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import java.util.regex.Pattern
import scala.reflect.internal.SymbolTable
import scala.reflect.macros.blackbox._
import language.experimental.macros
object Macro {
/**
* Equivalent to Pattern.compile(s), but caches the compiled regex (using invokedynamic) if
* `s` is a literal.
*/
def compilePattern(s: String): Pattern = macro Macro.impl
def impl(c: Context)(s: c.Tree): c.Tree = {
def Indy(bootstrapMethod: c.Symbol, bootstrapArgs: List[c.universe.Literal]): c.Tree = {
val symtab = c.universe.asInstanceOf[SymbolTable]
import symtab._
val dummySymbol = NoSymbol.newTermSymbol(TermName("compile")).setInfo(NullaryMethodType(typeOf[Pattern]))
val args: List[Tree] = Literal(Constant(bootstrapMethod)).setType(NoType) :: bootstrapArgs.asInstanceOf[List[Tree]]
val result = ApplyDynamic(Ident(dummySymbol).setType(dummySymbol.info), args)
result.setType(dummySymbol.info.resultType)
result.asInstanceOf[c.Tree]
}
import c.universe._
s match {
case l @ Literal(Constant(s: String)) =>
val boostrapSym = typeOf[test.Bootstrap].companion.member(TermName("bootstrap"))
Indy(boostrapSym, l :: Nil)
case _ =>
q"_root_.java.util.regex.Pattern.compile($s)"
}
}
}
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