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-file("peg_includes.hrl", 1).
-type index() :: {{line, pos_integer()}, {column, pos_integer()}}.
-type input() :: binary().
-type parse_failure() :: {fail, term()}.
-type parse_success() :: {term(), input(), index()}.
-type parse_result() :: parse_failure() | parse_success().
-type parse_fun() :: fun((input(), index()) -> parse_result()).
-type xform_fun() :: fun((input(), index()) -> term()).
-spec p(input(), index(), atom(), parse_fun(), xform_fun()) -> parse_result().
p(Inp, StartIndex, Name, ParseFun, TransformFun) ->
case get_memo(StartIndex, Name) of % See if the current reduction is memoized
{ok, Memo} -> %Memo; % If it is, return the stored result
Memo;
_ -> % If not, attempt to parse
Result = case ParseFun(Inp, StartIndex) of
{fail,_} = Failure -> % If it fails, memoize the failure
Failure;
{Match, InpRem, NewIndex} -> % If it passes, transform and memoize the result.
Transformed = TransformFun(Match, StartIndex),
{Transformed, InpRem, NewIndex}
end,
memoize(StartIndex, Name, Result),
Result
end.
-spec setup_memo() -> ets:tid().
setup_memo() ->
put({parse_memo_table, ?MODULE}, ets:new(?MODULE, [set])).
-spec release_memo() -> true.
release_memo() ->
ets:delete(memo_table_name()).
-spec memoize(index(), atom(), parse_result()) -> true.
memoize(Index, Name, Result) ->
Memo = case ets:lookup(memo_table_name(), Index) of
[] -> [];
[{Index, Plist}] -> Plist
end,
ets:insert(memo_table_name(), {Index, [{Name, Result}|Memo]}).
-spec get_memo(index(), atom()) -> {ok, term()} | {error, not_found}.
get_memo(Index, Name) ->
case ets:lookup(memo_table_name(), Index) of
[] -> {error, not_found};
[{Index, Plist}] ->
case proplists:lookup(Name, Plist) of
{Name, Result} -> {ok, Result};
_ -> {error, not_found}
end
end.
-spec memo_table_name() -> ets:tid().
memo_table_name() ->
get({parse_memo_table, ?MODULE}).
-ifdef(p_eof).
-spec p_eof() -> parse_fun().
p_eof() ->
fun(<<>>, Index) -> {eof, [], Index};
(_, Index) -> {fail, {expected, eof, Index}} end.
-endif.
-ifdef(p_optional).
-spec p_optional(parse_fun()) -> parse_fun().
p_optional(P) ->
fun(Input, Index) ->
case P(Input, Index) of
{fail,_} -> {[], Input, Index};
{_, _, _} = Success -> Success
end
end.
-endif.
-ifdef(p_not).
-spec p_not(parse_fun()) -> parse_fun().
p_not(P) ->
fun(Input, Index)->
case P(Input,Index) of
{fail,_} ->
{[], Input, Index};
{Result, _, _} -> {fail, {expected, {no_match, Result},Index}}
end
end.
-endif.
-ifdef(p_assert).
-spec p_assert(parse_fun()) -> parse_fun().
p_assert(P) ->
fun(Input,Index) ->
case P(Input,Index) of
{fail,_} = Failure-> Failure;
_ -> {[], Input, Index}
end
end.
-endif.
-ifdef(p_seq).
-spec p_seq([parse_fun()]) -> parse_fun().
p_seq(P) ->
fun(Input, Index) ->
p_all(P, Input, Index, [])
end.
-spec p_all([parse_fun()], input(), index(), [term()]) -> parse_result().
p_all([], Inp, Index, Accum ) -> {lists:reverse( Accum ), Inp, Index};
p_all([P|Parsers], Inp, Index, Accum) ->
case P(Inp, Index) of
{fail, _} = Failure -> Failure;
{Result, InpRem, NewIndex} -> p_all(Parsers, InpRem, NewIndex, [Result|Accum])
end.
-endif.
-ifdef(p_choose).
-spec p_choose([parse_fun()]) -> parse_fun().
p_choose(Parsers) ->
fun(Input, Index) ->
p_attempt(Parsers, Input, Index, none)
end.
-spec p_attempt([parse_fun()], input(), index(), none | parse_failure()) -> parse_result().
p_attempt([], _Input, _Index, Failure) -> Failure;
p_attempt([P|Parsers], Input, Index, FirstFailure)->
case P(Input, Index) of
{fail, _} = Failure ->
case FirstFailure of
none -> p_attempt(Parsers, Input, Index, Failure);
_ -> p_attempt(Parsers, Input, Index, FirstFailure)
end;
Result -> Result
end.
-endif.
-ifdef(p_zero_or_more).
-spec p_zero_or_more(parse_fun()) -> parse_fun().
p_zero_or_more(P) ->
fun(Input, Index) ->
p_scan(P, Input, Index, [])
end.
-endif.
-ifdef(p_one_or_more).
-spec p_one_or_more(parse_fun()) -> parse_fun().
p_one_or_more(P) ->
fun(Input, Index)->
Result = p_scan(P, Input, Index, []),
case Result of
{[_|_], _, _} ->
Result;
_ ->
{fail, {expected, Failure, _}} = P(Input,Index),
{fail, {expected, {at_least_one, Failure}, Index}}
end
end.
-endif.
-ifdef(p_label).
-spec p_label(atom(), parse_fun()) -> parse_fun().
p_label(Tag, P) ->
fun(Input, Index) ->
case P(Input, Index) of
{fail,_} = Failure ->
Failure;
{Result, InpRem, NewIndex} ->
{{Tag, Result}, InpRem, NewIndex}
end
end.
-endif.
-ifdef(p_scan).
-spec p_scan(parse_fun(), input(), index(), [term()]) -> {[term()], input(), index()}.
p_scan(_, <<>>, Index, Accum) -> {lists:reverse(Accum), <<>>, Index};
p_scan(P, Inp, Index, Accum) ->
case P(Inp, Index) of
{fail,_} -> {lists:reverse(Accum), Inp, Index};
{Result, InpRem, NewIndex} -> p_scan(P, InpRem, NewIndex, [Result | Accum])
end.
-endif.
-ifdef(p_string).
-spec p_string(binary()) -> parse_fun().
p_string(S) ->
Length = erlang:byte_size(S),
fun(Input, Index) ->
try
<<S:Length/binary, Rest/binary>> = Input,
{S, Rest, p_advance_index(S, Index)}
catch
error:{badmatch,_} -> {fail, {expected, {string, S}, Index}}
end
end.
-endif.
-ifdef(p_anything).
-spec p_anything() -> parse_fun().
p_anything() ->
fun(<<>>, Index) -> {fail, {expected, any_character, Index}};
(Input, Index) when is_binary(Input) ->
<<C/utf8, Rest/binary>> = Input,
{<<C/utf8>>, Rest, p_advance_index(<<C/utf8>>, Index)}
end.
-endif.
-ifdef(p_charclass).
-spec p_charclass(string() | binary()) -> parse_fun().
p_charclass(Class) ->
{ok, RE} = re:compile(Class, [unicode, dotall]),
fun(Inp, Index) ->
case re:run(Inp, RE, [anchored]) of
{match, [{0, Length}|_]} ->
{Head, Tail} = erlang:split_binary(Inp, Length),
{Head, Tail, p_advance_index(Head, Index)};
_ -> {fail, {expected, {character_class, binary_to_list(Class)}, Index}}
end
end.
-endif.
-ifdef(p_regexp).
-spec p_regexp(binary()) -> parse_fun().
p_regexp(Regexp) ->
{ok, RE} = re:compile(Regexp, [unicode, dotall, anchored]),
fun(Inp, Index) ->
case re:run(Inp, RE) of
{match, [{0, Length}|_]} ->
{Head, Tail} = erlang:split_binary(Inp, Length),
{Head, Tail, p_advance_index(Head, Index)};
_ -> {fail, {expected, {regexp, binary_to_list(Regexp)}, Index}}
end
end.
-endif.
-ifdef(line).
-spec line(index() | term()) -> pos_integer() | undefined.
line({{line,L},_}) -> L;
line(_) -> undefined.
-endif.
-ifdef(column).
-spec column(index() | term()) -> pos_integer() | undefined.
column({_,{column,C}}) -> C;
column(_) -> undefined.
-endif.
-spec p_advance_index(input() | unicode:charlist() | pos_integer(), index()) -> index().
p_advance_index(MatchedInput, Index) when is_list(MatchedInput) orelse is_binary(MatchedInput)-> % strings
lists:foldl(fun p_advance_index/2, Index, unicode:characters_to_list(MatchedInput));
p_advance_index(MatchedInput, Index) when is_integer(MatchedInput) -> % single characters
{{line, Line}, {column, Col}} = Index,
case MatchedInput of
$\n -> {{line, Line+1}, {column, 1}};
_ -> {{line, Line}, {column, Col+1}}
end.
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