tessera/ratph6.tessera.api/MixinContext

MixinContext

class MixinContext(val target: String, val method: String, val self: Any?, val args: Array<Any?>)

The object handed to a Mixin injection callback. It is the live link between the running Minecraft method and the script: read the receiver and arguments, cancel the call, or substitute its return value.

import { Mixin } from 'ratph6.tessera.api';

// Stop the player from ever taking fall damage.
Mixin.inject("net.minecraft.world.entity.LivingEntity", "causeFallDamage", "HEAD", (ctx) => {
  ctx.cancel();                 // skip the original method body
});

// Force a method that returns a boolean to always return true.
Mixin.inject("net.minecraft.client.player.LocalPlayer", "isSprinting", "RETURN", (ctx) => {
  ctx.setReturnValue(true);
});

The self receiver and the boxed args mirror the target method's signature (primitive arguments arrive boxed, e.g. an int becomes a java.lang.Integer). args is read-only — mutating elements does not change the values the original method sees.

The field-access surface (cancelled, returnValue, hasReturnOverride) is read directly by the bytecode Tessera injects into the target method, so the names and descriptors here are an ABI — keep them in sync with MixinTransformer.

Constructors

MixinContext

constructor(target: String, method: String, self: Any?, args: Array<Any?>)

Properties

args

@JvmField

val args: Array<Any?>

The target method's arguments, boxed. Read-only.

cancelled

@JvmField

var cancelled: Boolean

Set by cancel/setReturnValue; read by the injected bytecode to short-circuit the method.

hasReturnOverride

@JvmField

var hasReturnOverride: Boolean

True once setReturnValue has been called — tells the injected bytecode to use returnValue.

method

@JvmField

val method: String

Name of the injected method.

returnValue

@JvmField

var returnValue: Any?

At a RETURN injection this starts as the method's actual return value; setReturnValue replaces it.

self

@JvmField

val self: Any?

The receiver (this) of the call, or null for a static method.

target

@JvmField

val target: String

Binary name of the injected class, e.g. net.minecraft.client.Minecraft.

Functions

argCount

fun argCount(): Int

cancel

fun cancel()

Skip the rest of the original method (a HEAD injection returns immediately).

getArg

fun getArg(i: Int): Any?

The i-th argument (boxed), or null if out of range.

isCancelled

fun isCancelled(): Boolean

setReturnValue

fun setReturnValue(value: Any?)

Substitute the method's return value. At a HEAD injection this also cancels the original body; at a RETURN injection it replaces the value about to be returned. The value must be assignable to the method's declared return type (an unbox/checkcast happens in the injected bytecode).