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Diffstat (limited to 'src/library-aux/scala/Any.scala')
| -rw-r--r-- | src/library-aux/scala/Any.scala | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/src/library-aux/scala/Any.scala b/src/library-aux/scala/Any.scala new file mode 100644 index 0000000000..a97e5f050b --- /dev/null +++ b/src/library-aux/scala/Any.scala @@ -0,0 +1,105 @@ +/* __ *\ +** ________ ___ / / ___ Scala API ** +** / __/ __// _ | / / / _ | (c) 2002-2010, LAMP/EPFL ** +** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ ** +** /____/\___/_/ |_/____/_/ | | ** +** |/ ** +\* */ + +package scala + +/** Class `Any` is the root of the Scala class hierarchy. Every class in a Scala + * execution environment inherits directly or indirectly from this class. + */ +abstract class Any { + /** Compares the receiver object (`this`) with the argument object (`that`) for equivalence. + * + * The default implementations of this method is an [[http://en.wikipedia.org/wiki/Equivalence_relation equivalence relation]]: + * + * - 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 usually necessary to override `hashCode` to ensure that + * objects which are "equal" (`o1.equals(o2)` returns `true`) hash to the same [[scala.Int]]. + * (`o1.hashCode.equals(o2.hashCode)`). + * + * @param that the object to compare against this object for equality. + * @return `true` if the receiver object is equivalent to the argument; `false` otherwise. + */ + def equals(that: Any): Boolean + + /** Calculate 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. + * + * @return the hash code value for this object. + */ + def hashCode: Int + + /** Returns a string representation of the object. + * + * The default representation is platform dependent. + * + * @return a string representation of the object. + */ + def toString: String + + /** Test two objects for equality. + * + * @param that the object to compare against this object for equality. + * @return `true` if the receiver object is equivalent to the argument; `false` otherwise. + */ + final def ==(that: Any): Boolean = this equals that + + /** Test two objects for inequality. + * + * @param that the object to compare against this object for equality. + * @return `true` if !(this == that), false otherwise. + */ + final def != (that: Any): Boolean = !(this == that) + + /** Equivalent to `x.hashCode` except for boxed numeric types. + * 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. + * + * @return a hash value consistent with == + */ + final def ## : Int = sys.error("##") + + /** 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 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 specified type. + * + * @return `true` if the receiver object is an instance of erasure of type `T0`; `false` otherwise. + */ + def isInstanceOf[T0]: Boolean = sys.error("isInstanceOf") + + /** 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 a `ClassCastException` at + * runtime, while the expression `List(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. + * + * @throws ClassCastException if the receiver object is not an instance of the erasure of type `T0`. + * @return the receiver object. + */ + def asInstanceOf[T0]: T0 = sys.error("asInstanceOf") +} |