Make Rows implement FallibleStreamingIterator

Cargo.toml

@@ -47,7 +47,7 @@ csvtab = ["csv", "vtab"]
 # pointer passing interfaces: 3.20.0
 array = ["vtab"]
 # session extension: 3.13.0
-session = ["libsqlite3-sys/session", "hooks", "fallible-streaming-iterator"]
+session = ["libsqlite3-sys/session", "hooks"]
 
 [dependencies]
 time = "0.1.0"
@@ -58,7 +58,7 @@ serde_json = { version = "1.0", optional = true }
 csv = { version = "1.0", optional = true }
 lazy_static = { version = "1.0", optional = true }
 byteorder = { version = "1.2", features = ["i128"], optional = true }
-fallible-streaming-iterator = { version = "0.1", optional = true }
+fallible-streaming-iterator = "0.1"
 
 [dev-dependencies]
 tempdir = "0.3"

src/lib.rs

@@ -80,6 +80,8 @@ use std::str;
 use std::sync::atomic::Ordering;
 use std::sync::{Arc, Mutex};
 
+pub use fallible_streaming_iterator::FallibleStreamingIterator;
+
 use crate::cache::StatementCache;
 use crate::inner_connection::{InnerConnection, BYPASS_SQLITE_INIT};
 use crate::raw_statement::RawStatement;
@@ -89,7 +91,7 @@ pub use crate::cache::CachedStatement;
 pub use crate::error::Error;
 pub use crate::ffi::ErrorCode;
 #[cfg(feature = "hooks")]
-pub use crate::hooks::*;
+pub use crate::hooks::Action;
 #[cfg(feature = "load_extension")]
 pub use crate::load_extension_guard::LoadExtensionGuard;
 pub use crate::row::{AndThenRows, MappedRows, Row, RowIndex, Rows};
@@ -474,7 +476,7 @@ impl Connection {
     where
         P: IntoIterator,
         P::Item: ToSql,
-        F: FnOnce(&Row<'_, '_>) -> T,
+        F: FnOnce(&Row<'_>) -> T,
     {
         let mut stmt = self.prepare(sql)?;
         stmt.query_row(params, f)
@@ -496,7 +498,7 @@ impl Connection {
     /// or if the underlying SQLite call fails.
     pub fn query_row_named<T, F>(&self, sql: &str, params: &[(&str, &dyn ToSql)], f: F) -> Result<T>
     where
-        F: FnOnce(&Row<'_, '_>) -> T,
+        F: FnOnce(&Row<'_>) -> T,
     {
         let mut stmt = self.prepare(sql)?;
         let mut rows = stmt.query_named(params)?;
@@ -533,7 +535,7 @@ impl Connection {
     where
         P: IntoIterator,
         P::Item: ToSql,
-        F: FnOnce(&Row<'_, '_>) -> result::Result<T, E>,
+        F: FnOnce(&Row<'_>) -> result::Result<T, E>,
         E: convert::From<Error>,
     {
         let mut stmt = self.prepare(sql)?;
@@ -1061,8 +1063,8 @@ mod test {
             let mut rows = query.query(&[4i32]).unwrap();
             let mut v = Vec::<i32>::new();
 
-            while let Some(row) = rows.next() {
+            while let Some(row) = rows.next().unwrap() {
-                v.push(row.unwrap().get(0));
+                v.push(row.get(0));
             }
 
             assert_eq!(v, [3i32, 2, 1]);
@@ -1072,8 +1074,8 @@ mod test {
             let mut rows = query.query(&[3i32]).unwrap();
             let mut v = Vec::<i32>::new();
 
-            while let Some(row) = rows.next() {
+            while let Some(row) = rows.next().unwrap() {
-                v.push(row.unwrap().get(0));
+                v.push(row.get(0));
             }
 
             assert_eq!(v, [2i32, 1]);
@@ -1215,7 +1217,7 @@ mod test {
         {
             let mut rows = stmt.query(NO_PARAMS).unwrap();
             assert!(!db.is_busy());
-            let row = rows.next();
+            let row = rows.next().unwrap();
             assert!(db.is_busy());
             assert!(row.is_some());
         }
@@ -1327,8 +1329,7 @@ mod test {
         let mut query = db.prepare("SELECT i, x FROM foo").unwrap();
         let mut rows = query.query(NO_PARAMS).unwrap();
 
