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
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- Expr
- Serializable
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- Equals
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- by Ensuring
- by ArrowAssoc
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Abstract Value Members
-
abstract
def
actualType: Universe.Type
Type of the wrapped expression tree as found in the underlying tree.
-
abstract
def
in[U <: Universe with Singleton](otherMirror: Mirror[U]): in.U.Expr[T]
Migrates the expression into another mirror, jumping into a different universe if necessary.
-
abstract
val
mirror: Universe.Mirror
Underlying mirror of this expr.
-
abstract
def
splice: T
A dummy method to mark expression splicing in reification.
A dummy method to mark expression splicing in reification.
It should only be used within a
reify
call, which eliminates thesplice
call and embeds the wrapped tree into the reified surrounding expression. If used alonesplice
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]
, whereT
has a methodfoo
, the following codereify{ 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( ... )
-
abstract
def
staticType: Universe.Type
Type of the wrapped expression tree as provided during creation.
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
The Scala abstract syntax tree representing the wrapped expression.
-
abstract
val
value: T
A dummy value to denote cross-stage path-dependent type dependencies.
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( ... )
Concrete 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
- Implicit
- This member is added by an implicit conversion from Universe.Expr[T] to any2stringadd[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] to ArrowAssoc[Universe.Expr[T]] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
- Annotations
- @inline()
-
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
-
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
canEqual(x: Any): Boolean
- Definition Classes
- Expr → Equals
-
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: (Universe.Expr[T]) ⇒ Boolean, msg: ⇒ Any): Universe.Expr[T]
- Implicit
- This member is added by an implicit conversion from Universe.Expr[T] to Ensuring[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] to Ensuring[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] to Ensuring[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] to Ensuring[Universe.Expr[T]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
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(x: 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
- Implicit
- This member is added by an implicit conversion from Universe.Expr[T] to StringFormat[Universe.Expr[T]] performed by method StringFormat in scala.Predef.
- Definition Classes
- StringFormat
- Annotations
- @inline()
-
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
-
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
-
final
def
synchronized[T0](arg0: ⇒ T0): T0
- Definition Classes
- AnyRef
-
def
toString(): String
Creates a String representation of this object.
-
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
→[B](y: B): (Universe.Expr[T], B)
- Implicit
- This member is added by an implicit conversion from Universe.Expr[T] to ArrowAssoc[Universe.Expr[T]] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc