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use std::default::Default;
use std::marker::PhantomData;
use std::os::raw::c_int;
use std::str::FromStr;
use std::sync::atomic::{AtomicUsize, Ordering};
use crate::vtab::{
update_module, Context, CreateVTab, IndexInfo, UpdateVTab, VTab, VTabConnection, VTabCursor,
VTabKind, Values,
};
use crate::{ffi, ValueRef};
use crate::{Connection, Error, Result};
/// Register the "vtablog" module.
pub fn load_module(conn: &Connection) -> Result<()> {
let aux: Option<()> = None;
conn.create_module("vtablog", update_module::<VTabLog>(), aux)
}
/// An instance of the vtablog virtual table
#[repr(C)]
struct VTabLog {
/// Base class. Must be first
base: ffi::sqlite3_vtab,
/// Number of rows in the table
n_row: i64,
/// Instance number for this vtablog table
i_inst: usize,
/// Number of cursors created
n_cursor: usize,
}
impl VTabLog {
fn connect_create(
_: &mut VTabConnection,
_: Option<&()>,
args: &[&[u8]],
is_create: bool,
) -> Result<(String, VTabLog)> {
static N_INST: AtomicUsize = AtomicUsize::new(1);
let i_inst = N_INST.fetch_add(1, Ordering::SeqCst);
println!(
"VTabLog::{}(tab={}, args={:?}):",
if is_create { "create" } else { "connect" },
i_inst,
args,
);
let mut schema = None;
let mut n_row = None;
let args = &args[3..];
for c_slice in args {
let (param, value) = super::parameter(c_slice)?;
match param {
"schema" => {
if schema.is_some() {
return Err(Error::ModuleError(format!(
"more than one '{param}' parameter"
)));
}
schema = Some(value.to_owned())
}
"rows" => {
if n_row.is_some() {
return Err(Error::ModuleError(format!(
"more than one '{param}' parameter"
)));
}
if let Ok(n) = i64::from_str(value) {
n_row = Some(n)
}
}
_ => {
return Err(Error::ModuleError(format!(
"unrecognized parameter '{param}'"
)));
}
}
}
if schema.is_none() {
return Err(Error::ModuleError("no schema defined".to_owned()));
}
let vtab = VTabLog {
base: ffi::sqlite3_vtab::default(),
n_row: n_row.unwrap_or(10),
i_inst,
n_cursor: 0,
};
Ok((schema.unwrap(), vtab))
}
}
impl Drop for VTabLog {
fn drop(&mut self) {
println!("VTabLog::drop({})", self.i_inst);
}
}
unsafe impl<'vtab> VTab<'vtab> for VTabLog {
type Aux = ();
type Cursor = VTabLogCursor<'vtab>;
fn connect(
db: &mut VTabConnection,
aux: Option<&Self::Aux>,
args: &[&[u8]],
) -> Result<(String, Self)> {
VTabLog::connect_create(db, aux, args, false)
}
fn best_index(&self, info: &mut IndexInfo) -> Result<()> {
println!("VTabLog::best_index({})", self.i_inst);
info.set_estimated_cost(500.);
info.set_estimated_rows(500);
Ok(())
}
fn open(&'vtab mut self) -> Result<Self::Cursor> {
self.n_cursor += 1;
println!(
"VTabLog::open(tab={}, cursor={})",
self.i_inst, self.n_cursor
);
Ok(VTabLogCursor {
base: ffi::sqlite3_vtab_cursor::default(),
i_cursor: self.n_cursor,
row_id: 0,
phantom: PhantomData,
})
}
}
impl<'vtab> CreateVTab<'vtab> for VTabLog {
const KIND: VTabKind = VTabKind::Default;
fn create(
db: &mut VTabConnection,
aux: Option<&Self::Aux>,
