From ddc1d65befcc98da57c0a29d314de4f11e3c0760 Mon Sep 17 00:00:00 2001
From: Philippe Pittoli <karchnu@karchnu.fr>
Date: Fri, 3 Feb 2023 04:06:52 +0100
Subject: [PATCH] Crystal bindings: CBOR utils.

---
 zig-impl/crystal/some-crystal-app/src/cbor.cr | 71 +++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 zig-impl/crystal/some-crystal-app/src/cbor.cr

diff --git a/zig-impl/crystal/some-crystal-app/src/cbor.cr b/zig-impl/crystal/some-crystal-app/src/cbor.cr
new file mode 100644
index 0000000..5dec5e9
--- /dev/null
+++ b/zig-impl/crystal/some-crystal-app/src/cbor.cr
@@ -0,0 +1,71 @@
+require "cbor"
+
+# IPC::CBOR is the root class for all exchanged messages (using CBOR).
+# IPC::CBOR inherited classes have a common 'type' class attribute,
+# which enables to find the right IPC::CBOR+ class given a TypedMessage's type.
+
+# All transfered messages are typed messages.
+# TypedMessage = u8 type (= IPC::CBOR+ class type) + CBOR content.
+# 'CBOR content' being a serialized IPC::CBOR+ class.
+
+# Conventionally, IPC::CBOR+ classes have a 'handle' method to process incoming messages.
+class IPC::CBOR
+	include ::CBOR::Serializable
+
+	class_property type = -1
+	property     id   : ::CBOR::Any?
+
+	def type
+		@@type
+	end
+
+	macro message(id, type, &block)
+		class {{id}} < ::IPC::CBOR
+			include ::CBOR::Serializable
+
+			@@type = {{type}}
+
+			{{yield}}
+		end
+	end
+end
+
+class IPC
+	# Schedule messages contained into IPC::CBOR+.
+	def schedule(fd : Int32, message : IPC::CBOR)
+		typed_msg = IPCMessage::TypedMessage.new message.type.to_u8, message.to_cbor
+		schedule fd, typed_msg
+	end
+	def write(fd : Int32, message : IPC::CBOR)
+		typed_msg = IPCMessage::TypedMessage.new message.type.to_u8, message.to_cbor
+		write fd, typed_msg
+	end
+end
+
+# CAUTION: Only use this method on an Array(IPC::CBOR.class)
+class Array(T)
+	def parse_ipc_cbor(message : IPC::Message) : IPC::CBOR?
+		message_type = find &.type.==(message.utype)
+
+		if message_type.nil?
+			raise "invalid message type (#{message.utype})"
+		end
+
+		message_type.from_cbor message.payload
+	end
+end
+
+# CAUTION: only use this method on an Array(IPC::CBOR.class).
+class Array(T)
+	def parse_ipc_cbor(message : IPCMessage::TypedMessage) : IPC::CBOR?
+		message_type = find &.type.==(message.type)
+
+		payload = message.payload
+
+		if message_type.nil?
+			raise "invalid message type (#{message.type})"
+		end
+
+		message_type.from_cbor payload
+	end
+end