the NFA accepting state numbers are in
%% ascending order for the rules and use ordsets to keep this order.
build_dfa(NFA, Nf) ->
D = #dfa_state{no=0,nfa=eclosure([Nf], NFA)},
{build_dfa([D], 1, [], NFA),0}.
%% build_dfa([UnMarked], NextState, [Marked], NFA) -> DFA.
%% Traverse the unmarked states. Temporarily add the current unmarked
%% state to the marked list before calculating translation, this is
%% to avoid adding too many duplicate states. Add it properly to the
%% marked list afterwards with correct translations.
build_dfa([U|Us0], N0, Ms, NFA) ->
{Ts,Us1,N1} = build_dfa(U#dfa_state.nfa, Us0, N0, [], [U|Ms], NFA),
M = U#dfa_state{trans=Ts,accept=accept(U#dfa_state.nfa, NFA)},
build_dfa(Us1, N1, [M|Ms], NFA);
build_dfa([], _, Ms, _) -> Ms.
%% build_dfa([NfaState], [Unmarked], NextState, [Transition], [Marked], NFA) ->
%% {Transitions,UnmarkedStates,NextState}.
%% Foreach NFA state set calculate the legal translations. N.B. must
%% search *BOTH* the unmarked and marked lists to check if DFA state
%% already exists. As the range of characters is potentially VERY
%% large we cannot explicitly test all characters. Instead we first
%% calculate the set of all disjoint character ranges which are
%% possible candidates to the set of NFA states. The transitions are
%% an orddict so we get the transition lists in ascending order.
build_dfa(Set, Us, N, Ts, Ms, NFA) ->
%% List of all transition sets.
Crs0 = [Cr || S <- Set,
{Crs,_St} <- (element(S, NFA))#nfa_state.edges,
Crs =/= epsilon, % Not an epsilon transition
Cr <- Crs ],
Crs1 = lists:usort(Crs0), % Must remove duplicates!
%% Build list of disjoint test ranges.
Test = disjoint_crs(Crs1),
%% io:fwrite("bd: ~p\n ~p\n ~p\n ~p\n", [Set,Crs0,Crs1,Test]),
build_dfa(Test, Set, Us, N, Ts, Ms, NFA).
%% disjoint_crs([CharRange]) -> [CharRange].
%% Take a sorted list of char ranges and make a sorted list of
%% disjoint char ranges. No new char range extends past an existing
%% char range.
disjoint_crs([{_C1,C2}=Cr1,{C3,_C4}=Cr2|Crs]) when C2 < C3 ->
%% C1 C2
%% C3 C4
[Cr1|disjoint_crs([Cr2|Crs])];
disjoint_crs([{C1,C2},{C3,C4}|Crs]) when C1 =:= C3 ->
%% C1 C2
%% C3 C4
[{C1,C2}|disjoint_crs(add_element({C2+1,C4}, Crs))];
disjoint_crs([{C1,C2},{C3,C4}|Crs]) when C1 < C3, C2 >= C3, C2 < C4 ->
%% C1 C2
%% C3 C4
[{C1,C3-1}|disjoint_crs(union([{C3,C2},{C2+1,C4}], Crs))];
disjoint_crs([{C1,C2},{C3,C4}|Crs]) when C1 < C3, C2 =:= C4 ->
%% C1 C2
%% C3 C4
[{C1,C3-1}|disjoint_crs(add_element({C3,C4}, Crs))];
disjoint_crs([{C1,C2},{C3,C4}|Crs]) when C1 < C3, C2 > C4 ->
%% C1 C2
%% C3 C4
[{C1,C3-1}|disjoint_crs(union([{C3,C4},{C4+1,C2}], Crs))];
disjoint_crs([Cr|Crs]) -> [Cr|disjoint_crs(Crs)];
disjoint_crs([]) -> [].
build_dfa([Cr|Crs], Set, Us, N, Ts, Ms, NFA) ->
case eclosure(move(Set, Cr, NFA), NFA) of
S when S =/= [] ->
case dfa_state_exist(S, Us, Ms) of
{yes,T} ->
build_dfa(Crs, Set, Us, N, store(Cr, T, Ts), Ms, NFA);
no ->
U = #dfa_state{no=N,nfa=S},
build_dfa(Crs, Set, [U|Us], N+1, store(Cr, N, Ts), Ms, NFA)
end;
[] ->
build_dfa(Crs, Set, Us, N, Ts, Ms, NFA)
end;
build_dfa([], _, Us, N, Ts, _, _) ->
{Ts,Us,N}.
