%%%----------------------------------------------------------------------
%%% File : eed.erl
%%% Author : Bjorn Gustavsson <bjorn@strider>
%%% Purpose : Unix `ed' look-alike.
%%% Created : 24 Aug 1997 by Bjorn Gustavsson <bjorn@strider>
%%%----------------------------------------------------------------------
-module(eed).
-author('bjorn@strider').
-export([edit/0, edit/1, file/1, cmd_line/1]).
-compile({no_auto_import,[error/1]}).
-record(state, {dot = 0, % Line number of dot.
upto_dot = [], % Lines up to dot (reversed).
after_dot = [], % Lines after dot.
lines = 0, % Total number of lines.
print=false, % Print after command.
filename=[], % Current file.
pattern, % Current pattern.
in_global=false, % True if executing global command.
input=[], % Global input stream.
undo, % Last undo state.
marks=[], % List of marks.
modified=false, % Buffer is modified.
opts=[{prompt, ''}], % Options.
last_error, % The last error encountered.
input_fd % Input file descriptor.
}).
-record(line, {contents, % Contents of line.
mark=false % Marked (for global prefix).
}).
cmd_line([Script]) ->
file(Script),
halt().
file(Script) ->
case file:open(Script, [read]) of
{ok,Fd} ->
loop(#state{input_fd=Fd}),
ok;
{error,E} ->
{error,E}
end.
edit() ->
loop(#state{input_fd=group_leader()}).
edit(Name) ->
loop(command([$e|Name], #state{input_fd=group_leader()})).
loop(St0) ->
{ok, St1, Cmd} = get_line(St0),
case catch command(lib:nonl(Cmd), St1) of
{'EXIT', Reason} ->
%% XXX Should clear outstanding global command here.
loop(print_error({'EXIT', Reason}, St1));
quit ->
ok;
{error, Reason} ->
loop(print_error(Reason, St1));
St2 when is_record(St2, state) ->
loop(St2)
end.
command(Cmd, St) ->
case parse_command(Cmd, St) of
quit ->
quit;
St1 when is_function(St1#state.print) ->
if
St1#state.dot /= 0 ->
print_current(St1);
true ->
ok
end,
St1#state{print=false};
St1 when is_record(St1, state) ->
St1
end.
get_line(St) ->
Opts = St#state.opts,
{value, {prompt, Prompt}} = lists:keysearch(prompt, 1, Opts),
get_line(Prompt, St).
get_line(Prompt, St) when St#state.input == [] ->
Line = get_line1(St#state.input_fd, Prompt, []),
{ok, St, Line};
get_line(_, St) ->
get_input(St#state.input, St, []).
get_input([eof], St, []) ->
{ok, St, eof};
get_input([eof], St, Result) ->
{ok, St#state{input=[eof]}, lists:reverse(Result)};
get_input([$\n|Rest], St, Result) ->
{ok, St#state{input=Rest}, lists:reverse(Result)};
get_input([C|Rest], St, Result) ->
get_input(Rest, St, [C|Result]).
get_line1(Io, Prompt, Result) ->
get_line2(Io, io:get_line(Io, Prompt), Result).
get_line2(_Io, eof, []) ->
eof;
get_line2(_Io, eof, Result) ->
lists:reverse(Result);
get_line2(Io, [$\\, $\n], Result) ->
get_line1(Io, '', [$\n|Result]);
get_line2(_Io, [$\n], Result) ->
lists:reverse(Result, [$\n]);
get_line2(Io, [C|Rest], Result) ->
get_line2(Io, Rest, [C|Result]).
print_error(Reason, St0) ->
St1 = St0#state{last_error=Reason},
io:put_chars("?\n"),
case lists:member(help_always, St1#state.opts) of
true ->
help_command([], [], St1),
St1;
false ->
St1
end.
