terminal/tmux: parse session-changed notification

src/terminal/tmux.zig

@@ -5,6 +5,7 @@
 
 const std = @import("std");
 const assert = std.debug.assert;
+const oni = @import("oniguruma");
 
 const log = std.log.scoped(.terminal_tmux);
 
@@ -15,7 +16,7 @@ pub const Client = struct {
     /// Current state of the client.
     state: State = .idle,
 
-    /// The buffer used to store in-progress commands, output, etc.
+    /// The buffer used to store in-progress notifications, output, etc.
     buffer: std.ArrayList(u8),
 
     /// The maximum size in bytes of the buffer. This is used to limit
@@ -25,16 +26,18 @@ pub const Client = struct {
     max_bytes: usize = 1024 * 1024,
 
     const State = enum {
-        /// Outside of any active command. This should drop any output
+        /// Outside of any active notifications. This should drop any output
-        /// unless it is '%' on the first byte of a line.
+        /// unless it is '%' on the first byte of a line. The buffer will be
+        /// cleared when it sees '%', this is so that the previous notification
+        /// data is valid until we receive/process new data.
         idle,
 
         /// We experienced unexpected input and are in a broken state
         /// so we cannot continue processing.
         broken,
 
-        /// Inside an active command (started with '%').
+        /// Inside an active notification (started with '%').
-        command,
+        notification,
 
         /// Inside a begin/end block.
         block,
@@ -55,24 +58,27 @@ pub const Client = struct {
             // Drop because we're in a broken state.
             .broken => return null,
 
-            // Waiting for a command so if the byte is not '%' then
+            // Waiting for a notification so if the byte is not '%' then
-            // we're in a broken state. Return an exit command.
+            // we're in a broken state. Control mode output should always
+            // be wrapped in '%begin/%end' orelse we expect a notification.
+            // Return an exit notification.
             .idle => if (byte != '%') {
                 self.broken();
                 return .{ .exit = {} };
             } else {
-                self.state = .command;
+                self.buffer.clearRetainingCapacity();
+                self.state = .notification;
             },
 
-            // If we're in a command and its not a newline then
+            // If we're in a notification and its not a newline then
             // we accumulate. If it is a newline then we have a
-            // complete command we need to parse.
+            // complete notification we need to parse.
-            .command => if (byte == '\n') {
+            .notification => if (byte == '\n') {
-                // We have a complete command, parse it.
+                // We have a complete notification, parse it.
                 return try self.parseNotification();
             },
 
-            // If we're ina block then we accumulate until we see a newline
+            // If we're in a block then we accumulate until we see a newline
             // and then we check to see if that line ended the block.
             .block => if (byte == '\n') {
                 const idx = if (std.mem.lastIndexOfScalar(
@@ -81,6 +87,7 @@ pub const Client = struct {
                     '\n',
                 )) |v| v + 1 else 0;
                 const line = self.buffer.items[idx..];
+
                 if (std.mem.startsWith(u8, line, "%end") or
                     std.mem.startsWith(u8, line, "%error"))
                 {
@@ -95,6 +102,8 @@ pub const Client = struct {
                     self.buffer.clearRetainingCapacity();
                     return null;
                 }
+
+                // Didn't end the block, continue accumulating.
             },
         }
 
@@ -104,11 +113,12 @@ pub const Client = struct {
     }
 
     fn parseNotification(self: *Client) !?Notification {
-        assert(self.state == .command);
+        assert(self.state == .notification);
 
-        var it = std.mem.tokenizeScalar(u8, self.buffer.items, ' ');
+        const line = self.buffer.items;
+        var it = std.mem.tokenizeScalar(u8, line, ' ');
 
-        // The command MUST exist because we guard entering the command
+        // The notification MUST exist because we guard entering the notification
         // state on seeing at least a '%'.
         const cmd = it.next().?;
         if (std.mem.eql(u8, cmd, "%begin")) {
@@ -123,12 +133,40 @@ pub const Client = struct {
             self.state = .block;
             self.buffer.clearRetainingCapacity();
             return null;
+        } else if (std.mem.eql(u8, cmd, "%session-changed")) cmd: {
+            var re = try oni.Regex.init(
+                "^%session-changed \\$([0-9]+) (.+)$",
+                .{ .capture_group = true },
+                oni.Encoding.utf8,
+                oni.Syntax.default,
+                null,
+            );
+            defer re.deinit();
+
+            var region = re.search(line, .{}) catch |err| {
+                log.warn("failed to match notification cmd={s} err={}", .{ cmd, err });
+                break :cmd;
+            };
+            defer region.deinit();
+            const starts = region.starts();
+            const ends = region.ends();
+
+            const id = std.fmt.parseInt(
+                usize,
+                line[@intCast(starts[1])..@intCast(ends[1])],
+                10,
+            ) catch unreachable;
+            const name = line[@intCast(starts[2])..@intCast(ends[2])];
+
+            // Important: do not clear buffer here since name points to it
+            self.state = .idle;
+            return .{ .session_changed = .{ .id = id, .name = name } };
         } else {
-            // Unknown command, log it and return to idle state.
+            // Unknown notification, log it and return to idle state.
-            log.warn("unknown tmux control mode command={s}", .{cmd});
+            log.warn("unknown tmux control mode notification={s}", .{cmd});
         }
 
-        // Successful exit, revert to idle state.
+        // Unknown command. Clear the buffer and return to idle state.
         self.buffer.clearRetainingCapacity();
         self.state = .idle;
 
@@ -147,6 +185,11 @@ pub const Client = struct {
 pub const Notification = union(enum) {
     enter: void,
     exit: void,
+
+    session_changed: struct {
+        id: usize,
+        name: []const u8,
+    },
 };
 
 test "tmux begin/end empty" {
@@ -168,3 +211,16 @@ test "tmux begin/error empty" {
     for ("%begin 1578922740 269 1\n") |byte| try testing.expect(try c.put(byte) == null);
     for ("%error 1578922740 269 1\n") |byte| try testing.expect(try c.put(byte) == null);
 }
+
+test "tmux session-changed" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+
+    var c: Client = .{ .buffer = std.ArrayList(u8).init(alloc) };
+    defer c.deinit();
+    for ("%session-changed $42 foo") |byte| try testing.expect(try c.put(byte) == null);
+    const n = (try c.put('\n')).?;
+    try testing.expect(n == .session_changed);
+    try testing.expectEqual(42, n.session_changed.id);
+    try testing.expectEqualStrings("foo", n.session_changed.name);
+}