package dotty.tools.dotc.core
import language.implicitConversions
object Flags {
/** A FlagSet represents a set of flags. Flags are encoded as follows:
* The first two bits indicate whether a flagset applies to terms,
* to types, or to both. Bits 2..63 are available for properties
* and can be doubly used for terms and types.
* Combining two FlagSets with `|` will give a FlagSet
* that has the intersection of the applicability to terms/types
* of the two flag sets. It is checked that the intersection is not empty.
*/
case class FlagSet(val bits: Long) extends AnyVal {
/** The union of this flag set and the given flag set
*/
def | (that: FlagSet): FlagSet =
if (bits == 0) that
else if (that.bits == 0) this
else {
val tbits = bits & that.bits & KINDFLAGS
assert(tbits != 0, s"illegal flagset combination: $this and $that")
FlagSet(tbits | ((this.bits | that.bits) & ~KINDFLAGS))
}
/** The intersection of this flag set and the given flag set */
def & (that: FlagSet) = FlagSet(bits & that.bits)
/** The intersection of this flag set with the complement of the given flag set */
def &~ (that: FlagSet) = {
val tbits = bits & KINDFLAGS
if ((tbits & that.bits) == 0) this
else FlagSet(tbits | ((this.bits & ~that.bits) & ~KINDFLAGS))
}
/** Does this flag set have a non-empty intersection with the given flag set?
* This means that both the kind flags and the carrier bits have non-empty intersection.
*/
def is(flags: FlagSet): Boolean = {
val fs = bits & flags.bits
(fs & KINDFLAGS) != 0 && (fs & ~KINDFLAGS) != 0
}
/** Does this flag set have a non-empty intersection with the given flag set,
* and at the same time contain none of the flags in the `butNot` set?
*/
def is(flags: FlagSet, butNot: FlagSet): Boolean = is(flags) && !is(butNot)
/** Does this flag set have all of the flags in given flag conjunction?
* Pre: The intersection of the typeflags of both sets must be non-empty.
*/
def is(flags: FlagConjunction): Boolean = {
val fs = bits & flags.bits
(fs & KINDFLAGS) != 0 &&
(fs >>> TYPESHIFT) == (flags.bits >>> TYPESHIFT)
}
/** Does this flag set have all of the flags in given flag conjunction?
* and at the same time contain none of the flags in the `butNot` set?
* Pre: The intersection of the typeflags of both sets must be non-empty.
*/
def is(flags: FlagConjunction, butNot: FlagSet): Boolean = is(flags) && !is(butNot)
def isEmpty = (bits & ~KINDFLAGS) == 0
/** Is this flag set a subset of that one? */
def <= (that: FlagSet) = (bits & that.bits) == bits
/** Does this flag set apply to terms? */
def isTermFlags = (bits & TERMS) != 0
/** Does this flag set apply to terms? */
def isTypeFlags = (bits & TYPES) != 0
/** This flag set with all flags transposed to be type flags */
def toTypeFlags = if (bits == 0) this else FlagSet(bits & ~KINDFLAGS | TYPES)
/** This flag set with all flags transposed to be term flags */
def toTermFlags = if (bits == 0) this else FlagSet(bits & ~KINDFLAGS | TERMS)
/** This flag set with all flags transposed to be common flags */
def toCommonFlags = if (bits == 0) this else FlagSet(bits | KINDFLAGS)
/** The number of non-kind flags in this set */
def numFlags: Int = java.lang.Long.bitCount(bits & ~KINDFLAGS)
/** The lowest non-kind bit set in this flagset */
def firstBit: Int = java.lang.Long.numberOfTrailingZeros(bits & ~KINDFLAGS)
/** The list of non-empty names of flags with given index idx that are set in this FlagSet */
private def flagString(idx: Int): List[String] =
if ((bits & (1L << idx)) == 0) Nil
else {
def halfString(kind: Int) =
if ((bits & (1L << kind)) != 0) flagName(idx)(kind) else ""
val termFS = halfString(TERMindex)
val typeFS = halfString(TYPEindex)
val strs = termFS :: (if (termFS == typeFS) Nil else typeFS :: Nil)
strs filter (_.nonEmpty)
}
/** The list of non-empty names of flags that are set in this FlagSet */
def flagStrings: Seq[String] =
(2 to MaxFlag).flatMap(flagString)
/** The string representation of this flag set */
override def toString = flagStrings.mkString(" ")
}
/** A class representing flag sets that should be tested
* conjunctively. I.e. for a flag conjunction `fc`,
* `x is fc` tests whether `x` contains all flags in `fc`.
