Rework ToSql to be implementable without unsafe.

src/blob.rs

@@ -52,10 +52,9 @@ use std::io;
 use std::cmp::min;
 use std::mem;
 use std::ptr;
-use libc::c_int;
 
 use super::ffi;
-use super::types::ToSql;
+use super::types::{ToSql, ToSqlOutput};
 use {Result, Connection, DatabaseName};
 
 /// Handle to an open BLOB.
@@ -244,9 +243,9 @@ impl<'conn> Drop for Blob<'conn> {
 pub struct ZeroBlob(pub i32);
 
 impl ToSql for ZeroBlob {
-    unsafe fn bind_parameter(&self, stmt: *mut ffi::sqlite3_stmt, col: c_int) -> c_int {
+    fn to_sql(&self) -> Result<ToSqlOutput> {
         let ZeroBlob(length) = *self;
-        ffi::sqlite3_bind_zeroblob(stmt, col, length)
+        Ok(ToSqlOutput::ZeroBlob(length))
     }
 }
 

src/functions.rs

@@ -182,7 +182,7 @@ impl<'a> ValueRef<'a> {
 
                 ValueRef::Blob(from_raw_parts(blob as *const u8, len as usize))
             }
-            _ => unreachable!("sqlite3_value_type returned invalid value")
+            _ => unreachable!("sqlite3_value_type returned invalid value"),
         }
     }
 }
@@ -219,7 +219,7 @@ impl<'a> Context<'a> {
         let value = unsafe { ValueRef::from_value(arg) };
         FromSql::column_result(value).map_err(|err| match err {
             Error::InvalidColumnType => Error::InvalidFunctionParameterType,
-            _ => err
+            _ => err,
         })
     }
 

src/lib.rs

@@ -73,9 +73,9 @@ use std::cell::RefCell;
 use std::ffi::{CStr, CString};
 use std::result;
 use std::str;
-use libc::{c_int, c_char};
+use libc::{c_int, c_char, c_void};
 
-use types::{ToSql, FromSql, ValueRef};
+use types::{ToSql, ToSqlOutput, FromSql, ValueRef};
 use error::{error_from_sqlite_code, error_from_handle};
 use raw_statement::RawStatement;
 use cache::StatementCache;
@@ -874,6 +874,54 @@ impl<'conn> Statement<'conn> {
         self.finalize_()
     }
 
+    fn bind_parameter(&self, param: &ToSql, col: c_int) -> Result<()> {
+        // This should be
+        //   let value = try!(param.to_sql());
+        // but that hits a bug in the Rust compiler around re-exported
+        // trait visibility. It's fixed in 1.9.
+        let value = try!(ToSql::to_sql(param));
+
+        let ptr = unsafe { self.stmt.ptr() };
+        let value = match value {
+            ToSqlOutput::Borrowed(v) => v,
+            ToSqlOutput::Owned(ref v) => ValueRef::from(v),
+
+            #[cfg(feature = "blob")]
+            ToSqlOutput::ZeroBlob(len) => {
+                return self.conn.decode_result(unsafe { ffi::sqlite3_bind_zeroblob(ptr, col, len) });
+            }
+        };
+        self.conn.decode_result(match value {
+            ValueRef::Null => unsafe { ffi::sqlite3_bind_null(ptr, col) },
+            ValueRef::Integer(i) => unsafe { ffi::sqlite3_bind_int64(ptr, col, i) },
+            ValueRef::Real(r) => unsafe { ffi::sqlite3_bind_double(ptr, col, r) },
+            ValueRef::Text(ref s) => unsafe {
+                let length = s.len();
+                if length > ::std::i32::MAX as usize {
+                    ffi::SQLITE_TOOBIG
+                } else {
+                    let c_str = try!(str_to_cstring(s));
+                    let destructor = if length > 0 {
+                        ffi::SQLITE_TRANSIENT()
+                    } else {
+                        ffi::SQLITE_STATIC()
+                    };
+                    ffi::sqlite3_bind_text(ptr, col, c_str.as_ptr(), length as c_int, destructor)
+                }
+            },
+            ValueRef::Blob(ref b) => unsafe {
+                let length = b.len();
+                if length > ::std::i32::MAX as usize {
+                    ffi::SQLITE_TOOBIG
+                } else if length == 0 {
+                    ffi::sqlite3_bind_zeroblob(ptr, col, 0)
+                } else {
+                    ffi::sqlite3_bind_blob(ptr, col, b.as_ptr() as *const c_void, length as c_int, ffi::SQLITE_TRANSIENT())
+                }
+            },
+        })
+    }
+
     fn bind_parameters(&mut self, params: &[&ToSql]) -> Result<()> {
         assert!(params.len() as c_int == self.stmt.bind_parameter_count(),
                 "incorrect number of parameters to query(): expected {}, got {}",
@@ -881,14 +929,7 @@ impl<'conn> Statement<'conn> {
                 params.len());
 
