google/i18n/libphonenumber - node.js script to prepare single-country metadata files

slice_country.js

/*
	SCLEXE - single-country libphonenumber executable
	Author: Marco Faustinelli (contacts@faustinelli.net)
	Web: http://faustinelli.net/
	     http://faustinelli.wordpress.com/
	Version: 1.0
	The MIT License - Copyright (c) 2015 SCLEXE Project
*/

var fs = require('fs');
var vm = require('vm');
var util = require('util');

var companyIsoCode = process.argv[2];
var googleMetadataIsoCode = (companyIsoCode === 'UK') ? 'GB' : companyIsoCode;
var metadatafilename = process.argv[3];
var outputfilename = process.argv[4];
var context = {
  goog: {
    provide: function(){}
  },
  i18n: {
    phonenumbers: {
      metadata: {}
    }
  }
};

var metadata = fs.readFileSync(metadatafilename);

vm.runInNewContext(metadata, context);

var countryCode = 0;
for (var cc in context.i18n.phonenumbers.metadata.countryCodeToRegionCodeMap) {
  if (context.i18n.phonenumbers.metadata.countryCodeToRegionCodeMap[cc].indexOf(googleMetadataIsoCode) !== -1) {
    countryCode = cc;
    break;
  }
}

if (countryCode === 0) {
  console.error('cannot set countryCode');
  process.exit(1);
}

var countryToMetadata = {};
countryToMetadata[companyIsoCode] = context.i18n.phonenumbers.metadata.countryToMetadata[googleMetadataIsoCode];

var countryCodeToRegionCodeMap = {};
var cctrcmcc = context.i18n.phonenumbers.metadata.countryCodeToRegionCodeMap[countryCode];
cctrcmcc = cctrcmcc.map(function(ic) { return ic.replace(googleMetadataIsoCode, companyIsoCode); });
countryCodeToRegionCodeMap[countryCode] = cctrcmcc;

var output = util.format("\
  goog.provide('i18n.phonenumbers.metadata');\n\
  i18n.phonenumbers.metadata.countryCodeToRegionCodeMap = %j;\n\
  i18n.phonenumbers.metadata.countryToMetadata = %j;\
", countryCodeToRegionCodeMap, countryToMetadata);

fs.writeFileSync(outputfilename, output);

Starting from the whole metadata of the original libphonenumber project and an ISO code for a given country, this node.js script writes a file containing the sole metadata for that country.
Due to some ancient fawlty decision, I have to map isocode 'GB' into the value 'UK' used in the legacy code I am dealing with.
This script is invoked from ant project build.xml.

With many thanks to @gabrielelana for connecting lots of dots.