Trait scala.reflect.api.Exprs.Expr

Companion object Expr

trait Expr[+T] extends Equals with Serializable

Expr wraps an abstract syntax tree and tags it with its type. The main source of information about exprs is the scala.reflect.api.Exprs page.

Source
Exprs.scala
Linear Supertypes
java.io.Serializable, Equals, AnyRef, Any

Abstract Value Members

abstract def actualType: Universe.Type

abstract def in[U <: Universe with Singleton](otherMirror: Mirror[U]): in.U.Expr[T]

abstract val mirror: Universe.Mirror

abstract def splice: T

A dummy method to mark expression splicing in reification.

It should only be used within a reify call, which eliminates the splice call and embeds the wrapped tree into the reified surrounding expression. If used alone splice throws an exception when called at runtime.

If you want to use an Expr in reification of some Scala code, you need to splice it in. For an expr of type Expr[T], where T has a method foo, the following code

reify{ expr.splice.foo }

uses splice to turn an expr of type Expr[T] into a value of type T in the context of reify.

It is equivalent to

Select( expr.tree, TermName("foo") )

The following example code however does not compile

reify{ expr.foo }

because expr of type Expr[T] itself does not have a method foo.

Annotations
@compileTimeOnly("splice must be enclosed within a reify {} block")

abstract def staticType: Universe.Type

Type of the wrapped expression tree as provided during creation.

When exprs are created by the compiler, staticType represents a statically known type of the tree as calculated at that point by the compiler.

abstract def tree: Universe.Tree

abstract val value: T

A dummy value to denote cross-stage path-dependent type dependencies.

For example for the following macro definition:

class X { type T }
object Macros { def foo(x: X): x.T = macro Impls.foo_impl }

The corresponding macro implementation should have the following signature (note how the return type denotes path-dependency on x):

object Impls { def foo_impl(c: Context)(x: c.Expr[X]): c.Expr[x.value.T] = ... }
Annotations
@compileTimeOnly("cannot use value except for signatures of macro implementations")

Concrete Value Members

final def !=(arg0: Any): Boolean

Definition Classes
AnyRef → Any

final def ##(): Int

Definition Classes
AnyRef → Any

def +(other: String): String

Implicit
This member is added by an implicit conversion from Universe.Expr[T] toany2stringadd[Universe.Expr[T]] performed by method any2stringadd in scala.Predef.
Definition Classes
any2stringadd

def ->[B](y: B): (Universe.Expr[T], B)

Implicit
This member is added by an implicit conversion from Universe.Expr[T] toArrowAssoc[Universe.Expr[T]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc
Annotations
@inline()

final def ==(arg0: Any): Boolean

Definition Classes
AnyRef → Any

final def asInstanceOf[T0]: T0

Definition Classes
Any

def canEqual(x: Any): Boolean

Definition Classes
Expr → Equals

def clone(): AnyRef

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

def ensuring(cond: (Universe.Expr[T]) => Boolean, msg: => Any): Universe.Expr[T]

Implicit
This member is added by an implicit conversion from Universe.Expr[T] toEnsuring[Universe.Expr[T]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring

def ensuring(cond: (Universe.Expr[T]) => Boolean): Universe.Expr[T]

Implicit
This member is added by an implicit conversion from Universe.Expr[T] toEnsuring[Universe.Expr[T]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring

def ensuring(cond: Boolean, msg: => Any): Universe.Expr[T]

Implicit
This member is added by an implicit conversion from Universe.Expr[T] toEnsuring[Universe.Expr[T]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring

def ensuring(cond: Boolean): Universe.Expr[T]

Implicit
This member is added by an implicit conversion from Universe.Expr[T] toEnsuring[Universe.Expr[T]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring

final def eq(arg0: AnyRef): Boolean

Definition Classes
AnyRef

def equals(x: Any): Boolean

Definition Classes
Expr → Equals → AnyRef → Any

def finalize(): Unit

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

def formatted(fmtstr: String): String

Implicit
This member is added by an implicit conversion from Universe.Expr[T] toStringFormat[Universe.Expr[T]] performed by method StringFormat in scala.Predef.
Definition Classes
StringFormat
Annotations
@inline()

final def getClass(): Class[_ <: AnyRef]

Definition Classes
AnyRef → Any
Annotations
@native()

def hashCode(): Int

Definition Classes
Expr → AnyRef → Any

final def isInstanceOf[T0]: Boolean

Definition Classes
Any

final def ne(arg0: AnyRef): Boolean

Definition Classes
AnyRef

final def notify(): Unit

Definition Classes
AnyRef
Annotations
@native()

final def notifyAll(): Unit

Definition Classes
AnyRef
Annotations
@native()

final def synchronized[T0](arg0: => T0): T0

Definition Classes
AnyRef

def toString(): String

Definition Classes
Expr → AnyRef → Any

final def wait(): Unit

Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])

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

Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])

final def wait(arg0: Long): Unit

Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException]) @native()

© 2002-2019 EPFL, with contributions from Lightbend.
Licensed under the Apache License, Version 2.0.
https://www.scala-lang.org/api/2.13.0/scala-reflect/scala/reflect/api/Exprs$Expr.html