scala.tools.nsc.typechecker

# Contexts

#### trait Contexts extends AnyRef

Self Type
  Analyzer
Source
  Contexts.scala
Version

  1.0

Linear Supertypes
AnyRef, Any
Known Subclasses
Analyzer, Duplicator, Duplicators, Erasure, SpecializationDuplicator, TreeCheckers, erasure, treeChecker
Type Hierarchy Learn more about scaladoc diagrams
Ordering

1. Alphabetic
2. By inheritance

Inherited

1. Contexts
2. AnyRef
3. Any

Implicitly

1. by any2stringadd
2. by StringFormat
3. by Ensuring
4. by ArrowAssoc

1. Hide All
2. Show all

Learn more about member selection
Visibility

1. Public
2. All

### Type Members

1. #### class Context extends AnyRef

   A motley collection of the state and loosely associated behaviour of the type checker.

   A motley collection of the state and loosely associated behaviour of the type checker. Each `Typer` has an associated context, and as it descends into the tree new `(Typer, Context)` pairs are spawned.

   Meet the crew; first the state:

   - A tree, symbol, and scope representing the focus of the typechecker
   - An enclosing context, `outer`.
   - The current compilation unit.
   - A variety of bits that track the current error reporting policy (more on this later); whether or not implicits/macros are enabled, whether we are in a self or super call or in a constructor suffix. These are represented as bits in the mask `contextMode`.
   - Some odds and ends: undetermined type pararameters of the current line of type inference; contextual augmentation for error messages, tracking of the nesting depth.

   And behaviour:

   - The central point for issuing errors and warnings from the typechecker, with a means to buffer these for use in 'silent' type checking, when some recovery might be possible.
   - `Context` is something of a Zipper for the tree were are typechecking: it `enclosingContextChain` is the path back to the root. This is exactly what we need to resolve names (`lookupSymbol`) and to collect in-scope implicit defintions (`implicitss`) Supporting these are `imports`, which represents all `Import` trees in in the enclosing context chain.
   - In a similar vein, we can assess accessiblity (`isAccessible`.)

   More on error buffering: When are type errors recoverable? In quite a few places, it turns out. Some examples: trying to type an application with/without the expected type, or with/without implicit views enabled. This is usually mediated by `Typer.silent`, `Inferencer#tryTwice`.

   Intially, starting from the `typer` phase, the contexts either buffer or report errors; afterwards errors are thrown. This is configured in `rootContext`. Additionally, more fine grained control is needed based on the kind of error; ambiguity errors are often suppressed during exploraratory typing, such as determining whether `a == b` in an argument position is an assignment or a named argument, when `Infererencer#isApplicableSafe` type checks applications with and without an expected type, or whtn `Typer#tryTypedApply` tries to fit arguments to a function type with/without implicit views.

   When the error policies entails error/warning buffering, the mutable ReportBuffer records everything that is issued. It is important to note, that child Contexts created with `make` "inherit" the very same `ReportBuffer` instance, whereas children spawned through `makeSilent` receive an separate, fresh buffer.

2. #### abstract class ContextReporter extends Reporter

   A reporter for use during type checking.

   A reporter for use during type checking. It has multiple modes for handling errors.

   The default (immediate mode) is to send the error to the global reporter. When switched into buffering mode via makeBuffering, errors and warnings are buffered and not be reported (there's a special case for ambiguity errors for some reason: those are force to the reporter when context.ambiguousErrors, or else they are buffered -- TODO: can we simplify this?)

   When using the type checker after typers, an error results in a TypeError being thrown. TODO: get rid of this mode.

   To handle nested contexts, reporters share buffers. TODO: only buffer in BufferingReporter, emit immediately in ImmediateReporter

3. #### trait ImportContext extends Analyzer.Context

   A `Context` focussed on an `Import` tree

4. #### class ImportInfo extends AnyRef

5. #### type ImportType = Global.ImportType

### Value Members

1. #### final def !=(arg0: Any): Boolean

   Definition Classes
     AnyRef → Any

2. #### final def ##(): Int

   Definition Classes
     AnyRef → Any

3. #### def +(other: String): String

   Implicit information
     This member is added by an implicit conversion from Contexts to any2stringadd[Contexts] performed by method any2stringadd in scala.Predef.
   Definition Classes
     any2stringadd

4. #### def ->[B](y: B): (Contexts, B)

   Implicit information
     This member is added by an implicit conversion from Contexts to ArrowAssoc[Contexts] performed by method ArrowAssoc in scala.Predef.
   Definition Classes
     ArrowAssoc
   Annotations
     @inline()

