Updated dependencies and fixed linter warnings

Cargo.toml

@@ -30,23 +30,26 @@ required-features = ["bin"]
 [features]
 bin = ["measure_time", "pretty_env_logger"]
 
+[profile.release]
+lto = true
+
 [dependencies]
-ironsea_index = "^0.1"
-ironsea_index_sfc_dbc = "^0.1"
-ironsea_index_hashmap = "^0.1"
+ironsea_index = "0.1"
+ironsea_index_sfc_dbc = "0.1"
+ironsea_index_hashmap = "0.1"
 
-arrayref = "^0.3" # For Positions Objects
-lazy_static = "^1.3"
-memmap = "^0.7"
+arrayref = "0.3" # For Positions Objects
+lazy_static = "1.5"
+memmap = "0.7"
 
-serde = { version = "^1.0", features = ["derive"] }
-serde_json = "^1.0"
-bincode = "^1.1"
+serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0"
+bincode = "1.3"
 
 # Logging macros API
-#log = { version = "^0.4", features = ["max_level_trace", "release_max_level_info"] }
-log = { version = "^0.4", features = ["max_level_trace", "release_max_level_trace"] }
+#log = { version = "0.4", features = ["max_level_trace", "release_max_level_info"] }
+log = { version = "0.4", features = ["max_level_trace", "release_max_level_trace"] }
 
 # Used for main.rs as integration test
-pretty_env_logger = { version = "^0.3", optional = true }       # Logger implementation
-measure_time = { version = "^0.6", optional = true }  # To mesure parsing time, only required by binary
+pretty_env_logger = { version = "0.5", optional = true }       # Logger implementation
+measure_time = { version = "0.8", optional = true }  # To mesure parsing time, only required by binary

src/database/db_core.rs

@@ -7,6 +7,8 @@ use super::space::Space;
 use super::space_db::SpaceDB;
 use super::space_index::SpaceSetObject;
 use super::DataBase;
+use super::IterObjects;
+use super::IterPositions;
 use super::ResultSet;
 
 /// Query Parameters.
@@ -174,11 +176,7 @@ impl Core {
 
         // We cannot return less that the total number of individual Ids stored
         // in the index for a full-volume query.
-        let max_elements = if let Some(elem) = max_elements {
-            Some(elem.max(properties.len()))
-        } else {
-            None
-        };
+        let max_elements = max_elements.map(|elem| elem.max(properties.len()));
 
         for space in spaces {
             // Filter the points of this space, and encode them before creating the index.
@@ -194,7 +192,7 @@ impl Core {
                 object.set_position(space.encode(&position)?);
             }
 
-            space_dbs.push(SpaceDB::new(&space, filtered, scales.clone(), max_elements))
+            space_dbs.push(SpaceDB::new(space, filtered, scales.clone(), max_elements))
         }
 
         Ok(Core {
@@ -220,31 +218,37 @@ impl Core {
         &self.properties
     }
 
-    fn decode_positions(
-        list: &mut [(Position, &Properties)],
-        space: &Space,
-        db: &DataBase,
+    fn decode_positions<'b>(
+        list: IterObjects<'b>,
+        space: &'b Space,
+        db: &'b DataBase,
         output_space: &Option<&str>,
-    ) -> Result<(), String> {
-        if let Some(unified_id) = *output_space {
+    ) -> Result<IterObjects<'b>, String> {
+        let b: IterObjects = if let Some(unified_id) = *output_space {
             let unified = db.space(unified_id)?;
 
             // Rebase the point to the requested output space before decoding.
-            for (position, _) in list {
-                *position = unified
-                    .decode(&Space::change_base(&position, space, unified)?)?
-                    .into();
+            Box::new(list.filter_map(move |(position, properties)| {
+                match Space::change_base(&position, space, unified) {
+                    Err(_) => None,
+                    Ok(rebased) => match unified.decode(&rebased) {
+                        Err(_) => None,
+                        Ok(decoded) => Some((decoded.into(), properties)),
+                    },
                 }
+            }))
         } else {
             // Decode the positions into f64 values, which are defined in their
             // respective reference space.
-            for (position, _) in list {
-                // Simply decode
-                *position = space.decode(&position)?.into();
-            }
-        }
+            Box::new(list.filter_map(
+                move |(position, properties)| match space.decode(&position) {
+                    Err(_) => None,
+                    Ok(decoded) => Some((decoded.into(), properties)),
+                },
+            ))
+        };
 