         for (i, p) in params.iter().enumerate() {
-            try!(unsafe {
-                self.conn.decode_result(
-                    // This should be
-                    // `p.bind_parameter(self.stmt.ptr(), (i + 1) as c_int)`
-                    // but that doesn't compile until Rust 1.9 due to a compiler bug.
-                    ToSql::bind_parameter(*p, self.stmt.ptr(), (i + 1) as c_int)
-                )
-            });
+            try!(self.bind_parameter(*p, (i + 1) as c_int));
         }
 
         Ok(())
@@ -1128,7 +1169,7 @@ impl<'a> ValueRef<'a> {
 
                 ValueRef::Blob(from_raw_parts(blob as *const u8, len as usize))
             }
-            _ => unreachable!("sqlite3_column_type returned invalid value")
+            _ => unreachable!("sqlite3_column_type returned invalid value"),
         }
     }
 }

src/named_params.rs

@@ -204,12 +204,7 @@ impl<'conn> Statement<'conn> {
     fn bind_parameters_named(&mut self, params: &[(&str, &ToSql)]) -> Result<()> {
         for &(name, value) in params {
             if let Some(i) = try!(self.parameter_index(name)) {
-                try!(self.conn.decode_result(unsafe {
-                    // This should be
-                    // `value.bind_parameter(self.stmt.ptr(), i)`
-                    // but that doesn't compile until Rust 1.9 due to a compiler bug.
-                    ToSql::bind_parameter(value, self.stmt.ptr(), i)
-                }));
+                try!(self.bind_parameter(value, i));
             } else {
                 return Err(Error::InvalidParameterName(name.into()));
             }

src/types/chrono.rs

@@ -4,18 +4,15 @@ extern crate chrono;
 use std::borrow::Cow;
 
 use self::chrono::{NaiveDate, NaiveTime, NaiveDateTime, DateTime, TimeZone, UTC, Local};
-use libc::c_int;
 
 use {Error, Result};
-use types::{FromSql, ToSql, ValueRef};
-
-use ffi::sqlite3_stmt;
+use types::{FromSql, ToSql, ToSqlOutput, ValueRef};
 
 /// ISO 8601 calendar date without timezone => "YYYY-MM-DD"
 impl ToSql for NaiveDate {
-    unsafe fn bind_parameter(&self, stmt: *mut sqlite3_stmt, col: c_int) -> c_int {
+    fn to_sql(&self) -> Result<ToSqlOutput> {
         let date_str = self.format("%Y-%m-%d").to_string();
-        date_str.bind_parameter(stmt, col)
+        Ok(ToSqlOutput::from(date_str))
     }
 }
 
@@ -31,9 +28,9 @@ impl FromSql for NaiveDate {
 
 /// ISO 8601 time without timezone => "HH:MM:SS.SSS"
 impl ToSql for NaiveTime {
-    unsafe fn bind_parameter(&self, stmt: *mut sqlite3_stmt, col: c_int) -> c_int {
+    fn to_sql(&self) -> Result<ToSqlOutput> {
         let date_str = self.format("%H:%M:%S%.f").to_string();
-        date_str.bind_parameter(stmt, col)
+        Ok(ToSqlOutput::from(date_str))
     }
 }
 
@@ -56,9 +53,9 @@ impl FromSql for NaiveTime {
 
 /// ISO 8601 combined date and time without timezone => "YYYY-MM-DD HH:MM:SS.SSS"
 impl ToSql for NaiveDateTime {
-    unsafe fn bind_parameter(&self, stmt: *mut sqlite3_stmt, col: c_int) -> c_int {
+    fn to_sql(&self) -> Result<ToSqlOutput> {
         let date_str = self.format("%Y-%m-%dT%H:%M:%S%.f").to_string();
-        date_str.bind_parameter(stmt, col)
+        Ok(ToSqlOutput::from(date_str))
     }
 }
 
