removed ziglings logic from build file

1 files changed, 37 insertions, 1364 deletions

diff --git a/build.zig b/build.zig
index e8f05a2..b136583 100644
--- a/build.zig
+++ b/build.zig
@@ -1,21 +1,13 @@
 const std = @import("std");
 const builtin = @import("builtin");
-const tests = @import("test/tests.zig");
-
 const Build = std.Build;
-const CompileStep = Build.CompileStep;
-const Step = Build.Step;
-const Process = std.process;
-
-const assert = std.debug.assert;
-const join = std.fs.path.join;
 const print = std.debug.print;
 
 // When changing this version, be sure to also update README.md in two places:
 //     1) Getting Started
 //     2) Version Changes
 comptime {
-    const required_zig = "0.16.0-dev.2915";
+    const required_zig = "0.17.0-dev.607";
     const current_zig = builtin.zig_version;
     const min_zig = std.SemanticVersion.parse(required_zig) catch unreachable;
     if (current_zig.order(min_zig) == .lt) {
@@ -38,129 +30,22 @@ comptime {
     }
 }
 
-const Kind = enum {
-    /// Run the artifact as a normal executable.
-    exe,
-    /// Run the artifact as a test.
-    @"test",
-};
-
-pub const Exercise = struct {
-    /// main_file must have the format key_name.zig.
-    /// The key will be used as a shorthand to build just one example.
-    main_file: []const u8,
-
-    /// This is the desired output of the program.
-    /// A program passes if its output, excluding trailing whitespace, is equal
-    /// to this string.
-    output: []const u8,
-
-    /// This is an optional hint to give if the program does not succeed.
-    hint: ?[]const u8 = null,
-
-    /// By default, we verify output against stderr.
-    /// Set this to true to check stdout instead.
-    check_stdout: bool = false,
-
-    /// This exercise makes use of C functions.
-    /// We need to keep track of this, so we compile with libc.
-    link_libc: bool = false,
-
-    /// This exercise kind.
-    kind: Kind = .exe,
-
-    /// This exercise is not supported by the current Zig compiler.
-    skip: bool = false,
-
-    /// Hint to the user, why this has been skipped
-    skip_hint: ?[]const u8 = null,
-
-    timestamp: bool = false,
-
-    /// Returns the name of the main file with .zig stripped.
-    pub fn name(self: Exercise) []const u8 {
-        return std.fs.path.stem(self.main_file);
-    }
-
-    /// Returns the key of the main file, the string before the '_' with
-    /// "zero padding" removed.
-    /// For example, "001_hello.zig" has the key "1".
-    pub fn key(self: Exercise) []const u8 {
-        // Main file must be key_description.zig.
-        const end_index = std.mem.indexOfScalar(u8, self.main_file, '_') orelse
-            unreachable;
-
-        // Remove zero padding by advancing index past '0's.
-        var start_index: usize = 0;
-        while (self.main_file[start_index] == '0') start_index += 1;
-        return self.main_file[start_index..end_index];
-    }
-
-    /// Returns the exercise key as an integer.
-    pub fn number(self: Exercise) usize {
-        return std.fmt.parseInt(usize, self.key(), 10) catch unreachable;
-    }
-};
-
-/// Build mode.
-const Mode = enum {
-    /// Normal build mode: `zig build`
-    normal,
-    /// Named build mode: `zig build -Dn=n`
-    named,
-    /// Random build mode: `zig build -Drandom`
-    random,
-};
-
-pub const logo =
-    \\         _       _ _
-    \\     ___(_) __ _| (_)_ __   __ _ ___
-    \\    |_  | |/ _' | | | '_ \ / _' / __|
-    \\     / /| | (_| | | | | | | (_| \__ \
-    \\    /___|_|\__, |_|_|_| |_|\__, |___/
-    \\           |___/           |___/
-    \\
-    \\    "Look out! Broken programs below!"
-    \\
-    \\
-;
-
-const progress_filename = ".progress.txt";
-
+// Elrond owns the entire Ziglings logic now!
+// build.zig only builds it and forwards the chosen options as CLI flags.
+// Building just this one Run step keeps the build output readable and lets
+// Elrond iterate without the configure-phase cache getting in the way.
 pub fn build(b: *Build) !void {
     const io = b.graph.io;
 
-    if (!validate_exercises()) std.process.exit(2);
-
-    use_color_escapes = false;
-    const stderr = std.Io.File.stderr();
-    if (try stderr.supportsAnsiEscapeCodes(io)) {
-        use_color_escapes = true;
-    } else if (builtin.os.tag == .windows) {
-        if (stderr.enableAnsiEscapeCodes(io)) {
-            use_color_escapes = true;
-        } else |_| {}
-    }
-
-    if (use_color_escapes) {
-        red_text = "\x1b[31m";
-        red_bold_text = "\x1b[31;1m";
-        red_dim_text = "\x1b[31;2m";
-        green_text = "\x1b[32m";
-        bold_text = "\x1b[1m";
-        reset_text = "\x1b[0m";
-    }
-
     // Remove the standard install and uninstall steps.
     b.top_level_steps = .{};
 
-    const healed = b.option(bool, "healed", "Run exercises from patches/healed") orelse
-        false;
+    const healed = b.option(bool, "healed", "Run exercises from patches/healed") orelse false;
     const override_healed_path = b.option([]const u8, "healed-path", "Override healed path");
-    const exno: ?usize = b.option(usize, "n", "Select exercise");
-    const rand: ?bool = b.option(bool, "random", "Select random exercise");
-    const start: ?usize = b.option(usize, "s", "Start at exercise");
-    const reset: ?bool = b.option(bool, "reset", "Reset exercise progress");
+    const exno = b.option(usize, "n", "Select exercise");
+    const rand = b.option(bool, "random", "Select random exercise");
+    const start = b.option(usize, "s", "Start at exercise");
+    const reset = b.option(bool, "reset", "Reset exercise progress");
 
     const sep = std.fs.path.sep_str;
     const healed_path = if (override_healed_path) |path|
@@ -169,1254 +54,42 @@ pub fn build(b: *Build) !void {
         "patches" ++ sep ++ "healed";
     const work_path = if (healed) healed_path else "exercises";
 
-    const header_step = PrintStep.create(b, logo);
-
-    if (exno) |n| {
-        // Named build mode: verifies a single exercise.
