bnf-parser

A simple library to parse input strings into token trees based on a BNF's description.

BNF trees must first be compiled before they can be used to parse syntax trees.

Compilation

let result = BNF.parse(file, BNF.syntax);
let tree = BNF.compile(result.tree);

A compiled BNF can be saved as a JSON file and reloaded later

// Store the compiled result for later use
fs.writeFileSync(path, JSON.stringify(tree));

// Load the compiled BNF
let tree = BNF.fromJSON(
  JSON.parse( fs.readFileSync(path, 'utf8') )
);

Parsing

Running parse will return a BNF_Parse object, which contains a tree structure of BNF_SyntaxNodes. How these nodes are structured depends on the compiled BNF used to parse the syntax.

BNF: Build

Provided with BNF data, this will return a BNF_Tree with error handling.

BNF: Syntax

The BNF used by this application is a dilect of regular extensions for BNF. Most noteably it adds the not (!) opperator.

The BNF outlining the syntax of BNFs used by this system can be found here.

BNF Opperator: Not

The not operator must be before a set of brackets, and will consume characters until either the quota is met, or the pattern within the brackets successfully matches.
The quota of the not operation can be defined the same was as constants and terms via the use of +, *, ? operators.