format_error(bad_command) -> "unknown command";
format_error(bad_filename) -> "illegal or missing filename";
format_error(bad_file) -> "cannot open input file";
format_error(bad_linenum) -> "line out of range";
format_error(bad_delimiter) -> "illegal or missing delimiter";
format_error(bad_undo) -> "nothing to undo";
format_error(bad_mark) -> "mark not lower case ascii";
format_error(bad_pattern) -> "invalid regular expression";
format_error(buffer_modified) -> "warning: expecting `w'";
format_error(nested_globals) -> "multiple globals not allowed";
format_error(nomatch) -> "search string not found";
format_error(missing_space) -> "no space after command";
format_error(garbage_after_command) -> "illegal suffix";
format_error(not_implemented) -> "not implemented yet";
format_error({'EXIT', {Code, {Mod, Func, Args}}}) ->
lists:flatten(io_lib:format("aborted due to bug (~p)",
[{Code, {Mod, Func, length(Args)}}]));
format_error(A) -> atom_to_list(A).
%%% Parsing commands.
parse_command(Cmd, St) ->
parse_command(Cmd, St, []).
parse_command(Cmd, State, Nums) ->
case get_one(Cmd, State) of
{ok, Num, Rest, NewState} ->
parse_next_address(Rest, NewState, [Num|Nums]);
false ->
parse_command1(Cmd, State, Nums)
end.
parse_next_address([$,|Rest], State, Nums) ->
parse_command(Rest, State, Nums);
parse_next_address([$;|Rest], State, [Num|Nums]) ->
parse_command(Rest, move_to(Num, State), [Num|Nums]);
parse_next_address(Rest, State, Nums) ->
parse_command1(Rest, State, Nums).
parse_command1([Letter|Rest], State, Nums) ->
Cont = fun(Fun, NumLines, Def) ->
execute_command(Fun, NumLines, Def, State, Nums, Rest) end,
parse_cmd_char(Letter, Cont);
parse_command1([], State, Nums) ->
execute_command(fun print_command/3, 1, next, State, Nums, []).
get_one(Cmd, St) ->
case get_address(Cmd, St) of
{ok, Addr, Cmd1, St1} ->
get_one1(Cmd1, Addr, St1);
false ->
get_one1(Cmd, false, St)
end.
get_one1([D|Rest], false, St) when $0 =< D, D =< $9 ->
get_one2(get_number([D|Rest]), 1, 0, St);
get_one1([D|Rest], Sum, St) when $0 =< D, D =< $9 ->
get_one2(get_number([D|Rest]), 1, Sum, St);
get_one1([$+, D|Rest], Sum, St) when $0 =< D, D =< $9 ->
get_one2(get_number([D|Rest]), 1, Sum, St);
get_one1([$-, D|Rest], Sum, St) when $0 =< D, D =< $9 ->
get_one2(get_number([D|Rest]), -1, Sum, St);
get_one1([$+|Rest], Sum, St) ->
get_one2({ok, 1, Rest}, 1, Sum, St);
get_one1([$-|Rest], Sum, St) ->
get_one2({ok, 1, Rest}, -1, Sum, St);
get_one1(_Cmd, false, _St) ->
false;
get_one1(Cmd, Sum, St) ->
{ok, Sum, Cmd, St}.
get_one2({ok, Number, Rest}, Mul, false, St) ->
get_one1(Rest, St#state.dot+Mul*Number, St);
get_one2({ok, Number, Rest}, Mul, Sum, St) ->
get_one1(Rest, Sum+Mul*Number, St).
get_number(Cmd) ->
get_number(Cmd, 0).
get_number([D|Rest], Result) when $0 =< D, D =< $9 ->
get_number(Rest, Result*10+D-$0);
get_number(Rest, Result) ->
{ok, Result, Rest}.
get_address([$.|Rest], State) ->
{ok, State#state.dot, Rest, State};
get_address([$$|Rest], State) ->
{ok, State#state.lines, Rest, State};
get_address([$', Mark|Rest], St) when $a =< Mark, Mark =< $z ->
case lists:keysearch(Mark, 2, St#state.marks) of
{value, {Line, Mark}} ->
{ok, Line, Rest, St};
false ->
{ok, 0, Rest, St}
end;
get_address([$'|_Rest], _State) ->
error(bad_mark);
get_address([$/|Rest], State) ->
scan_forward($/, Rest, State);
get_address([$?|_Rest], _State) ->
error(not_implemented);
get_address(_Cmd, _St) ->
false.
scan_forward(End, Patt0, State) ->
{ok, Rest, NewState} = get_pattern(End, Patt0, State),
Dot = NewState#state.dot,
After = NewState#state.after_dot,
scan_forward1(Dot+1, After, NewState, Rest).
scan_forward1(Linenum, [Line|Rest], State, RestCmd) ->
case re:run(Line#line.contents, State#state.pattern, [{capture, none}]) of
match ->
{ok, Linenum, RestCmd, State};
nomatch ->
scan_forward1(Linenum+1, Rest, State, RestCmd)
end;
scan_forward1(_, [], State, RestCmd) ->
Dot = State#state.dot,
Upto = State#state.upto_dot,
case scan_forward2(Dot, Upto, State, RestCmd) of
false ->
error(bad_linenum);
Other ->
Other
end.
scan_forward2(0, [], _State, _RestCmd) ->
false;
scan_forward2(Linenum, [Line|Rest], State, RestCmd) ->
case scan_forward2(Linenum-1, Rest, State, RestCmd) of
false ->
case re:run(Line#line.contents, State#state.pattern,
[{capture, none}]) of
match ->
{ok, Linenum, RestCmd, State};
nomatch ->
false
end;
Other ->
Other
end.
parse_cmd_char($S, Cont) -> Cont(fun quest_command/3, 0, none);
parse_cmd_char($T, Cont) -> Cont(fun time_command/3, 0, none);
parse_cmd_char($=, Cont) -> Cont(fun print_linenum/3, 1, last);
parse_cmd_char($a, Cont) -> Cont(fun append_command/3, 1, dot);
parse_cmd_char($c, Cont) -> Cont(fun change_command/3, 2, dot);
parse_cmd_char($d, Cont) -> Cont(fun delete_command/3, 2, dot);
parse_cmd_char($e, Cont) -> Cont(fun enter_command/3, 0, none);
parse_cmd_char($E, Cont) -> Cont(fun enter_always_command/3, 0, none);
parse_cmd_char($f, Cont) -> Cont(fun file_command/3, 0, none);
parse_cmd_char($g, Cont) -> Cont(fun global_command/3, 2, all);
parse_cmd_char($h, Cont) -> Cont(fun help_command/3, 0, none);
parse_cmd_char($H, Cont) -> Cont(fun help_always_command/3, 0, none);
parse_cmd_char($i, Cont) -> Cont(fun insert_command/3, 1, dot);
parse_cmd_char($k, Cont) -> Cont(fun mark_command/3, 1, dot);
parse_cmd_char($l, Cont) -> Cont(fun list_command/3, 2, dot);
parse_cmd_char($m, Cont) -> Cont(fun move_command/3, 2, dot);
parse_cmd_char($n, Cont) -> Cont(fun number_command/3, 2, dot);
parse_cmd_char($p, Cont) -> Cont(fun print_command/3, 2, dot);
parse_cmd_char($P, Cont) -> Cont(fun prompt_command/3, 0, none);
parse_cmd_char($q, Cont) -> Cont(fun quit_command/3, 0, none);
parse_cmd_char($Q, Cont) -> Cont(fun quit_always_command/3, 0, none);
parse_cmd_char($r, Cont) -> Cont(fun read_command/3, 1, last);
parse_cmd_char($s, Cont) -> Cont(fun subst_command/3, 2, dot);
parse_cmd_char($t, Cont) -> Cont(fun transpose_command/3, 2, dot);
parse_cmd_char($u, Cont) -> Cont(fun undo_command/3, 0, none);
parse_cmd_char($v, Cont) -> Cont(fun vglobal_command/3, 2, all);
parse_cmd_char($w, Cont) -> Cont(fun write_command/3, 2, all);
parse_cmd_char(_, _Cont) -> error(bad_command).
execute_command(Fun, NumLines, Def, State, Nums, Rest) ->
Lines = check_lines(NumLines, Def, Nums, State),
Fun(Rest, Lines, State).
check_lines(0, _, [], _State) ->
[];
check_lines(1, dot, [], #state{dot=Dot}) ->
[Dot];
check_lines(1, next, [], State) when State#state.dot < State#state.lines ->
[State#state.dot+1];
check_lines(1, last, [], State) ->
[State#state.lines];
check_lines(1, _, [Num|_], State) when 0 =< Num, Num =< State#state.lines ->
[Num];
check_lines(2, dot, [], #state{dot=Dot}) ->
[Dot, Dot];
check_lines(2, all, [], #state{lines=Lines}) ->
[1, Lines];
check_lines(2, _, [Num], State) when 0 =< Num, Num =< State#state.lines ->
[Num, Num];
check_lines(2, _, [Num2, Num1|_], State)
when 0 =< Num1, Num1 =< Num2, Num2 =< State#state.lines ->
[Num1, Num2];
check_lines(_, _, _, _) ->
error(bad_linenum).
%%% Executing commands.
%% ($)= - print line number
print_linenum(Rest, [Line], State) ->
NewState = check_trailing_p(Rest, State),
io:format("~w\n", [Line]),
NewState.
%% ? - print state (for debugging)
quest_command([], [], State) ->
io:format("~p\n", [State]),
State.
%% Tcmd - time command
time_command(Cmd, [], St) ->
Fun = fun parse_command/2,
erlang:garbage_collect(),
{Elapsed, Val} = timer:tc(erlang, apply, [Fun, [Cmd, St]]),
io:format("Time used: ~p s~n", [Elapsed/1000000.0]),
case Val of
{error, Reason} ->
throw({error, Reason});
Other ->
Other
end.
%% (.)a - append text
append_command(Rest, [Line], St0) ->
St1 = save_for_undo(St0),
append(move_to(Line, check_trailing_p(Rest, St1))).
append(St0) ->
{ok, St1, Line0} = get_line('', St0),
case Line0 of
eof ->
St1;
".\n" ->
St1;
Line ->
append(insert_line(Line, St1))
end.
%% (.,.)c
change_command(Rest, Lines, St0) ->
St1 = delete_command(Rest, Lines, St0),
St2 = append_command([], [St1#state.dot-1], St1),
save_for_undo(St2, St0).
%% (.,.)d - delete lines
delete_command(_Rest, [0, _Last], _St) ->
error(bad_linenum);
delete_command(Rest, [First, Last], St0) ->
St1 = check_trailing_p(Rest, save_for_undo(St0)),
delete(Last-First+1, move_to(Last, St1)).
delete(0, St) when St#state.dot == St#state.lines ->
St;
delete(0, St) ->
next_line(St);
delete(Left, St0) ->
St1 = delete_current_line(St0),
delete(Left-1, St1).
%% e file - replace buffer with new file
enter_command(_Name, [], St) when St#state.modified == true ->
error(buffer_modified);
enter_command(Name, [], St0) ->
enter_always_command(Name, [], St0).
%% E file - replace buffer with new file
enter_always_command(Name, [], St0) ->
St1 = read_command(Name, [0], #state{filename=St0#state.filename,
opts=St0#state.opts}),
St1#state{modified=false}.
%% f file - print filename; set filename
file_command([], [], St) ->
io:format("~s~n", [St#state.filename]),
St;
file_command([$_|Name0], [], St) ->
Name = skip_blanks(Name0),
file_command([], [], St#state{filename=Name});
file_command(_, _, _) ->
error(missing_space).
%% (1,$)g/RE/commands - execute commands on all matching lines.
%% (1,$)v/RE/commands - execute commands on all non-matching lines.
global_command(Cmd, Lines, St) ->
check_global0(true, Cmd, Lines, St).
vglobal_command(Cmd, Lines, St) ->
check_global0(false, Cmd, Lines, St).
check_global0(_, _, _, St) when St#state.in_global == true ->
error(nested_globals);
check_global0(Sense, [Sep|Pattern], Lines, St0) ->
{ok, Cmd, St1} = get_pattern(Sep, Pattern, St0),
St2 = mark(Sense, Lines, St1),
do_global_command(Cmd, St2#state{in_global=true}, 0).
mark(Sense, [First, Last], St0) ->
St1 = move_to(Last, St0),
mark1(Sense, First-1, St1).
mark1(_Sense, First, St) when St#state.dot == First ->
St;
mark1(Sense, First, St) ->
[Line|Prev] = St#state.upto_dot,
NewLine = case match(St) of
true -> Line#line{mark=Sense};
false -> Line#line{mark=not(Sense)}
end,
mark1(Sense, First, prev_line(St#state{upto_dot=[NewLine|Prev]})).
do_global_command(Cmd, St0, Matches) ->
case find_mark(St0) of
{ok, St1} ->
St2 = St1#state{input=Cmd++[eof]},
{ok, St3, Cmd1} = get_line(St2),
St4 = command(Cmd1, St3),
%% XXX There might be several commands.
do_global_command(Cmd, St4, Matches+1);
false when Matches == 0 ->
error(nomatch);
false ->
St0#state{in_global=false, input=[]}
end.
find_mark(State) ->
find_mark(State#state.lines, State).
find_mark(0, _State) ->
false;
find_mark(Limit, State) when State#state.dot == 0 ->
find_mark(Limit, next_line(State));
find_mark(Limit, State) ->
case State#state.upto_dot of
[Line|Prev] when Line#line.mark == true ->
NewLine = Line#line{mark=false},
{ok, State#state{upto_dot=[NewLine|Prev]}};
_Other ->
find_mark(Limit-1, wrap_next_line(State))
end.
%% h - print info about last error
help_command([], [], St) ->
case St#state.last_error of
undefined ->
St;
Reason ->
io:put_chars(format_error(Reason)),
io:nl(),
St
end;
help_command(_, _, _) ->
error(garbage_after_command).
%% H - toggle automatic help mode on/off
help_always_command([], [], St) ->
Opts = St#state.opts,
case lists:member(help_always, Opts) of
true ->
St#state{opts=Opts--[help_always]};
false ->
help_command([], [], St),
St#state{opts=[help_always|Opts]}
end.
%% (.)i - insert text
insert_command(_Rest, [0], _State) ->
error(bad_linenum);
insert_command(Rest, [Line], State) ->
append_command(Rest, [Line-1], State).
%% (.)kx - mark line
mark_command(_, [0], _St) ->
error(bad_linenum);
mark_command([Mark|_Rest], [_Line], _St) when $a =< Mark, Mark =< $z ->
error(not_implemented);
mark_command(_, _, _) ->
error(bad_mark).
%% (.,.)l - list lines
list_command(Rest, Lines, St) ->
print([$l|Rest], Lines, St).
%% (.,.)m - move lines
move_command(_Cmd, [_First, _Last], _St) ->
error(not_implemented).
%% (.,.)t - copy lines
transpose_command(_Cmd, [_First, _Last], _St) ->
error(not_implemented).
%% (.,.)n - print lines with line numbers
number_command(Rest, Lines, St) ->
print([$n|Rest], Lines, St).
%% (.,.)p - print lines
print_command(Rest, Lines, St) ->
print([$p|Rest], Lines, St).
%% P - toggle prompt
prompt_command([], [], St) ->
Opts = St#state.opts,
case lists:keysearch(prompt, 1, Opts) of
{value, {prompt, ''}} ->
St#state{opts=[{prompt, '*'}|Opts]};
{value, Value} ->
St#state{opts=[{prompt, ''} | Opts--[Value]]}
end;
prompt_command(_, _, _) ->
error(garbage_after_command).
%% q - quit editor
quit_command([], [], _) ->
quit;
quit_command(_, _, _) ->
error(garbage_after_command).
%% Q - quit editor
quit_always_command([], [], _) ->
quit;
quit_always_command(_, _, _) ->
error(garbage_after_command).
