6841419: classfile: add constant pool iterator

Reviewed-by: mcimadamore

langtools/src/share/classes/com/sun/tools/classfile/ClassTranslator.java

@@ -95,7 +95,7 @@ public class ClassTranslator
         if (cp2 == null) {
             ConstantPool.CPInfo[] pool2 = new ConstantPool.CPInfo[cp.size()];
             boolean eq = true;
-            for (int i = 0; i < cp.size(); i++) {
+            for (int i = 0; i < cp.size(); ) {
                 ConstantPool.CPInfo cpInfo;
                 try {
                     cpInfo = cp.get(i);
@@ -107,11 +107,7 @@ public class ClassTranslator
                 pool2[i] = cpInfo2;
                 if (cpInfo.getTag() != cpInfo2.getTag())
                     throw new IllegalStateException();
-                switch (cpInfo.getTag()) {
+                i += cpInfo.size();
-                    case ConstantPool.CONSTANT_Double:
-                    case ConstantPool.CONSTANT_Long:
-                        i += 1;
-                }
             }
 
             if (eq)

langtools/src/share/classes/com/sun/tools/classfile/ClassWriter.java

@@ -118,13 +118,8 @@ public class ClassWriter {
         ConstantPool pool = classFile.constant_pool;
         int size = pool.size();
         out.writeShort(size);
-        try {
+        for (CPInfo cpInfo: pool.entries())
-            for (int i = 1; i < size; ) {
+            constantPoolWriter.write(cpInfo, out);
-                i += constantPoolWriter.write(pool.get(i), out);
-            }
-        } catch (ConstantPoolException e) {
-            throw new Error(e); // ??
-        }
     }
 
     protected void writeFields() throws IOException {

langtools/src/share/classes/com/sun/tools/classfile/ConstantPool.java

@@ -26,6 +26,7 @@
 package com.sun.tools.classfile;
 
 import java.io.IOException;
+import java.util.Iterator;
 
 /**
  * See JVMS3, section 4.5.
@@ -223,6 +224,40 @@ public class ConstantPool {
         throw new EntryNotFound(value);
     }
 
+    public Iterable<CPInfo> entries() {
+        return new Iterable<CPInfo>() {
+            public Iterator<CPInfo> iterator() {
+                return new Iterator<CPInfo>() {
+
+                    public boolean hasNext() {
+                        return next < pool.length;
+                    }
+
+                    public CPInfo next() {
+                        current = pool[next];
+                        switch (current.getTag()) {
+                            case CONSTANT_Double:
+                            case CONSTANT_Long:
+                                next += 2;
+                                break;
+                            default:
+                                next += 1;
+                        }
+                        return current;
+                    }
+
+                    public void remove() {
+                        throw new UnsupportedOperationException();
+                    }
+
+                    private CPInfo current;
+                    private int next = 1;
+
+                };
+            }
+        };
+    }
+
     private CPInfo[] pool;
 
     public interface Visitor<R,P> {
@@ -250,6 +285,12 @@ public class ConstantPool {
 
         public abstract int getTag();
 
+        /** The number of slots in the constant pool used by this entry.
+         * 2 for CONSTANT_Double and CONSTANT_Long; 1 for everything else. */
+        public int size() {
+            return 1;
+        }
+
         public abstract <R,D> R accept(Visitor<R,D> visitor, D data);
 
         protected final ConstantPool cp;
@@ -349,6 +390,11 @@ public class ConstantPool {
             return CONSTANT_Double;
         }
 
+        @Override
+        public int size() {
+            return 2;
+        }
+
         @Override
         public String toString() {
             return "CONSTANT_Double_info[value: " + value + "]";
@@ -462,6 +508,11 @@ public class ConstantPool {
             return CONSTANT_Long;
         }
 
+        @Override
+        public int size() {
+            return 2;
+        }
+
         @Override
         public String toString() {
             return "CONSTANT_Long_info[value: " + value + "]";