[lldb] Use CompletionRequest in REPL::CompleteCode and remove translation code to old API

Any REPL client should just move to CompletionRequest instead of relying on
the translation code from the old API, so let's remove that translation code.

Author: Teemperor

lldb/include/lldb/Expression/REPL.h

@@ -130,8 +130,8 @@ class REPL : public IOHandlerDelegate {
                                 lldb::ValueObjectSP &valobj_sp,
                                 ExpressionVariable *var = nullptr) = 0;
 
-  virtual int CompleteCode(const std::string &current_code,
-                           StringList &matches) = 0;
+  virtual void CompleteCode(const std::string &current_code,
+                            CompletionRequest &request) = 0;
 
   OptionGroupFormat m_format_options = OptionGroupFormat(lldb::eFormatDefault);
   OptionGroupValueObjectDisplay m_varobj_options;

lldb/source/Expression/REPL.cpp

@@ -488,14 +488,7 @@ void REPL::IOHandlerComplete(IOHandler &io_handler,
   current_code.append("\n");
   current_code += request.GetRawLine();
 
-  StringList matches;
-  int result = CompleteCode(current_code, matches);
-  if (result == -2) {
-    assert(matches.GetSize() == 1);
-    request.AddCompletion(matches.GetStringAtIndex(0), "",
-                          CompletionMode::RewriteLine);
-  } else
-    request.AddCompletions(matches);
+  CompleteCode(current_code, request);
 }
 
 bool QuitCommandOverrideCallback(void *baton, const char **argv) {