nconf-lite/lib/nconf/provider.js

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4.4 KiB
JavaScript

/*
* provider.js: Abstraction providing an interface into pluggable configuration storage.
*
* (C) 2011, Charlie Robbins
*
*/
var stores = require('./stores');
//
// ### function Provider (options)
// #### @options {Object} Options for this instance.
// Constructor function for the Provider object responsible
// for exposing the pluggable storage features of `nconf`.
//
var Provider = exports.Provider = function (options) {
options = options || {};
this.store = stores.create(options.type || 'memory', options);
};
//
// ### function use (type, options)
// #### @type {string} Type of the nconf store to use.
// #### @options {Object} Options for the store instance.
// Sets the active `this.store` to a new instance of the
// specified `type`.
//
Provider.prototype.use = function (type, options) {
var self = this;
options = options || {};
function sameOptions () {
return Object.keys(options).every(function (key) {
return options[key] === self.store[key];
});
}
if (!this.store || type.toLowerCase() !== this.store.type
|| !sameOptions()) {
this.store = stores.create(type, options);
}
return this;
};
//
// ### function get (key, callback)
// #### @key {string} Key to retrieve for this instance.
// #### @callback {function} **Optional** Continuation to respond to when complete.
// Retrieves the value for the specified key (if any).
//
Provider.prototype.get = function (key, callback) {
return this.store.get(key, callback);
};
//
// ### function set (key, value, callback)
// #### @key {string} Key to set in this instance
// #### @value {literal|Object} Value for the specified key
// #### @callback {function} **Optional** Continuation to respond to when complete.
// Sets the `value` for the specified `key` in this instance.
//
Provider.prototype.set = function (key, value, callback) {
return this.store.set(key, value, callback);
};
//
// ### function merge (key, value)
// #### @key {string} Key to merge the value into
// #### @value {literal|Object} Value to merge into the key
// Merges the properties in `value` into the existing object value
// at `key`. If the existing value `key` is not an Object, it will be
// completely overwritten.
//
Provider.prototype.merge = function (key, value, callback) {
return this.store.merge(key, value, callback);
}
//
// ### function clear (key, callback)
// #### @key {string} Key to remove from this instance
// #### @callback {function} **Optional** Continuation to respond to when complete.
// Removes the value for the specified `key` from this instance.
//
Provider.prototype.clear = function (key, callback) {
return this.store.clear(key, callback);
};
//
// ### function load (callback)
// #### @callback {function} Continuation to respond to when complete.
// Responds with an Object representing all keys associated in this instance.
//
Provider.prototype.load = function (callback) {
//
// If we don't have a callback and the current
// store is capable of loading synchronously
// then do so.
//
if (!callback && this.store.loadSync) {
return this.store.loadSync();
}
if (!this.store.load) {
var error = new Error('nconf store ' + this.store.type + ' has no load() method');
if (callback) {
return callback (error);
}
throw error;
}
return this.store.load(callback);
};
//
// ### function save (value, callback)
// #### @value {Object} **Optional** Config object to set for this instance
// #### @callback {function} Continuation to respond to when complete.
// Removes any existing configuration settings that may exist in this
// instance and then adds all key-value pairs in `value`.
//
Provider.prototype.save = function (value, callback) {
if (!callback) {
callback = value;
value = null;
//
// If we still don't have a callback and the
// current store is capable of saving synchronously
// then do so.
//
if (!callback && this.store.saveSync) {
return this.store.saveSync();
}
}
if (!this.store.save) {
var error = new Error('nconf store ' + this.store.type + ' has no save() method');
if (callback) {
return callback (error);
}
throw error;
}
return this.store.save(value, callback);
};
//
// ### function reset (callback)
// #### @callback {function} **Optional** Continuation to respond to when complete.
// Clears all keys associated with this instance.
//
Provider.prototype.reset = function (callback) {
return this.store.reset(callback);
};