Add ability to compare/sort/merge items using a sortby config

crates/core/Cargo.toml

@@ -12,6 +12,7 @@ repository.workspace = true
 rust-version.workspace = true
 
 [features]
+stream = ["dep:futures", "dep:stream-kmerge"]
 std = []
 geo = ["dep:geo"]
 geoarrow = [
@@ -51,6 +52,8 @@ serde_json = { workspace = true, features = ["preserve_order"] }
 serde_urlencoded.workspace = true
 stac-derive = { version = "0.3.0", path = "../derive" }
 thiserror.workspace = true
+stream-kmerge = { version = "0.2.0", optional = true }
+futures = { workspace = true, optional = true }
 tracing.workspace = true
 url = { workspace = true, features = ["serde"] }
 wkb = { workspace = true, optional = true }

crates/core/src/item_collection.rs

@@ -56,6 +56,34 @@ pub struct ItemCollection {
     self_href: Option<String>,
 }
 
+impl ItemCollection {
+    /// Sorts the items in this collection.
+    ///
+    /// If a `config` is provided, it must be a valid JSON representation of a SortConfig.
+    /// If `None`, the default [`crate::sort::ItemComparator`] is used.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use stac::{Item, ItemCollection};
+    /// use serde_json::json;
+    ///
+    /// let mut ic = ItemCollection::from(vec![Item::new("b"), Item::new("a")]);
+    /// ic.sort(Some(json!({
+    ///     "sortby": [
+    ///         { "field": "id", "direction": "asc" }
+    ///     ]
+    /// }))).unwrap();
+    /// assert_eq!(ic.items[0].id, "a");
+    /// ```
+    pub fn sort(&mut self, config: Option<Value>) -> Result<()> {
+        use crate::sort::Sortable;
+        let items = std::mem::take(&mut self.items);
+        self.items = items.sort(config)?;
+        Ok(())
+    }
+}
+
 impl From<Vec<Item>> for ItemCollection {
     fn from(items: Vec<Item>) -> Self {
         ItemCollection {

crates/core/src/lib.rs

@@ -124,6 +124,8 @@ pub mod link;
 mod migrate;
 pub mod mime;
 mod ndjson;
+/// Sort STAC items.
+pub mod sort;
 mod statistics;
 mod value;
 mod version;
@@ -149,6 +151,7 @@ pub use json::{FromJson, ToJson};
 pub use link::{Link, Links};
 pub use migrate::Migrate;
 pub use ndjson::{FromNdjson, ToNdjson};
+pub use sort::Sortable;
 pub use statistics::Statistics;
 pub use value::Value;
 pub use version::Version;