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node_modules/require_optional/index.js

@@ -0,0 +1,128 @@
+var path = require('path'),
+  fs = require('fs'),
+  f = require('util').format,
+  resolveFrom = require('resolve-from'),
+  semver = require('semver');
+
+var exists = fs.existsSync || path.existsSync;
+
+// Find the location of a package.json file near or above the given location
+var find_package_json = function(location) {
+  var found = false;
+
+  while(!found) {
+    if (exists(location + '/package.json')) {
+      found = location;
+    } else if (location !== '/') {
+      location = path.dirname(location);
+    } else {
+      return false;
+    }
+  }
+
+  return location;
+}
+
+// Find the package.json object of the module closest up the module call tree that contains name in that module's peerOptionalDependencies
+var find_package_json_with_name = function(name) {
+  // Walk up the module call tree until we find a module containing name in its peerOptionalDependencies
+  var currentModule = module;
+  var found = false;
+  while (currentModule) {
+    // Check currentModule has a package.json
+    location = currentModule.filename;
+    var location = find_package_json(location)
+    if (!location) {
+      currentModule = currentModule.parent;
+      continue;
+    }
+
+    // Read the package.json file
+    var object = JSON.parse(fs.readFileSync(f('%s/package.json', location)));
+    // Is the name defined by interal file references
+    var parts = name.split(/\//);
+
+    // Check whether this package.json contains peerOptionalDependencies containing the name we're searching for
+    if (!object.peerOptionalDependencies || (object.peerOptionalDependencies && !object.peerOptionalDependencies[parts[0]])) {
+      currentModule = currentModule.parent;
+      continue;
+    }
+    found = true;
+    break;
+  }
+
+  // Check whether name has been found in currentModule's peerOptionalDependencies
+  if (!found) {
+    throw new Error(f('no optional dependency [%s] defined in peerOptionalDependencies in any package.json', parts[0]));
+  }
+
+  return {
+    object: object,
+    parts: parts
+  }
+}
+
+var require_optional = function(name, options) {
+  options = options || {};
+  options.strict = typeof options.strict == 'boolean' ? options.strict : true;
+
+  var res = find_package_json_with_name(name)
+  var object = res.object;
+  var parts = res.parts;
+
+  // Unpack the expected version
+  var expectedVersions = object.peerOptionalDependencies[parts[0]];
+  // The resolved package
+  var moduleEntry = undefined;
+  // Module file
+  var moduleEntryFile = name;
+
+  try {
+    // Validate if it's possible to read the module
+    moduleEntry = require(moduleEntryFile);
+  } catch(err) {
+    // Attempt to resolve in top level package
+    try {
+      // Get the module entry file
+      moduleEntryFile = resolveFrom(process.cwd(), name);
+      if(moduleEntryFile == null) return undefined;
+      // Attempt to resolve the module
+      moduleEntry = require(moduleEntryFile);
+    } catch(err) {
+      if(err.code === 'MODULE_NOT_FOUND') return undefined;
+    }
+  }
+
+  // Resolve the location of the module's package.json file
+  var location = find_package_json(require.resolve(moduleEntryFile));
+  if(!location) {
+    throw new Error('package.json can not be located');
+  }
+
+  // Read the module file
+  var dependentOnModule = JSON.parse(fs.readFileSync(f('%s/package.json', location)));
+  // Get the version
+  var version = dependentOnModule.version;
+  // Validate if the found module satisfies the version id
+  if(semver.satisfies(version, expectedVersions) == false
+    && options.strict) {
+      var error = new Error(f('optional dependency [%s] found but version [%s] did not satisfy constraint [%s]', parts[0], version, expectedVersions));
+      error.code = 'OPTIONAL_MODULE_NOT_FOUND';
+      throw error;
+  }
+
+  // Satifies the module requirement
+  return moduleEntry;
+}
+
+require_optional.exists = function(name) {
+  try {
+    var m = require_optional(name);
+    if(m === undefined) return false;
+    return true;
+  } catch(err) {
+    return false;
+  }
+}
+
+module.exports = require_optional;