Module rusqlite::functions [−][src]
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.
extern crate libsqlite3_sys; extern crate rusqlite; extern crate regex; use regex::Regex; use rusqlite::{Connection, Error, Result}; 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 = try!(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 = try!(ctx.get::<String>(1)); Ok(regex.is_match(&text)) }) } fn main() { let db = Connection::open_in_memory().unwrap(); add_regexp_function(&db).unwrap(); let is_match: bool = db .query_row("SELECT regexp('[aeiou]*', 'aaaaeeeiii')", &[], |row| { row.get(0) }).unwrap(); assert!(is_match); }
Structs
Context |
Context is a wrapper for the SQLite function evaluation context. |
Traits
Aggregate |
Aggregate is the callback interface for user-defined aggregate function. |