Add missing #include <optional> to charls.ixx (#311)

.gitattributes

@@ -1,3 +1,6 @@
+# Copyright (c) Team CharLS.
+# SPDX-License-Identifier: BSD-3-Clause
+
 # Set default behavior to automatically normalize line endings.
 * text=auto
 
@@ -17,8 +20,8 @@
 *.pgm binary
 
 # Export ignore all files that are only needed for git and CI (used when downloading the repository as a zip file).
+.github export-ignore
 .gitattributes export-ignore
 .gitignore export-ignore
-.travis.yml export-ignore
-.appveyor.yml export-ignore
-azure-pipelines.yml export-ignore
+appveyor.yml export-ignore
+azure-pipelines.yml export-ignore

.gitignore

@@ -1,4 +1,5 @@
-# GIT ignore file for CharLS
+# Copyright (c) Team CharLS.
+# SPDX-License-Identifier: BSD-3-Clause
 
 .vscode/
 .vs/
@@ -19,12 +20,5 @@ vcpkg_installed/
 *.aps
 *.sqlite
 
-# NuGet Packages
-*.nupkg
-# The packages folder can be ignored because of Package Restore
-**/packages/*
-# except build/, which is used as an MSBuild target.
-!**/packages/build/
-
 # Ignore Coverity build folder
 cov-int/

doc/style_and_design.md

@@ -130,31 +130,32 @@ sense to define a good naming convention. Not all JPEG-LS names are good C++ var
 
 ### Supported C++ language
 
-CharLS currently targets C++17 on the main branch. This will be done until December 2025 (5 years after the release of C++20)
-
-#### Features currently not available (C++17)
-
-* nodiscard attribute
-* maybe_unused attribute
-* Inline variables
-* Guaranteed copy elision
-* constexpr if-statements
-* __has_include
-* std::byte
-* clamp ?
+CharLS currently targets C++17 on the main branch. Upgrading to C++20 will be done when C++20 is used in
+mainstream C++ development.
 
 #### Features currently not available (C++20)
 
-The following features are available in C++20 (usable after 2023), or in dual language support mode.
+The following features are available in C++20, or in dual language support mode.
 
 * endian
 * \<span>
 * modules
+* [[likely]] and [[unlikely]]
+* std::countl_zero
+
+#### Features currently not available (C++23)
+
+The following features are available in C++23, or in dual language support mode.
+
+* std::byteswap
+* import std;
+* std::to_underlying
+* std::unreachable
 
 ### Portable Anymap Format
 
 The de facto standard used by the JPEG standard to deliver test files is the Portable Anymap Format.
-This format has been made populair by the netpbm project. It is an extreme simple format and only
+This format has been made popular by the netpbm project. It is an extreme simple format and only
 designed to make it easy to exchange images on many platforms.
 It consists of the following variants
 

include/charls/charls.ixx

@@ -12,6 +12,7 @@ module;
 #include <functional>
 #include <memory>
 #include <utility>
+#include <optional>
 
 export module charls;
 

src/jpeg_stream_reader.cpp

@@ -458,27 +458,28 @@ void jpeg_stream_reader::read_preset_coding_parameters()
 void jpeg_stream_reader::read_oversize_image_dimension()
 {
     // Note: The JPEG-LS standard supports a 2,3 or 4 bytes for the size.
-    check_minimal_segment_size(2);
+    constexpr size_t pc_and_dimension_bytes{2};
+    check_minimal_segment_size(pc_and_dimension_bytes);
     const uint8_t dimension_size{read_uint8()};
 
     uint32_t height;
     uint32_t width;
     switch (dimension_size)
     {
     case 2:
-        check_segment_size(sizeof(uint16_t) * 2 + 2);
+        check_segment_size(pc_and_dimension_bytes + sizeof(uint16_t) * 2);
         height = read_uint16();
         width = read_uint16();
         break;
 
     case 3:
-        check_segment_size((sizeof(uint16_t) + 1) * 2 + 2);
+        check_segment_size(pc_and_dimension_bytes + (sizeof(uint16_t) + 1) * 2);
         height = read_uint24();
         width = read_uint24();
         break;
 
     case 4:
-        check_segment_size(sizeof(uint32_t) * 2 + 2);
+        check_segment_size(pc_and_dimension_bytes + sizeof(uint32_t) * 2);
         height = read_uint32();
         width = read_uint32();
         break;
@@ -494,22 +495,24 @@ void jpeg_stream_reader::read_oversize_image_dimension()
 
 void jpeg_stream_reader::read_mapping_table_specification()
 {
-    check_minimal_segment_size(3);
+    constexpr size_t pc_table_id_entry_size_bytes{3};
+    check_minimal_segment_size(pc_table_id_entry_size_bytes);
     const uint8_t table_id{read_uint8()};
     const uint8_t entry_size{read_uint8()};
 
-    add_mapping_table(table_id, entry_size, segment_data_.subspan(3));
+    add_mapping_table(table_id, entry_size, segment_data_.subspan(pc_table_id_entry_size_bytes));
     skip_remaining_segment_data();
 }
 
 
 void jpeg_stream_reader::read_mapping_table_continuation()
 {
-    check_minimal_segment_size(3);
+    constexpr size_t pc_table_id_entry_size_bytes{3};
+    check_minimal_segment_size(pc_table_id_entry_size_bytes);
     const uint8_t table_id{read_uint8()};
     const uint8_t entry_size{read_uint8()};
 
-    extend_mapping_table(table_id, entry_size, segment_data_.subspan(3));
+    extend_mapping_table(table_id, entry_size, segment_data_.subspan(pc_table_id_entry_size_bytes));
     skip_remaining_segment_data();
 }