//===--- StdlibUnittest.swift.gyb -----------------------------*- swift -*-===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2015 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See http://swift.org/LICENSE.txt for license information
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

import SwiftPrivate
import SwiftPrivatePthreadExtras
import SwiftPrivateDarwinExtras

#if os(OSX) || os(iOS) || os(watchOS) || os(tvOS)
import Darwin
#elseif os(Linux)
import Glibc
#endif

#if _runtime(_ObjC)
import ObjectiveC
#endif

public struct SourceLoc {
  public let file: String
  public let line: UWord
  public let comment: String?

  public init(_ file: String, _ line: UWord, comment: String? = nil) {
    self.file = file
    self.line = line
    self.comment = comment
  }

  public func withCurrentLoc(
      file: String = __FILE__, line: UWord = __LINE__
  ) -> SourceLocStack {
    return SourceLocStack(self).with(SourceLoc(file, line))
  }
}

public struct SourceLocStack {
  let locs: _UnitTestArray<SourceLoc>

  public init() {
    locs = []
  }

  public init(_ loc: SourceLoc) {
    locs = [ loc ]
  }

  init(_locs: _UnitTestArray<SourceLoc>) {
    locs = _locs
  }

  var isEmpty: Bool {
    return locs.isEmpty
  }

  public func with(loc: SourceLoc) -> SourceLocStack {
    var locs = self.locs
    locs.append(loc)
    return SourceLocStack(_locs: locs)
  }

  public func withCurrentLoc(
      file: String = __FILE__, line: UWord = __LINE__
  ) -> SourceLocStack {
    return with(SourceLoc(file, line))
  }
}

func _printStackTrace(stackTrace: SourceLocStack?) {
  guard let s = stackTrace else { return }
  println("stacktrace:")
  for i in 0..<s.locs.count() {
    let loc = s.locs[s.locs.count() - i - 1]
    let comment = (loc.comment != nil) ? " ; \(loc.comment!)" : ""
    println("  #\(i): \(loc.file):\(loc.line)\(comment)")
  }
}

// FIXME: these variables should be atomic, since multiple threads can call
// `expect*()` functions.
var _anyExpectFailed = false
var _seenExpectCrash = false

public func expectEqual<T : Equatable>(
    expected: T, _ actual: T,
    stackTrace: SourceLocStack? = nil,
    file: String = __FILE__, line: UWord = __LINE__,
    collectMoreInfo: (()->String)? = nil
) {
  expectEqual(expected, actual, {$0 == $1},
    stackTrace: stackTrace, file: file, line: line,
    collectMoreInfo: collectMoreInfo)
}

public func expectEqual<T : Equatable, U : Equatable>(
  expected: (T, U), _ actual: (T, U),
  stackTrace: SourceLocStack? = nil,
  file: String = __FILE__, line: UWord = __LINE__,
  collectMoreInfo: (()->String)? = nil
) {
  expectEqual(expected.0, actual.0, {$0 == $1},
    stackTrace: stackTrace, file: file, line: line,
    collectMoreInfo: collectMoreInfo)
  expectEqual(expected.1, actual.1, {$0 == $1},
    stackTrace: stackTrace, file: file, line: line,
    collectMoreInfo: collectMoreInfo)
}

public func expectEqual<T>(
    expected: T, _ actual: T, _ equal: (T,T)->Bool,
    stackTrace: SourceLocStack? = nil,
    file: String = __FILE__, line: UWord = __LINE__,
    collectMoreInfo: (()->String)? = nil
) {
  if !equal(expected, actual) {
    _anyExpectFailed = true
    println("check failed at \(file), line \(line)")
    _printStackTrace(stackTrace)
    println("expected: \"\(expected)\" (of type \(_stdlib_getDemangledTypeName(expected)))")
    println("actual: \"\(actual)\" (of type \(_stdlib_getDemangledTypeName(expected)))")
    if collectMoreInfo != nil { println(collectMoreInfo!()) }
    println()
  }
}

public func expectNotEqual<T : Equatable>(
    expected: T, _ actual: T,
    stackTrace: SourceLocStack? = nil,
    file: String = __FILE__, line: UWord = __LINE__,
    collectMoreInfo: (()->String)? = nil
) {
  if expected == actual {
    _anyExpectFailed = true
    println("check failed at \(file), line \(line)")
    _printStackTrace(stackTrace)
    println("unexpected value: \"\(actual)\" (of type \(_stdlib_getDemangledTypeName(actual)))")
    if collectMoreInfo != nil { println(collectMoreInfo!()) }
    println()
  }
}

// Can not write a sane set of overloads using generics because of:
// <rdar://problem/17015923> Array->NSArray implicit conversion insanity
public func expectOptionalEqual<T : Equatable>(
    expected: T, _ actual: T?,
    stackTrace: SourceLocStack? = nil,
    file: String = __FILE__, line: UWord = __LINE__
) {
  if (actual == nil) || expected != actual! {
    _anyExpectFailed = true
    println("check failed at \(file), line \(line)")
    _printStackTrace(stackTrace)
    println("expected: \"\(expected)\" (of type \(_stdlib_getDemangledTypeName(expected)))")
    println("actual: \"\(actual)\" (of type \(_stdlib_getDemangledTypeName(actual)))")
    println()
  }
}

public func expectEqual<T : Equatable>(
    expected: T?, _ actual: T?,
    stackTrace: SourceLocStack? = nil,
    file: String = __FILE__, line: UWord = __LINE__
) {
  if (actual == nil) != (expected == nil)
    || actual != nil && expected! != actual! {
    _anyExpectFailed = true
    println("check failed at \(file), line \(line)")
    _printStackTrace(stackTrace)
    println("expected: \"\(expected)\" (of type \(_stdlib_getDemangledTypeName(expected)))")
    println("actual: \"\(actual)\" (of type \(_stdlib_getDemangledTypeName(actual)))")
    println()
  }
}

// Array<T> is not Equatable if T is.  Provide additional overloads.
// Same for Dictionary.
%for (Generic, EquatableType) in [
%    ('<T : Equatable>', 'ContiguousArray<T>'),
%    ('<T : Equatable>', '_UnitTestArray<T>'),
%    ('<T : Equatable>', 'ArraySlice<T>'),
%    ('<T : Equatable>', 'Array<T>'),
%    ('<T, U : Equatable>', 'Dictionary<T, U>')]:

public func expectEqual${Generic}(
    expected: ${EquatableType}, _ actual: ${EquatableType},
    stackTrace: SourceLocStack? = nil,
    file: String = __FILE__, line: UWord = __LINE__,
    collectMoreInfo: (()->String)? = nil
) {
  expectEqual(
    expected, actual,
    // FIXME: Simpler closures don't work here due to
    // <rdar://problem/17716712> and <rdar://problem/17717618>
    { (x: ${EquatableType}, y: ${EquatableType})->Bool in  x == y },
    stackTrace: stackTrace, file: file, line: line,
    collectMoreInfo: collectMoreInfo)
}


public func expectEqualSequence${Generic}(
    expected: ${EquatableType}, _ actual: ${EquatableType},
    stackTrace: SourceLocStack? = nil,
    file: String = __FILE__, line: UWord = __LINE__,
    collectMoreInfo: (()->String)? = nil
) {
  expectEqual(
    expected, actual,
    // FIXME: Simpler closures don't work here due to
    // <rdar://problem/17716712> and <rdar://problem/17717618>
    { (x: ${EquatableType}, y: ${EquatableType})->Bool in  x == y },
    stackTrace: stackTrace, file: file, line: line, 
    collectMoreInfo: collectMoreInfo)
}


func _expectNotEqual${Generic}(
    expected: ${EquatableType}, actual: ${EquatableType},
    file: String = __FILE__, line: UWord = __LINE__,
    collectMoreInfo: (()->String)? = nil
) {
  if expected == actual {
    _anyExpectFailed = true
    println("check failed at \(file), line \(line)")
    println("unexpected value: \"\(actual)\" (of type \(_stdlib_getDemangledTypeName(actual)))")
    if collectMoreInfo != nil { println(collectMoreInfo!()) }
    println()
  }
}

public func expectOptionalEqual${Generic}(
    expected: ${EquatableType}, _ actual: ${EquatableType}?,
    file: String = __FILE__, line: UWord = __LINE__
) {
  if (actual == nil) || expected != actual! {
    _anyExpectFailed = true
    println("check failed at \(file), line \(line)")
    println("expected: \"\(expected)\" (of type \(_stdlib_getDemangledTypeName(expected)))")
    println("actual: \"\(actual)\" (of type \(_stdlib_getDemangledTypeName(actual)))")
    println()
  }
}

%end

%for ComparableType in ['Int']:

public func expectLT(
  expected: ${ComparableType}, _ actual: ${ComparableType},
  stackTrace: SourceLocStack? = nil,
  file: String = __FILE__, line: UWord = __LINE__,
  collectMoreInfo: (()->String)? = nil
) {
  if !(expected < actual) {
    _anyExpectFailed = true
    println("check failed at \(file), line \(line)")
    _printStackTrace(stackTrace)
    println("expected: \"\(expected)\"")
    println("actual: \"\(actual)\"")
    if collectMoreInfo != nil { println(collectMoreInfo!()) }
    println()
  }
}

public func expectLE(
  expected: ${ComparableType}, _ actual: ${ComparableType},
  stackTrace: SourceLocStack? = nil,
  file: String = __FILE__, line: UWord = __LINE__,
  collectMoreInfo: (()->String)? = nil
) {
  if !(expected <= actual) {
    _anyExpectFailed = true
    println("check failed at \(file), line \(line)")
    _printStackTrace(stackTrace)
    println("expected: \"\(expected)\"")
    println("actual: \"\(actual)\"")
    if collectMoreInfo != nil { println(collectMoreInfo!()) }
    println()
  }
}

public func expectGE(
  expected: ${ComparableType}, _ actual: ${ComparableType},
  stackTrace: SourceLocStack? = nil,
  file: String = __FILE__, line: UWord = __LINE__,
  collectMoreInfo: (()->String)? = nil
) {
  if !(expected >= actual) {
    _anyExpectFailed = true
    println("check failed at \(file), line \(line)")
    _printStackTrace(stackTrace)
    println("expected: \"\(expected)\"")
    println("actual: \"\(actual)\"")
    if collectMoreInfo != nil { println(collectMoreInfo!()) }
    println()
  }
}

%end

public func expectType<T>(_: T.Type, inout _ x: T) {}

public func isSequenceType<X : SequenceType>(x: X) -> X { return x }
public func expectIsBooleanType<X : BooleanType>(inout x: X) -> X { return x }

public struct AssertionResult : CustomStringConvertible, BooleanType {
  init(isPass: Bool) {
    self._isPass = isPass
  }

  public var boolValue: Bool {
    return _isPass
  }

  public func withDescription(description: String) -> AssertionResult {
    var result = self
    result.description += description
    return result
  }

  let _isPass: Bool

  public var description: String = ""
}

public func assertionSuccess() -> AssertionResult {
  return AssertionResult(isPass: true)
}

public func assertionFailure() -> AssertionResult {
  return AssertionResult(isPass: false)
}

public func expectUnreachable(
  stackTrace: SourceLocStack? = nil,
  file: String = __FILE__, line: UWord = __LINE__,
  collectMoreInfo: (()->String)? = nil
) {
  _anyExpectFailed = true
  println("check failed at \(file), line \(line)")
  _printStackTrace(stackTrace)
  println("this code should not be executed")
  if collectMoreInfo != nil { println(collectMoreInfo!()) }
  println()
}

public func expectUnreachableCatch(
  error: _ErrorType,
  stackTrace: SourceLocStack? = nil,
  file: String = __FILE__, line: UWord = __LINE__,
  collectMoreInfo: (()->String)? = nil
) {
  _anyExpectFailed = true
  println("check failed at \(file), line \(line)")
  _printStackTrace(stackTrace)
  println("error should not be thrown: \"\(error)\"")
  if collectMoreInfo != nil { println(collectMoreInfo!()) }
  println()
}

%for BoolType in ['Bool', 'AssertionResult']:

public func expectTrue(
    actual: ${BoolType},
    stackTrace: SourceLocStack? = nil,
    file: String = __FILE__, line: UWord = __LINE__,
    collectMoreInfo: (()->String)? = nil
) {
  if !actual {
    _anyExpectFailed = true
    println("check failed at \(file), line \(line)")
    _printStackTrace(stackTrace)
    println("expected: true")
    println("actual: \(actual)")
    if collectMoreInfo != nil { println(collectMoreInfo!()) }
    println()
  }
}

public func expectFalse(
    actual: ${BoolType},
    stackTrace: SourceLocStack? = nil,
    file: String = __FILE__, line: UWord = __LINE__,
    collectMoreInfo: (()->String)? = nil
) {
  if actual {
    _anyExpectFailed = true
    println("check failed at \(file), line \(line)")
    _printStackTrace(stackTrace)
    println("expected: false")
    println("actual: \(actual)")
    if collectMoreInfo != nil { println(collectMoreInfo!()) }
    println()
  }
}

%end

public func expectEmpty<T>(
    value: Optional<T>,
    stackTrace: SourceLocStack? = nil,
    file: String = __FILE__, line: UWord = __LINE__,
    collectMoreInfo: (()->String)? = nil
) {
  if value != nil {
    _anyExpectFailed = true
    println("check failed at \(file), line \(line)")
    _printStackTrace(stackTrace)
    println("expected optional to be empty")
    println("actual: \"\(value)\"")
    if collectMoreInfo != nil { println(collectMoreInfo!()) }
    println()
  }
}

public func expectNotEmpty<T>(
    value: Optional<T>,
    file: String = __FILE__, line: UWord = __LINE__
) -> T? {
  if value == nil {
    _anyExpectFailed = true
    println("check failed at \(file), line \(line)")
    println("expected optional to be non-empty")
    println()
  }
  return value
}

public func expectCrashLater() {
  println("\(_stdlibUnittestStreamPrefix);expectCrash;\(_anyExpectFailed)")

  var stderr = _Stderr()
  println("\(_stdlibUnittestStreamPrefix);expectCrash", &stderr)

  _seenExpectCrash = true
}

func _defaultTestSuiteFailedCallback() {
  abort()
}

var _testSuiteFailedCallback: () -> () = _defaultTestSuiteFailedCallback

public func _setTestSuiteFailedCallback(callback: () -> ()) {
  _testSuiteFailedCallback = callback
}

extension ProcessTerminationStatus {
  var isSwiftTrap: Bool {
    switch self {
    case .Exit(var status):
      return false
    case .Signal(var signal):
      return CInt(signal) == SIGILL || CInt(signal) == SIGTRAP
    }
  }
}

func _stdlib_getline() -> String? {
  var result = _UnitTestArray<UInt8>()
  while true {
    let c = getchar()
    if c == EOF {
      if result.isEmpty {
        return nil
      }
      return String._fromWellFormedCodeUnitSequence(UTF8.self, input: result)
    }
    if c == CInt(UnicodeScalar("\n").value) {
      return String._fromWellFormedCodeUnitSequence(UTF8.self, input: result)
    }
    result.append(UInt8(c))
  }
}

func _printDebuggingAdvice(fullTestName: String) {
  println("To debug, run:")
  println("$ \(Process.arguments[0]) " +
    "--stdlib-unittest-in-process --stdlib-unittest-filter \"\(fullTestName)\"")
}

var _allTestSuites: _UnitTestArray<TestSuite> = []
var _testSuiteNameToIndex: [String : Int] = [:]

let _stdlibUnittestStreamPrefix = "__STDLIB_UNITTEST__"

@asmname("swift_stdlib_installTrapInterceptor")
func _stdlib_installTrapInterceptor()

func _childProcess() {
  _stdlib_installTrapInterceptor()
  while let line = _stdlib_getline() {
    let parts = line._split(";")
    let testSuiteName = parts[0]
    let testName = parts[1]

    let testSuite = _allTestSuites[_testSuiteNameToIndex[testSuiteName]!]
    _anyExpectFailed = false
    testSuite._runTest(testName)

    println("\(_stdlibUnittestStreamPrefix);end;\(_anyExpectFailed)")

    var stderr = _Stderr()
    println("\(_stdlibUnittestStreamPrefix);end", &stderr)

    if !testSuite._testByName(testName).canReuseChildProcessAfterTest {
      return
    }
  }
}

struct _ParentProcess {
  internal var _pid: pid_t = -1
  internal var _childStdin: _FDOutputStream = _FDOutputStream(fd: -1)
  internal var _childStdout: _FDInputStream = _FDInputStream(fd: -1)
  internal var _childStderr: _FDInputStream = _FDInputStream(fd: -1)

  internal var _runTestsInProcess: Bool
  internal var _filter: String?

  init(runTestsInProcess: Bool, filter: String?) {
    self._runTestsInProcess = runTestsInProcess
    self._filter = filter
  }

  mutating func _spawnChild() {
    let (pid, childStdinFD, childStdoutFD, childStderrFD) =
      spawnChild([ "--stdlib-unittest-run-child" ])
    _pid = pid
    _childStdin = _FDOutputStream(fd: childStdinFD)
    _childStdout = _FDInputStream(fd: childStdoutFD)
    _childStderr = _FDInputStream(fd: childStderrFD)
  }

  mutating func _waitForChild() -> ProcessTerminationStatus {
    let status = posixWaitpid(_pid)
    _pid = -1
    _childStdin.close()
    _childStdout.close()
    _childStderr.close()
    _childStdin = _FDOutputStream(fd: -1)
    _childStdout = _FDInputStream(fd: -1)
    _childStderr = _FDInputStream(fd: -1)
    return status
  }

  /// Returns the values of the corresponding variables in the child process.
  mutating func _runTestInChild(testSuite: TestSuite, _ testName: String)
    -> (anyExpectFailed: Bool, seenExpectCrash: Bool,
        status: ProcessTerminationStatus?,
        crashStdout: _UnitTestArray<String>, crashStderr: _UnitTestArray<String>) {
    if _pid <= 0 {
      _spawnChild()
    }

    println("\(testSuite.name);\(testName)", &_childStdin)

    let currentTest = testSuite._testByName(testName)
    if let stdinText = currentTest.stdinText {
      print(stdinText, &_childStdin)
    }
    if currentTest.stdinEndsWithEOF {
      _childStdin.close()
    }

    var readfds = _stdlib_fd_set()
    var writefds = _stdlib_fd_set()
    var errorfds = _stdlib_fd_set()
    var stdoutSeenCrashDelimiter = false
    var stderrSeenCrashDelimiter = false
    var stdoutEnd = false
    var stderrEnd = false
    var capturedCrashStdout = _UnitTestArray<String>()
    var capturedCrashStderr = _UnitTestArray<String>()
    var anyExpectFailedInChild = false
    while !((_childStdout.isEOF && _childStderr.isEOF) ||
      (stdoutEnd && stderrEnd)) {

      readfds.zero()
      errorfds.zero()
      if !_childStdout.isEOF {
        readfds.set(_childStdout.fd)
        errorfds.set(_childStdout.fd)
      }
      if !_childStderr.isEOF {
        readfds.set(_childStderr.fd)
        errorfds.set(_childStderr.fd)
      }
      var ret: CInt
      repeat {
        ret = _stdlib_select(&readfds, &writefds, &errorfds, nil)
      } while ret == -1  &&  errno == EINTR
      if ret <= 0 {
        fatalError("select() returned an error")
      }
      if readfds.isset(_childStdout.fd) || errorfds.isset(_childStdout.fd) {
        _childStdout.read()
        while var line = _childStdout.getline() {
          if let index = findSubstring(line, _stdlibUnittestStreamPrefix) {
            let controlMessage = line[index..<line.endIndex]._split(";")
            switch controlMessage[1] {
            case "expectCrash":
              stdoutSeenCrashDelimiter = true
              anyExpectFailedInChild = controlMessage[2] == "true"
            case "end":
              stdoutEnd = true
              anyExpectFailedInChild = controlMessage[2] == "true"
            default:
              fatalError("unexpected message")
            }
            line = line[line.startIndex..<index]
            if line.isEmpty {
              continue
            }
          }
          if stdoutSeenCrashDelimiter {
            capturedCrashStdout.append(line)
          }
          println("out>>> \(line)")
        }
        continue
      }
      if readfds.isset(_childStderr.fd) || errorfds.isset(_childStderr.fd) {
        _childStderr.read()
        while var line = _childStderr.getline() {
          if let index = findSubstring(line, _stdlibUnittestStreamPrefix) {
            let controlMessage = line[index..<line.endIndex]._split(";")
            switch controlMessage[1] {
            case "expectCrash":
              stderrSeenCrashDelimiter = true
            case "end":
              stderrEnd = true
            default:
              fatalError("unexpected message")
            }
            line = line[line.startIndex..<index]
            if line.isEmpty {
              continue
            }
          }
          if stderrSeenCrashDelimiter {
            capturedCrashStderr.append(line)
          }
          println("err>>> \(line)")
        }
        continue
      }
    }

