package dotty.tools
package dotc
package core
import Decorators._
import Periods._
import Names._
import Phases._
import Types._
import Symbols._
import Scopes._
import TypeComparers._, NameOps._, SymDenotations._, util.Positions._
import ast.Trees._, ast.untpd
import util.FreshNameCreator
import typer._
import config.Settings._
import reporting._
import collection.mutable
import collection.immutable.BitSet
import printing._
import config.{Settings, ScalaSettings, Platform, JavaPlatform}
import language.implicitConversions
object Contexts {
/** A context is passed basically everywhere in dotc.
* This is convenient but carries the risk of captured contexts in
* objects that turn into space leaks. To combat this risk, here are some
* conventions to follow:
*
* - Never let an implicit context be an argument of a class whose instances
* live longer than the context.
* - Classes that need contexts for their initialization take an explicit parameter
* named `initctx`. They pass initctx to all positions where it is needed
* (and these positions should all be part of the intialization sequence of the class).
* - Classes that need contexts that survive initialization are instead passed
* a "condensed context", typically named `cctx` (or they create one). Consensed contexts
* just add some basic information to the context base without the
* risk of capturing complete trees.
* - To make sure these rules are kept, it would be good to do a sanity
* check using bytecode inspection with javap or scalap: Keep track
* of all class fields of type context; allow them only in whitelisted
* classes (which should be short-lived).
*/
abstract class Context extends Periods
with Substituters
with TypeOps
with Phases
with Printers
with Symbols
with SymDenotations
with Reporting
with NamerContextOps
with Cloneable { thiscontext =>
implicit def ctx: Context = this
/** The context base at the root */
val base: ContextBase
/** All outer contexts, ending in `base.initialCtx` and then `NoContext` */
def outersIterator = new Iterator[Context] {
var current = thiscontext
def hasNext = current != NoContext
def next = { val c = current; current = current.outer; c }
}
/** The outer context */
private[this] var _outer: Context = _
protected def outer_=(outer: Context) = _outer = outer
def outer: Context = _outer
/** The current context */
private[this] var _period: Period = _
protected def period_=(period: Period) = _period = period
def period: Period = _period
/** The current set of type constraints */
private[this] var _constraints: Constraints = _
protected def constraints_=(constraints: Constraints) = _constraints = constraints
def constraints: Constraints = _constraints
/** The scope nesting level */
private[this] var _scopeNestingLevel: Int = 0
def scopeNestingLevel: Int = {
if (this._scopeNestingLevel == outer.scopeNestingLevel && this.scope != outer.scope)
this._scopeNestingLevel = outer.scopeNestingLevel + 1
this._scopeNestingLevel
}
/** The current type comparer */
private[this] var _typeComparer: TypeComparer = _
protected def typeComparer_=(typeComparer: TypeComparer) = _typeComparer = typeComparer
def typeComparer: TypeComparer = {
if ((_typeComparer == null) ||
(_typeComparer eq outer.typeComparer) && (constraints ne outer.constraints))
_typeComparer = new TypeComparer()
_typeComparer
}
/** The current position */
private[this] var _position: Position = _
protected def position_=(position: Position) = _position = position
def position: Position = _position
/** The current plain printer */
private[this] var _plainPrinter: Context => Printer = _
protected def plainPrinter_=(plainPrinter: Context => Printer) = _plainPrinter = plainPrinter
def plainPrinter: Context => Printer = _plainPrinter
/** The current refined printer */
private[this] var _refinedPrinter: Context => Printer = _
protected def refinedPrinter_=(refinedPrinter: Context => Printer) = _refinedPrinter = refinedPrinter
def refinedPrinter: Context => Printer = _refinedPrinter
/** The current owner symbol */
private[this] var _owner: Symbol = _
protected def owner_=(owner: Symbol) = _owner = owner
def owner: Symbol = _owner
/** The current settings values */
private[this] var _sstate: SettingsState = _
protected def sstate_=(sstate: SettingsState) = _sstate = sstate
def sstate: SettingsState = _sstate
/** The current tree */
private[this] var _tree: Tree[_ >: Untyped] = _
protected def tree_=(tree: Tree[_ >: Untyped]) = _tree = tree
def tree: Tree[_ >: Untyped] = _tree
/** The current scope */
private[this] var _scope: Scope = _
protected def scope_=(scope: Scope) = _scope = scope
def scope: Scope = _scope
/** The currently visible imports */
private[this] var _imports: List[ImportInfo] = _
protected def imports_=(imports: List[ImportInfo]) = _imports = imports
def imports: List[ImportInfo] = _imports
/** The current reporter */
private[this] var _reporter: Reporter = _
protected def reporter_=(reporter: Reporter) = _reporter = reporter
def reporter: Reporter = _reporter
/** An optional diagostics buffer than is used by some checking code
* to provide more information in the buffer if it exists.
