nothrow variants for strings format

headers/enduro2d/utils/strings.hpp

@@ -51,7 +51,18 @@ namespace e2d
             str_view fmt, Args&&... args);
 
         template < typename... Args >
-        str rformat(str_view fmt, Args&&... args);
+        bool format_nothrow(
+            char* dst, std::size_t dst_size, std::size_t* length,
+            str_view fmt, Args&&... args) noexcept;
+
+        template < typename... Args >
+        str rformat(
+            str_view fmt, Args&&... args);
+
+        template < typename... Args >
+        bool rformat_nothrow(
+            str& dst,
+            str_view fmt, Args&&... args) noexcept;
 
         bool wildcard_match(str_view string, str_view pattern);
     }

headers/enduro2d/utils/strings.inl

@@ -385,6 +385,23 @@ namespace e2d { namespace strings
             std::make_tuple(impl::wrap_arg(std::forward<Args>(args))...));
     }
 
+    template < typename... Args >
+    bool format_nothrow(
+        char* dst, std::size_t dst_size, std::size_t* length,
+        str_view fmt, Args&&... args) noexcept
+    {
+        try {
+            std::size_t result = format(
+                dst, dst_size, fmt, std::forward<Args>(args)...);
+            if ( length ) {
+                *length = result;
+            }
+            return true;
+        } catch (...) {
+            return false;
+        }
+    }
+
     template < typename... Args >
     str rformat(str_view fmt, Args&&... args) {
         auto targs = std::make_tuple(
@@ -397,6 +414,16 @@ namespace e2d { namespace strings
         E2D_ASSERT(expected_format_size == actual_format_size);
         return str(buffer.data(), buffer.data() + actual_format_size);
     }
+
+    template < typename... Args >
+    bool rformat_nothrow(str& dst, str_view fmt, Args&&... args) noexcept {
+        try {
+            dst = rformat(fmt, std::forward<Args>(args)...);
+            return true;
+        } catch (...) {
+            return false;
+        }
+    }
 }}
 
 #endif

untests/sources/untests_utils/strings.cpp

@@ -250,6 +250,18 @@ TEST_CASE("strings") {
         REQUIRE_THROWS_AS(strings::rformat("hell%y%"), strings::bad_format);
         REQUIRE_THROWS_AS(strings::rformat("%z%hell"), strings::bad_format);
     }
+    {
+        str s;
+        REQUIRE(strings::rformat_nothrow(s, "%0", "hello"));
+        REQUIRE(s == "hello");
+        REQUIRE_FALSE(strings::rformat_nothrow(s, "%"));
+        char buf[5] = {0};
+        std::size_t length = 0;
+        REQUIRE(strings::format_nothrow(buf, E2D_COUNTOF(buf), &length, "%0", "hell"));
+        REQUIRE(length == 4);
+        REQUIRE(str(buf) == str("hell"));
+        REQUIRE_FALSE(strings::format_nothrow(buf, E2D_COUNTOF(buf), &length, "%0", "hello"));
+    }
     {
         REQUIRE(strings::rformat(str_view("%0"), 42) == "42");
         REQUIRE(strings::rformat(str_view("%0%1",2), 42) == "42");