%% ($)r file - read file
read_command([], _, St) when St#state.filename == [] ->
error(bad_filename);
read_command([], [After], St) ->
read(After, St#state.filename, St);
read_command([$ |Name0], [After], St) when St#state.filename == [] ->
Name = skip_blanks(Name0),
read(After, Name, St#state{filename=Name});
read_command([$ |Name0], [After], St) ->
Name = skip_blanks(Name0),
read(After, Name, St);
read_command(_, _, _) ->
error(missing_space).
read(After, Name, St0) ->
case file:read_file(Name) of
{ok, Bin} ->
Chars = size(Bin),
St1 = move_to(After, St0),
St2 = insert_line(binary_to_list(Bin), St1),
io:format("~w~n", [Chars]),
St2;
{error, _} ->
error(bad_file)
end.
%% s/pattern/replacement/gp
subst_command(_, [0, _], _) ->
error(bad_linenum);
subst_command([$ |_Cmd0], [_First, _Last], _St0) ->
error(bad_delimiter);
subst_command([$\n|_Cmd0], [_First, _Last], _St0) ->
error(bad_delimiter);
subst_command([Sep|Cmd0], [First, Last], St0) ->
St1 = save_for_undo(St0),
{ok, Cmd1, St2} = get_pattern(Sep, Cmd0, St1),
{ok, Replacement, Cmd2} = get_replacement(Sep, Cmd1),
{ok, Opts, Cmd3} = subst_check_gflag(Cmd2),
St3 = check_trailing_p(Cmd3, St2),
subst_command(Last-First+1, Opts, Replacement,
move_to(First-1, St3), nomatch);
subst_command([], _, _) ->
error(bad_delimiter).
subst_command(0, _, _, _, nomatch) ->
error(nomatch);
subst_command(0, _, _, _, StLast) when is_record(StLast, state) ->
StLast;
subst_command(Left, Opts, Repl, St0, LastMatch) ->
St1 = next_line(St0),
[Line|_] = St1#state.upto_dot,
Contents = Line#line.contents,
case re:replace(Contents, St1#state.pattern, Repl, Opts) of
Contents ->
subst_command(Left-1, Opts, Repl, St1, LastMatch);
NewContents ->
%% XXX This doesn't work with marks.
St2 = delete_current_line(St1),
St3 = insert_line(NewContents, St2),
subst_command(Left-1, Opts, Repl, St3, St3)
end.
subst_check_gflag([$g|Cmd]) -> {ok, [global,{return,list}], Cmd};
subst_check_gflag(Cmd) -> {ok, [{return,list}], Cmd}.
%% u - undo
undo_command([], [], St) when St#state.undo == undefined ->
error(bad_undo);
undo_command([], [], #state{undo=Undo}) ->
Undo;
undo_command(_, _, _) ->
error(garbage_after_command).
%% (1,$)w - write buffer to file
write_command(_Cmd, [_First, _Last], _St) ->
error(not_implemented).
%%% Primitive buffer operations.
print_current(St) ->
[Line|_] = St#state.upto_dot,
Printer = St#state.print,
Printer(Line#line.contents, St).
delete_current_line(St) when St#state.dot == 0 ->
error(bad_linenum);
delete_current_line(St) ->
Lines = St#state.lines,
[_|Prev] = St#state.upto_dot,
St#state{dot=St#state.dot-1, upto_dot=Prev, lines=Lines-1, modified=true}.
insert_line(Line, State) ->
insert_line1(Line, State, []).
insert_line1([$\n|Rest], State, Result) ->
NewState = insert_single_line(lists:reverse(Result, [$\n]), State),
insert_line1(Rest, NewState, []);
insert_line1([C|Rest], State, Result) ->
insert_line1(Rest, State, [C|Result]);
insert_line1([], State, []) ->
State;
insert_line1([], State, Result) ->
insert_single_line(lists:reverse(Result, [$\n]), State).
insert_single_line(Line0, State) ->
Line = #line{contents=Line0},
Dot = State#state.dot,
Before = State#state.upto_dot,
Lines = State#state.lines,
%% XXX Avoid updating the record every time.
State#state{dot=Dot+1, upto_dot=[Line|Before], lines=Lines+1, modified=true}.
move_to(Line, State) when Line < State#state.dot ->
move_to(Line, prev_line(State));
move_to(Line, State) when State#state.dot < Line ->
move_to(Line, next_line(State));
move_to(Line, State) when Line == State#state.dot ->
State.
prev_line(State) ->
Dot = State#state.dot,
Before = State#state.upto_dot,
After = State#state.after_dot,
State#state{dot=Dot-1, upto_dot=tl(Before), after_dot=[hd(Before)|After]}.
next_line(State) ->
Dot = State#state.dot,
Before = State#state.upto_dot,
After = State#state.after_dot,
State#state{dot=Dot+1, upto_dot=[hd(After)|Before], after_dot=tl(After)}.
wrap_next_line(State) when State#state.dot == State#state.lines ->
move_to(1, State);
wrap_next_line(State) ->
next_line(State).
%%% Utilities.
get_pattern(End, Cmd, State) ->
get_pattern(End, Cmd, State, []).
get_pattern(End, [End|Rest], State, []) when State#state.pattern /= undefined ->
{ok, Rest, State};
get_pattern(End, [End|Rest], State, Result) ->
case re:compile(lists:reverse(Result)) of
{error, _} ->
error(bad_pattern);
{ok, Re} ->
{ok, Rest, State#state{pattern=Re}}
end;
get_pattern(End, [C|Rest], State, Result) ->
get_pattern(End, Rest, State, [C|Result]);
get_pattern(End, [], State, Result) ->
get_pattern(End, [End], State, Result).
get_replacement(End, Cmd) ->
get_replacement(End, Cmd, []).
get_replacement(End, [End|Rest], Result) ->
{ok, lists:reverse(Result), Rest};
get_replacement(End, [$\\, $&|Rest], Result) ->
get_replacement(End, Rest, [$&, $\\|Result]);
get_replacement(End, [$\\, C|Rest], Result) ->
get_replacement(End, Rest, [C|Result]);
get_replacement(End, [C|Rest], Result) ->
get_replacement(End, Rest, [C|Result]);
get_replacement(End, [], Result) ->
get_replacement(End, [End], Result).
check_trailing_p([$l], St) ->
St#state{print=fun(Line, _) -> lister(Line, 0) end};
check_trailing_p([$n], St) ->
St#state{print=fun numberer/2};
check_trailing_p([$p], St) ->
St#state{print=fun(Line, _) -> io:put_chars(Line) end};
check_trailing_p([], State) ->
State;
check_trailing_p(_Other, _State) ->
error(garbage_after_command).
error(Reason) ->
throw({error, Reason}).
match(State) when State#state.dot == 0 ->
false;
match(State) ->
[Line|_] = State#state.upto_dot,
Re = State#state.pattern,
case re:run(Line#line.contents, Re, [{capture, none}]) of
match -> true;
nomatch -> false
end.
skip_blanks([$ |Rest]) ->
skip_blanks(Rest);
skip_blanks(Rest) ->
Rest.
print(Rest, [Line], St0) when Line > 0 ->
St1 = check_trailing_p(Rest, St0),
print(Line, move_to(Line-1, St1));
print(Rest, [First, Last], St0) when First > 0 ->
St1 = check_trailing_p(Rest, St0),
print(Last, move_to(First-1, St1)).
print(Last, St) when St#state.dot == Last ->
St#state{print=false};
print(Last, St0) ->
St1 = next_line(St0),
print_current(St1),
print(Last, St1).
lister(Rest, 64) ->
io:put_chars("\\\n"),
lister(Rest, 0);
lister([C|Rest], Num) ->
list_char(C),
lister(Rest, Num+1);
lister([], _) ->
ok.
list_char($\t) ->
io:put_chars("\\t");
list_char($\n) ->
io:put_chars("$\n");
list_char(C) ->
io:put_chars([C]).
numberer(Line, St) ->
io:format("~w\t~s", [St#state.dot, Line]).
save_for_undo(St) ->
St#state{undo=St#state{undo=undefined, print=false}}.
save_for_undo(St, OldSt) ->
St#state{undo=OldSt#state{undo=undefined, print=false}}.
