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VTabCursor lifetime should be bound to VTab lifetime

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```c
struct sqlite3_vtab_cursor {
  sqlite3_vtab *pVtab;      /* Virtual table of this cursor */
```
It seems that we need to introduce a lifetime on `VTab` trait
to express such constraint:
https://users.rust-lang.org/t/associated-type-with-lifetime-bound/7256
But there may be another/new way to do it.
This commit is contained in:
gwenn
2020-06-01 09:48:49 +02:00
parent 48a15857fb
commit 2af75d1f13
5 changed files with 74 additions and 56 deletions
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54
src/vtab/mod.rs
View File

@@ -61,13 +61,13 @@ use crate::{str_to_cstring, Connection, Error, InnerConnection, Result};
///
/// (See [SQLite doc](https://sqlite.org/c3ref/module.html))
#[repr(transparent)]
pub struct Module<T: VTab> {
pub struct Module<'vtab, T: VTab<'vtab>> {
base: ffi::sqlite3_module,
phantom: PhantomData<T>,
phantom: PhantomData<&'vtab T>,
}
unsafe impl<T: VTab> Send for Module<T> {}
unsafe impl<T: VTab> Sync for Module<T> {}
unsafe impl<'vtab, T: VTab<'vtab>> Send for Module<'vtab, T> {}
unsafe impl<'vtab, T: VTab<'vtab>> Sync for Module<'vtab, T> {}
union ModuleZeroHack {
bytes: [u8; std::mem::size_of::<ffi::sqlite3_module>()],
@@ -87,7 +87,7 @@ const ZERO_MODULE: ffi::sqlite3_module = unsafe {
/// `feature = "vtab"` Create a read-only virtual table implementation.
///
/// Step 2 of [Creating New Virtual Table Implementations](https://sqlite.org/vtab.html#creating_new_virtual_table_implementations).
pub fn read_only_module<T: CreateVTab>() -> &'static Module<T> {
pub fn read_only_module<'vtab, T: CreateVTab<'vtab>>() -> &'static Module<'vtab, T> {
// 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.
&Module {
@@ -118,14 +118,14 @@ pub fn read_only_module<T: CreateVTab>() -> &'static Module<T> {
xRollbackTo: None,
..ZERO_MODULE
},
phantom: PhantomData::<T>,
phantom: PhantomData::<&'vtab T>,
}
}
/// `feature = "vtab"` Create an eponymous only virtual table implementation.
///
/// Step 2 of [Creating New Virtual Table Implementations](https://sqlite.org/vtab.html#creating_new_virtual_table_implementations).
pub fn eponymous_only_module<T: VTab>() -> &'static Module<T> {
pub fn eponymous_only_module<'vtab, T: VTab<'vtab>>() -> &'static Module<'vtab, T> {
// A virtual table is eponymous if its xCreate method is the exact same function
// as the xConnect method For eponymous-only virtual tables, the xCreate
// method is NULL
@@ -157,7 +157,7 @@ pub fn eponymous_only_module<T: VTab>() -> &'static Module<T> {
xRollbackTo: None,
..ZERO_MODULE
},
phantom: PhantomData::<T>,
phantom: PhantomData::<&'vtab T>,
}
}
@@ -204,7 +204,7 @@ impl VTabConnection {
/// ```
///
/// (See [SQLite doc](https://sqlite.org/c3ref/vtab.html))
pub unsafe trait VTab: Sized {
pub unsafe trait VTab<'vtab>: Sized {
/// Client data passed to `Connection::create_module`.
type Aux;
/// Specific cursor implementation
@@ -225,13 +225,13 @@ pub unsafe trait VTab: Sized {
/// Create a new cursor used for accessing a virtual table.
/// (See [SQLite doc](https://sqlite.org/vtab.html#the_xopen_method))
fn open(&self) -> Result<Self::Cursor>;
fn open(&'vtab self) -> Result<Self::Cursor>;
}
/// `feature = "vtab"` Non-eponymous virtual table instance trait.
