Add docs to lib

wr_lib/src/lib.rs

@@ -2,27 +2,42 @@ use log::debug;
 
 use serde::{Deserialize, Serialize};
 
+/// All available operations of the calculator API
 #[derive(Debug, Deserialize)]
 enum CalcOp {
+    /// Add two numbers
     Add,
+    /// Substract two numbers
     Sub,
+    /// Multiply two numbers
     Mul,
+    /// Divide two numbers
     Div,
 }
 
+/// A request to the calculator API
 #[derive(Debug, Deserialize)]
 pub struct CalcReq {
+    /// Left-hand operand of the calculation
     a: i32,
+    /// Right-hand operand of the calculation
     b: i32,
+    /// The operation to calculate
     op: CalcOp,
 }
 
+/// Result of a calculation of the calculator API
 #[derive(Serialize)]
 pub struct CalcRes {
+    /// Result of the calculation
     res: i32,
 }
 
 impl CalcReq {
+    /// Perform the calculation
+    ///
+    /// Returns a [CalcRes] in case the calculation was successful, or
+    /// an error if it overflows or causes other arithmetic errors.
     pub fn calc(&self) -> Option<CalcRes> {
         debug!("Calculating: {:?}", self);