%% dfa_state_exist(Set, Unmarked, Marked) -> {yes,State} | no.
dfa_state_exist(S, Us, Ms) ->
case lists:keyfind(S, #dfa_state.nfa, Us) of
#dfa_state{no=T} -> {yes,T};
false ->
case lists:keyfind(S, #dfa_state.nfa, Ms) of
#dfa_state{no=T} -> {yes,T};
false -> no
end
end.
%% eclosure([State], NFA) -> [State].
%% move([State], Char, NFA) -> [State].
%% These are straight out of the book. As eclosure uses ordsets then
%% the generated state sets are in ascending order.
eclosure(Sts, NFA) -> eclosure(Sts, NFA, []).
eclosure([St|Sts], NFA, Ec) ->
#nfa_state{edges=Es} = element(St, NFA),
eclosure([ N || {epsilon,N} <- Es,
not is_element(N, Ec) ] ++ Sts,
NFA, add_element(St, Ec));
eclosure([], _, Ec) -> Ec.
move(Sts, Cr, NFA) ->
%% io:fwrite("move1: ~p\n", [{Sts,Cr}]),
[ St || N <- Sts,
{Crs,St} <- (element(N, NFA))#nfa_state.edges,
Crs =/= epsilon, % Not an epsilon transition
in_crs(Cr, Crs) ].
in_crs({C1,C2}, [{C3,C4}|_Crs]) when C1 >= C3, C2 =< C4 -> true;
in_crs(Cr, [Cr|_Crs]) -> true; % Catch bos and eos.
in_crs(Cr, [_|Crs]) -> in_crs(Cr, Crs);
in_crs(_Cr, []) -> false.
%% accept([State], NFA) -> {accept,A} | noaccept.
%% Scan down the state list until we find an accepting state.
accept([St|Sts], NFA) ->
case element(St, NFA) of
#nfa_state{accept={accept,A}} -> {accept,A};
#nfa_state{accept=noaccept} -> accept(Sts, NFA)
end;
accept([], _) -> noaccept.
%% minimise_dfa(DFA, DfaFirst) -> {DFA,DfaFirst}.
%% Minimise the DFA by removing equivalent states. We consider a
%% state if both the transitions and the their accept state is the
%% same. First repeatedly run throught the DFA state list removing
%% equivalent states and updating remaining transitions with
%% remaining equivalent state numbers. When no more reductions are
%% possible then pack the remaining state numbers to get consecutive
%% states.
minimise_dfa(DFA0, Df0) ->
case min_dfa(DFA0) of
{DFA1,[]} -> % No reduction!
{DFA2,Rs} = pack_dfa(DFA1),
{min_update(DFA2, Rs),min_use(Df0, Rs)};
{DFA1,Rs} ->
minimise_dfa(min_update(DFA1, Rs), min_use(Df0, Rs))
end.
min_dfa(DFA) -> min_dfa(DFA, [], []).
min_dfa([D|DFA0], Rs0, MDFA) ->
{DFA1,Rs1} = min_delete(DFA0, D#dfa_state.trans, D#dfa_state.accept,
D#dfa_state.no, Rs0, []),
min_dfa(DFA1, Rs1, [D|MDFA]);
min_dfa([], Rs, MDFA) -> {MDFA,Rs}.
%% min_delete(States, Trans, Action, NewN, Rs, MiniDFA) -> {MiniDFA,Rs}.
