From 174b16199e6d893b3baefac7f8ecc243d5f032a8 Mon Sep 17 00:00:00 2001
From: kayomn <kayomn@kayomn.net>
Date: Wed, 19 Oct 2022 11:21:54 +0100
Subject: [PATCH] Split archive FS logic into its own file

---
 src/engine/sys.zig         | 38 +++++++-------------------------------
 src/engine/sys/Archive.zig | 29 +++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 31 deletions(-)
 create mode 100644 src/engine/sys/Archive.zig

diff --git a/src/engine/sys.zig b/src/engine/sys.zig
index 427ac7c..63a01c5 100644
--- a/src/engine/sys.zig
+++ b/src/engine/sys.zig
@@ -1,3 +1,5 @@
+const Archive = @import("./sys/Archive.zig");
+
 const ext = @cImport({
     @cInclude("SDL2/SDL.h");
 });
@@ -148,7 +150,7 @@ pub const AppContext = opaque {
                 .user_path_prefix = user_path_prefix,
 
                 .data_file_system = .{.archive = .{
-                    .index_cache = try FileSystem.ArchiveIndexCache.init(allocator),
+                    .index_cache = try Archive.IndexCache.init(allocator),
                     .file_access = data_archive_file_access,
                 }},
 
@@ -269,33 +271,7 @@ pub const AppContext = opaque {
 ///
 pub const FileSystem = union(enum) {
     native: []const u8,
-
-    archive: struct {
-        file_access: ona.io.FileAccess,
-        index_cache: ArchiveIndexCache,
-
-        entry_table: [max_open_entries]ArchiveEntry =
-            std.mem.zeroes([max_open_entries]ArchiveEntry),
-
-        const max_open_entries = 16;
-    },
-
-    ///
-    ///
-    ///
-    const ArchiveEntry = struct {
-        owner: ?*ona.io.FileAccess,
-        cursor: u64,
-        header: oar.Entry,
-    };
-
-    ///
-    ///
-    ///
-    const ArchiveIndexCache = ona.table.Hashed(oar.Path, u64, .{
-        .equals = oar.Path.equals,
-        .hash = oar.Path.hash,
-    });
+    archive: Archive,
 
     ///
     /// Platform-agnostic mechanism for referencing files and directories on a [FileSystem].
@@ -379,9 +355,9 @@ pub const FileSystem = union(enum) {
 
                     for (archive.entry_table) |*entry| if (entry.owner == null) {
                         const Implementation = struct {
-                            fn archiveEntryCast(context: *anyopaque) *ArchiveEntry {
-                                return @ptrCast(*ArchiveEntry, @alignCast(
-                                    @alignOf(ArchiveEntry), context));
+                            fn archiveEntryCast(context: *anyopaque) *Archive.Entry {
+                                return @ptrCast(*Archive.Entry, @alignCast(
+                                    @alignOf(Archive.Entry), context));
                             }
 
                             fn close(context: *anyopaque) void {
diff --git a/src/engine/sys/Archive.zig b/src/engine/sys/Archive.zig
new file mode 100644
index 0000000..500ff4a
--- /dev/null
+++ b/src/engine/sys/Archive.zig
@@ -0,0 +1,29 @@
+const oar = @import("oar");
+const ona = @import("ona");
+const std = @import("std");
+
+file_access: ona.io.FileAccess,
+index_cache: IndexCache,
+entry_table: [max_open_entries]Entry = std.mem.zeroes([max_open_entries]Entry),
+
+///
+/// Hard limit on the maximum number of entries open at once.
+///
+const max_open_entries = 16;
+
+///
+/// Stateful extension of an [oar.Entry].
+///
+pub const Entry = struct {
+    owner: ?*ona.io.FileAccess,
+    cursor: u64,
+    header: oar.Entry,
+};
+
+///
+/// Table cache for associating [oar.Path] values with offsets to entries in a given file.
+///
+pub const IndexCache = ona.table.Hashed(oar.Path, u64, .{
+    .equals = oar.Path.equals,
+    .hash = oar.Path.hash,
+});