@@ -83,9 +80,8 @@ impl FromSql for NaiveDateTime {
 
 /// Date and time with time zone => UTC RFC3339 timestamp ("YYYY-MM-DDTHH:MM:SS.SSS+00:00").
 impl<Tz: TimeZone> ToSql for DateTime<Tz> {
-    unsafe fn bind_parameter(&self, stmt: *mut sqlite3_stmt, col: c_int) -> c_int {
-        let utc_dt = self.with_timezone(&UTC);
-        utc_dt.to_rfc3339().bind_parameter(stmt, col)
+    fn to_sql(&self) -> Result<ToSqlOutput> {
+        Ok(ToSqlOutput::from(self.with_timezone(&UTC).to_rfc3339()))
     }
 }
 

src/types/mod.rs

@@ -50,10 +50,8 @@
 //! `FromSql` for the cases where you want to know if a value was NULL (which gets translated to
 //! `None`).
 
-pub use ffi::sqlite3_stmt;
-
 pub use self::from_sql::FromSql;
-pub use self::to_sql::ToSql;
+pub use self::to_sql::{ToSql, ToSqlOutput};
 pub use self::value_ref::ValueRef;
 
 mod value_ref;
@@ -102,6 +100,42 @@ pub enum Value {
     Blob(Vec<u8>),
 }
 
+impl From<Null> for Value {
+    fn from(_: Null) -> Value {
+        Value::Null
+    }
+}
+
+impl From<i32> for Value {
+    fn from(i: i32) -> Value {
+        Value::Integer(i as i64)
+    }
+}
+
+impl From<i64> for Value {
+    fn from(i: i64) -> Value {
+        Value::Integer(i)
+    }
+}
+
+impl From<f64> for Value {
+    fn from(f: f64) -> Value {
+        Value::Real(f)
+    }
+}
+
+impl From<String> for Value {
+    fn from(s: String) -> Value {
+        Value::Text(s)
+    }
+}
+
+impl From<Vec<u8>> for Value {
+    fn from(v: Vec<u8>) -> Value {
+        Value::Blob(v)
+    }
+}
+
 #[cfg(test)]
 #[cfg_attr(feature="clippy", allow(similar_names))]
 mod test {
@@ -111,6 +145,7 @@ mod test {
     use Error;
     use libc::{c_int, c_double};
     use std::f64::EPSILON;
+    use super::Value;
 
     fn checked_memory_handle() -> Connection {
         let db = Connection::open_in_memory().unwrap();
@@ -133,6 +168,17 @@ mod test {
     fn test_str() {
         let db = checked_memory_handle();
 
+        let s = "hello, world!";
+        db.execute("INSERT INTO foo(t) VALUES (?)", &[&s]).unwrap();
+
+        let from: String = db.query_row("SELECT t FROM foo", &[], |r| r.get(0)).unwrap();
+        assert_eq!(from, s);
+    }
+
+    #[test]
+    fn test_string() {
+        let db = checked_memory_handle();
+
         let s = "hello, world!";
         db.execute("INSERT INTO foo(t) VALUES (?)", &[&s.to_owned()]).unwrap();
 
@@ -140,6 +186,15 @@ mod test {
         assert_eq!(from, s);
     }
 
+    #[test]
+    fn test_value() {
+        let db = checked_memory_handle();
+
+        db.execute("INSERT INTO foo(i) VALUES (?)", &[&Value::Integer(10)]).unwrap();
+
+        assert_eq!(10i64, db.query_row("SELECT i FROM foo", &[], |r| r.get(0)).unwrap());
+    }
+
     #[test]
     fn test_option() {
         let db = checked_memory_handle();

src/types/serde_json.rs

@@ -1,19 +1,15 @@
 //! `ToSql` and `FromSql` implementation for JSON `Value`.
 extern crate serde_json;
 
-use libc::c_int;
 use self::serde_json::Value;
 
 use {Error, Result};
-use types::{FromSql, ToSql, ValueRef};
-
-use ffi::sqlite3_stmt;
+use types::{FromSql, ToSql, ToSqlOutput, ValueRef};
 
