Builtin and Library Functions and Methods

OQL provides a few builtin and library functions. The builtin functions are written in C++ and cannot be overriden while the library functions are written in OQL and may be redefined by the user. The code for the library functions can be found in the section The Standard Library Package. The EYEDB system classes object, database, connection and EyeDB contains builtin class and instance methods that can be accessed from OQL. Some of these methods are briefly introduced in this section.

Type Predicat Functions


is_int(x)		: returns true if x is an int

is_double(x)		: returns true if x isa double; otherwise, returns false

is_string(x)		: returns true if x isa string; otherwise, returns false

is_oid(x)		: returns true if x isan oid; otherwise, returns false

is_num(x)		: returns true if x isan number (int, float or char);otherwise, returns false

is_bool(x)		: returns true if x isa bool; otherwise, returns false

is_bag(x)		: returns true if x isa bag; otherwise, returns false

is_set(x)		: returns true if x isa set; otherwise, returns false

is_array(x)		: returns true if x isa array; otherwise, returns false

is_list(x)		: returns true if x isa list; otherwise, returns false

is_coll(x)		: returns true if x isa collection; otherwise, returns false

is_struct(x)		: returns true if x isa struct; otherwise, returns false

is_empty(x)		: returns true if x isnil; otherwise, returns false

Collection Conversion Functions

The collection conversion functions take one collection argument and convert this collection to another collection type and returns the converted collection.


toset(coll)		: converts coll to a set

tolist(coll)		: converts coll to a list

tobag(coll)		: converts coll to a bag

toarray(coll)		: converts coll to a array

listtoset(coll)		: checks that coll is a list then  converts coll to a set

bagtoset(coll)		: checks that coll is a bag then  converts coll to a set

arraytoset(coll)		: checks that coll is a array then  converts coll to a set

listtobag(coll)		: checks that coll is a list then  converts coll to a bag

settobag(coll)		: checks that coll is a set then  converts coll to a bag

arraytobag(coll)		: checks that coll is a array then  converts coll to a bag

bagtolist(coll)		: checks that coll is a bag then  converts coll to a list

settolist(coll)		: checks that coll is a set then  converts coll to a list

arraytolist(coll)		: checks that coll is a array then  converts coll to a list

bagtoarray(coll)		: checks that coll is a bag then  converts coll to a array

settoarray(coll)		: checks that coll is a set then  converts coll to a array

listtoarray(coll)		: checks that coll is a set then  converts coll to a array

Sort Functions

These functions are used to sort collection of sortable atom of homogeneous types: int, char, float or string.


sort(coll)		: coll must a be a collection of homogeneoussortable atoms;


sorts and returns this collection

rsort(coll)		: coll must a be a collection of homogeneoussortable atoms;


reverse sorts and returns this collection

isort(coll, idx)		: coll must a be a collection of listor array


of homogeneous sortable atoms;

idx must be of int type;


sorts the collection of collections according to the

#idx elementof the inner collection

risort(coll, idx)		: same as previous function, but perform a reverse sort

Collection Miscelleanous Functions


first(coll)		: returns the first element of coll

car(coll)		: returns the first element of coll

last(coll)		: returns the last element of coll

cdr(coll)		: returns all elements of coll but the first

getn(coll, n)		: returns at most n elements of coll

count(coll)		: returns the count of elements of coll


identical to coll[!], but less efficient

sum(coll)		: returns the sum of the numbers of coll

avg(coll)		: returns the float average of the numbers coll

distinct(coll)		: eliminates duplicates of coll

flatten(coll)		: recursive flattening of coll

flatten1(coll)		: one level flattening of coll

min(coll)		: returns the minimal number of coll

max(coll)		: returns the maximal number of coll

forone(coll, f, data)		: if f(e, data) for one elemente


of coll, returns true;


otherwise returns false;

forall(coll, f, data)		: if f(e, data) for all elemente


of coll, returns true;


otherwiser returns false;

String Function Functions


tolower(str)		: converts (and returns) string str into lowercase

toupper(str)		: converts (and returns) string str into uppercase

tocap(str)		: converts the first character and each characterfollowing


a _ of str into an uppercase

strlen(str)		: returns the length of str;


same as str[!], but less efficient

substring(str, from, len)		: returns the sub-string of str


from the #from to the

from+len characters;


same as str[from:from+len] but less efficient

Query Functions


delete_from(class)		: deletes all the instances of a given class

get_from(class)		: gets all the instances of a given class

Useful Functions


assert(cond)		: throws an exception is cond is not true

assert_msg(cond, msg)		: throws the exception message msg if cond is not true

interval(from, to)		: returns a list composed of the numberfrom from to to

Native Methods of the Class `object`

The native methods of the class object allows us to perform a few action such as getting the oid of an instance getOid(), getting the database of an instance getDatabase() or converts the instance to its string representation toString(). For instance, to apply this last method to the first Person instance: first(select Person).toString().

All the native methods of the class object are instance methods.


oid getOid()		 : returns the oid of the object

string toString()		 : returns the string representation of the object

database *getDatabase()		 : returns the database instance ofthe object

void setDatabase(in database *)		 : changes the database of the object

void store()		 : stores the object in the database 

object *clone()		 : clones the object; returns the clone 

int getCTime()		 : returns the creation time of the object (seconds from 1/1/1970)

int getMTime()		 : returns the last modification time of the object

string getStringCTime()		 : returns the string representation ofthe creation time of the object

string getStringMTime()		 : returns the string representation ofthe creation time of the object

bool isRemoved()		 : returns true if the object is removed;false otherwise

bool isModify()		 :  returns true if the object is modified;false otherwise

Native Methods of the Class `connection`

All the native methods of the class connection are instance methods. an object obtained using the new operator, They can be applied on a database object that can be either the current connection oql$db->getConnection() either an object obtained using the new operator, for instance: new <> connection().


void open()		 : opens a new connection with default host and port

void open(in string host, in string port)		 : opens a new connectionusing host and port

void close()		 : closes the connection

Native Methods of the Class `database`

The following methods are the instance methods of the class database: They can be applied on a database object that can be either oql$db either an object obtained using the new operator, for instance: new <> database(name : "foo").


void open(		in connection *conn,

in int mode)		 : opens a new database using the connection

conn and the open flag mode mode

void open(		in connection *conn,

in int mode, 

in string userauth,

in string passwdauth)		 :  opens a new database using the connection conn,


the open flag mode mode and the authentication

userauth/passwdauth

void close()				 : closes the database

connection *getConnection()				: returns the connection tied tothe database

int getOpenMode()				: returns the open flag mode of the database

int getVersionNumber()				 : returns the version number of the database

string getVersion()				 : returns the string version of the database



void removeObject(in oid)				 : removes the object whose oid is given



void transactionBegin()				 : begins a new transaction

void transactionBegin(in string mode)				 : begins a new transactionin mode mode

void transactionCommit()				 : commits the current transaction

void transactionAbort()				 : abort the current transaction



bool isInTransaction()				 : returns true ifa transaction is in progress;

false otherwiser

Native Methods of the Class `EyeDB`

All the native methods of the class EyeDB are class methods.


string getConfigValue(in string s)		 : returns thestring value of the configuration variable s

int getVersionNumber()		 : returns the EYEDB current version number

string getVersion()		 : returns the EYEDB current stringversion

string getArchitecture()		 : returns the architecture of the current server

string getDefaultCompiler()		 : returns the C++ compiler used tocompile the current server

EyeDB manual