+++ /dev/null
-[](http://ejdb.org)
-
-
-Embedded JSON Database engine
-====================================
-
-It aims to be a fast [MongoDB](http://mongodb.org)-like library **which can be embedded into C/C++, .Net, NodeJS, Python, Lua, Go, Java and Ruby applications under terms of LGPL license.**
-
-EJDB is the C library based on modified version of [Tokyo Cabinet](http://fallabs.com/tokyocabinet/).
-
-JSON representation of queries and data implemented with API based on [C BSON](https://github.com/mongodb/mongo-c-driver/tree/master/src/)
-
-News
-===============================
-* `2013-09-20` **[EJDB Matlab binding from Kota Yamaguchi] (https://github.com/kyamagu/matlab-ejdb)**
-* `2013-09-10` **[v1.1.24 Fixed incorrect $set behaviour] (https://github.com/Softmotions/ejdb/wiki/V1.1.24)**
-* `2013-08-19` **[v1.1.19 Added support the long awaited mongodb update positional operator] (https://github.com/Softmotions/ejdb/wiki/V1.1.19)**
-* `2013-08-11` **[v1.1.18 Added support for mongodb $ projection] (https://github.com/Softmotions/ejdb/wiki/V1.1.18)**
-* `2013-08-08` **[v1.1.17 Now supported $and & $or mongodb operators] (https://github.com/Softmotions/ejdb/issues/81)**
-* `2013-07-15` **[Google Go binding] (https://github.com/mkilling/goejdb)**
-* `2013-06-23` **[C# .Net binding] (https://github.com/Softmotions/ejdb-csharp)**
-* `2013-06-02` **[Adobe Air Native Extension (ANE) for EJDB (Thanks to @thejustinwalsh)] (https://github.com/thejustinwalsh/airejdb)**
-* `2013-05-29` **[EJDB Python 2.7.x binding available](https://github.com/Softmotions/ejdb-python)**
-* `2013-05-06` **[Ruby binding available](https://github.com/Softmotions/ejdb-ruby)**
-* `2013-05-02` **[NodeJS win32 module available](https://github.com/Softmotions/ejdb/blob/master/tcejdb/WIN32.md#ejdb-nodejs-module-installation)**
-* `2013-04-25` **[EJDB and TokyoCabinet API ported to Windows](https://github.com/Softmotions/ejdb/blob/master/tcejdb/WIN32.md)**
-* `2013-04-03` **[Java API binding available](https://github.com/Softmotions/ejdb-java)**
-* `2013-03-20` **[Lua binding available](https://github.com/Softmotions/ejdb-lua/)**
-* `2013-02-15` **[EJDB Python3 binding available](https://github.com/Softmotions/ejdb-python)**
-* `2013-02-07` **[Debian packages provided](https://github.com/Softmotions/ejdb/wiki/Debian-Ubuntu-installation)**
-* `2013-01-22` **[Collection joins now supported](https://github.com/Softmotions/ejdb/wiki/Collection-joins)**
-
-Features
-================================
-* LGPL license allows you to embed this library into proprietary software.
-* [EJDB and TokyoCabinet API ported to Windows](https://github.com/Softmotions/ejdb/blob/master/tcejdb/WIN32.md)
-* MongoDB-like queries and overall philosophy.
-* [Collection joins](https://github.com/Softmotions/ejdb/wiki/Collection-joins)
-* Collection level write locking.
-* Collection level transactions.
