I need to parse Javascript object definitions using Objective C.
Note that I'm NOT deserialising JSON. I need to parse bits of actual javascript source code. For example, something like this:
{ name : "Peter", phone : "" }
Note that unlike JSON, the 'name' and 'phone' don't have to be in quotes. This causes NSJSONSerialisation to fail immediately, so pretending that it's just JSON isn't going to work.
I don't suppose anyone has a solution that doesn't involve me writing an entire parser?
Related
What is the difference between reading the properties from payload. for example there is a property in the payload which is named as con_id. when i read this property like this #[payload.con_id] then it is coming as null. where as #[payload.'con_id'] is returning the value.
few other notations which i know of is #[payload['con_id']] or #[json:con_id]
which one should be used at which scenario? if there are any special cases to use any specific notation then please let me know the scenario also.
Also, what is the common notation that has to be used from a mule soft platform supported point of view.
In Mule 3 any of those syntax are valid. Except the json: evaluator is for querying json documents where as the others are for querying maps/objects. Also the json: evaluator is deprecated in Mule 3 in favor of transforming to a map and using the MEL expressions below.
payload.property
payload.'property'
payload['property']
The reason the first fails in your case, is beacaue of the special character '_'. The underscore forces the field name to be wrapped in quotes.
Typically the . notation is preferred over the [''] as its shorter for accessing map fields. And then simply wrap property names in '' for any fields with special chars.
Note in Mule 4, you don't need to transform to a map/object first. Dataweave expression replace MEL as the expression language and allow you to directly query json or any type of payload without transforming to a map first.
Inside an Objective-C method, it is possible to get the selector of the method with the keyword _cmd. Does such a thing exist for the names of arguments?
For example, if I have a method declared as such:
- (void)methodWithAnArgument:(id)foo {
...
}
Is there some sort of construct that would allow me to get access to some sort of string-like representation of the variable name? That is, not the value of foo, but something that actually reflects the variable name "foo" in a local variable inside the method.
This information doesn't appear to be stored in NSInvocation or any of its related classes (NSMethodSignature, etc), so I'm not optimistic this can be done using Apple's frameworks or the runtime. I suspect it might be possible with some sort of compile-time macro, but I'm unfamiliar with C macros so I wouldn't know where to begin.
Edit to contain more information about what I'm actually trying to do.
I'm building a tool to help make working with third-party URL schemes easier. There are two sides to how I want my API to look:
As a consumer of a URL scheme, I can call a method like [twitterHandler showUserWithScreenName:#"someTwitterHandle"];
As a creator of an app with a URL scheme, I can define my URLs in a plist dictionary, whose key-value pairs look something like #"showUserWithScreenName": #"twitter://user?screenName={screenName}".
What I'm working on now is finding the best way to glue these together. The current fully-functioning implementation of showUserWithScreenName: looks something like this:
- (void)showUserWithScreenName:(NSString *)screenName {
[self performCommand:NSStringFromSelector(_cmd) withArguments:#{#"screenName": screenName}];
}
Where performCommand:withArguments: is a method that (besides some other logic) looks up the command key in the plist (in this case "showUserWithScreenName:") and evaluates the value as a template using the passed dictionary as the values to bind.
The problem I'm trying to solve: there are dozens of methods like this that look exactly the same, but just swap out the dictionary definition to contain the correct template params. In every case, the desired dictionary key is the name of the parameter. I'm trying to find a way to minimize my boilerplate.
In practice, I assume I'm going to accept that there will be some boilerplate needed, but I can probably make it ever-so-slightly cleaner thanks to NSDictionaryOfVariableBindings (thanks #CodaFi — I wasn't familiar with that macro!). For the sake of argument, I'm curious if it would be possible to completely metaprogram this using something like forwardInvocation:, which as far as I can tell would require some way to access parameter names.
You can use componentsSeparatedByString: with a : after you get the string from NSStringFromSelector(_cmd) and use your #selector's argument names to put the arguments in the correct order.
You can also take a look at this post, which is describing the method naming conventions in Objective C
I have an attribute called 'page'. It is made up of two to three doubles, separated by commas, not spaces, with an optional '!' at the end. All of the following are valid:
page="8.5,11,3!"
page="8.5,11.4,3.1"
page="8.5,11!"
page="8.5,2.1"
I know I could use patterns, the following would work:
attribute page { xsd:string { pattern="[0-9]+(\.[0-9]+)?,[0-9]+(\.[0-9]+)(,[0-9]+(\.[0-9]+)?)?(!)?" } }
But if possible, I'd rather use something like this:
attribute page { xsd:double, ",", xsd:double, ( ",", xsd:double )?, ("!")? }
I can make the above sort-of work, using 'list':
attribute page { list { xsd:double, ",", xsd:double, ( ",", xsd:double )?, ("!")? } }
But then I end up with spaces between each of the pieces:
page="8.5 , 11 !"
Is there any way to do this without using pattern?
Relax NG has no particular rules for how simple types are defined; it is designed to be able to use simple type libraries which make such rules. So in principle, yes, you can do what you like in Relax NG: just use a simple type library that provides the functionality you seek.
In practice, you seem to be using the XSD library of simple types. And while XSD does allow the definition of list types whose values are sequences of other simple values, for the sake of simplicity in the definition and in the validator, XSD list values are broken by the parser on white space; XSD does not allow arbitrary separators for the values. So, no you cannot do what you say you would like to do, with Relax NG's XSD-based library of simple types.
Is there a way that I can instruct WCF to accept JSON that is formatted using either single quotes (as opposed to double quotes):
{
'foo': 'bar'
}
Or using non-quoted identifiers like so:
{
foo: 'bar'
}
As it is, it seems like JSON will only be accepted if it is formatted like so:
{
"foo": "bar"
}
Using either of the first two example results in a 400 (bad request).
The first two examples are invalid JSON texts.
http://www.ietf.org/rfc/rfc4627.txt
object = begin-object [ member *( value-separator member ) ]
end-object
member = string name-separator value
string = quotation-mark *char quotation-mark
quotation-mark = %x22 ; "
DataContractJsonSerializer always writes strict JSON.
At various points during deserialization (generally missing end tags for arrays or objects, or improper escaping, or improperly formatted numbers), it will accept incorrect, non-strict JSON.
However, I can tell you definitively that this is not one of those cases. DataContractJsonSerializer always requires double-quoted strings for JSON.
Hope this helps!
http://www.google.com/dictionary/json?callback=dict_api.callbacks.id100&q=test&sl=en&tl=en&restrict=pr%2Cde&client=te
(replace test with your favorite keyword)
using this i want to write simple dictionary....
problem - api give json output how i get it using java?
Simple Parsing
Per default, JSON will just produce a nested graph of maps and lists. Here is an example of default parsing:
import org.svenson.JSONParser;
// assume json to be a JSON datasets as String
Object o = JSONParser.defaultJSONParser().parse(json);
o will now contain either a map or a list instance, depending on whether the first symbol in the JSON is '{' or '['.