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oli.js Build Status Dependency Status NPM version

Oli language parser and compiler for node and the browser

Language version0.1


Multi-purpose high level Oli language parser and compiler for node.js and the browser, which implements the latest language specification

Oli.js provides a general parsing infraestructure to be integrated and consumed from other applications that uses the Oli syntax for specific purposes, like parsing own DSL

Aditionally it provides a rich featured high and intermediate level programmatic API and a rich command-line interface

Note: it's still a beta implementation! A full compiler re-designing process is pending


  • Powerful parser based on parsing grammar expressions
  • Smart compiler with smart type inference
  • Detailed parsing errors
  • Runs on node.js and the browser
  • High and intermediate level featured API
  • Featured command-line interface
  • Heavily tested with high coverage
  • No third party dependencies
  • Official language specification implementation
  • Good performance (run grunt bench)



$ npm install oli

For CLI usage only, it's recommented you install it as global package

$ npm install -g oli


$ bower install oli

Or load the script remotely (just for testing or development)

<script src="//"></script>

Then you can create script tags with text/oli MIME type

<script type="text/oli" src="path/to/file.oli"></script>

It will automatically fetch and parse the oli sources and make it available from oli.scripts. To disable the automatic parsing, just add data-ignore attribute in the script tag


  • Node.js >= 0.8.0
  • Chrome
  • Firefox
  • Safari >= 5
  • Opera >= 11.6
  • IE >= 9


  • Parser
    • Top-down parsing (based on PEG strategy)
    • AST
    • Configurable parsing options
    • Errors
    • Unicode expressions
    • [*] Indentation based parsing
  • Compiler
    • AST walker
    • Memory register
    • Intermediate code transpiler
    • Code generator
    • [*] Errors
    • [_] Interpreter
    • [_] Optimiser
    • [_] Event-driven
  • Interfaces
    • API
    • CLI
    • REPL
  • Serializer
    • [_] JSON to Oli
    • [_] Concret Syntax Tree to Oli
  • Engines
    • Node.js
    • Browsers
    • [?] Rhino

Upcoming features

There are important features in Oli language spec 0.2. You can see the future features discussion here

A summary about most important features that will be implemented

  • Interpolated code expressions (oli/#3)
  • Generic helper functions (random, string format, date format...)
  • Helpers functions extension via API
  • Block scope references (oli/#18)
  • Indentation-based parsing (oli/#5)
  • Date as first-class primitive type (oli/#2)

Command-line interface

Usage: oli [options] path/to/file.oli
  -h, --help           output usage information
  -V, --version        output the version number
  -p, --parse          parse and return the result as JSON
  -t, --tokens         parse and return a collection of the tokens as JSON
  -o, --output <file>  write output into a file instead of stdout
  -a, --ast            return the parsed AST serialized as JSON
  -i, --in-line        parse in-line argument as string
  -d, --indent <size>  JSON output indent size. Default to 2
  -s, --stdin          Read source from stdin
  -r, --repl           use the interactive read-eval-print loop interface
  $ oli file.oli > file.result.json
  $ oli file.oli -o file.result.json
  $ oli --ast file.oli
  $ oli --tokens file.oli
  $ oli --in-line "hello: oli!" > result.json
  $ oli -s < file.oli


Run $ oli without arguments to play with the REPL interface

$ oli
Oli experimental REPL interface
Type "examples" to see code examples
oli> - oli, rules, yes

Programmatic API


Require the module

var oli = require('oli')

Simple parsing

var code = 'message: - hello, oli!'
try {
  var result = oli.parse(code)
} catch (e) {
  console.error('Error while parsing:', e.message)
console.log(result) // => { message: [ "hello", "oli!" ] } } 

Binding a custom context to the compiler

var code = 'directory: *env.HOME'
var result = oli.parse(code, {
  locals: {
    env: process.env

parse(code, options)

Alias: transpile Return: mixed

Parse and process the given code performing an end-to-end compilation and return the final result, that will be usually an object with the equivalent scheme tree equivalent representation of the Oli source code

ast(code, options)

Alias: parseAST Return: object

This is the most low-level API method. It returns an object that represent the parsed abstract-syntax tree

Note: AST node types or tree data structures can change between minor versions, as the parser is still beta. Please be aware with that in order to prevent possible inconsistencies if your implementation is coupled to the parsed AST

parseMeta(code, options)

Alias: meta Return: mixed

Parse a given code and return an intermediate resultant object tree structure which includes meta data such as block operators, block expressions, references and attributes prefixed with $$


Alias: run Return: mixed

Process the given AST and return the compilation result.

tokens(code, options)

Alias: parseTokens Return: array

Returns a one-level objects collection with the existent tokens in the given code

load(path, callback)

Context: browser

Performs an asynchronous XHR request and pass to the callback the response body as plain text. It will throw an Error exception if cannot perform the request

oli.load('path/to/file.oli', function (text) {

oli.Compiler(ast, options)

The compiler perform a side-by-side code transformation and generation given an AST tree. It creates a new memory context and uses the tranformer and generator in order to proceed with the compilation

Once you create an instance of the object, you need to call the compile() method in order to perform the compilation

oli.Compiler.transformer(ast, memoryContext)

This method performs an AST traversal walk transforming each node and returning an intermediate-level simplified object tree

oli.Compiler.generator(obj, memoryContext)

Takes the intermediate object from the trasnformation process and performs the final code generator. It takes the responsabilities of the interpreter, data mutation and final code generation


An object with the AST node type transformer functions



Type: boolean Default: false

Return an intermediate level object with metadata properties. This is useful when you need to process an intermediate object that includes tokens, operators, expressions and more, instead of process a cutted resultant object


Type: boolean Default: false


Type: object Default: null

Set of local variables context to be passed to the compilation sandbox


oli.js provides detailed errors. Usually it will be throwed as exception


  • SyntaxError
  • CompileError
  • TypeError
  • ReferenceError


Each error object instance will have the following members

  • message
  • fullMessage
  • line
  • column
  • offset
  • expect (SyntaxError only)
  • found (SyntaxError only)


Wanna help? Cool! It will be really apreciated :)

You must add new test cases for any new feature or refactor you do, always following the same design/code patterns that already exist

Tests specs are completely written in LiveScript language. Take a look to the language documentation if you are new with it. You should follow the LiveScript language conventions defined in the coding style guide


Only node.js and Grunt are required for development

Clone/fork this repository

$ git clone && cd oli-js

Install package dependencies

$ npm install

Run tests

$ npm test

Run benchmarks

grunt bench

Coding zen mode

$ grunt dev [--force]

Cyclomatic complexibility report

$ grunt plato

Browser sources bundle

$ grunt build

Release a new version

$ grunt release


Copyright (c) Tomas Aparicio

Released under the MIT license

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