Cleanup some stuff

build.zig

@@ -1,156 +1,41 @@
 const std = @import("std");
 
-// Although this function looks imperative, it does not perform the build
-// directly and instead it mutates the build graph (`b`) that will be then
-// executed by an external runner. The functions in `std.Build` implement a DSL
-// for defining build steps and express dependencies between them, allowing the
-// build runner to parallelize the build automatically (and the cache system to
-// know when a step doesn't need to be re-run).
 pub fn build(b: *std.Build) void {
-    // Standard target options allow the person running `zig build` to choose
-    // what target to build for. Here we do not override the defaults, which
-    // means any target is allowed, and the default is native. Other options
-    // for restricting supported target set are available.
     const target = b.standardTargetOptions(.{});
-    // Standard optimization options allow the person running `zig build` to select
+
-    // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
-    // set a preferred release mode, allowing the user to decide how to optimize.
     const optimize = b.standardOptimizeOption(.{});
-    // It's also possible to define more custom flags to toggle optional features
-    // of this build script using `b.option()`. All defined flags (including
-    // target and optimize options) will be listed when running `zig build --help`
-    // in this directory.
 
-    // This creates a module, which represents a collection of source files alongside
-    // some compilation options, such as optimization mode and linked system libraries.
-    // Zig modules are the preferred way of making Zig code available to consumers.
-    // addModule defines a module that we intend to make available for importing
-    // to our consumers. We must give it a name because a Zig package can expose
-    // multiple modules and consumers will need to be able to specify which
-    // module they want to access.
-    const mod = b.addModule("_2048zig", .{
-        // The root source file is the "entry point" of this module. Users of
-        // this module will only be able to access public declarations contained
-        // in this file, which means that if you have declarations that you
-        // intend to expose to consumers that were defined in other files part
-        // of this module, you will have to make sure to re-export them from
-        // the root file.
-        .root_source_file = b.path("src/root.zig"),
-        // Later on we'll use this module as the root module of a test executable
-        // which requires us to specify a target.
-        .target = target,
-    });
-
-    // Here we define an executable. An executable needs to have a root module
-    // which needs to expose a `main` function. While we could add a main function
-    // to the module defined above, it's sometimes preferable to split business
-    // logic and the CLI into two separate modules.
-    //
-    // If your goal is to create a Zig library for others to use, consider if
-    // it might benefit from also exposing a CLI tool. A parser library for a
-    // data serialization format could also bundle a CLI syntax checker, for example.
-    //
-    // If instead your goal is to create an executable, consider if users might
-    // be interested in also being able to embed the core functionality of your
-    // program in their own executable in order to avoid the overhead involved in
-    // subprocessing your CLI tool.
-    //
-    // If neither case applies to you, feel free to delete the declaration you
-    // don't need and to put everything under a single module.
     const exe = b.addExecutable(.{
         .name = "_2048zig",
         .root_module = b.createModule(.{
-            // b.createModule defines a new module just like b.addModule but,
-            // unlike b.addModule, it does not expose the module to consumers of
-            // this package, which is why in this case we don't have to give it a name.
             .root_source_file = b.path("src/main.zig"),
-            // Target and optimization levels must be explicitly wired in when
+
-            // defining an executable or library (in the root module), and you
-            // can also hardcode a specific target for an executable or library
-            // definition if desireable (e.g. firmware for embedded devices).
             .target = target,
             .optimize = optimize,
-            // List of modules available for import in source files part of the
+
-            // root module.
+            .imports = &.{},
-            .imports = &.{
-                // Here "_2048zig" is the name you will use in your source code to
-                // import this module (e.g. `@import("_2048zig")`). The name is
-                // repeated because you are allowed to rename your imports, which
-                // can be extremely useful in case of collisions (which can happen
-                // importing modules from different packages).
-                .{ .name = "_2048zig", .module = mod },
-            },
         }),
     });
 