-        Ok(())
+        Ok(b)
     }
 
     /// Retrieve everything located at specific positions.
@@ -262,46 +266,57 @@ impl Core {
     ///     reference space.
     ///
     /// [shape]: space/enum.Shape.html
-    pub fn get_by_positions(
-        &self,
-        parameters: &CoreQueryParameters,
-        positions: &[Position],
-        space_id: &str,
-    ) -> ResultSet {
+    pub fn get_by_positions<'d>(
+        &'d self,
+        parameters: &'d CoreQueryParameters,
+        positions: Vec<Position>,
+        space_id: &'d str,
+    ) -> ResultSet<'d> {
         let CoreQueryParameters {
             db, output_space, ..
         } = parameters;
 
         let mut results = vec![];
-        let count = positions.len();
         let from = db.space(space_id)?;
 
-        // Filter positions based on the view port, if present
-        let filtered = match parameters.view_port(from) {
-            None => positions.iter().map(|p| p).collect::<Vec<_>>(),
-            Some(view_port) => positions
-                .iter()
-                .filter(|&p| view_port.contains(p))
-                .collect::<Vec<_>>(),
-        };
-
         for s in &self.space_db {
             let to = db.space(s.name())?;
-            let mut p = Vec::with_capacity(count);
 
-            for position in filtered.as_slice() {
-                let position: Vec<f64> = Space::change_base(position, from, to)?.into();
-                p.push(to.encode(&position)?);
-            }
-
-            let mut r = s
-                .get_by_positions(&p, parameters)?
+            // Filter positions based on the view port, if present
+            // FIXME: remove clone() on positions?
+            let filtered: IterPositions = match parameters.view_port(from) {
+                None => Box::new(positions.clone().into_iter()),
+                Some(view_port) => Box::new(
+                    positions
+                        .clone()
                         .into_iter()
-                .map(|(position, fields)| (position, &self.properties[fields.value()]))
-                .collect::<Vec<_>>();
-            Self::decode_positions(r.as_mut_slice(), to, db, output_space)?;
+                        .filter(move |p| view_port.contains(p)),
+                ),
+            };
 
-            results.push((s.name(), r));
+            // Rebase the positions into the current space
+            let p = filtered.filter_map(move |position| {
+                match Space::change_base(&position, from, to) {
+                    Err(_) => None,
+                    Ok(position) => {
+                        let position: Vec<f64> = position.into();
+                        match to.encode(&position) {
+                            Err(_) => None,
+                            Ok(position) => Some(position),
+                        }
+                    }
+                }
+            });
+
+            // Select the data based on the rebased viewport filter.
+            let r = s
+                .get_by_positions(p, parameters)?
+                .map(move |(position, fields)| (position, &self.properties[fields.value()]));
+
+            results.push((
+                s.name(),
+                Self::decode_positions(Box::new(r), to, db, output_space)?,
+            ));
         }
 
         Ok(results)
@@ -322,12 +337,12 @@ impl Core {
     ///     reference space.
     ///
     /// [shape]: space/enum.Shape.html
-    pub fn get_by_shape(
-        &self,
-        parameters: &CoreQueryParameters,
-        shape: &Shape,
-        space_id: &str,
-    ) -> ResultSet {
+    pub fn get_by_shape<'d>(
+        &'d self,
+        parameters: &'d CoreQueryParameters,
+        shape: Shape,
+        space_id: &'d str,
+    ) -> ResultSet<'d> {
         let CoreQueryParameters {
             db, output_space, ..
         } = parameters;
@@ -343,14 +358,14 @@ impl Core {
             //            let current_shape = shape.encode(current_space)?;
             //            println!("current shape Encoded: {:?}", current_shape);
 
-            let mut r = s
-                .get_by_shape(&current_shape, parameters)?
-                .into_iter()
-                .map(|(position, fields)| (position, &self.properties[fields.value()]))
-                .collect::<Vec<_>>();
-            Self::decode_positions(r.as_mut_slice(), current_space, db, output_space)?;
+            let r = s
+                .get_by_shape(current_shape, parameters)?
+                .map(move |(position, fields)| (position, &self.properties[fields.value()]));
 
-            results.push((s.name(), r));
+            results.push((
+                s.name(),
+                Self::decode_positions(Box::new(r), current_space, db, output_space)?,
+            ));
         }
 
         Ok(results)
@@ -366,11 +381,11 @@ impl Core {
     ///  * `id`:
     ///     Identifier for which to retrieve is positions.
     ///
-    pub fn get_by_id<S>(
-        &self,
-        parameters: &CoreQueryParameters,
+    pub fn get_by_id<'s, S>(
+        &'s self,
+        parameters: &'s CoreQueryParameters,
         id: S,
-    ) -> Result<Vec<(&String, Vec<Position>)>, String>
+    ) -> Result<Vec<(&String, IterPositions<'s>)>, String>
     where
         S: Into<String>,
     {
@@ -391,26 +406,32 @@ impl Core {
             for s in &self.space_db {
                 let current_space = db.space(s.name())?;
 
