Merge pull request #95 from jgallagher/gwenn-functions

Add support for user-defined functions

.travis.yml

@@ -11,8 +11,9 @@ script:
     - cargo test --features backup
     - cargo test --features load_extension
     - cargo test --features trace
-    - cargo test --features "backup load_extension trace"
+    - cargo test --features functions
-    - cargo doc --no-deps --features "backup load_extension trace"
+    - cargo test --features "backup functions load_extension trace"
+    - cargo doc --no-deps --features "backup functions load_extension trace"
 
 after_success: |
     [ $TRAVIS_BRANCH = master ] &&

Cargo.toml

@@ -15,6 +15,7 @@ name = "rusqlite"
 [features]
 load_extension = ["libsqlite3-sys/load_extension"]
 backup = []
+functions = []
 trace = []
 
 [dependencies]
@@ -25,6 +26,7 @@ libc = "~0.2"
 [dev-dependencies]
 tempdir = "~0.3.4"
 lazy_static = "~0.1"
+regex = "~0.1.41"
 
 [dependencies.libsqlite3-sys]
 path = "libsqlite3-sys"

Changelog.md

@@ -1,7 +1,9 @@
 # Version UPCOMING (TBD)
 
-* Adds `backup` feature that exposes SQLite's online backup API.
 * Adds a variety of `..._named` methods for executing queries using named placeholder parameters.
+* Adds `backup` feature that exposes SQLite's online backup API.
+* Adds `functions` feature that allows user-defined scalar functions to be added to
+  open `SqliteConnection`s.
 
 # Version 0.5.0 (2015-12-08)
 

libsqlite3-sys/src/lib.rs

@@ -94,3 +94,5 @@ pub fn code_to_str(code: c_int) -> &'static str {
 }
 
 pub const SQLITE_CONFIG_LOG  : c_int = 16;
+pub const SQLITE_UTF8  : c_int = 1;
+pub const SQLITE_DETERMINISTIC  : c_int = 0x800;

src/functions.rs

@@ -0,0 +1,644 @@
+//! 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](https://www.sqlite.org/c3ref/get_auxdata.html) interface
+//! to avoid recompiling regular expressions, see the unit tests for this module.
+//!
+//! ```rust
+//! extern crate libsqlite3_sys;
+//! extern crate rusqlite;
+//! extern crate regex;
+//!
+//! use rusqlite::{SqliteConnection, SqliteError, SqliteResult};
+//! use std::collections::HashMap;
+//! use regex::Regex;
+//!
+//! fn add_regexp_function(db: &SqliteConnection) -> SqliteResult<()> {
+//!     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) => {
+//!                     let r = try!(Regex::new(&regex_s).map_err(|e| SqliteError {
+//!                         code: libsqlite3_sys::SQLITE_ERROR,
+//!                         message: format!("Invalid regular expression: {}", e),
+//!                     }));
+//!                     vac.insert(r)
+//!                 }
+//!             }
+//!         };
+//!
+//!         let text = try!(ctx.get::<String>(1));
+//!         Ok(regex.is_match(&text))
+//!     })
+//! }
+//!
+//! fn main() {
+//!     let db = SqliteConnection::open_in_memory().unwrap();
+//!     add_regexp_function(&db).unwrap();
+//!
+//!     let is_match = db.query_row("SELECT regexp('[aeiou]*', 'aaaaeeeiii')", &[],
+//!                                 |row| row.get::<bool>(0)).unwrap();
+//!
+//!     assert!(is_match);
+//! }
+//! ```
+use std::ffi::CStr;
+use std::mem;
+use std::ptr;
+use std::slice;
+use std::str;
+use libc::{c_int, c_double, c_char, c_void};
+
+use ffi;
+pub use ffi::sqlite3_context;
+pub use ffi::sqlite3_value;
+pub use ffi::sqlite3_value_type;
+pub use ffi::sqlite3_value_numeric_type;
+
+use types::Null;
+
+use {SqliteResult, SqliteError, SqliteConnection, str_to_cstring, InnerSqliteConnection};
+
+/// A trait for types that can be converted into the result of an SQL function.
+pub trait ToResult {
+    unsafe fn set_result(&self, ctx: *mut sqlite3_context);
+}
+
+macro_rules! raw_to_impl(
+    ($t:ty, $f:ident) => (
+        impl ToResult for $t {
+            unsafe fn set_result(&self, ctx: *mut sqlite3_context) {
+                ffi::$f(ctx, *self)
+            }
+        }
+    )
+);
+
+raw_to_impl!(c_int, sqlite3_result_int);
+raw_to_impl!(i64, sqlite3_result_int64);
+raw_to_impl!(c_double, sqlite3_result_double);
+
+impl<'a> ToResult for bool {
+    unsafe fn set_result(&self, ctx: *mut sqlite3_context) {
+        match *self {
+            true => ffi::sqlite3_result_int(ctx, 1),
+            _ => ffi::sqlite3_result_int(ctx, 0),
+        }
+    }
+}
+
+
+impl<'a> ToResult for &'a str {
+    unsafe fn set_result(&self, ctx: *mut sqlite3_context) {
+        let length = self.len();
+        if length > ::std::i32::MAX as usize {
+            ffi::sqlite3_result_error_toobig(ctx);
+            return;
+        }
+        match str_to_cstring(self) {
+            Ok(c_str) => {
+                ffi::sqlite3_result_text(ctx,
+                                         c_str.as_ptr(),
+                                         length as c_int,
+                                         ffi::SQLITE_TRANSIENT())
+            }
+            Err(_) => ffi::sqlite3_result_error_code(ctx, ffi::SQLITE_MISUSE), // TODO sqlite3_result_error
+        }
+    }
+}
+
+impl ToResult for String {
+    unsafe fn set_result(&self, ctx: *mut sqlite3_context) {
+        (&self[..]).set_result(ctx)
+    }
+}
+
+impl<'a> ToResult for &'a [u8] {
+    unsafe fn set_result(&self, ctx: *mut sqlite3_context) {
+        if self.len() > ::std::i32::MAX as usize {
+            ffi::sqlite3_result_error_toobig(ctx);
+            return;
+        }
+        ffi::sqlite3_result_blob(ctx,
+                                 mem::transmute(self.as_ptr()),
+                                 self.len() as c_int,
+                                 ffi::SQLITE_TRANSIENT())
+    }
+}
+
+impl ToResult for Vec<u8> {
+    unsafe fn set_result(&self, ctx: *mut sqlite3_context) {
+        (&self[..]).set_result(ctx)
+    }
+}
+
+impl<T: ToResult> ToResult for Option<T> {
+    unsafe fn set_result(&self, ctx: *mut sqlite3_context) {
+        match *self {
+            None => ffi::sqlite3_result_null(ctx),
+            Some(ref t) => t.set_result(ctx),
+        }
+    }
+}
+
+impl ToResult for Null {
+    unsafe fn set_result(&self, ctx: *mut sqlite3_context) {
+        ffi::sqlite3_result_null(ctx)
+    }
+}
+
+
+// sqlite3_result_error_code, c_int
