BNFParser is a Backus-Naur Form Framework for Objective C written by Mike Friesen released under the Apache 2 Open Source License.

An Java version is also available.

BNFParser was inspired by the framework ParseKit by Todd Ditchendorf.

The BNFParser Framework offers 3 basic services of general interest to developers:

1. String Tokenization via the BNFTokenizerFactory and BNFToken classes

2. Property Key/Value mapper via PropertyParser

3. Text Parsing via Grammars via BNFParser see grammar syntax

1. String Tokenization

The string tokenizer breaks down any string into a series of letter/number/symbols for easy processing.

How do I use it?

NSString *text = @"The cow jumped over the moon!";
BNFTokenizerFactory *factory = [[BNFTokenizerFactory alloc] init];
BNFToken *token = [factory tokens:text];
while (token) {
  NSLog(@"TOKEN %@", [token stringValue]);
  token = [token nextToken];
}

2. PropertyParser

Uses the string tokenizer to parse a string and create key/value mapping based on the '=' symbol.

How do I use it?

NSString *text = @"sample key = sample value";
PropertyParser *propertyParser = [[PropertyParser alloc] init];
NSMutableDictionary *keyValueMap = [propertyParser parse:text];
STAssertNotNil([keyValueMap objectForKey:@"sample key"], @"expect key exists");

3. Text Parsing via Grammars

BNFParser currently only ships with a JSON grammar so the example are based on that.

How do I use it?

// Create String Tokens
NSString *text = @"{ \"key\":\"value\"}";
BNFTokenizerFactory *factory = [[BNFTokenizerFactory alloc] init];
BNFToken *token = [factory tokens:text];

// Create Backus-Naur Form State Definitions
BNFStateDefinitionFactory *sdf = [[BNFStateDefinitionFactory alloc] init];
NSMutableDictionary *map = [stateDefinitionFactory json];

// Run Tokens through Parser
BNFParser *parser = [[BNFParser alloc] initWithStateDefinitions:dic];
BNFParseResult *result = [parser parse:token];

// Verify results

// verify text passes grammar:
STAssertTrue([result success], @"assume success"); 

// the "first" token, same as the token returned from the tokenizer factory:
STAssertNotNil([result top], @"assume not nil"); 

// the "first" error token, this token and any afterwards are considered to not have passed the grammar:
STAssertNil([result error], @"assume nil");  

Bugs and Feedback

For bugs, questions and discussions please use the Github Issues.

Contributing

We love contributions! If you'd like to contribute please submit a pull request via Github.

In the Wild

Applications (OS X)

GoJSON - JSON Editor

LICENSE

This library is distributed under the Apache 2 Open Source License.