my solutions to advent of code
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aoc
advent-of-code
1const std = @import("std");
2
3// Although this function looks imperative, it does not perform the build
4// directly and instead it mutates the build graph (`b`) that will be then
5// executed by an external runner. The functions in `std.Build` implement a DSL
6// for defining build steps and express dependencies between them, allowing the
7// build runner to parallelize the build automatically (and the cache system to
8// know when a step doesn't need to be re-run).
9pub fn build(b: *std.Build) void {
10 // Standard target options allow the person running `zig build` to choose
11 // what target to build for. Here we do not override the defaults, which
12 // means any target is allowed, and the default is native. Other options
13 // for restricting supported target set are available.
14 const target = b.standardTargetOptions(.{});
15 // Standard optimization options allow the person running `zig build` to select
16 // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
17 // set a preferred release mode, allowing the user to decide how to optimize.
18 const optimize = b.standardOptimizeOption(.{});
19 // It's also possible to define more custom flags to toggle optional features
20 // of this build script using `b.option()`. All defined flags (including
21 // target and optimize options) will be listed when running `zig build --help`
22 // in this directory.
23
24 // This creates a module, which represents a collection of source files alongside
25 // some compilation options, such as optimization mode and linked system libraries.
26 // Zig modules are the preferred way of making Zig code available to consumers.
27 // addModule defines a module that we intend to make available for importing
28 // to our consumers. We must give it a name because a Zig package can expose
29 // multiple modules and consumers will need to be able to specify which
30 // module they want to access.
31
32 // Here we define an executable. An executable needs to have a root module
33 // which needs to expose a `main` function. While we could add a main function
34 // to the module defined above, it's sometimes preferable to split business
35 // logic and the CLI into two separate modules.
36 //
37 // If your goal is to create a Zig library for others to use, consider if
38 // it might benefit from also exposing a CLI tool. A parser library for a
39 // data serialization format could also bundle a CLI syntax checker, for example.
40 //
41 // If instead your goal is to create an executable, consider if users might
42 // be interested in also being able to embed the core functionality of your
43 // program in their own executable in order to avoid the overhead involved in
44 // subprocessing your CLI tool.
45 //
46 // If neither case applies to you, feel free to delete the declaration you
47 // don't need and to put everything under a single module.
48 const exe = b.addExecutable(.{
49 .name = "zig",
50 .root_module = b.createModule(.{
51 // b.createModule defines a new module just like b.addModule but,
52 // unlike b.addModule, it does not expose the module to consumers of
53 // this package, which is why in this case we don't have to give it a name.
54 .root_source_file = b.path("src/main.zig"),
55 // Target and optimization levels must be explicitly wired in when
56 // defining an executable or library (in the root module), and you
57 // can also hardcode a specific target for an executable or library
58 // definition if desireable (e.g. firmware for embedded devices).
59 .target = target,
60 .optimize = optimize,
61 // List of modules available for import in source files part of the
62 // root module.
63 }),
64 });
65
66 // This declares intent for the executable to be installed into the
67 // install prefix when running `zig build` (i.e. when executing the default
68 // step). By default the install prefix is `zig-out/` but can be overridden
69 // by passing `--prefix` or `-p`.
70 b.installArtifact(exe);
71
72 // This creates a top level step. Top level steps have a name and can be
73 // invoked by name when running `zig build` (e.g. `zig build run`).
74 // This will evaluate the `run` step rather than the default step.
75 // For a top level step to actually do something, it must depend on other
76 // steps (e.g. a Run step, as we will see in a moment).
77 const run_step = b.step("run", "Run the app");
78
79 // This creates a RunArtifact step in the build graph. A RunArtifact step
80 // invokes an executable compiled by Zig. Steps will only be executed by the
81 // runner if invoked directly by the user (in the case of top level steps)
82 // or if another step depends on it, so it's up to you to define when and
83 // how this Run step will be executed. In our case we want to run it when
84 // the user runs `zig build run`, so we create a dependency link.
85 const run_cmd = b.addRunArtifact(exe);
86 run_step.dependOn(&run_cmd.step);
87
88 // By making the run step depend on the default step, it will be run from the
89 // installation directory rather than directly from within the cache directory.
90 run_cmd.step.dependOn(b.getInstallStep());
91
92 // This allows the user to pass arguments to the application in the build
93 // command itself, like this: `zig build run -- arg1 arg2 etc`
94 if (b.args) |args| {
95 run_cmd.addArgs(args);
96 }
97
98 // Creates an executable that will run `test` blocks from the executable's
99 // root module. Note that test executables only test one module at a time,
100 // hence why we have to create two separate ones.
101 const exe_tests = b.addTest(.{
102 .root_module = exe.root_module,
103 });
104
105 // A run step that will run the second test executable.
106 const run_exe_tests = b.addRunArtifact(exe_tests);
107
108 // A top level step for running all tests. dependOn can be called multiple
109 // times and since the two run steps do not depend on one another, this will
110 // make the two of them run in parallel.
111 const test_step = b.step("test", "Run tests");
112 test_step.dependOn(&run_exe_tests.step);
113
114 // Just like flags, top level steps are also listed in the `--help` menu.
115 //
116 // The Zig build system is entirely implemented in userland, which means
117 // that it cannot hook into private compiler APIs. All compilation work
118 // orchestrated by the build system will result in other Zig compiler
119 // subcommands being invoked with the right flags defined. You can observe
120 // these invocations when one fails (or you pass a flag to increase
121 // verbosity) to validate assumptions and diagnose problems.
122 //
123 // Lastly, the Zig build system is relatively simple and self-contained,
124 // and reading its source code will allow you to master it.
125}