https://github.com/zxshady/enchantum
A Faster Enum Reflection For C++20 Since I Don't Want To Wait For C++26 Reflection
https://github.com/zxshady/enchantum
c-plus-plus cpp cpp20 enum enum-to-string header-only is-bitflag-enum metaprogramming no-dependencies reflection reflection-library serialization string-to-enum templates
Last synced: 4 days ago
JSON representation
A Faster Enum Reflection For C++20 Since I Don't Want To Wait For C++26 Reflection
- Host: GitHub
- URL: https://github.com/zxshady/enchantum
- Owner: ZXShady
- License: mit
- Created: 2025-04-17T03:16:02.000Z (2 months ago)
- Default Branch: main
- Last Pushed: 2025-06-10T05:00:08.000Z (7 days ago)
- Last Synced: 2025-06-10T05:30:07.275Z (7 days ago)
- Topics: c-plus-plus, cpp, cpp20, enum, enum-to-string, header-only, is-bitflag-enum, metaprogramming, no-dependencies, reflection, reflection-library, serialization, string-to-enum, templates
- Language: C++
- Homepage:
- Size: 402 KB
- Stars: 45
- Watchers: 2
- Forks: 5
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# Enchantum
**Enchantum** (short for "enchant enum") is a modern **C++20** header-only library for **compile-time enum reflection**. It provides fast, lightweight access to enum values, names, and bitflags all without macros or boilerplate.
> Every year, countless turtles perish due to the pollution caused by slow, bloated build times.
Save the turtles — and your compile times — by switching to enchantum!
Source: I made it up.
Key Features
- Macro-free and non-intrusive boilerplate-free reflection
- Fast compile times (benchmarked below)
- Most efficient binary size wise.
- Supports:
- Scoped enums
- Unscoped C enums
- Sparse enums
- Bitflags
- Iteration over values,names and `[enum, name]` pairs.
- `string <=> enum` conversions
- `enum <=> index` conversions
- enum validation functions like `cast` and `contains`
- enum aware containers: `enchantum::bitset` and `enchantum::array`
- Extra features like:
- Optional null terminator disabling
- Optional prefix stripping for C-style enums
- `0` values are reflected for bitflag enums
[Simple Examples](#simple-examples)
[Why another enum reflection library?](#why-another-enum-reflection-library)
[Features](docs/features.md)
[Benchmarks](#benchmarks)
[Limitations](docs/limitations.md)
[CMake Integration](#cmake-integration)
Tested locally on Windows 10 with:
- Visual Studio 2022 (v17.13.6)
- GCC 14.2.0
- Clang 20.1.2
Compiler Support: (Look at [CI](https://github.com/ZXShady/enchantum/actions))
- GCC >= 11 (GCC 10 Partial no support for enums in templates)
- Clang >= 10
---
> [!IMPORTANT]
> Be sure to read [Limitations](docs/limitations.md) before using Enchantum in production.
## Simple Examples
Enums used in the examples
* to string
```cpp
#include // to_string
#include // ostream support
enum class Music { Rock, Jazz , Metal };
int main()
{
auto music = Music::Rock;
std::string_view music_name = enchantum::to_string(music);
// music_name == "Rock"
using namespace enchantum::ostream_operators;
std::cout << music;
// Prints Rock
}
```
* from strings
```cpp
#include // cast
enum class Music { Rock, Jazz , Metal };
int main()
{
// case sensitive
std::optional music = enchantum::cast("Jazz");
if(music.has_value()) // check if cast succeeded
{
// *music == Music::Jazz
}
// pass a predicate taking two string views
music = enchantum::cast("JAZZ",[](std::string_view a,std::string_view b){
return std::ranges::equal(a,b,[](unsigned char x,unsigned char y){
return std::tolower(x) == std::tolower(y);
});
});
if(music.has_value()) {
// *music == Music::Jazz
}
}
```
* index into enums
```cpp
#include // index_to_enum and enum_to_index
enum class Music { Rock, Jazz , Metal };
int main()
{
// case sensitive
std::optional music = enchantum::index_to_enum(1); // Jazz is the second enum member
if(music.has_value()) // check if index is not out of bounds
{
// *music == Music::Jazz
std::optional index = enchantum::enum_to_index(*music);
// *index == 1
}
}
```
* iteration
```cpp
#include // entries,values and names
enum class Music { Rock, Jazz , Metal };
int main()
{
// Iterate over values
for(Music music : enchantum::values)
std::cout << static_cast(music) << " ";
// Prints "0 1 2"
// Iterate over names
for(std::string_view name : enchantum::names)
std::cout << name << " ";
// Prints "Rock Jazz Metal"
// Iterate over both!
for(const auto& [music,name] : enchantum::entries)
std::cout << name << " = " << static_cast(music) << "\n";
// Prints
// Rock = 0
// Jazz = 1
// Metal = 2
}
```
Look at [Features](docs/features.md) for more information.
