A few handy operations which leverage the extra bit of information
available in partial functions. Examples:
import PartialFunction._
def strangeConditional(other: Any): Boolean = cond(other) {
case x: String if x == "abc" || x == "def" => true
case x: Int => true
}
def onlyInt(v: Any): Option[Int] = condOpt(v) { case x: Int => x }
Creates a Boolean test based on a value and a partial function
Creates a Boolean test based on a value and a partial function.
It behaves like a 'match' statement with an implied 'case _ => false'
following the supplied cases.
x
the value to test
pf
the partial function
returns
true, iff x is in the domain of pf and pf(x) == true.
Transforms a PartialFunction[T, U] pf' into Function1[T, Option[U]] f'
whose result is Some(x) if the argument is in pf's domain and None otherwise,
and applies it to the value x'
Transforms a PartialFunction[T, U] pf' into Function1[T, Option[U]] f'
whose result is Some(x) if the argument is in pf's domain and None otherwise,
and applies it to the value x'. In effect, it is a 'match' statement
which wraps all case results in Some(_) and adds 'case _ => None' to the end.
x
the value to test
pf
the PartialFunction[T, U]
returns
Some(pf(x)) if pf isDefinedAt x, None otherwise.
defequals(arg0: Any): Boolean
This method is used to compare the receiver object (this)
with the argument object (arg0) for equivalence
This method is used to compare the receiver object (this)
with the argument object (arg0) for equivalence.
It is reflexive: for any instance x of type Any,
x.equals(x) should return true.
It is symmetric: for any instances x and y of type
Any, x.equals(y) should return true if and only
if y.equals(x) returns true.
It is transitive: for any instances
x, y, and z of type AnyRef
if x.equals(y) returns true and
y.equals(z) returns
true, then x.equals(z) should return true.
If you override this method, you should verify that
your implementation remains an equivalence relation.
Additionally, when overriding this method it is often necessary to
override hashCode to ensure that objects that are
"equal" (o1.equals(o2) returns true)
hash to the same Int
(o1.hashCode.equals(o2.hashCode)).
arg0
the object to compare against this object for equality.
returns
true if the receiver object is equivalent to the argument; false otherwise.
definition classes: AnyRef ⇐ Any
defhashCode(): Int
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.
A few handy operations which leverage the extra bit of information available in partial functions. Examples: