Used std::string::front() and back() in more places

(cherry-picked from commit ed8a8a48f7)

src/config.cpp

@@ -87,8 +87,8 @@ struct config_implementation
 		config->check_valid();
 
 		assert(!parent.empty());
-		assert(parent[0] == '[');
+		assert(parent.front() == '[');
-		assert(parent[parent.size() - 1] == ']');
+		assert(parent.back() == ']');
 
 		if(config->has_child(key)) {
 			return *(config->children_.find(key)->second.front());

src/filesystem.cpp

@@ -1183,7 +1183,7 @@ void binary_paths_manager::set_paths(const config& cfg)
 			continue;
 		}
 
-		if(!path.empty() && path[path.size() - 1] != '/')
+		if(!path.empty() && path.back() != '/')
 			path += "/";
 		if(binary_paths.count(path) == 0) {
 			binary_paths.insert(path);

src/formula/function.cpp

@@ -1368,7 +1368,7 @@ formula_function_expression::formula_function_expression(const std::string& name
 	, star_arg_(-1)
 {
 	for(std::size_t n = 0; n != arg_names_.size(); ++n) {
-		if(arg_names_.empty() == false && arg_names_[n][arg_names_[n].size() - 1] == '*') {
+		if(arg_names_.empty() == false && arg_names_[n].back() == '*') {
 			arg_names_[n].resize(arg_names_[n].size() - 1);
 			star_arg_ = n;
 			break;

src/gui/dialogs/wml_error.cpp

@@ -37,7 +37,7 @@ namespace
 
 void strip_trailing_dir_separators(std::string& str)
 {
-	while(filesystem::is_path_sep(str[str.size() - 1])) {
+	while(filesystem::is_path_sep(str.back())) {
 		str.erase(str.size() - 1);
 	}
 }

src/preferences/credentials.cpp

@@ -109,7 +109,7 @@ namespace preferences
 		std::string name = preferences::get("login", EMPTY_LOGIN);
 		if(name == EMPTY_LOGIN) {
 			name = get_system_username();
-		} else if(name.size() > 2 && name[0] == '@' && name[name.size() - 1] == '@') {
+		} else if(name.size() > 2 && name.front() == '@' && name.back() == '@') {
 			name = name.substr(1, name.size() - 2);
 		} else {
 			ERR_CFG << "malformed user credentials (did you manually edit the preferences file?)" << std::endl;

src/scripting/lua_kernel_base.cpp

@@ -258,7 +258,7 @@ static int intf_wml_matches_filter(lua_State* L)
 static int intf_log(lua_State *L) {
 	const std::string& logger = lua_isstring(L, 2) ? luaL_checkstring(L, 1) : "";
 	std::string msg = lua_isstring(L, 2) ? luaL_checkstring(L, 2) : luaL_checkstring(L, 1);
-	if(msg.empty() || msg[msg.size() - 1] != '\n') {
+	if(msg.empty() || msg.back() != '\n') {
 		msg += '\n';
 	}
 

src/units/unit.cpp

@@ -1879,7 +1879,7 @@ void unit::apply_builtin_effect(std::string apply_to, const config& effect)
 		const bool violate_max = effect["violate_maximum"].to_bool();
 
 		if(!set_hp.empty()) {
-			if(set_hp[set_hp.size()-1] == '%') {
+			if(set_hp.back() == '%') {
 				hit_points_ = lexical_cast_default<int>(set_hp)*max_hit_points_/100;
 			} else {
 				hit_points_ = lexical_cast_default<int>(set_hp);
@@ -1887,7 +1887,7 @@ void unit::apply_builtin_effect(std::string apply_to, const config& effect)
 		}
 
 		if(!set_total.empty()) {
-			if(set_total[set_total.size()-1] == '%') {
+			if(set_total.back() == '%') {
 				max_hit_points_ = lexical_cast_default<int>(set_total)*max_hit_points_/100;
 			} else {
 				max_hit_points_ = lexical_cast_default<int>(set_total);
@@ -1953,7 +1953,7 @@ void unit::apply_builtin_effect(std::string apply_to, const config& effect)
 		const std::string& set = effect["set"];
 
 		if(!set.empty()) {
-			if(set[set.size()-1] == '%') {
+			if(set.back() == '%') {
 				experience_ = lexical_cast_default<int>(set)*max_experience_/100;
 			} else {
 				experience_ = lexical_cast_default<int>(set);
@@ -1968,7 +1968,7 @@ void unit::apply_builtin_effect(std::string apply_to, const config& effect)
 		const std::string& set = effect["set"];
 
 		if(set.empty() == false) {
-			if(set[set.size()-1] == '%') {
+			if(set.back() == '%') {
 				max_experience_ = lexical_cast_default<int>(set)*max_experience_/100;
 			} else {
 				max_experience_ = lexical_cast_default<int>(set);
@@ -2131,7 +2131,7 @@ void unit::apply_builtin_effect(std::string apply_to, const config& effect)
 		const int recall_cost = recall_cost_ < 0 ? resources::gameboard->teams().at(side_).recall_cost() : recall_cost_;
 
 		if(!set.empty()) {
-			if(set[set.size()-1] == '%') {
+			if(set.back() == '%') {
 				recall_cost_ = lexical_cast_default<int>(set)*recall_cost/100;
 			} else {
 				recall_cost_ = lexical_cast_default<int>(set);

src/utils/markov_generator.cpp

@@ -81,9 +81,9 @@ static std::u32string markov_generate_name(const markov_prefix_map& prefixes,
 		}
 
 		res.resize(res.size()+1);
-		res[res.size()-1] = c;
+		res.back() = c;
 		prefix.resize(prefix.size()+1);
-		prefix[prefix.size()-1] = c;
+		prefix.back() = c;
 		while(prefix.size() > chain_size) {
 			prefix.erase(prefix.begin());
 		}