add return 系列字节码指令的抽象类

src/main/java/haidnor/jvm/core/JavaExecutionEngine.java

@@ -102,8 +102,8 @@ public class JavaExecutionEngine {
             try {
                 // 执行字节码指令
                 instruction.execute(frame);
-                // 若为 return 系列指令则结束当前栈帧
+                // 若为 return 系列指令则结束当前栈帧 (RETURN,ARETURN,DRETURN,FRETURN,IRETURN)
-                if (instruction instanceof RETURN || instruction instanceof ARETURN || instruction instanceof DRETURN || instruction instanceof FRETURN || instruction instanceof IRETURN) {
+                if (instruction instanceof ReturnableInstruction) {
                     break;
                 }
                 // 程序计数器值增加. 指向下一次执行的字节码行号

src/main/java/haidnor/jvm/instruction/control/ARETURN.java

@@ -1,12 +1,11 @@
 package haidnor.jvm.instruction.control;
 
-import haidnor.jvm.instruction.Instruction;
 import haidnor.jvm.runtime.Frame;
 import haidnor.jvm.runtime.StackValue;
 import haidnor.jvm.util.CodeStream;
 import haidnor.jvm.util.JvmThreadHolder;
 
-public class ARETURN extends Instruction {
+public class ARETURN extends ReturnableInstruction {
 
     public ARETURN(CodeStream codeStream) {
         super(codeStream);

src/main/java/haidnor/jvm/instruction/control/DRETURN.java

@@ -1,12 +1,11 @@
 package haidnor.jvm.instruction.control;
 
-import haidnor.jvm.instruction.Instruction;
 import haidnor.jvm.runtime.Frame;
 import haidnor.jvm.runtime.StackValue;
 import haidnor.jvm.util.CodeStream;
 import haidnor.jvm.util.JvmThreadHolder;
 
-public class DRETURN extends Instruction {
+public class DRETURN extends ReturnableInstruction {
 
     public DRETURN(CodeStream codeStream) {
         super(codeStream);

src/main/java/haidnor/jvm/instruction/control/FRETURN.java

@@ -1,12 +1,11 @@
 package haidnor.jvm.instruction.control;
 
-import haidnor.jvm.instruction.Instruction;
 import haidnor.jvm.runtime.Frame;
 import haidnor.jvm.runtime.StackValue;
 import haidnor.jvm.util.CodeStream;
 import haidnor.jvm.util.JvmThreadHolder;
 
-public class FRETURN extends Instruction {
+public class FRETURN extends ReturnableInstruction {
 
     public FRETURN(CodeStream codeStream) {
         super(codeStream);

src/main/java/haidnor/jvm/instruction/control/IRETURN.java

@@ -1,12 +1,11 @@
 package haidnor.jvm.instruction.control;
 
-import haidnor.jvm.instruction.Instruction;
 import haidnor.jvm.runtime.Frame;
 import haidnor.jvm.runtime.StackValue;
 import haidnor.jvm.util.CodeStream;
 import haidnor.jvm.util.JvmThreadHolder;
 
-public class IRETURN extends Instruction {
+public class IRETURN extends ReturnableInstruction {
 
     public IRETURN(CodeStream codeStream) {
         super(codeStream);

src/main/java/haidnor/jvm/instruction/control/LRETURN.java

@@ -1,12 +1,11 @@
 package haidnor.jvm.instruction.control;
 
-import haidnor.jvm.instruction.Instruction;
 import haidnor.jvm.runtime.Frame;
 import haidnor.jvm.runtime.StackValue;
 import haidnor.jvm.util.CodeStream;
 import haidnor.jvm.util.JvmThreadHolder;
 
-public class LRETURN extends Instruction {
+public class LRETURN extends ReturnableInstruction {
 
     public LRETURN(CodeStream codeStream) {
         super(codeStream);

src/main/java/haidnor/jvm/instruction/control/RETURN.java

@@ -1,11 +1,10 @@
 package haidnor.jvm.instruction.control;
 
-import haidnor.jvm.instruction.Instruction;
 import haidnor.jvm.runtime.Frame;
 import haidnor.jvm.util.CodeStream;
 import haidnor.jvm.util.JvmThreadHolder;
 
-public class RETURN extends Instruction {
+public class RETURN extends ReturnableInstruction {
 
     public RETURN(CodeStream codeStream) {
         super(codeStream);

src/main/java/haidnor/jvm/instruction/control/ReturnableInstruction.java

@@ -0,0 +1,15 @@
+package haidnor.jvm.instruction.control;
+
+import haidnor.jvm.instruction.Instruction;
+import haidnor.jvm.util.CodeStream;
+
+/**
+ * return 系列字节码指令的抽象类
+ */
+public abstract class ReturnableInstruction extends Instruction {
+
+    public ReturnableInstruction(CodeStream codeStream) {
+        super(codeStream);
+    }
+
+}