-                let mut positions = s.get_by_id(offset, parameters)?;
+                let positions_by_id = s.get_by_id(offset, parameters)?;
 
                 //Self::decode_positions(r.as_mut_slice(), current_space, db, output_space)?;
-                if let Some(unified_id) = *output_space {
+                let positions: IterPositions = if let Some(unified_id) = *output_space {
                     let unified = db.space(unified_id)?;
 
                     // Rebase the point to the requested output space before decoding.
-                    for position in &mut positions {
-                        *position = unified
-                            .decode(&Space::change_base(position, current_space, unified)?)?
-                            .into();
+                    Box::new(positions_by_id.filter_map(move |position| {
+                        match Space::change_base(&position, current_space, unified) {
+                            Err(_) => None,
+                            Ok(rebased) => match unified.decode(&rebased) {
+                                Err(_) => None,
+                                Ok(decoded) => Some(decoded.into()),
+                            },
                         }
+                    }))
                 } else {
                     // Decode the positions into f64 values, which are defined in their
                     // respective reference space.
-                    for position in &mut positions {
-                        // Simply decode
-                        *position = current_space.decode(position)?.into();
-                    }
+                    Box::new(positions_by_id.filter_map(move |position| {
+                        match current_space.decode(&position) {
+                            Err(_) => None,
+                            Ok(decoded) => Some(decoded.into()),
                         }
+                    }))
+                };
 
                 results.push((s.name(), positions));
             }
@@ -430,7 +451,11 @@ impl Core {
     ///  * `id`:
     ///     Identifier to use to define the search volume.
     ///
-    pub fn get_by_label<S>(&self, parameters: &CoreQueryParameters, id: S) -> ResultSet
+    pub fn get_by_label<'d, S>(
+        &'d self,
+        parameters: &'d CoreQueryParameters,
+        id: S,
+    ) -> ResultSet<'d>
     where
         S: Into<String>,
     {
@@ -454,7 +479,7 @@ impl Core {
             let search_volume = self
                 .space_db
                 .iter()
-                .filter_map(|s| {
+                .filter_map(move |s| {
                     match db.space(s.name()) {
                         Err(_) => None,
                         Ok(from) => match s.get_by_id(offset, parameters) {
@@ -475,42 +500,40 @@ impl Core {
                         },
                     }
                 })
-                .flat_map(|v| v);
-
-            let search_volume = if let Some(view) = view_port {
-                search_volume
-                    .filter(|p| view.contains(p))
-                    .collect::<Vec<_>>()
-            } else {
-                search_volume.collect::<Vec<_>>()
-            };
+                .flatten();
 
             // Select based on the volume, and filter out the label position themselves.
             for s in &self.space_db {
                 let to = db.space(s.name())?;
-                let mut p = vec![];
+
+                let search_volume: IterPositions = if let Some(view) = view_port.clone() {
+                    Box::new(search_volume.clone().filter(move |p| view.contains(p)))
+                } else {
+                    Box::new(search_volume.clone())
+                };
 
                 // Convert the search Volume into the target space.
-                for position in &search_volume {
-                    let position = Space::change_base(position, Space::universe(), to)?;
-                    p.push(position);
+                let p = search_volume.filter_map(move |position| {
+                    match Space::change_base(&position, Space::universe(), to) {
+                        Err(_) => None,
+                        Ok(position) => Some(position),
                     }
+                });
 
-                let mut r = s
-                    .get_by_positions(&p, parameters)?
-                    .into_iter()
-                    .filter_map(|(position, fields)| {
+                let r = s
+                    .get_by_positions(p, parameters)?
+                    .filter_map(move |(position, fields)| {
                         if fields.value() == offset {
                             None
                         } else {
                             Some((position, &self.properties[fields.value()]))
                         }
-                    })
-                    .collect::<Vec<_>>();
+                    });
 
-                Self::decode_positions(r.as_mut_slice(), to, db, output_space)?;
-
-                results.push((s.name(), r));
+                results.push((
+                    s.name(),
+                    Self::decode_positions(Box::new(r), to, db, output_space)?,
+                ));
             }
         }
 

src/database/mod.rs

@@ -14,13 +14,20 @@ pub use db_core::Properties;
 use space::Position;
 use space::Space;
 
