Add a tagged union for all backend messages.

Move read_message to proto.zig and make it return the tagged union
rather than expecting a message type.

1 files changed, 3 insertions, 13 deletions

diff --git a/src/main.zig b/src/main.zig
index 818b3b7..9ce8de9 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -3,8 +3,9 @@ const testing = std.testing;
 
 pub const ProtocolError = error{
     InvalidProtocolVersion,
-    InvalidKeyValuePair,
+    InvalidMessageType,
     InvalidMessageLength,
+    InvalidKeyValuePair,
     InvalidAuthType,
     MissingField,
     WrongMessageType,
@@ -41,17 +42,6 @@ pub fn enum_from_int(comptime e: type, i: anytype) ?e {
     }
 }
 
-// Tag should already have been read in order to determine msg_type!
-pub fn read_message(comptime msg_type: type, allocator: std.mem.Allocator, stream_reader: anytype) !msg_type {
-    if (!@hasDecl(msg_type, "Tag")) @compileError("msg_type must have a Tag declaration!");
-    if (!@hasDecl(msg_type, "read")) @compileError("msg_type must have a read() function!");
-    const len = try stream_reader.readIntBig(u32);
-    const buf = try allocator.alloc(u8, @as(u32, @intCast(len - 4)));
-    defer allocator.free(buf);
-    try stream_reader.readNoEof(buf);
-    return try msg_type.read(allocator, buf);
-}
-
 pub fn diagnosticReader(comptime n: usize, base_reader: anytype) DiagnosticReader(n, @TypeOf(base_reader)) {
     return .{ .child_reader = base_reader };
 }
@@ -81,7 +71,7 @@ pub fn DiagnosticReader(comptime n: usize, comptime ReaderType: anytype) type {
         }
 
         // Caller frees
-        pub fn get(self: @This(), allocator: std.mem.Allocator) ![]const u8 {
+        pub fn get(self: @This(), allocator: std.mem.Allocator) ![]u8 {
             var buf = try allocator.alloc(u8, n);
             errdefer allocator.free(buf);
             @memcpy(buf[0..(n - self.pos)], self.ring[self.pos..n]);