*/
case class FlagConjunction(bits: Long) {
override def toString = FlagSet(bits).toString
}
private final val TYPESHIFT = 2
private final val TERMindex = 0
private final val TYPEindex = 1
private final val TERMS = 1 << TERMindex
private final val TYPES = 1 << TYPEindex
private final val KINDFLAGS = TERMS | TYPES
private final val FirstFlag = 2
private final val FirstNotPickledFlag = 48
private final val MaxFlag = 63
private var flagName = Array.fill(64, 2)("")
private def isDefinedAsFlag(idx: Int) = flagName(idx) exists (_.nonEmpty)
/** The flag set containing all defined flags of either kind whose bits
* lie in the given range
*/
private def flagRange(start: Int, end: Int) =
FlagSet((KINDFLAGS.toLong /: (start until end)) ((bits, idx) =>
if (isDefinedAsFlag(idx)) bits | (1L << idx) else bits))
/** The flag with given index between 2 and 63 which applies to terms.
* Installs given name as the name of the flag. */
private def termFlag(index: Int, name: String): FlagSet = {
flagName(index)(TERMindex) = name
FlagSet(TERMS | (1L << index))
}
/** The flag with given index between 2 and 63 which applies to types.
* Installs given name as the name of the flag. */
private def typeFlag(index: Int, name: String): FlagSet = {
flagName(index)(TYPEindex) = name
FlagSet(TYPES | (1L << index))
}
/** The flag with given index between 2 and 63 which applies to both terms and types
* Installs given name as the name of the flag. */
private def commonFlag(index: Int, name: String): FlagSet = {
flagName(index)(TERMindex) = name
flagName(index)(TYPEindex) = name
FlagSet(TERMS | TYPES | (1L << index))
}
/** The union of all flags in given flag set */
def union(flagss: FlagSet*) = (EmptyFlags /: flagss)(_ | _)
/** The conjunction of all flags in given flag set */
def allOf(flagss: FlagSet*) = {
assert(flagss forall (_.numFlags == 1))
FlagConjunction(union(flagss: _*).bits)
}
def commonFlags(flagss: FlagSet*) = union(flagss.map(_.toCommonFlags): _*)
/** The empty flag set */
final val EmptyFlags = FlagSet(0)
// Available flags:
/** Labeled with `private` modifier */
final val Private = commonFlag(2, "private")
/** Labeled with `protected` modifier */
final val Protected = commonFlag(3, "protected")
/** Labeled with `override` modifier */
final val Override = commonFlag(4, "override")
/** A declared, but not defined member */
final val Deferred = commonFlag(5, "<deferred>")
final val DeferredTerm = Deferred.toTermFlags
final val DeferredType = Deferred.toTypeFlags
/** Labeled with `final` modifier */
final val Final = commonFlag(6, "final")
/** A method symbol. */
final val Method = termFlag(7, "<method>")
/** A (term or type) parameter to a class or method */
final val Param = commonFlag(8, "<param>")
final val TermParam = Param.toTermFlags
final val TypeParam = Param.toTypeFlags
/** Labeled with `implicit` modifier (implicit value) */
final val Implicit = termFlag(9, "implicit")
/** A trait */
final val Trait = typeFlag(9, "<trait>")
/** Labeled with `lazy` (a lazy val). */
final val Lazy = termFlag(10, "lazy")
/** A trait that has only abstract methods as members
* (and therefore can be represented by a Java interface
*/
final val Interface = typeFlag(10, "interface")
/** A value or variable accessor (getter or setter) */
final val Accessor = termFlag(11, "<accessor>")
/** Labeled with `sealed` modifier (sealed class) */
final val Sealed = typeFlag(11, "sealed")
final val AccessorOrSealed = Accessor.toCommonFlags
/** A mutable var */
final val Mutable = termFlag(12, "mutable")
/** Class symbol is defined in this/superclass constructor. */
final val InConstructor = typeFlag(12, "<inconstructor>")
/** Symbol is local to current class (i.e. private[this] or protected[this]
* pre: Private or Protected are also set
*/
final val Local = commonFlag(13, "<local>")
/** A field generated for a primary constructor parameter (no matter if it's a 'val' or not),
* or an accessor of such a field.
*/
final val ParamAccessor = commonFlag(14, "<paramaccessor>")
/** A value or class implementing a module */
final val Module = commonFlag(15, "module")
final val ModuleVal = Module.toTermFlags
final val ModuleClass = Module.toTypeFlags
/** A value or class representing a package */
final val Package = commonFlag(16, "<package>")
final val PackageVal = Package.toTermFlags
final val PackageClass = Package.toTypeFlags
/** A case class or its companion object */
final val Case = commonFlag(17, "case")
final val CaseClass = Case.toTypeFlags
final val CaseVal = Case.toTermFlags
/** A compiler-generated symbol, which is visible for type-checking
* (compare with artifact)
*/
final val Synthetic = commonFlag(18, "<synthetic>")
/** Symbol's name is expanded */
final val ExpandedName = commonFlag(19, "<expandedname>")
/** A covariant type variable */
final val CovariantCommon = commonFlag(20, "<covariant>")
final val Covariant = CovariantCommon.toTypeFlags
final val ContravariantCommon = commonFlag(21, "<contravariant>")
final val Contravariant = ContravariantCommon.toTypeFlags
/** Method is a label. */
final val Label = termFlag(22, "<label>")
/** Labeled with `abstract` modifier (an abstract class)
* Note: the flag counts as common, because it can be combined with OVERRIDE in a term.
*/
final val Abstract = commonFlag(23, "abstract")
/** Labeled with of abstract & override */
final val AbsOverride = termFlag(24, "abstract override")
/** Method is assumed to be stable */
final val Stable = termFlag(25, "<stable>")
/** A case parameter (or its accessor, or a GADT skolem) */
final val CaseAccessor = termFlag(26, "<caseaccessor>")
/** A super accessor */
final val SuperAccessor = termFlag(27, "<superaccessor>")
/** A parameter with a default value */
final val DefaultParam = termFlag(28, "<defaultparam>")
/** Symbol is initialized to the default value, e.g. var x: T = _ */
final val DefaultInit = termFlag(29, "<defaultinit>")
/** Symbol is a macro */
final val Macro = commonFlag(30, "<macro>")
/** Symbol is defined by a Java class */
final val JavaDefined = commonFlag(31, "<java>")
/** Symbol is implemented as a Java static */
final val Static = commonFlag(32, "<static>")
/** Variable is accessed from nested function. */
final val Captured = termFlag(33, "<captured>")
/** Symbol should be ignored when typechecking; will be marked ACC_SYNTHETIC in bytecode */
final val Artifact = commonFlag(34, "<artifact>")
/** A bridge method. Set by Erasure */
final val Bridge = termFlag(35, "<bridge>")
/** Symbol is a Java varargs bridge */
final val VBridge = termFlag(36, "<vbridge>")
/** Symbol is a method which should be marked ACC_SYNCHRONIZED */
final val Synchronized = termFlag(37, "<synchronized>")
/** Symbol is a Java-style varargs method */
final val JavaVarargs = termFlag(38, "<varargs>")
// Flags following this one are not pickled
/** Denotation is in train of being loaded and completed, used to catch cyclic dependencies */
final val Touched = commonFlag(48, "<touched>")
/** Class is not allowed to accept new members because fingerprint of subclass has been taken */
final val Frozen = commonFlag(49, "<frozen>")
/** An error symbol */
final val Erroneous = commonFlag(50, "<is-error>")
/** Class has been lifted out to package level, local value has been lifted out to class level */
final val Lifted = commonFlag(51, "<lifted>")
/** Term member has been mixed in */
final val MixedIn = commonFlag(52, "<mixedin>")
/** Symbol is a generated specialized member */
final val Specialized = commonFlag(53, "<specialized>")
/** Symbol is an implementation class */
final val ImplClass = typeFlag(54, "<implclass>")
/** An existentially bound symbol (Scala 2.x only) */
final val Scala2ExistentialCommon = commonFlag(55, "<existential>")
final val Scala2Existential = Scala2ExistentialCommon.toTypeFlags
/** An overloaded symbol (Scala 2.x only) */
final val Scala2Overloaded = termFlag(56, "<overloaded>")
/** A module variable (Scala 2.x only) */
final val Scala2ModuleVar = termFlag(57, "<modulevar>")
/** A definition that's initialized before the super call (Scala 2.x only) */
final val Scala2PreSuper = termFlag(58, "<presuper>")
// --------- Combined Flag Sets and Conjunctions ----------------------
/** Flags representing source modifiers */
final val ModifierFlags =
commonFlags(Private, Protected, Abstract, Final,
Sealed, Case, Implicit, Override, AbsOverride, Lazy)
/** Flags representing access rights */
final val AccessFlags = Private | Protected | Local
/** Flags guaranteed to be set upon symbol creation */
final val FromStartFlags =
AccessFlags | Module | Package | Deferred | Param | Scala2ExistentialCommon | Touched |
Static | CovariantCommon | ContravariantCommon | ExpandedName | AccessorOrSealed | Frozen |
Erroneous
assert(FromStartFlags.isTermFlags && FromStartFlags.isTypeFlags)
// TODO: Should check that FromStartFlags do not changed in completion
/** A value that's unstable unless complemented with a Stable flag */
final val UnstableValue = Mutable | Method
/** Flags that express the variance of a type parameter. */
final val VarianceFlags = Covariant | Contravariant
/** Flags that are passed from a type parameter of a class to a refinement symbol
* that sets the type parameter */
final val RetainedTypeArgFlags = VarianceFlags | Protected | Local
/** Modules always have these flags set */
final val ModuleCreationFlags = ModuleVal
/** Module classes always have these flags set */
final val ModuleClassCreationFlags = ModuleClass | Final
/** The flags of the self symbol */
final val SelfSymFlags = Private | Local | Deferred
/** The flags of a type parameter */
final val TypeParamCreationFlags = TypeParam | Protected | Local
/** Flags that can apply to both a module val and a module class, except those that
* are added at creation anyway
*/
final val RetainedModuleValAndClassFlags: FlagSet =
AccessFlags | Package | Case |
Synthetic | ExpandedName | JavaDefined | Static | Artifact |
Erroneous | Lifted | MixedIn | Specialized
/** Flags that can apply to a module val */
final val RetainedModuleValFlags: FlagSet = RetainedModuleValAndClassFlags |
Override | Final | Method | Implicit | Lazy |
Accessor | AbsOverride | Stable | Captured | Synchronized
/** Flags that can apply to a module class */
final val RetainedModuleClassFlags: FlagSet = RetainedModuleValAndClassFlags |
InConstructor | ImplClass
/** Packages and package classes always have these flags set */
final val PackageCreationFlags =
Module | Package | Final | JavaDefined | Static
/** These flags are pickled */
final val PickledFlags = flagRange(FirstFlag, FirstNotPickledFlag)
/** An abstract class or a trait */
final val AbstractOrTrait = Abstract | Trait
/** Labeled `private` or `protected[local]` */
final val PrivateOrLocal = Private | Local
/** A type parameter with synthesized name */
final val ExpandedTypeParam = allOf(ExpandedName, TypeParam)
/** A parameter or parameter accessor */
final val ParamOrAccessor = Param | Accessor
/** A Java interface */
final val JavaInterface = allOf(JavaDefined, Trait)
/** Labeled private[this] */
final val PrivateLocal = allOf(Private, Local)
/** A private parameter accessor */
final val PrivateLocalParamAccessor = allOf(Private, Local, ParamAccessor)
/** A local parameter */
final val ParamAndLocal = allOf(Param, Local)
/** Labeled protected[this] */
final val ProtectedLocal = allOf(Protected, Local)
/** Java symbol which is `protected` and `static` */
final val StaticProtected = allOf(JavaDefined, Protected, Static)
final val AbstractFinal = allOf(Abstract, Final)
final val AbstractSealed = allOf(Abstract, Sealed)
final val SyntheticArtifact = allOf(Synthetic, Artifact)
final val SyntheticTermParam = allOf(Synthetic, TermParam)
final val SyntheticTypeParam = allOf(Synthetic, TypeParam)
final val SyntheticCase = allOf(Synthetic, Case)
final val AbstractAndOverride = allOf(Abstract, Override)
implicit def conjToFlagSet(conj: FlagConjunction): FlagSet =
FlagSet(conj.bits)
}
