[lldb] Display autosuggestion part in gray if there is one possible suggestion

I implemented autosuggestion if there is one possible suggestion.
I set the keybinds for every character. When a character is typed, Editline::TypedCharacter is called.
Then, autosuggestion part is displayed in gray, and you can actually input by typing C-k.
Editline::Autosuggest is a function for finding completion, and it is like Editline::TabCommand now, but I will add more features to it.

Testing does not work well in my environment, so I can't confirm that it goes well, sorry. I am dealing with it now.

Reviewed By: teemperor, JDevlieghere, #lldb

Differential Revision: https://reviews.llvm.org/D81001

1 files changed, 13 insertions, 0 deletions

diff --git a/lldb/source/Interpreter/CommandInterpreter.cpp b/lldb/source/Interpreter/CommandInterpreter.cpp
index 4786e46..ec82efb 100644
--- a/lldb/source/Interpreter/CommandInterpreter.cpp
+++ b/lldb/source/Interpreter/CommandInterpreter.cpp
@@ -1878,6 +1878,19 @@ void CommandInterpreter::HandleCompletion(CompletionRequest &request) {
   HandleCompletionMatches(request);
 }
 
+llvm::Optional<std::string>
+CommandInterpreter::GetAutoSuggestionForCommand(llvm::StringRef line) {
+  if (line.empty())
+    return llvm::None;
+  const size_t s = m_command_history.GetSize();
+  for (int i = s - 1; i >= 0; --i) {
+    llvm::StringRef entry = m_command_history.GetStringAtIndex(i);
+    if (entry.consume_front(line))
+      return entry.str();
+  }
+  return llvm::None;
+}
+
 CommandInterpreter::~CommandInterpreter() {}
 
 void CommandInterpreter::UpdatePrompt(llvm::StringRef new_prompt) {