diff options
Diffstat (limited to 'build.zig')
| -rw-r--r-- | build.zig | 186 |
1 files changed, 128 insertions, 58 deletions
@@ -1,72 +1,121 @@ const std = @import("std"); -// Although this function looks imperative, note that its job is to -// declaratively construct a build graph that will be executed by an external -// runner. +// 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 allows the person running `zig build` to choose + // 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(.{}); - - const lib_mod = b.createModule(.{ + // 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("zaprus", .{ + // 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, - .optimize = optimize, - }); - - // We will also create a module for our other entry point, 'main.zig'. - const exe_mod = b.createModule(.{ - // `root_source_file` is the Zig "entry point" of the module. If a module - // only contains e.g. external object files, you can make this `null`. - // In this case the main source file is merely a path, however, in more - // complicated build scripts, this could be a generated file. - .root_source_file = b.path("src/main.zig"), - .target = target, - .optimize = optimize, - }); - - lib_mod.addImport("network", b.dependency("network", .{}).module("network")); - lib_mod.addImport("gatorcat", b.dependency("gatorcat", .{}).module("gatorcat")); - - exe_mod.addImport("zaprus", lib_mod); - exe_mod.addImport("clap", b.dependency("clap", .{}).module("clap")); - - const lib = b.addLibrary(.{ - .linkage = .static, - .name = "zaprus", - .root_module = lib_mod, }); - b.installArtifact(lib); - - // This creates another `std.Build.Step.Compile`, but this one builds an executable - // rather than a static library. + mod.addImport("network", b.dependency("network", .{}).module("network")); + mod.addImport("gatorcat", b.dependency("gatorcat", .{}).module("gatorcat")); + + // 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 + // 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 = "zaprus", - .root_module = exe_mod, + .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 "zaprus" is the name you will use in your source code to + // import this module (e.g. `@import("zaprus")`). 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 = "zaprus", .module = mod }, + .{ .name = "clap", .module = b.dependency("clap", .{}).module("clap") }, + }, + }), }); // This declares intent for the executable to be installed into the - // standard location when the user invokes the "install" step (the default - // step when running `zig build`). + // 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); + b.installArtifact(b.addLibrary(.{ + .linkage = .static, + .name = "zaprus", + .root_module = mod, + })); + + // 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 Run step in the build graph, to be executed when another - // step is evaluated that depends on it. The next line below will establish - // such a dependency. + // 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 install step, it will be run from the + // 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. - // This is not necessary, however, if the application depends on other installed - // files, this ensures they will be present and in the expected location. run_cmd.step.dependOn(b.getInstallStep()); // This allows the user to pass arguments to the application in the build @@ -75,21 +124,42 @@ pub fn build(b: *std.Build) void { run_cmd.addArgs(args); } - // This creates a build step. It will be visible in the `zig build --help` menu, - // and can be selected like this: `zig build run` - // This will evaluate the `run` step rather than the default, which is "install". - const run_step = b.step("run", "Run the app"); - run_step.dependOn(&run_cmd.step); - - const exe_unit_tests = b.addTest(.{ - .root_module = exe_mod, + // 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, }); - const run_exe_unit_tests = b.addRunArtifact(exe_unit_tests); + // 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, + }); - // Similar to creating the run step earlier, this exposes a `test` step to - // the `zig build --help` menu, providing a way for the user to request - // running the unit tests. - const test_step = b.step("test", "Run unit tests"); - test_step.dependOn(&run_exe_unit_tests.step); + // 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. } |