Mantle/src/mantle/event/Migration.java

package mantle.event;

import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import cpw.mods.fml.common.Mod;
import cpw.mods.fml.common.ModContainer;
import cpw.mods.fml.common.event.FMLMissingMappingsEvent;
import cpw.mods.fml.common.event.FMLMissingMappingsEvent.MissingMapping;
import cpw.mods.fml.common.eventhandler.SubscribeEvent;
import net.minecraft.block.Block;
import net.minecraft.item.Item;

import java.util.List;
import java.util.Map;

public abstract class Migration
{
    Map<String, Item> remapItem = Maps.newHashMap();
    Map<String, Block> remapBlock = Maps.newHashMap();
    List<String> ignore = Lists.newArrayList();
    private ModContainer mod;

    private String modID;

    /*
     * Store the mod ID so we can convert e.g "item" to "mod:item" later.
     */
    public Migration(ModContainer m)
    {
        m.getModId();
    }

    /*
     * Add a new migration to the internal replacement map e.g. "olditem" -> "newitem" (without ID prefix!).
     * Use an encapsulated object of form Map<String,Item> to store this.
     * The prefix will be created using the ID given during construction during processing.
     */
    public void addMigration (String old, Item newItem)
    {
        remapItem.put(modID + ":" + old, newItem);
    }

    /*
    * Add a new migration to the internal replacement map e.g. "olditem" -> "newitem" (without ID prefix!).
    * Use an encapsulated object of form Map<String,Block> to store this.
    * The prefix will be created using the ID given during construction during processing.
    */
    public void addMigration (String old, Block newBlock)
    {
        remapBlock.put(modID + ":" + old, newBlock);
    }
    /*
     * Register an old ID that's been removed entirely. This isn't suitable for renaming operations!
     * Store this in a List<String> seperate to the rename mapping.
     * @param id ID to be removed (without ID prefix!).
     */
    public void addRemoval (String id)
    {
        ignore.add(modID + ":" + id);
    };

    /*
     * This must be called from your mod's main class as it requires @EventHandler notation
     * This works on the assumption the FML event will have a list of string IDs that are missing.
     * During this phase, check for old IDs and remap as needed, or destroy ones marked for removal.
     */
    public void processMigrationEvent (FMLMissingMappingsEvent event) {
        if (!remapBlock.isEmpty() || !remapItem.isEmpty()) {
            event.applyModContainer(mod);
            for (MissingMapping miss : event.get()) {
                if(remapItem.containsKey(miss.name))
                    miss.remap(remapItem.get(miss.name));
                else if(remapBlock.containsKey(miss.name))
                    miss.remap(remapBlock.get(miss.name));
                else if(ignore.contains(miss.name))
                    miss.ignore();
            }
        }
    }
}