Reifiers

Given a type, generate a tree that when compiled and executed produces the runtime class of the enclosing class or module. Returns EmptyTree if there does not exist an enclosing class or module.

Given a type, generate a tree that when compiled and executed produces the runtime class of the original type. If concrete is true, then this function will bail on types, who refer to abstract types (like ClassTag does).

Given a tree, generate a tree that when compiled and executed produces the original tree. For more information and examples see the documentation for Universe.reify.

The produced tree will be bound to the specified universe and mirror. Possible values for universe include universe.internal.gen.mkRuntimeUniverseRef. Possible values for mirror include EmptyTree (in that case the reifier will automatically pick an appropriate mirror).

This function is deeply connected to Universe.reify, a macro that reifies arbitrary expressions into runtime trees. They do very similar things (Universe.reify calls Context.reifyTree to implement itself), but they operate on different metalevels (see below).

Let's study the differences between Context.reifyTree and Universe.reify on an example of using them inside a fooMacro macro:

* Since reify itself is a macro, it will be executed when fooMacro is being compiled (metalevel -1) and will produce a tree that when evaluated during macro expansion of fooMacro (metalevel 0) will recreate the input tree.

This provides a facility analogous to quasi-quoting. Writing "reify{ expr }" will generate an AST that represents expr. Afterwards this AST (or its parts) can be used to construct the return value of fooMacro.

* reifyTree is evaluated during macro expansion (metalevel 0) and will produce a tree that when evaluated during the runtime of the program (metalevel 1) will recreate the input tree.

This provides a way to retain certain trees from macro expansion time to be inspected later, in the runtime. For example, DSL authors may find it useful to capture DSL snippets into ASTs that are then processed at runtime in a domain-specific way.

Also note the difference between universes of the runtime trees produced by two reifies:

* The result of compiling and running the result of reify will be bound to the Universe that called reify. This is possible because it's a macro, so it can generate whatever code it wishes.

* The result of compiling and running the result of reifyTree will be the prefix that needs to be passed explicitly. This happens because the Universe of the evaluated result is from a different metalevel than the Context the called reify.

Typical usage of this function is to retain some of the trees received/created by a macro into the form that can be inspected (via pattern matching) or compiled/run (by a reflective ToolBox) during the runtime.

Given a type, generate a tree that when compiled and executed produces the original type. The produced tree will be bound to the specified universe and mirror. For more information and examples see the documentation for Context.reifyTree and Universe.reify.

Undoes reification of a tree.

This reversion doesn't simply restore the original tree (that would lose the context of reification), but does something more involved that conforms to the following laws:

1) unreifyTree(reifyTree(tree)) != tree // unreified tree is tree + saved context // in current implementation, the result of unreify is opaque // i.e. there's no possibility to inspect underlying tree/context

2) reifyTree(unreifyTree(reifyTree(tree))) == reifyTree(tree) // the result of reifying a tree in its original context equals to // the result of reifying a tree along with its saved context

3) compileAndEval(unreifyTree(reifyTree(tree))) ~ compileAndEval(tree) // at runtime original and unreified trees are behaviorally equivalent

Test two objects for inequality.

Equivalent to x.hashCode except for boxed numeric types and null. 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. For null returns a hashcode where null.hashCode throws a NullPointerException.

The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).

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.

Create a copy of the receiver object.

The default implementation of the clone method is platform dependent.

Tests whether the argument (that) is a reference to the receiver object (this).

The eq method implements an equivalence relation on non-null instances of AnyRef, and has three additional 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 equality method for reference types. Default implementation delegates to eq.

See also equals in scala.Any.

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 between finalize and non-local returns and exceptions, are all platform dependent.

A representation that corresponds to the dynamic class of the receiver object.

The nature of the representation is platform dependent.

The hashCode method for reference types. See hashCode in scala.Any.

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.

Equivalent to !(this eq that).

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.

Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.