AnarchoSystems / LRParser

LR Parser lib

LRParser

This library allows you to specify grammars like so:

enum NonLR0Term : Character, Terminal {
    case one = "1"
}

enum NonLR0NTerm : String, NonTerminal {
    case E
}

enum NonLR0 : String, Rules {
    
    case eIsOne
    case oneE
    
    static var goal : NonLR0NTerm {.E}
    
    var rule: Rule<NonLR0Term, NonLR0NTerm> {
        switch self {
        case .eIsOne:
            return Rule(.E, expression: /.one)
        case .oneE:
            return Rule(.E, expression: /.one, /.E)
        }
    }
    
}

// Test


    func testNonLR() {
        XCTAssertThrowsError(try Parser.LR0(rules: NonLR0.self))
        XCTAssertNoThrow(try Parser.CLR1(rules: NonLR0.self))
    }
    
    func testOnes() throws {
        let parser = try Parser.CLR1(rules: NonLR0.self)
        XCTAssertNoThrow(try parser.parse("111111"))
    }
    

One can also specify AST transformations in the rules.

Further Reading

Wiki

Geeks for Geeks

Geeks for Geeks

Geeks for Geeks