package dotty.tools package dotc package core import Decorators._ import Periods._ import Names._ import Phases._ import Types._ import Symbols._ import Scopes._ import NameOps._ import Uniques._ import SymDenotations._ import util.Positions._ import ast.Trees._ import ast.untpd import util.{FreshNameCreator, SimpleMap, SourceFile, NoSource} import typer._ import Implicits.ContextualImplicits 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 scope nesting level */ private[this] var _mode: Mode = _ protected def mode_=(mode: Mode) = _mode = mode def mode: Mode = _mode /** The current type comparer */ private[this] var _typerState: TyperState = _ protected def typerState_=(typerState: TyperState) = _typerState = typerState def typerState: TyperState = _typerState /** The current plain printer */ private[this] var _printerFn: Context => Printer = _ protected def printerFn_=(printerFn: Context => Printer) = _printerFn = printerFn def printerFn: Context => Printer = _printerFn /** 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 _compilationUnit: CompilationUnit = _ protected def compilationUnit_=(compilationUnit: CompilationUnit) = _compilationUnit = compilationUnit def compilationUnit: CompilationUnit = _compilationUnit /** 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 current typer */ private[this] var _typer: Typer = _ protected def typer_=(typer: Typer) = _typer = typer def typer: Typer = _typer /** The currently active import info */ private[this] var _importInfo: ImportInfo = _ protected def importInfo_=(importInfo: ImportInfo) = _importInfo = importInfo def importInfo: ImportInfo = _importInfo /** The current compiler-run specific Info */ private[this] var _runInfo: RunInfo = _ protected def runInfo_=(runInfo: RunInfo) = _runInfo = runInfo def runInfo: RunInfo = _runInfo /** 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 private var _typeComparer: TypeComparer = _ protected def typeComparer_=(typeComparer: TypeComparer) = _typeComparer = typeComparer def typeComparer: TypeComparer = { if (_typeComparer.ctx ne this) _typeComparer = _typeComparer.copyIn(this) _typeComparer } /** The new implicit references that are introduced by this scope */ private var implicitsCache: ContextualImplicits = null def implicits: ContextualImplicits = { if (implicitsCache == null ) implicitsCache = { val implicitRefs: List[TermRef] = if (isClassDefContext) owner.thisType.implicitMembers else if (isImportContext) importInfo.importedImplicits else if (isNonEmptyScopeContext) scope.implicitDecls else Nil if (implicitRefs.isEmpty) outer.implicits else new ContextualImplicits(implicitRefs, outer.implicits.ctx)(this) } implicitsCache } /** The history of implicit searches that are currently active */ private var _searchHistory: SearchHistory = null protected def searchHistory_= (searchHistory: SearchHistory) = _searchHistory = searchHistory def searchHistory: SearchHistory = _searchHistory /** If -Ydebug is on, the top of the stack trace where this context * was created, otherwise `null`. */ private var creationTrace: Array[StackTraceElement] = _ private def setCreationTrace() = if (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 ===") } /** The current reporter */ def reporter: Reporter = typerState.reporter /** Is this a context for the members of a class definition? */ def isClassDefContext: Boolean = owner.isClass && (owner ne outer.owner) /** Is this a context that introduces an import clause? */ def isImportContext: Boolean = (this ne NoContext) && (this.importInfo ne outer.importInfo) /** Is this a context that introduces a non-empty scope? */ def isNonEmptyScopeContext: Boolean = (this.scope ne outer.scope) && this.scope.nonEmpty /** 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: SourceFile = if (compilationUnit == null) NoSource else compilationUnit.source /** 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) .withNewMode(mode) // typerState and its constraint is not preserved in condensed // reporter is always ThrowingReporter .withPrinterFn(printerFn) .withOwner(owner) .withSettings(sstate) // tree is not preserved in condensed .withRunInfo(runInfo) .withDiagnostics(diagnostics) .withMoreProperties(moreProperties) _condensed } /** A fresh clone of this context. */ def fresh: FreshContext = { val newctx: Context = super.clone.asInstanceOf[FreshContext] newctx.outer = this newctx.implicitsCache = null newctx.setCreationTrace() // Dotty deviation: Scala2x allows access to private members implicitCache and setCreationTrace // even from a subclass prefix. Dotty (and Java) do not. I think that's a bug in Scala2x. newctx.asInstanceOf[FreshContext] } final def withMode(mode: Mode): Context = if (mode != this.mode) fresh.withNewMode(mode) else this final def addMode(mode: Mode): Context = withMode(this.mode | mode) final def maskMode(mode: Mode): Context = withMode(this.mode & mode) final def retractMode(mode: Mode): Context = withMode(this.mode &~ mode) override def toString = "Context(\n" + (outersIterator map ( ctx => s" owner = ${ctx.owner}, scope = ${ctx.scope}") mkString "\n") } /** 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 withNewMode(mode: Mode): this.type = { this.mode = mode; this } def withTyperState(typerState: TyperState): this.type = { this.typerState = typerState; this } def withNewTyperState: this.type = withTyperState(typerState.fresh(isCommittable = true)) def withExploreTyperState: this.type = withTyperState(typerState.fresh(isCommittable = false)) def withPrinterFn(printer: Context => Printer): this.type = { this.printerFn = printer; this } def withOwner(owner: Symbol): this.type = { assert(owner != NoSymbol); this.owner = owner; this } def withSettings(sstate: SettingsState): this.type = { this.sstate = sstate; this } def withCompilationUnit(compilationUnit: CompilationUnit): this.type = { this.compilationUnit = compilationUnit; this } def withTree(tree: Tree[_ >: Untyped]): this.type = { this.tree = tree; this } def withScope(scope: Scope): this.type = { this.scope = scope; this } def withNewScope: this.type = { this.scope = newScope; this } def withTyper(typer: Typer): this.type = { this.typer = typer; this.scope = typer.scope; this } def withImportInfo(importInfo: ImportInfo): this.type = { this.importInfo = importInfo; this } def withRunInfo(runInfo: RunInfo): this.type = { this.runInfo = runInfo; this } def withDiagnostics(diagnostics: Option[StringBuilder]): this.type = { this.diagnostics = diagnostics; this } def withTypeComparerFn(tcfn: Context => TypeComparer): this.type = { this.typeComparer = tcfn(this); this } def withSearchHistory(searchHistory: SearchHistory): this.type = { this.searchHistory = searchHistory; 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 mode = Mode.None typerState = new TyperState(new ThrowingReporter(new ConsoleReporter()(this))) printerFn = new RefinedPrinter(_) owner = NoSymbol sstate = settings.defaultState tree = untpd.EmptyTree runInfo = new RunInfo(this) diagnostics = None moreProperties = Map.empty typeComparer = new TypeComparer(this) searchHistory = new SearchHistory(0, Map()) } object NoContext extends Context { lazy val base = unsupported("base") override def implicits: ContextualImplicits = new ContextualImplicits(Nil, this)(this) } /** 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) // Set up some phases to get started */ usePhases(SomePhase :: Nil) /** 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.AnyRefMap[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 } /** A table for hash consing unique refined types */ private[dotc] val uniqueRefinedTypes = new RefinedUniques /** A table for hash consing unique named types */ private[core] val uniqueNamedTypes = new NamedTypeUniques /** A table for hash consing unique type bounds */ private[core] val uniqueTypeBounds = new TypeBoundsUniques private def uniqueMaps = List(uniques, uniqueRefinedTypes, uniqueNamedTypes, uniqueTypeBounds) /** A map that associates label and size of all uniques sets */ def uniquesSize: Map[String, Int] = uniqueMaps.map(m => m.label -> m.size).toMap /** 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: Array[Phase] = _ // 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 = " " /** Should warnings and errors containing non-sensical strings be suppressed? */ private[dotc] var suppressNonSensicalErrors = true } 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 } /** Info that changes on each compiler run */ class RunInfo(initctx: Context) extends ImplicitRunInfo { implicit val ctx = initctx } /** Initial size of superId table */ private final val InitialSuperIdsSize = 4096 /** Initial capacity of uniques HashMap */ private[core] final val initialUniquesCapacity = 40000 /** 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 }