%% Delete all states with same transactions and action. Return
%% rewrites and minimised DFA with no duplicate states.
min_delete([#dfa_state{no=N,trans=T,accept=A}|DFA], T, A, NewN, Rs, MDFA) ->
min_delete(DFA, T, A, NewN, [{N,NewN}|Rs], MDFA);
min_delete([D|DFA], T, A, NewN, Rs, MDFA) ->
min_delete(DFA, T, A, NewN, Rs, [D|MDFA]);
min_delete([], _, _, _, Rs, MDFA) -> {MDFA,Rs}.
min_update(DFA, Rs) ->
[ D#dfa_state{trans=min_update_trans(D#dfa_state.trans, Rs)} || D <- DFA ].
min_update_trans(Tr, Rs) ->
[ {C,min_use(S, Rs)} || {C,S} <- Tr ].
min_use(Old, [{Old,New}|_]) -> New;
min_use(Old, [_|Reds]) -> min_use(Old, Reds);
min_use(Old, []) -> Old.
pack_dfa(DFA) -> pack_dfa(DFA, 0, [], []).
pack_dfa([D|DFA], NewN, Rs, PDFA) ->
pack_dfa(DFA, NewN+1,
[{D#dfa_state.no,NewN}|Rs], [D#dfa_state{no=NewN}|PDFA]);
pack_dfa([], _, Rs, PDFA) -> {PDFA,Rs}.
%% The main output is the yystate function which is built from the
%% DFA. It has the spec:
%%
%% yystate() -> InitialState.
%% yystate(State, InChars, Line, CurrTokLen, AcceptAction, AcceptLen) ->
%% {Action, AcceptLength, RestChars, Line} | Accepting end state
%% {Action, AcceptLength, RestChars, Line, State} | Accepting state
%% {reject, AcceptLength, CurrTokLen, RestChars, Line, State} |
%% {Action, AcceptLength, CurrTokLen, RestChars, Line, State}.
%% The return CurrTokLen is always the current number of characters
%% scanned in the current token. The returns have the follwoing
%% meanings:
%% {Action, AcceptLength, RestChars, Line} -
%% The scanner has reached an accepting end-state, for example after
%% a regexp "abc". Action is the action number and AcceptLength is
%% the length of the matching token.
%%
%% {Action, AcceptLength, RestChars, Line, State} -
%% The scanner has reached an accepting transition state, for example
%% after c in regexp "abc(xyz)?", continuation depends on
%% RestChars. If RestChars == [] (no more current characters) then we
%% need to get more characters to see if it is an end-state,
%% otherwise (eof or chars) then we have not found continuing
%% characters and it is an end state.
%%
%% {reject, AcceptLength, CurrTokLen, RestChars, Line, State} -
%% {Action, AcceptLength, CurrTokLen, RestChars, Line, State} -
%% The scanner has reached a non-accepting transistion state. If
%% RestChars == [] we need to get more characters to continue.
%% Otherwise if 'reject' then no accepting state has been reached it
%% is an error. If we have an Action and AcceptLength then these are
%% the last accept state, use them and continue from there.
%% out_file(LeexState, DFA, DfaStart, [Action], Code) -> ok | error.
%% Generate an output .erl file from the include file, the DFA and
%% the code for the actions.
out_file(St0, DFA, DF, Actions, Code) ->
verbose_print(St0, "Writing file ~s, ", [St0#leex.efile]),
case open_inc_file(St0) of
{ok,Ifile} ->
try
case file:open(St0#leex.efile, [write]) of
{ok,Ofile} ->
set_encoding(St0, Ofile),
try
output_encoding_comment(Ofile, St0),
output_file_directive(Ofile, St0#leex.ifile, 0),
out_file(Ifile, Ofile, St0, DFA, DF, Actions,
Code, 1),
verbose_print(St0, "ok~n", []),
St0
after ok = file:close(Ofile)
end;
{error,Error} ->
verbose_print(St0, "error~n", []),
add_error({none,leex,{file_error,Error}}, St0)
end
after ok = file:close(Ifile)
end;
{{error,Error},Ifile} ->
add_error(Ifile, {none,leex,{file_error,Error}}, St0)
end.
open_inc_file(State) ->
Ifile = State#leex.ifile,
case file:open(Ifile, [read]) of
{ok,F} ->
_ = epp:set_encoding(F),
{ok,F};
Error -> {Error,Ifile}
end.
inc_file_name([]) ->
Incdir = filename:join(code:lib_dir(parsetools), "include"),
filename:join(Incdir, ?LEEXINC);
inc_file_name(Filename) ->
Filename.
