terminal: track semantic prompt metadata per row

src/terminal/Screen.zig

@@ -136,7 +136,32 @@ pub const RowHeader = struct {
 
         /// True if any cell in this row has a grapheme associated with it.
         grapheme: bool = false,
+
+        /// True if this row is an active prompt (awaiting input). This is
+        /// set to false when the semantic prompt events (OSC 133) are received.
+        /// There are scenarios where the shell may never send this event, so
+        /// in order to reliably test prompt status, you need to iterate
+        /// backwards from the cursor to check the current line status going
+        /// back.
+        semantic_prompt: SemanticPrompt = .unknown,
     } = .{},
+
+    /// Semantic prompt type.
+    pub const SemanticPrompt = enum(u3) {
+        /// Unknown, the running application didn't tell us for this line.
+        unknown = 0,
+
+        /// This is a prompt line, meaning it only contains the shell prompt.
+        /// For poorly behaving shells, this may also be the input.
+        prompt = 1,
+
+        /// This line contains the input area. We don't currently track
+        /// where this actually is in the line, so we just assume it is somewhere.
+        input = 2,
+
+        /// This line is the start of command output.
+        command = 3,
+    };
 };
 
 /// Cell is a single cell within the screen.
@@ -276,6 +301,16 @@ pub const Row = struct {
         return self.storage[0].header.flags.dirty;
     }
 
+    /// Set the semantic prompt state for this row.
+    pub fn setSemanticPrompt(self: Row, p: RowHeader.SemanticPrompt) void {
+        self.storage[0].header.flags.semantic_prompt = p;
+    }
+
+    /// Retrieve the semantic prompt state for this row.
+    pub fn getSemanticPrompt(self: Row) RowHeader.SemanticPrompt {
+        return self.storage[0].header.flags.semantic_prompt;
+    }
+
     /// Retrieve the header for this row.
     pub fn header(self: Row) RowHeader {
         return self.storage[0].header;

src/terminal/Terminal.zig

@@ -31,6 +31,17 @@ pub const ScreenType = enum {
     alternate,
 };
 
+/// The semantic prompt type. This is used when tracking a line type and
+/// requires integration with the shell. By default, we mark a line as "none"
+/// meaning we don't know what type it is.
+///
+/// See: https://gitlab.freedesktop.org/Per_Bothner/specifications/blob/master/proposals/semantic-prompts.md
+pub const SemanticPrompt = enum {
+    prompt,
+    input,
+    command,
+};
+
 /// Screen is the current screen state. The "active_screen" field says what
 /// the current screen is. The backup screen is the opposite of the active
 /// screen.
@@ -1386,6 +1397,50 @@ pub fn setScrollingRegion(self: *Terminal, top: usize, bottom: usize) void {
     self.setCursorPos(1, 1);
 }
 
+/// Mark the current semantic prompt information. Current escape sequences
+/// (OSC 133) only allow setting this for wherever the current active cursor
+/// is located.
+pub fn markSemanticPrompt(self: *Terminal, p: SemanticPrompt) void {
+    const row = self.screen.getRow(.{ .active = self.screen.cursor.y });
+    row.setSemanticPrompt(switch (p) {
+        .prompt => .prompt,
+        .input => .input,
+        .command => .command,
+    });
+}
+
+/// Returns true if the cursor is currently at a prompt. Another way to look
+/// at this is it returns false if the shell is currently outputing something.
+/// This requires shell integration (semantic prompt integration).
+///
+/// If the shell integration doesn't exist, this will always return false.
+pub fn cursorIsAtPrompt(self: *Terminal) bool {
+    // If we're on the secondary screen, we're never at a prompt.
+    if (self.active_screen == .alternate) return false;
+
+    var y: usize = 0;
+    while (y <= self.screen.cursor.y) : (y += 1) {
+        // We want to go bottom up
+        const bottom_y = self.screen.cursor.y - y;
+        const row = self.screen.getRow(.{ .active = bottom_y });
+        switch (row.getSemanticPrompt()) {
+            // If we're at a prompt or input area, then we are at a prompt.
+            .prompt,
+            .input,
+            => return true,
+
+            // If we have command output, then we're most certainly not
+            // at a prompt.
+            .command => return false,
+
+            // If we don't know, we keep searching.
+            .unknown => {},
+        }
+    }
+
+    return false;
+}
+
 /// Full reset
 pub fn fullReset(self: *Terminal) void {
     self.primaryScreen(.{ .clear_on_exit = true, .cursor_save = true });
@@ -2117,3 +2172,49 @@ test "Terminal: insertBlanks more than size" {
         try testing.expectEqualStrings("", str);
     }
 }
+
+test "Terminal: cursorIsAtPrompt" {
+    const alloc = testing.allocator;
+    var t = try init(alloc, 3, 2);
+    defer t.deinit(alloc);
+
+    try testing.expect(!t.cursorIsAtPrompt());
+    t.markSemanticPrompt(.prompt);
+    try testing.expect(t.cursorIsAtPrompt());
+
+    // Input is also a prompt
+    t.markSemanticPrompt(.input);
+    try testing.expect(t.cursorIsAtPrompt());
+
+    // Newline -- we expect we're still at a prompt if we received
+    // prompt stuff before.
+    try t.linefeed();
+    try testing.expect(t.cursorIsAtPrompt());
+
+    // But once we say we're starting output, we're not a prompt
+    t.markSemanticPrompt(.command);
+    try testing.expect(!t.cursorIsAtPrompt());
+    try t.linefeed();
+    try testing.expect(!t.cursorIsAtPrompt());
+
+    // Until we know we're at a prompt again
+    try t.linefeed();
+    t.markSemanticPrompt(.prompt);
+    try testing.expect(t.cursorIsAtPrompt());
+}
+
+test "Terminal: cursorIsAtPrompt alternate screen" {
+    const alloc = testing.allocator;
+    var t = try init(alloc, 3, 2);
+    defer t.deinit(alloc);
+
+    try testing.expect(!t.cursorIsAtPrompt());
+    t.markSemanticPrompt(.prompt);
+    try testing.expect(t.cursorIsAtPrompt());
+
+    // Secondary screen is never a prompt
+    t.alternateScreen(.{});
+    try testing.expect(!t.cursorIsAtPrompt());
+    t.markSemanticPrompt(.prompt);
+    try testing.expect(!t.cursorIsAtPrompt());
+}

src/terminal/osc.zig

@@ -276,6 +276,7 @@ pub const Parser = struct {
                     self.command = .{ .end_of_command = .{} };
                     self.complete = true;
                 },
+
                 else => self.state = .invalid,
             },
 

src/terminal/stream.zig

@@ -471,6 +471,24 @@ pub fn Stream(comptime Handler: type) type {
                     } else log.warn("unimplemented OSC callback: {}", .{cmd});
                 },
 
+                .prompt_start => {
+                    if (@hasDecl(T, "promptStart")) {
+                        try self.handler.promptStart();
+                    } else log.warn("unimplemented OSC callback: {}", .{cmd});
+                },
+
+                .prompt_end => {
+                    if (@hasDecl(T, "promptEnd")) {
+                        try self.handler.promptEnd();
+                    } else log.warn("unimplemented OSC callback: {}", .{cmd});
+                },
+
+                .end_of_command => |end| {
+                    if (@hasDecl(T, "endOfCommand")) {
+                        try self.handler.endOfCommand(end.exit_code);
+                    } else log.warn("unimplemented OSC callback: {}", .{cmd});
+                },
+
                 else => if (@hasDecl(T, "oscUnimplemented"))
                     try self.handler.oscUnimplemented(cmd)
                 else