+// sqlite3_result_error_nomem
+// sqlite3_result_error_toobig
+// sqlite3_result_error, *const c_char, c_int
+// sqlite3_result_zeroblob
+// sqlite3_result_value
+
+/// A trait for types that can be created from a SQLite function parameter value.
+pub trait FromValue: Sized {
+    unsafe fn parameter_value(v: *mut sqlite3_value) -> SqliteResult<Self>;
+
+    /// FromValue types can implement this method and use sqlite3_value_type to check that
+    /// the type reported by SQLite matches a type suitable for Self. This method is used
+    /// by `Context::get` to confirm that the parameter contains a valid type before
+    /// attempting to retrieve the value.
+    unsafe fn parameter_has_valid_sqlite_type(_: *mut sqlite3_value) -> bool {
+        true
+    }
+}
+
+
+macro_rules! raw_from_impl(
+    ($t:ty, $f:ident, $c:expr) => (
+        impl FromValue for $t {
+            unsafe fn parameter_value(v: *mut sqlite3_value) -> SqliteResult<$t> {
+                Ok(ffi::$f(v))
+            }
+
+            unsafe fn parameter_has_valid_sqlite_type(v: *mut sqlite3_value) -> bool {
+                sqlite3_value_numeric_type(v) == $c
+            }
+        }
+    )
+);
+
+raw_from_impl!(c_int, sqlite3_value_int, ffi::SQLITE_INTEGER);
+raw_from_impl!(i64, sqlite3_value_int64, ffi::SQLITE_INTEGER);
+
+impl FromValue for bool {
+    unsafe fn parameter_value(v: *mut sqlite3_value) -> SqliteResult<bool> {
+        match ffi::sqlite3_value_int(v) {
+            0 => Ok(false),
+            _ => Ok(true),
+        }
+    }
+
+    unsafe fn parameter_has_valid_sqlite_type(v: *mut sqlite3_value) -> bool {
+        sqlite3_value_numeric_type(v) == ffi::SQLITE_INTEGER
+    }
+}
+
+impl FromValue for c_double {
+    unsafe fn parameter_value(v: *mut sqlite3_value) -> SqliteResult<c_double> {
+        Ok(ffi::sqlite3_value_double(v))
+    }
+
+    unsafe fn parameter_has_valid_sqlite_type(v: *mut sqlite3_value) -> bool {
+        sqlite3_value_numeric_type(v) == ffi::SQLITE_FLOAT ||
+        sqlite3_value_numeric_type(v) == ffi::SQLITE_INTEGER
+    }
+}
+
+impl FromValue for String {
+    unsafe fn parameter_value(v: *mut sqlite3_value) -> SqliteResult<String> {
+        let c_text = ffi::sqlite3_value_text(v);
+        if c_text.is_null() {
+            Ok("".to_string())
+        } else {
+            let c_slice = CStr::from_ptr(c_text as *const c_char).to_bytes();
+            let utf8_str = str::from_utf8(c_slice);
+            utf8_str.map(|s| s.to_string())
+                    .map_err(|e| {
+                        SqliteError {
+                            code: 0,
+                            message: e.to_string(),
+                        }
+                    })
+        }
+    }
+
+    unsafe fn parameter_has_valid_sqlite_type(v: *mut sqlite3_value) -> bool {
+        sqlite3_value_type(v) == ffi::SQLITE_TEXT
+    }
+}
+
+impl FromValue for Vec<u8> {
+    unsafe fn parameter_value(v: *mut sqlite3_value) -> SqliteResult<Vec<u8>> {
+        use std::slice::from_raw_parts;
+        let c_blob = ffi::sqlite3_value_blob(v);
+        let len = ffi::sqlite3_value_bytes(v);
+
+        assert!(len >= 0,
+                "unexpected negative return from sqlite3_value_bytes");
+        let len = len as usize;
+
+        Ok(from_raw_parts(mem::transmute(c_blob), len).to_vec())
+    }
+
+    unsafe fn parameter_has_valid_sqlite_type(v: *mut sqlite3_value) -> bool {
+        sqlite3_value_type(v) == ffi::SQLITE_BLOB
+    }
+}
+
+impl<T: FromValue> FromValue for Option<T> {
+    unsafe fn parameter_value(v: *mut sqlite3_value) -> SqliteResult<Option<T>> {
+        if sqlite3_value_type(v) == ffi::SQLITE_NULL {
+            Ok(None)
+        } else {
+            FromValue::parameter_value(v).map(|t| Some(t))
+        }
+    }
+
+    unsafe fn parameter_has_valid_sqlite_type(v: *mut sqlite3_value) -> bool {
+        sqlite3_value_type(v) == ffi::SQLITE_NULL || T::parameter_has_valid_sqlite_type(v)
+    }
+}
+
+unsafe extern "C" fn free_boxed_value<T>(p: *mut c_void) {
+    let _: Box<T> = Box::from_raw(mem::transmute(p));
+}
+
+/// Context is a wrapper for the SQLite function evaluation context.
+pub struct Context<'a> {
+    ctx: *mut sqlite3_context,
+    args: &'a [*mut sqlite3_value],
+}
+
+impl<'a> Context<'a> {
+    /// Returns the number of arguments to the function.
+    pub fn len(&self) -> usize {
+        self.args.len()
+    }
+
+    /// Returns the `idx`th argument as a `T`.
+    ///
+    /// # Failure
+    ///
+    /// Will panic if `idx` is greater than or equal to `self.len()`.
+    ///
+    /// Will return Err if the underlying SQLite type cannot be converted to a `T`.
+    pub fn get<T: FromValue>(&self, idx: usize) -> SqliteResult<T> {
+        let arg = self.args[idx];
+        unsafe {
+            if T::parameter_has_valid_sqlite_type(arg) {
+                T::parameter_value(arg)
+            } else {
+                Err(SqliteError {
+                    code: ffi::SQLITE_MISMATCH,
+                    message: "Invalid value type".to_string(),
+                })
+            }
+        }
+    }
+
+    /// Sets the auxilliary data associated with a particular parameter. See
+    /// https://www.sqlite.org/c3ref/get_auxdata.html for a discussion of
+    /// this feature, or the unit tests of this module for an example.
+    pub fn set_aux<T>(&self, arg: c_int, value: T) {
+        let boxed = Box::into_raw(Box::new(value));
+        unsafe {
+            ffi::sqlite3_set_auxdata(self.ctx,
+                                     arg,
+                                     mem::transmute(boxed),
+                                     Some(mem::transmute(free_boxed_value::<T>)))
+        };
+    }
+
+    /// Gets the auxilliary data that was associated with a given parameter
+    /// via `set_aux`. Returns `None` if no data has been associated.
+    ///
+    /// # Unsafety
+    ///
+    /// This function is unsafe as there is no guarantee that the type `T`
+    /// requested matches the type `T` that was provided to `set_aux`. The
+    /// types must be identical.
+    pub unsafe fn get_aux<T>(&self, arg: c_int) -> Option<&T> {
+        let p = ffi::sqlite3_get_auxdata(self.ctx, arg) as *mut T;
+        if p.is_null() {
+            None
+        } else {
+            Some(&*p)
+        }
+    }
+}
+
+impl SqliteConnection {
+    /// Attach a user-defined scalar function to this database connection.
+    ///
+    /// `fn_name` is the name the function will be accessible from SQL.
+    /// `n_arg` is the number of arguments to the function. Use `-1` for a variable
+    /// number. If the function always returns the same value given the same
+    /// input, `deterministic` should be `true`.
+    ///
+    /// The function will remain available until the connection is closed or
+    /// until it is explicitly removed via `remove_function`.
+    ///
+    /// # Example
+    ///
+    /// ```rust
+    /// # use rusqlite::{SqliteConnection, SqliteResult};
+    /// # type c_double = f64;
+    /// fn scalar_function_example(db: SqliteConnection) -> SqliteResult<()> {
+    ///     try!(db.create_scalar_function("halve", 1, true, |ctx| {
+    ///         let value = try!(ctx.get::<c_double>(0));
+    ///         Ok(value / 2f64)
+    ///     }));
+    ///
+    ///     let six_halved = try!(db.query_row("SELECT halve(6)", &[], |r| r.get::<f64>(0)));
+    ///     assert_eq!(six_halved, 3f64);
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
+    /// # Failure
+    ///
+    /// Will return Err if the function could not be attached to the connection.
+    pub fn create_scalar_function<F, T>(&self,
+                                        fn_name: &str,
+                                        n_arg: c_int,
+                                        deterministic: bool,
+                                        x_func: F)
+                                        -> SqliteResult<()>
+        where F: FnMut(&Context) -> SqliteResult<T>,
+              T: ToResult
+    {
+        self.db.borrow_mut().create_scalar_function(fn_name, n_arg, deterministic, x_func)
+    }
+
+    /// Removes a user-defined function from this database connection.
+    ///
+    /// `fn_name` and `n_arg` should match the name and number of arguments
+    /// given to `create_scalar_function`.
+    ///
+    /// # Failure
+    ///
+    /// Will return Err if the function could not be removed.
+    pub fn remove_function(&self, fn_name: &str, n_arg: c_int) -> SqliteResult<()> {
+        self.db.borrow_mut().remove_function(fn_name, n_arg)
+    }
+}
+
+impl InnerSqliteConnection {
+    fn create_scalar_function<F, T>(&mut self,
+                                    fn_name: &str,
+                                    n_arg: c_int,
+                                    deterministic: bool,
+                                    x_func: F)
+                                    -> SqliteResult<()>
+        where F: FnMut(&Context) -> SqliteResult<T>,
+              T: ToResult
