Move protocol code generators to liberty

This part of the project is now more or less stable.

xC.lxdr

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+// Backwards-compatible protocol version.
+const VERSION = 1;
+
+// From the frontend to the relay.
+struct CommandMessage {
+	// The command sequence number will be repeated in responses
+	// in the respective fields.
+	u32 command_seq;
+	union CommandData switch (enum Command {
+		HELLO,
+		ACTIVE,
+		BUFFER_ACTIVATE,
+		BUFFER_INPUT,
+		BUFFER_TOGGLE_UNIMPORTANT,
+		PING_RESPONSE,
+		PING,
+		BUFFER_COMPLETE,
+		BUFFER_LOG,
+	} command) {
+	// If the version check succeeds, the client will receive
+	// an initial stream of SERVER_UPDATE, BUFFER_UPDATE, BUFFER_STATS,
+	// BUFFER_LINE, and finally a BUFFER_ACTIVATE message.
+	case HELLO:
+		u32 version;
+	case ACTIVE:
+		void;
+	case BUFFER_ACTIVATE:
+		string buffer_name;
+	case BUFFER_INPUT:
+		string buffer_name;
+		string text;
+	// XXX: Perhaps this should rather be handled through a /buffer command.
+	case BUFFER_TOGGLE_UNIMPORTANT:
+		string buffer_name;
+	case PING_RESPONSE:
+		u32 event_seq;
+
+	// Only these commands may produce Event.RESPONSE, as below,
+	// but any command may produce an error.
+	case PING:
+		void;
+	case BUFFER_COMPLETE:
+		string buffer_name;
+		string text;
+		u32 position;
+	case BUFFER_LOG:
+		string buffer_name;
+	} data;
+};
+
+// From the relay to the frontend.
+struct EventMessage {
+	u32 event_seq;
+	union EventData switch (enum Event {
+		PING,
+		BUFFER_LINE,
+		BUFFER_UPDATE,
+		BUFFER_STATS,
+		BUFFER_RENAME,
+		BUFFER_REMOVE,
+		BUFFER_ACTIVATE,
+		BUFFER_CLEAR,
+		SERVER_UPDATE,
+		SERVER_RENAME,
+		SERVER_REMOVE,
+		ERROR,
+		RESPONSE,
+	} event) {
+	case PING:
+		void;
+
+	case BUFFER_LINE:
+		string buffer_name;
+		// Whether the line should also be displayed in the active buffer.
+		bool leak_to_active;
+		bool is_unimportant;
+		bool is_highlight;
+		enum Rendition {
+			BARE,
+			INDENT,
+			STATUS,
+			ERROR,
+			JOIN,
+			PART,
+			ACTION,
+		} rendition;
+		// Unix timestamp in milliseconds.
+		u64 when;
+		// Broken-up text, with in-band formatting.
+		union ItemData switch (enum Item {
+			TEXT,
+			RESET,
+			FG_COLOR,
+			BG_COLOR,
+			FLIP_BOLD,
+			FLIP_ITALIC,
+			FLIP_UNDERLINE,
+			FLIP_INVERSE,
+			FLIP_CROSSED_OUT,
+			FLIP_MONOSPACE,
+		} kind) {
+		case TEXT:
+			string text;
+		case RESET:
+			void;
+		case FG_COLOR:
+			i16 color;
+		case BG_COLOR:
+			i16 color;
+		case FLIP_BOLD:
+		case FLIP_ITALIC:
+		case FLIP_UNDERLINE:
+		case FLIP_INVERSE:
+		case FLIP_CROSSED_OUT:
+		case FLIP_MONOSPACE:
+			void;
+		} items<>;
+	case BUFFER_UPDATE:
+		string buffer_name;
+		bool hide_unimportant;
+		union BufferContext switch (enum BufferKind {
+			GLOBAL,
+			SERVER,
+			CHANNEL,
+			PRIVATE_MESSAGE,
+		} kind) {
+		case GLOBAL:
+			void;
+		case SERVER:
+			string server_name;
+		case CHANNEL:
+			string server_name;
+			ItemData topic<>;
+			// This includes parameters, separated by spaces.
+			string modes;
+		case PRIVATE_MESSAGE:
+			string server_name;
+		} context;
+	case BUFFER_STATS:
+		string buffer_name;
+		// These are cumulative, even for lines flushed out from buffers.
+		// Updates to these values aren't broadcasted, thus handle:
+		//  - BUFFER_LINE by bumping/setting them as appropriate,
+		//  - BUFFER_ACTIVATE by clearing them for the previous buffer
+		//    (this way, they can be used to mark unread messages).
+		u32 new_messages;
+		u32 new_unimportant_messages;
+		bool highlighted;
+	case BUFFER_RENAME:
+		string buffer_name;
+		string new;
+	case BUFFER_REMOVE:
+		string buffer_name;
+	case BUFFER_ACTIVATE:
+		string buffer_name;
+	case BUFFER_CLEAR:
+		string buffer_name;
+
+	case SERVER_UPDATE:
+		string server_name;
+		union ServerData switch (enum ServerState {
+			DISCONNECTED,
+			CONNECTING,
+			CONNECTED,
+			REGISTERED,
+			DISCONNECTING,
+		} state) {
+		case DISCONNECTED:
+		case CONNECTING:
+		case CONNECTED:
+			void;
+		case REGISTERED:
+			string user;
+			string user_modes;
+		// Theoretically, we could also send user information in this state,
+		// but we'd have to duplicate both fields.
+		case DISCONNECTING:
+			void;
+		} data;
+	case SERVER_RENAME:
+		// Buffers aren't sent updates for in this circumstance,
+		// as that wouldn't be sufficiently atomic anyway.
+		string server_name;
+		string new;
+	case SERVER_REMOVE:
+		string server_name;
+
+	// Restriction: command_seq strictly follows the sequence received
+	// by the relay, across both of these replies.
+	case ERROR:
+		u32 command_seq;
+		string error;
+	case RESPONSE:
+		u32 command_seq;
+		union ResponseData switch (Command command) {
+		case PING:
+			void;
+		case BUFFER_COMPLETE:
+			u32 start;
+			string completions<>;
+		case BUFFER_LOG:
+			// UTF-8, but not guaranteed.
+			u8 log<>;
+		} data;
+	} data;
+};