AnyRegexOutputTests.swift

import XCTest
import _StringProcessing
import RegexBuilder

private let enablePrinting = false

// Find and extract potential IDs. IDs are 8 bytes encoded as
// 16 hexadecimal numbers, with an optional `-` between every
// double-byte (i.e. 4 hex digits).
//
// AAAA-BBBB-CCCC-DDDD
// AAAABBBBCCCCDDDD
// AAAABBBBCCCC-DDDD
//
// IDs are converted to uppercase and hyphen separated
//
// The regex can have special capture names which affect replacement
// behavior
//   - "salient": presented uppercase in square brackets after
//   - "note": presented lowercase in parens
//   - none: nothing
//   - no captures: "<error>"
fileprivate let input = """
  Machine 1234-5678-90ab-CDEF connected
  Session FEDCAB0987654321 ended
  Artiface 0011deff-2231-abcd contrived
  """
fileprivate let noCapOutput = """
  Machine <error> connected
  Session <error> ended
  Artiface <error> contrived
  """
fileprivate let unnamedOutput = """
  Machine 1234-5678-90AB-CDEF connected
  Session FEDC-AB09-8765-4321 ended
  Artiface 0011-DEFF-2231-ABCD contrived
  """
fileprivate let salientOutput = """
  Machine 1234-5678-90AB-CDEF [5678] connected
  Session FEDC-AB09-8765-4321 [AB09] ended
  Artiface 0011-DEFF-2231-ABCD [DEFF] contrived
  """
fileprivate let noteOutput = """
  Machine 1234-5678-90AB-CDEF (5678) connected
  Session FEDC-AB09-8765-4321 (ab09) ended
  Artiface 0011-DEFF-2231-ABCD (deff) contrived
  """

fileprivate enum Kind {
  case none
  case unnamed
  case salient
  case note

  func contains(captureNamed s: String) -> Bool {
    switch self {
      case .none:    return false
      case .unnamed: return false
      case .salient: return s == "salient"
      case .note:    return s == "note"
    }
  }

  var expected: String {
    switch self {
    case .none: return noCapOutput
    case .unnamed: return unnamedOutput
    case .salient: return salientOutput
    case .note: return noteOutput
    }
  }
}

fileprivate func checkContains<Output>(
  _ re: Regex<Output>, _ kind: Kind
) {
  for name in ["", "salient", "note", "other"] {
    XCTAssertEqual(
      kind.contains(captureNamed: name), re.contains(captureNamed: name))
  }
}

fileprivate func checkAROReplacing<Output>(
  _ re: Regex<Output>, _ kind: Kind
) {
  let aro = Regex<AnyRegexOutput>(re)
  let output = input.replacing(aro) {
    (match: Regex<AnyRegexOutput>.Match) -> String in

    if match.count < 5 { return "<error>" }

    let suffix: String
    if re.contains(captureNamed: "salient") {
      let body = match["salient"]!.substring?.uppercased() ?? "<no capture>"
      suffix = " [\(body)]"
    } else if re.contains(captureNamed: "note") {
      let body = match["note"]!.substring?.lowercased() ?? "<no capture>"
      suffix = " (\(body))"
    } else {
      suffix = ""
    }

    return match.output.dropFirst().lazy.map {
      $0.substring!.uppercased()
    }.joined(separator: "-") + suffix
  }

  XCTAssertEqual(output, kind.expected)

  if enablePrinting {
    print("---")
    print(output)
    print(kind)
  }
}

fileprivate func check<Output>(
  _ re: Regex<Output>, _ kind: Kind, _ expected: String
) {
  let aro = Regex<AnyRegexOutput>(re)
  let casted = try! XCTUnwrap(Regex(aro, as: Output.self))

  // contains(captureNamed:)
  checkContains(re, kind)
  checkContains(aro, kind)
  checkContains(casted, kind)

  // replacing
  checkAROReplacing(re, kind)
  checkAROReplacing(aro, kind)
  checkAROReplacing(casted, kind)
}