%% out_file(IncFile, OutFile, State, DFA, DfaStart, Actions, Code, Line) -> ok
%% Copy the include file line by line substituting special lines with
%% generated code. We cheat by only looking at the first 5
%% characters.
out_file(Ifile, Ofile, St, DFA, DF, Actions, Code, L) ->
case io:get_line(Ifile, leex) of
eof -> output_file_directive(Ofile, St#leex.ifile, L);
{error, _} -> add_error(St#leex.ifile, {L, leex, cannot_parse}, St);
Line ->
case substr(Line, 1, 5) of
"##mod" -> out_module(Ofile, St);
"##cod" -> out_erlang_code(Ofile, St, Code, L);
"##dfa" -> out_dfa(Ofile, St, DFA, Code, DF, L);
"##act" -> out_actions(Ofile, St#leex.xfile, Actions);
_ -> io:put_chars(Ofile, Line)
end,
out_file(Ifile, Ofile, St, DFA, DF, Actions, Code, L+1)
end.
out_module(File, St) ->
io:fwrite(File, "-module(~w).\n", [St#leex.module]).
out_erlang_code(File, St, Code, L) ->
{CodeL,CodePos,_NCodeLines} = Code,
output_file_directive(File, St#leex.xfile, CodeL),
{ok,Xfile} = file:open(St#leex.xfile, [read]),
try
set_encoding(St, Xfile),
{ok,_} = file:position(Xfile, CodePos),
ok = file_copy(Xfile, File)
after
ok = file:close(Xfile)
end,
io:nl(File),
output_file_directive(File, St#leex.ifile, L).
file_copy(From, To) ->
case io:get_line(From, leex) of
eof -> ok;
Line when is_list(Line) ->
io:fwrite(To, "~ts", [Line]),
file_copy(From, To)
end.
out_dfa(File, St, DFA, Code, DF, L) ->
{_CodeL,_CodePos,NCodeLines} = Code,
%% Three file attributes before this one...
output_file_directive(File, St#leex.efile, L+(NCodeLines-1)+3),
io:fwrite(File, "yystate() -> ~w.~n~n", [DF]),
foreach(fun (S) -> out_trans(File, S) end, DFA),
io:fwrite(File, "yystate(S, Ics, Line, Tlen, Action, Alen) ->~n", []),
io:fwrite(File, " {Action,Alen,Tlen,Ics,Line,S}.~n", []).
out_trans(File, #dfa_state{no=N,trans=[],accept={accept,A}}) ->
%% Accepting end state, guaranteed done.
io:fwrite(File, "yystate(~w, Ics, Line, Tlen, _, _) ->~n", [N]),
io:fwrite(File, " {~w,Tlen,Ics,Line};~n", [A]);
out_trans(File, #dfa_state{no=N,trans=Tr,accept={accept,A}}) ->
%% Accepting state, but there maybe more.
foreach(fun (T) -> out_accept_tran(File, N, A, T) end, pack_trans(Tr)),
io:fwrite(File, "yystate(~w, Ics, Line, Tlen, _, _) ->~n", [N]),
io:fwrite(File, " {~w,Tlen,Ics,Line,~w};~n", [A,N]);
out_trans(File, #dfa_state{no=N,trans=Tr,accept=noaccept}) ->
%% Non-accepting transition state.
foreach(fun (T) -> out_noaccept_tran(File, N, T) end, pack_trans(Tr)),
io:fwrite(File, "yystate(~w, Ics, Line, Tlen, Action, Alen) ->~n", [N]),
io:fwrite(File, " {Action,Alen,Tlen,Ics,Line,~w};~n", [N]).
out_accept_tran(File, N, A, {{Cf,maxchar},S}) ->
out_accept_head_max(File, N, Cf),
out_accept_body(File, S, "Line", A);
out_accept_tran(File, N, A, {{Cf,Cl},S}) ->
out_accept_head_range(File, N, Cf, Cl),
out_accept_body(File, S, "Line", A);
out_accept_tran(File, N, A, {$\n,S}) ->
out_accept_head_1(File, N, $\n),
out_accept_body(File, S, "Line+1", A);
out_accept_tran(File, N, A, {C,S}) ->
out_accept_head_1(File, N, C),
out_accept_body(File, S, "Line", A).
out_accept_head_1(File, State, Char) ->
out_head_1(File, State, Char, "_", "_").
out_accept_head_max(File, State, Min) ->
out_head_max(File, State, Min, "_", "_").
