Allow getting the last non-empty command output easily via an action or remote control

Fixes #4973

docs/changelog.rst

@@ -39,6 +39,9 @@ Detailed list of changes
 
 - A new command :command:`edit-in-kitty` to :ref:`edit_file`
 
+- Allow getting the last non-empty command output easily via an action or
+  remote control (:pull:`4973`)
+
 - Fix a bug that caused :opt:`macos_colorspace` to always be ``default`` regardless of its actual value (:iss:`5129`)
 
 - ssh kitten: Fix bash not being executed as a login shell since kitty 0.25.0 (:iss:`5130`)

kitty/lineops.h

@@ -73,6 +73,13 @@ left_shift_line(Line *line, index_type at, index_type num) {
     }
 }
 
+static inline bool
+line_is_empty(const Line *line) {
+    for (index_type i = 0; i < line->xnum; i++) {
+        if (line->cpu_cells[i].ch != BLANK_CHAR) return false;
+    }
+    return true;
+}
 
 typedef Line*(get_line_func)(void *, int);
 void line_clear_text(Line *self, unsigned int at, unsigned int num, char_type ch);

kitty/rc/get_text.py

@@ -30,14 +30,15 @@ class GetText(RemoteCommand):
     options_spec = MATCH_WINDOW_OPTION + '''\n
 --extent
 default=screen
-choices=screen, all, selection, first_cmd_output_on_screen, last_cmd_output, last_visited_cmd_output
+choices=screen, all, selection, first_cmd_output_on_screen, last_cmd_output, last_visited_cmd_output, last_non_empty_output
 What text to get. The default of :code:`screen` means all text currently on the screen.
 :code:`all` means all the screen+scrollback and :code:`selection` means the
 currently selected text. :code:`first_cmd_output_on_screen` means the output of the first
 command that was run in the window on screen. :code:`last_cmd_output` means
 the output of the last command that was run in the window. :code:`last_visited_cmd_output` means
-the first command output below the last scrolled position via scroll_to_prompt. The last three
-requires :ref:`shell_integration` to be enabled.
+the first command output below the last scrolled position via scroll_to_prompt.
+:code:`last_non_empty_output` is the output from the last command run in the window that had
+some non empty output. The last four require :ref:`shell_integration` to be enabled.
 
 
 --ansi
@@ -99,6 +100,12 @@ Get text from the window this command is run in, rather than the active window.
                 as_ansi=bool(payload_get('ansi')),
                 add_wrap_markers=bool(payload_get('wrap_markers')),
             )
+        elif payload_get('extent') == 'last_non_empty_output':
+            ans = window.cmd_output(
+                CommandOutput.last_non_empty,
+                as_ansi=bool(payload_get('ansi')),
+                add_wrap_markers=bool(payload_get('wrap_markers')),
+            )
         elif payload_get('extent') == 'last_visited_cmd_output':
             ans = window.cmd_output(
                 CommandOutput.last_visited,

kitty/screen.c

@@ -2859,6 +2859,30 @@ cmd_output(Screen *self, PyObject *args) {
             if (self->last_visited_prompt.scrolled_by <= self->historybuf->count && self->last_visited_prompt.is_set) {
                 found = find_cmd_output(self, &oo, self->last_visited_prompt.y, self->last_visited_prompt.scrolled_by, 0, false);
             } break;
+        case 3: { // last non-empty output
+            int y = self->cursor->y;
+            Line *line;
+            bool reached_upper_limit = false;
+            while (!found && !reached_upper_limit) {
+                line = checked_range_line(self, y);
+                if (!line || (line->attrs.prompt_kind == OUTPUT_START && !line->attrs.continued)) {
+                    int start = line ? y : y + 1; reached_upper_limit = !line;
+                    int y2 = start; unsigned int num_lines = 0;
+                    bool found_content = false;
+                    while ((line = checked_range_line(self, y2)) && line->attrs.prompt_kind != PROMPT_START) {
+                        if (!found_content) found_content = !line_is_empty(line);
+                        num_lines++; y2++;
+                    }
+                    if (found_content) {
+                        found = true;
+                        oo.reached_upper_limit = reached_upper_limit;
+                        oo.start = start; oo.num_lines = num_lines;
+                        break;
+                    }
+                }
+                y--;
+            }
+        } break;
         default:
             PyErr_Format(PyExc_KeyError, "%u is not a valid type of command", which);
             return NULL;

kitty/window.py

@@ -164,7 +164,7 @@ class DynamicColor(IntEnum):
 
 
 class CommandOutput(IntEnum):
-    last_run, first_on_screen, last_visited = 0, 1, 2
+    last_run, first_on_screen, last_visited, last_non_empty = 0, 1, 2, 3
 
 
 DYNAMIC_COLOR_CODES = {
@@ -1460,6 +1460,14 @@ class Window:
     def show_last_visited_command_output(self) -> None:
         self.show_cmd_output(CommandOutput.last_visited, 'Last visited command output')
 
+    @ac('cp', '''
+        Show the last non-empty output from a shell command in a pager like less
+
+        Requires :ref:`shell_integration` to work
+        ''')
+    def show_last_non_empty_command_output(self) -> None:
+        self.show_cmd_output(CommandOutput.last_non_empty, 'Last non-empty command output')
+
     @ac('cp', 'Paste the specified text into the current window')
     def paste(self, text: str) -> None:
         self.paste_with_actions(text)

kitty_tests/screen.py

@@ -1009,9 +1009,9 @@ class TestScreen(BaseTest):
         self.assertTrue(s.scroll_to_prompt())
         self.ae(str(s.visual_line(0)), '$ 1')
 
-        def lco(as_ansi=False):
+        def lco(as_ansi=False, which=0):
             a = []
-            if s.cmd_output(0, a.append, as_ansi):
+            if s.cmd_output(which, a.append, as_ansi):
                 pht = pagerhist(s, as_ansi=as_ansi, upto_output_start=True)
                 if pht:
                     a.insert(0, pht)
@@ -1098,3 +1098,11 @@ class TestScreen(BaseTest):
         draw_prompt('p1')
         draw_output(30)
         self.ae(tuple(map(int, lco().split())), tuple(range(0, 30)))
+
+        # last non empty command output
+        draw_prompt('a'), draw_output(2, 'a')
+        draw_prompt('b'), mark_output()
+        self.ae(lco(), '')
+        self.ae(lco(which=3), '0a\n1a')
+        s.draw('running'), s.index(),  s.carriage_return()
+        self.ae(lco(which=3), 'running\n')