de-cycle conduit_macros from conduit_core.

Signed-off-by: Jason Volk <jason@zemos.net>

src/macros/utils.rs

@@ -0,0 +1,25 @@
+#[must_use]
+pub(crate) fn camel_to_snake_string(s: &str) -> String {
+	let mut output = String::with_capacity(
+		s.chars()
+			.fold(s.len(), |a, ch| a.saturating_add(usize::from(ch.is_ascii_uppercase()))),
+	);
+
+	let mut state = false;
+	s.chars().for_each(|ch| {
+		let m = ch.is_ascii_uppercase();
+		let s = exchange(&mut state, !m);
+		if m && s {
+			output.push('_');
+		}
+		output.push(ch.to_ascii_lowercase());
+	});
+
+	output
+}
+
+pub(crate) fn exchange<T: Clone>(state: &mut T, source: T) -> T {
+	let ret = state.clone();
+	*state = source;
+	ret
+}