[−][src]Module c3p0_pool_sqlite::rusqlite::functions
Create or redefine SQL functions.
Example
Adding a regexp
function to a connection in which compiled regular
expressions are cached in a HashMap
. For an alternative implementation
that uses SQLite's Function Auxilliary Data interface
to avoid recompiling regular expressions, see the unit tests for this
module.
use regex::Regex; use rusqlite::{Connection, Error, Result, NO_PARAMS}; use std::collections::HashMap; fn add_regexp_function(db: &Connection) -> Result<()> { let mut cached_regexes = HashMap::new(); db.create_scalar_function("regexp", 2, true, move |ctx| { let regex_s = ctx.get::<String>(0)?; let entry = cached_regexes.entry(regex_s.clone()); let regex = { use std::collections::hash_map::Entry::{Occupied, Vacant}; match entry { Occupied(occ) => occ.into_mut(), Vacant(vac) => match Regex::new(®ex_s) { Ok(r) => vac.insert(r), Err(err) => return Err(Error::UserFunctionError(Box::new(err))), }, } }; let text = ctx.get::<String>(1)?; Ok(regex.is_match(&text)) }) } fn main() -> Result<()> { let db = Connection::open_in_memory()?; add_regexp_function(&db)?; let is_match: bool = db.query_row( "SELECT regexp('[aeiou]*', 'aaaaeeeiii')", NO_PARAMS, |row| row.get(0), )?; assert!(is_match); Ok(()) }
Structs
Context | Context is a wrapper for the SQLite function evaluation context. |
Traits
Aggregate | Aggregate is the callback interface for user-defined aggregate function. |