JSWithTruffle

JavaScript runtime implementation (partial) in Java using Truffle.

Language description

Application implements subset of Ecmascript, specifically:

• variables - integer, string and boolean types
• if branches
• while loops
• arrays accessible via [] operation
• null, undefined
• console output via console.log()

Application example

Aplication requires GRAAL VM.

1. Build the app using mvn package
2. Run the app ./js bubbleSort.js or ./js fibonaci.js
3. Examine the output in the console

These two applications are pretty familiar to any computer scientist. First called bubbleSort.js performs simple sorting on a given array (using, of course, Bubble Sort algorithm), second one called fibonaci.js counts Fibonaci sequence.

Bubble Sort should output this:

JSArray{list=[3, 9, 34, 198, 200, 203, 746, 764, 984]}

Fibonaci should output this:

1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181 6765 10946 17711 28657 46368 75025 121393 196418 317811 514229

How to run your own code

Insert your javascript file in /src/main/resources/test/, build the app and run it with the correct filename.

Unit tests

Basic unit tests can be found in test folder in file JavascriptTest.java. These test check if all of the implemented Javascript features work (operations, variables of different type, if branches, while loops and arrays). It also runs both testing examples.

Possible future work

Another features which could be (relatively) easily implemented:

• Lexical context for blocks of code (just using already implemented frameDescriptors stack)
• another operations (>= etc.)
• functions (as there is already JSFunction type implemented)
• better array inicialization with multiple values

Sources

Implementation was based on Brainfuck Truffle interpreter and the insights from Writing a Language in Truffle. Part 2: Using Truffle and Graal tutorial were used. Application uses Mozzila Nashorn as a JavaScript parser.