text: 
  module.exports = exports = configure
  
  /**
   * Module dependencies.
   */
  
  var fs = require('graceful-fs')
    , path = require('path')
    , glob = require('glob')
    , log = require('npmlog')
    , osenv = require('osenv')
    , which = require('which')
    , semver = require('semver')
    , mkdirp = require('mkdirp')
    , cp = require('child_process')
    , exec = cp.exec
    , spawn = cp.spawn
    , execFile = cp.execFile
    , win = process.platform == 'win32'
  
  exports.usage = 'Generates ' + (win ? 'MSVC project files' : 'a Makefile') + ' for the current module'
  
  function configure (gyp, argv, callback) {
  
    var python = gyp.opts.python || process.env.PYTHON || 'python'
      , buildDir = path.resolve('build')
      , hasVCExpress = false
      , hasWin71SDK = false
      , configPath
      , nodeDir
  
    if (win) {
      checkVCExpress(function () {
        if (hasVCExpress) {
          checkWin71SDK(function () {
            checkPython()
          })
        } else {
          checkPython()
        }
      })
    } else {
      checkPython()
    }
  
    // Check if Python is in the $PATH
    function checkPython () {
      log.verbose('check python', 'checking for Python executable "%s" in the PATH', python)
      which(python, function (err, execPath) {
        if (err) {
          log.verbose('`which` failed for `%s`', python, err)
          if (win) {
            guessPython()
          } else {
            failNoPython()
          }
        } else {
          log.verbose('`which` succeeded for `%s`', python, execPath)
          checkPythonVersion()
        }
      })
    }
  
    // Called on Windows when "python" isn't available in the current $PATH.
    // We're gonna check if "%SystemDrive%\python27\python.exe" exists.
    function guessPython () {
      log.verbose('could not find "' + python + '". guessing location')
      var rootDir = process.env.SystemDrive || 'C:\\'
      if (rootDir[rootDir.length - 1] !== '\\') {
        rootDir += '\\'
      }
      var pythonPath = path.resolve(rootDir, 'Python27', 'python.exe')
      log.verbose('ensuring that file exists:', pythonPath)
      fs.stat(pythonPath, function (err, stat) {
        if (err) {
          if (err.code == 'ENOENT') {
            failNoPython()
          } else {
            callback(err)
          }
          return
        }
        python = pythonPath
        checkPythonVersion()
      })
    }
  
    function checkPythonVersion () {
      execFile(python, ['-c', 'import platform; print platform.python_version();'], function (err, stdout) {
        if (err) {
          return callback(err)
        }
        log.verbose('check python version', '`%s -c "import platform; print platform.python_version();"` returned: %j', python, stdout)
        var version = stdout.trim()
        if (~version.indexOf('+')) {
          log.silly('stripping "+" sign(s) from version')
          version = version.replace(/\+/g, '')
        }
        if (semver.gte(version, '2.5.0') && semver.lt(version, '3.0.0')) {
          getNodeDir()
        } else {
          failPythonVersion(version)
        }
      })
    }
  
    function failNoPython () {
      callback(new Error('Can\'t find Python executable "' + python
            + '", you can set the PYTHON env variable.'))
    }
  
    function failPythonVersion (badVersion) {
      callback(new Error('Python executable "' + python
            + '" is v' + badVersion + ', which is not supported by gyp.\n'
            + 'You can pass the --python switch to point to Python >= v2.5.0 & < 3.0.0.'))
    }
  
    function checkWin71SDK(cb) {
      spawn('reg', ['query', 'HKLM\\Software\\Microsoft\\Microsoft SDKs\\Windows\\v7.1', '/v', 'InstallationFolder'])
           .on('exit', function (code) {
             hasWin71SDK = (code === 0)
             cb()
           })
    }
  
    function checkVCExpress64(cb) {
      var cp = spawn('cmd', ['/C', '%WINDIR%\\SysWOW64\\reg', 'query', 'HKLM\\Software\\Microsoft\\VCExpress\\10.0\\Setup\\VC', '/v', 'ProductDir'])
      cp.on('exit', function (code) {
        hasVCExpress = (code === 0)
        cb()
      })
    }
  
    function checkVCExpress(cb) {
      spawn('reg', ['query', 'HKLM\\Software\\Microsoft\\VCExpress\\10.0\\Setup\\VC', '/v', 'ProductDir'])
           .on('exit', function (code) {
             if (code !== 0) {
               checkVCExpress64(cb)
             } else {
               cb()
             }
           })
    }
  
    function getNodeDir () {
  
      // 'python' should be set by now
      process.env.PYTHON = python
  
      if (gyp.opts.nodedir) {
        // --nodedir was specified. use that for the dev files
        nodeDir = gyp.opts.nodedir.replace(/^~/, osenv.home())
  
        log.verbose('get node dir', 'compiling against specified --nodedir dev files: %s', nodeDir)
        createBuildDir()
  
      } else {
        // if no --nodedir specified, ensure node dependencies are installed
        var version
        var versionStr
  
        if (gyp.opts.target) {
          // if --target was given, then determine a target version to compile for
          versionStr = gyp.opts.target
          log.verbose('get node dir', 'compiling against --target node version: %s', versionStr)
        } else {
          // if no --target was specified then use the current host node version
          versionStr = process.version
          log.verbose('get node dir', 'no --target version specified, falling back to host node version: %s', versionStr)
        }
  
        // make sure we have a valid version
        version = semver.parse(versionStr)
        if (!version) {
          return callback(new Error('Invalid version number: ' + versionStr))
        }
  
