'use strict'
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const assert = require('assert')
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const Buffer = require('buffer').Buffer
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const realZlib = require('zlib')
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const constants = exports.constants = require('./constants.js')
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const Minipass = require('minipass')
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const OriginalBufferConcat = Buffer.concat
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const _superWrite = Symbol('_superWrite')
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class ZlibError extends Error {
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constructor (err) {
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super('zlib: ' + err.message)
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this.code = err.code
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this.errno = err.errno
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/* istanbul ignore if */
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if (!this.code)
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this.code = 'ZLIB_ERROR'
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this.message = 'zlib: ' + err.message
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Error.captureStackTrace(this, this.constructor)
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}
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get name () {
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return 'ZlibError'
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}
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}
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// the Zlib class they all inherit from
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// This thing manages the queue of requests, and returns
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// true or false if there is anything in the queue when
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// you call the .write() method.
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const _opts = Symbol('opts')
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const _flushFlag = Symbol('flushFlag')
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const _finishFlushFlag = Symbol('finishFlushFlag')
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const _fullFlushFlag = Symbol('fullFlushFlag')
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const _handle = Symbol('handle')
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const _onError = Symbol('onError')
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const _sawError = Symbol('sawError')
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const _level = Symbol('level')
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const _strategy = Symbol('strategy')
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const _ended = Symbol('ended')
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const _defaultFullFlush = Symbol('_defaultFullFlush')
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class ZlibBase extends Minipass {
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constructor (opts, mode) {
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if (!opts || typeof opts !== 'object')
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throw new TypeError('invalid options for ZlibBase constructor')
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super(opts)
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this[_sawError] = false
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this[_ended] = false
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this[_opts] = opts
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this[_flushFlag] = opts.flush
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this[_finishFlushFlag] = opts.finishFlush
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// this will throw if any options are invalid for the class selected
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try {
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this[_handle] = new realZlib[mode](opts)
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} catch (er) {
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// make sure that all errors get decorated properly
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throw new ZlibError(er)
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}
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this[_onError] = (err) => {
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// no sense raising multiple errors, since we abort on the first one.
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if (this[_sawError])
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return
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this[_sawError] = true
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// there is no way to cleanly recover.
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// continuing only obscures problems.
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this.close()
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this.emit('error', err)
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}
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this[_handle].on('error', er => this[_onError](new ZlibError(er)))
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this.once('end', () => this.close)
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}
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close () {
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if (this[_handle]) {
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this[_handle].close()
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this[_handle] = null
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this.emit('close')
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}
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}
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reset () {
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if (!this[_sawError]) {
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assert(this[_handle], 'zlib binding closed')
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return this[_handle].reset()
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}
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}
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flush (flushFlag) {
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if (this.ended)
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return
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if (typeof flushFlag !== 'number')
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flushFlag = this[_fullFlushFlag]
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this.write(Object.assign(Buffer.alloc(0), { [_flushFlag]: flushFlag }))
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}
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end (chunk, encoding, cb) {
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if (chunk)
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this.write(chunk, encoding)
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this.flush(this[_finishFlushFlag])
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this[_ended] = true
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return super.end(null, null, cb)
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}
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get ended () {
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return this[_ended]
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}
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write (chunk, encoding, cb) {
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// process the chunk using the sync process
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// then super.write() all the outputted chunks
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if (typeof encoding === 'function')
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cb = encoding, encoding = 'utf8'
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if (typeof chunk === 'string')
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chunk = Buffer.from(chunk, encoding)
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if (this[_sawError])
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return
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assert(this[_handle], 'zlib binding closed')
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// _processChunk tries to .close() the native handle after it's done, so we
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// intercept that by temporarily making it a no-op.
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const nativeHandle = this[_handle]._handle
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const originalNativeClose = nativeHandle.close
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nativeHandle.close = () => {}
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const originalClose = this[_handle].close
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this[_handle].close = () => {}
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// It also calls `Buffer.concat()` at the end, which may be convenient
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// for some, but which we are not interested in as it slows us down.
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Buffer.concat = (args) => args
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let result
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try {
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const flushFlag = typeof chunk[_flushFlag] === 'number'
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? chunk[_flushFlag] : this[_flushFlag]
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result = this[_handle]._processChunk(chunk, flushFlag)
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// if we don't throw, reset it back how it was
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Buffer.concat = OriginalBufferConcat
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} catch (err) {
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// or if we do, put Buffer.concat() back before we emit error
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// Error events call into user code, which may call Buffer.concat()
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Buffer.concat = OriginalBufferConcat
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this[_onError](new ZlibError(err))
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} finally {
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if (this[_handle]) {
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// Core zlib resets `_handle` to null after attempting to close the
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// native handle. Our no-op handler prevented actual closure, but we
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// need to restore the `._handle` property.
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this[_handle]._handle = nativeHandle
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nativeHandle.close = originalNativeClose
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this[_handle].close = originalClose
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// `_processChunk()` adds an 'error' listener. If we don't remove it
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// after each call, these handlers start piling up.