-        if (n == 0 or n > exercises.len - 1) {
-            print("unknown exercise number: {}\n", .{n});
-            std.process.exit(2);
-        }
-        const ex = exercises[n - 1];
-
-        const zigling_step = b.step(
-            "zigling",
-            b.fmt("Check the solution of {s}", .{ex.main_file}),
-        );
-        b.default_step = zigling_step;
-        zigling_step.dependOn(&header_step.step);
-
-        const verify_step = ZiglingStep.create(b, ex, work_path, .named);
-        verify_step.step.dependOn(&header_step.step);
-
-        zigling_step.dependOn(&verify_step.step);
-
-        return;
-    }
-
-    if (rand) |_| {
-        // Random build mode: verifies one random exercise.
-        // like for 'exno' but chooses a random exercise number.
-        print("work in progress: check a random exercise\n", .{});
-
-        var prng = std.Random.DefaultPrng.init(blk: {
-            var seed: u64 = undefined;
-            io.random(std.mem.asBytes(&seed));
-            break :blk seed;
-        });
-        const rnd = prng.random();
-        const num = rnd.intRangeLessThan(usize, 0, exercises.len);
-        const ex = exercises[num];
-
-        print("random exercise: {s}\n", .{ex.main_file});
-
-        const zigling_step = b.step(
-            "random",
-            b.fmt("Check the solution of {s}", .{ex.main_file}),
-        );
-        b.default_step = zigling_step;
-        zigling_step.dependOn(&header_step.step);
-        const verify_step = ZiglingStep.create(b, ex, work_path, .random);
-        verify_step.step.dependOn(&header_step.step);
-        zigling_step.dependOn(&verify_step.step);
-        return;
-    }
-
-    if (start) |s| {
-        if (s == 0 or s > exercises.len - 1) {
-            print("unknown exercise number: {}\n", .{s});
-            std.process.exit(2);
-        }
-        const first = exercises[s - 1];
-        const ziglings_step = b.step("ziglings", b.fmt("Check ziglings starting with {s}", .{first.main_file}));
-        b.default_step = ziglings_step;
-
-        var prev_step = &header_step.step;
-        for (exercises[(s - 1)..]) |ex| {
-            const verify_stepn = ZiglingStep.create(b, ex, work_path, .normal);
-            verify_stepn.step.dependOn(prev_step);
-
-            prev_step = &verify_stepn.step;
-        }
-        ziglings_step.dependOn(prev_step);
-        return;
-    }
+    const elrond = b.addExecutable(.{
+        .name = "elrond",
+        .root_module = b.createModule(.{
+            .root_source_file = b.path("src/elrond.zig"),
+            .target = b.graph.host,
+        }),
+    });
 
+    // -Dreset is a plain file delete; no need to launch Elrond.
     if (reset) |_| {
-        std.Io.Dir.cwd().deleteFile(io, progress_filename) catch |err| {
-            switch (err) {
-                std.Io.Dir.DeleteFileError.FileNotFound => {},
-                else => {
-                    print("Unable to remove progress file, Error: {}\n", .{err});
-                    return err;
-                },
-            }
-        };
-
-        print("Progress reset, {s} removed.\n", .{progress_filename});
-        std.process.exit(0);
-    }
-
-    // Normal build mode: verifies all exercises according to the recommended
-    // order.
-    const ziglings_step = b.step("ziglings", "Check all ziglings");
-    b.default_step = ziglings_step;
-
-    var prev_step = &header_step.step;
-
-    var starting_exercise: u32 = 0;
-
-    if (std.Io.Dir.cwd().openFile(io, progress_filename, .{})) |progress_file| {
-        defer progress_file.close(io);
-
-        const progress_file_size = try progress_file.length(io);
-
-        var gpa = b.allocator;
-        const contents = try gpa.alloc(u8, progress_file_size);
-        defer gpa.free(contents);
-        var file_buffer: [1024]u8 = undefined;
-        var file_reader = progress_file.reader(io, &file_buffer);
-        // try file_reader.interface.readSliceAll(contents);
-        const bytes_read = try file_reader.interface.readSliceShort(contents);
-        if (bytes_read != progress_file_size) {
-            return error.UnexpectedEOF;
-        }
-
-        const trimmed_contents = std.mem.trim(u8, contents, "\r\n");
-        starting_exercise = try std.fmt.parseInt(u32, trimmed_contents, 10);
-    } else |err| {
-        switch (err) {
-            std.Io.File.OpenError.FileNotFound => {
-                // This is fine, may be the first time tests are run or progress have been reset
-            },
+        std.Io.Dir.cwd().deleteFile(io, ".progress.txt") catch |err| switch (err) {
+            error.FileNotFound => {},
             else => {
-                print("Unable to open {s}: {}\n", .{ progress_filename, err });
+                print("Unable to remove progress file: {}\n", .{err});
                 return err;
             },
-        }
-    }
-
-    for (exercises) |ex| {
-        if (starting_exercise < ex.number()) {
-            const verify_stepn = ZiglingStep.create(b, ex, work_path, .normal);
-            verify_stepn.step.dependOn(prev_step);
-
-            prev_step = &verify_stepn.step;
-        }
-    }
-    ziglings_step.dependOn(prev_step);
-
-    const test_step = b.step("test", "Run all the tests");
-    test_step.dependOn(tests.addCliTests(b, &exercises));
-}
-
-var use_color_escapes = false;
-var red_text: []const u8 = "";
-var red_bold_text: []const u8 = "";
-var red_dim_text: []const u8 = "";
-var green_text: []const u8 = "";
-var bold_text: []const u8 = "";
-var reset_text: []const u8 = "";
-
-const ZiglingStep = struct {
-    step: Step,
-    exercise: Exercise,
-    work_path: []const u8,
-    mode: Mode,
-
-    pub fn create(
-        b: *Build,
-        exercise: Exercise,
-        work_path: []const u8,
-        mode: Mode,
-    ) *ZiglingStep {
-        const self = b.allocator.create(ZiglingStep) catch @panic("OOM");
-        self.* = .{
-            .step = Step.init(.{
-                .id = .custom,
-                .name = exercise.main_file,
-                .owner = b,
-                .makeFn = make,
-            }),
-            .exercise = exercise,
-            .work_path = work_path,
-            .mode = mode,
         };
-        return self;
-    }
-
-    fn printProgress(num: usize, max: usize) void {
-        const bar_width: u32 = 60;
-
-        const filled_len_u64 = (@as(u64, num) * bar_width) / max;
-        const filled_len = @as(u32, @intCast(filled_len_u64));
-
-        var bar_buf: [bar_width]u8 = undefined;
-
-        for (0..bar_width) |n| {
-            const ord = std.math.order(n, filled_len);
-            bar_buf[n] = switch (ord) {
-                .lt => '#',
-                .eq => '>',
-                .gt => '-',
-            };
-        }
-
-        std.debug.print("\rProgress: [{s}]  {d}/{d}\n\n", .{ &bar_buf, num, max });
-    }
-
-    fn make(step: *Step, options: Step.MakeOptions) !void {
-        // NOTE: Using exit code 2 will prevent the Zig compiler to print the message:
-        // "error: the following build command failed with exit code 1:..."
