SBJsonStreamParser.h

/*
 Copyright (c) 2010, Stig Brautaset.
 All rights reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are
 met:

   Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.

   Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.

   Neither the name of the the author nor the names of its contributors
   may be used to endorse or promote products derived from this software
   without specific prior written permission.

 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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 */

#import <Foundation/Foundation.h>

@class SBJsonStreamParser;
@class SBJsonStreamParserState;

typedef enum {
	SBJsonStreamParserComplete,
	SBJsonStreamParserWaitingForData,
	SBJsonStreamParserError,
} SBJsonStreamParserStatus;


/**
 Delegate for interacting directly with the stream parser

 You will most likely find it much more convenient to implement the
 SBJsonStreamParserAdapterDelegate protocol instead.
 */
@protocol SBJsonStreamParserDelegate

/// Called when object start is found
- (void)parserFoundObjectStart:(SBJsonStreamParser*)parser;

/// Called when object key is found
- (void)parser:(SBJsonStreamParser*)parser foundObjectKey:(NSString*)key;

/// Called when object end is found
- (void)parserFoundObjectEnd:(SBJsonStreamParser*)parser;

/// Called when array start is found
- (void)parserFoundArrayStart:(SBJsonStreamParser*)parser;

/// Called when array end is found
- (void)parserFoundArrayEnd:(SBJsonStreamParser*)parser;

/// Called when a boolean value is found
- (void)parser:(SBJsonStreamParser*)parser foundBoolean:(BOOL)x;

/// Called when a null value is found
- (void)parserFoundNull:(SBJsonStreamParser*)parser;

/// Called when a number is found
- (void)parser:(SBJsonStreamParser*)parser foundNumber:(NSNumber*)num;

/// Called when a string is found
- (void)parser:(SBJsonStreamParser*)parser foundString:(NSString*)string;

@end


/**
 Parse a stream of JSON data.

 Using this class directly you can reduce the apparent latency for each
 download/parse cycle of documents over a slow connection. You can start
 parsing *and return chunks of the parsed document* before the entire
 document is downloaded.

 Using this class is also useful to parse huge documents on disk
 bit by bit so you don't have to keep them all in memory.

 JSON is mapped to Objective-C types in the following way:

 - null    -> NSNull
 - string  -> NSString
 - array   -> NSMutableArray
 - object  -> NSMutableDictionary
 - true    -> NSNumber's -numberWithBool:YES
 - false   -> NSNumber's -numberWithBool:NO
 - integer up to 19 digits -> NSNumber's -numberWithLongLong:
 - all other numbers       -> NSDecimalNumber

 Since Objective-C doesn't have a dedicated class for boolean values,
 these turns into NSNumber instances. However, since these are
 initialised with the -initWithBool: method they round-trip back to JSON
 properly. In other words, they won't silently suddenly become 0 or 1;
 they'll be represented as 'true' and 'false' again.

 As an optimisation integers up to 19 digits in length (the max length
 for signed long long integers) turn into NSNumber instances, while
 complex ones turn into NSDecimalNumber instances. We can thus avoid any
 loss of precision as JSON allows ridiculously large numbers.

 See also SBJsonStreamParserAdapter for more information.

 */
@interface SBJsonStreamParser : NSObject

@property (nonatomic, unsafe_unretained) SBJsonStreamParserState *state; // Private
@property (nonatomic, readonly, strong) NSMutableArray *stateStack; // Private

/**
 Expect multiple documents separated by whitespace

 Normally the -parse: method returns SBJsonStreamParserComplete when it's found a complete JSON document.
 Attempting to parse any more data at that point is considered an error. ("Garbage after JSON".)

 If you set this property to true the parser will never return SBJsonStreamParserComplete. Rather,
 once an object is completed it will expect another object to immediately follow, separated
 only by (optional) whitespace.

 */
@property BOOL supportMultipleDocuments;

/**
 Delegate to receive messages

 The object set here receives a series of messages as the parser breaks down the JSON stream
 into valid tokens.

 Usually this should be an instance of SBJsonStreamParserAdapter, but you can
 substitute your own implementation of the SBJsonStreamParserDelegate protocol if you need to.
 */
@property (unsafe_unretained) id<SBJsonStreamParserDelegate> delegate;

/**
 The max parse depth

 If the input is nested deeper than this the parser will halt parsing and return an error.

 Defaults to 32.
 */
@property NSUInteger maxDepth;

/// Holds the error after SBJsonStreamParserError was returned
@property (copy) NSString *error;

/**
 Parse some JSON

 The JSON is assumed to be UTF8 encoded. This can be a full JSON document, or a part of one.

 @param data An NSData object containing the next chunk of JSON

 @return
 - SBJsonStreamParserComplete if a full document was found
 - SBJsonStreamParserWaitingForData if a partial document was found and more data is required to complete it
 - SBJsonStreamParserError if an error occured. (See the error property for details in this case.)

 */
- (SBJsonStreamParserStatus)parse:(NSData*)data;

@end