feat(pod): add PodOption, PodString, and PodVec collection types

crates/pina_pod_primitives/src/error.rs

@@ -0,0 +1,35 @@
+//! Error type for Pod collection operations.
+
+use core::fmt;
+
+/// Error type for collection operations.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum PodCollectionError {
+	/// Value exceeds capacity.
+	Overflow,
+	/// Invalid UTF-8 in string data.
+	InvalidUtf8,
+	/// Index out of bounds.
+	OutOfBounds,
+}
+
+impl fmt::Display for PodCollectionError {
+	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+		match self {
+			Self::Overflow => write!(f, "value exceeds capacity"),
+			Self::InvalidUtf8 => write!(f, "invalid UTF-8"),
+			Self::OutOfBounds => write!(f, "index out of bounds"),
+		}
+	}
+}
+
+/// Returns the maximum `N` value representable by a `PFX`-byte length prefix.
+pub(crate) const fn max_n_for_pfx(pfx: usize) -> usize {
+	match pfx {
+		1 => u8::MAX as usize,
+		2 => u16::MAX as usize,
+		4 => u32::MAX as usize,
+		8 => usize::MAX,
+		_ => 0,
+	}
+}