commit ae2c125e2ec8d5dcf31c39891022f9a7880ee5c8 Author: Pascal Le Merrer Date: Sun Mar 1 23:13:02 2026 +0100 Implement the mars rover control diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..3389c86 --- /dev/null +++ b/.gitignore @@ -0,0 +1,2 @@ +.zig-cache/ +zig-out/ diff --git a/build.zig b/build.zig new file mode 100644 index 0000000..3805a6a --- /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("MarsRover", .{ + // 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 = "MarsRover", + .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 "MarsRover" is the name you will use in your source code to + // import this module (e.g. `@import("MarsRover")`). 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 = "MarsRover", .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..f272403 --- /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 = .MarsRover, + // 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 = 0xf4bf0e584db88305, // 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 = "0.15.2", + // 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/devbox.json b/devbox.json new file mode 100644 index 0000000..74a1925 --- /dev/null +++ b/devbox.json @@ -0,0 +1,14 @@ +{ + "$schema": "https://raw.githubusercontent.com/jetify-com/devbox/0.16.0/.schema/devbox.schema.json", + "packages": ["zig@latest"], + "shell": { + "init_hook": [ + "echo 'Welcome to devbox!' > /dev/null" + ], + "scripts": { + "test": [ + "echo \"Error: no test specified\" && exit 1" + ] + } + } +} diff --git a/devbox.lock b/devbox.lock new file mode 100644 index 0000000..3070dca --- /dev/null +++ b/devbox.lock @@ -0,0 +1,73 @@ +{ + "lockfile_version": "1", + "packages": { + "github:NixOS/nixpkgs/nixpkgs-unstable": { + "last_modified": "2026-02-27T06:27:13Z", + "resolved": "github:NixOS/nixpkgs/c0f3d81a7ddbc2b1332be0d8481a672b4f6004d6?lastModified=1772173633&narHash=sha256-MOH58F4AIbCkh6qlQcwMycyk5SWvsqnS%2FTCfnqDlpj4%3D" + }, + "zig@latest": { + "last_modified": "2026-02-23T15:40:43Z", + "resolved": "github:NixOS/nixpkgs/80d901ec0377e19ac3f7bb8c035201e2e098cc97#zig", + "source": "devbox-search", + "version": "0.15.2", + "systems": { + "aarch64-darwin": { + "outputs": [ + { + "name": "out", + "path": "/nix/store/60igbrpnlhn03zk7yj67ih9bnwv0v6b2-zig-0.15.2", + "default": true + }, + { + "name": "doc", + "path": "/nix/store/94hnd63aaklvwy089ajis1ail1m08dvd-zig-0.15.2-doc" + } + ], + "store_path": "/nix/store/60igbrpnlhn03zk7yj67ih9bnwv0v6b2-zig-0.15.2" + }, + "aarch64-linux": { + "outputs": [ + { + "name": "out", + "path": "/nix/store/im165fkysp0db5mn8ic547b9hvw0sklx-zig-0.15.2", + "default": true + }, + { + "name": "doc", + "path": "/nix/store/i3j0ykam2xn564qf1pkni35jdylk05hd-zig-0.15.2-doc" + } + ], + "store_path": "/nix/store/im165fkysp0db5mn8ic547b9hvw0sklx-zig-0.15.2" + }, + "x86_64-darwin": { + "outputs": [ + { + "name": "out", + "path": "/nix/store/n9fa7by83xpk2mhszc8xg5yyacm1qpsm-zig-0.15.2", + "default": true + }, + { + "name": "doc", + "path": "/nix/store/7hslslry24ykp79wpkabi1l2zjp93yg8-zig-0.15.2-doc" + } + ], + "store_path": "/nix/store/n9fa7by83xpk2mhszc8xg5yyacm1qpsm-zig-0.15.2" + }, + "x86_64-linux": { + "outputs": [ + { + "name": "out", + "path": "/nix/store/kfy6nkp1j0h3iyzls3qdqd1ppngzwm4c-zig-0.15.2", + "default": true + }, + { + "name": "doc", + "path": "/nix/store/28bj1cz4q888glmr1n5gnrw86nj473yi-zig-0.15.2-doc" + } + ], + "store_path": "/nix/store/kfy6nkp1j0h3iyzls3qdqd1ppngzwm4c-zig-0.15.2" + } + } + } + } +} diff --git a/src/main.zig b/src/main.zig new file mode 100644 index 0000000..8ee1abf --- /dev/null +++ b/src/main.zig @@ -0,0 +1,233 @@ +const std = @import("std"); + +const Orientation = union(enum) { + North, + South, + East, + West, +}; + +const MarsRover = struct { + x: i8 = 0, + y: i8 = 0, + orientation: Orientation = Orientation.North, + + fn executeCommands(self: *MarsRover, commands: []const u8) void { + std.debug.print("Commands: {s}\n", .{commands}); + for (commands) |command| { + switch (command) { + 'F' => self.moveForward(), + 'B' => self.moveBackward(), + 'R' => self.rotateRight(), + 'L' => self.rotateLeft(), + else => std.debug.print("Unknown command {}\n", .