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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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17
src/vtab/array.rs
View File

@ -27,6 +27,7 @@
//! ```
use std::default::Default;
use std::marker::PhantomData;
use std::os::raw::{c_char, c_int, c_void};
use std::rc::Rc;
@ -72,9 +73,9 @@ struct ArrayTab {
base: ffi::sqlite3_vtab,
}
unsafe impl VTab for ArrayTab {
unsafe impl<'vtab> VTab<'vtab> for ArrayTab {
type Aux = ();
type Cursor = ArrayTabCursor;
type Cursor = ArrayTabCursor<'vtab>;
fn connect(
_: &mut VTabConnection,
@ -118,28 +119,30 @@ unsafe impl VTab for ArrayTab {
Ok(())
}
fn open(&self) -> Result<ArrayTabCursor> {
fn open(&'vtab self) -> Result<ArrayTabCursor<'vtab>> {
Ok(ArrayTabCursor::new())
}
}
/// A cursor for the Array virtual table
#[repr(C)]
struct ArrayTabCursor {
struct ArrayTabCursor<'vtab> {
/// Base class. Must be first
base: ffi::sqlite3_vtab_cursor,
/// The rowid
row_id: i64,
/// Pointer to the array of values ("pointer")
ptr: Option<Array>,
phantom: PhantomData<&'vtab ArrayTab>,
}
impl ArrayTabCursor {
fn new() -> ArrayTabCursor {
impl ArrayTabCursor<'_> {
fn new<'vtab>() -> ArrayTabCursor<'vtab> {
ArrayTabCursor {
base: ffi::sqlite3_vtab_cursor::default(),
row_id: 0,
ptr: None,
phantom: PhantomData,
}
}
@ -150,7 +153,7 @@ impl ArrayTabCursor {
}
}
}
unsafe impl VTabCursor for ArrayTabCursor {
unsafe impl VTabCursor for ArrayTabCursor<'_> {
fn filter(&mut self, idx_num: c_int, _idx_str: Option<&str>, args: &Values<'_>) -> Result<()> {
if idx_num > 0 {
self.ptr = args.get_array(0)?;

19
src/vtab/csvtab.rs
View File

@ -22,6 +22,7 @@
//! }
//! ```
use std::fs::File;
use std::marker::PhantomData;
use std::os::raw::c_int;
use std::path::Path;
use std::str;
@ -95,9 +96,9 @@ impl CSVTab {
}
}
unsafe impl VTab for CSVTab {
unsafe impl<'vtab> VTab<'vtab> for CSVTab {
type Aux = ();
type Cursor = CSVTabCursor;
type Cursor = CSVTabCursor<'vtab>;
fn connect(
_: &mut VTabConnection,
@ -258,16 +259,16 @@ unsafe impl VTab for CSVTab {
Ok(())
}
fn open(&self) -> Result<CSVTabCursor> {
fn open(&'vtab self) -> Result<CSVTabCursor<'vtab>> {
Ok(CSVTabCursor::new(self.reader()?))
}
}
impl CreateVTab for CSVTab {}
impl CreateVTab<'_> for CSVTab {}
/// A cursor for the CSV virtual table
#[repr(C)]
struct CSVTabCursor {
struct CSVTabCursor<'vtab> {
/// Base class. Must be first
base: ffi::sqlite3_vtab_cursor,
/// The CSV reader object
@ -277,16 +278,18 @@ struct CSVTabCursor {
/// Values of the current row
cols: csv::StringRecord,
eof: bool,
phantom: PhantomData<&'vtab CSVTab>,
}
impl CSVTabCursor {
fn new(reader: csv::Reader<File>) -> CSVTabCursor {
impl CSVTabCursor<'_> {
fn new<'vtab>(reader: csv::Reader<File>) -> CSVTabCursor<'vtab> {
CSVTabCursor {
base: ffi::sqlite3_vtab_cursor::default(),
reader,
row_number: 0,
cols: csv::StringRecord::new(),
eof: false,
phantom: PhantomData,
}
}
@ -296,7 +299,7 @@ impl CSVTabCursor {
}
}
unsafe impl VTabCursor for CSVTabCursor {
unsafe impl VTabCursor for CSVTabCursor<'_> {
// Only a full table scan is supported. So `filter` simply rewinds to
// the beginning.
fn filter(