    // Check if the child has sent us "end" markers for the current test.
    if stdoutEnd && stderrEnd {
      testSuite._testByName(testName)
      var status: ProcessTerminationStatus? = nil
      if !testSuite._testByName(testName).canReuseChildProcessAfterTest {
        status = _waitForChild()
        switch status! {
        case .Exit(0):
          status = nil
        default:
          ()
        }
      }
      return (
        anyExpectFailedInChild,
        stdoutSeenCrashDelimiter || stderrSeenCrashDelimiter, status,
        capturedCrashStdout, capturedCrashStderr)
    }

    // We reached EOF on stdout and stderr and we did not see "end" markers, so
    // it looks like child crashed (of course it could have closed the file
    // descriptors, but we assume it did not, since it prevent further
    // communication with the parent).
    let status = _waitForChild()
    return (
      anyExpectFailedInChild,
      stdoutSeenCrashDelimiter || stderrSeenCrashDelimiter, status,
      capturedCrashStdout, capturedCrashStderr)
  }

  mutating func run() {
    if let filter = _filter {
      println("StdlibUnittest: using filter: \(filter)")
    }
    for testSuite in _allTestSuites {
      var uxpassedTests = _UnitTestArray<String>()
      var failedTests = _UnitTestArray<String>()
      var skippedTests = _UnitTestArray<String>()
      for t in testSuite._tests {
        let fullTestName = "\(testSuite.name).\(t.name)"
        if let filter = _filter where findSubstring(fullTestName, filter) == nil {
          continue
        }

        let activeSkips = t.getActiveSkipPredicates()
        if !activeSkips.isEmpty {
          skippedTests += [ t.name ]
          println("[ SKIP     ] \(fullTestName) (skip: \(activeSkips))")
          continue
        }

        let activeXFails = t.getActiveXFailPredicates()
        let expectXFail = !activeXFails.isEmpty
        let activeXFailsText = expectXFail ? " (XFAIL: \(activeXFails))" : ""
        println("[ RUN      ] \(fullTestName)\(activeXFailsText)")

        var expectCrash = false
        var childTerminationStatus: ProcessTerminationStatus? = nil
        var crashStdout = _UnitTestArray<String>()
        var crashStderr = _UnitTestArray<String>()
        if _runTestsInProcess {
          if t.stdinText != nil {
            println("The test \(fullTestName) requires stdin input and can't be run in-process, marking as failed")
            _anyExpectFailed = true
          } else {
            _anyExpectFailed = false
            testSuite._runTest(t.name)
          }
        } else {
          (_anyExpectFailed, expectCrash, childTerminationStatus, crashStdout,
           crashStderr) =
            _runTestInChild(testSuite, t.name)
        }

        // Determine if the test passed, not taking XFAILs into account.
        var testPassed = false
        var testFailureExplanation = ""
        switch (_anyExpectFailed, childTerminationStatus, expectCrash) {
        case (_, .None, false):
          testPassed = !_anyExpectFailed

        case (_, .None, true):
          testPassed = false
          testFailureExplanation = "expecting a crash, but the test did not crash"

        case (_, .Some(let status), false):
          testPassed = false
          testFailureExplanation = "the test crashed unexpectedly"

        case (_, .Some(let status), true):
          testPassed = !_anyExpectFailed
        }
        if testPassed && t.crashOutputMatches.count() > 0 {
          // If we still think that the test passed, check if the crash
          // output matches our expectations.
          let crashOutput = crashStdout + crashStderr
          for expectedCrashOutput in t.crashOutputMatches {
            var found = false
            for s in crashOutput {
              if findSubstring(s, expectedCrashOutput) != nil {
                found = true
                break
              }
            }
            if !found {
              println("did not find expected string after crash: \(expectedCrashOutput.debugDescription)")
              testPassed = false
            }
          }
        }

        // Apply XFAILs.
        switch (testPassed, expectXFail) {
        case (true, false):
          println("[       OK ] \(fullTestName)")

        case (true, true):
          uxpassedTests += [ t.name ]
          println("[   UXPASS ] \(fullTestName)")

        case (false, false):
          failedTests += [ t.name ]
          println("[     FAIL ] \(fullTestName)")

        case (false, true):
          println("[    XFAIL ] \(fullTestName)")
        }
      }

      if !uxpassedTests.isEmpty || !failedTests.isEmpty {
        println("\(testSuite.name): Some tests failed, aborting")
        println("UXPASS: \(uxpassedTests)")
        println("FAIL: \(failedTests)")
        println("SKIP: \(skippedTests)")
        if !uxpassedTests.isEmpty {
          _printDebuggingAdvice(uxpassedTests[0])
        }
        if !failedTests.isEmpty {
          _printDebuggingAdvice(failedTests[0])
        }
        _testSuiteFailedCallback()
      } else {
        println("\(testSuite.name): All tests passed")
      }
    }
  }
}

public func runAllTests() {
  struct PersistentState {
    static var runAllTestsWasCalled: Bool = false
  }

  if PersistentState.runAllTestsWasCalled {
    println("runAllTests() called twice.  It is not allowed, aborting.")
    _testSuiteFailedCallback()
    return
  }
  PersistentState.runAllTestsWasCalled = true

#if _runtime(ObjC)
  autoreleasepool {
    _stdlib_initializeReturnAutoreleased()
  }
#endif

  let _isChildProcess: Bool =
    Process.arguments.contains("--stdlib-unittest-run-child")

  if _isChildProcess {
    _childProcess()
  } else {
    var runTestsInProcess: Bool = false
    var filter: String? = nil
    for var i = 0; i < Process.arguments.count(); {
      let arg = Process.arguments[i]
      if arg == "--stdlib-unittest-in-process" {
        runTestsInProcess = true
        ++i
        continue
      }
      if arg == "--stdlib-unittest-filter" {
        filter = Process.arguments[i + 1]
        i += 2
        continue
      }
      if arg == "--help" {
        println(
"optional arguments:\n" +
"--stdlib-unittest-in-process\n" +
"                        run tests in-process without intercepting crashes.\n" +
"                        Useful for running under a debugger.\n" +
"--stdlib-unittest-filter FILTER-STRING\n" +
"                        only run tests whose names contain FILTER-STRING as\n" +
"                        a substring.")
        return
      }

      // FIXME: skipping unrecognized parameters.
      ++i
    }

    var parent = _ParentProcess(
      runTestsInProcess: runTestsInProcess, filter: filter)
    parent.run()
  }
}

public class TestSuite {
  public init(_ name: String) {
    self.name = name
    _precondition(
      _testNameToIndex[name] == nil,
      "test suite with the same name already exists")
    _allTestSuites.append(self)
    _testSuiteNameToIndex[name] = _allTestSuites.count() - 1
  }

  public func test(name: String, _ testFunction: () -> ()) {
    _TestBuilder(testSuite: self, name: name).code(testFunction)
  }

  public func test(name: String) -> _TestBuilder {
    return _TestBuilder(testSuite: self, name: name)
  }

  public func setUp(code: () -> ()) {
    _precondition(_testSetUpCode == nil, "set-up code already set")
    _testSetUpCode = code
  }

  public func tearDown(code: () -> ()) {
    _precondition(_testTearDownCode == nil, "tear-down code already set")
    _testTearDownCode = code
  }

  func _runTest(testName: String) {
    if let f = _testSetUpCode {
      f()
    }
    _testByName(testName).code()
    if let f = _testTearDownCode {
      f()
    }
  }

  func _testByName(testName: String) -> _Test {
    return _tests[_testNameToIndex[testName]!]
  }

  struct _Test {
    let name: String
    let xfail: _UnitTestArray<TestRunPredicate>
    let skip: _UnitTestArray<TestRunPredicate>
    let stdinText: String?
    let stdinEndsWithEOF: Bool
    let crashOutputMatches: [String]
    let code: () -> ()

    /// Whether the test harness should stop reusing the child process after
    /// running this test.
    var canReuseChildProcessAfterTest: Bool {
      return stdinText == nil
    }

    func getActiveXFailPredicates() -> _UnitTestArray<TestRunPredicate> {
      return xfail.filter { $0.evaluate() }
    }

    func getActiveSkipPredicates() -> _UnitTestArray<TestRunPredicate> {
      return skip.filter { $0.evaluate() }
    }
  }

  public struct _TestBuilder {
    let _testSuite: TestSuite
    var _name: String
    var _data: _Data = _Data()

    class _Data {
      var _xfail: _UnitTestArray<TestRunPredicate> = []
      var _skip: _UnitTestArray<TestRunPredicate> = []
      var _stdinText: String? = nil
      var _stdinEndsWithEOF: Bool = false
      var _crashOutputMatches: [String] = []
    }

    init(testSuite: TestSuite, name: String) {
      _testSuite = testSuite
      _name = name
    }

    public func xfail(predicate: TestRunPredicate) -> _TestBuilder {
      _data._xfail.append(predicate)
      return self
    }

    public func skip(predicate: TestRunPredicate) -> _TestBuilder {
      _data._skip.append(predicate)
      return self
    }

    public func stdin(stdinText: String, eof: Bool = false) -> _TestBuilder {
      _data._stdinText = stdinText
      _data._stdinEndsWithEOF = eof
      return self
    }

    public func crashOutputMatches(string: String) -> _TestBuilder {
      _data._crashOutputMatches.append(string)
      return self
    }

    public func code(testFunction: () -> ()) {
      _testSuite._tests.append(_Test(
        name: _name, xfail: _data._xfail, skip: _data._skip,
        stdinText: _data._stdinText,
        stdinEndsWithEOF: _data._stdinEndsWithEOF,
        crashOutputMatches: _data._crashOutputMatches, code: testFunction))
      _testSuite._testNameToIndex[_name] = _testSuite._tests.count() - 1
    }
  }

  var name: String
  var _tests: _UnitTestArray<_Test> = []

  /// Code that is run before every test.
  var _testSetUpCode: (() -> ())?

  /// Code that is run after every test.
  var _testTearDownCode: (() -> ())?