-        while let Some(res) = rows.next() {
+        while let Some(row) = rows.next().unwrap() {
-            let row = res.unwrap();
             let i = row.get_raw(0).as_i64().unwrap();
             let expect = vals[i as usize];
             let x = row.get_raw("x").as_str().unwrap();

src/row.rs

@@ -1,12 +1,12 @@
-use std::marker::PhantomData;
 use std::{convert, result};
 
-use super::{Error, Result, Statement};
+use super::{Error, FallibleStreamingIterator, Result, Statement};
 use crate::types::{FromSql, FromSqlError, ValueRef};
 
 /// An handle for the resulting rows of a query.
 pub struct Rows<'stmt> {
     stmt: Option<&'stmt Statement<'stmt>>,
+    row: Option<Row<'stmt>>,
 }
 
 impl<'stmt> Rows<'stmt> {
@@ -15,45 +15,19 @@ impl<'stmt> Rows<'stmt> {
             stmt.reset();
         }
     }
-
-    /// Attempt to get the next row from the query. Returns `Some(Ok(Row))` if
-    /// there is another row, `Some(Err(...))` if there was an error
-    /// getting the next row, and `None` if all rows have been retrieved.
-    ///
-    /// ## Note
-    ///
-    /// This interface is not compatible with Rust's `Iterator` trait, because
-    /// the lifetime of the returned row is tied to the lifetime of `self`.
-    /// This is a "streaming iterator". For a more natural interface,
-    /// consider using `query_map` or `query_and_then` instead, which
-    /// return types that implement `Iterator`.
-    #[allow(clippy::should_implement_trait)] // cannot implement Iterator
-    pub fn next<'a>(&'a mut self) -> Option<Result<Row<'a, 'stmt>>> {
-        self.stmt.and_then(|stmt| match stmt.step() {
-            Ok(true) => Some(Ok(Row {
-                stmt,
-                phantom: PhantomData,
-            })),
-            Ok(false) => {
-                self.reset();
-                None
-            }
-            Err(err) => {
-                self.reset();
-                Some(Err(err))
-            }
-        })
-    }
 }
 
 impl<'stmt> Rows<'stmt> {
     pub(crate) fn new(stmt: &'stmt Statement<'stmt>) -> Rows<'stmt> {
-        Rows { stmt: Some(stmt) }
+        Rows {
+            stmt: Some(stmt),
+            row: None,
+        }
     }
 
-    pub(crate) fn get_expected_row<'a>(&'a mut self) -> Result<Row<'a, 'stmt>> {
+    pub(crate) fn get_expected_row(&mut self) -> Result<&Row<'stmt>> {
-        match self.next() {
+        match self.next()? {
-            Some(row) => row,
+            Some(row) => Ok(row),
             None => Err(Error::QueryReturnedNoRows),
         }
     }
@@ -73,7 +47,7 @@ pub struct MappedRows<'stmt, F> {
 
 impl<'stmt, T, F> MappedRows<'stmt, F>
 where
-    F: FnMut(&Row<'_, '_>) -> T,
+    F: FnMut(&Row<'_>) -> T,
 {
     pub(crate) fn new(rows: Rows<'stmt>, f: F) -> MappedRows<'stmt, F> {
         MappedRows { rows, map: f }
@@ -82,7 +56,7 @@ where
 
 impl<T, F> Iterator for MappedRows<'_, F>
 where
-    F: FnMut(&Row<'_, '_>) -> T,
+    F: FnMut(&Row<'_>) -> T,
 {
     type Item = Result<T>;
 
@@ -90,6 +64,7 @@ where
         let map = &mut self.map;
         self.rows
             .next()
+            .transpose()
             .map(|row_result| row_result.map(|row| (map)(&row)))
     }
 }
@@ -103,7 +78,7 @@ pub struct AndThenRows<'stmt, F> {
 
 impl<'stmt, T, E, F> AndThenRows<'stmt, F>
 where
-    F: FnMut(&Row<'_, '_>) -> result::Result<T, E>,
+    F: FnMut(&Row<'_>) -> result::Result<T, E>,
 {
     pub(crate) fn new(rows: Rows<'stmt>, f: F) -> AndThenRows<'stmt, F> {
         AndThenRows { rows, map: f }
@@ -113,7 +88,7 @@ where
 impl<T, E, F> Iterator for AndThenRows<'_, F>
 where
     E: convert::From<Error>,
-    F: FnMut(&Row<'_, '_>) -> result::Result<T, E>,
+    F: FnMut(&Row<'_>) -> result::Result<T, E>,
 {
     type Item = result::Result<T, E>;
 
