simon - {Sim}ple {O}bject {N}otation

Simon is a framework that supports implementation of DSLs driven by user-provided metamodels.

Motivation

Imagine there was a conventional way of textually representing object models?

Simon can represent graphs, not only trees

JSON and YAML work fine for object trees. However, object models are more diverse than trees. Simon supports associations between objects.

Simon is polyglot

Simon can be implemented on almost any language.

The first reference implementation happens to be implemented in Java.

Simon's metamodel

You can read more about Simon's metamodel by checking out the documentation generated from the reference implementation (javadoc).

The general syntax for Simon-based programs

Language declaration

Every Simon program starts with a language declaration (@<language-name>).

@language <language-name>
...

Program elements

Every program element is declared by specifying the kind of element, an optional name, and an optional body.

These are all valid Simon programs:

@language UI
application myApplication { }

@language UI
application myApplication

@language UI
application {}

Element properties

Any element of a kind that contains attributes, properties can be specified as:

<kind> [<name>] ([<attribute-name> : <attribute-value>[ ...]])

Example:

button btn1a (label : 'Ok')

Child elements

For any element of a kind that admits child elements, children can be specified like this:

screen screen1 (layout : Vertical) {
    children {
        button btn1a (label : 'Ok')
        button btn1b (
            label : 'Cancel' 
            backgroundColor : #(red : 100 green : 50)
    	)
    	link(label: 'To screen 2') {
    	  targetScreen: screen2
    	}
    }
}

A simple Simon-encoded program

See an example Simon program describing a user-interface:

@language UI
application myApplication { 
  screens { 
    screen screen1 (layout : Vertical) {
        children {
            button btn1a (label : 'Ok')
            button btn1b (
                label : 'Cancel' 
                backgroundColor : #(red : 100 green : 50)
            )
            link(label: 'To screen 2') {
              targetScreen: screen2
            }
        }
    } 
    screen screen2 {
        children {
            button btn2a (label : 'Ok')
        }
    } 
    screen screen3 {} 
  } 
}

Java/Ecore-based implementation

Module structure

• gen-utils - utilities used by Simon but not tied to the Simon API
• metamodel - defines the metamodel behind Simon
• annotation-dsl - an annotation-based DSL for defining a Simon metamodel
• compiler-source - API for compiler sources
• compiler-backend - API for compiler backends
• compiler - the basic API for the Java-based Simon compiler
• parser-antlr - the ANTLR-based generic parser for all Simon-based DSLs
• compiler-antlr - the ANTLR-based generic compiler
• compiler-source-ecore - a source implementation for the Simon compiler which consumes Ecore metamodels
• compiler-backend-ecore - a backend for the Simon compiler which produces EMF-based models
• metamodel-ecore - an implementation of the Simon metamodel on top of Ecore metamodels and pure Java-based metamodels
• example-languages - a playground for languages, including some used in tests
• tests - all tests live here