Reduce and prevent unnecessary random-access to `List`

Random-access access to `List` when iterating is `O(n^2)` (`O(n)` when
accessing a single element)

* Removed subscript operator, in favor of a more explicit `get`
* Added conversion from `Iterator` to `ConstIterator`
* Remade existing operations into other solutions when applicable

3 files changed, 7 insertions, 8 deletions

diff --git a/core/debugger/debugger_marshalls.cpp b/core/debugger/debugger_marshalls.cpp
index 3e6b7501c7..f4283e0ea9 100644
--- a/core/debugger/debugger_marshalls.cpp
+++ b/core/debugger/debugger_marshalls.cpp
@@ -38,10 +38,10 @@
 Array DebuggerMarshalls::ScriptStackDump::serialize() {
 	Array arr;
 	arr.push_back(frames.size() * 3);
-	for (int i = 0; i < frames.size(); i++) {
-		arr.push_back(frames[i].file);
-		arr.push_back(frames[i].line);
-		arr.push_back(frames[i].func);
+	for (const ScriptLanguage::StackInfo &frame : frames) {
+		arr.push_back(frame.file);
+		arr.push_back(frame.line);
+		arr.push_back(frame.func);
 	}
 	return arr;
 }
diff --git a/core/debugger/remote_debugger.cpp b/core/debugger/remote_debugger.cpp
index 1973663c72..bd30da3047 100644
--- a/core/debugger/remote_debugger.cpp
+++ b/core/debugger/remote_debugger.cpp
@@ -206,8 +206,7 @@ void RemoteDebugger::flush_output() {
 		Vector<String> joined_log_strings;
 		Vector<String> strings;
 		Vector<int> types;
-		for (int i = 0; i < output_strings.size(); i++) {
-			const OutputString &output_string = output_strings[i];
+		for (const OutputString &output_string : output_strings) {
 			if (output_string.type == MESSAGE_TYPE_ERROR) {
 				if (!joined_log_strings.is_empty()) {
 					strings.push_back(String("\n").join(joined_log_strings));
diff --git a/core/debugger/remote_debugger_peer.cpp b/core/debugger/remote_debugger_peer.cpp
index 81ee09f515..21a9014626 100644
--- a/core/debugger/remote_debugger_peer.cpp
+++ b/core/debugger/remote_debugger_peer.cpp
@@ -45,7 +45,7 @@ bool RemoteDebuggerPeerTCP::has_message() {
 Array RemoteDebuggerPeerTCP::get_message() {
 	MutexLock lock(mutex);
 	ERR_FAIL_COND_V(!has_message(), Array());
-	Array out = in_queue[0];
+	Array out = in_queue.front()->get();
 	in_queue.pop_front();
 	return out;
 }
@@ -100,7 +100,7 @@ void RemoteDebuggerPeerTCP::_write_out() {
 				break; // Nothing left to send
 			}
 			mutex.lock();
-			Variant var = out_queue[0];
+			Variant var = out_queue.front()->get();
 			out_queue.pop_front();
 			mutex.unlock();
 			int size = 0;