trait Typers extends AnyRef
EXPERIMENTAL
A slice of the Scala macros context that partially exposes the type checker to macro writers.
- Self Type
- blackbox.Context
- Source
- Typers.scala
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Type Members
- type TypecheckException = macros.TypecheckException
- See also
scala.reflect.macros.TypecheckException
- abstract type TypecheckMode
Represents mode of operations of the typechecker underlying
c.typecheck
calls.Represents mode of operations of the typechecker underlying
c.typecheck
calls. Is necessary since the shape of the typechecked tree alone is not enough to guess how it should be typechecked. Can be TERMmode (typecheck as a term), TYPEmode (typecheck as a type) or PATTERNmode (typecheck as a pattern).
Abstract Value Members
- abstract val PATTERNmode: blackbox.Context.TypecheckMode
Indicates that an argument to
c.typecheck
should be typechecked as a pattern. - abstract val TERMmode: blackbox.Context.TypecheckMode
Indicates that an argument to
c.typecheck
should be typechecked as a term.Indicates that an argument to
c.typecheck
should be typechecked as a term. This is the default typechecking mode in Scala 2.11 and the only one supported in Scala 2.10. - abstract val TYPEmode: blackbox.Context.TypecheckMode
Indicates that an argument to
c.typecheck
should be typechecked as a type. - abstract def inferImplicitValue(pt: blackbox.Context.Type, silent: Boolean = true, withMacrosDisabled: Boolean = false, pos: blackbox.Context.Position = enclosingPosition): blackbox.Context.Tree
Infers an implicit value of the expected type
pt
in the macro callsite context.Infers an implicit value of the expected type
pt
in the macro callsite context. Optionalpos
parameter provides a position that will be associated with the implicit search.If
silent
is false,TypecheckException
will be thrown in case of an inference error. Ifsilent
is true, the typecheck is silent and will returnEmptyTree
if an error occurs. Such errors don't vanish and can be inspected by turning on -Xlog-implicits. Unlike intypecheck
,silent
is true by default.- Exceptions thrown
- abstract def inferImplicitView(tree: blackbox.Context.Tree, from: blackbox.Context.Type, to: blackbox.Context.Type, silent: Boolean = true, withMacrosDisabled: Boolean = false, pos: blackbox.Context.Position = enclosingPosition): blackbox.Context.Tree
Infers an implicit view from the provided tree
tree
of the typefrom
to the typeto
in the macro callsite context.Infers an implicit view from the provided tree
tree
of the typefrom
to the typeto
in the macro callsite context. Optionalpos
parameter provides a position that will be associated with the implicit search.If
silent
is false,TypecheckException
will be thrown in case of an inference error. Ifsilent
is true, the typecheck is silent and will returnEmptyTree
if an error occurs. Such errors don't vanish and can be inspected by turning on -Xlog-implicits. Unlike intypecheck
,silent
is true by default.- Exceptions thrown
- abstract def openMacros: List[blackbox.Context]
Contexts that represent macros in-flight, including the current one.
Contexts that represent macros in-flight, including the current one. Very much like a stack trace, but for macros only. Can be useful for interoperating with other macros and for imposing compiler-friendly limits on macro expansion.
