# tile_repository.rs - source
Source of the Rust file `maplibre/src/io/tile_repository.rs`.
Keywords: rust, rustlang, rust-lang

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    //! Tile cache.

    use crate::coords::{Quadkey, WorldTileCoords};
    use crate::render::ShaderVertex;
    use crate::tessellation::{IndexDataType, OverAlignedVertexBuffer};
    use geozero::mvt::tile;
    use std::collections::{btree_map, BTreeMap, HashSet};

    /// A layer which is stored for future use.
    pub enum StoredLayer {
        UnavailableLayer {
            coords: WorldTileCoords,
            layer_name: String,
        },
        TessellatedLayer {
            coords: WorldTileCoords,
            buffer: OverAlignedVertexBuffer<ShaderVertex, IndexDataType>,
            /// Holds for each feature the count of indices.
            feature_indices: Vec<u32>,
            layer_data: tile::Layer,
        },
    }

    impl StoredLayer {
        pub fn get_coords(&self) -> WorldTileCoords {
            match self {
                StoredLayer::UnavailableLayer { coords, .. } => *coords,
                StoredLayer::TessellatedLayer { coords, .. } => *coords,
            }
        }

        pub fn layer_name(&self) -> &str {
            match self {
                StoredLayer::UnavailableLayer { layer_name, .. } => layer_name.as_str(),
                StoredLayer::TessellatedLayer { layer_data, .. } => &layer_data.name,
            }
        }
    }

    /// Stores multiple [StoredLayers](StoredLayer).
    pub struct StoredTile {
        layers: Vec<StoredLayer>,
    }

    impl StoredTile {
        pub fn new(first_layer: StoredLayer) -> Self {
            Self {
                layers: vec![first_layer],
            }
        }
    }

    /// Stores and provides access to a quad tree of cached tiles with world tile coords.
    #[derive(Default)]
    pub struct TileRepository {
        tree: BTreeMap<Quadkey, StoredTile>,
    }

    impl TileRepository {
        pub fn new() -> Self {
            Self {
                tree: BTreeMap::new(),
            }
        }

        /// Inserts a tessellated layer into the quad tree at its world tile coords.
        /// If the space is vacant, the tessellated layer is inserted into a new
        /// [crate::io::tile_repository::CachedTile].
        /// If the space is occupied, the tessellated layer is added to the current
        /// [crate::io::tile_repository::CachedTile].
        pub fn put_tessellated_layer(&mut self, layer: StoredLayer) {
            if let Some(entry) = layer
                .get_coords()
                .build_quad_key()
                .map(|key| self.tree.entry(key))
            {
                match entry {
                    btree_map::Entry::Vacant(entry) => {
                        entry.insert(StoredTile::new(layer));
                    }
                    btree_map::Entry::Occupied(mut entry) => {
                        entry.get_mut().layers.push(layer);
                    }
                }
            }
        }

        /// Returns the list of tessellated layers at the given world tile coords. None if tile is
        /// missing from the cache.
        pub fn iter_tessellated_layers_at(
            &self,
            coords: &WorldTileCoords,
        ) -> Option<impl Iterator<Item = &StoredLayer> + '_> {
            coords
                .build_quad_key()
                .and_then(|key| self.tree.get(&key))
                .map(|results| results.layers.iter())
        }

        /// Removes all the cached tessellate layers that are not contained within the given
        /// layers hashset.
        pub fn retain_missing_layer_names(
            &self,
            coords: &WorldTileCoords,
            layers: &mut HashSet<String>,
        ) {
            if let Some(cached_tile) = coords.build_quad_key().and_then(|key| self.tree.get(&key)) {
                let tessellated_set: HashSet<String> = cached_tile
                    .layers
                    .iter()
                    .map(|tessellated_layer| tessellated_layer.layer_name().to_string())
                    .collect();

                layers.retain(|layer| !tessellated_set.contains(layer));
            }
        }

        /// Checks if a layer is missing from the given layers set at the given coords.
        pub fn is_layers_missing(&self, coords: &WorldTileCoords, layers: &HashSet<String>) -> bool {
            if let Some(cached_tile) = coords.build_quad_key().and_then(|key| self.tree.get(&key)) {
                let tessellated_set: HashSet<&str> = cached_tile
                    .layers
                    .iter()
                    .map(|tessellated_layer| tessellated_layer.layer_name())
                    .collect();

                for layer in layers {
                    if !tessellated_set.contains(layer.as_str()) {
                        return true;
                    }
                }

                return false;
            }
            true
        }
    }