+/// TODO doc
+pub type IterPositions<'i> = Box<dyn Iterator<Item = Position> + 'i>;
+/// TODO doc
+pub type IterObjects<'i> = Box<dyn Iterator<Item = (Position, &'i Properties)> + 'i>;
+/// TODO doc
+pub type IterObjectsBySpaces<'i> = Vec<(&'i String, IterObjects<'i>)>;
+
 /// Selected tuples matching a query.
 ///
 /// This is either:
 ///  * `Err` with a reason stored as a `String`
 ///  * `Ok`, with a vector of tuples defined as:
 ///        `(Space Name, [(Position, Properties)])`
-pub type ResultSet<'r> = Result<Vec<(&'r String, Vec<(Position, &'r Properties)>)>, String>;
+pub type ResultSet<'r> = Result<IterObjectsBySpaces<'r>, String>;
 
 type ReferenceSpaceIndex = ironsea_index_hashmap::Index<Space, String>;
 type CoreIndex = ironsea_index_hashmap::Index<Core, String>;
@@ -109,7 +116,7 @@ impl DataBase {
                 list.len()
             ))
         } else {
-            Ok(&list[0])
+            Ok(list[0])
         }
     }
 
@@ -128,7 +135,10 @@ impl DataBase {
         if name == space::Space::universe().name() {
             Ok(space::Space::universe())
         } else {
-            let r = self.reference_spaces.find(&name.to_string());
+            let r = self
+                .reference_spaces
+                .find(&name.to_string())
+                .collect::<Vec<_>>();
 
             Self::check_exactly_one(&r, "spaces", name)
         }
@@ -146,7 +156,7 @@ impl DataBase {
     ///  * `name`:
     ///      The name of the dataset (core) to search for.
     pub fn core(&self, name: &str) -> Result<&Core, String> {
-        let r = self.cores.find(&name.to_string());
+        let r = self.cores.find(&name.to_string()).collect::<Vec<_>>();
 
         Self::check_exactly_one(&r, "cores", name)
     }

src/database/space/coordinate.rs

@@ -206,10 +206,10 @@ impl From<u64> for Coordinate {
         // Slight syntax hack, as exclusive ranges are not yet available.
         // cf: https://github.com/rust-lang/rust/issues/37854
         match v {
-            _ if v <= u64::from(std::u8::MAX) => Coordinate::CoordinateU8(v as u8),
-            _ if v <= u64::from(std::u16::MAX) => Coordinate::CoordinateU16(v as u16),
-            _ if v <= u64::from(std::u32::MAX) => Coordinate::CoordinateU32(v as u32),
-            _ => Coordinate::CoordinateU64(v as u64),
+            _ if v <= u64::from(u8::MAX) => Coordinate::CoordinateU8(v as u8),
+            _ if v <= u64::from(u16::MAX) => Coordinate::CoordinateU16(v as u16),
+            _ if v <= u64::from(u32::MAX) => Coordinate::CoordinateU32(v as u32),
+            _ => Coordinate::CoordinateU64(v),
             /*_ => {
                 panic!("Out of range {} > {}", v, std::u64::MAX);
             } */

src/database/space/coordinate_system.rs

@@ -84,8 +84,8 @@ impl CoordinateSystem {
         match self {
             CoordinateSystem::Universe { .. } => {
                 for _ in 0..self.dimensions() {
-                    low.push(std::f64::MIN);
-                    high.push(std::f64::MAX);
+                    low.push(f64::MIN);
+                    high.push(f64::MAX);
                 }
             }
             CoordinateSystem::AffineSystem { axes, .. } => {

src/database/space/position.rs

@@ -19,7 +19,7 @@ use serde::Serialize;
 use super::coordinate::Coordinate;
 
 /// Store a position as efficiently as possible in terms of space.
-#[derive(Clone, Debug, Deserialize, Eq, Hash, Ord, PartialEq, Serialize)]
+#[derive(Clone, Debug, Deserialize, Eq, Hash, PartialEq, Serialize)]
 pub enum Position {
     /// 1 dimension positions.
     Position1(Coordinate),
@@ -60,7 +60,8 @@ impl Position {
     /// Compute `||self||`.
     pub fn norm(&self) -> f64 {
         if let Position::Position1(coordinates) = self {
-            // the square root of a single number to the square is its positive value, so ensure it is.
+            // the square root of a single number to the square is its
+            // positive value, so ensure it is.
             coordinates.f64().abs()
         } else {
             let point: Vec<&Coordinate> = self.into();
@@ -127,6 +128,12 @@ impl Display for Position {
     }
 }
 
+impl Ord for Position {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.partial_cmp(other).unwrap()
+    }
+}
+
 impl PartialOrd for Position {
     fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
         // Let's restrict for now to same-length vectors.
@@ -143,7 +150,7 @@ impl PartialOrd for Position {
             return None;
         }
 
-        let ordering = ordering.drain().filter_map(|v| v).collect::<Vec<_>>();
+        let ordering = ordering.drain().flatten().collect::<Vec<_>>();
         match ordering.len() {
             3 => None,
             2 => {
@@ -356,14 +363,14 @@ impl<'s> From<&'s Position> for Vec<&'s Coordinate> {
     fn from(position: &'s Position) -> Self {
         match position {
             Position::Position1(coordinate) => vec![coordinate],
-            Position::Position2(coordinates) => coordinates.iter().map(|c| c).collect(),
-            Position::Position3(coordinates) => coordinates.iter().map(|c| c).collect(),
-            Position::Position4(coordinates) => coordinates.iter().map(|c| c).collect(),
-            Position::Position5(coordinates) => coordinates.iter().map(|c| c).collect(),
-            Position::Position6(coordinates) => coordinates.iter().map(|c| c).collect(),
-            Position::Position7(coordinates) => coordinates.iter().map(|c| c).collect(),
-            Position::Position8(coordinates) => coordinates.iter().map(|c| c).collect(),
-            Position::PositionN(coordinates) => coordinates.iter().map(|c| c).collect(),
+            Position::Position2(coordinates) => coordinates.iter().collect(),
+            Position::Position3(coordinates) => coordinates.iter().collect(),
+            Position::Position4(coordinates) => coordinates.iter().collect(),
+            Position::Position5(coordinates) => coordinates.iter().collect(),
+            Position::Position6(coordinates) => coordinates.iter().collect(),
+            Position::Position7(coordinates) => coordinates.iter().collect(),
+            Position::Position8(coordinates) => coordinates.iter().collect(),
+            Position::PositionN(coordinates) => coordinates.iter().collect(),
         }
     }
 }

src/database/space/shape.rs

@@ -39,7 +39,7 @@ impl Shape {
                 //FIXME: Is the length properly dealt with? How do we process this for space conversions?
                 let mut r = Vec::with_capacity(center.dimensions());
                 for _ in 0..center.dimensions() {
-                    r.push(radius.clone());
+                    r.push(*radius);
                 }
                 let r = r.into();
                 let r = from.absolute_position(&r)?;
@@ -276,7 +276,7 @@ impl Shape {
     /// Compute the volume.
     pub fn volume(&self) -> f64 {
         match self {
-            Shape::Point(_) => std::f64::EPSILON, // Smallest non-zero volume possible
+            Shape::Point(_) => f64::EPSILON, // Smallest non-zero volume possible
             Shape::BoundingBox(low, high) => {
                 let mut volume = 1.0;
 

src/database/space_db.rs

@@ -1,6 +1,7 @@
 use std::cmp::Ordering;
 use std::collections::hash_map::DefaultHasher;
 use std::collections::HashMap;
+use std::convert::TryInto;
 use std::hash::Hash;
 use std::hash::Hasher;
 
@@ -15,6 +16,7 @@ use super::space_index::SpaceIndex;
 use super::space_index::SpaceSetIndex;
 use super::space_index::SpaceSetObject;
 use super::CoreQueryParameters;
+use super::IterPositions;
 
 #[derive(Clone, Debug, Deserialize, Serialize)]
 pub struct SpaceDB {
@@ -59,8 +61,7 @@ impl SpaceDB {
             }
 
             // Apply fixed scales
-            let mut count = 0;
-            for power in &powers {
+            for (count, power) in powers.iter().enumerate() {
                 space_objects = space_objects
                     .into_iter()
                     .map(|mut o| {
@@ -79,8 +80,7 @@ impl SpaceDB {
                     .collect();
 
                 // Make sure we do not shift more position than available
-                let shift = if count >= 31 { 31 } else { count };
-                count += 1;
+                let shift: u32 = if count >= 31 { 31 } else { count.try_into().unwrap() };
                 indices.push((
                     SpaceSetIndex::new(space_objects.iter(), DIMENSIONS, CELL_BITS),
                     vec![power.0, power.0, power.0],
@@ -279,11 +279,11 @@ impl SpaceDB {
 
     // Search by Id, a.k.a values
     // The results are in encoded space coordinates.
-    pub fn get_by_id(
-        &self,
+    pub fn get_by_id<'s>(
+        &'s self,
         id: usize,
         parameters: &CoreQueryParameters,
-    ) -> Result<Vec<Position>, String> {
+    ) -> Result<IterPositions<'s>, String> {
         // Is that ID referenced in the current space?
         let index = self.resolution(parameters);
 
@@ -292,15 +292,20 @@ impl SpaceDB {
         let view_port = parameters.view_port(space);
 
         // Select the objects
-        let objects = self.resolutions[index].find_by_value(&SpaceFields::new(self.name(), id));
+        // FIXME: How to return an iterator instead of instantiating all
+        //        the points here? Needed because of &SpaceFields.
+        let objects = self.resolutions[index]
+            .find_by_value(&SpaceFields::new(self.name(), id))
+            .collect::<Vec<_>>();
 
-        let results = if let Some(view_port) = view_port {
+        let results: IterPositions<'s> = if let Some(view_port) = view_port {
+            Box::new(
                 objects
                     .into_iter()
-                .filter(|position| view_port.contains(position))
-                .collect::<Vec<_>>()
+                    .filter(move |position| view_port.contains(position)),
+            )
         } else {
-            objects
+            Box::new(objects.into_iter())
         };
 