-* Node.js/Python/Lua/Java/Ruby/.Net/Go bindings
-* [Adobe Air Native Extension (ANE) for EJDB] (https://github.com/thejustinwalsh/airejdb)
-* [Pike language binding] (https://github.com/hww3/pike_modules-ejdb)
-
-Documentation
-================================
-
-* **[The brief intro to the EJDB](http://blog.abigopal.com/post/51616277039/ejdb)**
-* **[EJDB Command line interface](https://github.com/Softmotions/ejdb/wiki/EJDB-Command-line-interface)**
-* **[EJDB C Library](#ejdb-c-library)**
- * [Building & Installation](#building--installation)
- * [Samples](#ejdb-c-samples)
- * [C API](#c-api)
-* **[Data Import/Export](https://github.com/Softmotions/ejdb/wiki/Data-Import-Export)**
-* **[Collection joins](https://github.com/Softmotions/ejdb/wiki/Collection-joins)**
-* **[Development FAQ](https://github.com/Softmotions/ejdb/wiki/Development-FAQ)**
-* **Bindings**
- * **[C# .Net] (https://github.com/Softmotions/ejdb-csharp)**
- * **[NodeJS] (https://github.com/Softmotions/ejdb-node)**
- * **[Python 2.7/3.x](https://github.com/Softmotions/ejdb-python)**
- * **[Lua](https://github.com/Softmotions/ejdb-lua/)**
- * **[Java](https://github.com/Softmotions/ejdb-java)**
- * **[Ruby](https://github.com/Softmotions/ejdb-ruby)**
- * **[Objective-C](https://github.com/johnnyd/EJDBKit)**
- * **[Go](https://github.com/mkilling/goejdb/)**
- * **[Pike language] (https://github.com/hww3/pike_modules-ejdb)**
- * **[Adobe Air] (https://github.com/thejustinwalsh/airejdb)**
- * **[Matlab] (https://github.com/kyamagu/matlab-ejdb)**
-
-
-
-Community
-================================
-* **[ejdblab@twitter.com](https://twitter.com/ejdblab)**
-* **We use [EJDB Google group](http://groups.google.com/group/ejdb) as our mailing list.**
-* [Projects using EJDB](https://github.com/Softmotions/ejdb/wiki/Projects-using-EJDB)
-
-EJDB NodeJS
-=================================
-
-One snippet intro
----------------------------------
-
-```JavaScript
-var EJDB = require("ejdb");
-//Open zoo DB
-var jb = EJDB.open("zoo", EJDB.DEFAULT_OPEN_MODE | EJDB.JBOTRUNC);
-
-var parrot1 = {
- "name" : "Grenny",
- "type" : "African Grey",
- "male" : true,
- "age" : 1,
- "birthdate" : new Date(),
- "likes" : ["green color", "night", "toys"],
- "extra1" : null
-};
-var parrot2 = {
- "name" : "Bounty",
- "type" : "Cockatoo",
- "male" : false,
- "age" : 15,
- "birthdate" : new Date(),
- "likes" : ["sugar cane"]
-};
-
-jb.save("parrots", [parrot1, parrot2], function(err, oids) {
- if (err) {
- console.error(err);
- return;
- }
- console.log("Grenny OID: " + parrot1["_id"]);
- console.log("Bounty OID: " + parrot2["_id"]);
-
- jb.find("parrots",
- {"likes" : "toys"},
- {"$orderby" : {"name" : 1}},
- function(err, cursor, count) {
- if (err) {
- console.error(err);
- return;
- }
- console.log("Found " + count + " parrots");
- while (cursor.next()) {
- console.log(cursor.field("name") + " likes toys!");
- }
- cursor.close(); //It's not mandatory to close cursor explicitly
- jb.close(); //Close the database
- });
-});
-```
-**[EJDB NodeJS binding page](https://github.com/Softmotions/ejdb-node)**
-
-EJDB Python
-==================================
-
-One snippet intro
----------------------------------
-
-```python
-import pyejdb
-from datetime import datetime
-
-#Open database
-ejdb = pyejdb.EJDB("zoo", pyejdb.DEFAULT_OPEN_MODE | pyejdb.JBOTRUNC)
-
-parrot1 = {
- "name": "Grenny",
- "type": "African Grey",
- "male": True,
- "age": 1,
- "birthdate": datetime.utcnow(),
- "likes": ["green color", "night", "toys"],
- "extra1": None
-}
-parrot2 = {
- "name": "Bounty",
- "type": "Cockatoo",
- "male": False,
- "age": 15,
- "birthdate": datetime.utcnow(),
- "likes": ["sugar cane"],
- "extra1": None
-}
-ejdb.save("parrots2", parrot1, parrot2)
-
-with ejdb.find("parrots2", {"likes" : "toys"},
- hints={"$orderby" : [("name", 1)]}) as cur:
- print("found %s parrots" % len(cur))
- for p in cur:
- print("%s likes toys!" % p["name"])
