Scala “编译错误”;未找到值…”;宏扩展后
我是scala宏的新手。我正在为XDB客户端编写一个自动JSON编写器/读取器 读者看起来像:Scala “编译错误”;未找到值…”;宏扩展后,scala,scala-macros,scala-reflect,Scala,Scala Macros,Scala Reflect,我是scala宏的新手。我正在为XDB客户端编写一个自动JSON编写器/读取器 读者看起来像: trait InfluxReader[T] { def read(js: JsArray): T } Warning:scalac: { final class $anon extends InfluxReader[Test] { def <init>() = { super.<init>(); () }; def r
trait InfluxReader[T] {
def read(js: JsArray): T
}
Warning:scalac: {
final class $anon extends InfluxReader[Test] {
def <init>() = {
super.<init>();
()
};
def read(js: JsArray): Test = js.elements.tail match {
case Vector(JsNumber(age), JsString(name)) => new Test(age = age, name = name)
case _ => throw DeserializationException("Can\'t deserialize Test object")
}
};
new $anon()
}
流入格式:
object InfluxFormatter {
/**
* Generate InfluxReader for type ${A}
*/
def reader[A]: InfluxReader[A] = macro InfluxFormatterImpl.reader_impl[A]
}
InfluxFormatterImpl:
private[macros] object InfluxFormatterImpl {
/***
* Generate AST for current type at compile time.
* @tparam T - Type parameter for whom will be generated AST
*/
def reader_impl[T: c.WeakTypeTag](c: blackbox.Context): c.universe.Tree = {
import c.universe._
val tpe = c.weakTypeOf[T]
val methods = tpe.decls.toList collect {
case m: MethodSymbol if m.isCaseAccessor =>
m.name.decodedName.toString -> m.returnType.dealias
}
if (methods.lengthCompare(1) < 0) {
c.abort(c.enclosingPosition, "Type parameter must be a case class with more then 1 fields")
}
val bool = typeOf[Boolean].dealias
val int = typeOf[Int].dealias
val long = typeOf[Long].dealias
val double = typeOf[Double].dealias
val string = typeOf[String].dealias
val params = methods
.map(_._1)
.sorted
.map(v => TermName(v))
.map(v => q"$v = $v")
val jsParams = methods
.sortBy(_._1) // influx return results in alphabetical order
.map { case (k, v) => TermName(k) -> v }
.map {
case (name, `bool`) => q"JsBoolean($name)"
case (name, `string`) => q"JsString($name)"
case (name, `int`) => q"JsNumber($name)"
case (name, `long`) => q"JsNumber($name)"
case (name, `double`) => q"JsNumber($name)"
case (_, other) => c.abort(c.enclosingPosition, s"Unknown type $other")
}
val failureMsg = s"Can't deserialize $tpe object"
val result = q"""
new InfluxReader[$tpe] {
def read(js: JsArray): $tpe = js.elements.tail match {
case Vector(..$jsParams) => new $tpe(..$params)
case _ => throw DeserializationException($failureMsg)
}
}"""
result
}
}
编译MacroReaderSpec
失败,出现编译错误:
Error:(14, 36) not found: value age
val rd = InfluxFormatter.reader[Test]
Error:(14, 36) not found: value name
val rd = InfluxFormatter.reader[Test]
使用编译器选项“-Ymacro-debug-lite”
,它看起来像:
trait InfluxReader[T] {
def read(js: JsArray): T
}
Warning:scalac: {
final class $anon extends InfluxReader[Test] {
def <init>() = {
super.<init>();
()
};
def read(js: JsArray): Test = js.elements.tail match {
case Vector(JsNumber(age), JsString(name)) => new Test(age = age, name = name)
case _ => throw DeserializationException("Can\'t deserialize Test object")
}
};
new $anon()
}
为什么它找不到它?我认为它不能将其识别为模式匹配的表达式,也不能调用提取器。如果是,如何更改?也许它在某种程度上称之为“得分不足”?
我使用的是scala 2.12.4。SBT1.1.0。
可以找到源代码
谢谢大家。它通过使用
pq
quasikotes重写代码得到修复。此外,所有标识符必须包装到术语名(41;
。可以找到一个工作示例