====== Redirecting methods ======

Method redirectors can use the following [[https://github.com/SpongePowered/Mixin/wiki/Injection-Point-Reference|injection point references]]:

  * ''INVOKE''; and
  * ''INVOKE_STRING''.

===== INVOKE =====

The ''INVOKE'' injection point reference is used for invocations of ''target'' in ''method'', which means that it can be used in order to redirect a method immediately before it is called.

==== Redirecting a static method ====

Static method redirectors should have the same parameters as the ''target''.

redirecting the ''ItemStack::fromTag(ListTag)'' call in ''SimpleInventory::readTags'' to return ''null'':

<code java [enable_line_numbers=true]>
@Mixin(SimpleInventory.class)
abstract class SimpleInventoryMixin {
    @Redirect(method = "readTags",
              at = @At(value = "INVOKE_ASSIGN", target = "Lnet/minecraft/item/ItemStack;fromTag(Lnet/minecraft/nbt/ListTag;)Lnet/minecraft/item/ItemStack;"))
    private static ItemStack returnNull(ListTag tag) {
        return null;
    }
}
</code>

==== Redirecting an instance method ====

Instance method redirectors are similar to static methood redirectors, but they should have an additional parameter at the start of their parameter lists for the objects on which their ''target''s are invoked.

redirecting the ''Entity::dropItem(ItemConvertible, int)'' call in ''Entity::dropItem(ItemConvertible)'' to remove diamonds instead of dropping them by replacing them with air:

<code java [enable_line_numbers=true]>
@Mixin(Entity.class)
abstract class EntityMixin {
    @Redirect(method = "dropItem",
              at = @At(value = "INVOKE", target = "Lnet/minecraft/item/ItemStack;dropItem(Lnet/minecraft/item/ItemConvertible;I)Lnet/minecraft/entity/ItemEntity;"))
    private ItemEntity replaceDroppedItem(Entity droppingEntity, ItemConvertible item, int yOffset) {
        return droppingEntity.dropItem(item == Items.DIAMOND ? Items.AIR : item, yOffset);
    }
}
</code>

===== INVOKE_STRING =====

The ''INVOKE_STRING'' injection point reference is used for matching invocations of ''target'' in ''method'' if ''target'' is a method with a single ''String'' parameter and a ''String'' literal is passed to it. The ''String'' literal to capture should be specified in the ''args'' property of ''At''.

redirecting the ''Profiler::push'' invocation with ''"tick"'' passed to it in ''MinecraftClient::render'' in order to modify the ''location'' passed in the said invocation:

<code java [enable_line_numbers=true]>
@Mixin(MinecraftClient.class)
abstract class MinecraftClientMixin {
    @Redirect(method = "render",
              at = @At(value = "INVOKE_STRING",
                       target = "Lnet/minecraft/util/profiler/Profiler;push(Ljava/lang/String;)V",
                       args = "ldc=tick"))
    private void redirectPush(Profiler profiler, String location) {
        profiler.push("modified tick");
        System.out.println(location);
    }
}
</code>