Ushio-cn-old/yimian/iot/mqtt/smartfarm/node_modules/levelup/lib/leveldown.js

var LevelUPError = require('level-errors').LevelUPError
var format = require('util').format
var leveldown

function getLevelDOWN () {
  if (leveldown) { return leveldown }

  var requiredVersion = require('../package.json').devDependencies.leveldown
  var leveldownVersion

  try {
    leveldownVersion = require('leveldown/package.json').version
  } catch (e) {
    throw requireError(e)
  }

  if (!require('semver').satisfies(leveldownVersion, requiredVersion)) {
    throw new LevelUPError(
        'Installed version of LevelDOWN (' +
      leveldownVersion +
      ') does not match required version (' +
      requiredVersion +
      ')'
    )
  }

  try {
    leveldown = require('leveldown')
    return leveldown
  } catch (e) {
    throw requireError(e)
  }
}

function requireError (e) {
  var template = 'Failed to require LevelDOWN (%s). Try `npm install leveldown` if it\'s missing'
  return new LevelUPError(format(template, e.message))
}

module.exports = getLevelDOWN