Myna - Recursive Descent Parsing Library for JavaScript

Myna is an easy to use recursive-descent parsing library for JavaScript (EcmaScript 5.1) written in TypeScript.

This web-site was made using Myna tools to:

1. Parse and convert Markdown into HTML
2. Parse and expand Mustache style templates
3. Convert HTML characters into escape codes

Myna features:

• Myna is a JavaScript library not a code generator
• Parsing automatically creates an abstract syntax tree (AST)
• No separate tokenization phase
• Competitive performance with other libraries
• Many sample grammars and example tools.
• Functions for generating a PEG representation of the grammar, or the AST schema

Using Myna

Below is an example of how to use Myna from Node.JS in a single self-contained example:

// Load the Myna module and all grammars
var m = require('myna-parser');

// Load the JSON grammar
require('myna-parser/grammars/grammar_json')(m);

// Get the JSON parser 
var parser = m.parsers.json; 

// Define some input 
var input = '{ "integer":42, "greeting":"hello", "truth":false, "array":[1,2,3] }';

// Output the generated AST 
console.log(parser(input).toString());

Writing a Grammar

The following example shows how to use Myna with a custom Grammar:

// Reference the Myna module
var m = require('myna-parser');

// Construct a grammar object 
var g = new function() 
{
    this.textdata   = m.notChar('\n\r"' + delimiter);    
    this.quoted     = m.doubleQuoted(m.notChar('"').or('""').zeroOrMore);
    this.field      = this.textdata.or(this.quoted).zeroOrMore.ast;
    this.record     = this.field.delimited(delimiter).ast;
    this.file       = this.record.delimited(m.newLine).ast;   
}

// Let consumers of the Myna module access 
m.registerGrammar("csv", g, g.file);

// Get the parser 
var parser = m.parsers.csv; 
var input = 'a,1,"hello"\nb,2,"goodbye"';
console.log(parser(input).toString());

Only rules that are defined with the .ast property will create nodes in the output parse tree. This saves the work of having to convert from a Concrete Syntax Tree (CST) to an Abstract Syntax Tree (AST).