commit ad8b15806771767a790f72c4767b4b3c73f09487 Author: Reduan204 Date: Fri Aug 21 03:47:26 2026 +0100 first commit diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..1dfcbd2 --- /dev/null +++ b/.gitignore @@ -0,0 +1 @@ +.zig-cache/ diff --git a/build.zig b/build.zig new file mode 100644 index 0000000..b91fb7f --- /dev/null +++ b/build.zig @@ -0,0 +1,156 @@ +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 = &.{ + // 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. +} diff --git a/build.zig.zon b/build.zig.zon new file mode 100644 index 0000000..cf4a495 --- /dev/null +++ b/build.zig.zon @@ -0,0 +1,81 @@ +.{ + // This is the default name used by packages depending on this one. For + // example, when a user runs `zig fetch --save `, this field is used + // as the key in the `dependencies` table. Although the user can choose a + // different name, most users will stick with this provided value. + // + // It is redundant to include "zig" in this name because it is already + // within the Zig package namespace. + .name = ._2048zig, + // This is a [Semantic Version](https://semver.org/). + // In a future version of Zig it will be used for package deduplication. + .version = "0.0.0", + // Together with name, this represents a globally unique package + // identifier. This field is generated by the Zig toolchain when the + // package is first created, and then *never changes*. This allows + // unambiguous detection of one package being an updated version of + // another. + // + // When forking a Zig project, this id should be regenerated (delete the + // field and run `zig build`) if the upstream project is still maintained. + // Otherwise, the fork is *hostile*, attempting to take control over the + // original project's identity. Thus it is recommended to leave the comment + // on the following line intact, so that it shows up in code reviews that + // modify the field. + .fingerprint = 0x8d138a4e0b2ef51e, // Changing this has security and trust implications. + // Tracks the earliest Zig version that the package considers to be a + // supported use case. + .minimum_zig_version = "0.16.0", + // This field is optional. + // Each dependency must either provide a `url` and `hash`, or a `path`. + // `zig build --fetch` can be used to fetch all dependencies of a package, recursively. + // Once all dependencies are fetched, `zig build` no longer requires + // internet connectivity. + .dependencies = .{ + // See `zig fetch --save ` for a command-line interface for adding dependencies. + //.example = .{ + // // When updating this field to a new URL, be sure to delete the corresponding + // // `hash`, otherwise you are communicating that you expect to find the old hash at + // // the new URL. If the contents of a URL change this will result in a hash mismatch + // // which will prevent zig from using it. + // .url = "https://example.com/foo.tar.gz", + // + // // This is computed from the file contents of the directory of files that is + // // obtained after fetching `url` and applying the inclusion rules given by + // // `paths`. + // // + // // This field is the source of truth; packages do not come from a `url`; they + // // come from a `hash`. `url` is just one of many possible mirrors for how to + // // obtain a package matching this `hash`. + // // + // // Uses the [multihash](https://multiformats.io/multihash/) format. + // .hash = "...", + // + // // When this is provided, the package is found in a directory relative to the + // // build root. In this case the package's hash is irrelevant and therefore not + // // computed. This field and `url` are mutually exclusive. + // .path = "foo", + // + // // When this is set to `true`, a package is declared to be lazily + // // fetched. This makes the dependency only get fetched if it is + // // actually used. + // .lazy = false, + //}, + }, + // Specifies the set of files and directories that are included in this package. + // Only files and directories listed here are included in the `hash` that + // is computed for this package. Only files listed here will remain on disk + // when using the zig package manager. As a rule of thumb, one should list + // files required for compilation plus any license(s). + // Paths are relative to the build root. Use the empty string (`""`) to refer to + // the build root itself. + // A directory listed here means that all files within, recursively, are included. + .paths = .{ + "build.zig", + "build.zig.zon", + "src", + // For example... + //"LICENSE", + //"README.md", + }, +} diff --git a/src/game.zig b/src/game.zig new file mode 100644 index 0000000..64ec762 --- /dev/null +++ b/src/game.zig @@ -0,0 +1,123 @@ +//! 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; + } +}; diff --git a/src/main.zig b/src/main.zig new file mode 100644 index 0000000..2f243a4 --- /dev/null +++ b/src/main.zig @@ -0,0 +1,34 @@ +//! main.zig — program entry point: sets up a board and shows it. +const game = @import("game.zig"); +const std = @import("std"); + +pub fn main() !void { + // `var` (not const) because the board changes during play. + var board: game.Board = .{}; + + // Random number generator. The seed (42) makes every run + // identical for now — handy for debugging, we'll fix it later. + var prng = std.Random.DefaultPrng.init(42); + const rand = prng.random(); + + 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("\n", .{}); + } +} diff --git a/src/root.zig b/src/root.zig new file mode 100644 index 0000000..5a71250 --- /dev/null +++ b/src/root.zig @@ -0,0 +1,18 @@ +//! 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); +} diff --git a/zig-out/bin/_2048zig b/zig-out/bin/_2048zig new file mode 100755 index 0000000..3c8109b Binary files /dev/null and b/zig-out/bin/_2048zig differ