git ssb

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var crypto = require('crypto')
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module.exports = function (type, encoding, onEnd) {
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  if (onEnd == null) onEnd = encoding, encoding = null
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  var hash = (typeof type == 'string') ? crypto.createHash(type) : type
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  var ended
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  function hasher(read) {
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    return function (abort, cb) {
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      read(abort, function (end, data) {
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        if (end === true && !hasher.digest) hasher.digest = hash.digest(encoding)
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        else if (!end) hash.update(data)
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        if (end && onEnd && !ended) {
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          onEnd(end === true ? null : end, hasher.digest)
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          ended = true
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        }
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        cb(end, data)
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      })
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    }
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  }
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  hasher.hash = hash
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  return hasher
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}
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