+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("lc3-vm_zig", .{
+ // 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
+ // 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 = "lc3-vm_zig",
+ .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 "lc3-vm_zig" is the name you will use in your source code to
+ // import this module (e.g. `@import("lc3-vm_zig")`). 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 = "lc3-vm_zig", .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.
+}
projects / lc3vm.zig.git / commitdiff