        // ensure that the target node version's dev files are installed
        gyp.opts.ensure = true
        gyp.commands.install([ versionStr ], function (err, version) {
          if (err) return callback(err)
          log.verbose('get node dir', 'target node version installed:', version)
          nodeDir = path.resolve(gyp.devDir, version)
          createBuildDir()
        })
      }
    }
  
    function createBuildDir () {
      log.verbose('build dir', 'attempting to create "build" dir: %s', buildDir)
      mkdirp(buildDir, function (err, isNew) {
        if (err) return callback(err)
        log.verbose('build dir', '"build" dir needed to be created?', isNew)
        createConfigFile()
      })
    }
  
    function createConfigFile (err) {
      if (err) return callback(err)
  
      var configFilename = 'config.gypi'
      configPath = path.resolve(buildDir, configFilename)
  
      log.verbose(configFilename, 'creating config file')
  
      var config = process.config || {}
        , defaults = config.target_defaults
        , variables = config.variables
  
      if (!defaults) {
        defaults = config.target_defaults = {}
      }
      if (!variables) {
        variables = config.variables = {}
      }
      if (!defaults.cflags) {
        defaults.cflags = []
      }
      if (!defaults.defines) {
        defaults.defines = []
      }
      if (!defaults.include_dirs) {
        defaults.include_dirs = []
      }
      if (!defaults.libraries) {
        defaults.libraries = []
      }
  
      // set the default_configuration prop
      if ('debug' in gyp.opts) {
        defaults.default_configuration = gyp.opts.debug ? 'Debug' : 'Release'
      }
      if (!defaults.default_configuration) {
        defaults.default_configuration = 'Release'
      }
  
      // set the target_arch variable
      variables.target_arch = gyp.opts.arch || process.arch || 'ia32'
  
      // set the toolset for 64-bit VCExpress users
      if (win && variables.target_arch === 'x64' && hasVCExpress && hasWin71SDK) {
        defaults.msbuild_toolset = 'Windows7.1SDK'
      }
  
      // set the node development directory
      variables.nodedir = nodeDir
  
      // don't copy dev libraries with nodedir option
      variables.copy_dev_lib = !gyp.opts.nodedir
  
      // loop through the rest of the opts and add the unknown ones as variables.
      // this allows for module-specific configure flags like:
      //
      //   $ node-gyp configure --shared-libxml2
      Object.keys(gyp.opts).forEach(function (opt) {
        if (opt === 'argv') return
        if (opt in gyp.configDefs) return
        variables[opt.replace(/-/g, '_')] = gyp.opts[opt]
      })
  
      // ensures that any boolean values from `process.config` get stringified
      function boolsToString (k, v) {
        if (typeof v === 'boolean')
          return String(v)
        return v
      }
  
      log.silly(configFilename, config)
  
      // now write out the config.gypi file to the build/ dir
      var prefix = '# Do not edit. File was generated by node-gyp\'s "configure" step'
        , json = JSON.stringify(config, boolsToString, 2)
      log.verbose(configFilename, 'writing out config file: %s', configPath)
      fs.writeFile(configPath, [prefix, json, ''].join('\n'), runGyp)
    }
  
    function runGyp (err) {
      if (err) return callback(err)
  
      if (!~argv.indexOf('-f') && !~argv.indexOf('--format')) {
        if (win) {
          log.verbose('gyp', 'gyp format was not specified; forcing "msvs"')
          // force the 'make' target for non-Windows
          argv.push('-f', 'msvs')
        } else {
          log.verbose('gyp', 'gyp format was not specified; forcing "make"')
          // force the 'make' target for non-Windows
          argv.push('-f', 'make')
        }
      }
  
      function hasMsvsVersion () {
        return argv.some(function (arg) {
          return arg.indexOf('msvs_version') === 0
        })
      }
  
      if (win && !hasMsvsVersion()) {
        if ('msvs_version' in gyp.opts) {
          argv.push('-G', 'msvs_version=' + gyp.opts.msvs_version)
        } else {
          argv.push('-G', 'msvs_version=2010')
        }
      }
  
      // include the "config.gypi" file that was generated
      argv.push('-I', configPath)
  
      // this logic ported from the old `gyp_addon` python file
      var gyp_script = path.resolve(nodeDir, 'tools', 'gyp', 'gyp')
      var addon_gypi = path.resolve(__dirname, '..', 'addon.gypi')
      var common_gypi = path.resolve(nodeDir, 'common.gypi')
      var output_dir = 'build'
      if (win) {
        // Windows expects an absolute path
        output_dir = buildDir
      }
  
      argv.push('-I', addon_gypi)
      argv.push('-I', common_gypi)
      argv.push('-Dlibrary=shared_library')
      argv.push('-Dvisibility=default')
      argv.push('-Dnode_root_dir=' + nodeDir)
      argv.push('-Dmodule_root_dir=' + process.cwd())
      argv.push('--depth=.');
  
      // tell gyp to write the Makefile/Solution files into output_dir
      argv.push('--generator-output', output_dir)
  
      // tell make to write its output into the same dir
      argv.push('-Goutput_dir=.')
  
      // enforce use of the "binding.gyp" file
      argv.unshift('binding.gyp')
  
      // execute `gyp` from the current target nodedir
      argv.unshift(gyp_script)
  
      var cp = gyp.spawn(python, argv)
      cp.on('exit', onCpExit)
    }
  
    /**
     * Called when the `gyp` child process exits.
     */
  
    function onCpExit (code, signal) {
      if (code !== 0) {
        callback(new Error('`gyp` failed with exit code: ' + code))
      } else {
        // we're done
        callback()
      }
    }
  
  }
  