Add display trait to technique mask

Author: huangsam

rustoku-lib/src/core/techniques/mod.rs

@@ -2,6 +2,7 @@ use super::board::Board;
 use super::candidates::Candidates;
 use super::masks::Masks;
 use bitflags::bitflags;
+use std::fmt;
 
 mod hidden_pairs;
 mod hidden_singles;
@@ -44,6 +45,37 @@ bitflags! {
     }
 }
 
+impl fmt::Display for TechniqueMask {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if self.is_empty() {
+            return write!(f, "None");
+        }
+
+        let mut techniques = Vec::new();
+
+        if self.contains(TechniqueMask::NAKED_SINGLES) {
+            techniques.push("Naked Singles");
+        }
+        if self.contains(TechniqueMask::HIDDEN_SINGLES) {
+            techniques.push("Hidden Singles");
+        }
+        if self.contains(TechniqueMask::NAKED_PAIRS) {
+            techniques.push("Naked Pairs");
+        }
+        if self.contains(TechniqueMask::HIDDEN_PAIRS) {
+            techniques.push("Hidden Pairs");
+        }
+        if self.contains(TechniqueMask::LOCKED_CANDIDATES) {
+            techniques.push("Locked Candidates");
+        }
+        if self.contains(TechniqueMask::XWING) {
+            techniques.push("X-Wing");
+        }
+
+        write!(f, "{}", techniques.join(", "))
+    }
+}
+
 // Now the actual implementation of the techniques, these would operate on
 // references to Board, Masks, and CandidatesCache.
 pub struct TechniquePropagator<'a> {
@@ -143,3 +175,32 @@ pub trait TechniqueRule {
     /// Applies the technique to the given propagator.
     fn apply(&self, prop: &mut TechniquePropagator, path: &mut Vec<(usize, usize, u8)>) -> bool;
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_display_empty_mask() {
+        let mask = TechniqueMask::empty();
+        assert_eq!(format!("{}", mask), "None");
+    }
+
+    #[test]
+    fn test_display_single_technique() {
+        let mask = TechniqueMask::NAKED_SINGLES;
+        assert_eq!(format!("{}", mask), "Naked Singles");
+
+        let mask = TechniqueMask::XWING;
+        assert_eq!(format!("{}", mask), "X-Wing");
+    }
+
+    #[test]
+    fn test_display_multiple_techniques() {
+        let mask = TechniqueMask::EASY;
+        assert_eq!(format!("{}", mask), "Naked Singles, Hidden Singles");
+
+        let mask = TechniqueMask::NAKED_SINGLES | TechniqueMask::XWING | TechniqueMask::LOCKED_CANDIDATES;
+        assert_eq!(format!("{}", mask), "Naked Singles, Locked Candidates, X-Wing");
+    }
+}