  /// Maps test name to index in `_tests`.
  var _testNameToIndex: [String : Int] = [:]
}

#if os(OSX) || os(iOS) || os(watchOS) || os(tvOS)
@asmname("swift_stdlib_getSystemVersionPlistProperty")
func _stdlib_getSystemVersionPlistPropertyImpl(
  propertyName: UnsafePointer<CChar>) -> UnsafePointer<CChar>

func _stdlib_getSystemVersionPlistProperty(propertyName: String) -> String? {
  return String.fromCString(
    _stdlib_getSystemVersionPlistPropertyImpl(propertyName))
}
#endif

public enum OSVersion : CustomStringConvertible {
  case OSX(major: Int, minor: Int, bugFix: Int)
  case iOS(major: Int, minor: Int, bugFix: Int)
  case iOSSimulator
  case Linux

  public var description: String {
    switch self {
    case OSX(var major, var minor, var bugFix):
      return "OS X \(major).\(minor).\(bugFix)"
    case iOS(var major, var minor, var bugFix):
      return "iOS \(major).\(minor).\(bugFix)"
    case iOSSimulator:
      return "iOSSimulator"
    case Linux:
      return "Linux"
    }
  }
}

func _parseDottedVersion(s: String) -> _UnitTestArray<Int> {
  return _UnitTestArray(lazy(s._split(".")).map { Int($0)! })
}

public func _parseDottedVersionTriple(s: String) -> (Int, Int, Int) {
  var array = _parseDottedVersion(s)
  if array.count() >= 4 {
    fatalError("unexpected version")
  }
  return (
    array.count() >= 1 ? array[0] : 0,
    array.count() >= 2 ? array[1] : 0,
    array.count() >= 3 ? array[2] : 0)
}

func _getOSVersion() -> OSVersion {
#if os(iOS) && (arch(i386) || arch(x86_64))
  // On simulator, the plist file that we try to read turns out to be host's
  // plist file, which indicates OS X.
  //
  // FIXME: how to get the simulator version *without* UIKit?
  return .iOSSimulator
#elseif os(Linux)
  return .Linux
#else
  let productName = _stdlib_getSystemVersionPlistProperty("ProductName")!
  let productVersion = _stdlib_getSystemVersionPlistProperty("ProductVersion")!
  let (major, minor, bugFix) = _parseDottedVersionTriple(productVersion)
  switch productName {
  case "Mac OS X":
    return .OSX(major: major, minor: minor, bugFix: bugFix)
  case "iPhone OS":
    return .iOS(major: major, minor: minor, bugFix: bugFix)
  default:
    fatalError("could not determine OS version")
  }
#endif
}

var _runningOSVersion: OSVersion = _getOSVersion()
var _overrideOSVersion: OSVersion? = nil

/// Override the OS version for testing.
public func _setOverrideOSVersion(v: OSVersion) {
  _overrideOSVersion = v
}

func _getRunningOSVersion() -> OSVersion {
  // Allow overriding the OS version for testing.
  return _overrideOSVersion ?? _runningOSVersion
}

public enum TestRunPredicate : CustomStringConvertible {
  case Custom(() -> Bool, reason: String)

  case OSXAny(/*reason:*/ String)
  case OSXMajor(Int, reason: String)
  case OSXMinor(Int, Int, reason: String)
  case OSXMinorRange(Int, Range<Int>, reason: String)
  case OSXBugFix(Int, Int, Int, reason: String)
  case OSXBugFixRange(Int, Int, Range<Int>, reason: String)

  case iOSAny(/*reason:*/ String)
  case iOSMajor(Int, reason: String)
  case iOSMinor(Int, Int, reason: String)
  case iOSMinorRange(Int, Range<Int>, reason: String)
  case iOSBugFix(Int, Int, Int, reason: String)
  case iOSBugFixRange(Int, Int, Range<Int>, reason: String)

  case iOSSimulatorAny(/*reason:*/ String)

  case LinuxAny(reason: String)

  public var description: String {
    switch self {
    case Custom(_, let reason):
      return "Custom(reason: \(reason))"
    case OSXAny(let reason):
      return "OSX(*, reason: \(reason))"
    case OSXMajor(let major, let reason):
      return "OSX(\(major).*, reason: \(reason))"
    case OSXMinor(let major, let minor, let reason):
      return "OSX(\(major).\(minor), reason: \(reason))"
    case OSXMinorRange(let major, let minorRange, let reason):
      return "OSX(\(major).[\(minorRange)], reason: \(reason))"
    case OSXBugFix(let major, let minor, let bugFix, let reason):
      return "OSX(\(major).\(minor).\(bugFix), reason: \(reason))"
    case OSXBugFixRange(let major, let minor, let bugFixRange, let reason):
      return "OSX(\(major).\(minor).[\(bugFixRange)], reason: \(reason))"

    case iOSAny(let reason):
      return "iOS(*, reason: \(reason))"
    case iOSMajor(let major, let reason):
      return "iOS(\(major).*, reason: \(reason))"
    case iOSMinor(let major, let minor, let reason):
      return "iOS(\(major).\(minor), reason: \(reason))"
    case iOSMinorRange(let major, let minorRange, let reason):
      return "iOS(\(major).[\(minorRange)], reason: \(reason))"
    case iOSBugFix(let major, let minor, let bugFix, let reason):
      return "iOS(\(major).\(minor).\(bugFix), reason: \(reason))"
    case iOSBugFixRange(let major, let minor, let bugFixRange, let reason):
      return "iOS(\(major).\(minor).[\(bugFixRange)], reason: \(reason))"

    case iOSSimulatorAny(let reason):
      return "iOSSimulatorAny(*, reason: \(reason))"

    case LinuxAny(reason: let reason):
      return "LinuxAny(*, reason: \(reason))"
    }
  }

  public func evaluate() -> Bool {
    switch self {
    case Custom(let predicate, _):
      return predicate()

    case OSXAny:
      switch _getRunningOSVersion() {
      case .OSX:
        return true
      default:
        return false
      }

    case OSXMajor(let major, _):
      switch _getRunningOSVersion() {
      case .OSX(major, _, _):
        return true
      default:
        return false
      }

    case OSXMinor(let major, let minor, _):
      switch _getRunningOSVersion() {
      case .OSX(major, minor, _):
        return true
      default:
        return false
      }

    case OSXMinorRange(let major, let minorRange, _):
      switch _getRunningOSVersion() {
      case .OSX(major, let runningMinor, _):
        return minorRange.contains(runningMinor)
      default:
        return false
      }

    case OSXBugFix(let major, let minor, let bugFix, _):
      switch _getRunningOSVersion() {
      case .OSX(major, minor, bugFix):
        return true
      default:
        return false
      }

    case OSXBugFixRange(let major, let minor, let bugFixRange, _):
      switch _getRunningOSVersion() {
      case .OSX(major, minor, let runningBugFix):
        return bugFixRange.contains(runningBugFix)
      default:
        return false
      }

    case iOSAny:
      switch _getRunningOSVersion() {
      case .iOS:
        return true
      default:
        return false
      }

    case iOSMajor(let major, _):
      switch _getRunningOSVersion() {
      case .iOS(major, _, _):
        return true
      default:
        return false
      }

    case iOSMinor(let major, let minor, _):
      switch _getRunningOSVersion() {
      case .iOS(major, minor, _):
        return true
      default:
        return false
      }

    case iOSMinorRange(let major, let minorRange, _):
      switch _getRunningOSVersion() {
      case .iOS(major, let runningMinor, _):
        return minorRange.contains(runningMinor)
      default:
        return false
      }

    case iOSBugFix(let major, let minor, let bugFix, _):
      switch _getRunningOSVersion() {
      case .iOS(major, minor, bugFix):
        return true
      default:
        return false
      }

    case iOSBugFixRange(let major, let minor, let bugFixRange, _):
      switch _getRunningOSVersion() {
      case .iOS(major, minor, let runningBugFix):
        return bugFixRange.contains(runningBugFix)
      default:
        return false
      }

    case iOSSimulatorAny:
      switch _getRunningOSVersion() {
      case .iOSSimulator:
        return true
      default:
        return false
      }

    case LinuxAny:
      switch _getRunningOSVersion() {
      case .Linux:
        return true
      default:
        return false
      }
    }
  }
}

//
// Helpers that verify invariants of various stdlib types.
//

public func checkEquatable<T : Equatable>(
  expectedEqual: Bool, _ lhs: T, _ rhs: T, _ stackTrace: SourceLocStack,
  collectMoreInfo: (()->String)? = nil
) {
  // Test operator '==' that is found through witness tables.
  expectEqual(
    expectedEqual, lhs == rhs, stackTrace: stackTrace, 
    collectMoreInfo: collectMoreInfo)
  expectEqual(
    !expectedEqual, lhs != rhs, stackTrace: stackTrace, 
    collectMoreInfo: collectMoreInfo)
}

public func checkEquatable<T : Equatable>(
  expectedEqual: Bool, _ lhs: T, _ rhs: T,
  file: String = __FILE__, line: UWord = __LINE__,
  collectMoreInfo: (()->String)? = nil
) {
  checkEquatable(
    expectedEqual, lhs, rhs, SourceLocStack().with(SourceLoc(file, line)))
}

public func checkHashable<T : Hashable>(
  expectedEqual: Bool, _ lhs: T, _ rhs: T, _ stackTrace: SourceLocStack,
  collectMoreInfo: (()->String)? = nil
) {
  // Test operator '==' that is found through witness tables.
  expectEqual(
    expectedEqual, lhs == rhs, stackTrace: stackTrace,
    collectMoreInfo: collectMoreInfo)
  expectEqual(
    !expectedEqual, lhs != rhs, stackTrace: stackTrace,
    collectMoreInfo: collectMoreInfo)