out_accept_head_range(File, State, Min, Max) ->
out_head_range(File, State, Min, Max, "_", "_").
out_accept_body(File, Next, Line, Action) ->
out_body(File, Next, Line, io_lib:write(Action), "Tlen").
out_noaccept_tran(File, N, {{Cf,maxchar},S}) ->
out_noaccept_head_max(File, N, Cf),
out_noaccept_body(File, S, "Line");
out_noaccept_tran(File, N, {{Cf,Cl},S}) ->
out_noaccept_head_range(File, N, Cf, Cl),
out_noaccept_body(File, S, "Line");
out_noaccept_tran(File, N, {$\n,S}) ->
out_noaccept_head_1(File, N, $\n),
out_noaccept_body(File, S, "Line+1");
out_noaccept_tran(File, N, {C,S}) ->
out_noaccept_head_1(File, N, C),
out_noaccept_body(File, S, "Line").
out_noaccept_head_1(File, State, Char) ->
out_head_1(File, State, Char, "Action", "Alen").
out_noaccept_head_max(File, State, Min) ->
out_head_max(File, State, Min, "Action", "Alen").
out_noaccept_head_range(File, State, Min, Max) ->
out_head_range(File, State, Min, Max, "Action", "Alen").
out_noaccept_body(File, Next, Line) ->
out_body(File, Next, Line, "Action", "Alen").
out_head_1(File, State, Char, Action, Alen) ->
io:fwrite(File, "yystate(~w, [~w|Ics], Line, Tlen, ~s, ~s) ->\n",
[State,Char,Action,Alen]).
out_head_max(File, State, Min, Action, Alen) ->
io:fwrite(File, "yystate(~w, [C|Ics], Line, Tlen, ~s, ~s) when C >= ~w ->\n",
[State,Action,Alen,Min]).
out_head_range(File, State, Min, Max, Action, Alen) ->
io:fwrite(File, "yystate(~w, [C|Ics], Line, Tlen, ~s, ~s) when C >= ~w, C =< ~w ->\n",
[State,Action,Alen,Min,Max]).
out_body(File, Next, Line, Action, Alen) ->
io:fwrite(File, " yystate(~w, Ics, ~s, Tlen+1, ~s, ~s);\n",
[Next,Line,Action,Alen]).
%% pack_trans([{Crange,State}]) -> [{Crange,State}] when
%% Crange = {Char,Char} | Char.
%% Pack the translation table into something more suitable for
%% generating code. We KNOW how the pattern matching compiler works
%% so solitary characters are stored before ranges. We do this by
%% prepending singletons to the front of the packed transitions and
%% appending ranges to the back. This preserves the smallest to
%% largest order of ranges. Newline characters, $\n, are always
%% extracted and handled as singeltons.
pack_trans(Trs) -> pack_trans(Trs, []).
%% pack_trans(Trs) ->
%% Trs1 = pack_trans(Trs, []),
%% io:fwrite("tr:~p\n=> ~p\n", [Trs,Trs1]),
%% Trs1.
pack_trans([{{C,C},S}|Trs], Pt) -> % Singletons to the head
pack_trans(Trs, [{C,S}|Pt]);
%% Special detection and handling of $\n.
pack_trans([{{Cf,$\n},S}|Trs], Pt) ->
pack_trans([{{Cf,$\n-1},S}|Trs], [{$\n,S}|Pt]);
pack_trans([{{$\n,Cl},S}|Trs], Pt) ->
pack_trans([{{$\n+1,Cl},S}|Trs], [{$\n,S}|Pt]);
pack_trans([{{Cf,Cl},S}|Trs], Pt) when Cf < $\n, Cl > $\n ->
pack_trans([{{Cf,$\n-1},S},{{$\n+1,Cl},S}|Trs], [{$\n,S}|Pt]);
%% Small ranges become singletons.
pack_trans([{{Cf,Cl},S}|Trs], Pt) when Cl =:= Cf + 1 ->
pack_trans(Trs, [{Cf,S},{Cl,S}|Pt]);
pack_trans([Tr|Trs], Pt) -> % The default uninteresting case
pack_trans(Trs, Pt ++ [Tr]);
pack_trans([], Pt) -> Pt.
