[Lldb-commits] [lldb] [lldb] Improve editline completion formatting (PR #116456)

[Pavel Labath via lldb-commits]

================
@@ -927,12 +927,87 @@ unsigned char Editline::BufferEndCommand(int ch) {
 static void
 PrintCompletion(FILE *output_file,
                 llvm::ArrayRef<CompletionResult::Completion> results,
-                size_t max_len) {
+                size_t max_completion_length, size_t max_length) {
+  constexpr size_t ellipsis_length = 3;
+  constexpr size_t padding_length = 8;
+  constexpr size_t separator_length = 4;
+
+  const size_t description_col =
+      std::min(max_completion_length + padding_length, max_length);
+
   for (const CompletionResult::Completion &c : results) {
-    fprintf(output_file, "\t%-*s", (int)max_len, c.GetCompletion().c_str());
-    if (!c.GetDescription().empty())
-      fprintf(output_file, " -- %s", c.GetDescription().c_str());
-    fprintf(output_file, "\n");
+    if (c.GetCompletion().empty())
+      continue;
+    ;
+
+    // Print the leading padding.
+    fprintf(output_file, "        ");
+
+    // Print the completion with trailing padding to the description column if
+    // that fits on the screen. Otherwise print whatever fits on the screen
+    // followed by ellipsis.
+    const size_t completion_length = c.GetCompletion().size();
+    if (padding_length + completion_length < max_length) {
+      fprintf(output_file, "%-*s",
+              static_cast<int>(description_col - padding_length),
+              c.GetCompletion().c_str());
+    } else {
+      // If the completion doesn't fit on the screen, print ellipsis and don't
+      // bother with the description.
+      fprintf(output_file, "%.*s...\n\n",
+              static_cast<int>(max_length - padding_length - ellipsis_length),
+              c.GetCompletion().c_str());
+      continue;
+    }
+
+    // If we don't have a description, or we don't have enough space left to
+    // print the separator followed by the ellipsis, we're done.
+    if (c.GetDescription().empty() ||
+        description_col + separator_length + ellipsis_length >= max_length) {
+      fprintf(output_file, "\n");
+      continue;
+    }
+
+    // Print the separator.
+    fprintf(output_file, " -- ");
+
+    // Descriptions can contain newlines. We want to print them below each
+    // other, aligned after the separator. For example, foo has a
+    // two-line description:
+    //
+    // foo   -- Something that fits on the line.
+    //          More information below.
+    //
+    // However, as soon as a line exceed the available screen width and
+    // print ellipsis, we don't print the next line. For example, foo has a
+    // three-line description:
+    //
+    // foo   -- Something that fits on the line.
+    //          Something much longer  that doesn't fit...
+    //
+    // Because we had to print ellipsis on line two, we don't print the
+    // third line.
+    bool first = true;
+    for (llvm::StringRef line : llvm::split(c.GetDescription(), '\n')) {
+      if (line.empty())
+        break;
+      if (!first)
+        fprintf(output_file, "%*s",
+                static_cast<int>(description_col + separator_length), "");
+
+      first = false;
+      const size_t position = description_col + separator_length;
+      const size_t description_lenth = line.size();
----------------
labath wrote:

len**g**th

https://github.com/llvm/llvm-project/pull/116456