  // Test 'hashValue'.
  //
  // If objects are not equal, then the hash value can be different or it can
  // collide.
  if expectedEqual {
    expectEqual(lhs.hashValue, rhs.hashValue,
      stackTrace: stackTrace, collectMoreInfo: collectMoreInfo)
  }
}

public func checkHashable<T : Hashable>(
  expectedEqual: Bool, _ lhs: T, _ rhs: T,
  file: String = __FILE__, line: UWord = __LINE__,
  collectMoreInfo: (()->String)? = nil
) {
  checkHashable(
    expectedEqual, lhs, rhs, SourceLocStack(SourceLoc(file, line)),
    collectMoreInfo: collectMoreInfo)
}

public enum ExpectedComparisonResult {
  case LT, EQ, GT

  public func isLT() -> Bool {
    return self == .LT
  }

  public func isEQ() -> Bool {
    return self == .EQ
  }

  public func isGT() -> Bool {
    return self == .GT
  }

  public func isLE() -> Bool {
    return isLT() || isEQ()
  }

  public func isGE() -> Bool {
    return isGT() || isEQ()
  }

  public func isNE() -> Bool {
    return !isEQ()
  }

  public func flip() -> ExpectedComparisonResult {
    switch self {
    case .LT:
      return .GT
    case .EQ:
      return .EQ
    case .GT:
      return .LT
    }
  }
}

extension ExpectedComparisonResult : CustomStringConvertible {
  public var description: String {
    switch self {
    case .LT:
      return "<"
    case .EQ:
      return "=="
    case .GT:
      return ">"
    }
  }
}

public func checkComparable<T : Comparable>(
  expected: ExpectedComparisonResult,
  _ lhs: T, _ rhs: T, _ stackTrace: SourceLocStack,
  collectMoreInfo: (()->String)? = nil
) {
  expectEqual(expected.isLT(), lhs < rhs,
    stackTrace: stackTrace, collectMoreInfo: collectMoreInfo)
  expectEqual(expected.isLE(), lhs <= rhs,
    stackTrace: stackTrace, collectMoreInfo: collectMoreInfo)
  expectEqual(expected.isGE(), lhs >= rhs,
    stackTrace: stackTrace, collectMoreInfo: collectMoreInfo)
  expectEqual(expected.isGT(), lhs > rhs,
    stackTrace: stackTrace, collectMoreInfo: collectMoreInfo)
}

public func checkComparable<T : Comparable>(
  expected: ExpectedComparisonResult,
  _ lhs: T, _ rhs: T,
  file: String = __FILE__, line: UWord = __LINE__,
  collectMoreInfo: (()->String)? = nil
) {
  checkComparable(expected, lhs, rhs, SourceLocStack(SourceLoc(file, line)),
    collectMoreInfo: collectMoreInfo)
}

public struct CollectionMisuseResiliencyChecks {
  public var callNextOnExhaustedGenerator: Bool = true

  public static var all: CollectionMisuseResiliencyChecks {
    return CollectionMisuseResiliencyChecks()
  }

  public static var none: CollectionMisuseResiliencyChecks {
    return CollectionMisuseResiliencyChecks(
      callNextOnExhaustedGenerator: false)
  }
}

// Generate two overloads: one for _UnitTestArray (which will get
// picked up when the caller passes a literal), and another that
// accepts any appropriate Collection type.
% for genericParam, Element, Expected in zip(
%   ('Expected: CollectionType', 'Element'),
%   ('Expected.Generator.Element', 'Element'),
%   ('Expected', '_UnitTestArray<Element>')):

public func checkGenerator<
  G : GeneratorType, ${genericParam}
  where ${Element} == G.Element
>(
  expected: ${Expected},
  _ generator: G,
  _ sameValue: (${Element}, ${Element}) -> Bool,
  resiliencyChecks: CollectionMisuseResiliencyChecks = .all,
  _ stackTrace: SourceLocStack,
  collectMoreInfo: (()->String)? = nil
) {
  // Copying a `GeneratorType` is allowed.
  var mutableGen = generator
  var actual: _UnitTestArray<${Element}> = []
  while let e = mutableGen.next() {
    actual.append(e)
  }
  expectEqualSequence(
    expected, actual, sameValue,
    stackTrace: stackTrace.withCurrentLoc(),
    collectMoreInfo: collectMoreInfo)

  if resiliencyChecks.callNextOnExhaustedGenerator {
    // Having returned `.None` once, a `GeneratorType` should not generate more
    // elements.
    for i in 0..<10 {
      expectEmpty(
        mutableGen.next(),
        stackTrace: stackTrace.withCurrentLoc(),
        collectMoreInfo: collectMoreInfo)
    }
  }
}

public func checkGenerator<
  G : GeneratorType, ${genericParam}
  where ${Element} == G.Element, ${Element} : Equatable
>(
  expected: ${Expected},
  _ generator: G,
  resiliencyChecks: CollectionMisuseResiliencyChecks = .all,
  _ stackTrace: SourceLocStack,
  collectMoreInfo: (()->String)? = nil
) {
  checkGenerator(
    expected, generator, { $0 == $1 },
    resiliencyChecks: resiliencyChecks,
    stackTrace.withCurrentLoc(),
    collectMoreInfo: collectMoreInfo)
}

public func checkSequence<
  ${genericParam}, S : SequenceType
  where S.Generator.Element == ${Element}
>(
  expected: ${Expected},
  _ sequence: S,
  _ sameValue: (${Element}, ${Element}) -> Bool,
  resiliencyChecks: CollectionMisuseResiliencyChecks = .all,
  _ stackTrace: SourceLocStack,
  collectMoreInfo: (()->String)? = nil
) {
  let expectedCount: Int = numericCast(expected.count())
  checkGenerator(
    expected, sequence.generate(), sameValue,
    resiliencyChecks: resiliencyChecks,
    stackTrace.withCurrentLoc())
  expectGE(
    expectedCount, sequence.underestimateCount(),
    stackTrace: stackTrace.withCurrentLoc(),
    collectMoreInfo: collectMoreInfo)
}

public func checkSequence<
  ${genericParam}, S : SequenceType
  where S.Generator.Element == ${Element}
>(
  expected: ${Expected},
  _ sequence: S,
  _ sameValue: (${Element}, ${Element}) -> Bool,
  resiliencyChecks: CollectionMisuseResiliencyChecks = .all,
  file: String = __FILE__, line: UWord = __LINE__,
  collectMoreInfo: (()->String)? = nil
) {
  checkSequence(
    expected, sequence, sameValue,
    resiliencyChecks: resiliencyChecks,
    SourceLocStack().with(SourceLoc(file, line)),
    collectMoreInfo: collectMoreInfo)
}

public func checkSequence<
  ${genericParam}, S : SequenceType
  where S.Generator.Element == ${Element}, ${Element} : Equatable
>(
  expected: ${Expected},
  _ sequence: S,
  resiliencyChecks: CollectionMisuseResiliencyChecks = .all,
  _ stackTrace: SourceLocStack,
  collectMoreInfo: (()->String)? = nil
) {
  checkSequence(
    expected, sequence, { $0 == $1 },
    resiliencyChecks: resiliencyChecks,
    stackTrace.withCurrentLoc(),
    collectMoreInfo: collectMoreInfo)
}

public func checkSequence<
  ${genericParam}, S : SequenceType
  where S.Generator.Element == ${Element}, ${Element} : Equatable
>(
  expected: ${Expected},
  _ sequence: S,
  resiliencyChecks: CollectionMisuseResiliencyChecks = .all,
  file: String = __FILE__, line: UWord = __LINE__,
  collectMoreInfo: (()->String)? = nil
) {
  checkSequence(
    expected, sequence, { $0 == $1 },
    resiliencyChecks: resiliencyChecks,
    SourceLocStack().with(SourceLoc(file, line)),
    collectMoreInfo: collectMoreInfo)
}

%for traversal in [ 'Forward', 'Bidirectional', 'RandomAccess' ]:

public func check${traversal}Collection<
  ${genericParam}, C : CollectionType
  where
  C.Generator.Element == ${Element},
  C.Index : ${traversal}IndexType
>(
  expected: ${Expected},
  _ collection: C,
  _ sameValue: (${Element}, ${Element}) -> Bool,
  resiliencyChecks: CollectionMisuseResiliencyChecks = .all,
  _ stackTrace: SourceLocStack,
  collectMoreInfo: (()->String)? = nil
) {
  // A `CollectionType` is a multi-pass `SequenceType`.
  for i in 0..<3 {
    checkSequence(
      expected, collection, sameValue,
      resiliencyChecks: resiliencyChecks,
      stackTrace.withCurrentLoc(),
      collectMoreInfo: collectMoreInfo)
  }

  let expectedArray = Array(expected)

  expectEqual(
    expectedArray.count().toIntMax(),
    collection.count().toIntMax(),
    stackTrace: stackTrace.withCurrentLoc(),
    collectMoreInfo: collectMoreInfo)

  for i in 0..<3 {
    if true {
      let startIndex = collection.startIndex
      let endIndex = collection.endIndex

      for i in collection.indices {
        expectEqual(startIndex, collection.startIndex,
          stackTrace: stackTrace.withCurrentLoc()) {
          "Iteration should not change startIndex"
        }
        expectEqual(endIndex, collection.endIndex,
          stackTrace: stackTrace.withCurrentLoc()) {
          "Iteration should not change endIndex"
        }
      }
    }

    var allIndices: [C.Index] = []
    for i in collection.indices {
      allIndices.append(i)
    }

    if expectedArray.count() >= 2 {
      for i in 0..<allIndices.count()-1 {
        var successor1 = allIndices[i].successor()
        var successor2 = allIndices[i]
        successor2++
        var successor3 = allIndices[i]
        ++successor3
        for s in [ successor1, successor2, successor3 ] {
          expectEqual(
            allIndices[i + 1], s,
            stackTrace: stackTrace.withCurrentLoc())
          expectEqual(
            expectedArray[i + 1],
            collection[s],
            sameValue,
            stackTrace: stackTrace.withCurrentLoc())
        }
      }
%   if traversal == "Bidirectional":
      for i in 1..<allIndices.count() {
        var predecessor1 = allIndices[i].predecessor()
        var predecessor2 = allIndices[i]
        predecessor2--
        var predecessor3 = allIndices[i]
        --predecessor3
        for p in [ predecessor1, predecessor2, predecessor3 ] {
          expectEqual(
            allIndices[i - 1], p,
            stackTrace: stackTrace.withCurrentLoc())
          expectEqual(
            expectedArray[i - 1], collection[p],
            sameValue,
            stackTrace: stackTrace.withCurrentLoc())
        }
      }
      for i in 1..<allIndices.count() {
        var index = allIndices[i]
        --index
        ++index
        expectEqual(
          allIndices[i], index,
          stackTrace: stackTrace.withCurrentLoc())
        expectEqual(
          expectedArray[i], collection[index],
          sameValue,
          stackTrace: stackTrace.withCurrentLoc())
      }
%   end
    }

    if true {
      var allIndices2: [C.Index] = []
      for i in collection.indices {
        allIndices2.append(i)
      }

      expectEqualSequence(
        allIndices, allIndices2,
        stackTrace: stackTrace.withCurrentLoc()) {
        "iteration should not invalidate indices"
      }

      expectEqualSequence(
        expectedArray,
        allIndices._prext_map { collection[$0] },
        sameValue,
        stackTrace: stackTrace.withCurrentLoc())
      expectEqualSequence(
        expectedArray,
        allIndices2._prext_map { collection[$0] },
        sameValue,
        stackTrace: stackTrace.withCurrentLoc())
    }
  }

  // FIXME: more checks for bidirectional and random access collections.
}

public func check${traversal}Collection<
  ${genericParam}, C : CollectionType
  where
  C.Generator.Element == ${Element},
  C.Index : ${traversal}IndexType
>(
  expected: ${Expected},
  _ collection: C,
  _ sameValue: (${Element}, ${Element}) -> Bool,
  resiliencyChecks: CollectionMisuseResiliencyChecks = .all,
  file: String = __FILE__, line: UWord = __LINE__,
  collectMoreInfo: (()->String)? = nil
) {
  check${traversal}Collection(
    expected, collection, sameValue,
    resiliencyChecks: resiliencyChecks,
    SourceLocStack().with(SourceLoc(file, line)),
    collectMoreInfo: collectMoreInfo)
}

public func check${traversal}Collection<
  ${genericParam}, C : CollectionType
  where
  C.Generator.Element == ${Element},
  C.Index : ${traversal}IndexType,
  ${Element} : Equatable
>(
  expected: ${Expected},
  _ collection: C,
  resiliencyChecks: CollectionMisuseResiliencyChecks = .all,
  _ stackTrace: SourceLocStack,
  collectMoreInfo: (()->String)? = nil
) {
  check${traversal}Collection(
    expected, collection, { $0 == $1 },
    resiliencyChecks: resiliencyChecks,
    stackTrace.withCurrentLoc(),
    collectMoreInfo: collectMoreInfo)
}

public func check${traversal}Collection<
  ${genericParam}, C : CollectionType
  where
  C.Generator.Element == ${Element},
  C.Index : ${traversal}IndexType,
  ${Element} : Equatable
>(
  expected: ${Expected},
  _ collection: C,
  resiliencyChecks: CollectionMisuseResiliencyChecks = .all,
  file: String = __FILE__, line: UWord = __LINE__,
  collectMoreInfo: (()->String)? = nil
) {
  check${traversal}Collection(
    expected, collection, { $0 == $1 },
    resiliencyChecks: resiliencyChecks,
    SourceLocStack().with(SourceLoc(file, line)),
    collectMoreInfo: collectMoreInfo)
}

% end

public func checkSliceableWithBidirectionalIndex<
  ${genericParam}, S : Sliceable
  where
  S.Generator.Element == ${Element},
  S.SubSlice.Generator.Element == ${Element},
  S.Index : BidirectionalIndexType,
  S.SubSlice.Index : BidirectionalIndexType,
  ${Element} : Equatable
>(
  expected: ${Expected}, 
  _ sliceable: S, _ stackTrace: SourceLocStack
) {
  // A `Sliceable` is a `CollectionType`.
  checkBidirectionalCollection(expected, sliceable, stackTrace.withCurrentLoc())

  let expectedArray = _UnitTestArray(expected)
  
  var start = sliceable.startIndex
  for startNumericIndex in 0...expectedArray.count() {
    if start != sliceable.endIndex {
      ++start
      --start
      ++start
      --start
    }
    var end = start
    for endNumericIndex in startNumericIndex...expectedArray.count() {
      if end != sliceable.endIndex {
        ++end
        --end
        ++end
        --end
      }
      let expectedSlice = expectedArray[startNumericIndex..<endNumericIndex]
      let slice = sliceable[start..<end]
      checkBidirectionalCollection(
        expectedSlice, slice, stackTrace.withCurrentLoc())

      if end != sliceable.endIndex {
        ++end
      }
    }
    if start != sliceable.endIndex {
      ++start
    }
  }
}

% end

public func nthIndex<C: CollectionType>(x: C, _ n: Int) -> C.Index {
  return advance(x.startIndex, numericCast(n))
}

public func nth<C: CollectionType>(x: C, _ n: Int) -> C.Generator.Element {
  return x[nthIndex(x, n)]
}

public func checkRangeReplaceable<
  C: RangeReplaceableCollectionType,
  N: CollectionType
where
  C.Generator.Element : Equatable, C.Generator.Element == N.Generator.Element
>(
  makeCollection: ()->C,
  _ makeNewValues: (Int)->N
) {
  typealias A = C

  // First make an independent copy of the array that we can use for
  // comparison later.
  let source = _UnitTestArray<A.Generator.Element>(makeCollection())

  for (ix, i) in source.indices.enumerate() {
    for (jx_, j) in (i..<source.endIndex).enumerate() {
      let jx = jx_ + ix
      
      let oldCount = jx - ix
      for newCount in 0..<(2 * oldCount) {
        let newValues = makeNewValues(newCount)

        func reportFailure(inout a: A, _ message: String) {
          println("\(message) when replacing indices \(ix)...\(jx)")
          println("  in \(_UnitTestArray(source)) with \(_UnitTestArray(newValues))")
          println("  yielding \(_UnitTestArray(a))")
          println("====================================")
          expectTrue(false)
        }

        var a = makeCollection()
     
        a.replaceRange(nthIndex(a, ix)..<nthIndex(a, jx), with: newValues)
        let growth = newCount - oldCount
        
        let expectedCount = source.count() + growth
        let actualCount = numericCast(a.count()) as Int
        if actualCount != expectedCount {
          reportFailure(
            &a, "\(actualCount) != expected count \(expectedCount)")
        }
        
        for (kx, k) in a.indices.enumerate() {
          let expectedValue = kx < ix ? nth(source, kx)
          : kx < jx + growth ? nth(newValues, kx - ix)
          : nth(source, kx - growth)

          if a[k] != expectedValue {
            reportFailure(
              &a,
              // FIXME: why do we need to break this string into two parts?
              "a[\(kx)] = "
              + "\(a[k]) != expected value \(expectedValue)")
          }
        }
      }
    }
  }
}

public func expectEqualSequence<
  Expected: SequenceType,
  Actual: SequenceType
  where Expected.Generator.Element == Actual.Generator.Element,
     Expected.Generator.Element : Equatable
>(
    expected: Expected, _ actual: Actual,
    stackTrace: SourceLocStack? = nil,
    file: String = __FILE__, line: UWord = __LINE__,
    collectMoreInfo: (()->String)? = nil
) {
  expectEqualSequence(
    expected, actual, { $0 == $1 }, stackTrace: stackTrace,
    file: file, line: line, collectMoreInfo: collectMoreInfo)
}

public func expectEqualSequence<
  Expected : SequenceType,
  Actual : SequenceType,
  T : Equatable,
  U : Equatable
  where Expected.Generator.Element == Actual.Generator.Element,
     Expected.Generator.Element == (T, U)
>(
    expected: Expected, _ actual: Actual,
    stackTrace: SourceLocStack? = nil,
    file: String = __FILE__, line: UWord = __LINE__,
    collectMoreInfo: (()->String)? = nil
) {
  expectEqualSequence(
    expected, actual, { $0.0 == $1.0 && $0.1 == $1.1 },
    stackTrace: stackTrace, file: file, line: line,
    collectMoreInfo: collectMoreInfo)
}

public func expectEqualSequence<
  Expected: SequenceType,
  Actual: SequenceType
  where Expected.Generator.Element == Actual.Generator.Element
>(
    expected: Expected, _ actual: Actual,
    _ sameValue: (Expected.Generator.Element, Expected.Generator.Element)->Bool,
    stackTrace: SourceLocStack? = nil,
    file: String = __FILE__, line: UWord = __LINE__,
    collectMoreInfo: (()->String)? = nil
) {
  if !expected.elementsEqual(actual, isEquivalent: sameValue) {
    _anyExpectFailed = true
    println("check failed at \(file), line \(line)")
    _printStackTrace(stackTrace)
    println("expected elements: \"\(expected)\"")
    println("actual: \"\(actual)\" (of type \(_stdlib_getDemangledTypeName(actual)))")
    if collectMoreInfo != nil { println(collectMoreInfo!()) }
    println()
  }
}

public func expectEqualsUnordered<
    Expected : SequenceType,
    Actual : SequenceType
    where Expected.Generator.Element == Actual.Generator.Element
>(
    expected: Expected, _ actual: Actual,
    _ compare: (Expected.Generator.Element, Expected.Generator.Element)
      -> ExpectedComparisonResult,
    stackTrace: SourceLocStack? = nil,
    file: String = __FILE__, line: UWord = __LINE__,
    collectMoreInfo: (()->String)? = nil
) {
  let x: [Expected.Generator.Element] = sorted(
    Array(expected), compose(compare, { $0.isLT() }))
  let y: [Actual.Generator.Element] = sorted(
    Array(actual), compose(compare, { $0.isLT() }))
  expectEqualSequence(
    x, y, compose(compare, { $0.isEQ() }), stackTrace: stackTrace,
    file: file, line: line, collectMoreInfo: collectMoreInfo)
}

public func expectEqualsUnordered<
  Expected : SequenceType,
  Actual : SequenceType
  where
  Expected.Generator.Element == Actual.Generator.Element,
  Expected.Generator.Element : Comparable
>(
  expected: Expected, _ actual: Actual,
  stackTrace: SourceLocStack? = nil,
  file: String = __FILE__, line: UWord = __LINE__,
  collectMoreInfo: (()->String)? = nil
) {
  func compare(
    lhs: Expected.Generator.Element,
    rhs: Expected.Generator.Element
  ) -> ExpectedComparisonResult {
    if lhs < rhs {
      return .LT
    }
    if lhs == rhs {
      return .EQ
    }
    return .GT
  }
  expectEqualsUnordered(
    expected, actual, compare,
    stackTrace: stackTrace.map { $0.withCurrentLoc() },
    file: file, line: line, collectMoreInfo: collectMoreInfo)
}

public func expectEqualsUnordered<T : Comparable>(
  expected: [T], _ actual: [T],
  stackTrace: SourceLocStack? = nil,
  file: String = __FILE__, line: UWord = __LINE__,
  collectMoreInfo: (()->String)? = nil
) {
  let x = sorted(expected)
  let y = sorted(actual)
  expectEqualSequence(
    x, y, { $0 == $1 }, stackTrace: stackTrace,
    file: file, line: line, collectMoreInfo: collectMoreInfo)
}

/// A nominal type that is equivalent to a tuple of two elements.
///
/// We need a nominal type because we can't add protocol conformances to
/// tuples.
struct Pair<T : Comparable> : Comparable {
  init(_ first: T, _ second: T) {
    self.first = first
    self.second = second
  }

  var first: T
  var second: T
}

func == <T>(lhs: Pair<T>, rhs: Pair<T>) -> Bool {
  return lhs.first == rhs.first && lhs.second == rhs.second
}

func < <T>(lhs: Pair<T>, rhs: Pair<T>) -> Bool {
  return [ lhs.first, lhs.second ].lexicographicalCompare(
    [ rhs.first, rhs.second ])
}

public func expectEqualsUnordered<T : Comparable>(
  expected: [(T, T)], _ actual: [(T, T)],
  stackTrace: SourceLocStack? = nil,
  file: String = __FILE__, line: UWord = __LINE__,
  collectMoreInfo: (()->String)? = nil
) {
  let x = sorted(expected, { Pair($0.0, $0.1) < Pair($1.0, $1.1) })
  let y = sorted(actual, { Pair($0.0, $0.1) < Pair($1.0, $1.1) })
  expectEqualSequence(
    x, y, { Pair($0.0, $0.1) == Pair($1.0, $1.1) }, stackTrace: stackTrace,
    file: file, line: line, collectMoreInfo: collectMoreInfo)
}

/*

This code crashes the compiler.  If we could use this code, we wouldn't need
the explicit overload for [(T, T)].

rdar://problem/19792730
rdar://problem/19792768

public func expectEqualsUnordered<
    Expected : SequenceType,
    Actual : SequenceType,
    T : Comparable
    where
      Expected.Generator.Element == Actual.Generator.Element,
      Expected.Generator.Element == (T, T)
>(
    expected: Expected, _ actual: Actual,
    stackTrace: SourceLocStack? = nil,
    file: String = __FILE__, line: UWord = __LINE__,
    collectMoreInfo: (()->String)? = nil
) {
  func comparePairLess(lhs: (T, T), rhs: (T, T)) -> Bool {
    return lexicographicalCompare([ lhs.0, lhs.1 ], [ rhs.0, rhs.1 ])
  }

  let x: [(T, T)] = sorted(Array(expected), comparePairLess)
  let y: [(T, T)] = sorted(Array(actual), comparePairLess)

  func comparePairEquals(lhs: (T, T), rhs: (T, T)) -> Bool {
    return lhs.0 == rhs.0 && lhs.1 == rhs.1
  }

  expectEqualSequence(
    x, y, comparePairEquals, stackTrace: stackTrace,
    file: file, line: line, collectMoreInfo: collectMoreInfo)
}*/

public func expectEqualFunctionsForDomain<ArgumentType, Result : Equatable>(
    arguments: [ArgumentType], _ function1: ArgumentType -> Result,
    _ function2: ArgumentType -> Result
) {
  for a in arguments {
    let expected = function1(a)
    let actual = function2(a)
    expectEqual(expected, actual) {
      "where the argument is: \(a)"
    }
  }
}

public func expectEqualMethodsForDomain<
  SelfType, ArgumentType, Result : Equatable
>(
  selfs: [SelfType], _ arguments: [ArgumentType],
  _ function1: SelfType -> ArgumentType -> Result,
  _ function2: SelfType -> ArgumentType -> Result
) {
  for s in selfs {
    for a in arguments {
      let expected = function1(s)(a)
      let actual = function2(s)(a)
      expectEqual(expected, actual) {
        "where the first argument is: \(s)\nand the second argument is: \(a)"
      }
    }
  }
}

public func expectEqualUnicodeScalars(
  expected: _UnitTestArray<UInt32>, _ actual: String,
  stackTrace: SourceLocStack? = nil,
  file: String = __FILE__, line: UWord = __LINE__,
  collectMoreInfo: (()->String)? = nil
) {
  let actualUnicodeScalars = _UnitTestArray(lazy(actual.unicodeScalars).map { $0.value })
  if !expected.elementsEqual(actualUnicodeScalars) {
    _anyExpectFailed = true
    println("check failed at \(file), line \(line)")
    _printStackTrace(stackTrace)
    println("expected elements: \"\(asHex(expected))\"")
    println("actual: \"\(asHex(actualUnicodeScalars))\"")
    if collectMoreInfo != nil { println(collectMoreInfo!()) }
    println()
  }

}

public func expectPrinted<T>(
  expectedOneOf patterns: _UnitTestArray<String>, _ object: T,
  file: StaticString = __FILE__, line: UWord = __LINE__
) {
  let actual = String(object)
  if !patterns.contains(actual) {
    _anyExpectFailed = true
    println("check failed at \(file), line \(line)")
    println("expected: any of \(patterns.debugDescription)")
    println("actual: \"\(actual)\"")
    println()
  }
}

public func expectPrinted<T>(
  expected: String, _ object: T,
  file: StaticString = __FILE__, line: UWord = __LINE__
) {
  expectPrinted(expectedOneOf: [expected], object, file: file, line: line)
}

public func expectDebugPrinted<T>(
  expectedOneOf patterns: _UnitTestArray<String>, _ object: T,
  file: StaticString = __FILE__, line: UWord = __LINE__
) {
  let actual = String(reflecting: object)
  if !patterns.contains(actual) {
    _anyExpectFailed = true
    println("check failed at \(file), line \(line)")
    println("expected: any of \(patterns.debugDescription)")
    println("actual: \"\(actual)\"")
    println()
  }
}

public func expectDebugPrinted<T>(
  expected: String, _ object: T,
  file: StaticString = __FILE__, line: UWord = __LINE__
) {
  expectDebugPrinted(expectedOneOf: [expected], object, file: file, line: line)
}

func compose<A, B, C>(f: A -> B, _ g: B -> C) -> A -> C {
  return { a in
    return g(f(a))
  }
}

/// State that is created every time a fresh generator is created with
/// `MinimalSequence.generate()`.
internal class _MinimalGeneratorPrivateState<T> {
  internal init() {}

  internal var returnedNilCounter: Int = 0
}

/// State shared by all generators of a MinimalSequence.
internal class _MinimalGeneratorSharedState<T> {
  internal init(_ data: [T]) {
    self.data = data
  }

  internal let data: [T]
  internal var i: Int = 0
  internal var underestimatedCount: Int = 0
}

//===----------------------------------------------------------------------===//
// MinimalGenerator
//===----------------------------------------------------------------------===//

/// A GeneratorType that implements the protocol contract in the most
/// narrow way possible.
///
/// This generator will return `nil` only once.
public struct MinimalGenerator<T> : GeneratorType {
  public init<S : SequenceType where S.Generator.Element == T>(_ s: S) {
    self._sharedState = _MinimalGeneratorSharedState(Array(s))
  }

  public init(_ data: [T]) {
    self._sharedState = _MinimalGeneratorSharedState(data)
  }

  internal init(_ _sharedState: _MinimalGeneratorSharedState<T>) {
    self._sharedState = _sharedState
  }

  public func next() -> T? {
    if _sharedState.i == _sharedState.data.count() {
      if isConsumed {
        expectUnreachable() { "next() was called on a consumed generator" }
      }
      ++_privateState.returnedNilCounter
      return nil
    }
    return _sharedState.data[_sharedState.i++]
  }

  public var isConsumed: Bool {
    return returnedNilCounter >= 1
  }

  public var returnedNilCounter: Int {
    return _privateState.returnedNilCounter
  }

  internal let _privateState: _MinimalGeneratorPrivateState<T> =
    _MinimalGeneratorPrivateState()
  internal let _sharedState: _MinimalGeneratorSharedState<T>
}

//===----------------------------------------------------------------------===//
// MinimalSequence
//===----------------------------------------------------------------------===//

public enum UnderestimateCountBehavior {
  /// Return the actual number of elements.
  case Precise

  /// Return the actual number of elements divided by 2.
  case Half

  /// Return an overestimated count.  Useful to test how algorithms reserve
  /// memory.
  case Overestimate

  /// Return the provided value.
  case Value(Int)
}

/// A SequenceType that implements the protocol contract in the most
/// narrow way possible.
///
/// This sequence is consumed when its generator is advanced.
public struct MinimalSequence<T> : SequenceType {
  public init<S : SequenceType where S.Generator.Element == T>(
    _ s: S,
    underestimatedCount: UnderestimateCountBehavior = .Value(0)
  ) {
    let data = Array(s)
    self._sharedState = _MinimalGeneratorSharedState(data)

    switch underestimatedCount {
    case .Precise:
      self._sharedState.underestimatedCount = data.count()

    case .Half:
      self._sharedState.underestimatedCount = data.count() / 2

    case .Overestimate:
      self._sharedState.underestimatedCount = data.count() * 3 + 5

    case .Value(let count):
      self._sharedState.underestimatedCount = count
    }
  }

  public func generate() -> MinimalGenerator<T> {
    return MinimalGenerator(_sharedState)
  }

  public func underestimateCount() -> Int {
    return max(0, self._sharedState.underestimatedCount - self._sharedState.i)
  }

  internal let _sharedState: _MinimalGeneratorSharedState<T>
}

//===----------------------------------------------------------------------===//
// MinimalForwardIndex
//===----------------------------------------------------------------------===//

% for Distance in [ '', 'Int32' ]:

public struct MinimalForward${Distance}Index : ForwardIndexType {
% if Distance != '':
  typealias Distance = ${Distance}
% end

  public init(position: Int, endIndex: Int) {
    self.position = position
    self.endIndex = endIndex
  }

  public init(position: Int, startIndex _: Int, endIndex: Int) {
    self.position = position
    self.endIndex = endIndex
  }

  public func successor() -> MinimalForward${Distance}Index {
    expectNotEqual(endIndex, position)
    return MinimalForward${Distance}Index(
      position: position + 1,
      endIndex: endIndex)
  }

  public let position: Int
  public let endIndex: Int
}

public func == (
  lhs: MinimalForward${Distance}Index,
  rhs: MinimalForward${Distance}Index
) -> Bool {
  return lhs.position == rhs.position
}

% end

//===----------------------------------------------------------------------===//
// MinimalBidirectionalIndex
//===----------------------------------------------------------------------===//

public struct MinimalBidirectionalIndex : BidirectionalIndexType {
  public init(position: Int, startIndex: Int, endIndex: Int) {
    self.position = position
    self.startIndex = startIndex
    self.endIndex = endIndex
  }

  public func successor() -> MinimalBidirectionalIndex {
    expectNotEqual(endIndex, position)
    return MinimalBidirectionalIndex(
      position: position + 1, startIndex: startIndex, endIndex: endIndex)
  }

  public func predecessor() -> MinimalBidirectionalIndex {
    expectNotEqual(startIndex, position)
    return MinimalBidirectionalIndex(
      position: position - 1, startIndex: startIndex, endIndex: endIndex)
  }

  public let position: Int
  public let startIndex: Int
  public let endIndex: Int
}

public func == (
  lhs: MinimalBidirectionalIndex,
  rhs: MinimalBidirectionalIndex
) -> Bool {
  return lhs.position == rhs.position
}

//===----------------------------------------------------------------------===//
// MinimalRandomAccessIndex
//===----------------------------------------------------------------------===//

public struct MinimalRandomAccessIndex : RandomAccessIndexType {
  public init(position: Int, startIndex: Int, endIndex: Int) {
    self.position = position
    self.startIndex = startIndex
    self.endIndex = endIndex
  }

  public func successor() -> MinimalRandomAccessIndex {
    expectNotEqual(endIndex, position)
    return MinimalRandomAccessIndex(
      position: position + 1, startIndex: startIndex, endIndex: endIndex)
  }

  public func predecessor() -> MinimalRandomAccessIndex {
    expectNotEqual(startIndex, position)
    return MinimalRandomAccessIndex(
      position: position - 1, startIndex: startIndex, endIndex: endIndex)
  }

  public func distanceTo(other: MinimalRandomAccessIndex) -> Int {
    return other.position - position
  }

  public func advancedBy(n: Int) -> MinimalRandomAccessIndex {
    expectNotEqual(endIndex, position)
    let newPosition = position + n
    expectLE(startIndex, newPosition)
    expectGE(endIndex, newPosition)
    return MinimalRandomAccessIndex(
      position: newPosition, startIndex: startIndex, endIndex: endIndex)
  }

  public let position: Int
  public let startIndex: Int
  public let endIndex: Int
}

public func == (
  lhs: MinimalRandomAccessIndex,
  rhs: MinimalRandomAccessIndex
) -> Bool {
  return lhs.position == rhs.position
}

//===----------------------------------------------------------------------===//
// Minimal***Collection
//===----------------------------------------------------------------------===//

% for traversal in [ 'Forward', 'Bidirectional', 'RandomAccess' ]:
%   for mutable in [ False, True ]:
// This comment is a workaround for <rdar://problem/18900352> gyb miscompiles nested loops
%     Self = 'Minimal%s%sCollection' % ('Mutable' if mutable else '', traversal)
%     Index = 'Minimal%sIndex' % traversal

/// A minimal implementation of `CollectionType` with extra checks.
public struct ${Self}<T> : ${'MutableCollectionType' if mutable else 'CollectionType'} {
  public init<S : SequenceType where S.Generator.Element == T>(
    _ s: S,
    underestimatedCount: UnderestimateCountBehavior = .Value(0)
  ) {
    self._elements = Array(s)

    switch underestimatedCount {
    case .Precise:
      self.underestimatedCount = _elements.count()

    case .Half:
      self.underestimatedCount = _elements.count() / 2

    case .Overestimate:
      self.underestimatedCount = _elements.count() * 3 + 5

    case .Value(let count):
      self.underestimatedCount = count
    }
  }

  public func generate() -> MinimalGenerator<T> {
    return MinimalGenerator(_elements)
  }

  public var startIndex: ${Index} {
    return ${Index}(
      position: 0,
      startIndex: 0,
      endIndex: _elements.endIndex)
  }

  public var endIndex: ${Index} {
    return ${Index}(
      position: _elements.endIndex,
      startIndex: 0,
      endIndex: _elements.endIndex)
  }

  public subscript(i: ${Index}) -> T {
    get {
      return _elements[i.position]
    }
%     if mutable:
    set {
      _elements[i.position] = newValue
    }
%     end
  }

  public func underestimateCount() -> Int {
    return underestimatedCount
  }

  public var underestimatedCount: Int

  internal var _elements: [T]
}

%   end
% end

//===----------------------------------------------------------------------===//
// Minimal***RangeReplaceableCollectionType
//===----------------------------------------------------------------------===//

%for traversal in [ 'Forward', 'Bidirectional', 'RandomAccess' ]:
%  Self = 'Minimal%sRangeReplaceableCollectionType' % traversal
%  Index = 'Minimal%sIndex' % traversal

/// A minimal implementation of `RangeReplaceableCollectionType` with extra
/// checks.
public struct ${Self}<T> : RangeReplaceableCollectionType {

  public init<S : SequenceType where S.Generator.Element == T>(
    _ s: S,
    underestimatedCount: UnderestimateCountBehavior = .Value(0)
  ) {
    self.elements = Array(s)

    switch underestimatedCount {
    case .Precise:
      self.underestimatedCount = elements.count()

    case .Half:
      self.underestimatedCount = elements.count() / 2

    case .Overestimate:
      self.underestimatedCount = elements.count() * 3 + 5

    case .Value(let count):
      self.underestimatedCount = count
    }
  }

  public init() {
    self.underestimatedCount = 0
    self.elements = []
  }

  public func generate() -> MinimalGenerator<T> {
    return MinimalGenerator(elements)
  }

  public func underestimateCount() -> Int {
    return underestimatedCount
  }

  public var startIndex: ${Index} {
    return ${Index}(
      position: 0,
      startIndex: 0,
      endIndex: elements.endIndex)
  }

  public var endIndex: ${Index} {
    return ${Index}(
      position: elements.endIndex,
      startIndex: 0,
      endIndex: elements.endIndex)
  }

  public subscript(i: ${Index}) -> T {
    return elements[i.position]
  }

  public mutating func reserveCapacity(n: Int) {
    elements.reserveCapacity(n)
    reservedCapacity = max(reservedCapacity, n)
  }

  public mutating func append(x: T) {
    elements.append(x)
  }

  public mutating func extend<
    S : SequenceType where S.Generator.Element == T
  >(newElements: S) {
    elements.extend(newElements)
  }

  public mutating func replaceRange<
    C : CollectionType where C.Generator.Element == T
  >(
    subRange: Range<${Index}>, with newElements: C
  ) {
    elements.replaceRange(
      subRange.startIndex.position..<subRange.endIndex.position,
      with: newElements)
  }

  public mutating func insert(newElement: T, atIndex i: ${Index}) {
    elements.insert(newElement, atIndex: i.position)
  }

  public mutating func splice<
    S : CollectionType where S.Generator.Element == T
  >(newElements: S, atIndex i: ${Index}) {
    elements.splice(newElements, atIndex: i.position)
  }

  public mutating func removeAtIndex(i: ${Index}) -> T {
    return elements.removeAtIndex(i.position)
  }

  public mutating func removeRange(subRange: Range<${Index}>) {
    elements.removeRange(
      subRange.startIndex.position..<subRange.endIndex.position
    )
  }

  public mutating func removeAll(keepCapacity keepCapacity: Bool = false) {
    // Ignore the value of `keepCapacity`.
    elements.removeAll(keepCapacity: false)
  }

  public var underestimatedCount: Int
  public var reservedCapacity: Int = 0

  public var elements: [T]
}

%end

/// A type that does not conform to any protocols.
///
/// This type can be used to check that generic functions don't rely on any
/// conformances.
public struct OpaqueValue<Underlying> {
  public var value: Underlying
  public var identity: Int

  public init(_ value: Underlying) {
    self.value = value
    self.identity = 0
  }

  public init(_ value: Underlying, identity: Int) {
    self.value = value
    self.identity = identity
  }
}

/// A type that conforms only to `Equatable`.
///
/// This type can be used to check that generic functions don't rely on any
/// other conformances.
public struct MinimalEquatableValue : Equatable {
  public static var timesEqualEqualWasCalled: Int = 0

  public var value: Int
  public var identity: Int

  public init(_ value: Int) {
    self.value = value
    self.identity = 0
  }

  public init(_ value: Int, identity: Int) {
    self.value = value
    self.identity = identity
  }
}
public func == (
  lhs: MinimalEquatableValue,
  rhs: MinimalEquatableValue
) -> Bool {
  ++MinimalEquatableValue.timesEqualEqualWasCalled
  return lhs.value == rhs.value
}

% for kind in [ 'Value', 'Class' ]:
%   Self = 'MinimalHashable%s' % kind

/// A type that conforms only to `Equatable` and `Hashable`.
///
/// This type can be used to check that generic functions don't rely on any
/// other conformances.
public struct ${Self} : Equatable, Hashable {
  public static var timesEqualEqualWasCalled: Int = 0
  public static var timesHashValueWasCalled: Int = 0

  public var value: Int
  public var identity: Int

  public init(_ value: Int) {
    self.value = value
    self.identity = 0
  }

  public init(_ value: Int, identity: Int) {
    self.value = value
    self.identity = identity
  }

  public var hashValue: Int {
    ++${Self}.timesHashValueWasCalled
    return value.hashValue
  }
}

public func == (
  lhs: ${Self},
  rhs: ${Self}
) -> Bool {
  ++${Self}.timesEqualEqualWasCalled
  return lhs.value == rhs.value
}

% end

/// A type that conforms only to `Equatable` and `Comparable`.
///
/// This type can be used to check that generic functions don't rely on any
/// other conformances.
public struct MinimalComparableValue : Equatable, Comparable {
  public static var timesEqualEqualWasCalled: Int = 0
  public static var timesLessWasCalled: Int = 0

  public var value: Int
  public var identity: Int

  public init(_ value: Int) {
    self.value = value
    self.identity = 0
  }

  public init(_ value: Int, identity: Int) {
    self.value = value
    self.identity = identity
  }
}

public func == (
  lhs: MinimalComparableValue,
  rhs: MinimalComparableValue
) -> Bool {
  ++MinimalComparableValue.timesEqualEqualWasCalled
  return lhs.value == rhs.value
}

public func < (
  lhs: MinimalComparableValue,
  rhs: MinimalComparableValue
) -> Bool {
  ++MinimalComparableValue.timesLessWasCalled
  return lhs.value < rhs.value
}

// ${'Local Variables'}:
// eval: (read-only-mode 1)
// End: