diff options
Diffstat (limited to 'src/compiler/scala/tools/nsc/typechecker/EtaExpansion.scala')
| -rw-r--r-- | src/compiler/scala/tools/nsc/typechecker/EtaExpansion.scala | 54 |
1 files changed, 22 insertions, 32 deletions
diff --git a/src/compiler/scala/tools/nsc/typechecker/EtaExpansion.scala b/src/compiler/scala/tools/nsc/typechecker/EtaExpansion.scala index 7092f00bff..5f4fa499b6 100644 --- a/src/compiler/scala/tools/nsc/typechecker/EtaExpansion.scala +++ b/src/compiler/scala/tools/nsc/typechecker/EtaExpansion.scala @@ -15,39 +15,29 @@ import symtab.Flags._ * @version 1.0 */ trait EtaExpansion { self: Analyzer => - import global._ - object etaExpansion { - private def isMatch(vparam: ValDef, arg: Tree) = arg match { - case Ident(name) => vparam.name == name - case _ => false - } - - def unapply(tree: Tree): Option[(List[ValDef], Tree, List[Tree])] = tree match { - case Function(vparams, Apply(fn, args)) if (vparams corresponds args)(isMatch) => - Some((vparams, fn, args)) - case _ => - None - } - } - - /** <p> - * Expand partial function applications of type `type`. - * </p><pre> - * p.f(es_1)...(es_n) - * ==> { - * <b>private synthetic val</b> eta$f = p.f // if p is not stable - * ... - * <b>private synthetic val</b> eta$e_i = e_i // if e_i is not stable - * ... - * (ps_1 => ... => ps_m => eta$f([es_1])...([es_m])(ps_1)...(ps_m)) - * }</pre> - * <p> - * tree is already attributed - * </p> - */ - def etaExpand(unit : CompilationUnit, tree: Tree, typer: Typer): Tree = { + /** Expand partial method application `p.f(es_1)...(es_n)`. + * + * We expand this to the following block, which evaluates + * the target of the application and its supplied arguments if needed (they are not stable), + * and then wraps a Function that abstracts over the missing arguments. + * + * ``` + * { + * private synthetic val eta$f = p.f // if p is not stable + * ... + * private synthetic val eta$e_i = e_i // if e_i is not stable + * ... + * (ps_1 => ... => ps_m => eta$f([es_1])...([es_m])(ps_1)...(ps_m)) + * } + * ``` + * + * This is called from instantiateToMethodType after type checking `tree`, + * and we realize we have a method type, where a function type (builtin or SAM) is expected. + * + **/ + def etaExpand(unit: CompilationUnit, tree: Tree, typer: Typer): Tree = { val tpe = tree.tpe var cnt = 0 // for NoPosition def freshName() = { @@ -115,7 +105,7 @@ trait EtaExpansion { self: Analyzer => val origTpe = sym.tpe val isRepeated = definitions.isRepeatedParamType(origTpe) // SI-4176 Don't leak A* in eta-expanded function types. See t4176b.scala - val droppedStarTpe = if (settings.etaExpandKeepsStar) origTpe else dropIllegalStarTypes(origTpe) + val droppedStarTpe = dropIllegalStarTypes(origTpe) val valDef = ValDef(Modifiers(SYNTHETIC | PARAM), sym.name.toTermName, TypeTree(droppedStarTpe), EmptyTree) (valDef, isRepeated) } |