ziglang simple implementation for print file tree

tree.zig

// zig version: 0.15.1+

const std = @import("std");

const Entry = struct {
    name: []const u8,
    kind: std.fs.Dir.Entry.Kind,
};

pub fn main() !void {
    const allocator = std.heap.page_allocator;
    const args = try std.process.argsAlloc(allocator);
    defer std.process.argsFree(allocator, args);
    const root = if (args.len > 1) args[1] else ".";
    const out = std.fs.File.stdout();
    var writer = out.writer(&.{}).interface;
    try writer.print("{s}\n", .{root});
    try printDirectory(allocator, root, "", &writer);
}

const indent_unicode = "│   ";
const indent_space = "    ";
const suffix_last = "└──";
const suffix_mid = "├──";

fn printDirectory(allocator: std.mem.Allocator, path: []const u8, indent: []const u8, writer: *std.Io.Writer) !void {
    var dir = try std.fs.cwd().openDir(path, .{ .iterate = true });
    defer dir.close();

    var entries = try std.ArrayList(Entry).initCapacity(allocator, 64);
    defer {
        for (entries.items) |entry| {
            allocator.free(entry.name);
        }
        entries.deinit(allocator);
    }

    var it = dir.iterate();
    while (try it.next()) |entry| {
        const name_copy = try allocator.dupe(u8, entry.name);
        try entries.append(allocator, Entry{
            .name = name_copy,
            .kind = entry.kind,
        });
    }

    const count = entries.items.len;
    for (entries.items, 0..) |entry, index| {
        const is_last = index + 1 == count;
        const middle = if (is_last) indent_space else indent_unicode;
        const suffix = if (is_last) suffix_last else suffix_mid;

        try writer.print("{s}{s} {s}\n", .{ indent, suffix, entry.name });

        if (entry.kind == .directory) {
            const full_len = path.len + 1 + entry.name.len;
            var path_buf = try allocator.alloc(u8, full_len);
            defer allocator.free(path_buf);

            std.mem.copyForwards(u8, path_buf[0..path.len], path);
            path_buf[path.len] = '/';
            std.mem.copyForwards(u8, path_buf[path.len + 1 ..], entry.name);
            const sub_path = path_buf[0..full_len];

            var buf: [512]u8 = undefined;
            const sub_indent = try std.fmt.bufPrint(&buf, "{s}{s}", .{ indent, middle });

            try printDirectory(allocator, sub_path, sub_indent, writer);
        }
    }
}

zig build-exe tree.zig

./tree

.
├── .idea
│   ├── .gitignore
│   ├── libraries
│   │   └── Zig_SDK.xml
│   ├── modules.xml
│   ├── tree.iml
│   ├── workspace.xml
│   ├── ZigBrains.iml
│   └── zigbrains.xml
├── .zig-cache
│   ├── h
│   ├── o
│   │   └── f9e331f7aac48a32e9218fa9422851f7
│   └── z
│       └── 2e6d917aa7ba84914dbf9210541c5c74
├── build.zig
├── build.zig.zon
├── src
│   ├── tree.exe
│   ├── tree.exe.obj
│   ├── tree.pdb
│   └── tree.zig
└── ZigBrains.iml