text: // Copyright 2014 Simon Lydell
  // X11 (“MIT”) Licensed. (See LICENSE.)
  
  var sourceMappingURL = require("source-map-url")
  var resolveUrl       = require("./resolve-url")
  var urix             = require("urix")
  var atob             = require("atob")
  
  
  
  function callbackAsync(callback, error, result) {
    setImmediate(function() { callback(error, result) })
  }
  
  function parseMapToJSON(string) {
    return JSON.parse(string.replace(/^\)\]\}'/, ""))
  }
  
  
  
  function resolveSourceMap(code, codeUrl, read, callback) {
    var mapData
    try {
      mapData = resolveSourceMapHelper(code, codeUrl)
    } catch (error) {
      return callbackAsync(callback, error)
    }
    if (!mapData || mapData.map) {
      return callbackAsync(callback, null, mapData)
    }
    read(mapData.url, function(error, result) {
      if (error) {
        return callback(error)
      }
      try {
        mapData.map = parseMapToJSON(String(result))
      } catch (error) {
        return callback(error)
      }
      callback(null, mapData)
    })
  }
  
  function resolveSourceMapSync(code, codeUrl, read) {
    var mapData = resolveSourceMapHelper(code, codeUrl)
    if (!mapData || mapData.map) {
      return mapData
    }
    mapData.map = parseMapToJSON(String(read(mapData.url)))
    return mapData
  }
  
  var dataUriRegex = /^data:([^,;]*)(;[^,;]*)*(?:,(.*))?$/
  var jsonMimeTypeRegex = /^(?:application|text)\/json$/
  
  function resolveSourceMapHelper(code, codeUrl) {
    codeUrl = urix(codeUrl)
  
    var url = sourceMappingURL.getFrom(code)
    if (!url) {
      return null
    }
  
    var dataUri = url.match(dataUriRegex)
    if (dataUri) {
      var mimeType = dataUri[1]
      var lastParameter = dataUri[2]
      var encoded = dataUri[3]
      if (!jsonMimeTypeRegex.test(mimeType)) {
        throw new Error("Unuseful data uri mime type: " + (mimeType || "text/plain"))
      }
      return {
        sourceMappingURL: url,
        url: null,
        sourcesRelativeTo: codeUrl,
        map: parseMapToJSON(lastParameter === ";base64" ? atob(encoded) : decodeURIComponent(encoded))
      }
    }
  
    var mapUrl = resolveUrl(codeUrl, url)
    return {
      sourceMappingURL: url,
      url: mapUrl,
      sourcesRelativeTo: mapUrl,
      map: null
    }
  }
  
  
  
  function resolveSources(map, mapUrl, read, options, callback) {
    if (typeof options === "function") {
      callback = options
      options = {}
    }
    var pending = map.sources.length
    var errored = false
    var result = {
      sourcesResolved: [],
      sourcesContent:  []
    }
  
    var done = function(error) {
      if (errored) {
        return
      }
      if (error) {
        errored = true
        return callback(error)
      }
      pending--
      if (pending === 0) {
        callback(null, result)
      }
    }
  
    resolveSourcesHelper(map, mapUrl, options, function(fullUrl, sourceContent, index) {
      result.sourcesResolved[index] = fullUrl
      if (typeof sourceContent === "string") {
        result.sourcesContent[index] = sourceContent
        callbackAsync(done, null)
      } else {
        read(fullUrl, function(error, source) {
          result.sourcesContent[index] = String(source)
          done(error)
        })
      }
    })
  }
  
  function resolveSourcesSync(map, mapUrl, read, options) {
    var result = {
      sourcesResolved: [],
      sourcesContent:  []
    }
    resolveSourcesHelper(map, mapUrl, options, function(fullUrl, sourceContent, index) {
      result.sourcesResolved[index] = fullUrl
      if (read !== null) {
        if (typeof sourceContent === "string") {
          result.sourcesContent[index] = sourceContent
        } else {
          result.sourcesContent[index] = String(read(fullUrl))
        }
      }
    })
    return result
  }
  
  var endingSlash = /\/?$/
  
  function resolveSourcesHelper(map, mapUrl, options, fn) {
    options = options || {}
    mapUrl = urix(mapUrl)
    var fullUrl
    var sourceContent
    for (var index = 0, len = map.sources.length; index < len; index++) {
      if (map.sourceRoot && !options.ignoreSourceRoot) {
        // Make sure that the sourceRoot ends with a slash, so that `/scripts/subdir` becomes
        // `/scripts/subdir/<source>`, not `/scripts/<source>`. Pointing to a file as source root
        // does not make sense.
        fullUrl = resolveUrl(mapUrl, map.sourceRoot.replace(endingSlash, "/"), map.sources[index])
      } else {
        fullUrl = resolveUrl(mapUrl, map.sources[index])
      }
      sourceContent = (map.sourcesContent || [])[index]
      fn(fullUrl, sourceContent, index)
    }
  }
  
  
  
  function resolve(code, codeUrl, read, options, callback) {
    if (typeof options === "function") {
      callback = options
      options = {}
    }
    resolveSourceMap(code, codeUrl, read, function(error, mapData) {
      if (error) {
        return callback(error)
      }
      if (!mapData) {
        return callback(null, null)
      }
      resolveSources(mapData.map, mapData.sourcesRelativeTo, read, options, function(error, result) {
        if (error) {
          return callback(error)
        }
        mapData.sourcesResolved = result.sourcesResolved
        mapData.sourcesContent  = result.sourcesContent
        callback(null, mapData)
      })
    })
  }
  
  function resolveSync(code, codeUrl, read, options) {
    var mapData = resolveSourceMapSync(code, codeUrl, read)
    if (!mapData) {
      return null
    }
    var result = resolveSourcesSync(mapData.map, mapData.sourcesRelativeTo, read, options)
    mapData.sourcesResolved = result.sourcesResolved
    mapData.sourcesContent  = result.sourcesContent
    return mapData
  }
  
  
  
  module.exports = {
    resolveSourceMap:     resolveSourceMap,
    resolveSourceMapSync: resolveSourceMapSync,
    resolveSources:       resolveSources,
    resolveSourcesSync:   resolveSourcesSync,
    resolve:              resolve,
    resolveSync:          resolveSync
  }
  