update interface for illegal positions

src/setup.rs

@@ -542,8 +542,8 @@ impl std::error::Error for ParseSetupError {}
 /// This is an illegal position that can't be represented with the [`Position`] type.
 #[derive(Debug)]
 pub struct IllegalPosition {
-    setup: Setup,
-    reasons: IllegalPositionReasons,
+    pub setup: Setup,
+    pub reasons: IllegalPositionReasons,
 }
 impl std::fmt::Display for IllegalPosition {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
@@ -556,30 +556,14 @@ impl std::fmt::Display for IllegalPosition {
                 f.write_char(',')?;
             }
             first = false;
-            write!(f, " {reason}")?;
+            f.write_char(' ')?;
+            f.write_str(reason.to_str())?;
         }
         Ok(())
     }
 }
 impl std::error::Error for IllegalPosition {}
 
-impl IllegalPosition {
-    /// Returns an iterator over the reasons why the position is rejected.
-    pub fn reasons(&self) -> IllegalPositionReasons {
-        self.reasons
-    }
-
-    /// Returns the [`Setup`] that failed validation.
-    pub fn as_setup(&self) -> &Setup {
-        &self.setup
-    }
-
-    /// Returns the [`Setup`] that failed validation.
-    pub fn into_setup(self) -> Setup {
-        self.setup
-    }
-}
-
 /// A set of [`IllegalPositionReason`]s.
 #[derive(Clone, Copy)]
 pub struct IllegalPositionReasons(u8);
@@ -650,9 +634,9 @@ pub enum IllegalPositionReason {
     ImpossibleEnPassantPin = 128,
 }
 
-impl std::fmt::Display for IllegalPositionReason {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.write_str(match self {
+impl IllegalPositionReason {
+    fn to_str(self) -> &'static str {
+        match self {
             Self::MissingKing => "missing king",
             Self::TooManyKings => "too many kings",
             Self::HangingKing => "hanging king",
@@ -661,6 +645,12 @@ impl std::fmt::Display for IllegalPositionReason {
             Self::InvalidEnPassant => "invalid en passant",
             Self::TooMuchMaterial => "too much material",
             Self::ImpossibleEnPassantPin => "illegal en passant",
-        })
+        }
+    }
+}
+
+impl std::fmt::Display for IllegalPositionReason {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(self.to_str())
     }
 }

tests/tests.rs

@@ -200,7 +200,7 @@ fn setup() {
                 .parse::<Setup>()
                 .unwrap()
                 .into_position()
-                .is_err_and(|e| e.reasons().contains(reason)),
+                .is_err_and(|e| e.reasons.contains(reason)),
             "{record} should be invalid because of {reason:?}",
         );
     }