%% out_actions(File, XrlFile, ActionList) -> ok.
%% Write out the action table.
out_actions(File, XrlFile, As) ->
As1 = prep_out_actions(As),
foreach(fun (A) -> out_action(File, A) end, As1),
io:fwrite(File, "yyaction(_, _, _, _) -> error.~n", []),
foreach(fun (A) -> out_action_code(File, XrlFile, A) end, As1).
prep_out_actions(As) ->
map(fun ({A,empty_action}) ->
{A,empty_action};
({A,Code,TokenChars,TokenLen,TokenLine}) ->
Vs = [{TokenChars,"TokenChars"},
{TokenLen,"TokenLen"},
{TokenLine,"TokenLine"},
{TokenChars,"YYtcs"},
{TokenLen or TokenChars,"TokenLen"}],
Vars = [if F -> S; true -> "_" end || {F,S} <- Vs],
Name = list_to_atom(lists:concat([yyaction_,A])),
[Chars,Len,Line,_,_] = Vars,
Args = [V || V <- [Chars,Len,Line], V =/= "_"],
ArgsChars = string:join(Args, ", "),
{A,Code,Vars,Name,Args,ArgsChars}
end, As).
out_action(File, {A,empty_action}) ->
io:fwrite(File, "yyaction(~w, _, _, _) -> skip_token;~n", [A]);
out_action(File, {A,_Code,Vars,Name,_Args,ArgsChars}) ->
[_,_,Line,Tcs,Len] = Vars,
io:fwrite(File, "yyaction(~w, ~s, ~s, ~s) ->~n", [A,Len,Tcs,Line]),
if
Tcs =/= "_" ->
io:fwrite(File, " TokenChars = yypre(YYtcs, TokenLen),~n", []);
true -> ok
end,
io:fwrite(File, " ~s(~s);~n", [Name, ArgsChars]).
out_action_code(_File, _XrlFile, {_A,empty_action}) ->
ok;
out_action_code(File, XrlFile, {_A,Code,_Vars,Name,Args,ArgsChars}) ->
%% Should set the file to the .erl file, but instead assumes that
%% ?LEEXINC is syntactically correct.
io:fwrite(File, "\n-compile({inline,~w/~w}).\n", [Name, length(Args)]),
{line, L} = erl_scan:token_info(hd(Code), line),
output_file_directive(File, XrlFile, L-2),
io:fwrite(File, "~s(~s) ->~n", [Name, ArgsChars]),
io:fwrite(File, " ~s\n", [pp_tokens(Code, L)]).
%% pp_tokens(Tokens, Line) -> [char()].
%% Prints the tokens keeping the line breaks of the original code.
pp_tokens(Tokens, Line0) -> pp_tokens(Tokens, Line0, none).
pp_tokens([], _Line0, _) -> [];
pp_tokens([T | Ts], Line0, Prev) ->
{line, Line} = erl_scan:token_info(T, line),
[pp_sep(Line, Line0, Prev, T), pp_symbol(T) | pp_tokens(Ts, Line, T)].
pp_symbol({var,_,Var}) -> atom_to_list(Var);
pp_symbol({_,_,Symbol}) -> io_lib:fwrite("~p", [Symbol]);
pp_symbol({dot, _}) -> ".";
pp_symbol({Symbol, _}) -> atom_to_list(Symbol).
pp_sep(Line, Line0, Prev, T) when Line > Line0 ->
["\n " | pp_sep(Line - 1, Line0, Prev, T)];
pp_sep(_, _, {'.',_}, _) -> ""; % No space after '.' (not a dot)
pp_sep(_, _, {'#',_}, _) -> ""; % No space after '#'
pp_sep(_, _, {'(',_}, _) -> ""; % No space after '('
pp_sep(_, _, {'[',_}, _) -> ""; % No space after '['
pp_sep(_, _, _, {'.',_}) -> ""; % No space before '.'
pp_sep(_, _, _, {'#',_}) -> ""; % No space before '#'
pp_sep(_, _, _, {',',_}) -> ""; % No space before ','
pp_sep(_, _, _, {')',_}) -> ""; % No space before ')'
pp_sep(_, _, _, _) -> " ".
%% out_dfa_graph(LeexState, DFA, DfaStart) -> ok | error.