-    // This declares intent for the executable to be installed into the
-    // install prefix when running `zig build` (i.e. when executing the default
-    // step). By default the install prefix is `zig-out/` but can be overridden
-    // by passing `--prefix` or `-p`.
     b.installArtifact(exe);
 
-    // This creates a top level step. Top level steps have a name and can be
-    // invoked by name when running `zig build` (e.g. `zig build run`).
-    // This will evaluate the `run` step rather than the default step.
-    // For a top level step to actually do something, it must depend on other
-    // steps (e.g. a Run step, as we will see in a moment).
     const run_step = b.step("run", "Run the app");
 
-    // This creates a RunArtifact step in the build graph. A RunArtifact step
-    // invokes an executable compiled by Zig. Steps will only be executed by the
-    // runner if invoked directly by the user (in the case of top level steps)
-    // or if another step depends on it, so it's up to you to define when and
-    // how this Run step will be executed. In our case we want to run it when
-    // the user runs `zig build run`, so we create a dependency link.
     const run_cmd = b.addRunArtifact(exe);
     run_step.dependOn(&run_cmd.step);
 
-    // By making the run step depend on the default step, it will be run from the
-    // installation directory rather than directly from within the cache directory.
     run_cmd.step.dependOn(b.getInstallStep());
 
-    // This allows the user to pass arguments to the application in the build
-    // command itself, like this: `zig build run -- arg1 arg2 etc`
     if (b.args) |args| {
         run_cmd.addArgs(args);
     }
 
-    // Creates an executable that will run `test` blocks from the provided module.
-    // Here `mod` needs to define a target, which is why earlier we made sure to
-    // set the releative field.
-    const mod_tests = b.addTest(.{
-        .root_module = mod,
-    });
-
-    // A run step that will run the test executable.
-    const run_mod_tests = b.addRunArtifact(mod_tests);
-
-    // Creates an executable that will run `test` blocks from the executable's
-    // root module. Note that test executables only test one module at a time,
-    // hence why we have to create two separate ones.
     const exe_tests = b.addTest(.{
         .root_module = exe.root_module,
     });
 
-    // A run step that will run the second test executable.
     const run_exe_tests = b.addRunArtifact(exe_tests);
 
-    // A top level step for running all tests. dependOn can be called multiple
-    // times and since the two run steps do not depend on one another, this will
-    // make the two of them run in parallel.
     const test_step = b.step("test", "Run tests");
-    test_step.dependOn(&run_mod_tests.step);
     test_step.dependOn(&run_exe_tests.step);
-
-    // Just like flags, top level steps are also listed in the `--help` menu.
-    //
-    // The Zig build system is entirely implemented in userland, which means
-    // that it cannot hook into private compiler APIs. All compilation work
-    // orchestrated by the build system will result in other Zig compiler
-    // subcommands being invoked with the right flags defined. You can observe
-    // these invocations when one fails (or you pass a flag to increase
-    // verbosity) to validate assumptions and diagnose problems.
-    //
-    // Lastly, the Zig build system is relatively simple and self-contained,
-    // and reading its source code will allow you to master it.
 }

src/board.zig

@@ -0,0 +1,135 @@
+const std = @import("std");
+const Self = @This();
+
+//
+// FIELDS
+//
+
+cells: [4][4]u16 = .{.{0} ** 4} ** 4,
+
+/// ----------------------------------------------------
+/// ----------------------------------------------------
+fn slideRowLeft(row: *[4]u16) void {
+    var write: usize = 0; // where the next tile should land
+
+    // Pass 1: copy every non-zero tile to the next free slot.
+    // `cell` = WHAT we're carrying, `write` = WHERE it lands.
+    for (row) |cell| {
+        if (cell != 0) {
+            row[write] = cell;
+            write += 1;
+        }
+    }
+
+    // Pass 2: everything after the last packed tile becomes 0.
+    for (write..4) |i| {
+        row[i] = 0;
+    }
+}
+
+/// ----------------------------------------------------
+/// Reverses one row in place: [2,0,4,0] becomes [0,4,0,2].
+/// Only visits the first half (i < 2) — otherwise every swap
+/// would be undone by a later swap.
+/// ----------------------------------------------------
+fn reverse(row: *[4]u16) void {
+    for (0..2) |i| {
+        const tmp = row[i]; // remember one cup's contents
+        row[i] = row[3 - i]; // pour the opposite cup into this one
+        row[3 - i] = tmp; // pour the remembered contents back
+    }
+}
+
+/// ----------------------------------------------------
+/// Slides every row to the LEFT, closing up gaps.
+/// ----------------------------------------------------
+pub fn slideLeft(self: *Self) void {
+    // &self.cells = iterate the REAL grid (not a copy),
+    // |*row| = each row by pointer, so edits stick.
+    for (&self.cells) |*row| {
+        slideRowLeft(row); // "hey, slide THIS row"
+    }
+}
+
+/// ----------------------------------------------------
+/// Slides RIGHT = mirror trick: flip each row, slide left,
+/// flip back. What was "toward index 0" becomes "toward index 3".
+/// ----------------------------------------------------
+pub fn slideRight(self: *Self) void {
+    for (&self.cells) |*row| {
+        reverse(row);
+        slideRowLeft(row);
+        reverse(row);
+    }
+}
+
+/// ----------------------------------------------------
+/// Slides UP: pull each COLUMN out into a temp row, slide it,
+/// push it back. In the temp array "left" means "toward row 0",
+/// which is exactly UP on the board.
+/// ----------------------------------------------------
+pub fn slideUp(self: *Self) void {
+    for (0..4) |c| { // c = column number
+        var tmp: [4]u16 = undefined;
+
+        for (0..4) |r| tmp[r] = self.cells[r][c]; // pull column out (top→bottom)
+        slideRowLeft(&tmp); // slide toward top
+        for (0..4) |r| self.cells[r][c] = tmp[r]; // push back in
+    }
+}
+
+/// ----------------------------------------------------
+/// Slides DOWN: same as slideUp, but read/write the column
+/// BOTTOM→top using `3 - r`. The flip makes "toward index 0"
+/// in the temp array mean DOWN on the board.
+/// ----------------------------------------------------
+pub fn slideDown(self: *Self) void {
+    for (0..4) |c| { // c = column number
+        var tmp: [4]u16 = undefined;
+
+        for (0..4) |r| tmp[r] = self.cells[3 - r][c]; // pull column out (bottom→top)
+        slideRowLeft(&tmp); // slide toward index 0...
+        for (0..4) |r| self.cells[3 - r][c] = tmp[r]; // ...which is the bottom, thanks to the flip
+    }
+}
+
+/// ----------------------------------------------------
+/// Spawns a new tile (2 or 4) in a random empty cell.
+/// ----------------------------------------------------
+pub fn spawn(self: *Self, rand: std.Random) void {
+    // --- Phase 1: find every empty cell -------------------
+    // Roll 0..9 once now; we'll use it at the end to decide
+    // 2 vs 4 (a 1-in-10 chance of a 4, like the real game).
+    const n = rand.intRangeAtMost(usize, 0, 9);
+
+    // Fixed-size shelf for cell indexes. The board has at most
+    // 16 empties, so no dynamic memory is ever needed.
+    var empties: [16]usize = undefined;
+    var count: usize = 0; // how many slots of `empties` we filled
+
+    // Walk all 16 cells. Flat index i maps to the grid as:
+    //   row = i / 4,  col = i % 4
+    for (0..16) |i| {
+        if (self.cells[i / 4][i % 4] == 0) {
+            empties[count] = i; // remember WHERE an empty is
+            count += 1;
+        }
+    }
+
+    // Self full → nothing to spawn into, just leave.
+    if (count == 0) {
+        return;
+    }
+
+    // --- Phase 2: pick one empty and fill it --------------
+    const pick = rand.uintLessThan(usize, count); // random 0..count-1
+    const spot = empties[pick]; // flat index of the chosen cell
+
+    const row = spot / 4; // undo the flat-index trick
+    const col = spot % 4;
+
+    var value: u16 = 2; // usually spawn a 2...
+    if (n == 9) value = 4; // ...but our early roll said 9 → lucky 4
+
+    self.cells[row][col] = value;
+}