@@ -121,17 +96,51 @@ where
         let map = &mut self.map;
         self.rows
             .next()
+            .transpose()
             .map(|row_result| row_result.map_err(E::from).and_then(|row| (map)(&row)))
     }
 }
 
-/// A single result row of a query.
+impl<'stmt> FallibleStreamingIterator for Rows<'stmt> {
-pub struct Row<'a, 'stmt: 'a> {
+    type Error = Error;
-    stmt: &'stmt Statement<'stmt>,
+    type Item = Row<'stmt>;
-    phantom: PhantomData<&'a ()>,
+
+    fn advance(&mut self) -> Result<()> {
+        match self.stmt {
+            Some(ref stmt) => match stmt.step() {
+                Ok(true) => {
+                    self.row = Some(Row { stmt });
+                    Ok(())
+                }
+                Ok(false) => {
+                    self.reset();
+                    self.row = None;
+                    Ok(())
+                }
+                Err(e) => {
+                    self.reset();
+                    self.row = None;
+                    Err(e)
+                }
+            },
+            None => {
+                self.row = None;
+                Ok(())
+            }
+        }
+    }
+
+    fn get(&self) -> Option<&Row<'stmt>> {
+        self.row.as_ref()
+    }
 }
 
-impl<'a, 'stmt> Row<'a, 'stmt> {
+/// A single result row of a query.
+pub struct Row<'stmt> {
+    stmt: &'stmt Statement<'stmt>,
+}
+
+impl<'stmt> Row<'stmt> {
     /// Get the value of a particular column of the result row.
     ///
     /// ## Failure
@@ -193,7 +202,7 @@ impl<'a, 'stmt> Row<'a, 'stmt> {
     ///
     /// Returns an `Error::InvalidColumnName` if `idx` is not a valid column
     /// name for this row.
-    pub fn get_raw_checked<I: RowIndex>(&self, idx: I) -> Result<ValueRef<'a>> {
+    pub fn get_raw_checked<I: RowIndex>(&self, idx: I) -> Result<ValueRef<'_>> {
         let idx = idx.idx(self.stmt)?;
         // Narrowing from `ValueRef<'stmt>` (which `self.stmt.value_ref(idx)`
         // returns) to `ValueRef<'a>` is needed because it's only valid until
@@ -217,7 +226,7 @@ impl<'a, 'stmt> Row<'a, 'stmt> {
     ///
     ///    * If `idx` is outside the range of columns in the returned query.
     ///    * If `idx` is not a valid column name for this row.
-    pub fn get_raw<I: RowIndex>(&self, idx: I) -> ValueRef<'a> {
+    pub fn get_raw<I: RowIndex>(&self, idx: I) -> ValueRef<'_> {
         self.get_raw_checked(idx).unwrap()
     }
 

src/session.rs

@@ -10,13 +10,13 @@ use std::panic::{catch_unwind, RefUnwindSafe};
 use std::ptr;
 use std::slice::{from_raw_parts, from_raw_parts_mut};
 
-use fallible_streaming_iterator::FallibleStreamingIterator;
-
 use crate::error::error_from_sqlite_code;
 use crate::ffi;
 use crate::hooks::Action;
 use crate::types::ValueRef;
-use crate::{errmsg_to_string, str_to_cstring, Connection, DatabaseName, Result};
+use crate::{
+    errmsg_to_string, str_to_cstring, Connection, DatabaseName, FallibleStreamingIterator, Result,
+};
 
 // https://sqlite.org/session.html
 
@@ -719,12 +719,11 @@ unsafe extern "C" fn x_output(p_out: *mut c_void, data: *const c_void, len: c_in
 