5. #### final def ==(arg0: Any): Boolean

   Definition Classes
     AnyRef → Any

6. #### val ImportType: Global.ImportType.type

7. #### object NoContext extends Analyzer.Context

8. #### def ambiguousDefnAndImport(owner: Global.Symbol, imp: Analyzer.ImportInfo): Global.LookupAmbiguous

9. #### def ambiguousImports(imp1: Analyzer.ImportInfo, imp2: Analyzer.ImportInfo): Global.LookupAmbiguous

10. #### final def asInstanceOf[T0]: T0

    Definition Classes
      Any

11. #### def clone(): AnyRef

    Attributes
      protected[java.lang]
    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

12. #### def ensuring(cond: (Contexts) ⇒ Boolean, msg: ⇒ Any): Contexts

    Implicit information
      This member is added by an implicit conversion from Contexts to Ensuring[Contexts] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

13. #### def ensuring(cond: (Contexts) ⇒ Boolean): Contexts

    Implicit information
      This member is added by an implicit conversion from Contexts to Ensuring[Contexts] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

14. #### def ensuring(cond: Boolean, msg: ⇒ Any): Contexts

    Implicit information
      This member is added by an implicit conversion from Contexts to Ensuring[Contexts] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

15. #### def ensuring(cond: Boolean): Contexts

    Implicit information
      This member is added by an implicit conversion from Contexts to Ensuring[Contexts] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

16. #### final def eq(arg0: AnyRef): Boolean

    Definition Classes
      AnyRef

17. #### def equals(arg0: Any): Boolean

    Definition Classes
      AnyRef → Any

18. #### def finalize(): Unit

    Attributes
      protected[java.lang]
    Definition Classes
      AnyRef
    Annotations
      @throws( classOf[java.lang.Throwable] )

19. #### def formatted(fmtstr: String): String

    Implicit information
      This member is added by an implicit conversion from Contexts to StringFormat[Contexts] performed by method StringFormat in scala.Predef.
    Definition Classes
      StringFormat
    Annotations
      @inline()

20. #### final def getClass(): Class[_]

    Definition Classes
      AnyRef → Any

21. #### def hashCode(): Int

    Definition Classes
      AnyRef → Any

22. #### final def isInstanceOf[T0]: Boolean

    Definition Classes
      Any

23. #### var lastAccessCheckDetails: String

24. #### final def ne(arg0: AnyRef): Boolean

    Definition Classes
      AnyRef

25. #### final def notify(): Unit

    Definition Classes
      AnyRef

26. #### final def notifyAll(): Unit

    Definition Classes
      AnyRef

27. #### def onTreeCheckerError(pos: Global.Position, msg: String): Unit

    Attributes
      protected

28. #### def resetContexts(): Unit

29. #### def rootContext(unit: Global.CompilationUnit, tree: Global.Tree = EmptyTree, throwing: Boolean = false, checking: Boolean = false): Analyzer.Context

30. #### def rootContextPostTyper(unit: Global.CompilationUnit, tree: Global.Tree = EmptyTree): Analyzer.Context

31. #### def rootImports(unit: Global.CompilationUnit): List[Global.Symbol]

    List of symbols to import from in a root context.

    List of symbols to import from in a root context. Typically that is `java.lang`, `scala`, and scala.Predef, in that order. Exceptions:

    - if option `-Yno-imports` is given, nothing is imported
    - if the unit is java defined, only `java.lang` is imported
    - if option `-Yno-predef` is given, if the unit body has an import of Predef among its leading imports, or if the tree is scala.Predef, `Predef` is not imported.
    Attributes
      protected

32. #### final def synchronized[T0](arg0: ⇒ T0): T0

    Definition Classes
      AnyRef

33. #### def toString(): String

    Definition Classes
      AnyRef → Any

34. #### final def wait(): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

35. #### final def wait(arg0: Long, arg1: Int): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

36. #### final def wait(arg0: Long): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

37. #### def warnUnusedImports(unit: Global.CompilationUnit): Unit

38. #### def →[B](y: B): (Contexts, B)

    Implicit information
      This member is added by an implicit conversion from Contexts to ArrowAssoc[Contexts] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
      ArrowAssoc

### Inherited from AnyRef

### Inherited from Any

### Inherited by implicit conversion any2stringadd from Contexts to any2stringadd[Contexts]

### Inherited by implicit conversion StringFormat from Contexts to StringFormat[Contexts]

### Inherited by implicit conversion Ensuring from Contexts to Ensuring[Contexts]

### Inherited by implicit conversion ArrowAssoc from Contexts to ArrowAssoc[Contexts]

### Ungrouped