-        const self: *ZiglingStep = @alignCast(@fieldParentPtr("step", step));
-
-        if (self.exercise.skip) {
-            print("Skipping {s}", .{self.exercise.main_file});
-
-            if (self.exercise.skip_hint) |hint|
-                print("\n{s}Reason: {s}{s}\n", .{ bold_text, hint, reset_text });
-
-            print("\n\n", .{});
-            return;
-        }
-
-        // Progess
-        printProgress(self.exercise.number(), exercises.len - 1);
-
-        const exe_path = self.compile(options.progress_node) catch {
-            self.printErrors();
-
-            if (self.exercise.hint) |hint|
-                print("\n{s}Ziglings hint: {s}{s}", .{ bold_text, hint, reset_text });
-
-            self.help();
-            std.process.exit(2);
-        };
-
-        self.run(exe_path, options.progress_node) catch {
-            self.printErrors();
-
-            if (self.exercise.hint) |hint|
-                print("\n{s}Ziglings hint: {s}{s}", .{ bold_text, hint, reset_text });
-
-            self.help();
-            std.process.exit(2);
-        };
-
-        // Print possible warning/debug messages.
-        self.printErrors();
-    }
-
-    fn run(self: *ZiglingStep, exe_path: []const u8, _: std.Progress.Node) !void {
-        resetLine();
-        const b = self.step.owner;
-        const gpa = b.allocator;
-        const io = b.graph.io;
-
-        print("Checking: {s}\n", .{self.exercise.main_file});
-
-        // Allow up to 1 MB of stdout capture.
-        const max_output_bytes = 1 * 1024 * 1024;
-
-        const result = Process.run(gpa, io, .{
-            .argv = &.{exe_path},
-            .cwd = .{ .path = b.build_root.path.? },
-            .stdout_limit = .limited(max_output_bytes),
-        }) catch |err| {
-            return self.step.fail("unable to spawn {s}: {s}", .{
-                exe_path, @errorName(err),
-            });
-        };
-
-        switch (self.exercise.kind) {
-            .exe => return self.check_output(result),
-            .@"test" => return self.check_test(result),
-        }
-    }
-
-    fn check_output(self: *ZiglingStep, result: Process.RunResult) !void {
-        const b = self.step.owner;
-        const gpa = b.allocator;
-        const io = b.graph.io;
-
-        // Make sure it exited cleanly.
-        switch (result.term) {
-            .exited => |code| {
-                if (code != 0) {
-                    return self.step.fail("{s} exited with error code {d} (expected {})", .{
-                        self.exercise.main_file, code, 0,
-                    });
-                }
-            },
-            else => {
-                return self.step.fail("{s} terminated unexpectedly", .{
-                    self.exercise.main_file,
-                });
-            },
-        }
-
-        const raw_output = if (self.exercise.check_stdout)
-            result.stdout
-        else
-            result.stderr;
-
-        // NOTE: exercise.output can never contain a CR character.
-        // See https://ziglang.org/documentation/master/#Source-Encoding.
-        const output = trimLines(gpa, raw_output) catch @panic("OOM");
-
-        // Validate the output.
-        var exercise_output = self.exercise.output;
-
-        // Insert timestamp for exercise 85
-        if (self.exercise.timestamp) {
-
-            // Compare timestamp from exercise with now, diff < 5 seconds is valid
-            var ts_buf: [20]u8 = undefined;
-            const ts_slice = output[14..24];
-            const ts_value = try std.fmt.parseInt(i64, ts_slice, 10);
-            const ts_build = std.Io.Timestamp.now(io, .real).toSeconds();
-            const ts_diff = @abs(ts_build - ts_value);
-            const timestamp = std.fmt.bufPrint(&ts_buf, "{}", .{if (ts_diff < 5) ts_value else ts_build}) catch unreachable;
-
-            // Insert timestamp into check string
-            var buf: [100]u8 = undefined;
-            const prefix_len = 14;
-            const placeholder_len = 11;
-
-            @memcpy(buf[0..prefix_len], exercise_output[0..prefix_len]);
-            @memcpy(buf[prefix_len..][0..timestamp.len], timestamp);
-            const suffix = exercise_output[prefix_len + placeholder_len ..];
-            const suffix_dest_start = prefix_len + timestamp.len;
-            @memcpy(buf[suffix_dest_start..][0..suffix.len], suffix);
-
-            const total_len = prefix_len + timestamp.len + suffix.len;
-            exercise_output = buf[0..total_len];
-        }
-
-        if (!std.mem.eql(u8, output, exercise_output)) {
-            const red = red_bold_text;
-            const reset = reset_text;
-
-            // Override the coloring applied by the printError method.
-            // NOTE: the first red and the last reset are not necessary, they
-            // are here only for alignment.
-            return self.step.fail(
-                \\
-                \\{s}========= expected this output: =========={s}
-                \\{s}
-                \\{s}========= but found: ====================={s}
-                \\{s}
-                \\{s}=========================================={s}
-            , .{ red, reset, exercise_output, red, reset, output, red, reset });
-        }
-
-        const progress = try std.fmt.allocPrint(gpa, "{d}", .{self.exercise.number()});
-        defer gpa.free(progress);
-
-        const file = try std.Io.Dir.cwd().createFile(
-            io,
-            progress_filename,
-            .{ .read = true, .truncate = true },
-        );
-        defer file.close(io);
-
-        try file.writeStreamingAll(io, progress);
-        try file.sync(io);
-
-        print("{s}PASSED:\n{s}{s}\n\n", .{ green_text, output, reset_text });
-    }
-
-    fn check_test(self: *ZiglingStep, result: Process.RunResult) !void {
-        switch (result.term) {
-            .exited => |code| {
-                if (code != 0) {
-                    // The test failed.
