General purpose task for building external modules

package.json

@@ -30,6 +30,7 @@
     "htmlparser2": "3.7.3",
     "jsdoc": "3.3.0-alpha9",
     "nomnom": "1.8.0",
+    "rbush": "1.3.4",
     "temp": "0.8.1",
     "walk": "2.3.4"
   },
@@ -43,5 +44,8 @@
     "phantomjs": "1.9.10",
     "proj4": "2.3.3",
     "sinon": "1.10.3"
-  }
+  },
+  "ext": [
+    "rbush"
+  ]
 }

tasks/build-ext.js

@@ -0,0 +1,84 @@
+var fs = require('fs');
+var path = require('path');
+
+var async = require('async');
+var fse = require('fs-extra');
+
+var pkg = require('../package.json');
+
+var root = path.join(__dirname, '..');
+var buildDir = path.join(root, 'build', 'ol.ext');
+
+
+/**
+ * Get external module metadata.
+ * @return {Array.<Object>} Array of objects representing external modules.
+ */
+function getExternalModules() {
+  return pkg.ext.map(function(name) {
+    return {
+      name: name,
+      main: require.resolve(name)
+    };
+  });
+}
+
+
+/**
+ * Wrap a CommonJS module in Closure Library accessible code.
+ * @param {Object} mod Module metadata.
+ * @param {function(Error, string)} callback Called with any error and the
+ *     wrapped module.
+ */
+function wrapModule(mod, callback) {
+  fs.readFile(mod.main, function(err, data) {
+    if (err) {
+      callback(err);
+      return;
+    }
+    var wrapped = 'goog.provide(\'ol.ext.' + mod.name + '\');\n' +
+        '(function() {\n' +
+        'var module = {};\n' +
+        '/**\n' +
+        ' * @fileoverview\n' +
+        ' * @suppress {accessControls, ambiguousFunctionDecl, ' +
+        'checkDebuggerStatement, checkRegExp, checkTypes, checkVars, const, ' +
+        'constantProperty, deprecated, duplicate, es5Strict, ' +
+        'fileoverviewTags, missingProperties, nonStandardJsDocs, ' +
+        'strictModuleDepCheck, suspiciousCode, undefinedNames, ' +
+        'undefinedVars, unknownDefines, uselessCode, visibility}\n' +
+        ' */\n' + data.toString() + '\n' +
+        'ol.ext.' + mod.name + ' = module.exports;\n' +
+        '})();\n';
+    callback(null, wrapped);
+  });
+}
+
+
+/**
+ * Build external modules.
+ * @param {Array.<Object>} modules External modules.
+ * @param {function(Error)} callback Called with any error.
+ */
+function buildModules(modules, callback) {
+  async.each(modules, function(mod, done) {
+    var output = path.join(buildDir, mod.name) + '.js';
+    async.waterfall([
+      wrapModule.bind(null, mod),
+      fse.outputFile.bind(fse, output)
+    ], done);
+  }, callback);
+}
+
+
+if (require.main === module) {
+  var modules = getExternalModules();
+  buildModules(modules, function(err) {
+    if (err) {
+      process.stderr.write(err.message + '\n');
+      process.exit(1);
+    } else {
+      process.exit(0);
+    }
+  });
+}