src/game.zig

@@ -1,123 +0,0 @@
-//! game.zig — the 2048 board and everything it can do.
-const std = @import("std");
-
-/// The 4x4 playing grid. A cell holds the tile VALUE directly:
-/// 0 means "empty", anything else is the number shown on screen.
-pub const Board = struct {
-    cells: [4][4]u16 = .{.{0} ** 4} ** 4,
-
-    /// THE core algorithm: slides ONE row left, closing gaps.
-    /// (Merging equal tiles will be added here later.)
-    /// Used by every direction — right/up/down are just disguises.
-    fn slideRowLeft(row: *[4]u16) void {
-        var write: usize = 0; // where the next tile should land
-
-        // Pass 1: copy every non-zero tile to the next free slot.
-        // `cell` = WHAT we're carrying, `write` = WHERE it lands.
-        for (row) |cell| {
-            if (cell != 0) {
-                row[write] = cell;
-                write += 1;
-            }
-        }
-
-        // Pass 2: everything after the last packed tile becomes 0.
-        for (write..4) |i| {
-            row[i] = 0;
-        }
-    }
-
-    /// Reverses one row in place: [2,0,4,0] becomes [0,4,0,2].
-    /// Only visits the first half (i < 2) — otherwise every swap
-    /// would be undone by a later swap.
-    fn reverse(row: *[4]u16) void {
-        for (0..2) |i| {
-            const tmp = row[i]; // remember one cup's contents
-            row[i] = row[3 - i]; // pour the opposite cup into this one
-            row[3 - i] = tmp; // pour the remembered contents back
-        }
-    }
-
-    /// Slides every row to the LEFT, closing up gaps.
-    pub fn slideLeft(self: *Board) void {
-        // &self.cells = iterate the REAL grid (not a copy),
-        // |*row| = each row by pointer, so edits stick.
-        for (&self.cells) |*row| {
-            slideRowLeft(row); // "hey, slide THIS row"
-        }
-    }
-
-    /// Slides RIGHT = mirror trick: flip each row, slide left,
-    /// flip back. What was "toward index 0" becomes "toward index 3".
-    pub fn slideRight(self: *Board) void {
-        for (&self.cells) |*row| {
-            reverse(row);
-            slideRowLeft(row);
-            reverse(row);
-        }
-    }
-
-    /// Slides UP: pull each COLUMN out into a temp row, slide it,
-    /// push it back. In the temp array "left" means "toward row 0",
-    /// which is exactly UP on the board.
-    pub fn slideUp(self: *Board) void {
-        for (0..4) |c| { // c = column number
-            var tmp: [4]u16 = undefined;
-
-            for (0..4) |r| tmp[r] = self.cells[r][c]; // pull column out (top→bottom)
-            slideRowLeft(&tmp); // slide toward top
-            for (0..4) |r| self.cells[r][c] = tmp[r]; // push back in
-        }
-    }
-
-    /// Slides DOWN: same as slideUp, but read/write the column
-    /// BOTTOM→top using `3 - r`. The flip makes "toward index 0"
-    /// in the temp array mean DOWN on the board.
-    pub fn slideDown(self: *Board) void {
-        for (0..4) |c| { // c = column number
-            var tmp: [4]u16 = undefined;
-
-            for (0..4) |r| tmp[r] = self.cells[3 - r][c]; // pull column out (bottom→top)
-            slideRowLeft(&tmp); // slide toward index 0...
-            for (0..4) |r| self.cells[3 - r][c] = tmp[r]; // ...which is the bottom, thanks to the flip
-        }
-    }
-    /// Spawns a new tile (2 or 4) in a random empty cell.
-    pub fn spawn(self: *Board, rand: std.Random) void {
-        // --- Phase 1: find every empty cell -------------------
-        // Roll 0..9 once now; we'll use it at the end to decide
-        // 2 vs 4 (a 1-in-10 chance of a 4, like the real game).
-        const n = rand.intRangeAtMost(usize, 0, 9);
-
-        // Fixed-size shelf for cell indexes. The board has at most
-        // 16 empties, so no dynamic memory is ever needed.
-        var empties: [16]usize = undefined;
-        var count: usize = 0; // how many slots of `empties` we filled
-
-        // Walk all 16 cells. Flat index i maps to the grid as:
-        //   row = i / 4,  col = i % 4
-        for (0..16) |i| {
-            if (self.cells[i / 4][i % 4] == 0) {
-                empties[count] = i; // remember WHERE an empty is
-                count += 1;
-            }
-        }
-
-        // Board full → nothing to spawn into, just leave.
-        if (count == 0) {
-            return;
-        }
-
-        // --- Phase 2: pick one empty and fill it --------------
-        const pick = rand.uintLessThan(usize, count); // random 0..count-1
-        const spot = empties[pick]; // flat index of the chosen cell
-
-        const row = spot / 4; // undo the flat-index trick
-        const col = spot % 4;
-
-        var value: u16 = 2; // usually spawn a 2...
-        if (n == 9) value = 4; // ...but our early roll said 9 → lucky 4
-
-        self.cells[row][col] = value;
-    }
-};

