We need a whole WithFilter class to honor the "doesn't create a new collection" contract even though it seems unlikely to matter much in a collection with max size 1.
o != arg0
is the same as !(o == (arg0))
.
o != arg0
is the same as !(o == (arg0))
.
the object to compare against this object for dis-equality.
false
if the receiver object is equivalent to the argument; true
otherwise.
o == arg0
is the same as if (o eq null) arg0 eq null else o.equals(arg0)
.
o == arg0
is the same as if (o eq null) arg0 eq null else o.equals(arg0)
.
the object to compare against this object for equality.
true
if the receiver object is equivalent to the argument; false
otherwise.
o == arg0
is the same as o.equals(arg0)
.
o == arg0
is the same as o.equals(arg0)
.
the object to compare against this object for equality.
true
if the receiver object is equivalent to the argument; false
otherwise.
This method is used to cast the receiver object to be of type T0
.
This method is used to 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 expression1.asInstanceOf[String]
will throw a ClassCastException
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 typed.
the receiver object.
A method that should be called from every well-designed equals method that is open to be overridden in a subclass.
This method creates and returns a copy of the receiver object.
This method creates and returns a copy of the receiver object.
The default implementation of the clone
method is platform dependent.
a copy of the receiver object.
Returns a Some containing the result of
applying pf
to this Option's contained
value, if this option is
nonempty and pf
is defined for that value.
Returns a Some containing the result of
applying pf
to this Option's contained
value, if this option is
nonempty and pf
is defined for that value.
Returns None
otherwise.
the partial function.
the result of applying pf
to this Option's
value (if possible), or None
.
This method is used to test whether the argument (arg0
) is a reference to the
receiver object (this
).
This method is used to test whether the argument (arg0
) is a reference to the
receiver object (this
).
The eq
method implements an [http://en.wikipedia.org/wiki/Equivalence_relation equivalence relation] on
non-null instances of AnyRef
:
* It is reflexive: for any non-null instance x
of type AnyRef
, x.eq(x)
returns true
.
* It is symmetric: for any non-null instances x
and y
of type AnyRef
, x.eq(y)
returns true
if and
only if y.eq(x)
returns true
.
* It is transitive: for any non-null instances x
, y
, and z
of type AnyRef
if x.eq(y)
returns true
and y.eq(z)
returns true
, then x.eq(z)
returns true
.
Additionally, the eq
method has three other properties.
* It is consistent: for any non-null instances x
and y
of type AnyRef
, multiple invocations of
x.eq(y)
consistently returns true
or consistently returns false
.
* For any non-null instance x
of type AnyRef
, x.eq(null)
and null.eq(x)
returns false
.
* null.eq(null)
returns true
.
When overriding the equals
or hashCode
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
).
the object to compare against this object for reference equality.
true
if the argument is a reference to the receiver object; false
otherwise.
The equality method defined in AnyRef
.
Returns true if this option is nonempty and the predicatep
returns true when applied to this Option's value.
Returns this Option if it is nonempty and applying the predicate p
to
this Option's value returns true.
This method is called by the garbage collector on the receiver object when garbage collection determines that there are no more references to the object.
This method is called by the garbage collector on the receiver object when garbage collection determines that there are no more references to the object.
The details of when and if the finalize
method are invoked, as well as the interaction between finalize
and non-local returns and exceptions, are all platform dependent.
Returns the result of applying f
to this Option's value if
this Option is nonempty.
Apply the given procedure f
to the option's value,
if it is nonempty.
Apply the given procedure f
to the option's value,
if it is nonempty. Otherwise, do nothing.
the procedure to apply.
flatMap
map
Returns the option's value.
Returns a representation that corresponds to the dynamic class of the receiver object.
Returns a representation that corresponds to the dynamic class of the receiver object.
The nature of the representation is platform dependent.
a representation that corresponds to the dynamic class of the receiver object.
Returns the option's value if the option is nonempty, otherwise
return the result of evaluating default
.
Returns the option's value if the option is nonempty, otherwise
return the result of evaluating default
.
the default expression.
Returns a hash code value for the object.
Returns a hash code value for the object.
The default hashing algorithm is platform dependent.
Note that it is allowed for two objects to have identical hash codes (o1.hashCode.equals(o2.hashCode)
) yet
not be equal (o1.equals(o2)
returns false
). A degenerate implementation could always return 0
.
However, it is required that if two objects are equal (o1.equals(o2)
returns true
) that they have
identical hash codes (o1.hashCode.equals(o2.hashCode)
). Therefore, when overriding this method, be sure
to verify that the behavior is consistent with the equals
method.
the hash code value for the object.
Returns true if the option is an instance of Some, false otherwise.
Returns true if the option is None
, false otherwise.
This method is used to test whether the dynamic type of the receiver object is T0
.
This method is used to test whether the dynamic type of the receiver object is T0
.
Note that the test result of the test is modulo Scala's erasure semantics. Therefore the expression1.isInstanceOf[String]
will return false
, while the expression List(1).isInstanceOf[List[String]]
will
return true
. 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 typed.
true
if the receiver object is an instance of erasure of type T0
; false
otherwise.
Returns a singleton iterator returning the Option's value if it is nonempty, or an empty iterator if the option is empty.
Returns a Some containing the result of applying f
to this Option's
value if this Option is nonempty.
o.ne(arg0)
is the same as !(o.eq(arg0))
.
o.ne(arg0)
is the same as !(o.eq(arg0))
.
the object to compare against this object for reference dis-equality.
false
if the argument is not a reference to the receiver object; true
otherwise.
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.
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.
Returns this Option if it is nonempty,
otherwise return the result of evaluating alternative
.
Returns the option's value if it is nonempty,
or null
if it is empty.
return k for a product A(x_1,...,x_k)
For a product A(x_1,...,x_k)
, returns x_(n+1)
for 0 <= n < k
use productIterator instead
An iterator that returns all fields of this product
An iterator that returns all fields of this product
By default the empty string.
Returns a Right containing the given
argument right
if this is empty, or
a Left containing this Option's value
if this Option is nonempty.
Returns a singleton list containing the Option's value if it is nonempty, or the empty list if the Option is empty.
Returns a Left containing the given
argument left
if this Option is empty, or
a Right containing this Option's value if
this is nonempty.
Returns a string representation of the object.
Returns a string representation of the object.
The default representation is platform dependent.
a string representation of the object.
Necessary to keep Option from being implicitly converted to
Iterable in for
comprehensions.
Class
Some[A]
represents existing values of typeA
.version
1.0, 16/07/2003