Resetting. Again.

Getting the basics re-added

src/decomp.zig

@@ -1,25 +1,34 @@
 const std = @import("std");
+const build = @import("build_options");
 
-const Decompressor = @This();
+const c = @import("c_decomp.zig");
+const zig = @import("zig_decomp.zig");
+
+pub fn getFn(e: Enum) !Fn {
+    return switch (e) {
+        .gzip => if (build.use_zig_decomp) zig.gzip else c.gzip,
+        .lzma => if (build.use_zig_decomp) zig.lzma else c.lzma,
+        .lzo => if (build.use_zig_decomp or !build.allow_lzo) error.LzoUnsupported else c.lzo,
+        .xz => if (build.use_zig_decomp) zig.xz else c.xz,
+        .lz4 => if (build.use_zig_decomp) error.Lz4Unsupported else c.lz4,
+        .zstd => if (build.use_zig_decomp) zig.zstd else c.zstd,
+    };
+}
+
+// Types
+
+pub const Fn = *fn (std.mem.Allocator, in: []u8, out: []u8) Error!usize;
+
+pub const Enum = enum(u16) {
+    gzip = 1,
+    lzma,
+    lzo,
+    xz,
+    lz4,
+    zstd,
+};
 
 pub const Error = error{
     OutOfMemory,
-    BadInput,
-    OutputTooSmall,
-    ReadFailed,
-    WriteFailed,
-    EndOfStream,
+    DecompressionFailed,
 };
-
-vtable: *const struct {
-    decompress: *const fn (*Decompressor, []u8, []u8) Error!usize = DefaultDecompress,
-    stateless: *const fn (std.mem.Allocator, []u8, []u8) Error!usize,
-},
-
-pub fn decompress(self: *Decompressor, in: []u8, out: []u8) Error!usize {
-    return self.vtable.decompress(self, in, out);
-}
-
-fn DefaultDecompress(self: *Decompressor, in: []u8, out: []u8) Error!usize {
-    return self.vtable.stateless(std.heap.smp_allocator, in, out);
-}