-                    const stderr = std.mem.trimEnd(u8, result.stderr, " \r\n");
-
-                    return self.step.fail("\n{s}", .{stderr});
-                }
-            },
-            else => {
-                return self.step.fail("{s} terminated unexpectedly", .{
-                    self.exercise.main_file,
-                });
-            },
-        }
-
-        print("{s}PASSED{s}\n\n", .{ green_text, reset_text });
-    }
-
-    fn compile(self: *ZiglingStep, prog_node: std.Progress.Node) ![]const u8 {
-        print("Compiling: {s}\n", .{self.exercise.main_file});
-
-        const b = self.step.owner;
-        const gpa = b.allocator;
-        const exercise_path = self.exercise.main_file;
-        const path = join(gpa, &.{ self.work_path, exercise_path }) catch
-            @panic("OOM");
-
-        var zig_args = std.ArrayList([]const u8).initCapacity(gpa, 10) catch @panic("OOM");
-        defer zig_args.deinit(gpa);
-
-        zig_args.append(gpa, b.graph.zig_exe) catch @panic("OOM");
-
-        const cmd = switch (self.exercise.kind) {
-            .exe => "build-exe",
-            .@"test" => "test",
-        };
-        zig_args.append(gpa, cmd) catch @panic("OOM");
-
-        // Enable C support for exercises that use C functions.
-        if (self.exercise.link_libc) {
-            zig_args.append(gpa, "-lc") catch @panic("OOM");
-            zig_args.append(gpa, "-fllvm") catch @panic("OOM");
-        }
-
-        if (b.reference_trace) |rt| {
-            zig_args.append(gpa, b.fmt("-freference-trace={}", .{rt})) catch @panic("OOM");
-        }
-
-        zig_args.append(gpa, b.pathFromRoot(path)) catch @panic("OOM");
-
-        zig_args.append(gpa, "--cache-dir") catch @panic("OOM");
-        zig_args.append(gpa, b.pathFromRoot(b.cache_root.path.?)) catch @panic("OOM");
-
-        zig_args.append(gpa, "--listen=-") catch @panic("OOM");
-
-        //
-        // NOTE: After many changes in zig build system, we need to create the cache path manually.
-        // See https://github.com/ziglang/zig/pull/21115
-        // Maybe there is a better way (in the future).
-        const exe_dir = try self.step.evalZigProcess(zig_args.items, prog_node, false, null, gpa);
-        const exe_name = switch (self.exercise.kind) {
-            .exe => self.exercise.name(),
-            .@"test" => "test",
-        };
-        const sep = std.Io.Dir.path.sep_str;
-        const root_path = exe_dir.?.root_dir.path.?;
-        const sub_path = exe_dir.?.subPathOrDot();
-        const exe_path = b.fmt("{s}{s}{s}{s}{s}", .{ root_path, sep, sub_path, sep, exe_name });
-
-        return exe_path;
-    }
-
-    fn help(self: *ZiglingStep) void {
-        const b = self.step.owner;
-        const key = self.exercise.key();
-        const path = self.exercise.main_file;
-
-        const cmd = switch (self.mode) {
-            .normal => "zig build",
-            .named => b.fmt("zig build -Dn={s}", .{key}),
-            .random => "zig build -Drandom",
-        };
-
-        print("\n{s}Edit exercises/{s} and run '{s}' again.{s}\n", .{
-            red_bold_text, path, cmd, reset_text,
-        });
-    }
-
-    fn printErrors(self: *ZiglingStep) void {
-        resetLine();
-        const b = self.step.owner;
-        const io = b.graph.io;
-
-        // Display error/warning messages.
-        if (self.step.result_error_msgs.items.len > 0) {
-            for (self.step.result_error_msgs.items) |msg| {
-                print("{s}error: {s}{s}{s}{s}\n", .{
-                    red_bold_text, reset_text, red_dim_text, msg, reset_text,
-                });
-            }
-        }
-
-        // Render compile errors at the bottom of the terminal.
-        // TODO: use the same ttyconf from the builder.
-        const color: std.zig.Color = if (use_color_escapes)
-            .on
-        else
-            .off;
-        if (self.step.result_error_bundle.errorMessageCount() > 0) {
-            self.step.result_error_bundle.renderToStderr(io, .{}, color) catch |err| {
-                print("{}\n", .{err});
-                return;
-            };
-        }
-    }
-};
-
-/// Clears the entire line and move the cursor to column zero.
-/// Used for clearing the compiler and build_runner progress messages.
-fn resetLine() void {
-    if (use_color_escapes) print("{s}", .{"\x1b[2K\r"});
-}
-
-/// Removes trailing whitespace for each line in buf, also ensuring that there
-/// are no trailing LF characters at the end.
-pub fn trimLines(gpa: std.mem.Allocator, buf: []const u8) ![]const u8 {
-    var list = try std.ArrayList(u8).initCapacity(gpa, buf.len);
-    errdefer list.deinit(gpa);
-
-    var iter = std.mem.splitSequence(u8, buf, " \n");
-    while (iter.next()) |line| {
-        // TODO: trimming CR characters is probably not necessary.
-        const data = std.mem.trimEnd(u8, line, " \r");
-        try list.appendSlice(gpa, data);
-        try list.append(gpa, '\n');
-    }
-
-    // Calls deinit()
-    const result = try list.toOwnedSlice(gpa);
-
-    // Remove the trailing LF character, that is always present in the exercise output.
-    return std.mem.trimEnd(u8, result, "\n");
-}
-
-/// Prints a message to stderr.
-const PrintStep = struct {
-    step: Step,
-    message: []const u8,
-
-    pub fn create(owner: *Build, message: []const u8) *PrintStep {
-        const self = owner.allocator.create(PrintStep) catch @panic("OOM");
-        self.* = .{
-            .step = Step.init(.{
-                .id = .custom,
-                .name = "print",
-                .owner = owner,
-                .makeFn = make,
-            }),
-            .message = message,
-        };
-
-        return self;
-    }
-
-    fn make(step: *Step, _: Step.MakeOptions) !void {
-        const self: *PrintStep = @alignCast(@fieldParentPtr("step", step));
-        print("{s}", .{self.message});
+        print("Progress reset, .progress.txt removed.\n", .{});
+        const noop = b.step("ziglings", "Reset progress");
+        b.default_step = noop;
+        return;
     }
-};
-
-/// Checks that each exercise number, excluding the last, forms the sequence
-/// `[1, exercise.len)`.
-///
-/// Additionally check that the output field lines doesn't have trailing whitespace.
-fn validate_exercises() bool {
-    // Don't use the "multi-object for loop" syntax, in order to avoid a syntax
-    // error with old Zig compilers.
-    var i: usize = 0;
-    for (exercises[0..]) |ex| {
-        const exno = ex.number();
-        const last = 999;
-        i += 1;
-
-        if (exno != i and exno != last) {
-            print("exercise {s} has an incorrect number: expected {}, got {s}\n", .{
-                ex.main_file, i, ex.key(),
-            });
-
-            return false;
-        }
-
-        var iter = std.mem.splitScalar(u8, ex.output, '\n');
-        while (iter.next()) |line| {
-            const output = std.mem.trimEnd(u8, line, " \r");
-            if (output.len != line.len) {
-                print("exercise {s} output field lines have trailing whitespace\n", .{
-                    ex.main_file,
-                });
 
-                return false;
-            }
-        }
+    const run = b.addRunArtifact(elrond);
+    run.addArg(b.fmt("--zig={s}", .{b.graph.zig_exe}));
+    run.addArg(b.fmt("--work-path={s}", .{work_path}));
 
-        if (!std.mem.endsWith(u8, ex.main_file, ".zig")) {
-            print("exercise {s} is not a zig source file\n", .{ex.main_file});
-
-            return false;
-        }
+    if (exno) |n| {
+        run.addArg(b.fmt("--only={d}", .{n}));
+    } else if (rand) |_| {
+        run.addArg("--random");
+    } else if (start) |s| {
+        run.addArg(b.fmt("--start={d}", .{s}));
     }
 
-    return true;
+    const ziglings_step = b.step("ziglings", "Run ziglings");
+    ziglings_step.dependOn(&run.step);
+    b.default_step = ziglings_step;
 }
-
-const exercises = [_]Exercise{
-    .{
-        .main_file = "001_hello.zig",
-        .output = "Hello world!",
-        .hint =
-        \\DON'T PANIC!
-        \\Read the compiler messages above. (Something about 'main'?)
-        \\Open up the source file as noted below and read the comments.
-        \\
-        \\(Hints like these will occasionally show up, but for the
-        \\most part, you'll be taking directions from the Zig
-        \\compiler itself.)
-        \\
-        , // pay attention to the comma
-    },
-    .{
-        .main_file = "002_std.zig",
-        .output = "Standard Library.",
-    },
-    .{
-        .main_file = "003_assignment.zig",
-        .output = "55 314159 -11",
-        .hint = "There are three mistakes in this one!",
-    },
-    .{
-        .main_file = "004_arrays.zig",
-        .output = "First: 2, Fourth: 7, Length: 8",
-        .hint = "There are two things to complete here.",
-    },
-    .{
-        .main_file = "005_arrays2.zig",
-        .output = "LEET: 1337, Bits: 100110011001",
-        .hint = "Fill in the two arrays.",
-    },
-    .{
-        .main_file = "006_strings.zig",
-        .output = "d=d Major Tom",
-        .hint = "Each '???' needs something filled in.",
-    },
-    .{
-        .main_file = "007_strings2.zig",
-        .output =
-        \\Ziggy played guitar
-        \\Jamming good with Andrew Kelley
-        \\And the Spiders from Mars
-        , // pay attention to the comma
-        .hint = "Please fix the lyrics!",
-    },
-    .{
-        .main_file = "008_quiz.zig",
-        .output = "Program in Zig!",
-        .hint = "See if you can fix the program!",
-    },
-    .{
-        .main_file = "009_if.zig",
-        .output = "Foo is 42!",
-    },
-    .{
-        .main_file = "010_if2.zig",
-        .output = "With the discount, the price is $17.",
-    },
-    .{
-        .main_file = "011_while.zig",
-        .output = "2 4 8 16 32 64 128 256 512 n=1024",
-        .hint = "You probably want a 'less than' condition.",
-    },
-    .{
-        .main_file = "012_while2.zig",
-        .output = "2 4 8 16 32 64 128 256 512 n=1024",
-        .hint = "It might help to look back at the previous exercise.",
-    },
-    .{
-        .main_file = "013_while3.zig",
-        .output = "1 2 4 7 8 11 13 14 16 17 19",
-    },
-    .{
-        .main_file = "014_while4.zig",
-        .output = "n=4",
-    },
-    .{
-        .main_file = "015_for.zig",
-        .output = "A Dramatic Story: :-)  :-)  :-(  :-|  :-)  The End.",
-    },
-    .{
-        .main_file = "016_for2.zig",
-        .output = "The value of bits '1101': 13.",
-    },
-    .{
-        .main_file = "017_quiz2.zig",
-        .output = "1, 2, Fizz, 4, Buzz, Fizz, 7, 8, Fizz, Buzz, 11, Fizz, 13, 14, FizzBuzz, 16,",
-        .hint = "This is a famous game!",
-    },
-    .{
-        .main_file = "018_functions.zig",
-        .output = "Answer to the Ultimate Question: 42",
-        .hint = "Can you help write the function?",
-    },
-    .{
-        .main_file = "019_functions2.zig",
