new readme, with new api
This commit is contained in:
alisdair sullivan
parent
b016087ceb
commit
bfe9f2678c
1 changed files with 167 additions and 9 deletions
176
README.markdown
176
README.markdown
|
|
@ -3,25 +3,57 @@ jsx
|
|||
|
||||
jsx is an event based json parser. basically [yajl][1], but in erlang. born from a need for a stream based, incremental parser capable of outputting a number of representations. see [the homepage][2] for examples of what it can do.
|
||||
|
||||
it also includes an implementation of [eep0018][3], a pretty printer, a verifier and a few stray functions to help you write your own json gizmos.
|
||||
|
||||
|
||||
### usage ###
|
||||
|
||||
jsx provides an iterator based api that returns tuples of the form `{event, Event, Next}` where `Event` is an atom or tuple (see below) representing the json structure or value encountered. `Next` is a zero arity function that returns the next tuple in the sequence when called. it is stream based, and can also return the tuple `{incomplete, More}` to signify that input is exhausted. `More` is an arity one function that, when called with another binary, attempts to continue parsing treating the new binary as the tail of the preceding binary. errors in the json document are represented by the tuple `{error, badjson}`
|
||||
|
||||
Parser = jsx:parser(),
|
||||
{event, start_array, A} = Parser(<<"[ true, 1, "hello world" ]">>),
|
||||
{event, {literal, true}, B} = A(),
|
||||
{event, {integer, "1"}, C} = B(),
|
||||
{event, {string, "hello world"}, D} = C(),
|
||||
{event, end_array, E} = D(),
|
||||
{event, end_json, F} = E(),
|
||||
{incomplete, More} = F().
|
||||
the following module
|
||||
|
||||
-module(jsx_ex).
|
||||
|
||||
-export([simple_decode/1]).
|
||||
|
||||
simple_decode(JSON) when is_binary(JSON) ->
|
||||
P = jsx:parser(),
|
||||
decode(P(JSON), []).
|
||||
|
||||
decode({event, end_json, _Next}, Acc) ->
|
||||
lists:reverse(Acc);
|
||||
decode({event, Event, Next}, Acc) ->
|
||||
decode(Next(), [Event] ++ Acc).
|
||||
|
||||
produces the following output:
|
||||
|
||||
1> jsx_ex:simple_decode(
|
||||
<<"{
|
||||
\"dead rock stars\": [\"kurt cobain\", \"elliott smith\", \"nicky wire\"],
|
||||
\"total\": 3.0,
|
||||
\"courtney killed kurt\": true
|
||||
}">>).
|
||||
[start_object,
|
||||
{key,"dead rock stars"},
|
||||
start_array,
|
||||
{string,"kurt cobain"},
|
||||
{string,"elliott smith"},
|
||||
{string,"nicky wire"},
|
||||
end_array,
|
||||
{key,"total"},
|
||||
{float,"3.0"},
|
||||
{key,"courtney killed kurt"},
|
||||
{literal,true},
|
||||
end_object]
|
||||
|
||||
|
||||
|
||||
jsx is stream based and allows the parsing of naked, unwrapped json values. together, this presents a problem with streams that contain numbers ie: "123". returning at end of input means clients need to be able to invalidate the `{integer, ...}` and `end_json` events and replace them in case of more input of the form "456", for example. instead, jsx doesn't return those events until an unambiguous end of value or input is reached. instead, `{incomplete, More}` will be returned. parsing can be explicitly terminated with `More(end_stream)` or by ending all naked numbers with whitespace. note that this is only a problem with json numbers not wrapped in a containing object or array and that calling `More(end_stream)` in any other context will result in an error
|
||||
|
||||
|
||||
### types ###
|
||||
|
||||
|
||||
unicode_codepoint() = 0..16#10ffff
|
||||
|
||||
jsx_event() = start_object
|
||||
|
|
@ -52,7 +84,7 @@ jsx is stream based and allows the parsing of naked, unwrapped json values. toge
|
|||
returns a function that takes a binary and attempts to parse it as an encoded
|
||||
json document
|
||||
|
||||
the available options are:
|
||||
options:
|
||||
|
||||
{comments, true | false}
|
||||
if true, json documents that contain c style (/* ... */) comments
|
||||
|
|
@ -81,6 +113,131 @@ jsx is stream based and allows the parsing of naked, unwrapped json values. toge
|
|||
multiple documents to be parsed correctly
|
||||
|
||||
|
||||
term_to_json(eep0018()) -> binary()
|
||||
term_to_json(eep0018(), Options) -> binary()
|
||||
Options = [Opt]
|
||||
Opt -- see below
|
||||
|
||||
takes the erlang representation of a json object (as defined in eep0018) and
|
||||
returns a (binary encoded) json string
|
||||
|
||||
options:
|
||||
|
||||
{strict, true | false}
|
||||
by default, attempting to convert unwrapped json values (numbers,
|
||||
strings and the atoms true, false and null) result in a badarg exception.
|
||||
if strict equals false, these are instead json encoded. default is false
|
||||
|
||||
{encoding, utf8 | utf16 | {utf16, little} | utf32 | {utf32, little} }
|
||||
the encoding of the resulting binary. default is utf8
|
||||
|
||||
space
|
||||
{space, N}
|
||||
place N spaces after each colon and comma in the resulting binary. space
|
||||
implies {space, 1}. default is zero
|
||||
|
||||
indent
|
||||
{indent, N}
|
||||
indent each 'level' of the json structure by N spaces. indent implies
|
||||
{indent, 1}. default is zero
|
||||
|
||||
|
||||
json_to_term(binary()) -> eep0018()
|
||||
json_to_term(binary(), Options) -> eep0018()
|
||||
Options = [Opt]
|
||||
Opt -- see below
|
||||
|
||||
takes a binary and attempts to decode it into the eep0018 representation
|
||||
|
||||
options:
|
||||
|
||||
{strict, true | false}
|
||||
by default, attempting to convert unwrapped json values (numbers, strings and
|
||||
the atoms true, false and null) result in a badarg exception. if strict equals
|
||||
false, these are instead decoded to their equivalent eep0018 value. default is
|
||||
false
|
||||
|
||||
{encoding, auto | utf8 | utf16 | {utf16, little} | utf32 | {utf32, little} }
|
||||
assume the binary is encoded using the specified binary. default is auto, which
|
||||
attempts to autodetect the encoding
|
||||
|
||||
{comments, true | false}
|
||||
if true, json documents that contain c style (/* ... */) comments
|
||||
will be parsed as if they did not contain any comments. default is
|
||||
false
|
||||
|
||||
{label, atom | existing_atom | binary}
|
||||
json keys (labels) are decoded to utf8 encoded binaries, atoms or
|
||||
existing_atoms (atom if it exists, binary otherwise) as specified by
|
||||
this option. default is binary
|
||||
|
||||
{float, true | false}
|
||||
return all numbers as floats. default is false
|
||||
|
||||
is_json(binary()) -> true | false
|
||||
is_json(binary(), Options) -> true | false
|
||||
Options = [Opt]
|
||||
Opt -- see below
|
||||
|
||||
returns true if the binary is an encoded json string, false otherwise
|
||||
|
||||
options:
|
||||
|
||||
{strict, true | false}
|
||||
by default, unwrapped json values (numbers, strings and the atoms
|
||||
true, false and null) return false. if strict equals true, is_json
|
||||
returns true. default is false
|
||||
|
||||
{encoding, auto | utf8 | utf16 | {utf16, little} | utf32 | {utf32, little} }
|
||||
assume the binary is encoded using the specified binary. default is auto,
|
||||
which attempts to autodetect the encoding
|
||||
|
||||
{comments, true | false}
|
||||
if true, json documents that contain c style (/* ... */) comments
|
||||
will be parsed as if they did not contain any comments. default is
|
||||
false
|
||||
|
||||
format(binary()) -> binary()
|
||||
format(binary(), Options) -> binary()
|
||||
Options = [Opt]
|
||||
Opt -- see below
|
||||
|
||||
formats a binary encoded json string according to the options chose. the
|
||||
defaults will produced a string stripped of all whitespace
|
||||
|
||||
options:
|
||||
|
||||
{strict, true | false}
|
||||
by default, unwrapped json values (numbers, strings and the atoms
|
||||
true, false and null) result in an error. if strict equals true, they
|
||||
are treated as valid json. default is false
|
||||
|
||||
{encoding, auto | utf8 | utf16 | {utf16, little} | utf32 | {utf32, little} }
|
||||
assume the binary is encoded using the specified binary. default is auto,
|
||||
which attempts to autodetect the encoding
|
||||
|
||||
{output_encoding, utf8 | utf16 | {utf16, little} | utf32 | {utf32, little} }
|
||||
the encoding of the resulting binary. default is utf8
|
||||
|
||||
{comments, true | false}
|
||||
if true, json documents that contain c style (/* ... */) comments
|
||||
will be parsed as if they did not contain any comments. default is
|
||||
false
|
||||
|
||||
space
|
||||
{space, N}
|
||||
place N spaces after each colon and comma in the resulting binary. space
|
||||
implies {space, 1}. default is zero
|
||||
|
||||
indent
|
||||
{indent, N}
|
||||
indent each 'level' of the json structure by N spaces. indent implies
|
||||
{indent, 1}. default is zero
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
### installation ###
|
||||
|
||||
`make` to build jsx
|
||||
|
|
@ -101,3 +258,4 @@ jsx supports utf8, utf16 (little and big endian) and utf32 (little and big endia
|
|||
|
||||
[1]: http://lloyd.github.com/yajl
|
||||
[2]: http://talentdeficit.github.com/jsx
|
||||
[3]: http://eep0018
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue