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unified-ai-platform/node_modules/ssri/index.js

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+'use strict'
+
+const crypto = require('crypto')
+const MiniPass = require('minipass')
+
+const SPEC_ALGORITHMS = ['sha256', 'sha384', 'sha512']
+
+// TODO: this should really be a hardcoded list of algorithms we support,
+// rather than [a-z0-9].
+const BASE64_REGEX = /^[a-z0-9+/]+(?:=?=?)$/i
+const SRI_REGEX = /^([a-z0-9]+)-([^?]+)([?\S*]*)$/
+const STRICT_SRI_REGEX = /^([a-z0-9]+)-([A-Za-z0-9+/=]{44,88})(\?[\x21-\x7E]*)?$/
+const VCHAR_REGEX = /^[\x21-\x7E]+$/
+
+const defaultOpts = {
+  algorithms: ['sha512'],
+  error: false,
+  options: [],
+  pickAlgorithm: getPrioritizedHash,
+  sep: ' ',
+  single: false,
+  strict: false
+}
+
+const ssriOpts = (opts = {}) => ({ ...defaultOpts, ...opts })
+
+const getOptString = options => !options || !options.length
+  ? ''
+  : `?${options.join('?')}`
+
+const _onEnd = Symbol('_onEnd')
+const _getOptions = Symbol('_getOptions')
+class IntegrityStream extends MiniPass {
+  constructor (opts) {
+    super()
+    this.size = 0
+    this.opts = opts
+
+    // may be overridden later, but set now for class consistency
+    this[_getOptions]()
+
+    // options used for calculating stream.  can't be changed.
+    const { algorithms = defaultOpts.algorithms } = opts
+    this.algorithms = Array.from(
+      new Set(algorithms.concat(this.algorithm ? [this.algorithm] : []))
+    )
+    this.hashes = this.algorithms.map(crypto.createHash)
+  }
+
+  [_getOptions] () {
+    const {
+      integrity,
+      size,
+      options
+    } = { ...defaultOpts, ...this.opts }
+
+    // For verification
+    this.sri = integrity ? parse(integrity, this.opts) : null
+    this.expectedSize = size
+    this.goodSri = this.sri ? !!Object.keys(this.sri).length : false
+    this.algorithm = this.goodSri ? this.sri.pickAlgorithm(this.opts) : null
+    this.digests = this.goodSri ? this.sri[this.algorithm] : null
+    this.optString = getOptString(options)
+  }
+
+  emit (ev, data) {
+    if (ev === 'end') this[_onEnd]()
+    return super.emit(ev, data)
+  }
+
+  write (data) {
+    this.size += data.length
+    this.hashes.forEach(h => h.update(data))
+    return super.write(data)
+  }
+
+  [_onEnd] () {
+    if (!this.goodSri) {
+      this[_getOptions]()
+    }
+    const newSri = parse(this.hashes.map((h, i) => {
+      return `${this.algorithms[i]}-${h.digest('base64')}${this.optString}`
+    }).join(' '), this.opts)
+    // Integrity verification mode
+    const match = this.goodSri && newSri.match(this.sri, this.opts)
+    if (typeof this.expectedSize === 'number' && this.size !== this.expectedSize) {
+      const err = new Error(`stream size mismatch when checking ${this.sri}.\n  Wanted: ${this.expectedSize}\n  Found: ${this.size}`)
+      err.code = 'EBADSIZE'
+      err.found = this.size
+      err.expected = this.expectedSize
+      err.sri = this.sri
+      this.emit('error', err)
+    } else if (this.sri && !match) {
+      const err = new Error(`${this.sri} integrity checksum failed when using ${this.algorithm}: wanted ${this.digests} but got ${newSri}. (${this.size} bytes)`)
+      err.code = 'EINTEGRITY'
+      err.found = newSri
+      err.expected = this.digests
+      err.algorithm = this.algorithm
+      err.sri = this.sri
+      this.emit('error', err)
+    } else {
+      this.emit('size', this.size)
+      this.emit('integrity', newSri)
+      match && this.emit('verified', match)
+    }
+  }
+}
+
+class Hash {
+  get isHash () { return true }
+  constructor (hash, opts) {
+    opts = ssriOpts(opts)
+    const strict = !!opts.strict
+    this.source = hash.trim()
+
+    // set default values so that we make V8 happy to
+    // always see a familiar object template.
+    this.digest = ''
+    this.algorithm = ''
+    this.options = []
+
+    // 3.1. Integrity metadata (called "Hash" by ssri)
+    // https://w3c.github.io/webappsec-subresource-integrity/#integrity-metadata-description
+    const match = this.source.match(
+      strict
+        ? STRICT_SRI_REGEX
+        : SRI_REGEX
+    )
+    if (!match) { return }
+    if (strict && !SPEC_ALGORITHMS.some(a => a === match[1])) { return }
+    this.algorithm = match[1]
+    this.digest = match[2]
+
+    const rawOpts = match[3]
+    if (rawOpts) {
+      this.options = rawOpts.slice(1).split('?')
+    }
+  }
+
+  hexDigest () {
+    return this.digest && Buffer.from(this.digest, 'base64').toString('hex')
+  }
+
+  toJSON () {
+    return this.toString()
+  }
+
+  toString (opts) {
+    opts = ssriOpts(opts)
+    if (opts.strict) {
+      // Strict mode enforces the standard as close to the foot of the
+      // letter as it can.
+      if (!(
+        // The spec has very restricted productions for algorithms.
+        // https://www.w3.org/TR/CSP2/#source-list-syntax
+        SPEC_ALGORITHMS.some(x => x === this.algorithm) &&
+        // Usually, if someone insists on using a "different" base64, we
+        // leave it as-is, since there's multiple standards, and the
+        // specified is not a URL-safe variant.
+        // https://www.w3.org/TR/CSP2/#base64_value
+        this.digest.match(BASE64_REGEX) &&
+        // Option syntax is strictly visual chars.
+        // https://w3c.github.io/webappsec-subresource-integrity/#grammardef-option-expression
+        // https://tools.ietf.org/html/rfc5234#appendix-B.1
+        this.options.every(opt => opt.match(VCHAR_REGEX))
+      )) {
+        return ''
+      }
+    }
+    const options = this.options && this.options.length
+      ? `?${this.options.join('?')}`
+      : ''
+    return `${this.algorithm}-${this.digest}${options}`
+  }
+}
+
+class Integrity {
+  get isIntegrity () { return true }
+  toJSON () {
+    return this.toString()
+  }
+
+  isEmpty () {
+    return Object.keys(this).length === 0
+  }
+
+  toString (opts) {
+    opts = ssriOpts(opts)
+    let sep = opts.sep || ' '
+    if (opts.strict) {
+      // Entries must be separated by whitespace, according to spec.
+      sep = sep.replace(/\S+/g, ' ')
+    }
+    return Object.keys(this).map(k => {
+      return this[k].map(hash => {
+        return Hash.prototype.toString.call(hash, opts)
+      }).filter(x => x.length).join(sep)
+    }).filter(x => x.length).join(sep)
+  }
+
+  concat (integrity, opts) {
+    opts = ssriOpts(opts)
+    const other = typeof integrity === 'string'
+      ? integrity
+      : stringify(integrity, opts)
+    return parse(`${this.toString(opts)} ${other}`, opts)
+  }
+
+  hexDigest () {
+    return parse(this, { single: true }).hexDigest()
+  }
+
+  // add additional hashes to an integrity value, but prevent
+  // *changing* an existing integrity hash.
+  merge (integrity, opts) {
+    opts = ssriOpts(opts)
+    const other = parse(integrity, opts)
+    for (const algo in other) {
+      if (this[algo]) {
+        if (!this[algo].find(hash =>
+          other[algo].find(otherhash =>
+            hash.digest === otherhash.digest))) {
+          throw new Error('hashes do not match, cannot update integrity')
+        }
+      } else {
+        this[algo] = other[algo]
+      }
+    }
+  }
+
+  match (integrity, opts) {
+    opts = ssriOpts(opts)
+    const other = parse(integrity, opts)
+    const algo = other.pickAlgorithm(opts)
+    return (
+      this[algo] &&
+      other[algo] &&
+      this[algo].find(hash =>
+        other[algo].find(otherhash =>
+          hash.digest === otherhash.digest
+        )
+      )
+    ) || false
+  }
+
+  pickAlgorithm (opts) {
+    opts = ssriOpts(opts)
+    const pickAlgorithm = opts.pickAlgorithm
+    const keys = Object.keys(this)
+    return keys.reduce((acc, algo) => {
+      return pickAlgorithm(acc, algo) || acc
+    })
+  }
+}
+
+module.exports.parse = parse
+function parse (sri, opts) {
+  if (!sri) return null
+  opts = ssriOpts(opts)
+  if (typeof sri === 'string') {
+    return _parse(sri, opts)
+  } else if (sri.algorithm && sri.digest) {
+    const fullSri = new Integrity()
+    fullSri[sri.algorithm] = [sri]
+    return _parse(stringify(fullSri, opts), opts)
+  } else {
+    return _parse(stringify(sri, opts), opts)
+  }
+}
+
+function _parse (integrity, opts) {
+  // 3.4.3. Parse metadata
+  // https://w3c.github.io/webappsec-subresource-integrity/#parse-metadata
+  if (opts.single) {
+    return new Hash(integrity, opts)
+  }
+  const hashes = integrity.trim().split(/\s+/).reduce((acc, string) => {
+    const hash = new Hash(string, opts)
+    if (hash.algorithm && hash.digest) {
+      const algo = hash.algorithm
+      if (!acc[algo]) { acc[algo] = [] }
+      acc[algo].push(hash)
+    }
+    return acc
+  }, new Integrity())
+  return hashes.isEmpty() ? null : hashes
+}
+
+module.exports.stringify = stringify
+function stringify (obj, opts) {
+  opts = ssriOpts(opts)
+  if (obj.algorithm && obj.digest) {
+    return Hash.prototype.toString.call(obj, opts)
+  } else if (typeof obj === 'string') {
+    return stringify(parse(obj, opts), opts)
+  } else {
+    return Integrity.prototype.toString.call(obj, opts)
+  }
+}
+
+module.exports.fromHex = fromHex
+function fromHex (hexDigest, algorithm, opts) {
+  opts = ssriOpts(opts)
+  const optString = getOptString(opts.options)
+  return parse(
+    `${algorithm}-${
+      Buffer.from(hexDigest, 'hex').toString('base64')
+    }${optString}`, opts
+  )
+}
+
+module.exports.fromData = fromData
+function fromData (data, opts) {
+  opts = ssriOpts(opts)
+  const algorithms = opts.algorithms
+  const optString = getOptString(opts.options)
+  return algorithms.reduce((acc, algo) => {
+    const digest = crypto.createHash(algo).update(data).digest('base64')
+    const hash = new Hash(
+      `${algo}-${digest}${optString}`,
+      opts
+    )
+    /* istanbul ignore else - it would be VERY strange if the string we
+     * just calculated with an algo did not have an algo or digest.
+     */
+    if (hash.algorithm && hash.digest) {
+      const algo = hash.algorithm
+      if (!acc[algo]) { acc[algo] = [] }
+      acc[algo].push(hash)
+    }
+    return acc
+  }, new Integrity())
+}
+
+module.exports.fromStream = fromStream
+function fromStream (stream, opts) {
+  opts = ssriOpts(opts)
+  const istream = integrityStream(opts)
+  return new Promise((resolve, reject) => {
+    stream.pipe(istream)
+    stream.on('error', reject)
+    istream.on('error', reject)
+    let sri
+    istream.on('integrity', s => { sri = s })
+    istream.on('end', () => resolve(sri))
+    istream.on('data', () => {})
+  })
+}
+
+module.exports.checkData = checkData
+function checkData (data, sri, opts) {
+  opts = ssriOpts(opts)
+  sri = parse(sri, opts)
+  if (!sri || !Object.keys(sri).length) {
+    if (opts.error) {
+      throw Object.assign(
+        new Error('No valid integrity hashes to check against'), {
+          code: 'EINTEGRITY'
+        }
+      )
+    } else {
+      return false
+    }
+  }
+  const algorithm = sri.pickAlgorithm(opts)
+  const digest = crypto.createHash(algorithm).update(data).digest('base64')
+  const newSri = parse({ algorithm, digest })
+  const match = newSri.match(sri, opts)
+  if (match || !opts.error) {
+    return match
+  } else if (typeof opts.size === 'number' && (data.length !== opts.size)) {
+    const err = new Error(`data size mismatch when checking ${sri}.\n  Wanted: ${opts.size}\n  Found: ${data.length}`)
+    err.code = 'EBADSIZE'
+    err.found = data.length
+    err.expected = opts.size
+    err.sri = sri
+    throw err
+  } else {
+    const err = new Error(`Integrity checksum failed when using ${algorithm}: Wanted ${sri}, but got ${newSri}. (${data.length} bytes)`)
+    err.code = 'EINTEGRITY'
+    err.found = newSri
+    err.expected = sri
+    err.algorithm = algorithm
+    err.sri = sri
+    throw err
+  }
+}
+
+module.exports.checkStream = checkStream
+function checkStream (stream, sri, opts) {
+  opts = ssriOpts(opts)
+  opts.integrity = sri
+  sri = parse(sri, opts)
+  if (!sri || !Object.keys(sri).length) {
+    return Promise.reject(Object.assign(
+      new Error('No valid integrity hashes to check against'), {
+        code: 'EINTEGRITY'
+      }
+    ))
+  }
+  const checker = integrityStream(opts)
+  return new Promise((resolve, reject) => {
+    stream.pipe(checker)
+    stream.on('error', reject)
+    checker.on('error', reject)
+    let sri
+    checker.on('verified', s => { sri = s })
+    checker.on('end', () => resolve(sri))
+    checker.on('data', () => {})
+  })
+}
+
+module.exports.integrityStream = integrityStream
+function integrityStream (opts = {}) {
+  return new IntegrityStream(opts)
+}
+
+module.exports.create = createIntegrity
+function createIntegrity (opts) {
+  opts = ssriOpts(opts)
+  const algorithms = opts.algorithms
+  const optString = getOptString(opts.options)
+
+  const hashes = algorithms.map(crypto.createHash)
+
+  return {
+    update: function (chunk, enc) {
+      hashes.forEach(h => h.update(chunk, enc))
+      return this
+    },
+    digest: function (enc) {
+      const integrity = algorithms.reduce((acc, algo) => {
+        const digest = hashes.shift().digest('base64')
+        const hash = new Hash(
+          `${algo}-${digest}${optString}`,
+          opts
+        )
+        /* istanbul ignore else - it would be VERY strange if the hash we
+         * just calculated with an algo did not have an algo or digest.
+         */
+        if (hash.algorithm && hash.digest) {
+          const algo = hash.algorithm
+          if (!acc[algo]) { acc[algo] = [] }
+          acc[algo].push(hash)
+        }
+        return acc
+      }, new Integrity())
+
+      return integrity
+    }
+  }
+}
+
+const NODE_HASHES = new Set(crypto.getHashes())
+
+// This is a Best Effort™ at a reasonable priority for hash algos
+const DEFAULT_PRIORITY = [
+  'md5', 'whirlpool', 'sha1', 'sha224', 'sha256', 'sha384', 'sha512',
+  // TODO - it's unclear _which_ of these Node will actually use as its name
+  //        for the algorithm, so we guesswork it based on the OpenSSL names.
+  'sha3',
+  'sha3-256', 'sha3-384', 'sha3-512',
+  'sha3_256', 'sha3_384', 'sha3_512'
+].filter(algo => NODE_HASHES.has(algo))
+
+function getPrioritizedHash (algo1, algo2) {
+  return DEFAULT_PRIORITY.indexOf(algo1.toLowerCase()) >= DEFAULT_PRIORITY.indexOf(algo2.toLowerCase())
+    ? algo1
+    : algo2
+}

unified-ai-platform/node_modules/ssri/node_modules/minipass/LICENSE

@@ -0,0 +1,15 @@
+The ISC License
+
+Copyright (c) 2017-2022 npm, Inc., Isaac Z. Schlueter, and Contributors
+
+Permission to use, copy, modify, and/or distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
+IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

unified-ai-platform/node_modules/ssri/node_modules/minipass/index.js

@@ -0,0 +1,649 @@
+'use strict'
+const proc = typeof process === 'object' && process ? process : {
+  stdout: null,
+  stderr: null,
+}
+const EE = require('events')
+const Stream = require('stream')
+const SD = require('string_decoder').StringDecoder
+
+const EOF = Symbol('EOF')
+const MAYBE_EMIT_END = Symbol('maybeEmitEnd')
+const EMITTED_END = Symbol('emittedEnd')
+const EMITTING_END = Symbol('emittingEnd')
+const EMITTED_ERROR = Symbol('emittedError')
+const CLOSED = Symbol('closed')
+const READ = Symbol('read')
+const FLUSH = Symbol('flush')
+const FLUSHCHUNK = Symbol('flushChunk')
+const ENCODING = Symbol('encoding')
+const DECODER = Symbol('decoder')
+const FLOWING = Symbol('flowing')
+const PAUSED = Symbol('paused')
+const RESUME = Symbol('resume')
+const BUFFERLENGTH = Symbol('bufferLength')
+const BUFFERPUSH = Symbol('bufferPush')
+const BUFFERSHIFT = Symbol('bufferShift')
+const OBJECTMODE = Symbol('objectMode')
+const DESTROYED = Symbol('destroyed')
+const EMITDATA = Symbol('emitData')
+const EMITEND = Symbol('emitEnd')
+const EMITEND2 = Symbol('emitEnd2')
+const ASYNC = Symbol('async')
+
+const defer = fn => Promise.resolve().then(fn)
+
+// TODO remove when Node v8 support drops
+const doIter = global._MP_NO_ITERATOR_SYMBOLS_  !== '1'
+const ASYNCITERATOR = doIter && Symbol.asyncIterator
+  || Symbol('asyncIterator not implemented')
+const ITERATOR = doIter && Symbol.iterator
+  || Symbol('iterator not implemented')
+
+// events that mean 'the stream is over'
+// these are treated specially, and re-emitted
+// if they are listened for after emitting.
+const isEndish = ev =>
+  ev === 'end' ||
+  ev === 'finish' ||
+  ev === 'prefinish'
+
+const isArrayBuffer = b => b instanceof ArrayBuffer ||
+  typeof b === 'object' &&
+  b.constructor &&
+  b.constructor.name === 'ArrayBuffer' &&
+  b.byteLength >= 0
+
+const isArrayBufferView = b => !Buffer.isBuffer(b) && ArrayBuffer.isView(b)
+
+class Pipe {
+  constructor (src, dest, opts) {
+    this.src = src
+    this.dest = dest
+    this.opts = opts
+    this.ondrain = () => src[RESUME]()
+    dest.on('drain', this.ondrain)
+  }
+  unpipe () {
+    this.dest.removeListener('drain', this.ondrain)
+  }
+  // istanbul ignore next - only here for the prototype
+  proxyErrors () {}
+  end () {
+    this.unpipe()
+    if (this.opts.end)
+      this.dest.end()
+  }
+}
+
+class PipeProxyErrors extends Pipe {
+  unpipe () {
+    this.src.removeListener('error', this.proxyErrors)
+    super.unpipe()
+  }
+  constructor (src, dest, opts) {
+    super(src, dest, opts)
+    this.proxyErrors = er => dest.emit('error', er)
+    src.on('error', this.proxyErrors)
+  }
+}
+
+module.exports = class Minipass extends Stream {
+  constructor (options) {
+    super()
+    this[FLOWING] = false
+    // whether we're explicitly paused
+    this[PAUSED] = false
+    this.pipes = []
+    this.buffer = []
+    this[OBJECTMODE] = options && options.objectMode || false
+    if (this[OBJECTMODE])
+      this[ENCODING] = null
+    else
+      this[ENCODING] = options && options.encoding || null
+    if (this[ENCODING] === 'buffer')
+      this[ENCODING] = null
+    this[ASYNC] = options && !!options.async || false
+    this[DECODER] = this[ENCODING] ? new SD(this[ENCODING]) : null
+    this[EOF] = false
+    this[EMITTED_END] = false
+    this[EMITTING_END] = false
+    this[CLOSED] = false
+    this[EMITTED_ERROR] = null
+    this.writable = true
+    this.readable = true
+    this[BUFFERLENGTH] = 0
+    this[DESTROYED] = false
+  }
+
+  get bufferLength () { return this[BUFFERLENGTH] }
+
+  get encoding () { return this[ENCODING] }
+  set encoding (enc) {
+    if (this[OBJECTMODE])
+      throw new Error('cannot set encoding in objectMode')
+
+    if (this[ENCODING] && enc !== this[ENCODING] &&
+        (this[DECODER] && this[DECODER].lastNeed || this[BUFFERLENGTH]))
+      throw new Error('cannot change encoding')
+
+    if (this[ENCODING] !== enc) {
+      this[DECODER] = enc ? new SD(enc) : null
+      if (this.buffer.length)
+        this.buffer = this.buffer.map(chunk => this[DECODER].write(chunk))
+    }
+
+    this[ENCODING] = enc
+  }
+
+  setEncoding (enc) {
+    this.encoding = enc
+  }
+
+  get objectMode () { return this[OBJECTMODE] }
+  set objectMode (om) { this[OBJECTMODE] = this[OBJECTMODE] || !!om }
+
+  get ['async'] () { return this[ASYNC] }
+  set ['async'] (a) { this[ASYNC] = this[ASYNC] || !!a }
+
+  write (chunk, encoding, cb) {
+    if (this[EOF])
+      throw new Error('write after end')
+
+    if (this[DESTROYED]) {
+      this.emit('error', Object.assign(
+        new Error('Cannot call write after a stream was destroyed'),
+        { code: 'ERR_STREAM_DESTROYED' }
+      ))
+      return true
+    }
+
+    if (typeof encoding === 'function')
+      cb = encoding, encoding = 'utf8'
+
+    if (!encoding)
+      encoding = 'utf8'
+
+    const fn = this[ASYNC] ? defer : f => f()
+
+    // convert array buffers and typed array views into buffers
+    // at some point in the future, we may want to do the opposite!
+    // leave strings and buffers as-is
+    // anything else switches us into object mode
+    if (!this[OBJECTMODE] && !Buffer.isBuffer(chunk)) {
+      if (isArrayBufferView(chunk))
+        chunk = Buffer.from(chunk.buffer, chunk.byteOffset, chunk.byteLength)
+      else if (isArrayBuffer(chunk))
+        chunk = Buffer.from(chunk)
+      else if (typeof chunk !== 'string')
+        // use the setter so we throw if we have encoding set
