employ-front/node_modules/semver/semver.js

exports = module.exports = SemVer

var debug
/* istanbul ignore next */
if (typeof process === 'object' &&
    process.env &&
    process.env.NODE_DEBUG &&
    /\bsemver\b/i.test(process.env.NODE_DEBUG)) {
  debug = function () {
    var args = Array.prototype.slice.call(arguments, 0)
    args.unshift('SEMVER')
    console.log.apply(console, args)
  }
} else {
  debug = function () {}
}

// Note: this is the semver.org version of the spec that it implements
// Not necessarily the package version of this code.
exports.SEMVER_SPEC_VERSION = '2.0.0'

var MAX_LENGTH = 256
var MAX_SAFE_INTEGER = Number.MAX_SAFE_INTEGER ||
  /* istanbul ignore next */ 9007199254740991

// Max safe segment length for coercion.
var MAX_SAFE_COMPONENT_LENGTH = 16

var MAX_SAFE_BUILD_LENGTH = MAX_LENGTH - 6

// The actual regexps go on exports.re
var re = exports.re = []
var safeRe = exports.safeRe = []
var src = exports.src = []
var t = exports.tokens = {}
var R = 0

function tok (n) {
  t[n] = R++
}

var LETTERDASHNUMBER = '[a-zA-Z0-9-]'

// Replace some greedy regex tokens to prevent regex dos issues. These regex are
// used internally via the safeRe object since all inputs in this library get
// normalized first to trim and collapse all extra whitespace. The original
// regexes are exported for userland consumption and lower level usage. A
// future breaking change could export the safer regex only with a note that
// all input should have extra whitespace removed.
var safeRegexReplacements = [
  ['\\s', 1],
  ['\\d', MAX_LENGTH],
  [LETTERDASHNUMBER, MAX_SAFE_BUILD_LENGTH],
]

function makeSafeRe (value) {
  for (var i = 0; i < safeRegexReplacements.length; i++) {
    var token = safeRegexReplacements[i][0]
    var max = safeRegexReplacements[i][1]
    value = value
      .split(token + '*').join(token + '{0,' + max + '}')
      .split(token + '+').join(token + '{1,' + max + '}')
  }
  return value
}

// The following Regular Expressions can be used for tokenizing,
// validating, and parsing SemVer version strings.

// ## Numeric Identifier
// A single `0`, or a non-zero digit followed by zero or more digits.

tok('NUMERICIDENTIFIER')
src[t.NUMERICIDENTIFIER] = '0|[1-9]\\d*'
tok('NUMERICIDENTIFIERLOOSE')
src[t.NUMERICIDENTIFIERLOOSE] = '\\d+'

// ## Non-numeric Identifier
// Zero or more digits, followed by a letter or hyphen, and then zero or
// more letters, digits, or hyphens.

tok('NONNUMERICIDENTIFIER')
src[t.NONNUMERICIDENTIFIER] = '\\d*[a-zA-Z-]' + LETTERDASHNUMBER + '*'

// ## Main Version
// Three dot-separated numeric identifiers.

tok('MAINVERSION')
src[t.MAINVERSION] = '(' + src[t.NUMERICIDENTIFIER] + ')\\.' +
                   '(' + src[t.NUMERICIDENTIFIER] + ')\\.' +
                   '(' + src[t.NUMERICIDENTIFIER] + ')'

tok('MAINVERSIONLOOSE')
src[t.MAINVERSIONLOOSE] = '(' + src[t.NUMERICIDENTIFIERLOOSE] + ')\\.' +
                        '(' + src[t.NUMERICIDENTIFIERLOOSE] + ')\\.' +
                        '(' + src[t.NUMERICIDENTIFIERLOOSE] + ')'

// ## Pre-release Version Identifier
// A numeric identifier, or a non-numeric identifier.

tok('PRERELEASEIDENTIFIER')
src[t.PRERELEASEIDENTIFIER] = '(?:' + src[t.NUMERICIDENTIFIER] +
                            '|' + src[t.NONNUMERICIDENTIFIER] + ')'

tok('PRERELEASEIDENTIFIERLOOSE')
src[t.PRERELEASEIDENTIFIERLOOSE] = '(?:' + src[t.NUMERICIDENTIFIERLOOSE] +
                                 '|' + src[t.NONNUMERICIDENTIFIER] + ')'

// ## Pre-release Version
// Hyphen, followed by one or more dot-separated pre-release version
// identifiers.

tok('PRERELEASE')
src[t.PRERELEASE] = '(?:-(' + src[t.PRERELEASEIDENTIFIER] +
                  '(?:\\.' + src[t.PRERELEASEIDENTIFIER] + ')*))'

tok('PRERELEASELOOSE')
src[t.PRERELEASELOOSE] = '(?:-?(' + src[t.PRERELEASEIDENTIFIERLOOSE] +
                       '(?:\\.' + src[t.PRERELEASEIDENTIFIERLOOSE] + ')*))'

// ## Build Metadata Identifier
// Any combination of digits, letters, or hyphens.

tok('BUILDIDENTIFIER')
src[t.BUILDIDENTIFIER] = LETTERDASHNUMBER + '+'

// ## Build Metadata
// Plus sign, followed by one or more period-separated build metadata
// identifiers.

tok('BUILD')
src[t.BUILD] = '(?:\\+(' + src[t.BUILDIDENTIFIER] +
             '(?:\\.' + src[t.BUILDIDENTIFIER] + ')*))'

// ## Full Version String
// A main version, followed optionally by a pre-release version and
// build metadata.

// Note that the only major, minor, patch, and pre-release sections of
// the version string are capturing groups.  The build metadata is not a
// capturing group, because it should not ever be used in version
// comparison.

tok('FULL')
tok('FULLPLAIN')
src[t.FULLPLAIN] = 'v?' + src[t.MAINVERSION] +
                  src[t.PRERELEASE] + '?' +
                  src[t.BUILD] + '?'

src[t.FULL] = '^' + src[t.FULLPLAIN] + '$'

// like full, but allows v1.2.3 and =1.2.3, which people do sometimes.
// also, 1.0.0alpha1 (prerelease without the hyphen) which is pretty
// common in the npm registry.
tok('LOOSEPLAIN')
src[t.LOOSEPLAIN] = '[v=\\s]*' + src[t.MAINVERSIONLOOSE] +
                  src[t.PRERELEASELOOSE] + '?' +
                  src[t.BUILD] + '?'

tok('LOOSE')
src[t.LOOSE] = '^' + src[t.LOOSEPLAIN] + '$'

tok('GTLT')
src[t.GTLT] = '((?:<|>)?=?)'

// Something like "2.*" or "1.2.x".
// Note that "x.x" is a valid xRange identifer, meaning "any version"
// Only the first item is strictly required.
tok('XRANGEIDENTIFIERLOOSE')
src[t.XRANGEIDENTIFIERLOOSE] = src[t.NUMERICIDENTIFIERLOOSE] + '|x|X|\\*'
tok('XRANGEIDENTIFIER')
src[t.XRANGEIDENTIFIER] = src[t.NUMERICIDENTIFIER] + '|x|X|\\*'

tok('XRANGEPLAIN')
src[t.XRANGEPLAIN] = '[v=\\s]*(' + src[t.XRANGEIDENTIFIER] + ')' +
                   '(?:\\.(' + src[t.XRANGEIDENTIFIER] + ')' +
                   '(?:\\.(' + src[t.XRANGEIDENTIFIER] + ')' +
                   '(?:' + src[t.PRERELEASE] + ')?' +
                   src[t.BUILD] + '?' +
                   ')?)?'

tok('XRANGEPLAINLOOSE')
src[t.XRANGEPLAINLOOSE] = '[v=\\s]*(' + src[t.XRANGEIDENTIFIERLOOSE] + ')' +
                        '(?:\\.(' + src[t.XRANGEIDENTIFIERLOOSE] + ')' +
                        '(?:\\.(' + src[t.XRANGEIDENTIFIERLOOSE] + ')' +
                        '(?:' + src[t.PRERELEASELOOSE] + ')?' +
                        src[t.BUILD] + '?' +
                        ')?)?'

tok('XRANGE')
src[t.XRANGE] = '^' + src[t.GTLT] + '\\s*' + src[t.XRANGEPLAIN] + '$'
tok('XRANGELOOSE')
src[t.XRANGELOOSE] = '^' + src[t.GTLT] + '\\s*' + src[t.XRANGEPLAINLOOSE] + '$'

// Coercion.
// Extract anything that could conceivably be a part of a valid semver
tok('COERCE')
src[t.COERCE] = '(^|[^\\d])' +
              '(\\d{1,' + MAX_SAFE_COMPONENT_LENGTH + '})' +
              '(?:\\.(\\d{1,' + MAX_SAFE_COMPONENT_LENGTH + '}))?' +
              '(?:\\.(\\d{1,' + MAX_SAFE_COMPONENT_LENGTH + '}))?' +
              '(?:$|[^\\d])'
tok('COERCERTL')
re[t.COERCERTL] = new RegExp(src[t.COERCE], 'g')
safeRe[t.COERCERTL] = new RegExp(makeSafeRe(src[t.COERCE]), 'g')

// Tilde ranges.
// Meaning is "reasonably at or greater than"
tok('LONETILDE')
src[t.LONETILDE] = '(?:~>?)'

tok('TILDETRIM')
src[t.TILDETRIM] = '(\\s*)' + src[t.LONETILDE] + '\\s+'
re[t.TILDETRIM] = new RegExp(src[t.TILDETRIM], 'g')
safeRe[t.TILDETRIM] = new RegExp(makeSafeRe(src[t.TILDETRIM]), 'g')
var tildeTrimReplace = '$1~'

tok('TILDE')
src[t.TILDE] = '^' + src[t.LONETILDE] + src[t.XRANGEPLAIN] + '$'
tok('TILDELOOSE')
src[t.TILDELOOSE] = '^' + src[t.LONETILDE] + src[t.XRANGEPLAINLOOSE] + '$'

// Caret ranges.
// Meaning is "at least and backwards compatible with"
tok('LONECARET')
src[t.LONECARET] = '(?:\\^)'

tok('CARETTRIM')
src[t.CARETTRIM] = '(\\s*)' + src[t.LONECARET] + '\\s+'
re[t.CARETTRIM] = new RegExp(src[t.CARETTRIM], 'g')
safeRe[t.CARETTRIM] = new RegExp(makeSafeRe(src[t.CARETTRIM]), 'g')
var caretTrimReplace = '$1^'

tok('CARET')
src[t.CARET] = '^' + src[t.LONECARET] + src[t.XRANGEPLAIN] + '$'
tok('CARETLOOSE')
src[t.CARETLOOSE] = '^' + src[t.LONECARET] + src[t.XRANGEPLAINLOOSE] + '$'

// A simple gt/lt/eq thing, or just "" to indicate "any version"
tok('COMPARATORLOOSE')
src[t.COMPARATORLOOSE] = '^' + src[t.GTLT] + '\\s*(' + src[t.LOOSEPLAIN] + ')$|^$'
tok('COMPARATOR')
src[t.COMPARATOR] = '^' + src[t.GTLT] + '\\s*(' + src[t.FULLPLAIN] + ')$|^$'

// An expression to strip any whitespace between the gtlt and the thing
// it modifies, so that `> 1.2.3` ==> `>1.2.3`
tok('COMPARATORTRIM')
src[t.COMPARATORTRIM] = '(\\s*)' + src[t.GTLT] +
                      '\\s*(' + src[t.LOOSEPLAIN] + '|' + src[t.XRANGEPLAIN] + ')'

// this one has to use the /g flag
re[t.COMPARATORTRIM] = new RegExp(src[t.COMPARATORTRIM], 'g')
safeRe[t.COMPARATORTRIM] = new RegExp(makeSafeRe(src[t.COMPARATORTRIM]), 'g')
var comparatorTrimReplace = '$1$2$3'

// Something like `1.2.3 - 1.2.4`
// Note that these all use the loose form, because they'll be
// checked against either the strict or loose comparator form
// later.
tok('HYPHENRANGE')
src[t.HYPHENRANGE] = '^\\s*(' + src[t.XRANGEPLAIN] + ')' +
                   '\\s+-\\s+' +
                   '(' + src[t.XRANGEPLAIN] + ')' +
                   '\\s*$'

tok('HYPHENRANGELOOSE')
src[t.HYPHENRANGELOOSE] = '^\\s*(' + src[t.XRANGEPLAINLOOSE] + ')' +
                        '\\s+-\\s+' +
                        '(' + src[t.XRANGEPLAINLOOSE] + ')' +
                        '\\s*$'

// Star ranges basically just allow anything at all.
tok('STAR')
src[t.STAR] = '(<|>)?=?\\s*\\*'

// Compile to actual regexp objects.
// All are flag-free, unless they were created above with a flag.
for (var i = 0; i < R; i++) {
  debug(i, src[i])
  if (!re[i]) {
    re[i] = new RegExp(src[i])

    // Replace all greedy whitespace to prevent regex dos issues. These regex are
    // used internally via the safeRe object since all inputs in this library get
    // normalized first to trim and collapse all extra whitespace. The original
    // regexes are exported for userland consumption and lower level usage. A
    // future breaking change could export the safer regex only with a note that
    // all input should have extra whitespace removed.
    safeRe[i] = new RegExp(makeSafeRe(src[i]))
  }
}

exports.parse = parse
function parse (version, options) {
  if (!options || typeof options !== 'object') {
    options = {
      loose: !!options,
      includePrerelease: false
    }
  }

  if (version instanceof SemVer) {
    return version
  }

  if (typeof version !== 'string') {
    return null
  }

  if (version.length > MAX_LENGTH) {
    return null
  }

  var r = options.loose ? safeRe[t.LOOSE] : safeRe[t.FULL]
  if (!r.test(version)) {
    return null
  }

  try {
    return new SemVer(version, options)
  } catch (er) {
    return null
  }
}

exports.valid = valid
function valid (version, options) {
  var v = parse(version, options)
  return v ? v.version : null
}

exports.clean = clean
function clean (version, options) {
  var s = parse(version.trim().replace(/^[=v]+/, ''), options)
  return s ? s.version : null
}

exports.SemVer = SemVer

function SemVer (version, options) {
  if (!options || typeof options !== 'object') {
    options = {
      loose: !!options,
      includePrerelease: false
    }
  }
  if (version instanceof SemVer) {
    if (version.loose === options.loose) {
      return version
    } else {
      version = version.version
    }
  } else if (typeof version !== 'string') {
    throw new TypeError('Invalid Version: ' + version)
  }

  if (version.length > MAX_LENGTH) {
    throw new TypeError('version is longer than ' + MAX_LENGTH + ' characters')
  }

  if (!(this instanceof SemVer)) {
    return new SemVer(version, options)
  }

  debug('SemVer', version, options)
  this.options = options
  this.loose = !!options.loose

  var m = version.trim().match(options.loose ? safeRe[t.LOOSE] : safeRe[t.FULL])

  if (!m) {
    throw new TypeError('Invalid Version: ' + version)
  }

  this.raw = version

  // these are actually numbers
  this.major = +m[1]
  this.minor = +m[2]
  this.patch = +m[3]

  if (this.major > MAX_SAFE_INTEGER || this.major < 0) {
    throw new TypeError('Invalid major version')
  }

  if (this.minor > MAX_SAFE_INTEGER || this.minor < 0) {
    throw new TypeError('Invalid minor version')
  }

  if (this.patch > MAX_SAFE_INTEGER || this.patch < 0) {
    throw new TypeError('Invalid patch version')
  }

  // numberify any prerelease numeric ids
  if (!m[4]) {
    this.prerelease = []
  } else {
    this.prerelease = m[4].split('.').map(function (id) {
      if (/^[0-9]+$/.test(id)) {
        var num = +id
        if (num >= 0 && num < MAX_SAFE_INTEGER) {
          return num
        }
      }
      return id
    })
  }

  this.build = m[5] ? m[5].split('.') : []
  this.format()
}

SemVer.prototype.format = function () {
  this.version = this.major + '.' + this.minor + '.' + this.patch
  if (this.prerelease.length) {
    this.version += '-' + this.prerelease.join('.')
  }
  return this.version
}

SemVer.prototype.toString = function () {
  return this.version
}

SemVer.prototype.compare = function (other) {
  debug('SemVer.compare', this.version, this.options, other)
  if (!(other instanceof SemVer)) {
    other = new SemVer(other, this.options)
  }

  return this.compareMain(other) || this.comparePre(other)
}

SemVer.prototype.compareMain = function (other) {
  if (!(other instanceof SemVer)) {
    other = new SemVer(other, this.options)
  }

  return compareIdentifiers(this.major, other.major) ||
         compareIdentifiers(this.minor, other.minor) ||
         compareIdentifiers(this.patch, other.patch)
}

SemVer.prototype.comparePre = function (other) {
  if (!(other instanceof SemVer)) {
    other = new SemVer(other, this.options)
  }

  // NOT having a prerelease is > having one
  if (this.prerelease.length && !other.prerelease.length) {
    return -1
  } else if (!this.prerelease.length && other.prerelease.length) {
    return 1
  } else if (!this.prerelease.length && !other.prerelease.length) {
    return 0
  }

  var i = 0
  do {
    var a = this.prerelease[i]
    var b = other.prerelease[i]
    debug('prerelease compare', i, a, b)
    if (a === undefined && b === undefined) {
      return 0
    } else if (b === undefined) {
      return 1
    } else if (a === undefined) {
      return -1
    } else if (a === b) {
      continue
    } else {
      return compareIdentifiers(a, b)
    }
  } while (++i)
}

SemVer.prototype.compareBuild = function (other) {
  if (!(other instanceof SemVer)) {
    other = new SemVer(other, this.options)
  }

  var i = 0
  do {
    var a = this.build[i]
    var b = other.build[i]
    debug('prerelease compare', i, a, b)
    if (a === undefined && b === undefined) {
      return 0
    } else if (b === undefined) {
      return 1
    } else if (a === undefined) {
      return -1
    } else if (a === b) {
      continue
    } else {
      return compareIdentifiers(a, b)
    }
  } while (++i)
}

// preminor will bump the version up to the next minor release, and immediately
// down to pre-release. premajor and prepatch work the same way.
SemVer.prototype.inc = function (release, identifier) {
  switch (release) {
    case 'premajor':
      this.prerelease.length = 0
      this.patch = 0
      this.minor = 0
      this.major++
      this.inc('pre', identifier)
      break
    case 'preminor':
      this.prerelease.length = 0
      this.patch = 0
      this.minor++
      this.inc('pre', identifier)
      break
    case 'prepatch':
      // If this is already a prerelease, it will bump to the next version
      // drop any prereleases that might already exist, since they are not
      // relevant at this point.
      this.prerelease.length = 0
      this.inc('patch', identifier)
      this.inc('pre', identifier)
      break
    // If the input is a non-prerelease version, this acts the same as
    // prepatch.
    case 'prerelease':
      if (this.prerelease.length === 0) {
        this.inc('patch', identifier)
      }
      this.inc('pre', identifier)
      break

    case 'major':
      // If this is a pre-major version, bump up to the same major version.
      // Otherwise increment major.
      // 1.0.0-5 bumps to 1.0.0
      // 1.1.0 bumps to 2.0.0
      if (this.minor !== 0 ||
          this.patch !== 0 ||
          this.prerelease.length === 0) {
        this.major++
      }
      this.minor = 0
      this.patch = 0
      this.prerelease = []
      break
    case 'minor':
      // If this is a pre-minor version, bump up to the same minor version.
      // Otherwise increment minor.
      // 1.2.0-5 bumps to 1.2.0
      // 1.2.1 bumps to 1.3.0
      if (this.patch !== 0 || this.prerelease.length === 0) {
        this.minor++
      }
      this.patch = 0
      this.prerelease = []
      break
    case 'patch':
      // If this is not a pre-release version, it will increment the patch.
      // If it is a pre-release it will bump up to the same patch version.
      // 1.2.0-5 patches to 1.2.0
      // 1.2.0 patches to 1.2.1
      if (this.prerelease.length === 0) {
        this.patch++
      }
      this.prerelease = []
      break
    // This probably shouldn't be used publicly.
    // 1.0.0 "pre" would become 1.0.0-0 which is the wrong direction.
    case 'pre':
      if (this.prerelease.length === 0) {
        this.prerelease = [0]
      } else {
        var i = this.prerelease.length
        while (--i >= 0) {
          if (typeof this.prerelease[i] === 'number') {
            this.prerelease[i]++
            i = -2
          }
        }
        if (i === -1) {
          // didn't increment anything
          this.prerelease.push(0)
        }
      }
      if (identifier) {
        // 1.2.0-beta.1 bumps to 1.2.0-beta.2,
        // 1.2.0-beta.fooblz or 1.2.0-beta bumps to 1.2.0-beta.0
        if (this.prerelease[0] === identifier) {
          if (isNaN(this.prerelease[1])) {
            this.prerelease = [identifier, 0]
          }
        } else {
          this.prerelease = [identifier, 0]
        }
      }
      break

    default:
      throw new Error('invalid increment argument: ' + release)
  }
  this.format()
  this.raw = this.version
  return this
}

exports.inc = inc
function inc (version, release, loose, identifier) {
  if (typeof (loose) === 'string') {
    identifier = loose
    loose = undefined
  }

  try {
    return new SemVer(version, loose).inc(release, identifier).version
  } catch (er) {
    return null
  }
}

exports.diff = diff
function diff (version1, version2) {
  if (eq(version1, version2)) {
    return null
  } else {
    var v1 = parse(version1)
    var v2 = parse(version2)
    var prefix = ''
    if (v1.prerelease.length || v2.prerelease.length) {
      prefix = 'pre'
      var defaultResult = 'prerelease'
    }
    for (var key in v1) {
      if (key === 'major' || key === 'minor' || key === 'patch') {
        if (v1[key] !== v2[key]) {
          return prefix + key
        }
      }
    }
    return defaultResult // may be undefined
  }
}

exports.compareIdentifiers = compareIdentifiers

var numeric = /^[0-9]+$/
function compareIdentifiers (a, b) {
  var anum = numeric.test(a)
  var bnum = numeric.test(b)

  if (anum && bnum) {
    a = +a
    b = +b
  }

  return a === b ? 0
    : (anum && !bnum) ? -1
    : (bnum && !anum) ? 1
    : a < b ? -1
    : 1
}

exports.rcompareIdentifiers = rcompareIdentifiers
function rcompareIdentifiers (a, b) {
  return compareIdentifiers(b, a)
}

exports.major = major
function major (a, loose) {
  return new SemVer(a, loose).major
}

exports.minor = minor
function minor (a, loose) {
  return new SemVer(a, loose).minor
}

exports.patch = patch
function patch (a, loose) {
  return new SemVer(a, loose).patch
}

exports.compare = compare
function compare (a, b, loose) {
  return new SemVer(a, loose).compare(new SemVer(b, loose))
}

exports.compareLoose = compareLoose
function compareLoose (a, b) {
  return compare(a, b, true)
}

exports.compareBuild = compareBuild
function compareBuild (a, b, loose) {
  var versionA = new SemVer(a, loose)
  var versionB = new SemVer(b, loose)
  return versionA.compare(versionB) || versionA.compareBuild(versionB)
}

exports.rcompare = rcompare
function rcompare (a, b, loose) {
  return compare(b, a, loose)
}

exports.sort = sort
function sort (list, loose) {
  return list.sort(function (a, b) {
    return exports.compareBuild(a, b, loose)
  })
}

exports.rsort = rsort
function rsort (list, loose) {
  return list.sort(function (a, b) {
    return exports.compareBuild(b, a, loose)
  })
}

exports.gt = gt
function gt (a, b, loose) {
  return compare(a, b, loose) > 0
}

exports.lt = lt
function lt (a, b, loose) {
  return compare(a, b, loose) < 0
}

exports.eq = eq
function eq (a, b, loose) {
  return compare(a, b, loose) === 0
}

exports.neq = neq
function neq (a, b, loose) {
  return compare(a, b, loose) !== 0
}

exports.gte = gte
function gte (a, b, loose) {
  return compare(a, b, loose) >= 0
}

exports.lte = lte
function lte (a, b, loose) {
  return compare(a, b, loose) <= 0
}

exports.cmp = cmp
function cmp (a, op, b, loose) {
  switch (op) {
    case '===':
      if (typeof a === 'object')
        a = a.version
      if (typeof b === 'object')
        b = b.version
      return a === b

    case '!==':
      if (typeof a === 'object')
        a = a.version
      if (typeof b === 'object')
        b = b.version
      return a !== b

    case '':
    case '=':
    case '==':
      return eq(a, b, loose)

    case '!=':
      return neq(a, b, loose)

    case '>':
      return gt(a, b, loose)

    case '>=':
      return gte(a, b, loose)

    case '<':
      return lt(a, b, loose)

    case '<=':
      return lte(a, b, loose)

    default:
      throw new TypeError('Invalid operator: ' + op)
  }
}

exports.Comparator = Comparator
function Comparator (comp, options) {
  if (!options || typeof options !== 'object') {
    options = {
      loose: !!options,
      includePrerelease: false
    }
  }

  if (comp instanceof Comparator) {
    if (comp.loose === !!options.loose) {
      return comp
    } else {
      comp = comp.value
    }
  }

  if (!(this instanceof Comparator)) {
    return new Comparator(comp, options)
  }

  comp = comp.trim().split(/\s+/).join(' ')
  debug('comparator', comp, options)
  this.options = options
  this.loose = !!options.loose
  this.parse(comp)

  if (this.semver === ANY) {
    this.value = ''
  } else {
    this.value = this.operator + this.semver.version
  }

  debug('comp', this)
}

var ANY = {}
Comparator.prototype.parse = function (comp) {
  var r = this.options.loose ? safeRe[t.COMPARATORLOOSE] : safeRe[t.COMPARATOR]
  var m = comp.match(r)

  if (!m) {
    throw new TypeError('Invalid comparator: ' + comp)
  }

  this.operator = m[1] !== undefined ? m[1] : ''
  if (this.operator === '=') {
    this.operator = ''
  }

  // if it literally is just '>' or '' then allow anything.
  if (!m[2]) {
    this.semver = ANY
  } else {
    this.semver = new SemVer(m[2], this.options.loose)
  }
}

Comparator.prototype.toString = function () {
  return this.value
}

Comparator.prototype.test = function (version) {
  debug('Comparator.test', version, this.options.loose)

  if (this.semver === ANY || version === ANY) {
    return true
  }

  if (typeof version === 'string') {
    try {
      version = new SemVer(version, this.options)
    } catch (er) {
      return false
    }
  }

  return cmp(version, this.operator, this.semver, this.options)
}

Comparator.prototype.intersects = function (comp, options) {
  if (!(comp instanceof Comparator)) {
    throw new TypeError('a Comparator is required')
  }

  if (!options || typeof options !== 'object') {
    options = {
      loose: !!options,
      includePrerelease: false
    }
  }

  var rangeTmp

  if (this.operator === '') {
    if (this.value === '') {
      return true
    }
    rangeTmp = new Range(comp.value, options)
    return satisfies(this.value, rangeTmp, options)
  } else if (comp.operator === '') {
    if (comp.value === '') {
      return true
    }
    rangeTmp = new Range(this.value, options)
    return satisfies(comp.semver, rangeTmp, options)
  }

  var sameDirectionIncreasing =
    (this.operator === '>=' || this.operator === '>') &&
    (comp.operator === '>=' || comp.operator === '>')
  var sameDirectionDecreasing =
    (this.operator === '<=' || this.operator === '<') &&
    (comp.operator === '<=' || comp.operator === '<')
  var sameSemVer = this.semver.version === comp.semver.version
  var differentDirectionsInclusive =
    (this.operator === '>=' || this.operator === '<=') &&
    (comp.operator === '>=' || comp.operator === '<=')
  var oppositeDirectionsLessThan =
    cmp(this.semver, '<', comp.semver, options) &&
    ((this.operator === '>=' || this.operator === '>') &&
    (comp.operator === '<=' || comp.operator === '<'))
  var oppositeDirectionsGreaterThan =
    cmp(this.semver, '>', comp.semver, options) &&
    ((this.operator === '<=' || this.operator === '<') &&
    (comp.operator === '>=' || comp.operator === '>'))

  return sameDirectionIncreasing || sameDirectionDecreasing ||
    (sameSemVer && differentDirectionsInclusive) ||
    oppositeDirectionsLessThan || oppositeDirectionsGreaterThan
}

exports.Range = Range
function Range (range, options) {
  if (!options || typeof options !== 'object') {
    options = {
      loose: !!options,
      includePrerelease: false
    }
  }

  if (range instanceof Range) {
    if (range.loose === !!options.loose &&
        range.includePrerelease === !!options.includePrerelease) {
      return range
    } else {
      return new Range(range.raw, options)
    }
  }

  if (range instanceof Comparator) {
    return new Range(range.value, options)
  }

  if (!(this instanceof Range)) {
    return new Range(range, options)
  }

  this.options = options
  this.loose = !!options.loose
  this.includePrerelease = !!options.includePrerelease

  // First reduce all whitespace as much as possible so we do not have to rely
  // on potentially slow regexes like \s*. This is then stored and used for
  // future error messages as well.
  this.raw = range
    .trim()
    .split(/\s+/)
    .join(' ')

  // First, split based on boolean or ||
  this.set = this.raw.split('||').map(function (range) {
    return this.parseRange(range.trim())
  }, this).filter(function (c) {
    // throw out any that are not relevant for whatever reason
    return c.length
  })

  if (!this.set.length) {
    throw new TypeError('Invalid SemVer Range: ' + this.raw)
  }

  this.format()
}

Range.prototype.format = function () {
  this.range = this.set.map(function (comps) {
    return comps.join(' ').trim()
  }).join('||').trim()
  return this.range
}

Range.prototype.toString = function () {
  return this.range
}

Range.prototype.parseRange = function (range) {
  var loose = this.options.loose
  // `1.2.3 - 1.2.4` => `>=1.2.3 <=1.2.4`
  var hr = loose ? safeRe[t.HYPHENRANGELOOSE] : safeRe[t.HYPHENRANGE]
  range = range.replace(hr, hyphenReplace)
  debug('hyphen replace', range)
  // `> 1.2.3 < 1.2.5` => `>1.2.3 <1.2.5`
  range = range.replace(safeRe[t.COMPARATORTRIM], comparatorTrimReplace)
  debug('comparator trim', range, safeRe[t.COMPARATORTRIM])

  // `~ 1.2.3` => `~1.2.3`
  range = range.replace(safeRe[t.TILDETRIM], tildeTrimReplace)

  // `^ 1.2.3` => `^1.2.3`
  range = range.replace(safeRe[t.CARETTRIM], caretTrimReplace)

  // normalize spaces
  range = range.split(/\s+/).join(' ')

  // At this point, the range is completely trimmed and
  // ready to be split into comparators.

  var compRe = loose ? safeRe[t.COMPARATORLOOSE] : safeRe[t.COMPARATOR]
  var set = range.split(' ').map(function (comp) {
    return parseComparator(comp, this.options)
  }, this).join(' ').split(/\s+/)
  if (this.options.loose) {
    // in loose mode, throw out any that are not valid comparators
    set = set.filter(function (comp) {
      return !!comp.match(compRe)
    })
  }
  set = set.map(function (comp) {
    return new Comparator(comp, this.options)
  }, this)

  return set
}

Range.prototype.intersects = function (range, options) {
  if (!(range instanceof Range)) {
    throw new TypeError('a Range is required')
  }

  return this.set.some(function (thisComparators) {
    return (
      isSatisfiable(thisComparators, options) &&
      range.set.some(function (rangeComparators) {
        return (
          isSatisfiable(rangeComparators, options) &&
          thisComparators.every(function (thisComparator) {
            return rangeComparators.every(function (rangeComparator) {
              return thisComparator.intersects(rangeComparator, options)
            })
          })
        )
      })
    )
  })
}

// take a set of comparators and determine whether there
// exists a version which can satisfy it
function isSatisfiable (comparators, options) {
  var result = true
  var remainingComparators = comparators.slice()
  var testComparator = remainingComparators.pop()

  while (result && remainingComparators.length) {
    result = remainingComparators.every(function (otherComparator) {
      return testComparator.intersects(otherComparator, options)
    })

    testComparator = remainingComparators.pop()
  }

  return result
}

// Mostly just for testing and legacy API reasons
exports.toComparators = toComparators
function toComparators (range, options) {
  return new Range(range, options).set.map(function (comp) {
    return comp.map(function (c) {
      return c.value
    }).join(' ').trim().split(' ')
  })
}

// comprised of xranges, tildes, stars, and gtlt's at this point.
// already replaced the hyphen ranges
// turn into a set of JUST comparators.
function parseComparator (comp, options) {
  debug('comp', comp, options)
  comp = replaceCarets(comp, options)
  debug('caret', comp)
  comp = replaceTildes(comp, options)
  debug('tildes', comp)
  comp = replaceXRanges(comp, options)
  debug('xrange', comp)
  comp = replaceStars(comp, options)
  debug('stars', comp)
  return comp
}

function isX (id) {
  return !id || id.toLowerCase() === 'x' || id === '*'
}

// ~, ~> --> * (any, kinda silly)
// ~2, ~2.x, ~2.x.x, ~>2, ~>2.x ~>2.x.x --> >=2.0.0 <3.0.0
// ~2.0, ~2.0.x, ~>2.0, ~>2.0.x --> >=2.0.0 <2.1.0
// ~1.2, ~1.2.x, ~>1.2, ~>1.2.x --> >=1.2.0 <1.3.0
// ~1.2.3, ~>1.2.3 --> >=1.2.3 <1.3.0
// ~1.2.0, ~>1.2.0 --> >=1.2.0 <1.3.0
function replaceTildes (comp, options) {
  return comp.trim().split(/\s+/).map(function (comp) {
    return replaceTilde(comp, options)
  }).join(' ')
}

function replaceTilde (comp, options) {
  var r = options.loose ? safeRe[t.TILDELOOSE] : safeRe[t.TILDE]
  return comp.replace(r, function (_, M, m, p, pr) {
    debug('tilde', comp, _, M, m, p, pr)
    var ret

    if (isX(M)) {
      ret = ''
    } else if (isX(m)) {
      ret = '>=' + M + '.0.0 <' + (+M + 1) + '.0.0'
    } else if (isX(p)) {
      // ~1.2 == >=1.2.0 <1.3.0
      ret = '>=' + M + '.' + m + '.0 <' + M + '.' + (+m + 1) + '.0'
    } else if (pr) {
      debug('replaceTilde pr', pr)
      ret = '>=' + M + '.' + m + '.' + p + '-' + pr +
            ' <' + M + '.' + (+m + 1) + '.0'
    } else {
      // ~1.2.3 == >=1.2.3 <1.3.0
      ret = '>=' + M + '.' + m + '.' + p +
            ' <' + M + '.' + (+m + 1) + '.0'
    }

    debug('tilde return', ret)
    return ret
  })
}

// ^ --> * (any, kinda silly)
// ^2, ^2.x, ^2.x.x --> >=2.0.0 <3.0.0
// ^2.0, ^2.0.x --> >=2.0.0 <3.0.0
// ^1.2, ^1.2.x --> >=1.2.0 <2.0.0
// ^1.2.3 --> >=1.2.3 <2.0.0
// ^1.2.0 --> >=1.2.0 <2.0.0
function replaceCarets (comp, options) {
  return comp.trim().split(/\s+/).map(function (comp) {
    return replaceCaret(comp, options)
  }).join(' ')
}

function replaceCaret (comp, options) {
  debug('caret', comp, options)
  var r = options.loose ? safeRe[t.CARETLOOSE] : safeRe[t.CARET]
  return comp.replace(r, function (_, M, m, p, pr) {
    debug('caret', comp, _, M, m, p, pr)
    var ret

    if (isX(M)) {
      ret = ''
    } else if (isX(m)) {
      ret = '>=' + M + '.0.0 <' + (+M + 1) + '.0.0'
    } else if (isX(p)) {
      if (M === '0') {
        ret = '>=' + M + '.' + m + '.0 <' + M + '.' + (+m + 1) + '.0'
      } else {
        ret = '>=' + M + '.' + m + '.0 <' + (+M + 1) + '.0.0'
      }
    } else if (pr) {
      debug('replaceCaret pr', pr)
      if (M === '0') {
        if (m === '0') {
          ret = '>=' + M + '.' + m + '.' + p + '-' + pr +
                ' <' + M + '.' + m + '.' + (+p + 1)
        } else {
          ret = '>=' + M + '.' + m + '.' + p + '-' + pr +
                ' <' + M + '.' + (+m + 1) + '.0'
        }
      } else {
        ret = '>=' + M + '.' + m + '.' + p + '-' + pr +
              ' <' + (+M + 1) + '.0.0'
      }
    } else {
      debug('no pr')
      if (M === '0') {
        if (m === '0') {
          ret = '>=' + M + '.' + m + '.' + p +
                ' <' + M + '.' + m + '.' + (+p + 1)
        } else {
          ret = '>=' + M + '.' + m + '.' + p +
                ' <' + M + '.' + (+m + 1) + '.0'
        }
      } else {
        ret = '>=' + M + '.' + m + '.' + p +
              ' <' + (+M + 1) + '.0.0'
      }
    }

    debug('caret return', ret)
    return ret
  })
}

function replaceXRanges (comp, options) {
  debug('replaceXRanges', comp, options)
  return comp.split(/\s+/).map(function (comp) {
    return replaceXRange(comp, options)
  }).join(' ')
}

function replaceXRange (comp, options) {
  comp = comp.trim()
  var r = options.loose ? safeRe[t.XRANGELOOSE] : safeRe[t.XRANGE]
  return comp.replace(r, function (ret, gtlt, M, m, p, pr) {
    debug('xRange', comp, ret, gtlt, M, m, p, pr)
    var xM = isX(M)
    var xm = xM || isX(m)
    var xp = xm || isX(p)
    var anyX = xp

    if (gtlt === '=' && anyX) {
      gtlt = ''
    }

    // if we're including prereleases in the match, then we need
    // to fix this to -0, the lowest possible prerelease value
    pr = options.includePrerelease ? '-0' : ''

    if (xM) {
      if (gtlt === '>' || gtlt === '<') {
        // nothing is allowed
        ret = '<0.0.0-0'
      } else {
        // nothing is forbidden
        ret = '*'
      }
    } else if (gtlt && anyX) {
      // we know patch is an x, because we have any x at all.
      // replace X with 0
      if (xm) {
        m = 0
      }
      p = 0

      if (gtlt === '>') {
        // >1 => >=2.0.0
        // >1.2 => >=1.3.0
        // >1.2.3 => >= 1.2.4
        gtlt = '>='
        if (xm) {
          M = +M + 1
          m = 0
          p = 0
        } else {
          m = +m + 1
          p = 0
        }
      } else if (gtlt === '<=') {
        // <=0.7.x is actually <0.8.0, since any 0.7.x should
        // pass.  Similarly, <=7.x is actually <8.0.0, etc.
        gtlt = '<'
        if (xm) {
          M = +M + 1
        } else {
          m = +m + 1
        }
      }

      ret = gtlt + M + '.' + m + '.' + p + pr
    } else if (xm) {
      ret = '>=' + M + '.0.0' + pr + ' <' + (+M + 1) + '.0.0' + pr
    } else if (xp) {
      ret = '>=' + M + '.' + m + '.0' + pr +
        ' <' + M + '.' + (+m + 1) + '.0' + pr
    }

    debug('xRange return', ret)

    return ret
  })
}

// Because * is AND-ed with everything else in the comparator,
// and '' means "any version", just remove the *s entirely.
function replaceStars (comp, options) {
  debug('replaceStars', comp, options)
  // Looseness is ignored here.  star is always as loose as it gets!
  return comp.trim().replace(safeRe[t.STAR], '')
}

// This function is passed to string.replace(re[t.HYPHENRANGE])
// M, m, patch, prerelease, build
// 1.2 - 3.4.5 => >=1.2.0 <=3.4.5
// 1.2.3 - 3.4 => >=1.2.0 <3.5.0 Any 3.4.x will do
// 1.2 - 3.4 => >=1.2.0 <3.5.0
function hyphenReplace ($0,
  from, fM, fm, fp, fpr, fb,
  to, tM, tm, tp, tpr, tb) {
  if (isX(fM)) {
    from = ''
  } else if (isX(fm)) {
    from = '>=' + fM + '.0.0'
  } else if (isX(fp)) {
    from = '>=' + fM + '.' + fm + '.0'
  } else {
    from = '>=' + from
  }

  if (isX(tM)) {
    to = ''
  } else if (isX(tm)) {
    to = '<' + (+tM + 1) + '.0.0'
  } else if (isX(tp)) {
    to = '<' + tM + '.' + (+tm + 1) + '.0'
  } else if (tpr) {
    to = '<=' + tM + '.' + tm + '.' + tp + '-' + tpr
  } else {
    to = '<=' + to
  }

  return (from + ' ' + to).trim()
}

// if ANY of the sets match ALL of its comparators, then pass
Range.prototype.test = function (version) {
  if (!version) {
    return false
  }

  if (typeof version === 'string') {
    try {
      version = new SemVer(version, this.options)
    } catch (er) {
      return false
    }
  }

  for (var i = 0; i < this.set.length; i++) {
    if (testSet(this.set[i], version, this.options)) {
      return true
    }
  }
  return false
}

function testSet (set, version, options) {
  for (var i = 0; i < set.length; i++) {
    if (!set[i].test(version)) {
      return false
    }
  }

  if (version.prerelease.length && !options.includePrerelease) {
    // Find the set of versions that are allowed to have prereleases
    // For example, ^1.2.3-pr.1 desugars to >=1.2.3-pr.1 <2.0.0
    // That should allow `1.2.3-pr.2` to pass.
    // However, `1.2.4-alpha.notready` should NOT be allowed,
    // even though it's within the range set by the comparators.
    for (i = 0; i < set.length; i++) {
      debug(set[i].semver)
      if (set[i].semver === ANY) {
        continue
      }

      if (set[i].semver.prerelease.length > 0) {
        var allowed = set[i].semver
        if (allowed.major === version.major &&
            allowed.minor === version.minor &&
            allowed.patch === version.patch) {
          return true
        }
      }
    }

    // Version has a -pre, but it's not one of the ones we like.
    return false
  }

  return true
}

exports.satisfies = satisfies
function satisfies (version, range, options) {
  try {
    range = new Range(range, options)
  } catch (er) {
    return false
  }
  return range.test(version)
}

exports.maxSatisfying = maxSatisfying
function maxSatisfying (versions, range, options) {
  var max = null
  var maxSV = null
  try {
    var rangeObj = new Range(range, options)
  } catch (er) {
    return null
  }
  versions.forEach(function (v) {
    if (rangeObj.test(v)) {
      // satisfies(v, range, options)
      if (!max || maxSV.compare(v) === -1) {
        // compare(max, v, true)
        max = v
        maxSV = new SemVer(max, options)
      }
    }
  })
  return max
}

exports.minSatisfying = minSatisfying
function minSatisfying (versions, range, options) {
  var min = null
  var minSV = null
  try {
    var rangeObj = new Range(range, options)
  } catch (er) {
    return null
  }
  versions.forEach(function (v) {
    if (rangeObj.test(v)) {
      // satisfies(v, range, options)
      if (!min || minSV.compare(v) === 1) {
        // compare(min, v, true)
        min = v
        minSV = new SemVer(min, options)
      }
    }
  })
  return min
}

exports.minVersion = minVersion
function minVersion (range, loose) {
  range = new Range(range, loose)

  var minver = new SemVer('0.0.0')
  if (range.test(minver)) {
    return minver
  }

  minver = new SemVer('0.0.0-0')
  if (range.test(minver)) {
    return minver
  }

  minver = null
  for (var i = 0; i < range.set.length; ++i) {
    var comparators = range.set[i]

    comparators.forEach(function (comparator) {
      // Clone to avoid manipulating the comparator's semver object.
      var compver = new SemVer(comparator.semver.version)
      switch (comparator.operator) {
        case '>':
          if (compver.prerelease.length === 0) {
            compver.patch++
          } else {
            compver.prerelease.push(0)
          }
          compver.raw = compver.format()
          /* fallthrough */
        case '':
        case '>=':
          if (!minver || gt(minver, compver)) {
            minver = compver
          }
          break
        case '<':
        case '<=':
          /* Ignore maximum versions */
          break
        /* istanbul ignore next */
        default:
          throw new Error('Unexpected operation: ' + comparator.operator)
      }
    })
  }

  if (minver && range.test(minver)) {
    return minver
  }

  return null
}

exports.validRange = validRange
function validRange (range, options) {
  try {
    // Return '*' instead of '' so that truthiness works.
    // This will throw if it's invalid anyway
    return new Range(range, options).range || '*'
  } catch (er) {
    return null
  }
}

// Determine if version is less than all the versions possible in the range
exports.ltr = ltr
function ltr (version, range, options) {
  return outside(version, range, '<', options)
}

// Determine if version is greater than all the versions possible in the range.
exports.gtr = gtr
function gtr (version, range, options) {
  return outside(version, range, '>', options)
}

exports.outside = outside
function outside (version, range, hilo, options) {
  version = new SemVer(version, options)
  range = new Range(range, options)

  var gtfn, ltefn, ltfn, comp, ecomp
  switch (hilo) {
    case '>':
      gtfn = gt
      ltefn = lte
      ltfn = lt
      comp = '>'
      ecomp = '>='
      break
    case '<':
      gtfn = lt
      ltefn = gte
      ltfn = gt
      comp = '<'
      ecomp = '<='
      break
    default:
      throw new TypeError('Must provide a hilo val of "<" or ">"')
  }

  // If it satisifes the range it is not outside
  if (satisfies(version, range, options)) {
    return false
  }

  // From now on, variable terms are as if we're in "gtr" mode.
  // but note that everything is flipped for the "ltr" function.

  for (var i = 0; i < range.set.length; ++i) {
    var comparators = range.set[i]

    var high = null
    var low = null

    comparators.forEach(function (comparator) {
      if (comparator.semver === ANY) {
        comparator = new Comparator('>=0.0.0')
      }
      high = high || comparator
      low = low || comparator
      if (gtfn(comparator.semver, high.semver, options)) {
        high = comparator
      } else if (ltfn(comparator.semver, low.semver, options)) {
        low = comparator
      }
    })

    // If the edge version comparator has a operator then our version
    // isn't outside it
    if (high.operator === comp || high.operator === ecomp) {
      return false
    }

    // If the lowest version comparator has an operator and our version
    // is less than it then it isn't higher than the range
    if ((!low.operator || low.operator === comp) &&
        ltefn(version, low.semver)) {
      return false
    } else if (low.operator === ecomp && ltfn(version, low.semver)) {
      return false
    }
  }
  return true
}

exports.prerelease = prerelease
function prerelease (version, options) {
  var parsed = parse(version, options)
  return (parsed && parsed.prerelease.length) ? parsed.prerelease : null
}

exports.intersects = intersects
function intersects (r1, r2, options) {
  r1 = new Range(r1, options)
  r2 = new Range(r2, options)
  return r1.intersects(r2)
}

exports.coerce = coerce
function coerce (version, options) {
  if (version instanceof SemVer) {
    return version
  }

  if (typeof version === 'number') {
    version = String(version)
  }

  if (typeof version !== 'string') {
    return null
  }

  options = options || {}

  var match = null
  if (!options.rtl) {
    match = version.match(safeRe[t.COERCE])
  } else {
    // Find the right-most coercible string that does not share
    // a terminus with a more left-ward coercible string.
    // Eg, '1.2.3.4' wants to coerce '2.3.4', not '3.4' or '4'
    //
    // Walk through the string checking with a /g regexp
    // Manually set the index so as to pick up overlapping matches.
    // Stop when we get a match that ends at the string end, since no
    // coercible string can be more right-ward without the same terminus.
    var next
    while ((next = safeRe[t.COERCERTL].exec(version)) &&
      (!match || match.index + match[0].length !== version.length)
    ) {
      if (!match ||
          next.index + next[0].length !== match.index + match[0].length) {
        match = next
      }
      safeRe[t.COERCERTL].lastIndex = next.index + next[1].length + next[2].length
    }
    // leave it in a clean state
    safeRe[t.COERCERTL].lastIndex = -1
  }

  if (match === null) {
    return null
  }

  return parse(match[2] +
    '.' + (match[3] || '0') +
    '.' + (match[4] || '0'), options)
}