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better decoding of surrogates encoded in json strings

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This commit is contained in:
alisdair sullivan 2010-06-01 20:44:48 -07:00
parent 8faa7089f8
commit d7140dd6c2
5 changed files with 141 additions and 11 deletions
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30
src/jsx_utf8.erl
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@ -273,8 +273,15 @@ escaped_unicode(<<D/?encoding, Rest/binary>>,
[C, B, A])
when ?is_hex(D) ->
case erlang:list_to_integer([A, B, C, D], 16) of
X when X < 16#d800; X > 16#dfff, X < 16#fffe ->
string(Rest, Stack, Callbacks, Opts, [X] ++ String)
X when X >= 16#dc00, X =< 16#dfff ->
case check_acc_for_surrogate(String) of
false ->
string(Rest, Stack, Callbacks, Opts, [D, C, B, A, $u, ?rsolidus] ++ String)
; {Y, NewString} ->
string(Rest, Stack, Callbacks, Opts, [surrogate_to_codepoint(X, Y)] ++ NewString)
end
; X when X < 16#d800; X > 16#dfff, X < 16#fffe ->
string(Rest, Stack, Callbacks, Opts, [X] ++ String)
; _ ->
string(Rest, Stack, Callbacks, Opts, [D, C, B, A, $u, ?rsolidus] ++ String)
end;
@ -285,6 +292,25 @@ escaped_unicode(<<S/?encoding, Rest/binary>>, Stack, Callbacks, Opts, String, Ac
escaped_unicode(<<>>, Stack, Callbacks, Opts, String, Acc) ->
{incomplete, fun(Stream) -> escaped_unicode(Stream, Stack, Callbacks, Opts, String, Acc) end}.
%% upon encountering a low pair json/hex encoded value, check to see if there's a high
%% value already in the accumulator.
check_acc_for_surrogate([D, C, B, A, $u, ?rsolidus|Rest])
when ?is_hex(D), ?is_hex(C), ?is_hex(B), ?is_hex(A) ->
case erlang:list_to_integer([A, B, C, D], 16) of
X when X >=16#d800, X =< 16#dbff ->
{X, Rest};
_ ->
false
end;
check_acc_for_surrogate(_) ->
false.
%% stole this from the unicode spec
surrogate_to_codepoint(X, Y) ->
(X - 16#d800) * 16#400 + (Y - 16#dc00) + 16#10000.
%% like strings, numbers are collected in an intermediate accumulator before
%% being emitted to the callback handler. no processing of numbers is done in