Added CharSequence.isEmpty() replacement

Author: RaphiMC

src/main/java/net/raphimc/javadowngrader/transformer/j14/Java15ToJava14.java

@@ -18,12 +18,16 @@
 package net.raphimc.javadowngrader.transformer.j14;
 
 import net.raphimc.javadowngrader.transformer.DowngradingTransformer;
+import net.raphimc.javadowngrader.transformer.j14.methodcallreplacer.CharSequenceIsEmptyMCR;
 import org.objectweb.asm.Opcodes;
 
 public class Java15ToJava14 extends DowngradingTransformer {
 
     public Java15ToJava14() {
         super(Opcodes.V15, Opcodes.V14);
+
+        this.addMethodCallReplacer(Opcodes.INVOKEINTERFACE, "java/lang/CharSequence", "isEmpty", "()Z", new CharSequenceIsEmptyMCR());
+        this.addMethodCallReplacer(Opcodes.INVOKEVIRTUAL, "java/lang/StringBuilder", "isEmpty", "()Z", new CharSequenceIsEmptyMCR());
     }
 
 }

src/main/java/net/raphimc/javadowngrader/transformer/j14/methodcallreplacer/CharSequenceIsEmptyMCR.java

@@ -0,0 +1,54 @@
+/*
+ * This file is part of JavaDowngrader - https://github.com/RaphiMC/JavaDowngrader
+ * Copyright (C) 2023 RK_01/RaphiMC and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package net.raphimc.javadowngrader.transformer.j14.methodcallreplacer;
+
+import net.raphimc.javadowngrader.transformer.MethodCallReplacer;
+import org.objectweb.asm.Opcodes;
+import org.objectweb.asm.tree.*;
+
+public class CharSequenceIsEmptyMCR implements MethodCallReplacer {
+
+    @Override
+    public InsnList getReplacement(ClassNode classNode, MethodNode method, String originalName, String originalDesc) {
+        final InsnList replacement = new InsnList();
+
+        LabelNode ifNeq = new LabelNode();
+        LabelNode end = new LabelNode();
+
+        // CharSequence
+        replacement.add(new MethodInsnNode(Opcodes.INVOKEINTERFACE, "java/lang/CharSequence", "length", "()I"));
+        // int
+        replacement.add(new InsnNode(Opcodes.ICONST_0));
+        // int, int
+        replacement.add(new JumpInsnNode(Opcodes.IF_ICMPNE, ifNeq));
+
+        //
+        replacement.add(new InsnNode(Opcodes.ICONST_1));
+        // int
+        replacement.add(new JumpInsnNode(Opcodes.GOTO, end));
+
+        //
+        replacement.add(ifNeq);
+        replacement.add(new InsnNode(Opcodes.ICONST_0));
+        // int
+        replacement.add(end);
+
+        return replacement;
+    }
+
+}