A series of cursed Fabric hacks and utilities which break everything.
There are many use cases for direct ASM injections and the power to re-transform every loaded class.
This is basically a cleanup rewrite of GrossFabricHacks using the ClassTransform and Reflect libraries.
It also provides the same functionality as MixinSquared.
If you encounter any issues, please report them on theissue tracker.
If you just want to talk or need help with AsmFabricLoader feel free to join myDiscord.
To use BaseProject with Gradle/Maven you can use Maven Central, Lenni0451's Maven or Jitpack.
You can also find instructions how to implement it into your build script there.
If you just want the latest jar file you can download it from the GitHub Actions or use the Release.
AsmFabricLoader allows you to access a series of utilities and hacks to make your life easier.
AsmFabricLoader adds an even more early entry point than FabricMC's PreLaunchEntrypoint.
You can use the PrePreLaunchEntrypoint, which will be called when Fabric bootstraps the mixin service. The name
of the entry point is afl:prePreLaunch.
The PrePrePreLaunchEntrypoint is the earliest entry point possible. It is getting bootstrapped before the loader
even starts. The name of the entry point is afl:prePrePreLaunch.
You can use both just like the PreLaunchEntrypoint from FabricMC.
AsmFabricLoader allows you to get a Java instrumentation instance which you can use to transform classes directly.
You can use the InstrumentationEntrypoint to get the instrumentation instance. The name of the entry point is
afl:instrumentation.
FabricLoader 0.15.0+ removed the tiny-mappings-parser library and therefore most of the mappings API. AsmFabricLoader
re-adds the mappings API and allows you to use it in your mods.
final MappingsResolver mappings = AsmFabricLoader.getLoader().getMappingsResolver();
if (mappings.areMappingsLoaded()) { // This will be true in production environments
// Now you get the mapping path you want to translate to, for example:
final String className=mappings.named().getClassName("net/minecraft/class_7833");
// this field should now be net/minecraft/util/math/RotationAxis
// You can also use the getClassDef method to get a ClassDef object from the tiny-mappings-parser library
final ClassDef classDef = mappings.named().getClassDef("net/minecraft/class_7833");
}AsmFabricLoader adds a new API which allows you to unload Mixin classes meaning they aren't injected anymore. This is useful if another mod is breaking your Mixins or if you want to unload Mixins after they have been applied.
final Unmixer unmixer = AsmFabricLoader.getLoader().getUnmixer();
// This method accepts the mixin classes of all loaded mods including the Fabric internals
unmixer.unloadMixinClass("net/fabricmc/api/mixin/v1/MixinEnvironment");You can also use the Unmixer via the fabric.mod.json file:
{
"custom": {
"afl:unmixer": [
"net.fabricmc.api.mixin.v1.MixinEnvironment"
]
}
}You can also group the packages together:
{
"custom": {
"afl:unmixer": {
"net.fabricmc.api.mixin.v1": [
"MixinEnvironment"
]
}
}
}AsmFabricLoader allows you to define a list of folders where it will load all jar files from to the front of the classpath. This can be useful if you want to allow the user to replace a library jar file you are using with a different version.
{
"custom": {
"afl:jarbooter": [
"libs"
]
}
}This will load all jar files from the run directory/libs folder to the front of the classpath.
Utility to create and invoke mod entrypoints before Fabric has finished loading entrypoints. See the EarlyRiser class
AsmFabricLoader bootstraps the ClassTransform library which allows you to transform classes directly without using Mixins.
You just have to create a json file called <modid>.classtransform.json in your resources folder and add the following
{
"package": "net.example.injection.transformer",
"java": [
],
"mixins": [
]
}The package field is the package where your transformers are located.
Now AsmFabricLoader provides two ways to add transformers to the ClassTransform library:
The java field will apply all the transformers using a runtime injected java agent after Mixins and the loader
has been initialized. Meaning you can transform all classes in your runtime, even Java standard library classes.
The mixins field will apply all the transformers before Mixins are getting applied, therefore you can only add
transformers targeting other mods mixin classes. These transformers will be applied before those Mixins are getting
applied to the game code, this is basically a replacement for MixinSquared.
@CTransformer(String.class)
public class Test {
@CInline
@CInject(method = "equals", target = @CTarget("HEAD"))
public void printInput(Object anObject, InjectionCallback callback) {
System.out.println("Input: " + anObject);
}
}To register your json file, you have to add the following to your fabric.mod.json file:
{
"custom": {
"afl:classtransform": "<modid>.classtransform.json"
}
}AsmFabricLoader allows you to limit the execution of all the features to specific environments. This can be useful if you want to use the same mod jar file for multiple environments.
This snippet will only apply the unmixer if the mod is loaded on the client:
{
"custom": {
"afl:client:unmixer": [
]
}
}There are a few system properties you can enable to debug AsmFabricLoader:
-DAsmFabricLoader.debug=true will print a lot of useful debug information including loading states
-Dclasstransform.dumpClasses= will dump all classes transformed by ClassTransform
to run directory / classtransform
The TestMod submodule contains a Fabric mod to test various features of AsmFabricLoader. You can run the tests by
building both root project and the test mod project and then running them in a production environment.
A test running successfully will be indicated by the following message in the console:
[TestMod] <NameOfTheTest> passed!
All tests have been passed if you see the following message in the console:
[TestMod] All tests passed!