sunkit02/jlox

JLox

An implementation of the Lox programming language base on Robert Nystrom's book Crafting Interpreters in Java.

Chapters Completed

• Chapter 1
• Chapter 2
• Chapter 3
• Chapter 4
• Chapter 5
• Chapter 6
• Chapter 7
• Chapter 8
• Chapter 9
• Chapter 10
• Chapter 11
• Chapter 12
• Chapter 13
• Chapter 14
• Chapter 15
• Chapter 16
• Chapter 17
• Chapter 18
• Chapter 19
• Chapter 20
• Chapter 21
• Chapter 22
• Chapter 23
• Chapter 24
• Chapter 25
• Chapter 26
• Chapter 27
• Chapter 28
• Chapter 29
• Chapter 30

Grammar of Current Implementation

Expressions

expression  -> literal
             | unary
             | binary
             | grouping ;
             
literal     -> NUMBER | STRING | "true" | "false" | "nil" ;

grouping    -> "(" expression ")" ;

unary       -> ( "-" | "!" ) expression ;

binary      -> expression operator expression ;

operator    -> "==" | "!=" | "<" | "<=" | ">" | ">="
             | "+"  | "-"  | "*" | "/" ;

# For variable access
primary     -> "true" | "false | "nil" 
             | NUMBER | STRING
             | "(" expression ")"
             | IDENTIFIER ;

Statements

program         -> declaration* EOF ;

declaration     -> varDecl
                 | statement ;
                 
varDecl         -> "var" IDENTIFIER ( "=" expression )? ";" ;

statement       -> exprStmt
                 | printStmt
                 | block ;

block           -> "{" declaration* "}" ;
                 
exprStmt        -> expression ";" ;

printStmt       -> "print" expression ";" ;

Lexical Grammar

NUMBER          -> DIGIT+ ( "." DIGIT* )? ;
STRING          -> "\"" <any char except "\"">* "\"" ;
IDENTIFIER      -> ALPHA ( ALPHA | DIGIT )* ;
ALPHA           -> "a" ... "z" | "A" ... "Z" | "_" ;
DIGIT           -> "0" ... "9" ;

Challenges Implemented

• 7.2 Implement implicit type conversion during string concatenation