create build.zig for flex v2.6.4

.github/workflows/ci.yaml

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+name: Continuous Integration
+
+on:
+  push:
+    branches: [main]
+
+  pull_request:
+    branches: [main]
+
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+
+      - name: Set up Zig
+        uses: mlugg/setup-zig@v1
+
+      - name: Run `build`
+        run: zig build

.gitignore

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+.zig-cache/
+zig-out/

LICENSE.md

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+Copyright © 2024 LeRoyce Pearson
+
+Redistribution and use in source and binary forms, with or without 
+modification, are permitted provided that the following conditions are met:
+
+    1. Redistributions of source code must retain the above copyright notice, 
+       this list of conditions and the following disclaimer.
+
+    2. Redistributions in binary form must reproduce the above copyright 
+       notice, this list of conditions and the following disclaimer in the 
+       documentation and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND 
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE 
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

README.md

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+# FLex
+
+[![CI][ci-shd]][ci-url]
+[![License][lc-shd]][lc-url]
+
+## Zig build [FLex](https://github.com/westes/flex)
+
+Uses the release tarball from https://github.com/westes/flex/releases/tag/v2.6.4
+
+Does not currently try to build flex from source, [as building flex requires flex][issue-458].
+
+If you want to build flex from source, the following resources may be helpful:
+
+- https://bootstrapping.miraheze.org/wiki/Live-bootstrap#flex_2.5.11
+- https://github.com/fosslinux/live-bootstrap/tree/master/steps/flex-2.5.11
+- https://en.wikipedia.org/wiki/Flex_(lexical_analyser_generator)
+- https://tomassetti.me/why-you-should-not-use-flex-yacc-and-bison/
+- https://pubs.opengroup.org/onlinepubs/9799919799/utilities/lex.html
+- https://pubs.opengroup.org/onlinepubs/9799919799/utilities/yacc.html
+
+### Usage
+
+```sh
+git clone https://github.com/allyourcodebase/flex.git
+cd flex/
+zig build
+```
+
+### License
+
+- This build script is licensed under a BSD 2-Clause license
+- [flex itself is licensed under a modified BSD 2-Clause license][flex-copying]
+
+<!-- MARKDOWN LINKS -->
+
+[issue-458]: https://github.com/westes/flex/issues/458
+[flex-copying]: https://github.com/westes/flex/blob/v2.6.4/COPYING
+
+[ci-shd]: https://img.shields.io/github/actions/workflow/status/leroycep/flex/ci.yaml?branch=main&style=for-the-badge&logo=github&label=CI&labelColor=black
+[ci-url]: https://github.com/allyourcodebase/leroycep/blob/main/.github/workflows/ci.yaml
+[lc-shd]: https://img.shields.io/github/license/leroycep/flex.svg?style=for-the-badge&labelColor=black
+[lc-url]: https://github.com/allyourcodebase/leroycep/blob/main/LICENSE

build.zig

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+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.
+pub fn build(b: *std.Build) void {
+    // Standard target options allows 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 flex = b.dependency("flex-generated-src", .{});
+
+    const exe = b.addExecutable(.{
+        .name = "flex",
+        .target = target,
+        .optimize = optimize,
+    });
+
+    exe.root_module.addCMacro("VERSION", "\"v2.6.4\""); // flex version
+    exe.root_module.addCMacro("HAVE_ASSERT_H", "");
+    exe.root_module.addCMacro("HAVE_LIMITS_H", "");
+    exe.root_module.addCMacro("HAVE_NETINET_IN_H", "");
+    exe.root_module.addCMacro("M4", "m4"); // path to default m4 binary
+
+    exe.root_module.addIncludePath(flex.path("src"));
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/buf.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/ccl.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/dfa.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/ecs.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/filter.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/gen.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/main.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/misc.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/nfa.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/options.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/regex.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/scan.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/scanflags.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/scanopt.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/skel.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/sym.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/tables.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/tables_shared.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/tblcmp.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/yylex.c") });
+    exe.root_module.addCSourceFile(.{ .file = flex.path("src/parse.c") });
+    exe.root_module.link_libc = true;
+
+    // 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`).
+    b.installArtifact(exe);
+
+    // 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.
+    const run_cmd = b.addRunArtifact(exe);
+
+    // // By making the run step depend on the install 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
+    // command itself, like this: `zig build run -- arg1 arg2 etc`
+    if (b.args) |args| {
+        run_cmd.addArgs(args);
+    }
+
+    const run_step = b.step("run", "Run the app");
+    run_step.dependOn(&run_cmd.step);
+
+    const exe_unit_tests = b.addTest(.{
+        .root_source_file = b.path("src/main.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    const run_exe_unit_tests = b.addRunArtifact(exe_unit_tests);
+
+    const test_step = b.step("test", "Run unit tests");
+    test_step.dependOn(&run_exe_unit_tests.step);
+}

build.zig.zon

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+.{
+    .name = "flex",
+    // This is a [Semantic Version](https://semver.org/).
+    // In a future version of Zig it will be used for package deduplication.
+    .version = "2.6.4",
+    .dependencies = .{
+        .@"flex-generated-src" = .{
+            .url = "https://github.com/westes/flex/releases/download/v2.6.4/flex-2.6.4.tar.gz",
+            .hash = "122070327bfea3c08a1cb2dc29e24ea613e9b3a167186cb2a63813393bd6c7994998",
+        },
+    },
+    .paths = .{
+        "build.zig",
+        "build.zig.zon",
+        "LICENSE.md",
+    },
+}