-        .output = "Powers of two: 2 4 8 16",
-    },
-    .{
-        .main_file = "020_quiz3.zig",
-        .output = "32 64 128 256",
-        .hint = "Unexpected pop quiz! Help!",
-    },
-    .{
-        .main_file = "021_errors.zig",
-        .output = "2<4. 3<4. 4=4. 5>4. 6>4.",
-        .hint = "What's the deal with fours?",
-    },
-    .{
-        .main_file = "022_errors2.zig",
-        .output = "I compiled!",
-        .hint = "Get the error union type right to allow this to compile.",
-    },
-    .{
-        .main_file = "023_errors3.zig",
-        .output = "a=64, b=22",
-    },
-    .{
-        .main_file = "024_errors4.zig",
-        .output = "a=20, b=14, c=10",
-    },
-    .{
-        .main_file = "025_errors5.zig",
-        .output = "a=0, b=19, c=0",
-    },
-    .{
-        .main_file = "026_hello2.zig",
-        .output = "Hello world!",
-        .hint = "Try using a try!",
-        .check_stdout = true,
-    },
-    .{
-        .main_file = "027_defer.zig",
-        .output = "One Two",
-    },
-    .{
-        .main_file = "028_defer2.zig",
-        .output = "(Goat) (Cat) (Dog) (Dog) (Goat) (Unknown) done.",
-    },
-    .{
-        .main_file = "029_errdefer.zig",
-        .output = "Getting number...got 5. Getting number...failed!",
-    },
-    .{
-        .main_file = "030_switch.zig",
-        .output = "ZIG?",
-    },
-    .{
-        .main_file = "031_switch2.zig",
-        .output = "ZIG!",
-    },
-    .{
-        .main_file = "032_unreachable.zig",
-        .output = "1 2 3 9 8 7",
-    },
-    .{
-        .main_file = "033_iferror.zig",
-        .output = "2<4. 3<4. 4=4. 5>4. 6>4.",
-        .hint = "Seriously, what's the deal with fours?",
-    },
-    .{
-        .main_file = "034_quiz4.zig",
-        .output = "my_num=42",
-        .hint = "Can you make this work?",
-        .check_stdout = true,
-    },
-    .{
-        .main_file = "035_enums.zig",
-        .output = "1 2 3 9 8 7",
-        .hint = "This problem seems familiar...",
-    },
-    .{
-        .main_file = "036_enums2.zig",
-        .output =
-        \\<p>
-        \\  <span style="color: #ff0000">Red</span>
-        \\  <span style="color: #00ff00">Green</span>
-        \\  <span style="color: #0000ff">Blue</span>
-        \\</p>
-        , // pay attention to the comma
-        .hint = "I'm feeling blue about this.",
-    },
-    .{
-        .main_file = "037_structs.zig",
-        .output = "Your wizard has 90 health and 25 gold.",
-    },
-    .{
-        .main_file = "038_structs2.zig",
-        .output =
-        \\Character 1 - G:20 H:100 XP:10
-        \\Character 2 - G:10 H:100 XP:20
-        , // pay attention to the comma
-    },
-    .{
-        .main_file = "039_pointers.zig",
-        .output = "num1: 5, num2: 5",
-        .hint = "Pointers aren't so bad.",
-    },
-    .{
-        .main_file = "040_pointers2.zig",
-        .output = "a: 12, b: 12",
-    },
-    .{
-        .main_file = "041_pointers3.zig",
-        .output = "foo=6, bar=11",
-    },
-    .{
-        .main_file = "042_pointers4.zig",
-        .output = "num: 5, more_nums: 1 1 5 1",
-    },
-    .{
-        .main_file = "043_pointers5.zig",
-        .output =
-        \\Wizard (G:10 H:100 XP:20)
-        \\  Mentor: Wizard (G:10000 H:100 XP:2340)
-        , // pay attention to the comma
-    },
-    .{
-        .main_file = "044_quiz5.zig",
-        .output = "Elephant A. Elephant B. Elephant C.",
-        .hint = "Oh no! We forgot Elephant B!",
-    },
-    .{
-        .main_file = "045_optionals.zig",
-        .output = "The Ultimate Answer: 42.",
-    },
-    .{
-        .main_file = "046_optionals2.zig",
-        .output = "Elephant A. Elephant B. Elephant C.",
-        .hint = "Elephants again!",
-    },
-    .{
-        .main_file = "047_methods.zig",
-        .output = "5 aliens. 4 aliens. 1 aliens. 0 aliens. Earth is saved!",
-        .hint = "Use the heat ray. And the method!",
-    },
-    .{
-        .main_file = "048_methods2.zig",
-        .output = "A  B  C",
-        .hint = "This just needs one little fix.",
-    },
-    .{
-        .main_file = "049_quiz6.zig",
-        .output = "A  B  C  Cv Bv Av",
-        .hint = "Now you're writing Zig!",
-    },
-    .{
-        .main_file = "050_no_value.zig",
-        .output = "That is not dead which can eternal lie / And with strange aeons even death may die.",
-    },
-    .{
-        .main_file = "051_values.zig",
-        .output = "1:false!. 2:true!. 3:true!. XP before:0, after:200.",
-    },
-    .{
-        .main_file = "052_slices.zig",
-        .output =
-        \\Hand1: A 4 K 8
-        \\Hand2: 5 2 Q J
-        , // pay attention to the comma
-    },
-    .{
-        .main_file = "053_slices2.zig",
-        .output = "'all your base are belong to us.' 'for great justice.'",
-    },
-    .{
-        .main_file = "054_manypointers.zig",
-        .output = "Memory is a resource.",
-    },
-    .{
-        .main_file = "055_unions.zig",
-        .output = "Insect report! Ant alive is: true. Bee visited 15 flowers.",
-    },
-    .{
-        .main_file = "056_unions2.zig",
-        .output = "Insect report! Ant alive is: true. Bee visited 16 flowers.",
-    },
-    .{
-        .main_file = "057_unions3.zig",
-        .output = "Insect report! Ant alive is: true. Bee visited 17 flowers.",
-    },
-    .{
-        .main_file = "058_quiz7.zig",
-        .output = "Archer's Point--2->Bridge--1->Dogwood Grove--3->Cottage--2->East Pond--1->Fox Pond",
-        .hint = "This is the biggest program we've seen yet. But you can do it!",
-    },
-    .{
-        .main_file = "059_integers.zig",
-        .output = "Zig is cool.",
-    },
-    .{
-        .main_file = "060_floats.zig",
