trait Contexts extends AnyRef
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Type Members
-
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 parameters 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: itenclosingContextChain
is the path back to the root. This is exactly what we need to resolve names (lookupSymbol
) and to collect in-scope implicit definitions (implicitss
) Supporting these areimports
, which represents allImport
trees in in the enclosing context chain. - In a similar vein, we can assess accessibility (
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
.Initially, starting from the
typer
phase, the contexts either buffer or report errors; afterwards errors are thrown. This is configured inrootContext
. Additionally, more fine grained control is needed based on the kind of error; ambiguity errors are often suppressed during exploratory typing, such as determining whethera == b
in an argument position is an assignment or a named argument, whenInferencer#isApplicableSafe
type checks applications with and without an expected type, or whenTyper#tryTypedApply
tries to fit arguments to a function type with/without implicit views.When the error policies entail 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 sameReportBuffer
instance, whereas children spawned throughmakeSilent
receive a separate, fresh buffer. -
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
-
trait
ImportContext
extends Analyzer.Context
A
Context
focussed on anImport
tree - class ImportInfo extends AnyRef
- type ImportType = Global.ImportType
Value Members
-
final
def
!=(arg0: Any): Boolean
Test two objects for inequality.
Test two objects for inequality.
- returns
true
if !(this == that), false otherwise.
- Definition Classes
- AnyRef → Any
-
final
def
##(): Int
Equivalent to
x.hashCode
except for boxed numeric types andnull
.Equivalent to
x.hashCode
except for boxed numeric types andnull
. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. Fornull
returns a hashcode wherenull.hashCode
throws aNullPointerException
.- returns
a hash value consistent with ==
- Definition Classes
- AnyRef → Any
- def +(other: String): String
- def ->[B](y: B): (Contexts, B)
-
final
def
==(arg0: Any): Boolean
The expression
x == that
is equivalent toif (x eq null) that eq null else x.equals(that)
.The expression
x == that
is equivalent toif (x eq null) that eq null else x.equals(that)
.- returns
true
if the receiver object is equivalent to the argument;false
otherwise.
- Definition Classes
- AnyRef → Any
- val ImportType: Global.ImportType.type
- def ambiguousDefnAndImport(owner: Global.Symbol, imp: Analyzer.ImportInfo): Global.LookupAmbiguous
- def ambiguousImports(imp1: Analyzer.ImportInfo, imp2: Analyzer.ImportInfo): Global.LookupAmbiguous
-
final
def
asInstanceOf[T0]: T0
Cast the receiver object to be of type
T0
.Cast the receiver object to be of type
T0
.Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression
1.asInstanceOf[String]
will throw aClassCastException
at runtime, while the expressionList(1).asInstanceOf[List[String]]
will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.- returns
the receiver object.
- Definition Classes
- Any
- Exceptions thrown
ClassCastException
if the receiver object is not an instance of the erasure of typeT0
.
-
def
clone(): AnyRef
Create a copy of the receiver object.
Create a copy of the receiver object.
The default implementation of the
clone
method is platform dependent.- returns
a copy of the receiver object.
- Attributes
- protected[java.lang]
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
- Note
not specified by SLS as a member of AnyRef
- def ensuring(cond: (Contexts) ⇒ Boolean, msg: ⇒ Any): Contexts
- def ensuring(cond: (Contexts) ⇒ Boolean): Contexts
- def ensuring(cond: Boolean, msg: ⇒ Any): Contexts
- def ensuring(cond: Boolean): Contexts
-
final
def
eq(arg0: AnyRef): Boolean
Tests whether the argument (
that
) is a reference to the receiver object (this
).Tests whether the argument (
that
) is a reference to the receiver object (this
).The
eq
method implements an equivalence relation on non-null instances ofAnyRef
, and has three additional properties:- It is consistent: for any non-null instances
x
andy
of typeAnyRef
, multiple invocations ofx.eq(y)
consistently returnstrue
or consistently returnsfalse
. - For any non-null instance
x
of typeAnyRef
,x.eq(null)
andnull.eq(x)
returnsfalse
. null.eq(null)
returnstrue
.
When overriding the
equals
orhashCode
methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2
), they should be equal to each other (o1 == o2
) and they should hash to the same value (o1.hashCode == o2.hashCode
).- returns
true
if the argument is a reference to the receiver object;false
otherwise.
- Definition Classes
- AnyRef
- It is consistent: for any non-null instances
-
def
equals(arg0: Any): Boolean
The equality method for reference types.
-
def
finalize(): Unit
Called by the garbage collector on the receiver object when there are no more references to the object.
Called by the garbage collector on the receiver object when there are no more references to the object.
The details of when and if the
finalize
method is invoked, as well as the interaction betweenfinalize
and non-local returns and exceptions, are all platform dependent.- Attributes
- protected[java.lang]
- Definition Classes
- AnyRef
- Annotations
- @throws( classOf[java.lang.Throwable] )
- Note
not specified by SLS as a member of AnyRef
- def formatted(fmtstr: String): String
-
final
def
getClass(): Class[_]
Returns the runtime class representation of the object.
Returns the runtime class representation of the object.
- returns
a class object corresponding to the runtime type of the receiver.
- Definition Classes
- AnyRef → Any
-
def
hashCode(): Int
The hashCode method for reference types.
-
final
def
isInstanceOf[T0]: Boolean
Test whether the dynamic type of the receiver object is
T0
.Test whether the dynamic type of the receiver object is
T0
.Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression
1.isInstanceOf[String]
will returnfalse
, while the expressionList(1).isInstanceOf[List[String]]
will returntrue
. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.- returns
true
if the receiver object is an instance of erasure of typeT0
;false
otherwise.
- Definition Classes
- Any
- var lastAccessCheckDetails: String
-
final
def
ne(arg0: AnyRef): Boolean
Equivalent to
!(this eq that)
.Equivalent to
!(this eq that)
.- returns
true
if the argument is not a reference to the receiver object;false
otherwise.
- Definition Classes
- AnyRef
-
final
def
notify(): Unit
Wakes up a single thread that is waiting on the receiver object's monitor.
Wakes up a single thread that is waiting on the receiver object's monitor.
- Definition Classes
- AnyRef
- Note
not specified by SLS as a member of AnyRef
-
final
def
notifyAll(): Unit
Wakes up all threads that are waiting on the receiver object's monitor.
Wakes up all threads that are waiting on the receiver object's monitor.
- Definition Classes
- AnyRef
- Note
not specified by SLS as a member of AnyRef
-
def
onTreeCheckerError(pos: Global.Position, msg: String): Unit
- Attributes
- protected
- def resetContexts(): Unit
- def rootContext(unit: Global.CompilationUnit, tree: Global.Tree = EmptyTree, throwing: Boolean = false, checking: Boolean = false): Analyzer.Context
- def rootContextPostTyper(unit: Global.CompilationUnit, tree: Global.Tree = EmptyTree): Analyzer.Context
-
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
- if option
-
final
def
synchronized[T0](arg0: ⇒ T0): T0
- Definition Classes
- AnyRef
-
def
toString(): String
Creates a String representation of this object.
Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.
- returns
a String representation of the object.
- Definition Classes
- AnyRef → Any
-
final
def
wait(): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
final
def
wait(arg0: Long, arg1: Int): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
final
def
wait(arg0: Long): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
- def warnUnusedImports(unit: Global.CompilationUnit): Unit
- def →[B](y: B): (Contexts, B)
- object NoContext extends Analyzer.Context
The Scala compiler API.
The following resources are useful for Scala plugin/compiler development: