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Diffstat (limited to 'src/library/scala/reflect/macro/Context.scala')
| -rw-r--r-- | src/library/scala/reflect/macro/Context.scala | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/src/library/scala/reflect/macro/Context.scala b/src/library/scala/reflect/macro/Context.scala index d0a2787fdf..ebbd4735e5 100644 --- a/src/library/scala/reflect/macro/Context.scala +++ b/src/library/scala/reflect/macro/Context.scala @@ -12,4 +12,25 @@ trait Context extends api.Universe { */ def referenceCapturedVariable(id: Ident): Tree + /** Given a tree or type, generate a tree that when executed at runtime produces the original tree or type. + * For instance, given the abstract syntax tree representation of the `x + 1` expression: + * + * Apply(Select(Ident("x"), "+"), List(Literal(Constant(1)))) + * + * The reifier transforms it to the following tree: + * + * $mr.Apply($mr.Select($mr.Ident($mr.newFreeVar("x", <Int>, x), "+"), List($mr.Literal($mr.Constant(1)))))) + * + * The transformation looks mostly straightforward, but it has its tricky parts: + * * Reifier retains symbols and types defined outside the reified tree, however + * locally defined entities get erased and replaced with their original trees + * * Free variables are detected and wrapped in symbols of the type FreeVar + * * Mutable variables that are accessed from a local function are wrapped in refs + * * Since reified trees can be compiled outside of the scope they've been created in, + * special measures are taken to ensure that all freeVars remain visible + * + * 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. + */ + def reify(tree: Tree): Tree } |