         Ok(results)
@@ -308,11 +313,11 @@ impl SpaceDB {
 
     // Search by positions defining a volume.
     // The position is expressed in encoded space coordinates, and results are in encoded space coordinates.
-    pub fn get_by_positions(
-        &self,
-        positions: &[Position],
+    pub fn get_by_positions<'s>(
+        &'s self,
+        positions: impl Iterator<Item = Position> + 's,
         parameters: &CoreQueryParameters,
-    ) -> Result<Vec<(Position, &SpaceFields)>, String> {
+    ) -> Result<Box<dyn Iterator<Item = (Position, &SpaceFields)> + 's>, String> {
         let index = self.resolution(parameters);
 
         // FIXME: Should I do it here, or add the assumption this is a clean list?
@@ -321,17 +326,13 @@ impl SpaceDB {
         //let view_port = parameters.view_port(space);
 
         // Select the objects
-        let results = positions
-            .iter()
-            .flat_map(|position| {
+        let results = positions.flat_map(move |position| {
             self.resolutions[index]
-                    .find(position)
-                    .into_iter()
+                .find(&position)
                 .map(move |fields| (position.clone(), fields))
-            })
-            .collect();
+        });
 
-        Ok(results)
+        Ok(Box::new(results))
     }
 
     // Search by Shape defining a volume:
@@ -340,11 +341,11 @@ impl SpaceDB {
     // * Point (Specific position)
 
     // The Shape is expressed in encoded space coordinates, and results are in encoded space coordinates.
-    pub fn get_by_shape(
-        &self,
-        shape: &Shape,
+    pub fn get_by_shape<'s>(
+        &'s self,
+        shape: Shape,
         parameters: &CoreQueryParameters,
-    ) -> Result<Vec<(Position, &SpaceFields)>, String> {
+    ) -> Result<Box<dyn Iterator<Item = (Position, &SpaceFields)> + 's>, String> {
         let index = self.resolution(parameters);
 
         // Convert the view port to the encoded space coordinates
@@ -352,7 +353,7 @@ impl SpaceDB {
         let view_port = parameters.view_port(space);
 
         // Select the objects
-        let results = self.resolutions[index].find_by_shape(&shape, &view_port)?;
+        let results = self.resolutions[index].find_by_shape(shape, &view_port)?;
 
         Ok(results)
     }

src/database/space_index.rs

@@ -7,6 +7,7 @@ use serde::Serialize;
 use super::space::Coordinate;
 use super::space::Position;
 use super::space::Shape;
+use super::IterPositions;
 
 #[derive(Clone, Debug, Hash)]
 pub struct SpaceSetObject {
@@ -125,59 +126,63 @@ impl SpaceIndex {
     }
 
     // Inputs and Results are expressed in encoded space coordinates.
-    pub fn find(&self, key: &Position) -> Vec<&SpaceFields> {
+    pub fn find<'s>(&'s self, key: &Position) -> Box<dyn Iterator<Item = &SpaceFields> + 's> {
         self.index.find(key)
     }
 
     // Inputs and Results are expressed in encoded space coordinates.
-    fn find_range(&self, start: &Position, end: &Position) -> Vec<(Position, &SpaceFields)> {
+    fn find_range<'s>(
+        &'s self,
+        start: &Position,
+        end: &Position,
+    ) -> Box<dyn Iterator<Item = (Position, &SpaceFields)> + 's> {
         self.index.find_range(start, end)
     }
 
     // Inputs and Results are expressed in encoded space coordinates.
-    pub fn find_by_value(&self, id: &SpaceFields) -> Vec<Position> {
+    pub fn find_by_value<'s>(&'s self, id: &'s SpaceFields) -> IterPositions<'s> {
         self.index.find_by_value(id)
     }
 