*/
private var _diagnostics: Option[StringBuilder] = _
protected def diagnostics_=(diagnostics: Option[StringBuilder]) = _diagnostics = diagnostics
def diagnostics: Option[StringBuilder] = _diagnostics
/** A map in which more contextual properties can be stored */
private var _moreProperties: Map[String, Any] = _
protected def moreProperties_=(moreProperties: Map[String, Any]) = _moreProperties = moreProperties
def moreProperties: Map[String, Any] = _moreProperties
/** If -Ydebug is on, the top of the stack trace where this context
* was created, otherwise `null`.
*/
private var creationTrace: Array[StackTraceElement] = _
setCreationTrace()
private def setCreationTrace() =
if (true || this.settings.debug.value)
creationTrace = (new Throwable).getStackTrace().take(20)
/** Print all enclosing context's creation stacktraces */
def printCreationTraces() = {
println("=== context creation trace =======")
for (ctx <- outersIterator) {
println(s">>>>>>>>> $ctx")
if (ctx.creationTrace != null) println(ctx.creationTrace.mkString("\n"))
}
println("=== end context creation trace ===")
}
/** Leave message in diagnostics buffer if it exists */
def diagnose(str: => String) =
for (sb <- diagnostics) {
sb.setLength(0)
sb.append(str)
}
/** The next outer context whose tree is a template or package definition */
def enclTemplate: Context = {
var c = this
while (c != NoContext && !c.tree.isInstanceOf[Template[_]] && !c.tree.isInstanceOf[PackageDef[_]])
c = c.outer
c
}
/** The current source file; will be derived from current
* compilation unit.
*/
def source = util.NoSource // for now
/** Does current phase use an erased types interpretation? */
def erasedTypes: Boolean = phase.erasedTypes
/** Is the debug option set? */
def debug: Boolean = base.settings.debug.value
/** Is the verbose option set? */
def verbose: Boolean = base.settings.verbose.value
/** A condensed context containing essential information of this but
* no outer contexts except the initial context.
*/
private var _condensed: CondensedContext = null
def condensed: CondensedContext = {
if (_condensed eq outer.condensed)
_condensed = base.initialCtx.fresh
.withPeriod(period)
// constraints is not preserved in condensed
.withPlainPrinter(plainPrinter)
.withRefinedPrinter(refinedPrinter)
.withOwner(owner)
.withSettings(sstate)
// tree is not preserved in condensed
.withReporter(reporter)
.withDiagnostics(diagnostics)
.withMoreProperties(moreProperties)
_condensed
}
/** A fresh clone of this context. */
def fresh: FreshContext = {
val newctx = super.clone.asInstanceOf[FreshContext]
newctx.outer = this
newctx.setCreationTrace()
newctx
}
}
/** A condensed context provides only a small memory footprint over
* a Context base, and therefore can be stored without problems in
* long-lived objects.
*/
abstract class CondensedContext extends Context {
override def condensed = this
}
/** A fresh context allows selective modification
* of its attributes using the with... methods.
*/
abstract class FreshContext extends CondensedContext {
def withPeriod(period: Period): this.type = { this.period = period; this }
def withConstraints(constraints: Constraints): this.type = { this.constraints = constraints; this }
def withPosition(position: Position): this.type = { this.position = position; this }
def withPlainPrinter(printer: Context => Printer): this.type = { this.plainPrinter = printer; this }
def withRefinedPrinter(printer: Context => Printer): this.type = { this.refinedPrinter = printer; this }
def withOwner(owner: Symbol): this.type = { this.owner = owner; this }
def withNewScope: this.type = { this.scope = newScope; this }
def withSettings(sstate: SettingsState): this.type = { this.sstate = sstate; this }
def withTree(tree: Tree[_ >: Untyped]): this.type = { this.tree = tree; this }
def withScope(scope: Scope): this.type = { this.scope = scope; this }
def withImport(importInfo: ImportInfo): this.type = { this.imports = importInfo :: imports; this }
def withReporter(reporter: Reporter): this.type = { this.reporter = reporter; this }
def withDiagnostics(diagnostics: Option[StringBuilder]): this.type = { this.diagnostics = diagnostics; this }
def withMoreProperties(moreProperties: Map[String, Any]): this.type = { this.moreProperties = moreProperties; this }
def withProperty(prop: (String, Any)): this.type = withMoreProperties(moreProperties + prop)
def withPhase(pid: PhaseId): this.type = withPeriod(Period(runId, pid))
def withSetting[T](setting: Setting[T], value: T): this.type =
withSettings(setting.updateIn(sstate, value))
def withDebug = withSetting(base.settings.debug, true)
}
/** A class defining the initial context with given context base
* and set of possible settings.
*/
private class InitialContext(val base: ContextBase, settings: SettingGroup) extends FreshContext {
outer = NoContext
period = InitialPeriod
constraints = Map()
position = NoPosition
plainPrinter = new PlainPrinter(_)
refinedPrinter = new RefinedPrinter(_)
owner = NoSymbol
sstate = settings.defaultState
tree = untpd.EmptyTree
reporter = new ConsoleReporter()(this)
diagnostics = None
moreProperties = Map.empty
}
object NoContext extends Context {
override def typeComparer = null
lazy val base = unsupported("base")
}
/** A context base defines state and associated methods that exist once per
* compiler run.
*/
class ContextBase extends ContextState
with Transformers.TransformerBase
with Denotations.DenotationsBase
with Phases.PhasesBase {
/** The applicable settings */
val settings = new ScalaSettings
/** The initial context */
val initialCtx: Context = new InitialContext(this, settings)
/** The symbol loaders */
val loaders = new SymbolLoaders
/** The platform */
val platform: Platform = new JavaPlatform
/** The standard fresh name creator */
val freshNames = new FreshNameCreator.Default
def freshName(prefix: String = ""): String = freshNames.newName(prefix)
def freshName(prefix: Name): String = freshName(prefix.toString)
/** The loader that loads the members of _root_ */
def rootLoader(root: TermSymbol)(implicit ctx: Context): SymbolLoader = platform.rootLoader(root)
NoPhase // initialize some phases
SomePhase // TODO: Is there a cleaner way to do this?
/** The standard definitions */
val definitions = new Definitions()(initialCtx)
}
/** The essential mutable state of a context base, collected into a common class */
class ContextState {
// Symbols state
/** A counter for unique ids */
private[core] var _nextId = 0
def nextId = { _nextId += 1; _nextId }
/** A map from a superclass id to the typeref of the class that has it */
private[core] var classOfId = new Array[TypeRef](InitialSuperIdsSize)
/** A map from a the typeref of a class to its superclass id */
private[core] val superIdOfClass = new mutable.HashMap[TypeRef, Int]
/** The last allocated superclass id */
private[core] var lastSuperId = -1
/** Allocate and return next free superclass id */
private[core] def nextSuperId: Int = {
lastSuperId += 1;
if (lastSuperId >= classOfId.length) {
val tmp = new Array[TypeRef](classOfId.length * 2)
classOfId.copyToArray(tmp)
classOfId = tmp
}
lastSuperId
}
// SymDenotations state
/** A table where unique superclass bits are kept.
* These are bitsets that contain the superclass ids of all base classes of a class.
* Used to speed up isSubClass tests.
*/
private[core] val uniqueBits = new util.HashSet[BitSet]("superbits", 1024)
// Types state
/** A table for hash consing unique types */
private[core] val uniques = new util.HashSet[Type]("uniques", initialUniquesCapacity) {
override def hash(x: Type): Int = x.hash
}
/** The number of recursive invocation of underlying on a NamedType
* during a controlled operation.
*/
private[core] var underlyingRecursions: Int = 0
/** The set of named types on which a currently active invocation
* of underlying during a controlled operation exists. */
private[core] val pendingUnderlying = new mutable.HashSet[Type]
// Phases state
/** Phases by id */
private[core] var phases = new Array[Phase](MaxPossiblePhaseId + 1)
/** The number of defined phases. This includes NoPhase, so nphases >= 1 */
private[core] var nphases = 0
// Printers state
/** Number of recursive invocations of a show method on cuyrrent stack */
private[dotc] var toTextRecursions = 0
// Reporters state
private[dotc] var indent = 0
protected[dotc] val indentTab = " "
}
object Context {
/** Implicit conversion that injects all printer operations into a context */
implicit def toPrinter(ctx: Context) = ctx.printer
/** implicit conversion that injects all ContextBase members into a context */
implicit def toBase(ctx: Context): ContextBase = ctx.base
val theBase = new ContextBase // !!! DEBUG, so that we can use a minimal context for reporting even in code that normallly cannot access a context
}
/** Initial size of superId table */
private final val InitialSuperIdsSize = 4096
/** Initial capacity of uniques HashMap */
private[core] final val initialUniquesCapacity = 50000
/** How many recursive calls to NamedType#underlying are performed before
* logging starts.
*/
private[core] final val LogPendingUnderlyingThreshold = 50
/** How many recursive calls to isSubType are performed before
* logging starts.
*/
private[core] final val LogPendingSubTypesThreshold = 50
}