-        .output = "Shuttle liftoff weight: 2.032e3 metric tons",
-    },
-    .{
-        .main_file = "061_coercions.zig",
-        .output = "Letter: A",
-    },
-    .{
-        .main_file = "062_loop_expressions.zig",
-        .output = "Current language: Zig",
-        .hint = "Surely the current language is 'Zig'!",
-    },
-    .{
-        .main_file = "063_labels.zig",
-        .output = "Enjoy your Cheesy Chili!",
-    },
-    .{
-        .main_file = "064_builtins.zig",
-        .output = "1101 + 0101 = 0010 (true). Without overflow: 00010010. Furthermore, 11110000 backwards is 00001111.",
-    },
-    .{
-        .main_file = "065_builtins2.zig",
-        .output = "A Narcissus loves all Narcissuses. He has room in his heart for: me myself.",
-    },
-    .{
-        .main_file = "066_comptime.zig",
-        .output = "Immutable: 12345, 987.654; Mutable: 54321, 456.789; Types: comptime_int, comptime_float, u32, f32",
-        .hint = "It may help to read this one out loud to your favorite stuffed animal until it sinks in completely.",
-    },
-    .{
-        .main_file = "067_comptime2.zig",
-        .output = "A BB CCC DDDD",
-    },
-    .{
-        .main_file = "068_comptime3.zig",
-        .output =
-        \\Minnow (1:32, 4 x 2)
-        \\Shark (1:16, 8 x 5)
-        \\Whale (1:1, 143 x 95)
-        ,
-    },
-    .{
-        .main_file = "069_comptime4.zig",
-        .output = "s1={ 1, 2, 3 }, s2={ 1, 2, 3, 4, 5 }, s3={ 1, 2, 3, 4, 5, 6, 7 }",
-    },
-    .{
-        .main_file = "070_comptime5.zig",
-        .output =
-        \\"Quack." ducky1: true, "Squeek!" ducky2: true, ducky3: false
-        ,
-        .hint = "Have you kept the wizard hat on?",
-    },
-    .{
-        .main_file = "071_comptime6.zig",
-        .output = "Narcissus has room in his heart for: me myself.",
-    },
-    .{
-        .main_file = "072_comptime7.zig",
-        .output = "26",
-    },
-    .{
-        .main_file = "073_comptime8.zig",
-        .output = "My llama value is 25.",
-    },
-    .{
-        .main_file = "074_comptime9.zig",
-        .output = "MouseLlama joins the crew!",
-    },
-    .{
-        .main_file = "075_quiz8.zig",
-        .output = "Archer's Point--2->Bridge--1->Dogwood Grove--3->Cottage--2->East Pond--1->Fox Pond",
-        .hint = "Roll up those sleeves. You get to WRITE some code for this one.",
-    },
-    .{
-        .main_file = "076_sentinels.zig",
-        .output = "Array:123056. Many-item pointer:123.",
-    },
-    .{
-        .main_file = "077_sentinels2.zig",
-        .output = "Weird Data!",
-    },
-    .{
-        .main_file = "078_sentinels3.zig",
-        .output = "Weird Data!",
-    },
-    .{
-        .main_file = "079_quoted_identifiers.zig",
-        .output = "Sweet freedom: 55, false.",
-        .hint = "Help us, Zig Programmer, you're our only hope!",
-    },
-    .{
-        .main_file = "080_anonymous_structs.zig",
-        .output = "[Circle(i32): 25,70,15] [Circle(f32): 25.2,71.0,15.7]",
-    },
-    .{
-        .main_file = "081_anonymous_structs2.zig",
-        .output = "x:205 y:187 radius:12",
-    },
-    .{
-        .main_file = "082_anonymous_structs3.zig",
-        .output =
-        \\"0"(bool):true "1"(bool):false "2"(i32):42 "3"(f32):3.141592
-        , // pay attention to the comma
-        .hint = "This one is a challenge! But you have everything you need.",
-    },
-    .{
-        .main_file = "083_anonymous_lists.zig",
-        .output = "I say hello!",
-    },
-    .{
-        .main_file = "084_interfaces.zig",
-        .output =
-        \\=== Doctor Zoraptera's Insect Report ===
-        \\Ant is alive.
-        \\Bee visited 17 flowers.
-        \\Grasshopper hopped 32 meters.
-        , // pay attention to the comma
-    },
-
-    // Skipped because of https://github.com/ratfactor/ziglings/issues/163
-    // direct link: https://github.com/ziglang/zig/issues/6025
-    .{
-        .main_file = "085_async.zig",
-        .output = "Current time: <timestamp>s since epoch",
-        .timestamp = true,
-    },
-    .{
-        .main_file = "086_async2.zig",
-        .output = "Computing... The answer is: 42",
-    },
-    .{
-        .main_file = "087_async3.zig",
-        .output =
-        \\1 + 2 = 3
-        \\6 * 7 = 42
-        \\Total: 45
-        , // pay attention to the comma
-    },
-    .{
-        .main_file = "088_async4.zig",
-        .output =
-        \\Task 1 done.
-        \\Task 2 done.
-        \\Task 3 done.
-        \\All tasks finished!
-        , // pay attention to the comma
-    },
-    .{
-        .main_file = "089_async5.zig",
-        .output =
-        \\Starting long computation...
-        \\Canceling slow task...
-        \\Task was canceled, cleaning up.
-        \\Task returned: 0
-        , // pay attention to the comma
-    },
-    .{
-        .main_file = "090_async6.zig",
-        .output = "Hare: I'm fast!",
-    },
-    .{
-        .main_file = "091_async7.zig",
-        .output = "Counter: 400",
-    },
-    .{
-        .main_file = "092_async8.zig",
-        .output = "Sum of 1..10 = 55",
-    },
-    .{
-        .main_file = "093_async9.zig",
-        .output = "Worker 1 found signal start over threshold at index 12!",
-    },
-    .{
-        .main_file = "094_async10.zig",
-        .output =
-        \\Starting critical section...
-        \\Critical section completed safely.
-        \\Task result: All data saved.
-        , // pay attention to the comma
-    },
-    .{
-        .main_file = "095_quiz_async.zig",
-        .output =
-        \\=== Doctor Zoraptera's Garden Report ===
-        \\Temperature : 23C
-        \\Humidity    : 63%
-        \\Wind        : 13 km/h
-        \\Readings    : 9
-        \\Bee-friendly conditions! Expect high pollination.
-        , // pay attention to the comma
-    },
-    .{
-        .main_file = "096_hello_c.zig",
-        .output = "Hello C from Zig! - C result is 17 chars written.",
-        .link_libc = true,
-        .skip = true,
-        .skip_hint = "Skipped until we have found a solution for the removed '@cImport'",
-    },
-    .{
-        .main_file = "097_c_math.zig",
-        .output = "The normalized angle of 765.2 degrees is 45.2 degrees.",
-        .link_libc = true,
-        .skip = true,
-        .skip_hint = "Skipped until we have found a solution for the removed '@cImport'",
-    },
-    .{
-        .main_file = "098_for3.zig",
-        .output = "1 2 4 7 8 11 13 14 16 17 19\n1 2 3 4 5 6 7 8 9 10 11 12 13 14 15",
-    },
-    .{
-        .main_file = "099_memory_allocation.zig",
-        .output = "Running Average: 0.30 0.25 0.20 0.18 0.22",
-    },
-    .{
-        .main_file = "100_bit_manipulation.zig",
-        .output = "x = 1011; y = 1101",
-    },
-    .{
-        .main_file = "101_bit_manipulation2.zig",
-        .output = "Is this a pangram? true!",
-    },
-    .{
-        .main_file = "102_formatting.zig",
-        .output =
-        \\
-        \\ X |  1   2   3   4   5   6   7   8   9  10  11  12  13  14  15
-        \\---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
-        \\ 1 |  1   2   3   4   5   6   7   8   9  10  11  12  13  14  15
-        \\
-        \\ 2 |  2   4   6   8  10  12  14  16  18  20  22  24  26  28  30
-        \\
-        \\ 3 |  3   6   9  12  15  18  21  24  27  30  33  36  39  42  45
-        \\
-        \\ 4 |  4   8  12  16  20  24  28  32  36  40  44  48  52  56  60
-        \\
-        \\ 5 |  5  10  15  20  25  30  35  40  45  50  55  60  65  70  75
-        \\
-        \\ 6 |  6  12  18  24  30  36  42  48  54  60  66  72  78  84  90
-        \\
-        \\ 7 |  7  14  21  28  35  42  49  56  63  70  77  84  91  98 105
-        \\
-        \\ 8 |  8  16  24  32  40  48  56  64  72  80  88  96 104 112 120
-        \\
-        \\ 9 |  9  18  27  36  45  54  63  72  81  90  99 108 117 126 135
-        \\
-        \\10 | 10  20  30  40  50  60  70  80  90 100 110 120 130 140 150
-        \\
-        \\11 | 11  22  33  44  55  66  77  88  99 110 121 132 143 154 165
-        \\
-        \\12 | 12  24  36  48  60  72  84  96 108 120 132 144 156 168 180
-        \\
-        \\13 | 13  26  39  52  65  78  91 104 117 130 143 156 169 182 195
-        \\
-        \\14 | 14  28  42  56  70  84  98 112 126 140 154 168 182 196 210
-        \\
-        \\15 | 15  30  45  60  75  90 105 120 135 150 165 180 195 210 225
-        ,
-    },
-    .{
-        .main_file = "103_for4.zig",
-        .output = "Arrays match!",
-    },
-    .{
-        .main_file = "104_for5.zig",
-        .output =
-        \\1. Wizard (Gold: 25, XP: 40)
-        \\2. Bard (Gold: 11, XP: 17)
-        \\3. Bard (Gold: 5, XP: 55)
-        \\4. Warrior (Gold: 7392, XP: 21)
-        , // pay attention to the comma
-    },
-    .{
-        .main_file = "105_testing.zig",
-        .output = "",
-        .kind = .@"test",
-    },
-    .{
-        .main_file = "106_tokenization.zig",
-        .output =
-        \\My
-        \\name
-        \\is
-        \\Ozymandias
-        \\King
-        \\of
-        \\Kings
-        \\Look
-        \\on
-        \\my
-        \\Works
-        \\ye
-        \\Mighty
-        \\and
-        \\despair
-        \\This little poem has 15 words!
-        , // pay attention to the comma
-    },
-    .{
-        .main_file = "107_threading.zig",
-        .output =
-        \\Starting work...
-        \\thread 1: started.
-        \\thread 2: started.
-        \\thread 3: started.
-        \\Some weird stuff, after starting the threads.
-        \\thread 2: finished.
-        \\thread 1: finished.
-        \\thread 3: finished.
-        \\Zig is cool!
-        , // pay attention to the comma
-    },
-    .{
-        .main_file = "108_threading2.zig",
-        .output = "PI ≈ 3.14159265",
-    },
-    .{
-        .main_file = "109_files.zig",
-        .output = "Successfully wrote 18 bytes.",
-    },
-    .{
-        .main_file = "110_files2.zig",
-        .output =
-        \\AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
-        \\Successfully Read 18 bytes: It's zigling time!
-        , // pay attention to the comma
-    },
-    .{
-        .main_file = "111_labeled_switch.zig",
-        .output = "The pull request has been merged.",
-    },
-    .{
-        .main_file = "112_vectors.zig",
-        .output =
-        \\Max difference (old fn): 0.014
-        \\Max difference (new fn): 0.014
-        , // pay attention to the comma
-    },
-    .{ .main_file = "113_quiz9.zig", .output =
-    \\Toggle pins with XOR on PORTB
-    \\-----------------------------
-    \\  1100 // (initial state of PORTB)
-    \\^ 0101 // (bitmask)
-    \\= 1001
-    \\
-    \\  1100 // (initial state of PORTB)
-    \\^ 0011 // (bitmask)
-    \\= 1111
-    \\
-    \\Set pins with OR on PORTB
-    \\-------------------------
-    \\  1001 // (initial state of PORTB)
-    \\| 0100 // (bitmask)
-    \\= 1101
-    \\
-    \\  1001 // (reset state)
-    \\| 0100 // (bitmask)
-    \\= 1101
-    \\
-    \\Clear pins with AND and NOT on PORTB
-    \\------------------------------------
-    \\  1110 // (initial state of PORTB)
-    \\& 1011 // (bitmask)
-    \\= 1010
-    \\
-    \\  0111 // (reset state)
-    \\& 1110 // (bitmask)
-    \\= 0110
-    },
-    .{
-        .main_file = "114_packed.zig",
-        .output = "",
-    },
-    .{
-        .main_file = "115_packed2.zig",
-        .output = "",
-    },
-    .{
-        .main_file = "999_the_end.zig",
-        .output =
-        \\
-        \\This is the end for now!
-        \\We hope you had fun and were able to learn a lot, so visit us again when the next exercises are available.
-        , // pay attention to the comma
-    },
-};