edn-objc

A work-in-progress implementation of edn-format for Objective-C/Foundation platforms (e.g. iOS and OSX).

Current design goals are completeness and spec adherence. Any valid edn data deserialized into Cocoa/EDN objects should be serialized back to the same edn UTF-8 data (barring whitespace, both in strings and amidst the edn data). This includes the 'root'; the top-level objects that are not within any root container.

Tagged elements (such as the built-in uuid and inst) may be converted to concrete Cocoa objects (again, NSUUID and NSDate) via implementation of the EDNRepresentation protocol, and registering with EDNRegistry during +load. See the NSUUID+EDN and NSDate+EDN implementations for detail.

'Unknown' tagged elements will be converted to/from EDNTaggedElement during de/serialization.

Objects that implement keyed NSCoding will be written out as a map tagged with #edn-objc/[the class name]. Objects serialized this way may also be reconstituted at read time. Secure decoding is not yet supported.

Numbers are read exclusively into NSDecimalNumber and seem to afford around 128 bits of mantissa. So far, no support for arbitrary precision integers. Ratios are also supported by default, but disabled in 'strict' mode.

Lazy deserialization from NSInputStream is supported, and lazy parsing can be consumed by multiple threads using the root object's -objectEnumerator. Lazy parsing is limited to top-level objects at this time; a given object will be fully parsed into memory immediately.

Note: very little testing has occurred so far; the goal was to get a roughed-in version of reading and writing behind a decent interface out into the world. YMMV on OSX and iOS < 6.1. If you see an issue, I'd love to see a test that exposes it. Notably, using NSUUID for #uuid creates a dependency on iOS 6+.

##Entry points

The primary entry point is EDNSerialization, which exposes an NSJSONSerialization-style API for parsing strings, data, or streams, as well as writing object graphs back to the same.

There are a few categories defined; NSData, NSInputStream, and NSString each have an -ednObject category method that will attempt to parse the instance (returning nil on failure). NSObject defines -ednString and -ednData methods to attempt to write out the object as the root.

The NSObject category also defines a metadata property, allowing the association of a metadata dictionary. This will be set at read time and written out at serialization time.

##Object Mapping

edn ⇌ Cocoa

#####'Pure' Cocoa mappings

string ⇌ NSString (surprise!)

vector ⇌ NSArray

map ⇌ NSDictionary

integer, floating point ⇌ NSDecimalNumber

set ⇌ NSSet

nil ⇌ NSNull

• nil is also written out for nil/NULL pointers, but currently read in as NSNull.

booleans ⇌ CFBoolean (bridged with NSNumber)

• Specifically: kCFBooleanTrue and kCFBooleanFalse.

#inst ⇌ NSDate

#uuid ⇌ NSUUID

bonus! metadata ⇌ NSDictionary

#####Custom object mappings

root (top-level) EDNRoot

list ⇌ EDNList

character ⇌ EDNCharacter

symbol ⇌ EDNSymbol

keyword ⇌ EDNKeyword

arbitrary tags ⇌ EDNTaggedElement

ratio ⇌ EDNRatio

###License

This project is licensed under the Eclipse Public License, v1.