gojo

Go javascript engine-o.

go run main.go

Use environment variables to configure the engine.

• GOJO_INPUT_FILE - Set file path to use it as input (default=input_program.js).
• GOJO_VERBOSE - Set to true to enable verbose logging.
• GOJO_MEGA_VERBOSE - Set to true to enable EVEN MORE logging.
• GOJO_REPL_MODE - Set to true to enable REPL mode.

Tests

To run lexer, parser and interpreter tests:

go test ./...

Checkpoints

Yo! This is a for fun project and not intended to ever be finished. o7

The goal is to have a resonably fast and correct javascript engine for the core features of the language only.

Checkout the TODO.md.

Parts by example:

For the code var x = 1 + 1;

1. Lexer (FSM): Produces a stream of tokens var, x, =, 1, +, 1, ;
2. Parser (Recursive Descent): Produces an AST Program -> Statements[] -> VariableDeclaration(x = BinaryExpression(1 + 1))
3. Interpreter (Go Runtime): Process the AST and stores the value in the environment x = 2

References

• ECMAScript spec - https://tc39.es/ecma262/
• JSConf rust JS engine talk - https://youtu.be/_uD2pijcSi4
• Writing a tokenizer (not great performance wise but a start) - https://dev.to/ndesmic/writing-a-tokenizer-1j85
• General simple lexer - https://codemaster138.github.io/blog/creating-an-interpreter-part-1-lexer/
• Writing an interpreter in go - https://edu.anarcho-copy.org/Programming%20Languages/Go/writing%20an%20INTERPRETER%20in%20go.pdf
• Acorn js js parser - https://github.com/acornjs/acorn
• Standard compliant parser - https://github.com/jquery/esprima
• AST Explore - https://astexplorer.net/
• Recursive Descent Parsing: https://www.cs.rochester.edu/u/nelson/courses/csc_173/grammars/parsing.html#:~:text=Recursive-descent%20parsing%20is%20one,non-terminal%20with%20a%20procedure
• Goja: https://github.com/dop251/goja (great minds think alike)