[lldb] Reduce some dangerous boilerplate with CompletionRequest::ShiftArguments

We should in general not allow external code to fiddle with the internals of
CompletionRequest, but until this is gone let's at least provide a utility
function that makes this less dangerous.

This also now correct updates the partially parsed argument list,
but it doesn't seem to be used by anything that is behind one of
the current shift/SetCursorIndex calls, so this doesn't seeem to
fix any currently used completion.

llvm-svn: 372556

lldb/include/lldb/Utility/CompletionRequest.h

@@ -119,6 +119,13 @@ public:
     return GetParsedLine()[GetCursorIndex()];
   }
 
+  /// Drops the first argument from the argument list.
+  void ShiftArguments() {
+    m_cursor_index--;
+    m_parsed_line.Shift();
+    m_partial_parsed_line.Shift();
+  }
+
   void SetCursorIndex(int i) { m_cursor_index = i; }
   int GetCursorIndex() const { return m_cursor_index; }
 

lldb/source/Commands/CommandObjectHelp.cpp

@@ -215,8 +215,7 @@ void CommandObjectHelp::HandleCompletion(CompletionRequest &request) {
   // user is getting help on...
 
   if (cmd_obj) {
-    request.GetParsedLine().Shift();
-    request.SetCursorIndex(request.GetCursorIndex() - 1);
+    request.ShiftArguments();
     cmd_obj->HandleCompletion(request);
     return;
   }

lldb/source/Commands/CommandObjectMultiword.cpp

@@ -214,8 +214,7 @@ void CommandObjectMultiword::HandleCompletion(CompletionRequest &request) {
   // Remove the one match that we got from calling GetSubcommandObject.
   new_matches.DeleteStringAtIndex(0);
   request.AddCompletions(new_matches);
-  request.GetParsedLine().Shift();
-  request.SetCursorIndex(request.GetCursorIndex() - 1);
+  request.ShiftArguments();
   sub_command_object->HandleCompletion(request);
 }
 

lldb/source/Interpreter/CommandInterpreter.cpp

@@ -1794,8 +1794,7 @@ void CommandInterpreter::HandleCompletionMatches(CompletionRequest &request) {
     CommandObject *command_object =
         GetCommandObject(request.GetParsedLine().GetArgumentAtIndex(0));
     if (command_object) {
-      request.GetParsedLine().Shift();
-      request.SetCursorIndex(request.GetCursorIndex() - 1);
+      request.ShiftArguments();
       command_object->HandleCompletion(request);
     }
   }

lldb/unittests/Utility/CompletionRequestTest.cpp

@@ -31,6 +31,41 @@ TEST(CompletionRequest, Constructor) {
   EXPECT_STREQ(request.GetPartialParsedLine().GetArgumentAtIndex(1), "b");
 }
 
+TEST(CompletionRequest, ShiftArguments) {
+  std::string command = "a bad c";
+  const unsigned cursor_pos = 3;
+  const int arg_index = 1;
+  const int arg_cursor_pos = 1;
+  StringList matches;
+  CompletionResult result;
+
+  CompletionRequest request(command, cursor_pos, result);
+  result.GetMatches(matches);
+
+  EXPECT_STREQ(request.GetRawLine().str().c_str(), command.c_str());
+  EXPECT_EQ(request.GetRawCursorPos(), cursor_pos);
+  EXPECT_EQ(request.GetCursorIndex(), arg_index);
+  EXPECT_EQ(request.GetCursorCharPosition(), arg_cursor_pos);
+
+  EXPECT_EQ(request.GetPartialParsedLine().GetArgumentCount(), 2u);
+  EXPECT_STREQ(request.GetPartialParsedLine().GetArgumentAtIndex(1), "b");
+
+  // Shift away the 'a' argument.
+  request.ShiftArguments();
+
+  // The raw line/cursor stays identical.
+  EXPECT_STREQ(request.GetRawLine().str().c_str(), command.c_str());
+  EXPECT_EQ(request.GetRawCursorPos(), cursor_pos);
+
+  // Relative cursor position in arg is identical.
+  EXPECT_EQ(request.GetCursorCharPosition(), arg_cursor_pos);
+
+  // Partially parsed line and cursor should be updated.
+  EXPECT_EQ(request.GetCursorIndex(), arg_index - 1U);
+  EXPECT_EQ(request.GetPartialParsedLine().GetArgumentCount(), 1u);
+  EXPECT_STREQ(request.GetPartialParsedLine().GetArgumentAtIndex(0), "b");
+}
+
 TEST(CompletionRequest, DuplicateFiltering) {
   std::string command = "a bad c";
   const unsigned cursor_pos = 3;