New node: 'Index'

Author: Keavon

node-graph/gcore/src/graphic_element.rs

@@ -551,3 +551,53 @@ impl From<GraphicGroupTable> for GraphicElement {
 pub trait ToGraphicElement {
 	fn to_graphic_element(&self) -> GraphicElement;
 }
+
+/// Returns the value at the specified index in the collection.
+/// If that index has no value, the type's default value is returned.
+#[node_macro::node(category("General"))]
+fn index<T: AtIndex + Clone + Default>(
+	_: impl Ctx,
+	/// The collection of data, such as a list or table.
+	#[implementations(
+		Vec<Color>,
+		Vec<Option<Color>>,
+		Vec<f64>, Vec<u64>,
+		Vec<DVec2>,
+		VectorDataTable,
+		RasterDataTable<CPU>,
+		GraphicGroupTable,
+	)]
+	collection: T,
+	/// The index of the item to retrieve, starting from 0 for the first item.
+	index: u32,
+) -> T::Output
+where
+	T::Output: Clone + Default,
+{
+	collection.at_index(index as usize).unwrap_or_default()
+}
+
+pub trait AtIndex {
+	type Output;
+	fn at_index(&self, index: usize) -> Option<Self::Output>;
+}
+impl<T: Clone> AtIndex for Vec<T> {
+	type Output = T;
+
+	fn at_index(&self, index: usize) -> Option<Self::Output> {
+		self.get(index).cloned()
+	}
+}
+impl<T: Clone> AtIndex for Instances<T> {
+	type Output = Instances<T>;
+
+	fn at_index(&self, index: usize) -> Option<Self::Output> {
+		let mut result_table = Self::default();
+		if let Some(row) = self.instance_ref_iter().nth(index) {
+			result_table.push(row.to_instance_cloned());
+			Some(result_table)
+		} else {
+			None
+		}
+	}
+}