args: &[&[u8]],
) -> Result<(String, Self)> {
VTabLog::connect_create(db, aux, args, true)
}
fn destroy(&self) -> Result<()> {
println!("VTabLog::destroy({})", self.i_inst);
Ok(())
}
}
impl<'vtab> UpdateVTab<'vtab> for VTabLog {
fn delete(&mut self, arg: ValueRef<'_>) -> Result<()> {
println!("VTabLog::delete({}, {arg:?})", self.i_inst);
Ok(())
}
fn insert(&mut self, args: &Values<'_>) -> Result<i64> {
println!(
"VTabLog::insert({}, {:?})",
self.i_inst,
args.iter().collect::<Vec<ValueRef<'_>>>()
);
Ok(self.n_row)
}
fn update(&mut self, args: &Values<'_>) -> Result<()> {
println!(
"VTabLog::update({}, {:?})",
self.i_inst,
args.iter().collect::<Vec<ValueRef<'_>>>()
);
Ok(())
}
}
/// A cursor for the Series virtual table
#[repr(C)]
struct VTabLogCursor<'vtab> {
/// Base class. Must be first
base: ffi::sqlite3_vtab_cursor,
/// Cursor number
i_cursor: usize,
/// The rowid
row_id: i64,
phantom: PhantomData<&'vtab VTabLog>,
}
impl VTabLogCursor<'_> {
fn vtab(&self) -> &VTabLog {
unsafe { &*(self.base.pVtab as *const VTabLog) }
}
}
impl Drop for VTabLogCursor<'_> {
fn drop(&mut self) {
println!(
"VTabLogCursor::drop(tab={}, cursor={})",
self.vtab().i_inst,
self.i_cursor
);
}
}
unsafe impl VTabCursor for VTabLogCursor<'_> {
fn filter(&mut self, _: c_int, _: Option<&str>, _: &Values<'_>) -> Result<()> {
println!(
"VTabLogCursor::filter(tab={}, cursor={})",
self.vtab().i_inst,
self.i_cursor
);
self.row_id = 0;
Ok(())
}
fn next(&mut self) -> Result<()> {
println!(
"VTabLogCursor::next(tab={}, cursor={}): rowid {} -> {}",
self.vtab().i_inst,
self.i_cursor,
self.row_id,
self.row_id + 1
);
self.row_id += 1;
Ok(())
}
fn eof(&self) -> bool {
let eof = self.row_id >= self.vtab().n_row;
println!(
"VTabLogCursor::eof(tab={}, cursor={}): {}",
self.vtab().i_inst,
self.i_cursor,
eof,
);
eof
}
fn column(&self, ctx: &mut Context, i: c_int) -> Result<()> {
let value = if i < 26 {
format!(
"{}{}",
"abcdefghijklmnopqrstuvwyz".chars().nth(i as usize).unwrap(),
self.row_id
)
} else {
format!("{i}{}", self.row_id)
};
println!(
"VTabLogCursor::column(tab={}, cursor={}, i={}): {}",
self.vtab().i_inst,
self.i_cursor,
i,
value,
);
ctx.set_result(&value)
}
fn rowid(&self) -> Result<i64> {
println!(
"VTabLogCursor::rowid(tab={}, cursor={}): {}",
self.vtab().i_inst,
self.i_cursor,
self.row_id,
);
Ok(self.row_id)
}
}
#[cfg(test)]
mod test {
use crate::{Connection, Result};
#[test]
fn test_module() -> Result<()> {
let db = Connection::open_in_memory()?;
super::load_module(&db)?;
db.execute_batch(
"CREATE VIRTUAL TABLE temp.log USING vtablog(
schema='CREATE TABLE x(a,b,c)',
rows=25
);",
)?;
let mut stmt = db.prepare("SELECT * FROM log;")?;
let mut rows = stmt.query([])?;
while rows.next()?.is_some() {}
db.execute("DELETE FROM log WHERE a = ?1", ["a1"])?;
db.execute(
"INSERT INTO log (a, b, c) VALUES (?1, ?2, ?3)",
["a", "b", "c"],
)?;
db.execute(
"UPDATE log SET b = ?1, c = ?2 WHERE a = ?3",
["bn", "cn", "a1"],
)?;
Ok(())
}
}