Draft for carray module in Rust

Incomplete support for sqlite3_bind_pointer.
Make Context::set_result return a Result.
Add Values::get_array.

src/functions.rs

@@ -49,6 +49,7 @@
 //!     assert!(is_match);
 //! }
 //! ```
+use std::error::Error as StdError;
 use std::ptr;
 use std::slice;
 use std::os::raw::{c_int, c_void};
@@ -57,11 +58,41 @@ use ffi;
 use ffi::sqlite3_context;
 use ffi::sqlite3_value;
 
-use context::{report_error, set_result};
+use context::{set_result};
 use types::{ToSql, FromSql, FromSqlError, ValueRef};
 
 use {Result, Error, Connection, str_to_cstring, InnerConnection};
 
+unsafe fn report_error(ctx: *mut sqlite3_context, err: &Error) {
+    // Extended constraint error codes were added in SQLite 3.7.16. We don't have an explicit
+    // feature check for that, and this doesn't really warrant one. We'll use the extended code
+    // if we're on the bundled version (since it's at least 3.17.0) and the normal constraint
+    // error code if not.
+    #[cfg(feature = "bundled")]
+    fn constraint_error_code() -> i32 {
+        ffi::SQLITE_CONSTRAINT_FUNCTION
+    }
+    #[cfg(not(feature = "bundled"))]
+    fn constraint_error_code() -> i32 {
+        ffi::SQLITE_CONSTRAINT
+    }
+
+    match *err {
+        Error::SqliteFailure(ref err, ref s) => {
+            ffi::sqlite3_result_error_code(ctx, err.extended_code);
+            if let Some(Ok(cstr)) = s.as_ref().map(|s| str_to_cstring(s)) {
+                ffi::sqlite3_result_error(ctx, cstr.as_ptr(), -1);
+            }
+        }
+        _ => {
+            ffi::sqlite3_result_error_code(ctx, constraint_error_code());
+            if let Ok(cstr) = str_to_cstring(err.description()) {
+                ffi::sqlite3_result_error(ctx, cstr.as_ptr(), -1);
+            }
+        }
+    }
+}
+
 unsafe extern "C" fn free_boxed_value<T>(p: *mut c_void) {
     let _: Box<T> = Box::from_raw(p as *mut T);
 }