{command}), + } + } + } + + fn moveForward(self: *MarsRover) void { + switch (self.orientation) { + Orientation.North => self.y += 1, + Orientation.East => self.x += 1, + Orientation.South => self.y -= 1, + Orientation.West => self.x -= 1, + } + } + + fn moveBackward(self: *MarsRover) void { + switch (self.orientation) { + Orientation.North => self.y -= 1, + Orientation.East => self.x -= 1, + Orientation.South => self.y += 1, + Orientation.West => self.x += 1, + } + } + + fn rotateRight(self: *MarsRover) void { + switch (self.orientation) { + Orientation.North => self.orientation = Orientation.East, + Orientation.East => self.orientation = Orientation.South, + Orientation.South => self.orientation = Orientation.West, + Orientation.West => self.orientation = Orientation.North, + } + } + + fn rotateLeft(self: *MarsRover) void { + switch (self.orientation) { + Orientation.North => self.orientation = Orientation.West, + Orientation.East => self.orientation = Orientation.North, + Orientation.South => self.orientation = Orientation.East, + Orientation.West => self.orientation = Orientation.South, + } + } +}; + +test "New rover should face North, and be on origin" { + const mars_rover = MarsRover{}; + + try std.testing.expectEqual(0, mars_rover.x); + try std.testing.expectEqual(0, mars_rover.y); + try std.testing.expectEqual(Orientation.North, mars_rover.orientation); +} + +test "When facing north and given command F, rover should move from 1 position towards north" { + var mars_rover = MarsRover{}; + mars_rover.executeCommands("F"); + + try std.testing.expectEqual(0, mars_rover.x); + try std.testing.expectEqual(1, mars_rover.y); + try std.testing.expectEqual(Orientation.North, mars_rover.orientation); +} + +test "When facing east and given command F, rover should move from 1 position towards east" { + var mars_rover = MarsRover{}; + mars_rover.executeCommands("RF"); + + try std.testing.expectEqual(1, mars_rover.x); + try std.testing.expectEqual(0, mars_rover.y); + try std.testing.expectEqual(Orientation.East, mars_rover.orientation); +} + +test "When facing west and given command F, rover should move from 1 position towards west" { + var mars_rover = MarsRover{}; + mars_rover.executeCommands("LF"); + + try std.testing.expectEqual(-1, mars_rover.x); + try std.testing.expectEqual(0, mars_rover.y); + try std.testing.expectEqual(Orientation.West, mars_rover.orientation); +} + +test "When facing south and given command F, rover should move from 1 position towards south" { + var mars_rover = MarsRover{}; + mars_rover.executeCommands("LLF"); + + try std.testing.expectEqual(0, mars_rover.x); + try std.testing.expectEqual(-1, mars_rover.y); + try std.testing.expectEqual(Orientation.South, mars_rover.orientation); +} + +test "When facing north and given commands FF, rover should move from 2 positions towards north" { + var mars_rover = MarsRover{}; + mars_rover.executeCommands("FF"); + + try std.testing.expectEqual(0, mars_rover.x); + try std.testing.expectEqual(2, mars_rover.y); + try std.testing.expectEqual(Orientation.North, mars_rover.orientation); +} + +test "When facing north and given command B, rover should move from 1 position towards south" { + var mars_rover = MarsRover{}; + mars_rover.executeCommands("B"); + + try std.testing.expectEqual(0, mars_rover.x); + try std.testing.expectEqual(-1, mars_rover.y); + try std.testing.expectEqual(Orientation.North, mars_rover.orientation); +} + +test "When facing east and given command B, rover should move from 1 position towards west" { + var mars_rover = MarsRover{}; + mars_rover.executeCommands("RB"); + + try std.testing.expectEqual(-1, mars_rover.x); + try std.testing.expectEqual(0, mars_rover.y); + try std.testing.expectEqual(Orientation.East, mars_rover.orientation); +} + +test "When facing west and given command B, rover should move from 1 position towards east" { + var mars_rover = MarsRover{}; + mars_rover.executeCommands("LB"); + + try std.testing.expectEqual(1, mars_rover.x); + try std.testing.expectEqual(0, mars_rover.y); + try std.testing.expectEqual(Orientation.West, mars_rover.orientation); +} + +test "When facing south and given command B, rover should move from 1 position towards north" { + var mars_rover = MarsRover{}; + mars_rover.executeCommands("LLB"); + + try std.testing.expectEqual(0, mars_rover.x); + try std.testing.expectEqual(1, mars_rover.y); + try std.testing.expectEqual(Orientation.South, mars_rover.orientation); +} + +test "When facing north and given command R, rover should face east" { + var mars_rover = MarsRover{}; + mars_rover.executeCommands("R"); + + try std.testing.expectEqual(0, mars_rover.x); + try std.testing.expectEqual(0, mars_rover.y); + try std.testing.expectEqual(Orientation.East, mars_rover.orientation); +} + +test "When facing north and given commands RR, rover should face south" { + var mars_rover = MarsRover{}; + mars_rover.executeCommands("RR"); + + try std.testing.expectEqual(0, mars_rover.x); + try std.testing.expectEqual(0, mars_rover.y); + try std.testing.expectEqual(Orientation.South, mars_rover.orientation); +} + +test "When facing north and given commands RRR, rover should face west" { + var mars_rover = MarsRover{}; + mars_rover.executeCommands("RRR"); + + try std.testing.expectEqual(0, mars_rover.x); + try std.testing.expectEqual(0, mars_rover.y); + try std.testing.expectEqual(Orientation.West, mars_rover.orientation); +} + +test "When facing north and given commands RRRR, rover should face north again" { + var mars_rover = MarsRover{}; + mars_rover.executeCommands("RRRR"); + + try std.testing.expectEqual(0, mars_rover.x); + try std.testing.expectEqual(0, mars_rover.y); + try std.testing.expectEqual(Orientation.North, mars_rover.orientation); +} + +test "When facing north and given command L, rover should face west" { + var mars_rover = MarsRover{}; + mars_rover.executeCommands("L"); + + try std.testing.expectEqual(0, mars_rover.x); + try std.testing.expectEqual(0, mars_rover.y); + try std.testing.expectEqual(Orientation.West, mars_rover.orientation); +} + +test "When facing north and given commands LL, rover should face south" { + var mars_rover = MarsRover{}; + mars_rover.executeCommands("LL"); + + try std.testing.expectEqual(0, mars_rover.x); + try std.testing.expectEqual(0, mars_rover.y); + try std.testing.expectEqual(Orientation.South, mars_rover.orientation); +} + +test "When facing north and given commands LLL, rover should face east" { + var mars_rover = MarsRover{}; + mars_rover.executeCommands("LLL"); + + try std.testing.expectEqual(0, mars_rover.x); + try std.testing.expectEqual(0, mars_rover.y); + try std.testing.expectEqual(Orientation.East, mars_rover.orientation); +} + +test "When facing north and given commands LLLL, rover should face north again" { + var mars_rover = MarsRover{}; + mars_rover.executeCommands("LLLL"); + + try std.testing.expectEqual(0, mars_rover.x); + try std.testing.expectEqual(0, mars_rover.y); + try std.testing.expectEqual(Orientation.North, mars_rover.orientation); +} + +test "a series of various commands should move the rover to the expected position" { + var mars_rover = MarsRover{}; + mars_rover.executeCommands("RFFLFFRFFB"); + + try std.testing.expectEqual(3, mars_rover.x); + try std.testing.expectEqual(2, mars_rover.y); + try std.testing.expectEqual(Orientation.East, mars_rover.orientation); +} diff --git a/src/marsrover.zig b/src/marsrover.zig new file mode 100644 index 0000000..94c7cd0 --- /dev/null +++ b/src/marsrover.zig @@ -0,0 +1,23 @@ +//! By convention, root.zig is the root source file when making a library. +const std = @import("std"); + +pub fn bufferedPrint() !void { + // Stdout is for the actual output of your application, for example if you + // are implementing gzip, then only the compressed bytes should be sent to + // stdout, not any debugging messages. + var stdout_buffer: [1024]u8 = undefined; + var stdout_writer = std.fs.File.stdout().writer(&stdout_buffer); + const stdout = &stdout_writer.interface; + + try stdout.print("Run `zig build test` to run the tests.\n", .{}); + + try stdout.flush(); // Don't forget to flush! +} + +pub fn add(a: i32, b: i32) i32 { + return a + b; +} + +test "basic add functionality" { + try std.testing.expect(add(3, 7) == 10); +}