%% Writes the DFA to a .dot file in DOT-format which can be viewed
%% with Graphviz.
out_dfa_graph(St, DFA, DF) ->
verbose_print(St, "Writing DFA to file ~s, ", [St#leex.gfile]),
case file:open(St#leex.gfile, [write]) of
{ok,Gfile} ->
try
io:fwrite(Gfile, "digraph DFA {~n", []),
out_dfa_states(Gfile, DFA, DF),
out_dfa_edges(Gfile, DFA),
io:fwrite(Gfile, "}~n", []),
verbose_print(St, "ok~n", []),
St
after ok = file:close(Gfile)
end;
{error,Error} ->
verbose_print(St, "error~n", []),
add_error({none,leex,{file_error,Error}}, St)
end.
out_dfa_states(File, DFA, DF) ->
foreach(fun (S) -> out_dfa_state(File, DF, S) end, DFA),
io:fwrite(File, "~n", []).
out_dfa_state(File, DF, #dfa_state{no=DF, accept={accept,_}}) ->
io:fwrite(File, " ~b [shape=doublecircle color=green];~n", [DF]);
out_dfa_state(File, DF, #dfa_state{no=DF, accept=noaccept}) ->
io:fwrite(File, " ~b [shape=circle color=green];~n", [DF]);
out_dfa_state(File, _, #dfa_state{no=S, accept={accept,_}}) ->
io:fwrite(File, " ~b [shape=doublecircle];~n", [S]);
out_dfa_state(File, _, #dfa_state{no=S, accept=noaccept}) ->
io:fwrite(File, " ~b [shape=circle];~n", [S]).
out_dfa_edges(File, DFA) ->
foreach(fun (#dfa_state{no=S,trans=Trans}) ->
Pt = pack_trans(Trans),
Tdict = foldl(fun ({Cr,T}, D) ->
orddict:append(T, Cr, D)
end, orddict:new(), Pt),
foreach(fun (T) ->
Crs = orddict:fetch(T, Tdict),
Edgelab = dfa_edgelabel(Crs),
io:fwrite(File, " ~b -> ~b [label=\"~s\"];~n",
[S,T,Edgelab])
end, sort(orddict:fetch_keys(Tdict)))
end, DFA).
dfa_edgelabel([C]) when is_integer(C) -> quote(C);
dfa_edgelabel(Cranges) ->
%% io:fwrite("el: ~p\n", [Cranges]),
"[" ++ map(fun ({A,B}) -> [quote(A), "-", quote(B)];
(C) -> [quote(C)]
end, Cranges) ++ "]".
set_encoding(#leex{encoding = none}, File) ->
ok = io:setopts(File, [{encoding, epp:default_encoding()}]);
set_encoding(#leex{encoding = E}, File) ->
ok = io:setopts(File, [{encoding, E}]).
output_encoding_comment(_File, #leex{encoding = none}) ->
ok;
output_encoding_comment(File, #leex{encoding = Encoding}) ->
io:fwrite(File, <<"%% ~s\n">>, [epp:encoding_to_string(Encoding)]).
output_file_directive(File, Filename, Line) ->
io:fwrite(File, <<"-file(~s, ~w).\n">>,
[format_filename(Filename), Line]).
format_filename(Filename) ->
io_lib:write_string(filename:flatten(Filename)).
quote($^) -> "\\^";
quote($.) -> "\\.";
quote($$) -> "\\$";
quote($-) -> "\\-";
quote($[) -> "\\[";
quote($]) -> "\\]";
quote($\s) -> "\\\\s";
quote($\") -> "\\\"";
quote($\b) -> "\\\\b";
quote($\f) -> "\\\\f";
quote($\n) -> "\\\\n";
quote($\r) -> "\\\\r";
quote($\t) -> "\\\\t";
quote($\e) -> "\\\\e";
quote($\v) -> "\\\\v";
quote($\d) -> "\\\\d";
quote($\\) -> "\\\\";
quote(C) when is_integer(C) ->
%% Must remove the $ and get the \'s right.
case io_lib:write_char(C) of
[$$,$\\|Cs] -> "\\\\" ++ Cs;
[$$|Cs] -> Cs
end;
quote(maxchar) ->
"MAXCHAR".