+    {
+        extern "C" fn call_boxed_closure<F, T>(ctx: *mut sqlite3_context,
+                                               argc: c_int,
+                                               argv: *mut *mut sqlite3_value)
+            where F: FnMut(&Context) -> SqliteResult<T>,
+                  T: ToResult
+        {
+            unsafe {
+                let ctx = Context {
+                    ctx: ctx,
+                    args: slice::from_raw_parts(argv, argc as usize),
+                };
+                let boxed_f: *mut F = mem::transmute(ffi::sqlite3_user_data(ctx.ctx));
+                assert!(!boxed_f.is_null(), "Internal error - null function pointer");
+                match (*boxed_f)(&ctx) {
+                    Ok(r) => r.set_result(ctx.ctx),
+                    Err(e) => {
+                        ffi::sqlite3_result_error_code(ctx.ctx, e.code);
+                        if let Ok(cstr) = str_to_cstring(&e.message) {
+                            ffi::sqlite3_result_error(ctx.ctx, cstr.as_ptr(), -1);
+                        }
+                    }
+                }
+            }
+        }
+
+        let boxed_f: *mut F = Box::into_raw(Box::new(x_func));
+        let c_name = try!(str_to_cstring(fn_name));
+        let mut flags = ffi::SQLITE_UTF8;
+        if deterministic {
+            flags |= ffi::SQLITE_DETERMINISTIC;
+        }
+        let r = unsafe {
+            ffi::sqlite3_create_function_v2(self.db(),
+                                            c_name.as_ptr(),
+                                            n_arg,
+                                            flags,
+                                            mem::transmute(boxed_f),
+                                            Some(call_boxed_closure::<F, T>),
+                                            None,
+                                            None,
+                                            Some(mem::transmute(free_boxed_value::<F>)))
+        };
+        self.decode_result(r)
+    }
+
+    fn remove_function(&mut self, fn_name: &str, n_arg: c_int) -> SqliteResult<()> {
+        let c_name = try!(str_to_cstring(fn_name));
+        let r = unsafe {
+            ffi::sqlite3_create_function_v2(self.db(),
+                                            c_name.as_ptr(),
+                                            n_arg,
+                                            ffi::SQLITE_UTF8,
+                                            ptr::null_mut(),
+                                            None,
+                                            None,
+                                            None,
+                                            None)
+        };
+        self.decode_result(r)
+    }
+}
+
+#[cfg(test)]
+mod test {
+    extern crate regex;
+
+    use std::collections::HashMap;
+    use libc::c_double;
+    use self::regex::Regex;
+
+    use {SqliteConnection, SqliteError, SqliteResult};
+    use ffi;
+    use functions::Context;
+
+    fn half(ctx: &Context) -> SqliteResult<c_double> {
+        assert!(ctx.len() == 1, "called with unexpected number of arguments");
+        let value = try!(ctx.get::<c_double>(0));
+        Ok(value / 2f64)
+    }
+
+    #[test]
+    fn test_function_half() {
+        let db = SqliteConnection::open_in_memory().unwrap();
+        db.create_scalar_function("half", 1, true, half).unwrap();
+        let result = db.query_row("SELECT half(6)", &[], |r| r.get::<f64>(0));
+
+        assert_eq!(3f64, result.unwrap());
+    }
+
+    #[test]
+    fn test_remove_function() {
+        let db = SqliteConnection::open_in_memory().unwrap();
+        db.create_scalar_function("half", 1, true, half).unwrap();
+        let result = db.query_row("SELECT half(6)", &[], |r| r.get::<f64>(0));
+        assert_eq!(3f64, result.unwrap());
+
+        db.remove_function("half", 1).unwrap();
+        let result = db.query_row("SELECT half(6)", &[], |r| r.get::<f64>(0));
+        assert!(result.is_err());
+    }
+
+    // This implementation of a regexp scalar function uses SQLite's auxilliary data
+    // (https://www.sqlite.org/c3ref/get_auxdata.html) to avoid recompiling the regular
+    // expression multiple times within one query.
+    fn regexp_with_auxilliary(ctx: &Context) -> SqliteResult<bool> {
+        assert!(ctx.len() == 2, "called with unexpected number of arguments");
+
+        let saved_re: Option<&Regex> = unsafe { ctx.get_aux(0) };
+        let new_re = match saved_re {
