kstd: implement kstd::formatted_size

7 files changed, 139 insertions, 33 deletions

diff --git a/.nvim.lua b/.nvim.lua
index 14ca59ca..0f8f5119 100644
--- a/.nvim.lua
+++ b/.nvim.lua
@@ -10,7 +10,7 @@ vim.g.load_doxygen_syntax = true
 -- C++
 vim.filetype.add({
   pattern = {
-    [".*/include/kstd/.*"] = function(path, _)
+    [".*/libs/kstd/kstd/.*"] = function(path, _)
       if not path:match("%.[^/]+$") then
         return "cpp"
       end
diff --git a/libs/kstd/CMakeLists.txt b/libs/kstd/CMakeLists.txt
index 5a957573..002fb548 100644
--- a/libs/kstd/CMakeLists.txt
+++ b/libs/kstd/CMakeLists.txt
@@ -18,7 +18,7 @@ add_library("kstd::lib" ALIAS "kstd")
 target_sources("kstd" PRIVATE
     "kstd/os/error.cpp"
     "kstd/mutex.cpp"
-    "kstd/vformat.cpp"
+    "kstd/bits/format/vformat.cpp"
 )
 
 file(GLOB_RECURSE KSTD_HEADERS
diff --git a/libs/kstd/kstd/bits/format/string.hpp b/libs/kstd/kstd/bits/format/string.hpp
index e7e40886..a2b298d4 100644
--- a/libs/kstd/kstd/bits/format/string.hpp
+++ b/libs/kstd/kstd/bits/format/string.hpp
@@ -72,8 +72,7 @@ namespace kstd
   template<typename... Args>
   struct format_string
   {
-    template<std::size_t Size>
-    consteval format_string(char const (&str)[Size]) noexcept(false)  // NOLINT
+    consteval format_string(std::string_view const & str) noexcept(false)
         : str_view{str}
     {
       using namespace bits::format;
@@ -140,6 +139,11 @@ namespace kstd
       }
     }
 
+    template<std::size_t Size>
+    consteval format_string(char const (&str)[Size]) noexcept(false)  // NOLINT
+        : format_string{std::string_view{str}}
+    {}
+
     std::string_view str_view;
   };
 
diff --git a/libs/kstd/kstd/vformat.cpp b/libs/kstd/kstd/bits/format/vformat.cpp
index b7c51218..1bf293a4 100644
--- a/libs/kstd/kstd/vformat.cpp
+++ b/libs/kstd/kstd/bits/format/vformat.cpp
@@ -206,4 +206,19 @@ namespace kstd::bits::format
     return std::move(m_result);
   }
 
+  auto size_recorder::push(std::string_view text) -> void
+  {
+    m_size += text.size();
+  }
+
+  auto size_recorder::push(char) -> void
+  {
+    ++m_size;
+  }
+
+  auto size_recorder::size() const noexcept -> std::size_t
+  {
+    return m_size;
+  }
+
 }  // namespace kstd::bits::format
\ No newline at end of file
diff --git a/libs/kstd/kstd/bits/format/vformat.hpp b/libs/kstd/kstd/bits/format/vformat.hpp
index 994fae50..2db56d17 100644
--- a/libs/kstd/kstd/bits/format/vformat.hpp
+++ b/libs/kstd/kstd/bits/format/vformat.hpp
@@ -3,12 +3,13 @@
 
 // IWYU pragma: private, include <kstd/format>
 
+#include <kstd/bits/basic_string.hpp>
 #include <kstd/bits/format/args.hpp>
 #include <kstd/bits/format/output_buffer.hpp>
 #include <kstd/bits/format/string.hpp>
-#include <kstd/string>
 
 #include <algorithm>
+#include <cstddef>
 #include <iterator>
 #include <string_view>
 #include <type_traits>
@@ -29,13 +30,25 @@ namespace kstd
 
     struct string_writer : output_buffer
     {
-      auto push(std::string_view text) -> void override;
-      auto push(char character) -> void override;
+      auto push(std::string_view text) -> void final;
+      auto push(char character) -> void final;
 