@available(SwiftStdlib 5.7, *)
extension RegexDSLTests {

  func testContrivedAROExample() {
    // Literals (mocked up via explicit `as` types)
    check(try! Regex(#"""
      (?x)
      \p{hexdigit}{4} -? \p{hexdigit}{4} -?
      \p{hexdigit}{4} -? \p{hexdigit}{4}
      """#, as: Substring.self),
      .none,
      noCapOutput
    )

    check(try! Regex(#"""
      (?x)
      (\p{hexdigit}{4}) -? (\p{hexdigit}{4}) -?
      (\p{hexdigit}{4}) -? (\p{hexdigit}{4})
      """#, as: (Substring, Substring, Substring, Substring, Substring).self),
      .unnamed,
      unnamedOutput    
    )
    check(try! Regex(#"""
      (?x)
      (\p{hexdigit}{4}) -? (?<salient>\p{hexdigit}{4}) -?
      (\p{hexdigit}{4}) -? (\p{hexdigit}{4})
      """#, as: (Substring, Substring, salient: Substring, Substring, Substring).self),
      .salient,
      salientOutput
    )
    check(try! Regex(#"""
      (?x)
      (\p{hexdigit}{4}) -? (?<note>\p{hexdigit}{4}) -?
      (\p{hexdigit}{4}) -? (\p{hexdigit}{4})
      """#, as: (Substring, Substring, note: Substring, Substring, Substring).self),
      .note,
      noteOutput
    )

    // Run-time strings (ARO)
    check(try! Regex(#"""
      (?x)
      \p{hexdigit}{4} -? \p{hexdigit}{4} -?
      \p{hexdigit}{4} -? \p{hexdigit}{4}
      """#),
      .none,
      noCapOutput)
    check(try! Regex(#"""
      (?x)
      (\p{hexdigit}{4}) -? (\p{hexdigit}{4}) -?
      (\p{hexdigit}{4}) -? (\p{hexdigit}{4})
      """#),
      .unnamed,
      unnamedOutput
    )
    check(try! Regex(#"""
      (?x)
      (\p{hexdigit}{4}) -? (?<salient>\p{hexdigit}{4}) -?
      (\p{hexdigit}{4}) -? (\p{hexdigit}{4})
      """#),
      .salient,
      salientOutput
    )
    check(try! Regex(#"""
      (?x)
      (\p{hexdigit}{4}) -? (?<note>\p{hexdigit}{4}) -?
      (\p{hexdigit}{4}) -? (\p{hexdigit}{4})
      """#),
      .note,
      noteOutput
    )

    // Run-time strings (errors)
    XCTAssertThrowsError(try Regex("abc", as: (Substring, Substring).self))
    XCTAssertThrowsError(try Regex("(abc)", as: Substring.self))
    XCTAssertThrowsError(try Regex("(?<test>abc)", as: (Substring, Substring).self))
    XCTAssertThrowsError(try Regex("(?<test>abc)?", as: (Substring, test: Substring).self))
    
    XCTAssertNoThrow(try Regex("abc", as: Substring.self))
    XCTAssertNoThrow(try Regex("(abc)", as: (Substring, Substring).self))
    XCTAssertNoThrow(try Regex("(?<test>abc)", as: (Substring, test: Substring).self))
    XCTAssertNoThrow(try Regex("(?<test>abc)?", as: (Substring, test: Substring?).self))
    
    // Builders
    check(
      Regex {
        let doublet = Repeat(.hexDigit, count: 4)
        doublet
        Optionally { "-" }
        doublet
        Optionally { "-" }
        doublet
        Optionally { "-" }
        doublet
      },
      .none,
      noCapOutput
    )
    check(
      Regex {
        let doublet = Repeat(.hexDigit, count: 4)
        Capture { doublet }
        Optionally { "-" }
        Capture { doublet }
        Optionally { "-" }
        Capture { doublet }
        Optionally { "-" }
        Capture { doublet }
      },
      .unnamed,
      unnamedOutput
    )

    // FIXME: `salient` and `note` builders using a semantically rich
    // `mapOutput`

  }
}