Scala Packrat Parser Combinators for DSLs

This is an example packrat parser combinator for a small DSL that parses these two functions:

def foo(a: Int, b: Int, c: Int) : Int = {
  let d = a + b * c;
  let e = a + b + d;
  return e;
}

and

def bar(a: Int, b: Int, c: Int) : Int = {
  let d = a > b and c > a + b;
  return d;
}

It shows

• Example of full lexer and parser using packrat parsers
• Writing lexer using RegexParsers
• Parsing that correctly handles
  • operator precedence (4 example levels)
  • operator associativity
  • generating abstract syntax tree (AST)
• Debugging support for parsing rules

Run

./gradlew run