interpreter in Java as part of the book Crafting Interpreters

building

run make bin/lox/Lox.class (without Make: javac src/lox/Lox.java -d bin -sourcepath src)

.jar

run make bin/lox.jar

usage

running the REPL

run make run (without Make: java -cp bin lox.Lox)

executing a file

run make run ARGS=<FILENAME>

adding a new AST definition

the AST is generated from a string definition and must be regenerated whenever this string is updated.

1. add new definition under Main, in src/lox/GenerateAst.java
2. run make run-GenerateAst
3. fill in new visitor methods for Interpreter in src/lox/Interpreter.java

TODO:

• increment (PLUSPLUS) unary operator
• parser: add newline token for better error handling, unwinding and synchronizing
• interpreter: cast double to boolean for things like 1 ? a : b;
• interpreter: cast boolean to double for things like (a == b) * 4
• fully implement ternary expressions (cond ? branch1 : branch2)
• parser with global "level" state, or match error production for extra closing bracket (ex.: {}})

ideas

• throw some kind of EndOfExpression exception during parsing so we can skip the upward chain of redundant checks when we know the next token (EOF) won't match anything
• allow identifiers to start with a number - current valid identifier is /[a-zA-Z][a-zA-Z0-9]*/ (cursed)