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() {

28
src/vtab/series.rs
View File

@ -4,6 +4,7 @@
//! "function"](http://www.sqlite.org/cgi/src/finfo?name=ext/misc/series.c):
//! https://www.sqlite.org/series.html
use std::default::Default;
use std::marker::PhantomData;
use std::os::raw::c_int;
use crate::ffi;
@ -49,9 +50,9 @@ struct SeriesTab {
base: ffi::sqlite3_vtab,
}
unsafe impl VTab for SeriesTab {
unsafe impl<'vtab> VTab<'vtab> for SeriesTab {
type Aux = ();
type Cursor = SeriesTabCursor;
type Cursor = SeriesTabCursor<'vtab>;
fn connect(
_: &mut VTabConnection,
@ -151,15 +152,14 @@ unsafe impl VTab for SeriesTab {
Ok(())
}
fn open(&self) -> Result<SeriesTabCursor> {
fn open(&'vtab self) -> Result<SeriesTabCursor<'vtab>> {
Ok(SeriesTabCursor::new())
}
}
/// A cursor for the Series virtual table
#[derive(Default)]
#[repr(C)]
struct SeriesTabCursor {
struct SeriesTabCursor<'vtab> {
/// Base class. Must be first
base: ffi::sqlite3_vtab_cursor,
/// True to count down rather than up
@ -174,14 +174,24 @@ struct SeriesTabCursor {
max_value: i64,
/// Increment ("step")
step: i64,
phantom: PhantomData<&'vtab SeriesTab>,
}
impl SeriesTabCursor {
fn new() -> SeriesTabCursor {
SeriesTabCursor::default()
impl SeriesTabCursor<'_> {
fn new<'vtab>() -> SeriesTabCursor<'vtab> {
SeriesTabCursor {
base: ffi::sqlite3_vtab_cursor::default(),
is_desc: false,
row_id: 0,
value: 0,
min_value: 0,
max_value: 0,
step: 0,
phantom: PhantomData,
}
}
unsafe impl VTabCursor for SeriesTabCursor {
}
unsafe impl VTabCursor for SeriesTabCursor<'_> {
fn filter(&mut self, idx_num: c_int, _idx_str: Option<&str>, args: &Values<'_>) -> Result<()> {
let idx_num = QueryPlanFlags::from_bits_truncate(idx_num);
let mut i = 0;

12
tests/vtab.rs
View File

@ -9,6 +9,7 @@ fn test_dummy_module() {
VTabConnection, VTabCursor, Values,
};
use rusqlite::{version_number, Connection, Result};
use std::marker::PhantomData;
use std::os::raw::c_int;
let module = eponymous_only_module::<DummyTab>();
@ -19,9 +20,9 @@ fn test_dummy_module() {
base: sqlite3_vtab,
}
unsafe impl VTab for DummyTab {
unsafe impl<'vtab> VTab<'vtab> for DummyTab {
type Aux = ();
type Cursor = DummyTabCursor;
type Cursor = DummyTabCursor<'vtab>;
fn connect(
_: &mut VTabConnection,
@ -39,21 +40,22 @@ fn test_dummy_module() {
Ok(())
}
fn open(&self) -> Result<DummyTabCursor> {
fn open(&'vtab self) -> Result<DummyTabCursor<'vtab>> {
Ok(DummyTabCursor::default())
}
}
#[derive(Default)]
#[repr(C)]
struct DummyTabCursor {
struct DummyTabCursor<'vtab> {
/// Base class. Must be first
base: sqlite3_vtab_cursor,
/// The rowid
row_id: i64,
phantom: PhantomData<&'vtab DummyTab>,
}
unsafe impl VTabCursor for DummyTabCursor {
unsafe impl VTabCursor for DummyTabCursor<'_> {
fn filter(
&mut self,
_idx_num: c_int,