php-java · chitoku-k · May 10, 2019 · May 7, 2019 · May 8, 2019 · May 8, 2019
diff --git a/src/Core/JVM/ConstantPool.php b/src/Core/JVM/ConstantPool.php
@@ -19,6 +19,7 @@
 use PHPJava\Kernel\Structures\_NameAndType;
 use PHPJava\Kernel\Structures\_String;
 use PHPJava\Kernel\Structures\_Utf8;
+use PHPJava\Kernel\Structures\FreezableInterface;
 use PHPJava\Kernel\Structures\StructureInterface;
 
 class ConstantPool implements \ArrayAccess, \Countable, \IteratorAggregate
@@ -108,6 +109,9 @@ public function offsetExists($offset)
      */
     public function offsetGet($offset)
     {
+        if ($this->entries[$offset] instanceof FreezableInterface) {
+            $this->entries[$offset]->freeze();
+        }
         return $this->entries[$offset];
     }
 

diff --git a/src/Core/JVM/Intern/InternInterface.php b/src/Core/JVM/Intern/InternInterface.php
diff --git a/src/Core/JVM/Intern/StringIntern.php b/src/Core/JVM/Intern/StringIntern.php
diff --git a/src/Core/JavaClassInvoker.php b/src/Core/JavaClassInvoker.php
@@ -2,11 +2,9 @@
 namespace PHPJava\Core;
 
 use PHPJava\Core\JVM\DynamicAccessor;
-use PHPJava\Core\JVM\Intern\StringIntern;
 use PHPJava\Core\JVM\StaticAccessor;
 use PHPJava\Exceptions\IllegalJavaClassException;
 use PHPJava\Kernel\Maps\FieldAccessFlag;
-use PHPJava\Kernel\Provider\InternProvider;
 use PHPJava\Kernel\Provider\ProviderInterface;
 use PHPJava\Kernel\Structures\_FieldInfo;
 use PHPJava\Kernel\Structures\_MethodInfo;
@@ -82,15 +80,6 @@ public function __construct(
             }
         }
 
-        // Intern provider registration.
-        $this->providers = [
-            'InternProvider' => (new InternProvider())
-                ->add(
-                    StringIntern::class,
-                    new StringIntern()
-                ),
-        ];
-
         $this->dynamicAccessor = new DynamicAccessor(
             $this,
             $this->dynamicMethods,

diff --git a/src/Kernel/Mnemonics/_aload.php b/src/Kernel/Mnemonics/_aload.php
@@ -1,8 +1,6 @@
 <?php
 namespace PHPJava\Kernel\Mnemonics;
 
-use PHPJava\Core\JVM\Intern\StringIntern;
-
 final class _aload implements OperationInterface
 {
     use \PHPJava\Kernel\Core\Accumulator;
@@ -14,10 +12,6 @@ final class _aload implements OperationInterface
     public function execute(): void
     {
         $index = $this->readByte();
-        $stringIntern = $this->javaClassInvoker
-            ->getProvider('InternProvider')
-            ->get(StringIntern::class);
-        $internedValue = $stringIntern[spl_object_id($this->getLocalStorage($index))] ?? null;
-        $this->pushToOperandStack($internedValue ?: $this->getLocalStorage($index));
+        $this->pushToOperandStack($this->getLocalStorage($index));
     }
 }
diff --git a/src/Kernel/Mnemonics/_aload_0.php b/src/Kernel/Mnemonics/_aload_0.php
@@ -1,8 +1,6 @@
 <?php
 namespace PHPJava\Kernel\Mnemonics;
 
-use PHPJava\Core\JVM\Intern\StringIntern;
-
 final class _aload_0 implements OperationInterface
 {
     use \PHPJava\Kernel\Core\Accumulator;
@@ -14,10 +12,6 @@ final class _aload_0 implements OperationInterface
     public function execute(): void
     {
         $index = 0;
-        $stringIntern = $this->javaClassInvoker
-            ->getProvider('InternProvider')
-            ->get(StringIntern::class);
-        $internedValue = $stringIntern[spl_object_id($this->getLocalStorage($index))] ?? null;
-        $this->pushToOperandStack($internedValue ?: $this->getLocalStorage($index));
+        $this->pushToOperandStack($this->getLocalStorage($index));
     }
 }
diff --git a/src/Kernel/Mnemonics/_aload_1.php b/src/Kernel/Mnemonics/_aload_1.php
@@ -1,8 +1,6 @@
 <?php
 namespace PHPJava\Kernel\Mnemonics;
 
-use PHPJava\Core\JVM\Intern\StringIntern;
-
 final class _aload_1 implements OperationInterface
 {
     use \PHPJava\Kernel\Core\Accumulator;
@@ -14,10 +12,6 @@ final class _aload_1 implements OperationInterface
     public function execute(): void
     {
         $index = 1;
-        $stringIntern = $this->javaClassInvoker
-            ->getProvider('InternProvider')
-            ->get(StringIntern::class);
-        $internedValue = $stringIntern[spl_object_id($this->getLocalStorage($index))] ?? null;
-        $this->pushToOperandStack($internedValue ?: $this->getLocalStorage($index));
+        $this->pushToOperandStack($this->getLocalStorage($index));
     }
 }
diff --git a/src/Kernel/Mnemonics/_aload_2.php b/src/Kernel/Mnemonics/_aload_2.php
@@ -1,8 +1,6 @@
 <?php
 namespace PHPJava\Kernel\Mnemonics;
 
-use PHPJava\Core\JVM\Intern\StringIntern;
-
 final class _aload_2 implements OperationInterface
 {
     use \PHPJava\Kernel\Core\Accumulator;
@@ -14,10 +12,6 @@ final class _aload_2 implements OperationInterface
     public function execute(): void
     {
         $index = 2;
-        $stringIntern = $this->javaClassInvoker
-            ->getProvider('InternProvider')
-            ->get(StringIntern::class);
-        $internedValue = $stringIntern[spl_object_id($this->getLocalStorage($index))] ?? null;
-        $this->pushToOperandStack($internedValue ?: $this->getLocalStorage($index));
+        $this->pushToOperandStack($this->getLocalStorage($index));
     }
 }
diff --git a/src/Kernel/Mnemonics/_aload_3.php b/src/Kernel/Mnemonics/_aload_3.php
@@ -1,8 +1,6 @@
 <?php
 namespace PHPJava\Kernel\Mnemonics;
 
-use PHPJava\Core\JVM\Intern\StringIntern;
-
 final class _aload_3 implements OperationInterface
 {
     use \PHPJava\Kernel\Core\Accumulator;
@@ -14,10 +12,6 @@ final class _aload_3 implements OperationInterface
     public function execute(): void
     {
         $index = 3;
-        $stringIntern = $this->javaClassInvoker
-            ->getProvider('InternProvider')
-            ->get(StringIntern::class);
-        $internedValue = $stringIntern[spl_object_id($this->getLocalStorage($index))] ?? null;
-        $this->pushToOperandStack($internedValue ?: $this->getLocalStorage($index));
+        $this->pushToOperandStack($this->getLocalStorage($index));
     }
 }
diff --git a/src/Kernel/Provider/InternProvider.php b/src/Kernel/Provider/InternProvider.php
diff --git a/src/Kernel/Structures/FreezableInterface.php b/src/Kernel/Structures/FreezableInterface.php
@@ -0,0 +1,8 @@
+<?php
+
+namespace PHPJava\Kernel\Structures;
+
+interface FreezableInterface
+{
+    public function freeze(): void;
+}
diff --git a/src/Kernel/Structures/_Utf8.php b/src/Kernel/Structures/_Utf8.php
@@ -1,14 +1,16 @@
 <?php
 namespace PHPJava\Kernel\Structures;
 
-class _Utf8 implements StructureInterface
+class _Utf8 implements StructureInterface, FreezableInterface
 {
     use \PHPJava\Kernel\Core\BinaryReader;
     use \PHPJava\Kernel\Core\ConstantPool;
     use \PHPJava\Kernel\Core\DebugTool;
 
     private $length = 0;
     private $string = '';
+    private $isWritable;
+    private $isFrozen = false;
 
     /**
      * @var \PHPJava\Packages\java\lang\_String $stringObject
@@ -24,23 +26,46 @@ public function execute(): void
         $this->stringObject = new \PHPJava\Packages\java\lang\_String($this);
     }
 
-    public function getLength()
+    public function getLength(): int
     {
         return $this->length;
     }
 
-    public function getString()
+    public function enableWrite(bool $enable): self
     {
-        return $this->string;
+        if (!$this->isFrozen) {
+            $this->isWritable = $enable;
+        }
+        return $this;
     }
 
-    public function __toString(): string
+    public function freeze(): void
     {
-        return $this->getString();
+        $this->isFrozen = true;
+        $this->enableWrite(false);
+    }
+
+    public function getString(): string
+    {
+        return $this->string;
     }
 
     public function getStringObject(): \PHPJava\Packages\java\lang\_String
     {
         return $this->stringObject;
     }
+
+    public function setStringObject(\PHPJava\Packages\java\lang\_String $stringObject): self
+    {
+        if ($this->isWritable) {
+            $this->stringObject = $stringObject;
+            $this->freeze();
+        }
+        return $this;
+    }
+
+    public function __toString(): string
+    {
+        return $this->getString();
+    }
 }
diff --git a/src/Packages/java/lang/_String.php b/src/Packages/java/lang/_String.php
@@ -1,6 +1,7 @@
 <?php
 namespace PHPJava\Packages\java\lang;
 
+use PHPJava\Core\JVM\ConstantPool;
 use PHPJava\Exceptions\NotImplementedException;
 use PHPJava\Kernel\Structures\_Utf8;
 use PHPJava\Kernel\Types\_Char;
@@ -322,13 +323,28 @@ public function indexOf($a = null, $b = null)
     /**
      * Returns a canonical representation for the string object.
      *
+     * @native ConstantPool
      * @see https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/package-summary.html#intern
-     * @param null|mixed $a
      * @throws NotImplementedException
      */
-    public function intern($a = null)
-    {
-        throw new NotImplementedException(__METHOD__);
+    public function intern(ConstantPool $cp)
+    {
+        // Find the string from the Constant Pool.
+        foreach ($cp as $key => $value) {
+            if (!($value instanceof _Utf8)) {
+                continue;
+            }
+            /**
+             * @var _Utf8 $value
+             */
+            if ((string) $value === (string) $this->object) {
+                $this->object = $value
+                    ->enableWrite(true)
+                    ->setStringObject($this);
+                break;
+            }
+        }
+        return $this;
     }
 
     /**

diff --git a/tests/Packages/JavaLangStringTest.php b/tests/Packages/JavaLangStringTest.php
@@ -102,6 +102,63 @@ public function testHashCode()
         $this->assertSame('2728214739616339340', $values[2]);
     }
 
+    public function testIntern()
+    {
+        ob_start();
+        $this->initiatedJavaClasses['JavaLangStringTest']
+            ->getInvoker()
+            ->getStatic()
+            ->getMethods()
+            ->call(
+                'intern'
+            );
+        [ $intern, $literal ] = array_filter(explode("\n", ob_get_clean()));
+
+        $this->assertIsNumeric($intern);
+        $this->assertIsNumeric($literal);
+
+        $this->assertSame($intern, $literal);
+    }
+
+    public function testNotInterned()
+    {
+        ob_start();
+        $this->initiatedJavaClasses['JavaLangStringTest']
+            ->getInvoker()
+            ->getStatic()
+            ->getMethods()
+            ->call(
+                'notInterned'
+            );
+        [ $intern, $literal ] = array_filter(explode("\n", ob_get_clean()));
+
+        $this->assertIsNumeric($intern);
+        $this->assertIsNumeric($literal);
+
+        $this->assertNotSame($intern, $literal);
+    }
+
+    public function testNotInternedAfterLiteral()
+    {
+        ob_start();
+        $this->initiatedJavaClasses['JavaLangStringTest']
+            ->getInvoker()
+            ->getStatic()
+            ->getMethods()
+            ->call(
+                'notInternedAfterLiteral'
+            );
+        [ $intern, $literal1, $literal2 ] = array_filter(explode("\n", ob_get_clean()));
+
+        $this->assertIsNumeric($intern);
+        $this->assertIsNumeric($literal1);
+        $this->assertIsNumeric($literal2);
+
+        $this->assertNotSame($intern, $literal1);
+        $this->assertNotSame($intern, $literal2);
+        $this->assertSame($literal1, $literal2);
+    }
+
     public function testReplace()
     {
         ob_start();