enumeratum.ValueEnumMacros.scala Maven / Gradle / Ivy
package enumeratum
import enumeratum.ContextUtils.Context
import scala.reflect.ClassTag
object ValueEnumMacros {
/**
* Finds ValueEntryType-typed objects in scope that have literal value:Int implementations
*
* Note, requires the ValueEntryType to have a 'value' member that has a literal value
*/
def findIntValueEntriesImpl[ValueEntryType: c.WeakTypeTag](c: Context): c.Expr[IndexedSeq[ValueEntryType]] = {
findValueEntriesImpl[ValueEntryType, ContextUtils.CTInt, Int](c)(identity)
}
/**
* Finds ValueEntryType-typed objects in scope that have literal value:Long implementations
*
* Note, requires the ValueEntryType to have a 'value' member that has a literal value
*/
def findLongValueEntriesImpl[ValueEntryType: c.WeakTypeTag](c: Context): c.Expr[IndexedSeq[ValueEntryType]] = {
findValueEntriesImpl[ValueEntryType, ContextUtils.CTLong, Long](c)(identity)
}
/**
* Finds ValueEntryType-typed objects in scope that have literal value:Short implementations
*
* Note
*
* - requires the ValueEntryType to have a 'value' member that has a literal value
* - the Short value should be a literal Int (do no need to cast .toShort).
*/
def findShortValueEntriesImpl[ValueEntryType: c.WeakTypeTag](c: Context): c.Expr[IndexedSeq[ValueEntryType]] = {
findValueEntriesImpl[ValueEntryType, ContextUtils.CTInt, Short](c)(_.toShort) // do a transform because there is no such thing as Short literals
}
/**
* Finds ValueEntryType-typed objects in scope that have literal value:String implementations
*
* Note
*
* - requires the ValueEntryType to have a 'value' member that has a literal value
*/
def findStringValueEntriesImpl[ValueEntryType: c.WeakTypeTag](c: Context): c.Expr[IndexedSeq[ValueEntryType]] = {
findValueEntriesImpl[ValueEntryType, String, String](c)(identity)
}
/**
* The method that does the heavy lifting.
*/
private[this] def findValueEntriesImpl[ValueEntryType: c.WeakTypeTag, ValueType: ClassTag, ProcessedValue](c: Context)(processFoundValues: ValueType => ProcessedValue): c.Expr[IndexedSeq[ValueEntryType]] = {
import c.universe._
val typeSymbol = weakTypeOf[ValueEntryType].typeSymbol
EnumMacros.validateType(c)(typeSymbol)
// Find the trees in the enclosing object that match the given ValueEntryType
val subclassTrees = EnumMacros.enclosedSubClassTrees(c)(typeSymbol)
// Find the parameters for the constructors of ValueEntryType
val valueEntryTypeConstructorsParams = findConstructorParamsLists[ValueEntryType](c)
// Identify the value:ValueType implementations for each of the trees we found and process them if required
val treeWithVals = findValuesForSubclassTrees[ValueType, ProcessedValue](c)(valueEntryTypeConstructorsParams, subclassTrees, processFoundValues)
// Make sure the processed found value implementations are unique
ensureUnique[ProcessedValue](c)(treeWithVals)
// Finish by building our Sequence
val subclassSymbols = treeWithVals.map(_.tree.symbol)
EnumMacros.buildSeqExpr[ValueEntryType](c)(subclassSymbols)
}
/**
* Returns a list of TreeWithVal (tree with value of type ProcessedValueType) for the given trees and transformation
*
* Will abort compilation if not all the trees provided have a literal value member/constructor argument
*/
private[this] def findValuesForSubclassTrees[ValueType: ClassTag, ProcessedValueType](c: Context)(valueEntryCTorsParams: List[List[c.universe.Name]], memberTrees: Seq[c.universe.Tree], processFoundValues: ValueType => ProcessedValueType): Seq[TreeWithVal[c.universe.Tree, ProcessedValueType]] = {
val treeWithValues = toTreeWithMaybeVals[ValueType, ProcessedValueType](c)(valueEntryCTorsParams, memberTrees, processFoundValues)
val (hasValueMember, lacksValueMember) = treeWithValues.partition(_.maybeValue.isDefined)
if (lacksValueMember.nonEmpty) {
val classTag = implicitly[ClassTag[ValueType]]
val lacksValueMemberStr = lacksValueMember.map(_.tree.symbol).mkString(", ")
c.abort(
c.enclosingPosition,
s"""
|It looks like not all of the members have a literal/constant 'value:${classTag.runtimeClass.getSimpleName}' declaration, namely: $lacksValueMemberStr.
|
|This can happen if:
|
|- The aforementioned members have their `value` supplied by a variable, or otherwise defined as a method
|
|If none of the above apply to your case, it's likely you have discovered an issue with Enumeratum, so please file an issue :)
""".stripMargin
)
}
hasValueMember.collect {
case TreeWithMaybeVal(tree, Some(v)) => TreeWithVal(tree, v)
}
}
/**
* Looks through the given trees and tries to find the proper value declaration/constructor argument.
