git ssb

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'use strict'
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function id (item) { return item }
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function prop (key) {
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  return (
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    'string' == typeof key
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    ? function (data) { return data[key] }
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    : key && 'object' === typeof key && 'function' === typeof key.exec //regexp
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    ? function (data) { var v = map.exec(data); return v && v[0] }
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    : key || id
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  )
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}
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var drain = exports.drain = function (op, done) {
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  var read, abort
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  function sink (_read) {
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    read = _read
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    if(abort) return sink.abort()
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    //this function is much simpler to write if you
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    //just use recursion, but by using a while loop
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    //we do not blow the stack if the stream happens to be sync.
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    ;(function next() {
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        var loop = true, cbed = false
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        while(loop) {
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          cbed = false
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          read(null, function (end, data) {
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            cbed = true
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            if(end = end || abort) {
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              loop = false
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              if(done) done(end === true ? null : end)
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              else if(end && end !== true)
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                throw end
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            }
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            else if(op && false === op(data) || abort) {
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              loop = false
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              read(abort || true, done || function () {})
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            }
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            else if(!loop){
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              next()
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            }
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          })
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          if(!cbed) {
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            loop = false
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            return
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          }
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        }
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      })()
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  }
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  sink.abort = function (err, cb) {
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    if('function' == typeof err)
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      cb = err, err = true
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    abort = err || true
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    if(read) return read(abort, cb || function () {})
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  }
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  return sink
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}
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var onEnd = exports.onEnd = function (done) {
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  return drain(null, done)
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}
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var log = exports.log = function (done) {
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  return drain(function (data) {
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    console.log(data)
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  }, done)
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}
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var find =
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exports.find = function (test, cb) {
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  var ended = false
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  if(!cb)
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    cb = test, test = id
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  else
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    test = prop(test) || id
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  return drain(function (data) {
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    if(test(data)) {
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      ended = true
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      cb(null, data)
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    return false
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    }
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  }, function (err) {
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    if(ended) return //already called back
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    cb(err === true ? null : err, null)
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  })
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}
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var reduce = exports.reduce = function (reduce, acc, cb) {
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  return drain(function (data) {
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    acc = reduce(acc, data)
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  }, function (err) {
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    cb(err, acc)
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  })
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}
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var collect = exports.collect =
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function (cb) {
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  return reduce(function (arr, item) {
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    arr.push(item)
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    return arr
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  }, [], cb)
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}
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var concat = exports.concat =
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function (cb) {
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  return reduce(function (a, b) {
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    return a + b
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  }, '', cb)
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}
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