 /// Serialize JSON `Value` to text.
 impl ToSql for Value {
-    unsafe fn bind_parameter(&self, stmt: *mut sqlite3_stmt, col: c_int) -> c_int {
-        let s = serde_json::to_string(self).unwrap();
-        s.bind_parameter(stmt, col)
+    fn to_sql(&self) -> Result<ToSqlOutput> {
+        Ok(ToSqlOutput::from(serde_json::to_string(self).unwrap()))
     }
 }
 
@@ -21,10 +17,11 @@ impl ToSql for Value {
 impl FromSql for Value {
     fn column_result(value: ValueRef) -> Result<Self> {
         match value {
-            ValueRef::Text(ref s) => serde_json::from_str(s),
-            ValueRef::Blob(ref b) => serde_json::from_slice(b),
-            _ => return Err(Error::InvalidColumnType),
-        }.map_err(|err| Error::FromSqlConversionFailure(Box::new(err)))
+                ValueRef::Text(ref s) => serde_json::from_str(s),
+                ValueRef::Blob(ref b) => serde_json::from_slice(b),
+                _ => return Err(Error::InvalidColumnType),
+            }
+            .map_err(|err| Error::FromSqlConversionFailure(Box::new(err)))
     }
 }
 

src/types/time.rs

@@ -1,17 +1,14 @@
 extern crate time;
 
-use libc::c_int;
 use {Error, Result};
-use types::{FromSql, ToSql, ValueRef};
-
-use ffi::sqlite3_stmt;
+use types::{FromSql, ToSql, ToSqlOutput, ValueRef};
 
 const SQLITE_DATETIME_FMT: &'static str = "%Y-%m-%d %H:%M:%S";
 
 impl ToSql for time::Timespec {
-    unsafe fn bind_parameter(&self, stmt: *mut sqlite3_stmt, col: c_int) -> c_int {
-        let time_str = time::at_utc(*self).strftime(SQLITE_DATETIME_FMT).unwrap().to_string();
-        time_str.bind_parameter(stmt, col)
+    fn to_sql(&self) -> Result<ToSqlOutput> {
+        let time_string = time::at_utc(*self).strftime(SQLITE_DATETIME_FMT).unwrap().to_string();
+        Ok(ToSqlOutput::from(time_string))
     }
 }
 

src/types/to_sql.rs

@@ -1,95 +1,87 @@
-use std::mem;
+use super::{Null, Value, ValueRef};
+use ::Result;
 
-use libc::{c_double, c_int};
+pub enum ToSqlOutput<'a> {
+    Borrowed(ValueRef<'a>),
+    Owned(Value),
 
-use super::Null;
-use ::{ffi, str_to_cstring};
-use ffi::sqlite3_stmt;
+    #[cfg(feature = "blob")]
+    ZeroBlob(i32),
+}
+
+impl<'a, T: ?Sized> From<&'a T> for ToSqlOutput<'a> where &'a T: Into<ValueRef<'a>> {
+    fn from(t: &'a T) -> Self {
+        ToSqlOutput::Borrowed(t.into())
+    }
+}
+
+impl<'a, T: Into<Value>> From<T> for ToSqlOutput<'a> {
+    fn from(t: T) -> Self {
+        ToSqlOutput::Owned(t.into())
+    }
+}
 
 /// A trait for types that can be converted into SQLite values.
 pub trait ToSql {
-    unsafe fn bind_parameter(&self, stmt: *mut sqlite3_stmt, col: c_int) -> c_int;
+    fn to_sql(&self) -> Result<ToSqlOutput>;
 }
 
-macro_rules! raw_to_impl(
-    ($t:ty, $f:ident) => (
+// We should be able to use a generic impl like this:
+//
+// impl<T: Copy> ToSql for T where T: Into<Value> {
+//     fn to_sql(&self) -> Result<ToSqlOutput> {
+//         Ok(ToSqlOutput::from((*self).into()))
+//     }
+// }
+//
+// instead of the following macro, but this runs afoul of
+// https://github.com/rust-lang/rust/issues/30191 and reports conflicting
+// implementations even when there aren't any.
+
+macro_rules! to_sql_self(
+    ($t:ty) => (
         impl ToSql for $t {
-            unsafe fn bind_parameter(&self, stmt: *mut sqlite3_stmt, col: c_int) -> c_int {
-                ffi::$f(stmt, col, *self)
+            fn to_sql(&self) -> Result<ToSqlOutput> {
+                Ok(ToSqlOutput::from(*self))
             }
         }
     )
 );
 