 #[cfg(test)]
 mod test {
-    use fallible_streaming_iterator::FallibleStreamingIterator;
     use std::sync::atomic::{AtomicBool, Ordering};
 
     use super::{Changeset, ChangesetIter, ConflictAction, ConflictType, Session};
     use crate::hooks::Action;
-    use crate::Connection;
+    use crate::{Connection, FallibleStreamingIterator};
 
     fn one_changeset() -> Changeset {
         let db = Connection::open_in_memory().unwrap();

src/statement.rs

@@ -9,7 +9,8 @@ use std::{convert, fmt, mem, ptr, result, str};
 use super::ffi;
 use super::str_to_cstring;
 use super::{
-    AndThenRows, Connection, Error, MappedRows, RawStatement, Result, Row, Rows, ValueRef,
+    AndThenRows, Connection, Error, FallibleStreamingIterator, MappedRows, RawStatement, Result,
+    Row, Rows, ValueRef,
 };
 use crate::types::{ToSql, ToSqlOutput};
 #[cfg(feature = "array")]
@@ -267,7 +268,7 @@ impl Statement<'_> {
     where
         P: IntoIterator,
         P::Item: ToSql,
-        F: FnMut(&Row<'_, '_>) -> T,
+        F: FnMut(&Row<'_>) -> T,
     {
         let rows = self.query(params)?;
         Ok(MappedRows::new(rows, f))
@@ -306,7 +307,7 @@ impl Statement<'_> {
         f: F,
     ) -> Result<MappedRows<'_, F>>
     where
-        F: FnMut(&Row<'_, '_>) -> T,
+        F: FnMut(&Row<'_>) -> T,
     {
         let rows = self.query_named(params)?;
         Ok(MappedRows::new(rows, f))
@@ -324,7 +325,7 @@ impl Statement<'_> {
         P: IntoIterator,
         P::Item: ToSql,
         E: convert::From<Error>,
-        F: FnMut(&Row<'_, '_>) -> result::Result<T, E>,
+        F: FnMut(&Row<'_>) -> result::Result<T, E>,
     {
         let rows = self.query(params)?;
         Ok(AndThenRows::new(rows, f))
@@ -375,7 +376,7 @@ impl Statement<'_> {
     ) -> Result<AndThenRows<'_, F>>
     where
         E: convert::From<Error>,
-        F: FnMut(&Row<'_, '_>) -> result::Result<T, E>,
+        F: FnMut(&Row<'_>) -> result::Result<T, E>,
     {
         let rows = self.query_named(params)?;
         Ok(AndThenRows::new(rows, f))
@@ -389,7 +390,7 @@ impl Statement<'_> {
         P::Item: ToSql,
     {
         let mut rows = self.query(params)?;
-        let exists = rows.next().is_some();
+        let exists = rows.next()?.is_some();
         Ok(exists)
     }
 
@@ -410,7 +411,7 @@ impl Statement<'_> {
     where
         P: IntoIterator,
         P::Item: ToSql,
-        F: FnOnce(&Row<'_, '_>) -> T,
+        F: FnOnce(&Row<'_>) -> T,
     {
         let mut rows = self.query(params)?;
 
@@ -732,7 +733,7 @@ pub enum StatementStatus {
 #[cfg(test)]
 mod test {
     use crate::types::ToSql;
-    use crate::{Connection, Error, Result, NO_PARAMS};
+    use crate::{Connection, Error, FallibleStreamingIterator, Result, NO_PARAMS};
 
     #[test]
     fn test_execute_named() {

src/types/mod.rs

@@ -110,7 +110,7 @@ mod test {
     use time;
 
     use super::Value;
-    use crate::{Connection, Error, NO_PARAMS};
+    use crate::{Connection, Error, FallibleStreamingIterator, NO_PARAMS};
     use std::f64::EPSILON;
     use std::os::raw::{c_double, c_int};
 

src/vtab/csvtab.rs

@@ -346,7 +346,7 @@ impl From<csv::Error> for Error {
 #[cfg(test)]
 mod test {
     use crate::vtab::csvtab;
-    use crate::{Connection, Result, NO_PARAMS};
+    use crate::{Connection, FallibleStreamingIterator, Result, NO_PARAMS};
 
     #[test]
     fn test_csv_module() {