Add Active Tool Router (#58)

* Add Active Tool Router

* Remove commented out import

core/editor/src/macros.rs

@@ -0,0 +1,49 @@
+/// Counts args in the macro invocation by adding `+ 1` for every arg.
+///
+/// # Example
+///
+/// ```ignore
+/// let x = count_args!(("example1"), (10), (25));
+/// assert_eq!(x, 3);
+/// ```
+/// expands to
+/// ```ignore
+/// let x = 0 + 1 + 1 + 1;
+/// assert_eq!(x, 3);
+/// ```
+macro_rules! count_args {
+	(@one $($t:tt)*) => { 1 };
+	($(($($x:tt)*)),*$(,)?) => {
+		0 $(+ count_args!(@one $($x)*))*
+	};
+}
+
+/// Generates a [`std::collections::HashMap`] for `ToolState`'s `tools` variable.
+///
+/// # Example
+///
+/// ```ignore
+/// let tools = gen_tools_hash_map! {
+/// 	Select => select::Select,
+/// 	Crop => crop::Crop,
+/// };
+/// ```
+/// expands to
+/// ```ignore
+/// let tools = {
+/// 	let mut hash_map: std::collections::HashMap<crate::tools::ToolType, Box<dyn crate::tools::Tool>> = std::collections::HashMap::with_capacity(count_args!(/* Macro args */));
+///
+/// 	hash_map.insert(crate::tools::ToolType::Select, Box::new(select::Select::default()));
+/// 	hash_map.insert(crate::tools::ToolType::Crop, Box::new(crop::Crop::default()));
+///
+/// 	hash_map
+/// };
+/// ```
+macro_rules! gen_tools_hash_map {
+	($($enum_variant:ident => $struct_path:ty),* $(,)?) => {{
+		let mut hash_map: ::std::collections::HashMap<$crate::tools::ToolType, ::std::boxed::Box<dyn $crate::tools::Tool>> = ::std::collections::HashMap::with_capacity(count_args!($(($enum_variant)),*));
+		$(hash_map.insert($crate::tools::ToolType::$enum_variant, ::std::boxed::Box::new(<$struct_path>::default()));)*
+
+		hash_map
+	}};
+}