git ssb

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const cbor = require('borc')
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const EMPTY_STATE_ROOT = Buffer.from('4cf812be9be2c6008325050f43d06676a08612c7', 'hex')
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const LINK_TAG = 42
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function insertTags (val) {
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  if (Array.isArray(val)) {
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    val = val.map(v => {
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      if (v && v.hasOwnProperty('/')) {
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        return new cbor.Tagged(LINK_TAG, v['/'])
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      } else {
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        return insertTags(v)
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      }
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    })
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  }
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  return val
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}
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// helper functions for nodes
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const EXTENSION = exports.EXTENSION = 0
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const LBRANCH = exports.LBRANCH = 1
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const RBRANCH = exports.RBRANCH = 2
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const VALUE = exports.VALUE = 3
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exports.setBranch = function (node, branch) {
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  node['/'][LBRANCH] = branch[0]
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  node['/'][RBRANCH] = branch[1]
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}
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exports.getBranch = function (node) {
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  return node['/'].slice(LBRANCH, LBRANCH + 2)
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}
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exports.getValue = function (node) {
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  return node['/'][VALUE]
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}
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exports.deleteValue = function (node) {
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  node['/'] = node['/'].slice(0, 3)
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}
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exports.getExtension = function (node) {
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  if (node['/'][EXTENSION]) {
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    const len = node['/'][EXTENSION][0]
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    const extension = exports.buffer2bits(node['/'][EXTENSION][1])
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    return extension.slice(0, len)
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  } else {
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    return []
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  }
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}
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exports.setExtension = function (node, ex) {
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  if (ex && ex.length) {
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    node['/'][EXTENSION] = [ex.length, exports.bit2buffer(ex)]
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  } else {
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    node['/'][EXTENSION] = null
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  }
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}
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exports.setValue = function (node, val) {
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  if (val !== undefined) {
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    node['/'][VALUE] = val
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  }
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}
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exports.isEmpty = function (node) {
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  if (Buffer.isBuffer(node['/'])) {
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    return !Buffer.compare(node['/'], EMPTY_STATE_ROOT)
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  } else {
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    return node['/'].every(el => !el)
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  }
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}
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exports.encodeNode = function (node) {
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  const val = insertTags(node)
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  const encoded = cbor.encode(val)
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  return encoded
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}
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exports.buffer2bits = function (buffer) {
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  const bitArray = []
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  for (const elem of buffer) {
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    for (let i = 7; i >= 0; i--) {
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      bitArray.push((elem & (1 << i)) >> i)
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    }
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  }
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  return bitArray
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}
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exports.bit2buffer = function (bits) {
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  bits = bits.slice(0)
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  const byteArray = []
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  for (const index in bits) {
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    const bit = bits[index]
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    const arrayIndex = Math.floor(index / 8)
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    byteArray[arrayIndex] = byteArray[arrayIndex] | bit << (7 - (index % 8))
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  }
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  return Buffer.from(byteArray)
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}
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