-      auto release() -> string &&;
+      auto release() -> basic_string<char> &&;
 
     private:
-      string m_result{};
+      basic_string<char> m_result{};
+    };
+
+    //! A buffer that merely records the size of the output written to it.
+    struct size_recorder : output_buffer
+    {
+      auto push(std::string_view text) -> void final;
+      auto push(char character) -> void final;
+
+      [[nodiscard]] auto size() const noexcept -> std::size_t;
+
+    private:
+      std::size_t m_size{};
     };
 
     template<std::output_iterator<char> Output>
@@ -72,7 +85,8 @@ namespace kstd
   //! @param args The arguments for the format string.
   //! @return A new string containing the result of the format operation.
   template<typename... ArgumentTypes>
-  auto format(format_string<std::type_identity_t<ArgumentTypes>...> format, ArgumentTypes &&... args) -> string
+  auto format(format_string<std::type_identity_t<ArgumentTypes>...> format, ArgumentTypes &&... args)
+      -> basic_string<char>
   {
     auto buffer = bits::format::string_writer{};
     bits::format::vformat_to(buffer, format.str_view, make_format_args(std::forward<ArgumentTypes>(args)...).args);
@@ -94,6 +108,21 @@ namespace kstd
     return buffer.iterator();
   }
 
+  //! Determine the number of characters required to format the format string with the given arguments.
+  //!
+  //! @param format The format string.
+  //! @param args The arguments for the format string.
+  //! @tparam ArgumentTypes The type of the format string arguments.
+  //! @return The number of characters required to format @p format with @p args
+  template<typename... ArgumentTypes>
+  auto formatted_size(format_string<std::type_identity_t<ArgumentTypes>...> format, ArgumentTypes &&... args)
+      -> std::size_t
+  {
+    auto buffer = bits::format::size_recorder{};
+    bits::format::vformat_to(buffer, format.str_view, make_format_args(std::forward<ArgumentTypes>(args)...).args);
+    return buffer.size();
+  }
+
 }  // namespace kstd
 
 #endif
\ No newline at end of file
diff --git a/libs/kstd/kstd/format b/libs/kstd/kstd/format
index e04b79a9..5ed798db 100644
--- a/libs/kstd/kstd/format
+++ b/libs/kstd/kstd/format
@@ -1,22 +1,24 @@
 #ifndef KSTD_FORMAT_HPP
 #define KSTD_FORMAT_HPP
 
-#include <kstd/bits/format/arg.hpp>                    // IWYU pragma: export
-#include <kstd/bits/format/args.hpp>                   // IWYU pragma: export
-#include <kstd/bits/format/context.hpp>                // IWYU pragma: export
-#include <kstd/bits/format/formatter.hpp>              // IWYU pragma: export
-#include <kstd/bits/format/formatter/bool.hpp>         // IWYU pragma: export
-#include <kstd/bits/format/formatter/byte.hpp>         // IWYU pragma: export
-#include <kstd/bits/format/formatter/char.hpp>         // IWYU pragma: export
-#include <kstd/bits/format/formatter/cstring.hpp>      // IWYU pragma: export
-#include <kstd/bits/format/formatter/integral.hpp>     // IWYU pragma: export
-#include <kstd/bits/format/formatter/ordering.hpp>     // IWYU pragma: export
-#include <kstd/bits/format/formatter/pointer.hpp>      // IWYU pragma: export
-#include <kstd/bits/format/formatter/range.hpp>        // IWYU pragma: export
-#include <kstd/bits/format/formatter/string_view.hpp>  // IWYU pragma: export
-#include <kstd/bits/format/output_buffer.hpp>          // IWYU pragma: export
-#include <kstd/bits/format/parse_context.hpp>          // IWYU pragma: export
-#include <kstd/bits/format/string.hpp>                 // IWYU pragma: export
-#include <kstd/bits/format/vformat.hpp>                // IWYU pragma: export
+// IWYU pragma: begin_exports
+#include <kstd/bits/format/arg.hpp>
+#include <kstd/bits/format/args.hpp>
+#include <kstd/bits/format/context.hpp>
+#include <kstd/bits/format/formatter.hpp>
+#include <kstd/bits/format/formatter/bool.hpp>
+#include <kstd/bits/format/formatter/byte.hpp>
+#include <kstd/bits/format/formatter/char.hpp>
+#include <kstd/bits/format/formatter/cstring.hpp>
+#include <kstd/bits/format/formatter/integral.hpp>
+#include <kstd/bits/format/formatter/ordering.hpp>
+#include <kstd/bits/format/formatter/pointer.hpp>
+#include <kstd/bits/format/formatter/range.hpp>
+#include <kstd/bits/format/formatter/string_view.hpp>
+#include <kstd/bits/format/output_buffer.hpp>
+#include <kstd/bits/format/parse_context.hpp>
+#include <kstd/bits/format/string.hpp>
+#include <kstd/bits/format/vformat.hpp>
+// IWYU pragma: end_exports
 
