Value class to represent jvm flags.

That clenching you feel in your gut when you watch the
Ints hurtling in all directions is your signal that a little
type safety is good for the soul. With this value class it
is now somewhat harder to confuse java bits with scala bits,
although not nearly hard enough.

1 files changed, 86 insertions, 0 deletions

diff --git a/src/reflect/scala/reflect/internal/JavaAccFlags.scala b/src/reflect/scala/reflect/internal/JavaAccFlags.scala
new file mode 100644
index 0000000000..838a44dbf1
--- /dev/null
+++ b/src/reflect/scala/reflect/internal/JavaAccFlags.scala
@@ -0,0 +1,86 @@
+/* NSC -- new Scala compiler
+ * Copyright 2005-2013 LAMP/EPFL
+ * @author  Paul Phillips
+ */
+
+package scala.reflect
+package internal
+
+import java.lang.{ Class => jClass }
+import java.lang.reflect.{
+  Member => jMember, Constructor => jConstructor, Field => jField, Method => jMethod,
+  AnnotatedElement => jAnnotatedElement
+}
+import java.lang.reflect.Modifier
+import JavaAccFlags._
+import ClassfileConstants._
+
+/** A value class which encodes the access_flags (JVMS 4.1)
+ *  for a field, method, or class. The low 16 bits are the same
+ *  as those returned by java.lang.reflect.Member#getModifiers.
+ *  The high bits encode whether the access flags are associated
+ *  with a class, constructor, field, interface, or method.
+ */
+final class JavaAccFlags private (val coded: Int) extends AnyVal {
+  private def has(mask: Int) = (flags & mask) != 0
+  private def flagCarrierId  = coded >>> 16
+  private def flags          = coded & 0xFFFF
+
+  def isAbstract     = has(JAVA_ACC_ABSTRACT)
+  def isAnnotation   = has(JAVA_ACC_ANNOTATION)
+  def isBridge       = has(JAVA_ACC_BRIDGE)
+  def isEnum         = has(JAVA_ACC_ENUM)
+  def isFinal        = has(JAVA_ACC_FINAL)
+  def isInterface    = has(JAVA_ACC_INTERFACE)
+  def isNative       = has(JAVA_ACC_NATIVE)
+  def isPrivate      = has(JAVA_ACC_PRIVATE)
+  def isProtected    = has(JAVA_ACC_PROTECTED)
+  def isPublic       = has(JAVA_ACC_PUBLIC)
+  def isStatic       = has(JAVA_ACC_STATIC)
+  def isStrictFp     = has(JAVA_ACC_STRICT)
+  def isSuper        = has(JAVA_ACC_SUPER)
+  def isSynchronized = has(JAVA_ACC_SYNCHRONIZED)
+  def isSynthetic    = has(JAVA_ACC_SYNTHETIC)
+  def isTransient    = has(JAVA_ACC_TRANSIENT)
+  def isVarargs      = has(JAVA_ACC_VARARGS)
+  def isVolatile     = has(JAVA_ACC_VOLATILE)
+
+  /** Do these flags describe a member which has either protected or package access?
+   *  Such access in java is encoded in scala as protected[foo] or private[foo], where
+   *  `foo` is the defining package.
+   */
+  def hasPackageAccessBoundary = !has(JAVA_ACC_PRIVATE | JAVA_ACC_PUBLIC) // equivalently, allows protected or package level access
+  def isPackageProtected       = !has(JAVA_ACC_PRIVATE | JAVA_ACC_PROTECTED | JAVA_ACC_PUBLIC)
+
+  def toJavaFlags: Int = flags
+  def toScalaFlags: Long = flagCarrierId match {
+    case Method | Constructor => FlagTranslation methodFlags flags
+    case Class                => FlagTranslation classFlags flags
+    case _                    => FlagTranslation fieldFlags flags
+  }
+}
+
+object JavaAccFlags {
+  private val Unknown     = 0
+  private val Class       = 1
+  private val Field       = 2
+  private val Method      = 3
+  private val Constructor = 4
+
+  private def create(flagCarrier: Int, access_flags: Int): JavaAccFlags =
+    new JavaAccFlags((flagCarrier << 16) | (access_flags & 0xFFFF))
+
+  def classFlags(flags: Int): JavaAccFlags       = create(Class, flags)
+  def methodFlags(flags: Int): JavaAccFlags      = create(Method, flags)
+  def fieldFlags(flags: Int): JavaAccFlags       = create(Field, flags)
+  def constructorFlags(flags: Int): JavaAccFlags = create(Constructor, flags)
+
+  def apply(access_flags: Int): JavaAccFlags = create(Unknown, access_flags)
+  def apply(clazz: jClass[_]): JavaAccFlags  = classFlags(clazz.getModifiers)
+  def apply(member: jMember): JavaAccFlags   = member match {
+    case x: jConstructor[_] => constructorFlags(x.getModifiers)
+    case x: jMethod         => methodFlags(x.getModifiers)
+    case x: jField          => fieldFlags(x.getModifiers)
+    case _                  => apply(member.getModifiers)
+  }
+}