generator.swift

//
//  main.swift
//  Stacks
//
//  Created by Philippe Hausler on 6/14/17.
//  Copyright © 2017 Philippe Hausler. All rights reserved.
//

import Foundation
import Darwin

func generateEnum(_ count: Int) {
    let preamble = """
enum Stack<T> {
    init() { self = .s0 }

    case s0
"""
    print(preamble)
    for idx in 1..<count {
        let tuple = "(" + repeatElement("T", count: idx).joined(separator: ", ") + ")"
        let generatedCase = "    case s\(idx)\(tuple)\n"
        print(generatedCase, terminator: "")
    }
    let postamble1 = """

    subscript(_ idx: Int) -> T {
        get {
            switch self {
                case .s0: fatalError("Index out of range")
"""
    print(postamble1)
    
    for idx in 1..<count {
        let variables = (0..<idx).map { "let t\($0)" }.joined(separator: ", ")
        let cases = (0..<idx).map { "                    case \($0): return t\($0)"}.joined(separator: "\n")
        let generatedCase = """
                case .s\(idx)(\(variables)):
                    switch idx {
\(cases)
                    default: fatalError("Index out of range")
                    }
"""
        print(generatedCase)
    }
    
    let postamble2 = """
            }
        }
        set {
            switch self {
                case .s0: fatalError("Index out of range")
            case .s1:
                    switch idx {
                    case 0: self = .s1(newValue)

                    default: fatalError("Index out of range")
                    }
"""
    print(postamble2)
    for idx in 2..<count {
        let variables = (0..<idx).map { "let t\($0)" }.joined(separator: ", ")
        let baseAssignments = (0..<idx).map { "t\($0)" }
        var cases = ""
        for caseIdx in 0..<idx {
            var assignments = baseAssignments
            assignments[caseIdx] = "newValue"
            let caseInstance = """
                    case \(caseIdx): self = .s\(idx)(\(assignments.joined(separator: ", ")))

"""
            cases += caseInstance
        }
        let generatedCase = """
                case .s\(idx)(\(variables)):
                    switch idx {
\(cases)
                    default: fatalError("Index out of range")
                    }
"""
        print(generatedCase)
    }
    let postamble3 = """
            }
        }
    }
}
"""
    print(postamble3)
}

generateEnum(32) // creates a valid swift file
// generateEnum(512) // creates an invalid swift file?!