src/main.zig

@@ -1,10 +1,9 @@
 //! main.zig — program entry point: sets up a board and shows it.
-const game = @import("game.zig");
+const Board = @import("board.zig");
 const std = @import("std");
 
 pub fn main() !void {
-    // `var` (not const) because the board changes during play.
+    var board: Board = .{};
-    var board: game.Board = .{};
 
     // Random number generator. The seed (42) makes every run
     // identical for now — handy for debugging, we'll fix it later.
@@ -13,21 +12,15 @@ pub fn main() !void {
 
     board.spawn(rand); // drop one starting tile onto the board
 
-    // --- TEMPORARY test setup ---------------------------------
-    // Hand-made rows to check the slide functions while we build.
-    // Once the real game loop exists, this block gets deleted and
-    // the board starts empty (two spawned tiles, like real 2048).
     board.cells[0] = .{ 2, 0, 2, 0 };
     board.cells[1] = .{ 0, 4, 4, 0 };
     board.cells[2] = .{ 2, 2, 2, 2 };
     board.cells[3] = .{ 0, 2, 0, 4 };
     board.slideUp(); // ← swap in any direction to test it
 
-    // Print the grid row by row. `{d:4}` = decimal, 4 chars wide,
-    // so the columns line up.
     for (board.cells) |row| {
         for (row) |cell| {
-            std.debug.print("{d:4}", .{cell});
+            std.debug.print("\x1b[31m{d:4}", .{cell});
         }
         std.debug.print("\n", .{});
     }

src/root.zig

@@ -1,18 +0,0 @@
-//! By convention, root.zig is the root source file when making a package.
-const std = @import("std");
-const Io = std.Io;
-
-/// This is a documentation comment to explain the `printAnotherMessage` function below.
-///
-/// Accepting an `Io.Writer` instance is a handy way to write reusable code.
-pub fn printAnotherMessage(writer: *Io.Writer) Io.Writer.Error!void {
-    try writer.print("Run `zig build test` to run the tests.\n", .{});
-}
-
-pub fn add(a: i32, b: i32) i32 {
-    return a + b;
-}
-
-test "basic add functionality" {
-    try std.testing.expect(add(3, 7) == 10);
-}