-
-ejdb.close()
-```
-**[EJDB Python 2.7/3.x binding page](https://github.com/Softmotions/ejdb-python)**
-
-EJDB Lua
-==================================
-
-One snippet intro
----------------------------------
-
-```lua
-local ejdb = require("ejdb")
-local inspect = require("ejdb.inspect")
-local Q = ejdb.Q
-
--- Used modes:
--- 'r' - read
--- 'w' - write
--- 'c' - create db if not exists
--- 't' - truncate existing db
-local db = ejdb.open("zoo", "rwct")
-
--- Unordered lua table
-local parrot1 = {
- name = "Grenny",
- type = "African Grey",
- male = true,
- age = 1,
- birthhdate = ejdb.toDateNow(),
- likes = { "green color", "night", "toys" },
- extra1 = ejdb.toNull()
-}
-
--- Preserve order of BSON keys
-local parrot2 = Q();
-parrot2:KV("name", "Bounty"):KV("type", "Cockatoo"):KV("male", false)
-parrot2:KV("age", 15):KV("birthdate",
- ejdb.toDate({ year = 2013, month = 1, day = 1, hour = 0, sec = 1 }))
-parrot2:KV("likes", { "sugar cane" }):KV("extra1", ejdb.toNull())
-
---IF YOU WANT SOME DATA INSPECTIONS:
---print(ejdb.print_bson(parrot2:toBSON()))
---local obj = ejdb.from_bson(parrot2:toBSON())
---print(inspect(obj));
-
-db:save("parrots2", parrot1)
-db:save("parrots2", parrot2)
-
--- Below two equivalent queries:
--- Q1
-local res, count, log =
-db:find("parrots2", Q("likes", "toys"):OrderBy("name asc", "age desc"))
-for i = 1, #res do -- iterate one
- local ob = res:object(i)
- print("" .. ob["name"] .. " likes toys #1")
-end
-
--- Q2
-local res, count, log =
-db:find("parrots2", Q():F("likes"):Eq("toys"):OrderBy({ name = 1 }, { age = -1 }))
-for i = 1, #res do -- iterate one
- print("" .. res:field(i, "name") .. " likes toys #2")
-end
-
--- Second way to iterate
-for vobj, idx in res() do
- print("" .. vobj["name"] .. " likes toys #3")
-end
-
-db:close()
-```
-**[EJDB Lua binding page](https://github.com/Softmotions/ejdb-lua)**
-
-EJDB Go
-==================================
-
-One snippet intro
------------------------------------
-
-```go
-package ejdbtutorial
-
-import (
- "fmt"
- "github.com/mkilling/goejdb"
- "labix.org/v2/mgo/bson"
- "os"
-)
-
-func main() {
- // Create a new database file and open it
- jb, err := goejdb.Open("addressbook", JBOWRITER | JBOCREAT | JBOTRUNC)
- if err != nil {
- os.Exit(1)
- }
- // Get or create collection 'contacts'
- coll, _ := jb.CreateColl("contacts", nil)
-
- // Insert one record:
- // JSON: {'name' : 'Bruce', 'phone' : '333-222-333', 'age' : 58}
- rec := map[string]interface{} {"name" : "Bruce", "phone" : "333-222-333", "age" : 58}
- bsrec, _ := bson.Marshal(rec)
- coll.SaveBson(bsrec)
- fmt.Printf("\nSaved Bruce")
-
- // Now execute query
- res, _ := coll.Find(`{"name" : {"$begin" : "Bru"}}`) // Name starts with 'Bru' string
- fmt.Printf("\n\nRecords found: %d\n", len(res))
-
- // Now print the result set records
- for _, bs := range res {
- var m map[string]interface{}
- bson.Unmarshal(bs, &m)
- fmt.Println(m)
- }
-
- // Close database
- jb.Close()
-}
-```
-**[EJDB Go binding page](https://github.com/mkilling/goejdb)**
-
-
-EJDB Ruby
-==================================
-
-One snippet intro
----------------------------------
-
-```Ruby
-require "rbejdb"
-
-#Open zoo DB
-jb = EJDB.open("zoo", EJDB::DEFAULT_OPEN_MODE | EJDB::JBOTRUNC)
-
-parrot1 = {
- "name" => "Grenny",
- "type" => "African Grey",
- "male" => true,
- "age" => 1,
- "birthdate" => Time.now,
- "likes" => ["green color", "night", "toys"],
- "extra1" => nil
-}
-parrot2 = {
- "name" => "Bounty",
- "type" => "Cockatoo",
- "male" => false,
- "age" => 15,
- "birthdate" => Time.now,
- "likes" => ["sugar cane"],
- "extra1" => nil
-}
-
-jb.save("parrots", parrot1, parrot2)
-puts "Grenny OID: #{parrot1["_id"]}"
-puts "Bounty OID: #{parrot2["_id"]}"
-
-results = jb.find("parrots", {"likes" => "toys"}, {"$orderby" => {"name" => 1}})
-
-puts "Found #{results.count} parrots"
-
-results.each { |res|
- puts "#{res['name']} likes toys!"