*
* Aborts compilation if the value declaration/constructor is of the wrong type,
*/
private[this] def toTreeWithMaybeVals[ValueType: ClassTag, ProcessedValueType](c: Context)(valueEntryCTorsParams: List[List[c.universe.Name]], memberTrees: Seq[c.universe.Tree], processFoundValues: ValueType => ProcessedValueType): Seq[TreeWithMaybeVal[c.universe.Tree, ProcessedValueType]] = {
import c.universe._
val classTag = implicitly[ClassTag[ValueType]]
val valueTerm = ContextUtils.termName(c)("value")
// go through all the trees
memberTrees.map { declTree =>
val values = declTree.collect {
// The tree has a value declaration with a constant value.
case ValDef(_, termName, _, Literal(Constant(i: ValueType))) if termName == valueTerm => Some(i)
// The tree has a method call
case Apply(fun, args) => {
val valueArguments: List[Option[ValueType]] = valueEntryCTorsParams.collect {
// Find the constructor params list that matches the arguments list size of the method call
case paramTermNames if paramTermNames.size == args.size => {
val paramsWithArg = paramTermNames.zip(args)
paramsWithArg.collectFirst {
// found a (paramName, argument) parameter-argument pair where paramName is "value", and argument is a constant with the right type
case (`valueTerm`, Literal(Constant(i: ValueType))) => i
// found a (paramName, argument) parameter-argument pair where paramName is "value", and argument is a constant with the wrong type
case (`valueTerm`, Literal(Constant(i))) => c.abort(c.enclosingPosition, s"${declTree.symbol} has a value with the wrong type: $i:${i.getClass}, instead of ${classTag.runtimeClass}.")
/*
* found a (_, NamedArgument(argName, argument)) parameter-named pair where the argument is named "value" and the argument itself is of the right type
*/
case (_, AssignOrNamedArg(Ident(`valueTerm`), Literal(Constant(i: ValueType)))) => i
/*
* found a (_, NamedArgument(argName, argument)) parameter-named pair where the argument is named "value" and the argument itself is of the wrong type
*/
case (_, AssignOrNamedArg(Ident(`valueTerm`), Literal(Constant(i)))) => c.abort(c.enclosingPosition, s"${declTree.symbol} has a value with the wrong type: $i:${i.getClass}, instead of ${classTag.runtimeClass}")
}
}
}
// We only want the first such constructor argument
valueArguments.collectFirst { case Some(v) => v }
}
}
val processedValue = values.collectFirst { case Some(v) => processFoundValues(v) }
TreeWithMaybeVal(declTree, processedValue)
}
}
/**
* Given a type, finds the constructor params lists for it
*/
private[this] def findConstructorParamsLists[ValueEntryType: c.WeakTypeTag](c: Context): List[List[c.universe.Name]] = {
val valueEntryTypeTpe = implicitly[c.WeakTypeTag[ValueEntryType]].tpe
val valueEntryTypeTpeMembers = valueEntryTypeTpe.members
valueEntryTypeTpeMembers
.collect(ContextUtils.constructorsToParamNamesPF(c))
.toList
}
/**
* Ensures that we have unique values for trees, aborting otherwise with a message indicating which trees have the same symbol
*/
private[this] def ensureUnique[A](c: Context)(treeWithVals: Seq[TreeWithVal[c.universe.Tree, A]]): Unit = {
val membersWithValues = treeWithVals.map { treeWithVal =>
treeWithVal.tree.symbol -> treeWithVal.value
}
val groupedByValue = membersWithValues.groupBy(_._2).mapValues(_.map(_._1))
val (valuesWithOneSymbol, valuesWithMoreThanOneSymbol) = groupedByValue.partition(_._2.size <= 1)
if (valuesWithOneSymbol.size != membersWithValues.toMap.keys.size) {
c.abort(
c.enclosingPosition,
s"It does not look like you have unique values. Each of the following values correspond to more than one member: $valuesWithMoreThanOneSymbol"
)
}
}
// Helper case classes
private[this] case class TreeWithMaybeVal[CTree, T](tree: CTree, maybeValue: Option[T])
private[this] case class TreeWithVal[CTree, T](tree: CTree, value: T)
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