## Why Another Enum Reflection Library?
There are several enum reflection libraries out there — so why choose **enchantum** instead of [magic_enum](https://github.com/Neargye/magic_enum), [simple_enum](https://github.com/arturbac/simple_enum), or [conjure_enum](https://github.com/fix8mt/conjure_enum)?
### magic_enum
**Pros**
- Macro-free (non intrusive).
- No modifications needed for existing enums.
- Allows specifying ranges for specific enums when needed.
- Supports C++17.
- Nicer compiler errors.
- Supports wide strings.
- Efficient executable binary size.
**Cons**
- Compile times grow significantly with larger `MAGIC_ENUM_MAX_RANGE`.
- Bigger Binary Size.
### conjure_enum
**Pros**
- Macro-free (non intrusive)
- Uses C++20
**Cons**
*Note: Could not get this to compile locally. Based on the README, compile times are similar to or worse than magic_enum.*
### simple_enum
**Pros**
- Fast compile times but only if range is small.
- Functor based api.
**Cons**
- Requires specifying enum `first`/`last` values manually (intrusive, doesn't work well with third-party enums)
- Compile time slows down with large enum ranges
- Big Binary Size Bloat.
- No support for bitflags yet.
### enchantum
**Pros**
- Macro-free (non intrusive)
- Does not sacrifice API ease of use and features for compile time sake (e.g no `ENCHANTUM_ALL_ENUMS_ARE_CONTIGUOUS_OPTIMIZATION` flag which would disable support for sparse enums)
- Allows specifying ranges for specific enums when needed
- Compiles fast.
- Clean and Simple Functor based API `enchantum::to_string(E)` no `enchantum::to_string()` since compile times are fast.
- Features like disabling null termination if not needed and specifying common enum prefix for C style enums, and reflect '0' values for bit flag enums.
- Supports all sort of enums (scoped,unscoped,C style unfixed underlying type,anonymous namespaced enums, enums with commas in their typename,etc...);
- Efficient object binary size and executable size.
**Cons**
- C++20 required
- Compiler errors are incomprehensible if something goes wrong, needs a level 10 wizard to read them.
- No support for wide strings (yet)
---
## Benchmarks
Each compile time benchmark was run 10 times and averaged unless noted otherwise.
`range` is `ENCHANTUM_MAX_RANGE` and `MAGIC_ENUM_RANGE_MAX`, for `simple_enum` it is defining `last` and `first` with the range because I could not find a macro for this, this is technically misuse of the library since it likes having these values close to the actual range but the comparisons would be unfair.
The enum members are from 0 to Count
| Test Case | Small | Big | Large Range | Ideal Range |
|-----------------|------------|--------------|-------------|-------------|
| Number of Enums | 200 | 32 | 200 | 100 |
| Enum Range | (-128,128) | (-256,256) | (-1024,1024)| (0,50) |
| Values per Enum | 16 | 200 | 16 | 50 |
### Compile Time
All times in **seconds** (lower is better). Compiled with `-O3` fir GCC and Clang while `/Ox` for MSVC.