-}
-
-results.close #It's not mandatory to close cursor explicitly
-jb.close #Close the database
-
-```
-**[EJDB Ruby binding page](https://github.com/Softmotions/ejdb-ruby)**
-
-
-EJDB Adobe AIR
-==================================
-
-One snippet intro
----------------------------------
-
-```as3
-// Open the zoo DB
-var db:EJDBDatabase = EJDB.open("zoo", EJDB.DEFAULT_OPEN_MODE | EJDB.JBOTRUNC) as EJDBDatabase;
-
-var parrot1:Object = {
- "name" : "Grenny",
- "type" : "African Grey",
- "male" : true,
- "age" : 1,
- "birthdate" : new Date(),
- "likes" : ["green color", "night", "toys"],
- "extra1" : null
-};
-var parrot2:Object = {
- "name" : "Bounty",
- "type" : "Cockatoo",
- "male" : false,
- "age" : 15,
- "birthdate" : new Date(),
- "likes" : ["sugar cane"]
-};
-
-var oids:Array = db.save("parrots", [parrot1, parrot2]);
-trace("Grenny OID: " + parrot1._id);
-trace("Bounty OID: " + parrot2._id);
-
-var cursor:EJDBCursor = db.find("parrots",
- {"likes" : "toys"},
- [],
- {"$orderby" : {"name" : 1}}
-);
-
-trace("Found " + cursor.length + " parrots");
-while (cursor.next()) {
- trace(cursor.field("name") + " likes toys!");
-}
-
-cursor.close(); // It IS mandatory to close cursor explicitly to free up resources
-db.close(); // Close the database
-```
-**[Adobe Air Native Extension (ANE) for EJDB] (https://github.com/thejustinwalsh/airejdb)**
-
-EJDB C Library
-==================================
-
-One snippet intro
------------------------------------
-
-```C
-#include <tcejdb/ejdb.h>
-
-static EJDB *jb;
-
-int main() {
- jb = ejdbnew();
- if (!ejdbopen(jb, "addressbook", JBOWRITER | JBOCREAT | JBOTRUNC)) {
- return 1;
- }
- //Get or create collection 'contacts'
- EJCOLL *coll = ejdbcreatecoll(jb, "contacts", NULL);
-
- bson bsrec;
- bson_oid_t oid;
-
- //Insert one record:
- //JSON: {'name' : 'Bruce', 'phone' : '333-222-333', 'age' : 58}
- bson_init(&bsrec);
- bson_append_string(&bsrec, "name", "Bruce");
- bson_append_string(&bsrec, "phone", "333-222-333");
- bson_append_int(&bsrec, "age", 58);
- bson_finish(&bsrec);
- //Save BSON
- ejdbsavebson(coll, &bsrec, &oid);
- fprintf(stderr, "\nSaved Bruce");
- bson_destroy(&bsrec);
-
- //Now execute query
- //QUERY: {'name' : {'$begin' : 'Bru'}} //Name starts with 'Bru' string
- bson bq1;
- bson_init_as_query(&bq1);
- bson_append_start_object(&bq1, "name");
- bson_append_string(&bq1, "$begin", "Bru");
- bson_append_finish_object(&bq1);
- bson_finish(&bq1);
-
- EJQ *q1 = ejdbcreatequery(jb, &bq1, NULL, 0, NULL);
-
- uint32_t count;
- TCLIST *res = ejdbqryexecute(coll, q1, &count, 0, NULL);
- fprintf(stderr, "\n\nRecords found: %d\n", count);
-
- //Now print the result set records
- for (int i = 0; i < TCLISTNUM(res); ++i) {
- void *bsdata = TCLISTVALPTR(res, i);
- bson_print_raw(bsdata, 0);
- }
- fprintf(stderr, "\n");
-
- //Dispose result set
- tclistdel(res);
-
- //Dispose query
- ejdbquerydel(q1);
- bson_destroy(&bq1);
-
- //Close database
- ejdbclose(jb);
- ejdbdel(jb);
- return 0;
-}
-```
-
-You can save this code in `csnippet.c` And build:
-
-```sh
-gcc -std=c99 -Wall -pedantic -c -o csnippet.o csnippet.c
-gcc -o csnippet csnippet.o -ltcejdb
-```
-
-Building & Installation
---------------------------------
