[code] refactor, clippy, rustfmt

- added clippy lints and fixed the resulting issues
- moved build_possible_values_db() into the new() call
- extracted the skip_db functionality into their own functions

Cargo.toml

@@ -4,6 +4,11 @@ version = "0.1.0"
 authors = ["ddidderr <ddidderr@paul.network>"]
 edition = "2021"
 
+[lints.clippy]
+pedantic = { level = "warn", priority = -1 }
+todo = "warn"
+unwrap_used = "warn"
+
 [dependencies]
 
 [profile.release]

rustfmt.toml

@@ -0,0 +1,3 @@
+group_imports = "StdExternalCrate"
+imports_granularity = "Crate"
+imports_layout = "HorizontalVertical"

src/main.rs

@@ -4,10 +4,26 @@ const BLOCK_SIZE: usize = 3;
 const SIZE: usize = BLOCK_SIZE * BLOCK_SIZE;
 const NUM_FIELDS: usize = SIZE * SIZE;
 
+fn print_gray() {
+    print!("\x1b\x5b\x31\x3b\x33\x30\x6d");
+}
+
+fn print_green() {
+    print!("\x1b\x5b\x31\x3b\x33\x32\x6d");
+}
+
+fn print_neutral() {
+    print!("\x1b\x5b\x31\x3b\x30\x6d");
+}
+
+fn print_clear() {
+    print!("\x1b\x5b\x48\x1b\x5b\x32\x4a");
+}
+
 struct SField {
     field: Vec<u8>,
-    skipf: Vec<u8>,
+    skip_forward: Vec<u8>,
-    skipb: Vec<u8>,
+    skip_backward: Vec<u8>,
     pos: usize,
     possible_values: Vec<Vec<u8>>,
 }
@@ -27,6 +43,22 @@ impl SField {
             0,0,8,2,0,0,0,6,0,
         ];
 
+        let mut sudoku = SField {
+            field,
+            skip_forward: vec![0; NUM_FIELDS + 1],
+            skip_backward: vec![0; NUM_FIELDS + 1],
+            pos: 0,
+            possible_values: vec![vec![]; NUM_FIELDS],
+        };
+
+        sudoku.build_possible_values_db();
+
+        sudoku.build_skip_dbs();
+
+        sudoku
+    }
+
+    fn build_skip_dbs(&mut self) {
         fn find_fixed_streak_forward(mut idx: usize, field: &[u8]) -> u8 {
             let mut fixed_count = 1;
             idx += 1;
@@ -51,29 +83,21 @@ impl SField {
             fixed_count
         }
 
-        let mut skipf = vec![0; NUM_FIELDS + 1];
+        let fwd = &mut self.skip_forward;
-        for (idx, nr) in field.iter().enumerate() {
+        for (idx, nr) in self.field.iter().enumerate() {
             match nr {
-                0 => skipf[idx] = *nr,
+                0 => fwd[idx] = *nr,
-                _ => skipf[idx] = find_fixed_streak_forward(idx, &field),
+                _ => fwd[idx] = find_fixed_streak_forward(idx, &self.field),
             }
         }
 
-        let mut skipb = vec![0; NUM_FIELDS + 1];
+        let bwd = &mut self.skip_backward;
-        for (idx, nr) in field.iter().enumerate().rev() {
+        for (idx, nr) in self.field.iter().enumerate().rev() {
             match nr {
-                0 => skipb[idx + 1] = *nr,
+                0 => bwd[idx + 1] = *nr,
-                _ => skipb[idx + 1] = find_fixed_streak_backward(idx, &field),
+                _ => bwd[idx + 1] = find_fixed_streak_backward(idx, &self.field),
             }
         }
-
-        SField {
-            field,
-            skipf,
-            skipb,
-            pos: 0,
-            possible_values: vec![vec![]; SIZE * SIZE],
-        }
     }
 
     fn build_possible_values_db(&mut self) {
@@ -84,7 +108,7 @@ impl SField {
             self.pos = idx;
             // try all values between 1 and =self.size and remember the good ones
             let mut good_ones = Vec::with_capacity(SIZE);
-            for nr in 1..=(SIZE as u8) {
+            for nr in 1..=(u8::try_from(SIZE).expect("SIZE is too big")) {
                 if self.ok(nr) {
                     good_ones.push(nr);
                 }
@@ -101,9 +125,9 @@ impl SField {
             if !self.put_valid_nr() {
                 self.clear_current_field();
                 if !self.prev() {
-                    self.print_clear();
+                    print_clear();
                     self.print();
-                    println!("Number of solutions: {}", num_solutions);
+                    println!("Number of solutions: {num_solutions}");
                     break;
                 }
                 continue;
@@ -112,9 +136,9 @@ impl SField {
             if !self.next() {
                 num_solutions += 1;
                 if num_solutions % 10_000 == 0 {
-                    self.print_clear();
+                    print_clear();
                     self.print();
-                    println!("Number of solutions: {}", num_solutions);
+                    println!("Number of solutions: {num_solutions}");
                 }
 
                 self.clear_current_field();
@@ -125,22 +149,6 @@ impl SField {
         num_solutions > 0
     }
 
-    fn print_gray(&self) {
-        print!("\x1b\x5b\x31\x3b\x33\x30\x6d");
-    }
-
-    fn print_green(&self) {
-        print!("\x1b\x5b\x31\x3b\x33\x32\x6d");
-    }
-
-    fn print_neutral(&self) {
-        print!("\x1b\x5b\x31\x3b\x30\x6d");
-    }
-
-    fn print_clear(&self) {
-        print!("\x1b\x5b\x48\x1b\x5b\x32\x4a");
-    }
-
     fn print(&self) {
         for i in 0..NUM_FIELDS {
             if i != 0 && i % SIZE == 0 {
@@ -148,15 +156,15 @@ impl SField {
             }
 
             if i == self.pos {
-                self.print_green();
+                print_green();
             } else if self.get_field_at_pos(i) == 0 {
-                self.print_gray();
+                print_gray();
             }
 
             print!("{:2} ", self.get_field_at_pos(i));
 
             if i == self.pos || self.get_field_at_pos(i) == 0 {
-                self.print_neutral();
+                print_neutral();
             }
         }
         println!();
@@ -174,7 +182,7 @@ impl SField {
         //     so self.pos can safely be used to index here
         let possible_vals = &self.possible_values[self.pos];
 
-        for nr in possible_vals.iter() {
+        for nr in possible_vals {
             if *nr <= current_nr {
                 continue;
             }
@@ -246,7 +254,7 @@ impl SField {
     }
 
     fn next(&mut self) -> bool {
-        let new_pos = self.pos + 1 + self.skipf[self.pos + 1] as usize;
+        let new_pos = self.pos + 1 + self.skip_forward[self.pos + 1] as usize;
 
         if new_pos >= NUM_FIELDS {
             return false;
@@ -257,7 +265,7 @@ impl SField {
     }
 
     fn prev(&mut self) -> bool {
-        let new_pos = self.pos - 1 - self.skipb[self.pos] as usize;
+        let new_pos = self.pos - 1 - self.skip_backward[self.pos] as usize;
 
         if new_pos >= NUM_FIELDS {
             return false;
@@ -276,17 +284,7 @@ impl SField {
     }
 }
 
-fn run() -> Result<(), String> {
-    let mut field = SField::new();
-
-    field.build_possible_values_db();
-
-    field.solve();
-    Ok(())
-}
-
 fn main() {
-    if let Err(e) = run() {
+    let mut field = SField::new();
-        println!("{}", e)
+    field.solve();
-    }
 }