 #endif
\ No newline at end of file
diff --git a/libs/kstd/kstd/format.test.cpp b/libs/kstd/kstd/format.test.cpp
index 624779af..6126605f 100644
--- a/libs/kstd/kstd/format.test.cpp
+++ b/libs/kstd/kstd/format.test.cpp
@@ -4,14 +4,17 @@
 
 #include <iterator>
 #include <sstream>
+#include <string_view>
+
+using namespace std::string_view_literals;
 
 SCENARIO("Formatting to a new string", "[format]")
 {
   GIVEN("a format string without any placeholders")
   {
-    auto const & fmt = "This is a test";
+    constexpr auto fmt = "This is a test"sv;
 
-    WHEN("calling format with without any arguments.")
+    WHEN("calling format without any arguments.")
     {
       auto result = kstd::format(fmt);
 
@@ -34,7 +37,7 @@ SCENARIO("Formatting to a new string", "[format]")
 
   GIVEN("a format string with placeholders")
   {
-    auto const & fmt = "Here are some placeholders: {} {} {}";
+    constexpr auto fmt = "Here are some placeholders: {} {} {}"sv;
 
     WHEN("calling format with the same number of arguments as there are placeholders")
     {
@@ -64,9 +67,9 @@ SCENARIO("Formatting to an output iterator", "[format]")
 
   GIVEN("a format string without any placeholders")
   {
-    auto const & fmt = "This is a test";
+    constexpr auto fmt = "This is a test"sv;
 
-    WHEN("calling format with without any arguments.")
+    WHEN("calling format without any arguments.")
     {
       kstd::format_to(std::ostream_iterator<char>{buffer}, fmt);
 
@@ -89,7 +92,7 @@ SCENARIO("Formatting to an output iterator", "[format]")
 
   GIVEN("a format string with placeholders")
   {
-    auto const & fmt = "Here are some placeholders: {} {} {}";
+    constexpr auto fmt = "Here are some placeholders: {} {} {}"sv;
 
     WHEN("calling format with the same number of arguments as there are placeholders")
     {
@@ -111,4 +114,57 @@ SCENARIO("Formatting to an output iterator", "[format]")
       }
     }
   }
+}
+
+SCENARIO("Determining formatted size")
+{
+  GIVEN("a format string without any placeholders")
+  {
+    constexpr auto fmt = "This is a test"sv;
+
+    WHEN("calling formatted_size without any arguments")
+    {
+      auto const size = kstd::formatted_size(fmt);
+
+      THEN("the result is equal to the length of the format string")
+      {
+        REQUIRE(size == fmt.size());
+      }
+    }
+
+    WHEN("calling format with additional arguments")
+    {
+      auto const size = kstd::formatted_size(fmt, 1, 2, 3);
+
+      THEN("the result is equal to the length of the format string")
+      {
+        REQUIRE(size == fmt.size());
+      }
+    }
+  }
+
+  GIVEN("a format string with placeholders")
+  {
+    constexpr auto fmt = "Here are some placeholders: {} {} {}"sv;
+
+    WHEN("calling format with the same number of arguments as there are placeholders")
+    {
+      auto result = kstd::formatted_size(fmt, 1, true, 'a');
+
+      THEN("the result is the formatted length")
+      {
+        REQUIRE(result == std::string_view{"Here are some placeholders: 1 true a"}.size());
+      }
+    }
+
+    WHEN("calling format with too many arguments")
+    {
+      auto result = kstd::formatted_size(fmt, 2, false, 'b', 4, 5, 6);
+
+      THEN("the result is the formatted length")
+      {
+        REQUIRE(result == std::string_view{"Here are some placeholders: 2 false b"}.size());
+      }
+    }
+  }
 }
\ No newline at end of file