     // Inputs and Results are also in encoded space coordinates.
-    pub fn find_by_shape(
-        &self,
-        shape: &Shape,
+    pub fn find_by_shape<'s>(
+        &'s self,
+        shape: Shape,
         view_port: &Option<Shape>,
-    ) -> Result<Vec<(Position, &SpaceFields)>, String> {
+    ) -> Result<Box<dyn Iterator<Item = (Position, &SpaceFields)> + 's>, String> {
         match shape {
             Shape::Point(position) => {
                 if let Some(mbb) = view_port {
-                    if !mbb.contains(position) {
+                    if !mbb.contains(&position) {
                         return Err(format!(
                             "View port '{:?}' does not contain '{:?}'",
                             mbb, position
                         ));
                     }
                 }
-                Ok(self
-                    .find(position)
-                    .into_iter()
-                    .map(|fields| (position.clone(), fields))
-                    .collect())
+                Ok(Box::new(
+                    self.find(&position)
+                        .map(move |fields| (position.clone(), fields)),
+                ))
             }
             Shape::BoundingBox(bl, bh) => {
                 if let Some(mbb) = view_port {
                     match mbb {
                         Shape::BoundingBox(vl, vh) => {
                             // Compute the intersection of the two boxes.
-                            let lower = bl.max(vl);
-                            let higher = bh.min(vh);
+                            let lower = (&bl).max(vl);
+                            let higher = (&bh).min(vh);
                             if higher < lower {
                                 Err(format!(
                                     "View port '{:?}' does not intersect '{:?}'",
-                                    mbb, shape
+                                    mbb,
+                                    Shape::BoundingBox(bl.clone(), bh.clone())
                                 ))
                             } else {
                                 trace!(
                                     "mbb {:?} shape {:?} lower {:?} higher {:?}",
                                     mbb,
-                                    shape,
+                                    Shape::BoundingBox(bl.clone(), bh.clone()),
                                     lower,
                                     higher
                                 );
@@ -187,11 +192,11 @@ impl SpaceIndex {
                         _ => Err(format!("Invalid view port shape '{:?}'", mbb)),
                     }
                 } else {
-                    Ok(self.find_range(bl, bh))
+                    Ok(self.find_range(&bl, &bh))
                 }
             }
             Shape::HyperSphere(center, radius) => {
-                let (bl, bh) = &shape.get_mbb();
+                let (bl, bh) = Shape::HyperSphere(center.clone(), radius).get_mbb();
                 let lower;
                 let higher;
 
@@ -199,26 +204,24 @@ impl SpaceIndex {
                     match mbb {
                         Shape::BoundingBox(vl, vh) => {
                             // Compute the intersection of the two boxes.
-                            lower = bl.max(vl);
-                            higher = bh.min(vh);
+                            lower = (&bl).max(vl);
+                            higher = (&bh).min(vh);
                         }
                         _ => return Err(format!("Invalid view port shape '{:?}'", mbb)),
                     }
                 } else {
-                    lower = bl;
-                    higher = bh;
+                    lower = &bl;
+                    higher = &bh;
                 }
 
                 // Filter out results using using a range query over the MBB,
                 // then add the condition of the radius as we are working within
                 // a sphere.
                 let results = self
-                    .find_range(&lower, &higher)
-                    .into_iter()
-                    .filter(|(position, _)| (position - center).norm() <= radius.f64())
-                    .collect();
+                    .find_range(lower, higher)
+                    .filter(move |(position, _)| (position - &center).norm() <= radius.f64());
 
-                Ok(results)
+                Ok(Box::new(results))
             }
         }
     }

src/storage/model.rs

@@ -68,9 +68,8 @@ pub mod v1 {
     use serde::Deserialize;
     use serde::Serialize;
 
-    use crate::database;
-    use database::space;
-
+    use super::database;
+    use super::space;
     use super::Point;
     use super::Properties;
 
@@ -87,7 +86,8 @@ pub mod v1 {
     /// Define a Shape, within a specific reference space.
     #[derive(Clone, Debug, Deserialize, Serialize)]
     pub struct Shape {
-        /// Type of the shape, which is used to interpret the list of `vertices`.
+        /// Type of the shape, which is used to interpret the list of
+        /// `vertices`.
         #[serde(rename = "type")]
         pub type_name: String,
 
@@ -99,8 +99,8 @@ pub mod v1 {
         pub vertices: Vec<Point>,
     }
 
-    /// Convert a list of properties grouped by space id, then positions to a
-    /// list of Spatial Objects for the rest API v1.
+    /// Convert a list of properties grouped by space id, then positions
+    /// to a list of Spatial Objects for the rest API v1.
     ///
     /// # Parameters
     ///
@@ -109,13 +109,14 @@ pub mod v1 {
     pub fn to_spatial_objects(
         list: Vec<(&String, Vec<(space::Position, &database::Properties)>)>,
     ) -> Vec<SpatialObject> {
-        // Filter per Properties, in order to regroup by it, then build a single SpatialObject per Properties.
+        // Filter per Properties, in order to regroup by it, then build
+        // a single SpatialObject per Properties.
         let mut hashmap = HashMap::new();
         for (space, v) in list {
             for (position, properties) in v {
                 hashmap
                     .entry(properties)
-                    .or_insert_with(|| vec![])
+                    .or_insert_with(Vec::new)
                     .push((space, position));
             }
         }
@@ -150,9 +151,8 @@ pub mod v2 {
     use serde::Deserialize;
     use serde::Serialize;
 
-    use crate::database;
-    use database::space;
-
+    use super::database;
+    use super::space;
     use super::Point;
     use super::Properties;
 
