Codechange: replace C-style (stredup) chat completion with std::string_view

src/network/network_chat_gui.cpp

@@ -323,18 +323,16 @@ struct NetworkChatWindow : public Window {
 	 * Find the next item of the list of things that can be auto-completed.
 	 * @param item The current indexed item to return. This function can, and most
 	 *     likely will, alter item, to skip empty items in the arrays.
-	 * @return Returns the char that matched to the index.
+	 * @return Returns the view that matched to the index.
 	 */
-	const char *ChatTabCompletionNextItem(uint *item)
+	std::optional<std::string> ChatTabCompletionNextItem(uint *item)
 	{
-		static char chat_tab_temp_buffer[64];
-
 		/* First, try clients */
 		if (*item < MAX_CLIENT_SLOTS) {
 			/* Skip inactive clients */
 			for (NetworkClientInfo *ci : NetworkClientInfo::Iterate(*item)) {
 				*item = ci->index;
-				return ci->client_name.c_str();
+				return ci->client_name;
 			}
 			*item = MAX_CLIENT_SLOTS;
 		}
@@ -346,12 +344,11 @@ struct NetworkChatWindow : public Window {
 			for (const Town *t : Town::Iterate(*item - MAX_CLIENT_SLOTS)) {
 				/* Get the town-name via the string-system */
 				SetDParam(0, t->index);
-				GetString(chat_tab_temp_buffer, STR_TOWN_NAME, lastof(chat_tab_temp_buffer));
+				return GetString(STR_TOWN_NAME);
-				return &chat_tab_temp_buffer[0];
 			}
 		}
 
-		return nullptr;
+		return std::nullopt;
 	}
 
 	/**
@@ -359,13 +356,14 @@ struct NetworkChatWindow : public Window {
 	 *  the word right from that as to complete. It also writes a \0 at the
 	 *  position of the space (if any). If nothing found, buf is returned.
 	 */
-	static char *ChatTabCompletionFindText(char *buf)
+	static std::string_view ChatTabCompletionFindText(std::string_view &buf)
 	{
-		char *p = strrchr(buf, ' ');
+		auto it = buf.find_last_of(' ');
-		if (p == nullptr) return buf;
+		if (it == std::string_view::npos) return buf;
 
-		*p = '\0';
+		std::string_view res = buf.substr(it + 1);
-		return p + 1;
+		buf.remove_suffix(res.size() + 1);
+		return res;
 	}
 
 	/**
@@ -373,46 +371,44 @@ struct NetworkChatWindow : public Window {
 	 */
 	void ChatTabCompletion()
 	{
-		static char _chat_tab_completion_buf[NETWORK_CHAT_LENGTH];
+		static std::string _chat_tab_completion_buf;
-		assert(this->message_editbox.text.max_bytes == lengthof(_chat_tab_completion_buf));
 
 		Textbuf *tb = &this->message_editbox.text;
-		size_t len, tb_len;
+		uint item = 0;
-		uint item;
-		char *tb_buf, *pre_buf;
-		const char *cur_name;
 		bool second_scan = false;
 
-		item = 0;
+		/* Create views, so we do not need to copy the data for now. */
+		std::string_view pre_buf = _chat_tab_completion_active ? std::string_view(_chat_tab_completion_buf) : std::string_view(tb->buf);
+		std::string_view tb_buf = ChatTabCompletionFindText(pre_buf);
 
-		/* Copy the buffer so we can modify it without damaging the real data */
+		/*
-		pre_buf = (_chat_tab_completion_active) ? stredup(_chat_tab_completion_buf) : stredup(tb->buf);
+		 * Comparing pointers of the data, as both "Hi:<tab>" and "Hi: Hi:<tab>" will result in
+		 * tb_buf and pre_buf being "Hi:", which would be equal in content but not in context.
+		 */
+		bool begin_of_line = tb_buf.data() == pre_buf.data();
 
-		tb_buf  = ChatTabCompletionFindText(pre_buf);
+		std::optional<std::string> cur_item;
-		tb_len  = strlen(tb_buf);
+		while ((cur_item = ChatTabCompletionNextItem(&item)).has_value()) {
-
+			std::string_view cur_name = cur_item.value();
-		while ((cur_name = ChatTabCompletionNextItem(&item)) != nullptr) {
 			item++;
 
 			if (_chat_tab_completion_active) {
 				/* We are pressing TAB again on the same name, is there another name
 				 *  that starts with this? */
 				if (!second_scan) {
-					size_t offset;
+					std::string_view view;
-					size_t length;
 
 					/* If we are completing at the begin of the line, skip the ': ' we added */
-					if (tb_buf == pre_buf) {
+					if (begin_of_line) {
-						offset = 0;
+						view = std::string_view(tb->buf, (tb->bytes - 1) - 2);
-						length = (tb->bytes - 1) - 2;
 					} else {
 						/* Else, find the place we are completing at */
-						offset = strlen(pre_buf) + 1;
+						size_t offset = pre_buf.size() + 1;
-						length = (tb->bytes - 1) - offset;
+						view = std::string_view(tb->buf + offset, (tb->bytes - 1) - offset);
 					}
 
 					/* Compare if we have a match */
-					if (strlen(cur_name) == length && strncmp(cur_name, tb->buf + offset, length) == 0) second_scan = true;
+					if (cur_name == view) second_scan = true;
 
 					continue;
 				}
@@ -420,21 +416,19 @@ struct NetworkChatWindow : public Window {
 				/* Now any match we make on _chat_tab_completion_buf after this, is perfect */
 			}
 
-			len = strlen(cur_name);
+			if (tb_buf.size() < cur_name.size() && StrStartsWith(cur_name, tb_buf)) {
-			if (tb_len < len && StrStartsWith(cur_name, tb_buf)) {
 				/* Save the data it was before completion */
-				if (!second_scan) seprintf(_chat_tab_completion_buf, lastof(_chat_tab_completion_buf), "%s", tb->buf);
+				if (!second_scan) _chat_tab_completion_buf = tb->buf;
 				_chat_tab_completion_active = true;
 
 				/* Change to the found name. Add ': ' if we are at the start of the line (pretty) */
-				if (pre_buf == tb_buf) {
+				if (begin_of_line) {
 					this->message_editbox.text.Assign(fmt::format("{}: ", cur_name));
 				} else {
 					this->message_editbox.text.Assign(fmt::format("{} {}", pre_buf, cur_name));
 				}
 
 				this->SetDirty();
-				free(pre_buf);
 				return;
 			}
 		}
@@ -446,7 +440,6 @@ struct NetworkChatWindow : public Window {
 
 			this->SetDirty();
 		}
-		free(pre_buf);
 	}
 
 	Point OnInitialPosition(int16 sm_width, int16 sm_height, int window_number) override