- * [Installation on windows](https://github.com/Softmotions/ejdb/blob/master/tcejdb/WIN32.md)
- * [Installation on Debian/Ubuntu](https://github.com/Softmotions/ejdb/wiki/Debian-Ubuntu-installation)
- * Installation on OS X 10.7+ using [Homebrew](http://brew.sh/): `brew install ejdb`
-
-Manual installation
--------------------------------
-
-### Prerequisites
-**System libraries:**
-
-* gcc
-* zlib-dev
-
-### Build and install
-
-```sh
- cd ./tcejdb
- ./configure --prefix=<installation prefix> && make && make check
- make install
-```
-* library name: **tcejdb** (with pkgconfig)
-* main include header: ```<tcejdb/ejdb.h>```
-
-C API
----------------------------------
-EJDB API presented in **[ejdb.h](https://github.com/Softmotions/ejdb/blob/master/tcejdb/ejdb.h)** C header file.
-
-JSON processing API: **[bson.h](https://github.com/Softmotions/ejdb/blob/master/tcejdb/bson.h)**
-
-Queries
----------------------------------
-
-~~~~~~
-/**
- * Create query object.
- * Sucessfully created queries must be destroyed with ejdbquerydel().
- *
- * EJDB queries inspired by MongoDB (mongodb.org) and follows same philosophy.
- *
- * - Supported queries:
- * - Simple matching of String OR Number OR Array value:
- * - {'fpath' : 'val', ...}
- * - $not Negate operation.
- * - {'fpath' : {'$not' : val}} //Field not equal to val
- * - {'fpath' : {'$not' : {'$begin' : prefix}}} //Field not begins with val
- * - $begin String starts with prefix
- * - {'fpath' : {'$begin' : prefix}}
- * - $gt, $gte (>, >=) and $lt, $lte for number types:
- * - {'fpath' : {'$gt' : number}, ...}
- * - $bt Between for number types:
- * - {'fpath' : {'$bt' : [num1, num2]}}
- * - $in String OR Number OR Array val matches to value in specified array:
- * - {'fpath' : {'$in' : [val1, val2, val3]}}
- * - $nin - Not IN
- * - $strand String tokens OR String array val matches all tokens in specified array:
- * - {'fpath' : {'$strand' : [val1, val2, val3]}}
- * - $stror String tokens OR String array val matches any token in specified array:
- * - {'fpath' : {'$stror' : [val1, val2, val3]}}
- * - $exists Field existence matching:
- * - {'fpath' : {'$exists' : true|false}}
- * - $icase Case insensitive string matching:
- * - {'fpath' : {'$icase' : 'val1'}} //icase matching
- * Ignore case matching with '$in' operation:
- * - {'name' : {'$icase' : {'$in' : ['tHéâtre - театр', 'heLLo WorlD']}}}
- * For case insensitive matching you can create special index of type: `JBIDXISTR`
- * - $elemMatch The $elemMatch operator matches more than one component within an array element.
- * - { array: { $elemMatch: { value1 : 1, value2 : { $gt: 1 } } } }
- * Restriction: only one $elemMatch allowed in context of one array field.
- * - $and, $or joining:
- * - {..., $and : [subq1, subq2, ...] }
- * - {..., $or : [subq1, subq2, ...] }
- * Example: {z : 33, $and : [ {$or : [{a : 1}, {b : 2}]}, {$or : [{c : 5}, {d : 7}]} ] }
- *
- * - Mongodb $(projection) operator supported. (http://docs.mongodb.org/manual/reference/projection/positional/#proj._S_)
- * - Mongodb positional $ update operator supported. (http://docs.mongodb.org/manual/reference/operator/positional/)
- *
- *
- * - Queries can be used to update records:
- * $set Field set operation.