-raw_to_impl!(c_int, sqlite3_bind_int); // i32
-raw_to_impl!(i64, sqlite3_bind_int64);
-raw_to_impl!(c_double, sqlite3_bind_double);
+to_sql_self!(Null);
+to_sql_self!(i32);
+to_sql_self!(i64);
+to_sql_self!(f64);
 
-impl ToSql for bool {
-    unsafe fn bind_parameter(&self, stmt: *mut sqlite3_stmt, col: c_int) -> c_int {
-        if *self {
-            ffi::sqlite3_bind_int(stmt, col, 1)
-        } else {
-            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();
-        if length > ::std::i32::MAX as usize {
-            return ffi::SQLITE_TOOBIG;
-        }
-        match str_to_cstring(self) {
-            Ok(c_str) => {
-                ffi::sqlite3_bind_text(stmt,
-                                       col,
-                                       c_str.as_ptr(),
-                                       length as c_int,
-                                       ffi::SQLITE_TRANSIENT())
-            }
-            Err(_) => ffi::SQLITE_MISUSE,
-        }
+impl<'a, T: ?Sized> ToSql for &'a T where &'a T: Into<ToSqlOutput<'a>> {
+    fn to_sql(&self) -> Result<ToSqlOutput> {
+        Ok(ToSqlOutput::from((*self).into()))
     }
 }
 
 impl ToSql for String {
-    unsafe fn bind_parameter(&self, stmt: *mut sqlite3_stmt, col: c_int) -> c_int {
-        (&self[..]).bind_parameter(stmt, col)
-    }
-}
-
-impl<'a> ToSql for &'a [u8] {
-    unsafe fn bind_parameter(&self, stmt: *mut sqlite3_stmt, col: c_int) -> c_int {
-        if self.len() > ::std::i32::MAX as usize {
-            return ffi::SQLITE_TOOBIG;
-        }
-        ffi::sqlite3_bind_blob(stmt,
-                               col,
-                               mem::transmute(self.as_ptr()),
-                               self.len() as c_int,
-                               ffi::SQLITE_TRANSIENT())
+    fn to_sql(&self) -> Result<ToSqlOutput> {
+        Ok(ToSqlOutput::from(self.as_str()))
     }
 }
 
 impl ToSql for Vec<u8> {
-    unsafe fn bind_parameter(&self, stmt: *mut sqlite3_stmt, col: c_int) -> c_int {
-        (&self[..]).bind_parameter(stmt, col)
+    fn to_sql(&self) -> Result<ToSqlOutput> {
+        Ok(ToSqlOutput::from(self.as_slice()))
+    }
+}
+
+impl ToSql for Value {
+    fn to_sql(&self) -> Result<ToSqlOutput> {
+        Ok(ToSqlOutput::from(self))
     }
 }
 
 impl<T: ToSql> ToSql for Option<T> {
-    unsafe fn bind_parameter(&self, stmt: *mut sqlite3_stmt, col: c_int) -> c_int {
+    fn to_sql(&self) -> Result<ToSqlOutput> {
         match *self {
-            None => ffi::sqlite3_bind_null(stmt, col),
-            Some(ref t) => t.bind_parameter(stmt, col),
+            None => Ok(ToSqlOutput::from(Null)),
+            Some(ref t) => t.to_sql(),
         }
     }
 }
-
-impl ToSql for Null {
-    unsafe fn bind_parameter(&self, stmt: *mut sqlite3_stmt, col: c_int) -> c_int {
-        ffi::sqlite3_bind_null(stmt, col)
-    }
-}

src/types/value_ref.rs

@@ -70,6 +70,18 @@ impl<'a> From<ValueRef<'a>> for Value {
     }
 }
 
+impl<'a> From<&'a str> for ValueRef<'a> {
+    fn from(s: &str) -> ValueRef {
+        ValueRef::Text(s)
+    }
+}
+
+impl<'a> From<&'a [u8]> for ValueRef<'a> {
+    fn from(s: &[u8]) -> ValueRef {
+        ValueRef::Blob(s)
+    }
+}
+
 impl<'a> From<&'a Value> for ValueRef<'a> {
     fn from(value: &'a Value) -> ValueRef<'a> {
         match *value {