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Introduce Module trait to make create_module type safe

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This commit is contained in:
gwenn
2018-06-20 20:01:38 +02:00
parent 2a684384fd
commit afeb5d4d47
4 changed files with 141 additions and 75 deletions
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61
src/vtab/mod.rs
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@@ -40,20 +40,36 @@ use {str_to_cstring, Connection, Error, InnerConnection, Result};
// \-> if not eof { cursor.column or xrowid } else { cursor.xclose }
//
/// Virtual table instance trait.
pub trait VTab: Sized {
/// Module instance trait
pub trait Module {
type Aux;
type Cursor: VTabCursor;
type Table: VTab;
fn as_ptr(&self) -> *const ffi::sqlite3_module;
/// Create a new instance of a virtual table in response to a CREATE VIRTUAL TABLE statement.
/// The `db` parameter is a pointer to the SQLite database connection that is executing
/// the CREATE VIRTUAL TABLE statement.
unsafe fn create(db: *mut ffi::sqlite3, aux: *mut Self::Aux, args: &[&[u8]]) -> Result<Self> {
unsafe fn create(
db: *mut ffi::sqlite3,
aux: Option<&Self::Aux>,
args: &[&[u8]],
) -> Result<Self::Table> {
Self::connect(db, aux, args)
}
/// Similar to `create`. The difference is that `connect` is called to establish a new connection
/// to an _existing_ virtual table whereas `create` is called to create a new virtual table from scratch.
unsafe fn connect(db: *mut ffi::sqlite3, aux: *mut Self::Aux, args: &[&[u8]]) -> Result<Self>;
unsafe fn connect(
db: *mut ffi::sqlite3,
aux: Option<&Self::Aux>,
args: &[&[u8]],
) -> Result<Self::Table>;
}
/// Virtual table instance trait.
pub trait VTab: Sized {
type Cursor: VTabCursor;
/// Determine the best way to access the virtual table.
fn best_index(&self, info: &mut IndexInfo) -> Result<()>;
/// Create a new cursor used for accessing a virtual table.
@@ -291,34 +307,34 @@ impl<'a> Iterator for ValueIter<'a> {
impl Connection {
/// Register a virtual table implementation.
pub fn create_module<A>(
pub fn create_module<M: Module>(
&self,
module_name: &str,
module: *const ffi::sqlite3_module,
aux: Option<A>,
module: M,
aux: Option<M::Aux>,
) -> Result<()> {
self.db.borrow_mut().create_module(module_name, module, aux)
}
}
impl InnerConnection {
fn create_module<A>(
fn create_module<M: Module>(
&mut self,
module_name: &str,
module: *const ffi::sqlite3_module,
aux: Option<A>,
module: M,
aux: Option<M::Aux>,
) -> Result<()> {
let c_name = try!(str_to_cstring(module_name));
let r = match aux {
Some(aux) => {
let boxed_aux: *mut A = Box::into_raw(Box::new(aux));
let boxed_aux: *mut M::Aux = Box::into_raw(Box::new(aux));
unsafe {
ffi::sqlite3_create_module_v2(
self.db(),
c_name.as_ptr(),
module,
module.as_ptr(),
boxed_aux as *mut c_void,
Some(free_boxed_value::<A>),
Some(free_boxed_value::<M::Aux>),
)
}
}
@@ -326,7 +342,7 @@ impl InnerConnection {
ffi::sqlite3_create_module_v2(
self.db(),
c_name.as_ptr(),
module,
module.as_ptr(),
ptr::null_mut(),
None,
)
@@ -401,6 +417,7 @@ unsafe extern "C" fn free_boxed_value<T>(p: *mut c_void) {
macro_rules! init_module {
(
$module_name:ident,
$module:ident,
$vtab:ident,
$aux:ty,
$cursor:ty,
@@ -445,8 +462,9 @@ macro_rules! init_module {
// The xConnect and xCreate methods do the same thing, but they must be
// different so that the virtual table is not an eponymous virtual table.
create_or_connect!($vtab, $aux, $create, create);
create_or_connect!($module, $vtab, $aux, $create, create);
common_decl!(
$module,
$vtab,
$aux,
$cursor,
@@ -469,6 +487,7 @@ macro_rules! init_module {
macro_rules! eponymous_module {
(
$module_name:ident,
$module:ident,
$vtab:ident,
$aux:ty,
$cursor:ty,
@@ -513,6 +532,7 @@ macro_rules! eponymous_module {
};
common_decl!(
$module,
$vtab,
$aux,
$cursor,
@@ -532,7 +552,7 @@ macro_rules! eponymous_module {
} // eponymous_module macro end
macro_rules! create_or_connect {
($vtab:ident, $aux:ty, $create_or_connect:ident, $vtab_func:ident) => {
($module:ident, $vtab:ident, $aux:ty, $create_or_connect:ident, $module_func:ident) => {
unsafe extern "C" fn $create_or_connect(
db: *mut ffi::sqlite3,
aux: *mut c_void,
@@ -550,9 +570,9 @@ macro_rules! create_or_connect {
let args = slice::from_raw_parts(argv, argc as usize);
let vec = args
.iter()
.map(|&cs| CStr::from_ptr(cs).to_bytes())
.map(|&cs| CStr::from_ptr(cs).to_bytes()) // FIXME .to_str() -> Result<&str, Utf8Error>
.collect::<Vec<_>>();
match $vtab::$vtab_func(db, aux, &vec[..]) {
match $module::$module_func(db, aux.as_ref(), &vec[..]) {
Ok(vtab) => {
let boxed_vtab: *mut $vtab = Box::into_raw(Box::new(vtab));
*pp_vtab = boxed_vtab as *mut ffi::sqlite3_vtab;
@@ -575,6 +595,7 @@ macro_rules! create_or_connect {
macro_rules! common_decl {
(
$module:ident,
$vtab:ident,
$aux:ty,
$cursor:ty,
@@ -590,7 +611,7 @@ macro_rules! common_decl {
$column:ident,
$rowid:ident
) => {
create_or_connect!($vtab, $aux, $connect, connect);
create_or_connect!($module, $vtab, $aux, $connect, connect);
unsafe extern "C" fn $best_index(
vtab: *mut ffi::sqlite3_vtab,
info: *mut ffi::sqlite3_index_info,