Clear to end of each line in left prompt

src/fish_tests.cpp

@@ -5740,19 +5740,19 @@ void test_layout_cache() {
     for (size_t i = 0; i < layout_cache_t::prompt_cache_max_size; i++) {
         wcstring input = std::to_wstring(i);
         do_test(!seqs.find_prompt_layout(input));
-        seqs.add_prompt_layout({input, huge, input, {i, 0, 0}});
+        seqs.add_prompt_layout({input, huge, input, {{}, i, 0}});
-        do_test(seqs.find_prompt_layout(input)->layout.line_count == i);
+        do_test(seqs.find_prompt_layout(input)->layout.max_line_width == i);
     }
 
     size_t expected_evictee = 3;
     for (size_t i = 0; i < layout_cache_t::prompt_cache_max_size; i++) {
         if (i != expected_evictee)
-            do_test(seqs.find_prompt_layout(std::to_wstring(i))->layout.line_count == i);
+            do_test(seqs.find_prompt_layout(std::to_wstring(i))->layout.max_line_width == i);
     }
 
-    seqs.add_prompt_layout({L"whatever", huge, L"whatever", {100, 0, 0}});
+    seqs.add_prompt_layout({L"whatever", huge, L"whatever", {{}, 100, 0}});
     do_test(!seqs.find_prompt_layout(std::to_wstring(expected_evictee)));
-    do_test(seqs.find_prompt_layout(L"whatever", huge)->layout.line_count == 100);
+    do_test(seqs.find_prompt_layout(L"whatever", huge)->layout.max_line_width == 100);
 }
 
 void test_prompt_truncation() {
@@ -5762,7 +5762,16 @@ void test_prompt_truncation() {
 
     /// Helper to return 'layout' formatted as a string for easy comparison.
     auto format_layout = [&] {
-        return format_string(L"%lu,%lu,%lu", (unsigned long)layout.line_count,
+        wcstring line_breaks = L"";
+        bool first = true;
+        for (const size_t line_break : layout.line_breaks) {
+            if (!first) {
+                line_breaks.push_back(L',');
+            }
+            line_breaks.append(format_string(L"%lu", (unsigned long)line_break));
+            first = false;
+        }
+        return format_string(L"[%ls],%lu,%lu", line_breaks.c_str(),
                              (unsigned long)layout.max_line_width,
                              (unsigned long)layout.last_line_width);
     };
@@ -5774,12 +5783,22 @@ void test_prompt_truncation() {
 
     // No truncation.
     layout = cache.calc_prompt_layout(L"abcd", &trunc);
-    do_test(format_layout() == L"1,4,4");
+    do_test(format_layout() == L"[],4,4");
     do_test(trunc == L"abcd");
 
+    // Line break calculation.
+    layout = cache.calc_prompt_layout(join({
+                                          L"0123456789ABCDEF",  //
+                                          L"012345",            //
+                                          L"0123456789abcdef",  //
+                                          L"xyz"                //
+                                      }),
+                                      &trunc, 80);
+    do_test(format_layout() == L"[16,23,40],16,3");
+
     // Basic truncation.
     layout = cache.calc_prompt_layout(L"0123456789ABCDEF", &trunc, 8);
-    do_test(format_layout() == L"1,8,8");
+    do_test(format_layout() == L"[],8,8");
     do_test(trunc == ellipsis + L"9ABCDEF");
 
     // Multiline truncation.
@@ -5790,24 +5809,24 @@ void test_prompt_truncation() {
                                           L"xyz"                //
                                       }),
                                       &trunc, 8);
-    do_test(format_layout() == L"4,8,3");
+    do_test(format_layout() == L"[8,15,24],8,3");
     do_test(trunc == join({ellipsis + L"9ABCDEF", L"012345", ellipsis + L"9abcdef", L"xyz"}));
 
     // Escape sequences are not truncated.
     layout =
         cache.calc_prompt_layout(L"\x1B]50;CurrentDir=test/foo\x07NOT_PART_OF_SEQUENCE", &trunc, 4);
-    do_test(format_layout() == L"1,4,4");
+    do_test(format_layout() == L"[],4,4");
     do_test(trunc == ellipsis + L"\x1B]50;CurrentDir=test/foo\x07NCE");
 