**Note**: "Timeout" means it took more than 20 minutes and still did not finish
| Compiler | Test Case | `enchantum` | `magic_enum` | `simple_enum` |
|-------------|-------------|--------------| ------------ |---------------|
| **GCC** | Small | 6.1 | 47 | 21.5 |
| | Big | 4.5 | 21 | 6.3 |
| | Large Range | 26.7 | Timeout | 313 |
| | Ideal Range | 3 | 8.1 | 2.7 |
| |
| **Clang** | Small | 6.2 | 47 | 14 |
| | Big | 3.5 | 18 | 4.4 |
| | Large Range | 22.3 | Timeout | 96.3 |
| | Ideal Range | 3 | 8.7 | 2.3 |
| |
| **MSVC** | Small | 15.8 | 80 | 186 |
| | Big | 8.8 | 37 | 32.1 |
| | Large Range | 85.3 | Timeout | Timeout |
| | Ideal Range | 5.8 | 17.9 | 4.7 |
## Object File Sizes
Lower is better
[A simple godbolt link for magic_enum vs enchantum](https://godbolt.org/#g:!((g:!((h:output,i:(editorid:1,fontScale:14,fontUsePx:'0',j:1,wrap:'1'),l:'5',n:'0',o:'Output+of+x86-64+clang+(trunk)+(Compiler+%231)',t:'0'),(h:compiler,i:(compiler:clang_trunk,filters:(b:'0',binary:'1',binaryObject:'1',commentOnly:'0',debugCalls:'1',demangle:'0',directives:'0',execute:'1',intel:'0',libraryCode:'0',trim:'1',verboseDemangling:'0'),flagsViewOpen:'1',fontScale:14,fontUsePx:'0',j:1,lang:c%2B%2B,libs:!(),options:'-O3+-DENCH%3D0+-std%3Dc%2B%2B20',overrides:!(),selection:(endColumn:1,endLineNumber:1,positionColumn:1,positionLineNumber:1,selectionStartColumn:1,selectionStartLineNumber:1,startColumn:1,startLineNumber:1),source:1),l:'5',n:'0',o:'+x86-64+clang+(trunk)+(Editor+%231)',t:'0'),(h:codeEditor,i:(filename:'1',fontScale:14,fontUsePx:'0',j:1,lang:c%2B%2B,selection:(endColumn:1,endLineNumber:16,positionColumn:1,positionLineNumber:16,selectionStartColumn:1,selectionStartLineNumber:16,startColumn:1,startLineNumber:16),source:'%23if+ENCH%0A%23include+%3Chttps://raw.githubusercontent.com/ZXShady/enchantum/refs/heads/main/single_include/enchantum_single_header.hpp%3E%0A%23define+magic_enum+enchantum%0A%23define+enum_name+to_string%0A%23else%0A%23define+MAGIC_ENUM_RANGE_MIN+-500%0A%23define+MAGIC_ENUM_RANGE_MAX+500%0A%23include+%3Chttps://raw.githubusercontent.com/Neargye/magic_enum/refs/heads/master/include/magic_enum/magic_enum.hpp%3E%0A%23endif%0Aenum+class+A+%7Balong,b,c,e,d,f,glong%7D%3B%0Aextern+A+enm%3B%0A%0Aint+main()+%7B%0A++++return+magic_enum::enum_name(enm).size()%3B%0A%7D%0A'),l:'5',n:'0',o:'C%2B%2B+source+%231',t:'0')),header:(),l:'4',m:100,n:'0',o:'',s:2,t:'0')),version:4)
Clang is only currently measured. But GCC produced same sizes almost
| Compiler | Test Case | `enchantum` | `magic_enum` | `simple_enum` |
|-------------|-------------|--------------| ------------ |---------------|
| **Clang** | Small | 447 KB | 1132 KB | 3773 KB |
| | Big | 249 KB | 1368 KB | ~12000 KB |
| | Large Range | 504 KB | Unknown | ~96000 KB |
| | Ideal Range | 465 KB | 1091 KB | 1253 KB |
**Note**:
The reason `simple_enum` is so big in object sizes is that it generates a huge table of all strings it does not do string optimizations like `enchantum` or `magic_enum` which leads to big object sizes there are a lot of useless strings in the binary but it also allows the library to do `O(1)` enum to string lookup for **any** enum, which I don't necessarily think is worth it and compile faster.
### Executable Sizes
Compiled the object files into their own executable then ran `strip` over them.
| Compiler | Test Case | `enchantum` | `magic_enum` | `simple_enum` |
|-------------|-------------|--------------| ------------ |---------------|
| **Clang** | Small | 106 KB | 106 KB | 2996 KB |
| | Big | 182 KB | 182 KB | 959 KB |
| | Large Range | 106 KB | Unknown | ~23000 KB |
| | Ideal Range | 147 KB | 147 KB | 323 KB |
**Remarks**: although magic enum did not compile in the large range test, the executable size is expected to be the same as enchantum given it optimizes strings.
---
## Summary
**enchantum** significantly reduces compile times and object sizes in enum reflection projects. In my own project (which uses [libassert](https://github.com/jeremy-rifkin/libassert) and enum reflection for configuration), switching from `magic_enum` reduced full rebuild times from about 2 minutes to 1 minute and 26 seconds. I was surprised that `magic_enum` alone took 34 seconds.
I also tried compiling my project using -2048,2048 as my range and it took 1 minute and 46 seconds! that's still less than `magic_enum` by default while having **16x** the default range.
The trade-off is that `enchantum` requires C++20, while `magic_enum` supports C++17.
But this requirement can be lifted if there is enough demand for a C++17 version of `enchantum`.
# CMake Integration
The **cmake** file provides the target `enchantum::enchantum` since this library is header-only it is very simple to use you can copy and paste the files and add the include directory or use **cmake** and the library as a submodule.
```cpp
add_subdirectory("third_party/enchantum")
target_link_libraries(your_executable enchantum::enchantum)
```