+            None => {
+                let s = try!(ctx.get::<String>(0));
+                let r = try!(Regex::new(&s).map_err(|e| {
+                    SqliteError {
+                        code: ffi::SQLITE_ERROR,
+                        message: format!("Invalid regular expression: {}", e),
+                    }
+                }));
+                Some(r)
+            }
+            Some(_) => None,
+        };
+
+        let is_match = {
+            let re = saved_re.unwrap_or_else(|| new_re.as_ref().unwrap());
+
+            let text = try!(ctx.get::<String>(1));
+            re.is_match(&text)
+        };
+
+        if let Some(re) = new_re {
+            ctx.set_aux(0, re);
+        }
+
+        Ok(is_match)
+    }
+
+    #[test]
+    #[cfg_attr(rustfmt, rustfmt_skip)]
+    fn test_function_regexp_with_auxilliary() {
+        let db = SqliteConnection::open_in_memory().unwrap();
+        db.execute_batch("BEGIN;
+                         CREATE TABLE foo (x string);
+                         INSERT INTO foo VALUES ('lisa');
+                         INSERT INTO foo VALUES ('lXsi');
+                         INSERT INTO foo VALUES ('lisX');
+                         END;").unwrap();
+        db.create_scalar_function("regexp", 2, true, regexp_with_auxilliary).unwrap();
+
+        let result = db.query_row("SELECT regexp('l.s[aeiouy]', 'lisa')",
+                                  &[],
+                                  |r| r.get::<bool>(0));
+
+        assert_eq!(true, result.unwrap());
+
+        let result = db.query_row("SELECT COUNT(*) FROM foo WHERE regexp('l.s[aeiouy]', x) == 1",
+                                  &[],
+                                  |r| r.get::<i64>(0));
+
+        assert_eq!(2, result.unwrap());
+    }
+
+    #[test]
+    #[cfg_attr(rustfmt, rustfmt_skip)]
+    fn test_function_regexp_with_hashmap_cache() {
+        let db = SqliteConnection::open_in_memory().unwrap();
+        db.execute_batch("BEGIN;
+                         CREATE TABLE foo (x string);
+                         INSERT INTO foo VALUES ('lisa');
+                         INSERT INTO foo VALUES ('lXsi');
+                         INSERT INTO foo VALUES ('lisX');
+                         END;").unwrap();
+
+        // This implementation of a regexp scalar function uses a captured HashMap
+        // to keep cached regular expressions around (even across multiple queries)
+        // until the function is removed.
+        let mut cached_regexes = HashMap::new();
+        db.create_scalar_function("regexp", 2, true, move |ctx| {
+            assert!(ctx.len() == 2, "called with unexpected number of arguments");
+
+            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) => {
+                        let r = try!(Regex::new(&regex_s).map_err(|e| SqliteError {
+                            code: ffi::SQLITE_ERROR,
+                            message: format!("Invalid regular expression: {}", e),
+                        }));
+                        vac.insert(r)
+                    }
+                }
+            };
+
+            let text = try!(ctx.get::<String>(1));
+            Ok(regex.is_match(&text))
+        }).unwrap();
+
+        let result = db.query_row("SELECT regexp('l.s[aeiouy]', 'lisa')",
+                                  &[],
+                                  |r| r.get::<bool>(0));
+
+        assert_eq!(true, result.unwrap());
+
+        let result = db.query_row("SELECT COUNT(*) FROM foo WHERE regexp('l.s[aeiouy]', x) == 1",
+                                  &[],
+                                  |r| r.get::<i64>(0));
+
+        assert_eq!(2, result.unwrap());
+    }
+
+    #[test]
+    fn test_varargs_function() {
+        let db = SqliteConnection::open_in_memory().unwrap();
+        db.create_scalar_function("my_concat", -1, true, |ctx| {
+              let mut ret = String::new();
+
+              for idx in 0..ctx.len() {
+                  let s = try!(ctx.get::<String>(idx));
+                  ret.push_str(&s);
+              }
+
+              Ok(ret)
+          })
+          .unwrap();
+
+        for &(expected, query) in &[("", "SELECT my_concat()"),
+                                    ("onetwo", "SELECT my_concat('one', 'two')"),
+                                    ("abc", "SELECT my_concat('a', 'b', 'c')")] {
+            let result: String = db.query_row(query, &[], |r| r.get(0)).unwrap();
+            assert_eq!(expected, result);
+        }
+    }
+}

