package scala.tools.nsc package typechecker trait Tags { self: Analyzer => import global._ import definitions._ trait Tag { self: Typer => private def resolveTag(pos: Position, taggedTp: Type, allowMaterialization: Boolean) = beforeTyper { def wrapper (tree: => Tree): Tree = if (allowMaterialization) (context.withMacrosEnabled[Tree](tree)) else (context.withMacrosDisabled[Tree](tree)) wrapper(inferImplicit( EmptyTree, taggedTp, /*reportAmbiguous =*/ true, /*isView =*/ false, /*context =*/ context, /*saveAmbiguousDivergent =*/ true, /*pos =*/ pos ).tree) } /** Finds in scope or materializes a ClassTag. * Should be used instead of ClassManifest every time compiler needs to persist an erasure. * * Once upon a time, we had an `ErasureTag` which was to `ClassTag` the same that `AbsTypeTag` is for `TypeTag`. * However we found out that we don't really need this concept, so it got removed. * * @param pos Position for error reporting. Please, provide meaningful value. * @param tp Type we're looking a ClassTag for, e.g. resolveClassTag(pos, IntClass.tpe) will look for ClassTag[Int]. * @param allowMaterialization If true (default) then the resolver is allowed to launch materialization macros when there's no class tag in scope. * If false then materialization macros are prohibited from running. * * @returns Tree that represents an `scala.reflect.ClassTag` for `tp` if everything is okay. * EmptyTree if the result contains unresolved (i.e. not spliced) type parameters and abstract type members. * EmptyTree if `allowMaterialization` is false, and there is no class tag in scope. */ def resolveClassTag(pos: Position, tp: Type, allowMaterialization: Boolean = true): Tree = { val taggedTp = appliedType(ClassTagClass.typeConstructor, List(tp)) resolveTag(pos, taggedTp, allowMaterialization) } /** Finds in scope or materializes an AbsTypeTag (if `concrete` is false) or a TypeTag (if `concrete` is true). * * @param pos Position for error reporting. Please, provide meaningful value. * @param pre Prefix that represents a universe this type tag will be bound to. * If `pre` is set to `NoType`, then any type tag in scope will do, regardless of its affiliation. * If `pre` is set to `NoType`, and tag resolution involves materialization, then `mkBasisPrefix` will be used. * @param tp Type we're looking a TypeTag for, e.g. resolveTypeTag(pos, reflectBasisPrefix, IntClass.tpe, false) will look for scala.reflect.basis.TypeTag[Int]. * @param concrete If true then the result must not contain unresolved (i.e. not spliced) type parameters and abstract type members. * If false then the function will always succeed (abstract types will be reified as free types). * @param allowMaterialization If true (default) then the resolver is allowed to launch materialization macros when there's no type tag in scope. * If false then materialization macros are prohibited from running. * * @returns Tree that represents a `scala.reflect.TypeTag` for `tp` if everything is okay. * EmptyTree if `concrete` is true and the result contains unresolved (i.e. not spliced) type parameters and abstract type members. * EmptyTree if `allowMaterialization` is false, and there is no array tag in scope. */ def resolveTypeTag(pos: Position, pre: Type, tp: Type, concrete: Boolean, allowMaterialization: Boolean = true): Tree = { val tagSym = if (concrete) TypeTagClass else AbsTypeTagClass val tagTp = if (pre == NoType) TypeRef(BaseUniverseClass.toTypeConstructor, tagSym, List(tp)) else singleType(pre, pre member tagSym.name) val taggedTp = appliedType(tagTp, List(tp)) resolveTag(pos, taggedTp, allowMaterialization) } } }