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this[_handle].removeAllListeners('error')
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// make sure OUR error listener is still attached tho
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}
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}
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if (this[_handle])
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this[_handle].on('error', er => this[_onError](new ZlibError(er)))
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let writeReturn
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if (result) {
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if (Array.isArray(result) && result.length > 0) {
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// The first buffer is always `handle._outBuffer`, which would be
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// re-used for later invocations; so, we always have to copy that one.
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writeReturn = this[_superWrite](Buffer.from(result[0]))
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for (let i = 1; i < result.length; i++) {
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writeReturn = this[_superWrite](result[i])
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}
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} else {
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writeReturn = this[_superWrite](Buffer.from(result))
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}
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}
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if (cb)
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cb()
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return writeReturn
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}
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[_superWrite] (data) {
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return super.write(data)
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}
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}
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class Zlib extends ZlibBase {
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constructor (opts, mode) {
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opts = opts || {}
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opts.flush = opts.flush || constants.Z_NO_FLUSH
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opts.finishFlush = opts.finishFlush || constants.Z_FINISH
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super(opts, mode)
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this[_fullFlushFlag] = constants.Z_FULL_FLUSH
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this[_level] = opts.level
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this[_strategy] = opts.strategy
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}
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params (level, strategy) {
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if (this[_sawError])
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return
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if (!this[_handle])
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throw new Error('cannot switch params when binding is closed')
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// no way to test this without also not supporting params at all
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/* istanbul ignore if */
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if (!this[_handle].params)
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throw new Error('not supported in this implementation')
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if (this[_level] !== level || this[_strategy] !== strategy) {
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this.flush(constants.Z_SYNC_FLUSH)
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assert(this[_handle], 'zlib binding closed')
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// .params() calls .flush(), but the latter is always async in the
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// core zlib. We override .flush() temporarily to intercept that and
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// flush synchronously.
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const origFlush = this[_handle].flush
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this[_handle].flush = (flushFlag, cb) => {
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this.flush(flushFlag)
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cb()
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}
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try {
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this[_handle].params(level, strategy)
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} finally {
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this[_handle].flush = origFlush
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}
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/* istanbul ignore else */
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if (this[_handle]) {
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this[_level] = level
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this[_strategy] = strategy
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}
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}
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}
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}
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// minimal 2-byte header
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class Deflate extends Zlib {
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constructor (opts) {
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super(opts, 'Deflate')
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}
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}
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class Inflate extends Zlib {
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constructor (opts) {
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super(opts, 'Inflate')
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}
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}
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// gzip - bigger header, same deflate compression
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const _portable = Symbol('_portable')
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class Gzip extends Zlib {
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constructor (opts) {
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super(opts, 'Gzip')
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this[_portable] = opts && !!opts.portable
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}
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[_superWrite] (data) {
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if (!this[_portable])
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return super[_superWrite](data)
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// we'll always get the header emitted in one first chunk
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// overwrite the OS indicator byte with 0xFF
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this[_portable] = false
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data[9] = 255
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return super[_superWrite](data)
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}
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}
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class Gunzip extends Zlib {
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constructor (opts) {
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super(opts, 'Gunzip')
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}
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}
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// raw - no header
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class DeflateRaw extends Zlib {
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constructor (opts) {
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super(opts, 'DeflateRaw')
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}
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}
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class InflateRaw extends Zlib {
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constructor (opts) {
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super(opts, 'InflateRaw')
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}
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}
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// auto-detect header.
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class Unzip extends Zlib {
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constructor (opts) {
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super(opts, 'Unzip')
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}
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}
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class Brotli extends ZlibBase {
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constructor (opts, mode) {
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opts = opts || {}
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opts.flush = opts.flush || constants.BROTLI_OPERATION_PROCESS
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opts.finishFlush = opts.finishFlush || constants.BROTLI_OPERATION_FINISH
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super(opts, mode)
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this[_fullFlushFlag] = constants.BROTLI_OPERATION_FLUSH
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}
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}
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class BrotliCompress extends Brotli {
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constructor (opts) {
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super(opts, 'BrotliCompress')
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}
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}
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class BrotliDecompress extends Brotli {
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constructor (opts) {
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super(opts, 'BrotliDecompress')
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}
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}
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exports.Deflate = Deflate
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exports.Inflate = Inflate
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exports.Gzip = Gzip
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exports.Gunzip = Gunzip
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exports.DeflateRaw = DeflateRaw
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exports.InflateRaw = InflateRaw
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exports.Unzip = Unzip
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/* istanbul ignore else */
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if (typeof realZlib.BrotliCompress === 'function') {
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exports.BrotliCompress = BrotliCompress
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exports.BrotliDecompress = BrotliDecompress
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} else {
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exports.BrotliCompress = exports.BrotliDecompress = class {
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constructor () {
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throw new Error('Brotli is not supported in this version of Node.js')
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}
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}
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}
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