@@ -208,46 +208,88 @@ pub mod v2 {
         HyperSpheres(Vec<(Point, f64)>),
     }
 
-    /// Convert a list of properties grouped by space id, then positions to a
-    /// list of Spatial Objects for the rest API v2.
+    /// Convert a list of space id grouped by properties, then positions
+    /// to a list of Spatial Objects for the rest API v2.
+    ///
+    /// # Parameters
+    ///
+    ///  * `list`:
+    ///      A list of (`&Properties`, [ ( **Space Id**, [ *Spatial position* ] ) ]) tuples.
+    #[allow(clippy::type_complexity)]
+    // Type alias cannot be used as Traits, so we can't use the alias to add the lifetime specifications.
+    pub fn from_spaces_by_properties<'o>(
+        objects: Box<
+            (dyn Iterator<
+                Item=(
+                    &'o database::Properties,
+                    Vec<(&'o String, Box<dyn Iterator<Item=space::Position> + 'o>)>,
+                ),
+            > + 'o),
+        >,
+    ) -> impl Iterator<Item=SpatialObject> + 'o {
+        objects.map(|(property, positions_by_spaces)| {
+            let volumes = positions_by_spaces
+                .into_iter()
+                .map(|(space, positions)| {
+                    // We are not using vec![] as we now beforehand we
+                    // will have only one element in the vector, so we
+                    // optimise for space by allocating it as such.
+                    let shapes = vec![
+                        Shape::Points(positions.map(|position|
+                            position.into()).collect::<Vec<_>>())
+                    ];
+
+                    Volume {
+                        space: space.clone(),
+                        shapes,
+                    }
+                })
+                .collect();
+
+            SpatialObject {
+                properties: (&property).into(),
+                volumes,
+            }
+        })
+    }
+
+    /// Convert a list of properties grouped by space id, then positions
+    /// to a list of Spatial Objects for the rest API v2.
     ///
     /// # Parameters
     ///
     ///  * `list`:
     ///      A list of (**Space Id**, [ ( *Spatial position*, `&Properties` ) ]) tuples.
-    pub fn to_spatial_objects(
-        list: Vec<(&String, Vec<(space::Position, &database::Properties)>)>,
-    ) -> Vec<SpatialObject> {
-        // Filter per Properties, in order to regroup by it, then build a single SpatialObject per Properties.
+    pub fn from_properties_by_spaces(
+        objects: database::IterObjectsBySpaces<'_>,
+    ) -> impl Iterator<Item=SpatialObject> + '_ {
+        // Filter per Properties, in order to regroup by it, then build
+        // a single SpatialObject per Properties.
         let mut hashmap = HashMap::new();
-        for (space, v) in list {
+        for (space, v) in objects {
             for (position, properties) in v {
                 hashmap
                     .entry(properties)
                     .or_insert_with(HashMap::new)
                     .entry(space)
-                    .or_insert_with(|| vec![])
-                    .push(position.into());
+                    .or_insert_with(Vec::new)
+                    .push(position);
             }
         }
 
-        let mut results = vec![];
-        for (properties, v) in hashmap.iter_mut() {
-            let volumes = v
-                .drain()
-                .map(|(space, positions)| Volume {
-                    space: space.clone(),
-                    shapes: vec![Shape::Points(positions)],
+        let results = Box::new(hashmap.into_iter().map(|(property, hm)| {
+            let positions = hm
+                .into_iter()
+                .map(|(space, positions)| {
+                    let positions: database::IterPositions = Box::new(positions.into_iter());
+                    (space, positions)
                 })
-                .collect();
+                .collect::<Vec<_>>();
 
-            results.push(SpatialObject {
-                properties: properties.into(),
-                volumes,
-            });
-        }
+            (property, positions)
+        }));
 
-        results
+        from_spaces_by_properties(results)
     }
 }
 
@@ -410,6 +452,9 @@ pub fn build_index(
         }
 
         properties.append(&mut properties_hm.drain().map(|(_, v)| v).collect::<Vec<_>>());
+
+        // We we use sort_by_key, we get borrow checker errors.
+        #[allow(clippy::unnecessary_sort_by)]
         properties.sort_unstable_by(|a, b| a.id().cmp(b.id()));
 
         space_set_objects.iter_mut().for_each(|object| {

src/storage/xyz.rs

@@ -181,7 +181,7 @@ fn convert(string: &str) -> Result<Vec<SpatialObject>, Error> {
                     let (x, y, z) = (x * 0.039_062_5, y * 0.039_062_5, z * 0.039_062_5);
 
                     oids.entry(oid)
-                        .or_insert_with(|| vec![])
+                        .or_insert_with(Vec::new)
                         .push(vec![x, y, z]);
                 }
             }