Add FieldRedirectTransformer updated to new modlauncher API

src/fmllauncher/java/net/minecraftforge/common/asm/FieldRedirectTransformer.java

@@ -0,0 +1,125 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016-2018.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.common.asm;
+
+import java.util.EnumSet;
+import java.util.ListIterator;
+
+import org.objectweb.asm.Opcodes;
+import org.objectweb.asm.Type;
+import org.objectweb.asm.tree.AbstractInsnNode;
+import org.objectweb.asm.tree.ClassNode;
+import org.objectweb.asm.tree.FieldInsnNode;
+import org.objectweb.asm.tree.FieldNode;
+import org.objectweb.asm.tree.MethodInsnNode;
+import org.objectweb.asm.tree.MethodNode;
+
+import cpw.mods.modlauncher.serviceapi.ILaunchPluginService;
+
+public abstract class FieldRedirectTransformer implements ILaunchPluginService
+{
+    private final String clsName;
+    private final String TYPE;
+    private final String DESC;
+    private final String bypass;
+
+    protected FieldRedirectTransformer(String cls, String type, String bypass)
+    {
+        this.clsName = cls;
+        this.TYPE = type;
+        this.DESC = "()" + type;
+        this.bypass = bypass;
+    }
+    
+    private static final EnumSet<Phase> YAY = EnumSet.of(Phase.AFTER);
+    private static final EnumSet<Phase> NAY = EnumSet.noneOf(Phase.class);
+    
+    @Override
+    public EnumSet<Phase> handlesClass(Type classType, boolean isEmpty)
+    {
+        return classType.getClassName().equals(clsName) && !isEmpty ? YAY : NAY;
+    }
+    
+    @Override
+    public boolean processClass(Phase phase, ClassNode classNode, Type classType)
+    {
+        FieldNode fieldRef = null;
+        for (FieldNode f : classNode.fields)
+        {
+            if (this.TYPE.equals(f.desc) && fieldRef == null)
+            {
+                fieldRef = f;
+            }
+            else if (this.TYPE.equals(f.desc))
+            {
+                throw new RuntimeException("Error processing " + clsName + " - found a duplicate holder field");
+            }
+        }
+        if (fieldRef == null)
+        {
+            throw new RuntimeException("Error processing " + clsName + " - no holder field declared (is the code somehow obfuscated?)");
+        }
+
+        MethodNode getMethod = null;
+        for (MethodNode m: classNode.methods)
+        {
+            if (m.name.equals(this.bypass)) continue;
+            if (this.DESC.equals(m.desc) && getMethod == null)
+            {
+                getMethod = m;
+            }
+            else if (this.DESC.equals(m.desc))
+            {
+                throw new RuntimeException("Error processing " + clsName + " - duplicate get method found");
+            }
+        }
+        if (getMethod == null)
+        {
+            throw new RuntimeException("Error processing " + clsName + " - no get method found (is the code somehow obfuscated?)");
+        }
+
+        for (MethodNode m: classNode.methods)
+        {
+            if (m.name.equals(this.bypass)) continue;
+            for (ListIterator<AbstractInsnNode> it = m.instructions.iterator(); it.hasNext(); )
+            {
+                AbstractInsnNode insnNode = it.next();
+                if (insnNode.getType() == AbstractInsnNode.FIELD_INSN)
+                {
+                    FieldInsnNode fi = (FieldInsnNode)insnNode;
+                    if (fieldRef.name.equals(fi.name) && fi.getOpcode() == Opcodes.GETFIELD)
+                    {
+                        it.remove();
+                        MethodInsnNode replace = new MethodInsnNode(Opcodes.INVOKEVIRTUAL, classNode.name, getMethod.name, getMethod.desc, false);
+                        it.add(replace);
+                    }
+                }
+            }
+        }
+        
+        return true;
+    }
+
+    @Override
+    public String name()
+    {
+        return "field_redirect_" + clsName + "/" + TYPE;
+    }
+}