+        this.objectMode = true
+    }
+
+    // handle object mode up front, since it's simpler
+    // this yields better performance, fewer checks later.
+    if (this[OBJECTMODE]) {
+      /* istanbul ignore if - maybe impossible? */
+      if (this.flowing && this[BUFFERLENGTH] !== 0)
+        this[FLUSH](true)
+
+      if (this.flowing)
+        this.emit('data', chunk)
+      else
+        this[BUFFERPUSH](chunk)
+
+      if (this[BUFFERLENGTH] !== 0)
+        this.emit('readable')
+
+      if (cb)
+        fn(cb)
+
+      return this.flowing
+    }
+
+    // at this point the chunk is a buffer or string
+    // don't buffer it up or send it to the decoder
+    if (!chunk.length) {
+      if (this[BUFFERLENGTH] !== 0)
+        this.emit('readable')
+      if (cb)
+        fn(cb)
+      return this.flowing
+    }
+
+    // fast-path writing strings of same encoding to a stream with
+    // an empty buffer, skipping the buffer/decoder dance
+    if (typeof chunk === 'string' &&
+        // unless it is a string already ready for us to use
+        !(encoding === this[ENCODING] && !this[DECODER].lastNeed)) {
+      chunk = Buffer.from(chunk, encoding)
+    }
+
+    if (Buffer.isBuffer(chunk) && this[ENCODING])
+      chunk = this[DECODER].write(chunk)
+
+    // Note: flushing CAN potentially switch us into not-flowing mode
+    if (this.flowing && this[BUFFERLENGTH] !== 0)
+      this[FLUSH](true)
+
+    if (this.flowing)
+      this.emit('data', chunk)
+    else
+      this[BUFFERPUSH](chunk)
+
+    if (this[BUFFERLENGTH] !== 0)
+      this.emit('readable')
+
+    if (cb)
+      fn(cb)
+
+    return this.flowing
+  }
+
+  read (n) {
+    if (this[DESTROYED])
+      return null
+
+    if (this[BUFFERLENGTH] === 0 || n === 0 || n > this[BUFFERLENGTH]) {
+      this[MAYBE_EMIT_END]()
+      return null
+    }
+
+    if (this[OBJECTMODE])
+      n = null
+
+    if (this.buffer.length > 1 && !this[OBJECTMODE]) {
+      if (this.encoding)
+        this.buffer = [this.buffer.join('')]
+      else
+        this.buffer = [Buffer.concat(this.buffer, this[BUFFERLENGTH])]
+    }
+
+    const ret = this[READ](n || null, this.buffer[0])
+    this[MAYBE_EMIT_END]()
+    return ret
+  }
+
+  [READ] (n, chunk) {
+    if (n === chunk.length || n === null)
+      this[BUFFERSHIFT]()
+    else {
+      this.buffer[0] = chunk.slice(n)
+      chunk = chunk.slice(0, n)
+      this[BUFFERLENGTH] -= n
+    }
+
+    this.emit('data', chunk)
+
+    if (!this.buffer.length && !this[EOF])
+      this.emit('drain')
+
+    return chunk
+  }
+
+  end (chunk, encoding, cb) {
+    if (typeof chunk === 'function')
+      cb = chunk, chunk = null
+    if (typeof encoding === 'function')
+      cb = encoding, encoding = 'utf8'
+    if (chunk)
+      this.write(chunk, encoding)
+    if (cb)
+      this.once('end', cb)
+    this[EOF] = true
+    this.writable = false
+
+    // if we haven't written anything, then go ahead and emit,
+    // even if we're not reading.
+    // we'll re-emit if a new 'end' listener is added anyway.
+    // This makes MP more suitable to write-only use cases.
+    if (this.flowing || !this[PAUSED])
+      this[MAYBE_EMIT_END]()
+    return this
+  }
+
+  // don't let the internal resume be overwritten
+  [RESUME] () {
+    if (this[DESTROYED])
+      return
+
+    this[PAUSED] = false
+    this[FLOWING] = true
+    this.emit('resume')
+    if (this.buffer.length)
+      this[FLUSH]()
+    else if (this[EOF])
+      this[MAYBE_EMIT_END]()
+    else
+      this.emit('drain')
+  }
+
+  resume () {
+    return this[RESUME]()
+  }
+
+  pause () {
+    this[FLOWING] = false
+    this[PAUSED] = true
+  }
+
+  get destroyed () {
+    return this[DESTROYED]
+  }
+
+  get flowing () {
+    return this[FLOWING]
+  }
+
+  get paused () {
+    return this[PAUSED]
+  }
+
+  [BUFFERPUSH] (chunk) {
+    if (this[OBJECTMODE])
+      this[BUFFERLENGTH] += 1
+    else
+      this[BUFFERLENGTH] += chunk.length
+    this.buffer.push(chunk)
+  }
+
+  [BUFFERSHIFT] () {
+    if (this.buffer.length) {
+      if (this[OBJECTMODE])
+        this[BUFFERLENGTH] -= 1
+      else
+        this[BUFFERLENGTH] -= this.buffer[0].length
+    }
+    return this.buffer.shift()
+  }
+
+  [FLUSH] (noDrain) {
+    do {} while (this[FLUSHCHUNK](this[BUFFERSHIFT]()))
+
+    if (!noDrain && !this.buffer.length && !this[EOF])
+      this.emit('drain')
+  }
+
+  [FLUSHCHUNK] (chunk) {
+    return chunk ? (this.emit('data', chunk), this.flowing) : false
+  }
+
+  pipe (dest, opts) {
+    if (this[DESTROYED])
+      return
+
+    const ended = this[EMITTED_END]
+    opts = opts || {}
+    if (dest === proc.stdout || dest === proc.stderr)
+      opts.end = false
+    else
+      opts.end = opts.end !== false
+    opts.proxyErrors = !!opts.proxyErrors
+
+    // piping an ended stream ends immediately
+    if (ended) {
+      if (opts.end)
+        dest.end()
+    } else {
+      this.pipes.push(!opts.proxyErrors ? new Pipe(this, dest, opts)
+        : new PipeProxyErrors(this, dest, opts))
+      if (this[ASYNC])
+        defer(() => this[RESUME]())
+      else
+        this[RESUME]()
+    }
+
+    return dest
+  }
+
+  unpipe (dest) {
+    const p = this.pipes.find(p => p.dest === dest)
+    if (p) {
+      this.pipes.splice(this.pipes.indexOf(p), 1)
+      p.unpipe()
+    }
+  }
+
+  addListener (ev, fn) {
+    return this.on(ev, fn)
+  }
+
+  on (ev, fn) {
+    const ret = super.on(ev, fn)
+    if (ev === 'data' && !this.pipes.length && !this.flowing)
+      this[RESUME]()
+    else if (ev === 'readable' && this[BUFFERLENGTH] !== 0)
+      super.emit('readable')
+    else if (isEndish(ev) && this[EMITTED_END]) {
+      super.emit(ev)
+      this.removeAllListeners(ev)
+    } else if (ev === 'error' && this[EMITTED_ERROR]) {
+      if (this[ASYNC])
+        defer(() => fn.call(this, this[EMITTED_ERROR]))
+      else