     // Newlines in escape sequences are skipped.
     layout = cache.calc_prompt_layout(L"\x1B]50;CurrentDir=\ntest/foo\x07NOT_PART_OF_SEQUENCE",
                                       &trunc, 4);
-    do_test(format_layout() == L"1,4,4");
+    do_test(format_layout() == L"[],4,4");
     do_test(trunc == ellipsis + L"\x1B]50;CurrentDir=\ntest/foo\x07NCE");
 
     // We will truncate down to one character if we have to.
     layout = cache.calc_prompt_layout(L"Yay", &trunc, 1);
-    do_test(format_layout() == L"1,1,1");
+    do_test(format_layout() == L"[],1,1");
     do_test(trunc == ellipsis);
 }
 

src/screen.cpp

@@ -368,7 +368,7 @@ prompt_layout_t layout_cache_t::calc_prompt_layout(const wcstring &prompt_str,
     size_t prompt_len = prompt_str.size();
     const wchar_t *prompt = prompt_str.c_str();
 
-    prompt_layout_t layout = {1, 0, 0};
+    prompt_layout_t layout = {{}, 0, 0};
     wcstring trunc_prompt;
 
     size_t run_start = 0;
@@ -389,7 +389,9 @@ prompt_layout_t layout_cache_t::calc_prompt_layout(const wcstring &prompt_str,
 
         wchar_t endc = prompt[run_end];
         if (endc) {
-            layout.line_count += (endc == L'\n' || endc == L'\f');
+            if (endc == L'\n' || endc == L'\f') {
+                layout.line_breaks.push_back(trunc_prompt.size());
+            }
             trunc_prompt.push_back(endc);
             run_start = run_end + 1;
         } else {
@@ -409,7 +411,7 @@ static size_t calc_prompt_lines(const wcstring &prompt) {
     // calc_prompt_width_and_lines.
     size_t result = 1;
     if (prompt.find_first_of(L"\n\f") != wcstring::npos) {
-        result = layout_cache_t::shared.calc_prompt_layout(prompt).line_count;
+        result = layout_cache_t::shared.calc_prompt_layout(prompt).line_breaks.size() + 1;
     }
     return result;
 }
@@ -696,7 +698,8 @@ static void s_update(screen_t *scr, const wcstring &left_prompt, const wcstring
     const scoped_buffer_t buffering(*scr);
 
     // Determine size of left and right prompt. Note these have already been truncated.
-    const size_t left_prompt_width = cached_layouts.calc_prompt_layout(left_prompt).last_line_width;
+    const prompt_layout_t left_prompt_layout = cached_layouts.calc_prompt_layout(left_prompt);
+    const size_t left_prompt_width = left_prompt_layout.last_line_width;
     const size_t right_prompt_width =
         cached_layouts.calc_prompt_layout(right_prompt).last_line_width;
 
@@ -734,7 +737,15 @@ static void s_update(screen_t *scr, const wcstring &left_prompt, const wcstring
     // Output the left prompt if it has changed.
     if (left_prompt != scr->actual_left_prompt) {
         s_move(scr, 0, 0);
-        s_write_str(scr, left_prompt.c_str());
+        size_t start = 0;
+        for (const size_t line_break : left_prompt_layout.line_breaks) {
+            s_write_str(scr, left_prompt.substr(start, line_break - start).c_str());
+            if (clr_eol) {
+                s_write_mbs(scr, clr_eol);
+            }
+            start = line_break;
+        }
+        s_write_str(scr, left_prompt.c_str() + start);
         scr->actual_left_prompt = left_prompt;
         scr->actual.cursor.x = static_cast<int>(left_prompt_width);
     }

src/screen.h

@@ -213,9 +213,9 @@ void screen_force_clear_to_end();
 
 // Information about the layout of a prompt.
 struct prompt_layout_t {
-    size_t line_count;       // how many lines the prompt consumes
+    std::vector<size_t> line_breaks;  // line breaks when rendering the prompt
-    size_t max_line_width;   // width of the longest line
+    size_t max_line_width;            // width of the longest line
-    size_t last_line_width;  // width of the last line
+    size_t last_line_width;           // width of the last line
 };
 
 // Maintain a mapping of escape sequences to their widths for fast lookup.