Is also priceless for emitting sane error messages for macros that are called by other macros on synthetic (i.e. position-less) trees. In that dire case navigate the
openMacros
stack, and it will most likely contain at least one macro with a position-ful macro application. SeeenclosingPosition
for a default implementation of this logic.Unlike
enclosingMacros
, this is a def, which means that it gets recalculated on every invocation, so it might change depending on what is going on during macro expansion. - abstract def typecheck(tree: blackbox.Context.Tree, mode: blackbox.Context.TypecheckMode = TERMmode, pt: blackbox.Context.Type = universe.WildcardType, silent: Boolean = false, withImplicitViewsDisabled: Boolean = false, withMacrosDisabled: Boolean = false): blackbox.Context.Tree
Typechecks the provided tree against the expected type
pt
in the macro callsite context under typechecking mode specified inmode
with TERMmode being default.Typechecks the provided tree against the expected type
pt
in the macro callsite context under typechecking mode specified inmode
with TERMmode being default. This populates symbols and types of the tree and possibly transforms it to reflect certain desugarings.If
silent
is false,TypecheckException
will be thrown in case of a typecheck error. Ifsilent
is true, the typecheck is silent and will returnEmptyTree
if an error occurs. Such errors don't vanish and can be inspected by turning on -Ymacro-debug-verbose. Unlike ininferImplicitValue
andinferImplicitView
,silent
is false by default.Typechecking can be steered with the following optional parameters:
withImplicitViewsDisabled
recursively prohibits implicit views (though, implicit vals will still be looked up and filled in), default value is falsewithMacrosDisabled
recursively prohibits macro expansions and macro-based implicits, default value is false- Exceptions thrown
- abstract def untypecheck(tree: blackbox.Context.Tree): blackbox.Context.Tree
In the current implementation of Scala's reflection API, untyped trees (also known as parser trees or unattributed trees) are observationally different from typed trees (also known as typer trees, typechecked trees or attributed trees),
In the current implementation of Scala's reflection API, untyped trees (also known as parser trees or unattributed trees) are observationally different from typed trees (also known as typer trees, typechecked trees or attributed trees),
Usually, if some compiler API takes a tree, then both untyped and typed trees will do. However in some cases, only untyped or only typed trees are appropriate. For example, Evals.eval only accepts untyped trees and one can only splice typed trees inside typed trees. Therefore in the current reflection API, there is a need in functions that go back and forth between untyped and typed trees. For this we have typecheck and
untypecheck
.Note that
untypecheck
is currently afflicted by https://github.com/scala/bug/issues/5464, which makes it sometimes corrupt trees so that they don't make sense anymore. Unfortunately, there's no workaround for that. We plan to fix this issue soon, but for now please keep it in mind. - abstract def resetLocalAttrs(tree: blackbox.Context.Tree): blackbox.Context.Tree
Recursively resets locally defined symbols and types in a given tree.
Recursively resets locally defined symbols and types in a given tree. WARNING: Don't use this API, go for untypecheck instead.
- Annotations
- @deprecated
- Deprecated
(Since version 2.11.0) use
c.untypecheck
instead
Concrete Value Members
- final def !=(arg0: Any): Boolean
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- final def ##: Int
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- def +(other: String): String
- def ->[B](y: B): (Typers, B)
- final def ==(arg0: Any): Boolean
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- AnyRef → Any
- val TypecheckException: macros.TypecheckException.type
- See also
scala.reflect.macros.TypecheckException
- final def asInstanceOf[T0]: T0
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- protected[lang]
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- @throws(classOf[java.lang.CloneNotSupportedException]) @native()
- def ensuring(cond: (Typers) => Boolean, msg: => Any): Typers
- def ensuring(cond: (Typers) => Boolean): Typers
- def ensuring(cond: Boolean, msg: => Any): Typers
- def ensuring(cond: Boolean): Typers
- final def eq(arg0: AnyRef): Boolean
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Deprecated Value Members
- def typeCheck(tree: blackbox.Context.Tree, pt: blackbox.Context.Type = universe.WildcardType, silent: Boolean = false, withImplicitViewsDisabled: Boolean = false, withMacrosDisabled: Boolean = false): blackbox.Context.Tree
- Annotations
- @deprecated
- Deprecated
(Since version 2.11.0) use
c.typecheck
instead- See also
Typers.typecheck
- def →[B](y: B): (Typers, B)
- Implicit
- This member is added by an implicit conversion from Typers toArrowAssoc[Typers] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use
->
instead. If you still wish to display it as one character, consider using a font with programming ligatures such as Fira Code.