wip iterator

src/user.zig

@@ -1,6 +1,7 @@
 const std = @import("std");
 const pad = @import("padding.zig");
 
+const assert = std.debug.assert;
 const Allocator = std.mem.Allocator;
 const ArrayList = std.ArrayList;
 const cast = std.math.cast;
@@ -90,6 +91,40 @@ pub const UserWriter = struct {
     }
 };
 
+pub const UserReader = struct {
+    const shellIndexProto = fn (u10) []const u8;
+
+    shellIndex: shellIndexProto,
+    blob: []const u8,
+
+    pub const PackedUserEntry = struct {
+        packed_user: *PackedUser,
+        blob: []const u8,
+    };
+
+    pub fn init(shellIndex: shellIndexProto, blob: []const u8) UserReader {
+        return UserReader{
+            .shellIndex = shellIndex,
+            .blob = blob,
+        };
+    }
+
+    pub const PackedUserIterator = struct {
+        ur: *const UserReader,
+        index: u32 = 0,
+
+        pub fn next(it: *PackedUserIterator) ?PackedUserEntry {
+            if (it.index == it.ur.blob.len) return null;
+            assert(it.index < it.blob.len);
+
+            const start = it.index;
+            const end = it.index + it.index + @sizeOf(PackedUser);
+            var pu = std.mem.bytesAsValue(it.ur.blob[start..end]);
+            _ = pu;
+        }
+    };
+};
+
 const testing = std.testing;
 
 test "PackedUser is byte-aligned" {