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| /**
Memory Backend.
In-memory implementation of the storage.
*/
"use strict";
var
contract = require('./contract'),
_ = require('lodash');
function MemoryBackend(){
this._buckets = {};
};
MemoryBackend.prototype = {
/**
Begins a transaction.
*/
begin : function(){
// returns a transaction object(just an array of functions will do here.)
return [];
},
/**
Ends a transaction (and executes it)
*/
end : function(transaction, cb){
contract(arguments).params('array', 'function').end();
// Execute transaction
for(var i=0, len=transaction.length;i<len;i++){
transaction[i]();
}
cb();
},
/**
Cleans the whole storage.
*/
clean : function(cb){
contract(arguments).params('function').end();
this._buckets = {};
cb();
},
/**
Gets the contents at the bucket's key.
*/
get : function(bucket, key, cb){
contract(arguments)
.params('string', 'string', 'function')
.end();
Eif(this._buckets[bucket]){
cb(null, this._buckets[bucket][key] || []);
}else{
cb(null, []);
}
},
/**
Returns the union of the values in the given keys.
*/
union : function(bucket, keys, cb){
contract(arguments)
.params('string', 'array', 'function')
.end();
Eif(this._buckets[bucket]){
var keyArrays = [];
for(var i=0,len=keys.length;i<len;i++){
if(this._buckets[bucket][keys[i]]){
keyArrays.push.apply(keyArrays, this._buckets[bucket][keys[i]]);
}
}
cb(undefined, _.union(keyArrays));
}else{
cb(undefined, []);
}
},
/**
Adds values to a given key inside a bucket.
*/
add : function(transaction, bucket, key, values){
contract(arguments)
.params('array', 'string', 'string','string|array')
.end();
var self = this;
values = makeArray(values);
transaction.push(function(){
if(!self._buckets[bucket]){
self._buckets[bucket] = {};
}
if(!self._buckets[bucket][key]){
self._buckets[bucket][key] = values;
}else{
self._buckets[bucket][key] = _.union(values, self._buckets[bucket][key]);
}
})
},
/**
Delete the given key(s) at the bucket
*/
del : function(transaction, bucket, keys){
contract(arguments)
.params('array', 'string', 'string|array')
.end();
var self = this;
keys = makeArray(keys);
transaction.push(function(){
Eif(self._buckets[bucket]){
for(var i=0, len=keys.length;i<len;i++){
delete self._buckets[bucket][keys[i]];
}
}
})
},
/**
Removes values from a given key inside a bucket.
*/
remove : function(transaction, bucket, key, values){
contract(arguments)
.params('array', 'string', 'string','string|array')
.end();
var self = this;
values = makeArray(values);
transaction.push(function(){
var old;
if(self._buckets[bucket] && (old = self._buckets[bucket][key])){
self._buckets[bucket][key] = _.difference(old, values);
}
});
},
}
function makeArray(arr){
return Array.isArray(arr) ? arr : [arr];
}
exports = module.exports = MemoryBackend;
|