- * - {.., '$set' : {'field1' : val1, 'fieldN' : valN}}
- * $upsert Atomic upsert. If matching records are found it will be '$set' operation,
- * otherwise new record will be inserted with fields specified by argment object.
- * - {.., '$upsert' : {'field1' : val1, 'fieldN' : valN}}
- * $inc Increment operation. Only number types are supported.
- * - {.., '$inc' : {'field1' : number, ..., 'field1' : number}
- * $dropall In-place record removal operation.
- * - {.., '$dropall' : true}
- * $addToSet Atomically adds value to the array only if its not in the array already.
- * If containing array is missing it will be created.
- * - {.., '$addToSet' : {'fpath' : val1, 'fpathN' : valN, ...}}
- * $addToSetAll Batch version if $addToSet
- * - {.., '$addToSetAll' : {'fpath' : [array of values to add], ...}}
- * $pull Atomically removes all occurrences of value from field, if field is an array.
- * - {.., '$pull' : {'fpath' : val1, 'fpathN' : valN, ...}}
- * $pullAll Batch version of $pull
- * - {.., '$pullAll' : {'fpath' : [array of values to remove], ...}}
- * $rename Rename field operation
- * - {.., '$rename' : {'oldfname1' : 'newfname1', 'oldfnameN' : 'newfnameN'}}
- * $unset Unset the specified fields
- * - { $unset: { 'fpath1' : "", ... } }
- * $slice Array field slice operator (like a mongodb $slice) implemented within $do operation.
- * - ${..., $do : {'fpath1' : {$slice : <limit>}}
- * - ${..., $do : {'fpath1' : {$slice : [<offset>, <limit>]}}
- *
- * NOTE: Negate operations: $not and $nin not using indexes
- * so they can be slow in comparison to other matching operations.
- *
- * NOTE: Only one index can be used in search query operation.
- *
- * QUERY HINTS (specified by `hints` argument):
- * - $max Maximum number in the result set
- * - $skip Number of skipped results in the result set
- * - $orderby Sorting order of query fields.
- * - $fields Set subset of fetched fields
- If a field presented in $orderby clause it will be forced to include in resulting records.
- * Example:
- * hints: {
- * "$orderby" : { //ORDER BY field1 ASC, field2 DESC
- * "field1" : 1,
- * "field2" : -1
- * },
- * "$fields" : { //SELECT ONLY {_id, field1, field2}
- * "field1" : 1,
- * "field2" : 1
- * }
- * }
- *
- * Many query examples can be found in `testejdb/t2.c` test case.
- *
- * @param EJDB database handle.
- * @param qobj Main BSON query object.
- * @param orqobjs Array of additional OR query objects (joined with OR predicate).
- * @param orqobjsnum Number of OR query objects.
- * @param hints BSON object with query hints.
- * @return On success return query handle. On error returns NULL.
- */
-EJDB_EXPORT EJQ* ejdbcreatequery(EJDB *jb, bson *qobj, bson *orqobjs, int orqobjsnum, bson *hints);
-~~~~~~
-
-EJDB C Samples
-------------------------------------
-You can find some code samples in:
-
-* [tcejdb/samples](https://github.com/Softmotions/ejdb/tree/master/tcejdb/samples)
-* [tcejdb/testejdb](https://github.com/Softmotions/ejdb/tree/master/tcejdb/testejdb)
-
-Basic EJDB architecture
-------------------------------------
-**EJDB database files structure**
-
-~~~~~~
-.
-├── <dbname>
-├── <dbname>_<collection1>
-├── ...
-├── <dbname>_<collectionN>
-└── <dbname>_<collectionN>_<fieldpath>.<index ext>
-~~~~~~
-
-Where
-
-* ```<dbname>``` - name of database. It is metadata DB.
-* ```<collectionN>``` - name of collection. Collection database.
-* ```<fieldpath>``` - JSON field path used in index
-* ```<index ext>``` - Collection index extension:
- * ```.lex``` String index
- * ```.dec``` Number index
- * ```.tok``` Array index
-
-Limitations
-------------------------------------
-* One ejdb database can handle up to 1024 collections.
-* Indexes for objects in nested arrays currently not supported (#37)
-
-TODO
-------------------------------------
-* Collect collection index statistic
projects / platform / upstream / ejdb.git / commitdiff