///
/// (See [SQLite doc](https://sqlite.org/c3ref/vtab.html))
pub trait CreateVTab: VTab {
pub trait CreateVTab<'vtab>: VTab<'vtab> {
/// 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
@@ -607,10 +607,10 @@ impl Connection {
///
/// Step 3 of [Creating New Virtual Table
/// Implementations](https://sqlite.org/vtab.html#creating_new_virtual_table_implementations).
pub fn create_module<T: VTab>(
pub fn create_module<'vtab, T: VTab<'vtab>>(
&self,
module_name: &str,
module: &'static Module<T>,
module: &'static Module<'vtab, T>,
aux: Option<T::Aux>,
) -> Result<()> {
self.db.borrow_mut().create_module(module_name, module, aux)
@@ -618,10 +618,10 @@ impl Connection {
}
impl InnerConnection {
fn create_module<T: VTab>(
fn create_module<'vtab, T: VTab<'vtab>>(
&mut self,
module_name: &str,
module: &'static Module<T>,
module: &'static Module<'vtab, T>,
aux: Option<T::Aux>,
) -> Result<()> {
let c_name = str_to_cstring(module_name)?;
@@ -703,7 +703,7 @@ unsafe extern "C" fn free_boxed_value<T>(p: *mut c_void) {
let _: Box<T> = Box::from_raw(p as *mut T);
}
unsafe extern "C" fn rust_create<T>(
unsafe extern "C" fn rust_create<'vtab, T>(
db: *mut ffi::sqlite3,
aux: *mut c_void,
argc: c_int,
@@ -712,7 +712,7 @@ unsafe extern "C" fn rust_create<T>(
err_msg: *mut *mut c_char,
) -> c_int
where
T: CreateVTab,
T: CreateVTab<'vtab>,
{
use std::ffi::CStr;
@@ -755,7 +755,7 @@ where
}
}
unsafe extern "C" fn rust_connect<T>(
unsafe extern "C" fn rust_connect<'vtab, T>(
db: *mut ffi::sqlite3,
aux: *mut c_void,
argc: c_int,
@@ -764,7 +764,7 @@ unsafe extern "C" fn rust_connect<T>(
err_msg: *mut *mut c_char,
) -> c_int
where
T: VTab,
T: VTab<'vtab>,
{
use std::ffi::CStr;
@@ -807,12 +807,12 @@ where
}
}
unsafe extern "C" fn rust_best_index<T>(
unsafe extern "C" fn rust_best_index<'vtab, T>(
vtab: *mut ffi::sqlite3_vtab,
info: *mut ffi::sqlite3_index_info,
) -> c_int
where
T: VTab,
T: VTab<'vtab>,
{
let vt = vtab as *mut T;
let mut idx_info = IndexInfo(info);
@@ -831,9 +831,9 @@ where
}
}
unsafe extern "C" fn rust_disconnect<T>(vtab: *mut ffi::sqlite3_vtab) -> c_int
unsafe extern "C" fn rust_disconnect<'vtab, T>(vtab: *mut ffi::sqlite3_vtab) -> c_int
where
T: VTab,
T: VTab<'vtab>,
{
if vtab.is_null() {
return ffi::SQLITE_OK;
@@ -843,9 +843,9 @@ where
ffi::SQLITE_OK
}
unsafe extern "C" fn rust_destroy<T>(vtab: *mut ffi::sqlite3_vtab) -> c_int
unsafe extern "C" fn rust_destroy<'vtab, T>(vtab: *mut ffi::sqlite3_vtab) -> c_int
where
T: CreateVTab,
T: CreateVTab<'vtab>,
{
if vtab.is_null() {
return ffi::SQLITE_OK;
@@ -869,12 +869,12 @@ where
}
}
unsafe extern "C" fn rust_open<T>(
unsafe extern "C" fn rust_open<'vtab, T: 'vtab>(
vtab: *mut ffi::sqlite3_vtab,
pp_cursor: *mut *mut ffi::sqlite3_vtab_cursor,
) -> c_int
where
T: VTab,
T: VTab<'vtab>,
{
let vt = vtab as *mut T;
match (*vt).open() {