src/lib.rs

@@ -86,6 +86,7 @@ mod named_params;
 #[cfg(feature = "load_extension")]mod load_extension_guard;
 #[cfg(feature = "trace")]pub mod trace;
 #[cfg(feature = "backup")]pub mod backup;
+#[cfg(feature = "functions")] pub mod functions;
 
 /// A typedef of the result returned by many methods.
 pub type SqliteResult<T> = Result<T, SqliteError>;

src/types.rs

@@ -100,6 +100,15 @@ raw_to_impl!(c_int, sqlite3_bind_int);
 raw_to_impl!(i64, sqlite3_bind_int64);
 raw_to_impl!(c_double, sqlite3_bind_double);
 
+impl ToSql for bool {
+    unsafe fn bind_parameter(&self, stmt: *mut sqlite3_stmt, col: c_int) -> c_int {
+        match *self {
+            true => ffi::sqlite3_bind_int(stmt, col, 1),
+            _ => ffi::sqlite3_bind_int(stmt, col, 0),
+        }
+    }
+}
+
 impl<'a> ToSql for &'a str {
     unsafe fn bind_parameter(&self, stmt: *mut sqlite3_stmt, col: c_int) -> c_int {
         let length = self.len();
@@ -203,6 +212,19 @@ raw_from_impl!(c_int, sqlite3_column_int, ffi::SQLITE_INTEGER);
 raw_from_impl!(i64, sqlite3_column_int64, ffi::SQLITE_INTEGER);
 raw_from_impl!(c_double, sqlite3_column_double, ffi::SQLITE_FLOAT);
 
+impl FromSql for bool {
+    unsafe fn column_result(stmt: *mut sqlite3_stmt, col: c_int) -> SqliteResult<bool> {
+        match ffi::sqlite3_column_int(stmt, col) {
+            0 => Ok(false),
+            _ => Ok(true),
+        }
+    }
+
+    unsafe fn column_has_valid_sqlite_type(stmt: *mut sqlite3_stmt, col: c_int) -> bool {
+        sqlite3_column_type(stmt, col) == ffi::SQLITE_INTEGER
+    }
+}
+
 impl FromSql for String {
     unsafe fn column_result(stmt: *mut sqlite3_stmt, col: c_int) -> SqliteResult<String> {
         let c_text = ffi::sqlite3_column_text(stmt, col);