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driver.go
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driver.go
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// Copyright (c) 2015-2016 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package database
import (
"fmt"
)
// Driver defines a structure for backend drivers to use when they registered
// themselves as a backend which implements the DB interface.
type Driver struct {
// DbType is the identifier used to uniquely identify a specific
// database driver. There can be only one driver with the same name.
DbType string
// Create is the function that will be invoked with all user-specified
// arguments to create the database. This function must return
// ErrDbExists if the database already exists.
Create func(args ...interface{}) (DB, error)
// Open is the function that will be invoked with all user-specified
// arguments to open the database. This function must return
// ErrDbDoesNotExist if the database has not already been created.
Open func(args ...interface{}) (DB, error)
}
// driverList holds all of the registered database backends.
var drivers = make(map[string]*Driver)
// RegisterDriver adds a backend database driver to available interfaces.
// ErrDbTypeRegistered will be retruned if the database type for the driver has
// already been registered.
func RegisterDriver(driver Driver) error {
if _, exists := drivers[driver.DbType]; exists {
str := fmt.Sprintf("driver %q is already registered",
driver.DbType)
return makeError(ErrDbTypeRegistered, str, nil)
}
drivers[driver.DbType] = &driver
return nil
}
// SupportedDrivers returns a slice of strings that represent the database
// drivers that have been registered and are therefore supported.
func SupportedDrivers() []string {
supportedDBs := make([]string, 0, len(drivers))
for _, drv := range drivers {
supportedDBs = append(supportedDBs, drv.DbType)
}
return supportedDBs
}
// Create initializes and opens a database for the specified type. The
// arguments are specific to the database type driver. See the documentation
// for the database driver for further details.
//
// ErrDbUnknownType will be returned if the the database type is not registered.
func Create(dbType string, args ...interface{}) (DB, error) {
drv, exists := drivers[dbType]
if !exists {
str := fmt.Sprintf("driver %q is not registered", dbType)
return nil, makeError(ErrDbUnknownType, str, nil)
}
return drv.Create(args...)
}
// Open opens an existing database for the specified type. The arguments are
// specific to the database type driver. See the documentation for the database
// driver for further details.
//
// ErrDbUnknownType will be returned if the the database type is not registered.
func Open(dbType string, args ...interface{}) (DB, error) {
drv, exists := drivers[dbType]
if !exists {
str := fmt.Sprintf("driver %q is not registered", dbType)
return nil, makeError(ErrDbUnknownType, str, nil)
}
return drv.Open(args...)
}