Basic knowledge of self and regions

src/board.rs

@@ -0,0 +1,132 @@
+use crate::cell::{Cell, CellValue};
+use std::collections::HashSet;
+
+pub struct Board {
+    cells: Vec<Vec<Cell>>,
+    regions: Vec<Region>,
+}
+
+impl Board {
+    pub fn new() -> Board {
+        let mut rows = Vec::with_capacity(9);
+        for _ in 0..9 {
+            let mut col = Vec::with_capacity(9);
+            for _ in 0..9 {
+                col.push(Cell::default());
+            }
+            rows.push(col);
+        }
+        let mut regions = Vec::with_capacity(9);
+        for x in 0..3 {
+            for y in 0..3 {
+                regions.push(Region::new(&Point(x, y)));
+            }
+        }
+        let board = Board {
+            cells: rows,
+            regions
+        };
+        board
+    }
+
+    pub fn value(&self, point: &Point) -> Option<CellValue> {
+        self.cells[point.0][point.1].value()
+    }
+
+    pub fn set_value(&mut self, point: &Point, value: CellValue) {
+        self.cells[point.0][point.1].set_value(value);
+        self.update_row(point.0, value);
+        self.update_column(point.1, value);
+        self.update_region(point, value);
+    }
+
+    pub fn update_row(&mut self, x: usize, value: CellValue) {
+        for i in self.cells[x].iter_mut() {
+            i.remove_candidate(value);
+        }
+    }
+
+    pub fn update_column(&mut self, y: usize, value: CellValue) {
+        for i in self.cells.iter_mut() {
+            (*i)[y].remove_candidate(value);
+        }
+    }
+
+    pub fn update_region(&mut self, point: &Point, value: CellValue) {
+        for i in self.regions.iter_mut() {
+            if i.includes(point) {
+                for pt in i.iter_mut() {
+                    self.cells[pt.0][pt.1].remove_candidate(value);
+                }
+            }
+        }
+    }
+
+    pub fn candidates(&self, point: &Point) -> HashSet<CellValue> {
+        self.cells[point.0][point.1].candidates()
+    }
+}
+
+#[derive(PartialEq, Debug)]
+pub struct Point(usize, usize);
+
+pub struct Region {
+    points: Vec<Point>,
+}
+
+impl Region {
+    pub fn new(start: &Point)-> Region {
+        let mut points = Vec::with_capacity(9);
+        for x in start.0..(start.0 + 3) {
+            for y in start.1..(start.1 + 3) {
+                points.push(Point(x, y));
+            }
+        }
+        Region {
+            points,
+        }
+    }
+    
+    pub fn iter(&self) -> std::slice::Iter<Point> {
+        self.points.iter()
+    }
+    
+    pub fn includes(&self, point: &Point) -> bool {
+        self.points.contains(point)
+    }
+    
+    pub fn iter_mut(&mut self) -> std::slice::IterMut<Point> {
+        self.points.iter_mut()
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use assertables::{assert_contains, assert_not_contains};
+
+    use super::*;
+
+    #[test]
+    fn has_none_values() {
+        let board = Board::new();
+        assert!(board.value(&Point(0, 0)).is_none());
+    }
+
+    #[test]
+    fn set_value_updates_cell() {
+        let mut board = Board::new();
+        board.set_value(&Point(0, 0), CellValue::One);
+        let val = board.value(&Point(0, 0)).unwrap();
+        assert_eq!(val, CellValue::One);
+
+        // Same column
+        assert_not_contains!(board.candidates(&Point(0, 1)), &CellValue::One);
+        // Same row
+        assert_not_contains!(board.candidates(&Point(1, 0)), &CellValue::One);
+        // Same sub-structure
+        assert_not_contains!(board.candidates(&Point(1, 1)), &CellValue::One);
+
+        // Different row
+        assert_contains!(board.candidates(&Point(8, 8)), &CellValue::One);
+    }
+}

src/cell.rs

@@ -0,0 +1,97 @@
+use std::collections::HashSet;
+
+#[derive(Clone, Debug, Copy, Hash, Eq, PartialEq)]
+pub enum CellValue {
+    One,
+    Two,
+    Three,
+    Four,
+    Five,
+    Six,
+    Seven,
+    Eight,
+    Nine,
+}
+
+pub struct Cell {
+    value: Option<CellValue>,
+    candidates: HashSet<CellValue>,
+}
+
+impl Cell {
+    pub fn value(&self) -> Option<CellValue> {
+        self.value
+    }
+
+    pub fn set_value(&mut self, value: CellValue) {
+        self.value = Some(value);
+    }
+
+    pub fn candidates(&self) -> HashSet<CellValue> {
+        self.candidates.clone()
+    }
+
+    pub fn remove_candidate(&mut self, value: CellValue) {
+        self.candidates.remove(&value);
+    }
+}
+
+impl Default for Cell {
+    fn default() -> Cell {
+        let mut candidates = HashSet::new();
+        candidates.insert(CellValue::One);
+        candidates.insert(CellValue::Two);
+        candidates.insert(CellValue::Three);
+        candidates.insert(CellValue::Four);
+        candidates.insert(CellValue::Five);
+        candidates.insert(CellValue::Six);
+        candidates.insert(CellValue::Seven);
+        candidates.insert(CellValue::Eight);
+        candidates.insert(CellValue::Nine);
+        Cell {
+            value: None,
+            candidates,
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use assertables::{assert_contains, assert_not_contains};
+
+    #[test]
+    fn inits_empty() {
+        let cell = Cell::default();
+        assert!(cell.value().is_none());
+    }
+
+    #[test]
+    fn has_all_candidates() {
+        let cell = Cell::default();
+        assert_contains!(cell.candidates(), &CellValue::One);
+        assert_contains!(cell.candidates(), &CellValue::Two);
+        assert_contains!(cell.candidates(), &CellValue::Three);
+        assert_contains!(cell.candidates(), &CellValue::Four);
+        assert_contains!(cell.candidates(), &CellValue::Five);
+        assert_contains!(cell.candidates(), &CellValue::Six);
+        assert_contains!(cell.candidates(), &CellValue::Seven);
+        assert_contains!(cell.candidates(), &CellValue::Eight);
+        assert_contains!(cell.candidates(), &CellValue::Nine);
+    }
+
+    #[test]
+    fn removed_candidate_is_gone() {
+        let mut cell = Cell::default();
+        cell.remove_candidate(CellValue::One);
+        assert_not_contains!(cell.candidates(), &CellValue::One);
+        assert_contains!(cell.candidates(), &CellValue::Two);
+        assert_contains!(cell.candidates(), &CellValue::Three);
+        assert_contains!(cell.candidates(), &CellValue::Four);
+        assert_contains!(cell.candidates(), &CellValue::Five);
+        assert_contains!(cell.candidates(), &CellValue::Six);
+        assert_contains!(cell.candidates(), &CellValue::Seven);
+        assert_contains!(cell.candidates(), &CellValue::Eight);
+        assert_contains!(cell.candidates(), &CellValue::Nine);
+    }
+}

src/lib.rs

@@ -1,62 +1,2 @@
-#[derive(Clone, Debug, Copy)]
-pub enum CellValue {
-    One,
-    Two,
-    Three,
-    Four,
-    Five,
-    Six,
-    Seven,
-    Eight,
-    Nine,
-}
-
-pub struct Cell {
-    value: Option<CellValue>,
-    candidates: Vec<CellValue>,
-}
-
-impl Default for Cell {
-    fn default() -> Cell {
-        Cell {
-            value: None,
-            candidates: vec![
-                CellValue::One,
-                CellValue::Two,
-                CellValue::Three,
-                CellValue::Four,
-                CellValue::Five,
-                CellValue::Six,
-                CellValue::Seven,
-                CellValue::Eight,
-                CellValue::Nine,
-            ],
-        }
-    }
-}
-
-#[derive(Default)]
-pub struct Board {
-    cells: [[Cell; 9]; 9],
-}
-
-impl Board {
-    fn value(self, x: usize, y: usize) -> Option<CellValue> {
-        self.cells[x][y].value
-    }
-}
-
-pub fn add(left: u64, right: u64) -> u64 {
-    left + right
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn it_works() {
-        let result = add(2, 2);
-        assert_eq!(result, 4);
-    }
-}
+pub mod cell;
+pub mod board;