Javalette compiler

Description of the Javalette language is depicted in the included "Javalette.tex" in ./doc.
Implemented features:

• Parsing
• Typechecking
• LLVM-Backend

Extensions

• Arrays
• Multi-dimensional Arrays

Prerequisites:

• bison (>=3.8.2)
• flex (>=2.6.4)
• bnfc (tested with v2.9.4)
• g++/clang++ with C++17 support
• llvm & llvm-dev packages (available from all pkg-managers)
• python3 (only for testing)

Build instructions: Produces (in root): 'jlc'

make

and to remove build artefacts,

make clean

Usage (from root):

./jlc <input-file.jl>

• If the input arg is invalid, the program will exit with code 1.
• If the input arg is empty, the program will start reading from std in.
• A parser-error will print: "ERROR: Parse error on line x"
• The compiler will then attempt to run the typechecking module, which on failed attempt will print the corresponding error to std err prepended with 'ERROR:' On success, "OK" will be printed to std err.
• If type-checking succeeds, the compiler will compile the program to LLVM IR and stream it to std-out.

Parsing conflicts:

There is just 1 shift/reduce conflict, which is the standard dangling 'else', which is present in other languages like C/Java. The bison parser-generator confirms this and reports it in the logs. Bison as other parser-generators, will choose the shift action which in practice means that the 'else'-statement will be attached to the inner 'if' like so:

if (expr) { if (expr) stmt ; else stmt ;}