From e71decc677995e321e18781755778e8ef6937fc6 Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Fri, 16 Dec 2022 11:28:33 -0500
Subject: [PATCH] Separate out some code into a shared library

---
 aoc-shared/Cargo.lock  |   7 +++
 aoc-shared/Cargo.toml  |   8 +++
 aoc-shared/src/grid.rs | 108 +++++++++++++++++++++++++++++++++++++++++
 aoc-shared/src/lib.rs  |   2 +
 4 files changed, 125 insertions(+)
 create mode 100644 aoc-shared/Cargo.lock
 create mode 100644 aoc-shared/Cargo.toml
 create mode 100644 aoc-shared/src/grid.rs
 create mode 100644 aoc-shared/src/lib.rs

diff --git a/aoc-shared/Cargo.lock b/aoc-shared/Cargo.lock
new file mode 100644
index 0000000..f517cd2
--- /dev/null
+++ b/aoc-shared/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "aoc-shared"
+version = "0.1.0"
diff --git a/aoc-shared/Cargo.toml b/aoc-shared/Cargo.toml
new file mode 100644
index 0000000..ca58dcd
--- /dev/null
+++ b/aoc-shared/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "aoc-shared"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/aoc-shared/src/grid.rs b/aoc-shared/src/grid.rs
new file mode 100644
index 0000000..7d2027e
--- /dev/null
+++ b/aoc-shared/src/grid.rs
@@ -0,0 +1,108 @@
+/// Reusing part of day 8's solution for a virtual 2d grid
+
+#[derive(Debug)]
+pub struct Grid<T> {
+    width: usize,
+    pub vec: Vec<T>,
+}
+
+pub trait Grid2d<T> {
+    fn new(width: usize) -> Self;
+
+    fn len(&self) -> usize;
+
+    fn num_cols(&self) -> usize;
+
+    fn num_rows(&self) -> usize {
+        self.len() / self.num_cols()
+    }
+
+    // Convert x,y coordinate into linear array index
+    fn xy_idx(&self, x: usize, y: usize) -> usize {
+        (y * self.num_cols()) + x
+    }
+
+    /// Convert linear array index to x,y coordinate
+    fn idx_xy(&self, idx: usize) -> (usize, usize) {
+        (idx % self.num_cols(), idx / self.num_cols())
+    }
+
+    fn get(&self, idx: usize) -> Option<&T>;
+
+    fn get_mut(&mut self, idx: usize) -> Option<&mut T>;
+
+    fn get_row(&mut self, row_num: usize) -> &mut [T];
+
+    fn row_first_idx(&self, row: usize) -> usize {
+        let idx = row * self.num_cols();
+
+        if idx < self.len() {
+            idx
+        } else {
+            self.len()
+        }
+    }
+
+    fn row_last_idx(&self, row: usize) -> usize {
+        if (row + 1) > self.num_rows() {
+            return self.len();
+        }
+
+        self.row_first_idx(row + 1) - 1
+    }
+
+    fn get_row_indexes(&self, row_num: usize) -> Vec<usize> {
+        (self.row_first_idx(row_num)..=self.row_last_idx(row_num)).collect()
+    }
+
+    fn get_column_indexes(&self, col_num: usize) -> Vec<usize> {
+        let mut indexes = Vec::new();
+
+        if col_num >= self.num_cols() {
+            panic!(
+                "Asked for column {}, there are {} columns",
+                col_num,
+                self.num_cols()
+            );
+        }
+
+        for r in 0..self.num_rows() {
+            let idx = self.num_cols() * r + col_num;
+            indexes.push(idx);
+        }
+
+        indexes
+    }
+}
+
+impl<T> Grid2d<T> for Grid<T> {
+    fn new(width: usize) -> Self {
+        Grid {
+            width,
+            vec: Vec::new(),
+        }
+    }
+
+    fn len(&self) -> usize {
+        self.vec.len()
+    }
+
+    fn num_cols(&self) -> usize {
+        self.width
+    }
+
+    fn get(&self, idx: usize) -> Option<&T> {
+        self.vec.get(idx)
+    }
+
+    fn get_mut(&mut self, idx: usize) -> Option<&mut T> {
+        self.vec.get_mut(idx)
+    }
+
+    fn get_row(&mut self, row_num: usize) -> &mut [T] {
+        let start = self.row_first_idx(row_num);
+        let end = self.row_last_idx(row_num);
+
+        &mut self.vec[start..=end]
+    }
+}
diff --git a/aoc-shared/src/lib.rs b/aoc-shared/src/lib.rs
new file mode 100644
index 0000000..204404f
--- /dev/null
+++ b/aoc-shared/src/lib.rs
@@ -0,0 +1,2 @@
+pub mod grid;
+pub use grid::*;