重写Scala函数的toString的宏注释
如何编写宏注释,该注释在使用中看起来像重写Scala函数的toString的宏注释,scala,macros,annotations,scala-macros,scalameta,Scala,Macros,Annotations,Scala Macros,Scalameta,如何编写宏注释,该注释在使用中看起来像@named(“+2”)\uU2,并生成: new (Int => Int) { override def toString(): String = "+2" def apply(x: Int): Int = x + 2 } 可以创建返回匿名函数的宏。您没有完全获得所需的语法,似乎@在方法中不起作用 import scala.language.experimental.macros import scala.reflect.macros._
@named(“+2”)\uU2
,并生成:
new (Int => Int) {
override def toString(): String = "+2"
def apply(x: Int): Int = x + 2
}
可以创建返回匿名函数的宏。您没有完全获得所需的语法,似乎@在方法中不起作用
import scala.language.experimental.macros
import scala.reflect.macros._
object Named {
def build[T, R](name: String)(applyFunc: T => R): T => R = macro Named.impl[T, R]
def impl[T: c.WeakTypeTag, R: c.WeakTypeTag](c: whitebox.Context)(name: c.Expr[String])(applyFunc: c.Expr[T => R]): c.Expr[T => R] = {
import c.universe._
val functionType = weakTypeOf[T]
val resultType = weakTypeOf[R]
c.Expr[T => R](
c.typecheck(q"""
new ($functionType => $resultType) {
override def toString() = $name
def apply(x: $functionType): $resultType = $applyFunc(x)
}
"""))
}
}
然后使用此宏生成您自己的函数:
class NamedTest {
@Test
def testNamed() = {
val b = Named.build[Int, Int]("+2")(_ + 2)
assertEquals(4, b(2))
assertEquals("+2", b.toString)
}
}
可以创建返回匿名函数的宏。您没有完全获得所需的语法,似乎@在方法中不起作用
import scala.language.experimental.macros
import scala.reflect.macros._
object Named {
def build[T, R](name: String)(applyFunc: T => R): T => R = macro Named.impl[T, R]
def impl[T: c.WeakTypeTag, R: c.WeakTypeTag](c: whitebox.Context)(name: c.Expr[String])(applyFunc: c.Expr[T => R]): c.Expr[T => R] = {
import c.universe._
val functionType = weakTypeOf[T]
val resultType = weakTypeOf[R]
c.Expr[T => R](
c.typecheck(q"""
new ($functionType => $resultType) {
override def toString() = $name
def apply(x: $functionType): $resultType = $applyFunc(x)
}
"""))
}
}
然后使用此宏生成您自己的函数:
class NamedTest {
@Test
def testNamed() = {
val b = Named.build[Int, Int]("+2")(_ + 2)
assertEquals(4, b(2))
assertEquals("+2", b.toString)
}
}
正确的语法是((:Int)+2):@named(“+2”)
。不幸的是,注释表达式的宏注释不会展开
最简单的就是使用
object Named {
def build[T, R](name: String)(applyFunc: T => R): T => R = new (T => R) {
override def toString() = name
def apply(x: T): R = applyFunc(x)
}
}
没有任何宏
否则,可以展开表达式上的注释:
build.sbt(关于生成源的sbt文档)
project/build.sbt
project/Generator.scala
annotations/src/main/scala/com/example/annotations/named.scala
helpers/src/main/scala/com/example/helpers/TypedFunctions.scala
在/src/main/scala/com/example/App.scala中
out/target/scala-2.13/src_managed/main/scala/com/example/App.scala(在sbt之后);project out;clean;compile“
)
另一个例子是正确的语法是((:Int)+2):@named(“+2”)
。不幸的是,注释表达式的宏注释不会展开
最简单的就是使用
object Named {
def build[T, R](name: String)(applyFunc: T => R): T => R = new (T => R) {
override def toString() = name
def apply(x: T): R = applyFunc(x)
}
}
没有任何宏
否则,可以展开表达式上的注释:
build.sbt(关于生成源的sbt文档)
project/build.sbt
project/Generator.scala
annotations/src/main/scala/com/example/annotations/named.scala
helpers/src/main/scala/com/example/helpers/TypedFunctions.scala
在/src/main/scala/com/example/App.scala中
out/target/scala-2.13/src_managed/main/scala/com/example/App.scala(在sbt之后);project out;clean;compile“
)
另一个例子是宏应用于什么类型的对象?Function1(带参数的函数)宏应用于什么类型的对象?Function1(带参数的函数)如果使用
命名。build
您似乎根本不需要def
宏:名为{def build[T,R](名称:String)的对象(applyFunc:T=>R):T=>R=new(T=>R){override def toString()=name;def apply(x:T):R=applyFunc(x)}
如果您使用Named.build
您似乎根本不需要def
宏:名为{def build[T,R](名称:String)(applyFunc:T=>R):T=>R=new(T=>R){override def toString()=name;def apply(x:T):R=applyFunc(x)}}
import scala.meta._
object Transformer {
val getNamedAnnotationParam: PartialFunction[Mod, Lit] = {
case mod"@named(...${List(List(s: Lit))})" => s
}
val isNamedAnnotated: Mod => Boolean = getNamedAnnotationParam.lift(_).isDefined
def transform(input: String): String = transform(input.parse[Source].get).toString
def transform(input: Tree): Tree = input.transform {
case q"package $eref { ..$stats }" =>
val stats1 = stats.filter {
case q"import ..${List(importer"annotations.{..$importeesnel}")}" => false
case _ => true
}
q"package $eref { ..$stats1 }"
case q"$expr: ..@$annotsnel" if annotsnel.exists(isNamedAnnotated) =>
val annotsnel1 = annotsnel.filterNot(isNamedAnnotated)
val name = annotsnel.collect(getNamedAnnotationParam).head
val expr1 = expr match {
case q"(..$params) => $expr2" =>
val params1 = params.map {
case param"..$mods $name: ${Some(tpe)} = $expropt" =>
param"..$mods $name: ${Some(tpe)} = $expropt"
case param"..$mods $name: ${None} = $expropt" =>
param"..$mods $name: scala.Any = $expropt"
}
val domain = params1.map {
case param"..$mods $name: $tpeopt = $expropt" => tpeopt.get
}
q"""
val typed = com.example.helpers.${Term.Name("TypedFunction" + params.length)}($expr)
new ((..$domain) => typed.CoDomain) {
override def toString(): String = $name
def apply(..$params1): typed.CoDomain = $expr2
}
"""
case e => e
}
if (annotsnel1.nonEmpty)
q"$expr1: ..@$annotsnel1"
else q"$expr1"
}
}
package com.example.annotations
import scala.annotation.StaticAnnotation
class named(name: String) extends StaticAnnotation
package com.example.helpers
sealed trait TypedFunctions[_CoDomain] {
type CoDomain = _CoDomain
}
case class TypedFunction0[_CoDomain](f: () => _CoDomain) extends TypedFunctions[_CoDomain]
case class TypedFunction1[_Domain, _CoDomain](f: _Domain => _CoDomain) extends TypedFunctions[_CoDomain]
case class TypedFunction2[_Domain1, _Domain2, _CoDomain](f: (_Domain1, _Domain2) => _CoDomain) extends TypedFunctions[_CoDomain]
case class TypedFunction3[_Domain1, _Domain2, _Domain3, _CoDomain](f: (_Domain1, _Domain2, _Domain3) => _CoDomain) extends TypedFunctions[_CoDomain]
package com.example
import annotations.named
object App {
(((x: Int) => x + 2): @named("+2"))
(((x: Int, y: Int) => x + y): @named("+"))
}
package com.example
object App {
{
val typed = com.example.helpers.TypedFunction1 { (x: Int) => x + 2 }
new (Int => typed.CoDomain) {
override def toString(): String = "+2"
def apply(x: Int): typed.CoDomain = x + 2
}
}
{
val typed = com.example.helpers.TypedFunction2 { (x: Int, y: Int) => x + y }
new ((Int, Int) => typed.CoDomain) {
override def toString(): String = "+"
def apply(x: Int, y: Int): typed.CoDomain = x + y
}
}
}