+        fn.call(this, this[EMITTED_ERROR])
+    }
+    return ret
+  }
+
+  get emittedEnd () {
+    return this[EMITTED_END]
+  }
+
+  [MAYBE_EMIT_END] () {
+    if (!this[EMITTING_END] &&
+        !this[EMITTED_END] &&
+        !this[DESTROYED] &&
+        this.buffer.length === 0 &&
+        this[EOF]) {
+      this[EMITTING_END] = true
+      this.emit('end')
+      this.emit('prefinish')
+      this.emit('finish')
+      if (this[CLOSED])
+        this.emit('close')
+      this[EMITTING_END] = false
+    }
+  }
+
+  emit (ev, data, ...extra) {
+    // error and close are only events allowed after calling destroy()
+    if (ev !== 'error' && ev !== 'close' && ev !== DESTROYED && this[DESTROYED])
+      return
+    else if (ev === 'data') {
+      return !data ? false
+        : this[ASYNC] ? defer(() => this[EMITDATA](data))
+        : this[EMITDATA](data)
+    } else if (ev === 'end') {
+      return this[EMITEND]()
+    } else if (ev === 'close') {
+      this[CLOSED] = true
+      // don't emit close before 'end' and 'finish'
+      if (!this[EMITTED_END] && !this[DESTROYED])
+        return
+      const ret = super.emit('close')
+      this.removeAllListeners('close')
+      return ret
+    } else if (ev === 'error') {
+      this[EMITTED_ERROR] = data
+      const ret = super.emit('error', data)
+      this[MAYBE_EMIT_END]()
+      return ret
+    } else if (ev === 'resume') {
+      const ret = super.emit('resume')
+      this[MAYBE_EMIT_END]()
+      return ret
+    } else if (ev === 'finish' || ev === 'prefinish') {
+      const ret = super.emit(ev)
+      this.removeAllListeners(ev)
+      return ret
+    }
+
+    // Some other unknown event
+    const ret = super.emit(ev, data, ...extra)
+    this[MAYBE_EMIT_END]()
+    return ret
+  }
+
+  [EMITDATA] (data) {
+    for (const p of this.pipes) {
+      if (p.dest.write(data) === false)
+        this.pause()
+    }
+    const ret = super.emit('data', data)
+    this[MAYBE_EMIT_END]()
+    return ret
+  }
+
+  [EMITEND] () {
+    if (this[EMITTED_END])
+      return
+
+    this[EMITTED_END] = true
+    this.readable = false
+    if (this[ASYNC])
+      defer(() => this[EMITEND2]())
+    else
+      this[EMITEND2]()
+  }
+
+  [EMITEND2] () {
+    if (this[DECODER]) {
+      const data = this[DECODER].end()
+      if (data) {
+        for (const p of this.pipes) {
+          p.dest.write(data)
+        }
+        super.emit('data', data)
+      }
+    }
+
+    for (const p of this.pipes) {
+      p.end()
+    }
+    const ret = super.emit('end')
+    this.removeAllListeners('end')
+    return ret
+  }
+
+  // const all = await stream.collect()
+  collect () {
+    const buf = []
+    if (!this[OBJECTMODE])
+      buf.dataLength = 0
+    // set the promise first, in case an error is raised
+    // by triggering the flow here.
+    const p = this.promise()
+    this.on('data', c => {
+      buf.push(c)
+      if (!this[OBJECTMODE])
+        buf.dataLength += c.length
+    })
+    return p.then(() => buf)
+  }
+
+  // const data = await stream.concat()
+  concat () {
+    return this[OBJECTMODE]
+      ? Promise.reject(new Error('cannot concat in objectMode'))
+      : this.collect().then(buf =>
+          this[OBJECTMODE]
+            ? Promise.reject(new Error('cannot concat in objectMode'))
+            : this[ENCODING] ? buf.join('') : Buffer.concat(buf, buf.dataLength))
+  }
+
+  // stream.promise().then(() => done, er => emitted error)
+  promise () {
+    return new Promise((resolve, reject) => {
+      this.on(DESTROYED, () => reject(new Error('stream destroyed')))
+      this.on('error', er => reject(er))
+      this.on('end', () => resolve())
+    })
+  }
+
+  // for await (let chunk of stream)
+  [ASYNCITERATOR] () {
+    const next = () => {
+      const res = this.read()
+      if (res !== null)
+        return Promise.resolve({ done: false, value: res })
+
+      if (this[EOF])
+        return Promise.resolve({ done: true })
+
+      let resolve = null
+      let reject = null
+      const onerr = er => {
+        this.removeListener('data', ondata)
+        this.removeListener('end', onend)
+        reject(er)
+      }
+      const ondata = value => {
+        this.removeListener('error', onerr)
+        this.removeListener('end', onend)
+        this.pause()
+        resolve({ value: value, done: !!this[EOF] })
+      }
+      const onend = () => {
+        this.removeListener('error', onerr)
+        this.removeListener('data', ondata)
+        resolve({ done: true })
+      }
+      const ondestroy = () => onerr(new Error('stream destroyed'))
+      return new Promise((res, rej) => {
+        reject = rej
+        resolve = res
+        this.once(DESTROYED, ondestroy)
+        this.once('error', onerr)
+        this.once('end', onend)
+        this.once('data', ondata)
+      })
+    }
+
+    return { next }
+  }
+
+  // for (let chunk of stream)
+  [ITERATOR] () {
+    const next = () => {
+      const value = this.read()
+      const done = value === null
+      return { value, done }
+    }
+    return { next }
+  }
+
+  destroy (er) {
+    if (this[DESTROYED]) {
+      if (er)
+        this.emit('error', er)
+      else
+        this.emit(DESTROYED)
+      return this
+    }
+
+    this[DESTROYED] = true
+
+    // throw away all buffered data, it's never coming out
+    this.buffer.length = 0
+    this[BUFFERLENGTH] = 0
+
+    if (typeof this.close === 'function' && !this[CLOSED])
+      this.close()
+
+    if (er)
+      this.emit('error', er)
+    else // if no error to emit, still reject pending promises
+      this.emit(DESTROYED)
+
+    return this
+  }
+
+  static isStream (s) {
+    return !!s && (s instanceof Minipass || s instanceof Stream ||
+      s instanceof EE && (
+        typeof s.pipe === 'function' || // readable
+        (typeof s.write === 'function' && typeof s.end === 'function') // writable
+      ))
+  }
+}

unified-ai-platform/node_modules/ssri/node_modules/minipass/package.json

@@ -0,0 +1,56 @@
+{
+  "name": "minipass",
+  "version": "3.3.6",
+  "description": "minimal implementation of a PassThrough stream",
+  "main": "index.js",
+  "types": "index.d.ts",
+  "dependencies": {
+    "yallist": "^4.0.0"
+  },
+  "devDependencies": {
+    "@types/node": "^17.0.41",
+    "end-of-stream": "^1.4.0",
+    "prettier": "^2.6.2",
+    "tap": "^16.2.0",
+    "through2": "^2.0.3",
+    "ts-node": "^10.8.1",
+    "typescript": "^4.7.3"
+  },
+  "scripts": {
+    "test": "tap",
+    "preversion": "npm test",
+    "postversion": "npm publish",
+    "postpublish": "git push origin --follow-tags"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/isaacs/minipass.git"
+  },
+  "keywords": [
+    "passthrough",
+    "stream"
+  ],
+  "author": "Isaac Z. Schlueter <i@izs.me> (http://blog.izs.me/)",
+  "license": "ISC",
+  "files": [
+    "index.d.ts",
+    "index.js"
+  ],
+  "tap": {
+    "check-coverage": true
+  },
+  "engines": {
+    "node": ">=8"
+  },
+  "prettier": {
+    "semi": false,
+    "printWidth": 80,
+    "tabWidth": 2,
+    "useTabs": false,
+    "singleQuote": true,
+    "jsxSingleQuote": false,
+    "bracketSameLine": true,
+    "arrowParens": "avoid",
+    "endOfLine": "lf"
+  }
+}

