Name: couchdb-jiffy
Owner: Cloudant
Description: Mirror of Apache CouchDB
Created: 2015-07-01 17:25:22.0
Updated: 2016-08-03 18:06:30.0
Pushed: 2016-08-03 18:06:29.0
Homepage: null
Size: 2470
Language: Erlang
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A JSON parser as a NIF. This is a complete rewrite of the work I did in EEP0018 that was based on Yajl. This new version is a hand crafted state machine that does its best to be as quick and efficient as possible while not placing any constraints on the parsed JSON.
Jiffy is a simple API. The only thing that might catch you off guard
is that the return type of jiffy:encode/1 is an iolist even though
it returns a binary most of the time.
A quick note on unicode. Jiffy only understands UTF-8 in binaries. End of story.
Errors are raised as exceptions.
Eshell V5.8.2 (abort with ^G)
1> jiffy:decode(<<"{\"foo\": \"bar\"}">>).
{[{<<"foo">>,<<"bar">>}]}
2> Doc = {[{foo, [<<"bing">>, 2.3, true]}]}.
{[{foo,[<<"bing">>,2.3,true]}]}
3> jiffy:encode(Doc).
<<"{\"foo\":[\"bing\",2.3,true]}">>
jiffy:decode/1,2jiffy:decode(IoData)jiffy:decode(IoData, Options)The options for decode are:
return_maps - Tell Jiffy to return objects using the maps data type
on VMs that support it. This raises an error on VMs that don't support
maps.{null_term, Term} - Returns the specified Term instead of null
when decoding JSON. This is for people that wish to use undefined
instead of null.use_nil - Returns the atom nil instead of null when decoding
JSON. This is a short hand for {null_term, nil}.return_trailer - If any non-whitespace is found after the first
JSON term is decoded the return value of decode/2 becomes
{has_trailer, FirstTerm, RestData::iodata()}. This is useful to
decode multiple terms in a single binary.{bytes_per_red, N} where N >= 0 - This controls the number of
bytes that Jiffy will process as an equivalent to a reduction. Each
20 reductions we consume 1% of our allocated time slice for the current
process. When the Erlang VM indicates we need to return from the NIF.{bytes_per_iter, N} where N >= 0 - Backwards compatible option
that is converted into the bytes_per_red value.jiffy:encode/1,2jiffy:encode(EJSON)jiffy:encode(EJSON, Options)where EJSON is a valid representation of JSON in Erlang according to the table below.
The options for encode are:
uescape - Escapes UTF-8 sequences to produce a 7-bit clean outputpretty - Produce JSON using two-space indentationforce_utf8 - Force strings to encode as UTF-8 by fixing broken
surrogate pairs and/or using the replacement character to remove
broken UTF-8 sequences in data.use_nil - Encode's the atom nil as null.escape_forward_slashes - Escapes the / character which can be
useful when encoding URLs in some cases.{bytes_per_red, N} - Refer to the decode options{bytes_per_iter, N} - Refer to the decode optionsErlang JSON Erlang
==========================================================================
null -> null -> null
true -> true -> true
false -> false -> false
"hi" -> [104, 105] -> [104, 105]
<<"hi">> -> "hi" -> <<"hi">>
hi -> "hi" -> <<"hi">>
1 -> 1 -> 1
1.25 -> 1.25 -> 1.25
[] -> [] -> []
[true, 1.0] -> [true, 1.0] -> [true, 1.0]
{[]} -> {} -> {[]}
{[{foo, bar}]} -> {"foo": "bar"} -> {[{<<"foo">>, <<"bar">>}]}
{[{<<"foo">>, <<"bar">>}]} -> {"foo": "bar"} -> {[{<<"foo">>, <<"bar">>}]}
#{<<"foo">> => <<"bar">>} -> {"foo": "bar"} -> #{<<"foo">> => <<"bar">>}
N.B. The last entry in this table is only valid for VM's that support
the maps data type (i.e., 17.0 and newer) and client code must pass
the return_maps option to jiffy:decode/2.
Jiffy should be in all ways an improvement over EEP0018. It no longer imposes limits on the nesting depth. It is capable of encoding and decoding large numbers and it does quite a bit more validation of UTF-8 in strings.