unified-ai-platform/node_modules/ssri/node_modules/yallist/LICENSE

@@ -0,0 +1,15 @@
+The ISC License
+
+Copyright (c) Isaac Z. Schlueter and Contributors
+
+Permission to use, copy, modify, and/or distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
+IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

unified-ai-platform/node_modules/ssri/node_modules/yallist/iterator.js

@@ -0,0 +1,8 @@
+'use strict'
+module.exports = function (Yallist) {
+  Yallist.prototype[Symbol.iterator] = function* () {
+    for (let walker = this.head; walker; walker = walker.next) {
+      yield walker.value
+    }
+  }
+}

unified-ai-platform/node_modules/ssri/node_modules/yallist/package.json

@@ -0,0 +1,29 @@
+{
+  "name": "yallist",
+  "version": "4.0.0",
+  "description": "Yet Another Linked List",
+  "main": "yallist.js",
+  "directories": {
+    "test": "test"
+  },
+  "files": [
+    "yallist.js",
+    "iterator.js"
+  ],
+  "dependencies": {},
+  "devDependencies": {
+    "tap": "^12.1.0"
+  },
+  "scripts": {
+    "test": "tap test/*.js --100",
+    "preversion": "npm test",
+    "postversion": "npm publish",
+    "postpublish": "git push origin --all; git push origin --tags"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/isaacs/yallist.git"
+  },
+  "author": "Isaac Z. Schlueter <i@izs.me> (http://blog.izs.me/)",
+  "license": "ISC"
+}

unified-ai-platform/node_modules/ssri/node_modules/yallist/yallist.js

@@ -0,0 +1,426 @@
+'use strict'
+module.exports = Yallist
+
+Yallist.Node = Node
+Yallist.create = Yallist
+
+function Yallist (list) {
+  var self = this
+  if (!(self instanceof Yallist)) {
+    self = new Yallist()
+  }
+
+  self.tail = null
+  self.head = null
+  self.length = 0
+
+  if (list && typeof list.forEach === 'function') {
+    list.forEach(function (item) {
+      self.push(item)
+    })
+  } else if (arguments.length > 0) {
+    for (var i = 0, l = arguments.length; i < l; i++) {
+      self.push(arguments[i])
+    }
+  }
+
+  return self
+}
+
+Yallist.prototype.removeNode = function (node) {
+  if (node.list !== this) {
+    throw new Error('removing node which does not belong to this list')
+  }
+
+  var next = node.next
+  var prev = node.prev
+
+  if (next) {
+    next.prev = prev
+  }
+
+  if (prev) {
+    prev.next = next
+  }
+
+  if (node === this.head) {
+    this.head = next
+  }
+  if (node === this.tail) {
+    this.tail = prev
+  }
+
+  node.list.length--
+  node.next = null
+  node.prev = null
+  node.list = null
+
+  return next
+}
+
+Yallist.prototype.unshiftNode = function (node) {
+  if (node === this.head) {
+    return
+  }
+
+  if (node.list) {
+    node.list.removeNode(node)
+  }
+
+  var head = this.head
+  node.list = this
+  node.next = head
+  if (head) {
+    head.prev = node
+  }
+
+  this.head = node
+  if (!this.tail) {
+    this.tail = node
+  }
+  this.length++
+}
+
+Yallist.prototype.pushNode = function (node) {
+  if (node === this.tail) {
+    return
+  }
+
+  if (node.list) {
+    node.list.removeNode(node)
+  }
+
+  var tail = this.tail
+  node.list = this
+  node.prev = tail
+  if (tail) {
+    tail.next = node
+  }
+
+  this.tail = node
+  if (!this.head) {
+    this.head = node
+  }
+  this.length++
+}
+
+Yallist.prototype.push = function () {
+  for (var i = 0, l = arguments.length; i < l; i++) {
+    push(this, arguments[i])
+  }
+  return this.length
+}
+
+Yallist.prototype.unshift = function () {
+  for (var i = 0, l = arguments.length; i < l; i++) {
+    unshift(this, arguments[i])
+  }
+  return this.length
+}
+
+Yallist.prototype.pop = function () {
+  if (!this.tail) {
+    return undefined
+  }
+
+  var res = this.tail.value
+  this.tail = this.tail.prev
+  if (this.tail) {
+    this.tail.next = null
+  } else {
+    this.head = null
+  }
+  this.length--
+  return res
+}
+
+Yallist.prototype.shift = function () {
+  if (!this.head) {
+    return undefined
+  }
+
+  var res = this.head.value
+  this.head = this.head.next
+  if (this.head) {
+    this.head.prev = null
+  } else {
+    this.tail = null
+  }
+  this.length--
+  return res
+}
+
+Yallist.prototype.forEach = function (fn, thisp) {
+  thisp = thisp || this
+  for (var walker = this.head, i = 0; walker !== null; i++) {
+    fn.call(thisp, walker.value, i, this)
+    walker = walker.next
+  }
+}
+
+Yallist.prototype.forEachReverse = function (fn, thisp) {
+  thisp = thisp || this
+  for (var walker = this.tail, i = this.length - 1; walker !== null; i--) {
+    fn.call(thisp, walker.value, i, this)
+    walker = walker.prev
+  }
+}
+
+Yallist.prototype.get = function (n) {
+  for (var i = 0, walker = this.head; walker !== null && i < n; i++) {
+    // abort out of the list early if we hit a cycle
+    walker = walker.next
+  }
+  if (i === n && walker !== null) {
+    return walker.value
+  }
+}
+
+Yallist.prototype.getReverse = function (n) {
+  for (var i = 0, walker = this.tail; walker !== null && i < n; i++) {
+    // abort out of the list early if we hit a cycle
+    walker = walker.prev
+  }
+  if (i === n && walker !== null) {
+    return walker.value
+  }
+}
+
+Yallist.prototype.map = function (fn, thisp) {
+  thisp = thisp || this
+  var res = new Yallist()
+  for (var walker = this.head; walker !== null;) {
+    res.push(fn.call(thisp, walker.value, this))
+    walker = walker.next
+  }
+  return res
+}
+
+Yallist.prototype.mapReverse = function (fn, thisp) {
+  thisp = thisp || this
+  var res = new Yallist()
+  for (var walker = this.tail; walker !== null;) {
+    res.push(fn.call(thisp, walker.value, this))
+    walker = walker.prev
+  }
+  return res
+}
+
+Yallist.prototype.reduce = function (fn, initial) {
+  var acc
+  var walker = this.head
+  if (arguments.length > 1) {
+    acc = initial
+  } else if (this.head) {
+    walker = this.head.next
+    acc = this.head.value
+  } else {
+    throw new TypeError('Reduce of empty list with no initial value')
+  }
+
+  for (var i = 0; walker !== null; i++) {
+    acc = fn(acc, walker.value, i)
+    walker = walker.next
+  }
+
+  return acc
+}
+
+Yallist.prototype.reduceReverse = function (fn, initial) {
+  var acc
+  var walker = this.tail
+  if (arguments.length > 1) {
+    acc = initial
+  } else if (this.tail) {
+    walker = this.tail.prev
+    acc = this.tail.value
+  } else {
+    throw new TypeError('Reduce of empty list with no initial value')
+  }
+
+  for (var i = this.length - 1; walker !== null; i--) {
+    acc = fn(acc, walker.value, i)
+    walker = walker.prev
+  }
+
+  return acc
+}
+
+Yallist.prototype.toArray = function () {
+  var arr = new Array(this.length)
+  for (var i = 0, walker = this.head; walker !== null; i++) {
+    arr[i] = walker.value
+    walker = walker.next
+  }
+  return arr
+}
+
+Yallist.prototype.toArrayReverse = function () {
+  var arr = new Array(this.length)
+  for (var i = 0, walker = this.tail; walker !== null; i++) {
+    arr[i] = walker.value
+    walker = walker.prev
+  }
+  return arr
+}
+
+Yallist.prototype.slice = function (from, to) {
+  to = to || this.length
+  if (to < 0) {
+    to += this.length
+  }
+  from = from || 0
+  if (from < 0) {
+    from += this.length
+  }
+  var ret = new Yallist()
+  if (to < from || to < 0) {
+    return ret
+  }
+  if (from < 0) {
+    from = 0
+  }
+  if (to > this.length) {
+    to = this.length
+  }
+  for (var i = 0, walker = this.head; walker !== null && i < from; i++) {
+    walker = walker.next
+  }
+  for (; walker !== null && i < to; i++, walker = walker.next) {
+    ret.push(walker.value)
+  }
+  return ret
+}
+
+Yallist.prototype.sliceReverse = function (from, to) {
+  to = to || this.length
+  if (to < 0) {
+    to += this.length
+  }
+  from = from || 0
+  if (from < 0) {
+    from += this.length
+  }
+  var ret = new Yallist()
+  if (to < from || to < 0) {
+    return ret
+  }
+  if (from < 0) {
+    from = 0
+  }
+  if (to > this.length) {
+    to = this.length
+  }
+  for (var i = this.length, walker = this.tail; walker !== null && i > to; i--) {
+    walker = walker.prev
+  }
+  for (; walker !== null && i > from; i--, walker = walker.prev) {
+    ret.push(walker.value)
+  }
+  return ret
+}
+
+Yallist.prototype.splice = function (start, deleteCount, ...nodes) {
+  if (start > this.length) {
+    start = this.length - 1
+  }
+  if (start < 0) {
+    start = this.length + start;
+  }
+
+  for (var i = 0, walker = this.head; walker !== null && i < start; i++) {
+    walker = walker.next
+  }
+
+  var ret = []
+  for (var i = 0; walker && i < deleteCount; i++) {
+    ret.push(walker.value)
+    walker = this.removeNode(walker)
+  }
+  if (walker === null) {
+    walker = this.tail
+  }
+
+  if (walker !== this.head && walker !== this.tail) {
+    walker = walker.prev
+  }
+
+  for (var i = 0; i < nodes.length; i++) {
+    walker = insert(this, walker, nodes[i])
+  }
+  return ret;
+}
+
+Yallist.prototype.reverse = function () {
+  var head = this.head
+  var tail = this.tail
+  for (var walker = head; walker !== null; walker = walker.prev) {
+    var p = walker.prev
+    walker.prev = walker.next
+    walker.next = p
+  }
+  this.head = tail
+  this.tail = head
+  return this
+}
+
+function insert (self, node, value) {
+  var inserted = node === self.head ?
+    new Node(value, null, node, self) :
+    new Node(value, node, node.next, self)
+
+  if (inserted.next === null) {
+    self.tail = inserted
+  }
+  if (inserted.prev === null) {
+    self.head = inserted
+  }
+
+  self.length++
+
+  return inserted
+}
+
+function push (self, item) {
+  self.tail = new Node(item, self.tail, null, self)
+  if (!self.head) {
+    self.head = self.tail
+  }
+  self.length++
+}
+
+function unshift (self, item) {
+  self.head = new Node(item, null, self.head, self)
+  if (!self.tail) {
+    self.tail = self.head
+  }
+  self.length++
+}
+
+function Node (value, prev, next, list) {
+  if (!(this instanceof Node)) {
+    return new Node(value, prev, next, list)
+  }
+
+  this.list = list
+  this.value = value
+
+  if (prev) {
+    prev.next = this
+    this.prev = prev
+  } else {
+    this.prev = null
+  }
+
+  if (next) {
+    next.prev = this
+    this.next = next
+  } else {
+    this.next = null
+  }
+}
+
+try {
+  // add if support for Symbol.iterator is present
+  require('./iterator.js')(Yallist)
+} catch (er) {}