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scala3-compiler-bootstrapped
package dotty.tools
package dotc
package ast
import core.*
import Flags.*, Trees.*, Types.*, Contexts.*
import Names.*, StdNames.*, NameOps.*, Symbols.*
import Annotations.Annotation
import NameKinds.ContextBoundParamName
import typer.ConstFold
import reporting.trace
import Decorators.*
import Constants.Constant
import scala.collection.mutable
import scala.annotation.tailrec
trait TreeInfo[T <: Untyped] { self: Trees.Instance[T] =>
def unsplice(tree: Trees.Tree[T]): Trees.Tree[T] = tree
def isDeclarationOrTypeDef(tree: Tree): Boolean = unsplice(tree) match {
case DefDef(_, _, _, EmptyTree)
| ValDef(_, _, EmptyTree)
| TypeDef(_, _) => true
case _ => false
}
def isOpAssign(tree: Tree): Boolean = unsplice(tree) match {
case Apply(fn, _ :: _) =>
unsplice(fn) match {
case Select(_, name) if name.isOpAssignmentName => true
case _ => false
}
case _ => false
}
class MatchingArgs(params: List[Symbol], args: List[Tree])(using Context) {
def foreach(f: (Symbol, Tree) => Unit): Boolean = {
def recur(params: List[Symbol], args: List[Tree]): Boolean = params match {
case Nil => args.isEmpty
case param :: params1 =>
if (param.info.isRepeatedParam) {
for (arg <- args) f(param, arg)
true
}
else args match {
case Nil => false
case arg :: args1 =>
f(param, args.head)
recur(params1, args1)
}
}
recur(params, args)
}
def zipped: List[(Symbol, Tree)] = map((_, _))
def map[R](f: (Symbol, Tree) => R): List[R] = {
val b = List.newBuilder[R]
foreach(b += f(_, _))
b.result()
}
}
/** The method part of an application node, possibly enclosed in a block
* with only valdefs as statements. the reason for also considering blocks
* is that named arguments can transform a call into a block, e.g.
* (b = foo, a = bar)
* is transformed to
* { val x$1 = foo
* val x$2 = bar
* (x$2, x$1)
* }
*/
def methPart(tree: Tree): Tree = stripApply(tree) match {
case TypeApply(fn, _) => methPart(fn)
case AppliedTypeTree(fn, _) => methPart(fn) // !!! should not be needed
case Block(stats, expr) => methPart(expr)
case mp => mp
}
/** If this is an application, its function part, stripping all
* Apply nodes (but leaving TypeApply nodes in). Otherwise the tree itself.
*/
def stripApply(tree: Tree): Tree = unsplice(tree) match {
case Apply(fn, _) => stripApply(fn)
case _ => tree
}
/** If this is a block, its expression part */
def stripBlock(tree: Tree): Tree = unsplice(tree) match {
case Block(_, expr) => stripBlock(expr)
case Inlined(_, _, expr) => stripBlock(expr)
case _ => tree
}
def stripInlined(tree: Tree): Tree = unsplice(tree) match {
case Inlined(_, _, expr) => stripInlined(expr)
case _ => tree
}
def stripAnnotated(tree: Tree): Tree = tree match {
case Annotated(arg, _) => arg
case _ => tree
}
def stripTyped(tree: Tree): Tree = unsplice(tree) match
case Typed(expr, _) =>
stripTyped(expr)
case _ =>
tree
def stripNamedArg(tree: Tree) = tree match
case NamedArg(_, arg) => arg
case _ => tree
/** The number of arguments in an application */
def numArgs(tree: Tree): Int = unsplice(tree) match {
case Apply(fn, args) => numArgs(fn) + args.length
case TypeApply(fn, _) => numArgs(fn)
case Block(_, expr) => numArgs(expr)
case _ => 0
}
/** The type arguments of a possibly curried call */
def typeArgss(tree: Tree): List[List[Tree]] =
@tailrec
def loop(tree: Tree, argss: List[List[Tree]]): List[List[Tree]] = tree match
case TypeApply(fn, args) => loop(fn, args :: argss)
case Apply(fn, args) => loop(fn, argss)
case _ => argss
loop(tree, Nil)
/** The term arguments of a possibly curried call */
def termArgss(tree: Tree): List[List[Tree]] =
@tailrec
def loop(tree: Tree, argss: List[List[Tree]]): List[List[Tree]] = tree match
case Apply(fn, args) => loop(fn, args :: argss)
case TypeApply(fn, args) => loop(fn, argss)
case _ => argss
loop(tree, Nil)
/** All term arguments of an application in a single flattened list */
def allTermArguments(tree: Tree): List[Tree] = unsplice(tree) match {
case Apply(fn, args) => allTermArguments(fn) ::: args
case TypeApply(fn, args) => allTermArguments(fn)
case Block(_, expr) => allTermArguments(expr)
case _ => Nil
}
/** All type and term arguments of an application in a single flattened list */
def allArguments(tree: Tree): List[Tree] = unsplice(tree) match {
case Apply(fn, args) => allArguments(fn) ::: args
case TypeApply(fn, args) => allArguments(fn) ::: args
case Block(_, expr) => allArguments(expr)
case _ => Nil
}
/** Is tree explicitly parameterized with type arguments? */
def hasExplicitTypeArgs(tree: Tree): Boolean = tree match
case TypeApply(tycon, args) =>
args.exists(arg => !arg.span.isZeroExtent && !tycon.span.contains(arg.span))
case _ => false
/** Is tree a path? */
def isPath(tree: Tree): Boolean = unsplice(tree) match {
case Ident(_) | This(_) | Super(_, _) => true
case Select(qual, _) => isPath(qual)
case _ => false
}
/** Is tree a self constructor call this(...)? I.e. a call to a constructor of the
* same object?
*/
def isSelfConstrCall(tree: Tree): Boolean = methPart(tree) match {
case Ident(nme.CONSTRUCTOR) | Select(This(_), nme.CONSTRUCTOR) => true
case _ => false
}
/** Is tree a super constructor call?
*/
def isSuperConstrCall(tree: Tree): Boolean = methPart(tree) match {
case Select(Super(_, _), nme.CONSTRUCTOR) => true
case _ => false
}
def isSuperSelection(tree: Tree): Boolean = unsplice(tree) match {
case Select(Super(_, _), _) => true
case _ => false
}
def isSelfOrSuperConstrCall(tree: Tree): Boolean = methPart(tree) match {
case Ident(nme.CONSTRUCTOR)
| Select(This(_), nme.CONSTRUCTOR)
| Select(Super(_, _), nme.CONSTRUCTOR) => true
case _ => false
}
/** Is tree a backquoted identifier or definition */
def isBackquoted(tree: Tree): Boolean = tree.hasAttachment(Backquoted)
/** Is tree a variable pattern? */
def isVarPattern(pat: Tree): Boolean = unsplice(pat) match {
case x: Ident => x.name.isVarPattern && !isBackquoted(x)
case _ => false
}
/** The first constructor definition in `stats` */
def firstConstructor(stats: List[Tree]): Tree = stats match {
case (meth: DefDef) :: _ if meth.name.isConstructorName => meth
case stat :: stats => firstConstructor(stats)
case nil => EmptyTree
}
/** Is tpt a vararg type of the form T* or => T*? */
def isRepeatedParamType(tpt: Tree)(using Context): Boolean = stripByNameType(tpt) match {
case tpt: TypeTree => tpt.typeOpt.isRepeatedParam
case AppliedTypeTree(Select(_, tpnme.REPEATED_PARAM_CLASS), _) => true
case _ => false
}
/** Is this argument node of the form *, or is it a reference to
* such an argument ? The latter case can happen when an argument is lifted.
*/
def isWildcardStarArg(tree: Tree)(using Context): Boolean = unbind(tree) match {
case Typed(Ident(nme.WILDCARD_STAR), _) => true
case Typed(_, Ident(tpnme.WILDCARD_STAR)) => true
case Typed(_, tpt: TypeTree) => tpt.typeOpt.isRepeatedParam
case NamedArg(_, arg) => isWildcardStarArg(arg)
case arg => arg.typeOpt.widen.isRepeatedParam
}
/** Is tree a type tree of the form `=> T` or (under pureFunctions) `{refs}-> T`? */
def isByNameType(tree: Tree)(using Context): Boolean =
stripByNameType(tree) ne tree
/** Strip `=> T` to `T` and (under pureFunctions) `{refs}-> T` to `T` */
def stripByNameType(tree: Tree)(using Context): Tree = unsplice(tree) match
case ByNameTypeTree(t1) => t1
case _ => tree
/** All type and value parameter symbols of this DefDef */
def allParamSyms(ddef: DefDef)(using Context): List[Symbol] =
ddef.paramss.flatten.map(_.symbol)
/** Does this argument list end with an argument of the form : _* ? */
def isWildcardStarArgList(trees: List[Tree])(using Context): Boolean =
trees.nonEmpty && isWildcardStarArg(trees.last)
/** Is the argument a wildcard argument of the form `_` or `x @ _`?
*/
def isWildcardArg(tree: Tree): Boolean = unbind(tree) match {
case Ident(nme.WILDCARD) => true
case _ => false
}
/** Does this list contain a named argument tree? */
def hasNamedArg(args: List[Any]): Boolean = args exists isNamedArg
val isNamedArg: Any => Boolean = (arg: Any) => arg.isInstanceOf[Trees.NamedArg[?]]
/** Is this pattern node a catch-all (wildcard or variable) pattern? */
def isDefaultCase(cdef: CaseDef): Boolean = cdef match {
case CaseDef(pat, EmptyTree, _) => isWildcardArg(pat)
case _ => false
}
/** Does this CaseDef catch Throwable? */
def catchesThrowable(cdef: CaseDef)(using Context): Boolean =
catchesAllOf(cdef, defn.ThrowableType)
/** Does this CaseDef catch everything of a certain Type? */
def catchesAllOf(cdef: CaseDef, threshold: Type)(using Context): Boolean =
isDefaultCase(cdef) ||
cdef.guard.isEmpty && {
unbind(cdef.pat) match {
case Typed(Ident(nme.WILDCARD), tpt) => threshold <:< tpt.typeOpt
case _ => false
}
}
/** Is this case guarded? */
def isGuardedCase(cdef: CaseDef): Boolean = cdef.guard ne EmptyTree
/** Is this parameter list a using clause? */
def isUsingClause(params: ParamClause)(using Context): Boolean = params match
case ValDefs(vparam :: _) =>
val sym = vparam.symbol
if sym.exists then sym.is(Given) else vparam.mods.is(Given)
case _ =>
false
def isUsingOrTypeParamClause(params: ParamClause)(using Context): Boolean = params match
case TypeDefs(_) => true
case _ => isUsingClause(params)
def isTypeParamClause(params: ParamClause)(using Context): Boolean = params match
case TypeDefs(_) => true
case _ => false
private val languageSubCategories = Set(nme.experimental, nme.deprecated)
/** If `path` looks like a language import, `Some(name)` where name
* is `experimental` if that sub-module is imported, and the empty
* term name otherwise.
*/
def languageImport(path: Tree): Option[TermName] = path match
case Select(p1, name: TermName) if languageSubCategories.contains(name) =>
languageImport(p1) match
case Some(EmptyTermName) => Some(name)
case _ => None
case p1: RefTree if p1.name == nme.language =>
p1.qualifier match
case EmptyTree => Some(EmptyTermName)
case p2: RefTree if p2.name == nme.scala =>
p2.qualifier match
case EmptyTree => Some(EmptyTermName)
case Ident(nme.ROOTPKG) => Some(EmptyTermName)
case _ => None
case _ => None
case _ => None
/** The underlying pattern ignoring any bindings */
def unbind(x: Tree): Tree = unsplice(x) match {
case Bind(_, y) => unbind(y)
case y => y
}
/** The largest subset of {NoInits, PureInterface} that a
* trait or class with these parents can have as flags.
*/
def parentsKind(parents: List[Tree])(using Context): FlagSet = parents match {
case Nil => NoInitsInterface
case Apply(_, _ :: _) :: _ | Block(_, _) :: _ => EmptyFlags
case _ :: parents1 => parentsKind(parents1)
}
/** Checks whether predicate `p` is true for all result parts of this expression,
* where we zoom into Ifs, Matches, and Blocks.
*/
def forallResults(tree: Tree, p: Tree => Boolean): Boolean = tree match {
case If(_, thenp, elsep) => forallResults(thenp, p) && forallResults(elsep, p)
case Match(_, cases) => cases forall (c => forallResults(c.body, p))
case Block(_, expr) => forallResults(expr, p)
case _ => p(tree)
}
/** The tree stripped of the possibly nested applications (term and type).
* The original tree if it's not an application.
*/
def appliedCore(tree: Tree): Tree = tree match {
case Apply(fn, _) => appliedCore(fn)
case TypeApply(fn, _) => appliedCore(fn)
case AppliedTypeTree(fn, _) => appliedCore(fn)
case tree => tree
}
/** Is tree an application with result `this.type`?
* Accept `b.addOne(x)` and also `xs(i) += x`
* where the op is an assignment operator.
*/
def isThisTypeResult(tree: Tree)(using Context): Boolean = appliedCore(tree) match {
case fun @ Select(receiver, op) =>
val argss = termArgss(tree)
tree.tpe match {
case ThisType(tref) =>
tref.symbol == receiver.symbol
case tref: TermRef =>
tref.symbol == receiver.symbol || argss.exists(_.exists(tref.symbol == _.symbol))
case _ =>
def checkSingle(sym: Symbol): Boolean =
(sym == receiver.symbol) || {
receiver match {
case Apply(_, _) => op.isOpAssignmentName // xs(i) += x
case _ => receiver.symbol != NoSymbol &&
(receiver.symbol.isGetter || receiver.symbol.isField) // xs.addOne(x) for var xs
}
}
@tailrec def loop(mt: Type): Boolean = mt match {
case m: MethodType =>
m.resType match {
case ThisType(tref) => checkSingle(tref.symbol)
case tref: TermRef => checkSingle(tref.symbol)
case restpe => loop(restpe)
}
case PolyType(_, restpe) => loop(restpe)
case _ => false
}
fun.symbol != NoSymbol && loop(fun.symbol.info)
}
case _ =>
tree.tpe.isInstanceOf[ThisType]
}
/** Under x.modularity: Extractor for `annotation.internal.WitnessNames(name_1, ..., name_n)`
* represented as an untyped or typed tree.
*/
object WitnessNamesAnnot:
def apply(names: List[TermName])(using Context): untpd.Tree =
untpd.TypedSplice(tpd.New(
defn.WitnessNamesAnnot.typeRef,
tpd.SeqLiteral(names.map(n => tpd.Literal(Constant(n.toString))), tpd.TypeTree(defn.StringType)) :: Nil
))
def unapply(tree: Tree)(using Context): Option[List[TermName]] =
unsplice(tree) match
case Apply(Select(New(tpt: tpd.TypeTree), nme.CONSTRUCTOR), SeqLiteral(elems, _) :: Nil) =>
tpt.tpe match
case tp: TypeRef if tp.name == tpnme.WitnessNames && tp.symbol == defn.WitnessNamesAnnot =>
Some:
elems.map:
case Literal(Constant(str: String)) =>
ContextBoundParamName.unmangle(str.toTermName.asSimpleName)
case _ => None
case _ => None
end WitnessNamesAnnot
}
trait UntypedTreeInfo extends TreeInfo[Untyped] { self: Trees.Instance[Untyped] =>
import untpd.*
/** The underlying tree when stripping any TypedSplice or Parens nodes */
override def unsplice(tree: Tree): Tree = tree match {
case TypedSplice(tree1) => tree1
case Parens(tree1) => unsplice(tree1)
case _ => tree
}
def functionWithUnknownParamType(tree: Tree): Option[Tree] = tree match {
case Function(args, _) =>
if (args.exists {
case ValDef(_, tpt, _) => tpt.isEmpty
case _ => false
}) Some(tree)
else None
case Match(EmptyTree, _) =>
Some(tree)
case Block(Nil, expr) =>
functionWithUnknownParamType(expr)
case NamedArg(_, expr) =>
functionWithUnknownParamType(expr)
case _ =>
None
}
def isFunctionWithUnknownParamType(tree: Tree): Boolean =
functionWithUnknownParamType(tree).isDefined
def isFunction(tree: Tree): Boolean = tree match
case Function(_, _) | Match(EmptyTree, _) => true
case Block(Nil, expr) => isFunction(expr)
case _ => false
/** Is `tree` an context function or closure, possibly nested in a block? */
def isContextualClosure(tree: Tree)(using Context): Boolean = unsplice(tree) match {
case tree: FunctionWithMods => tree.mods.is(Given)
case Function((param: untpd.ValDef) :: _, _) => param.mods.is(Given)
case Closure(_, meth, _) => true
case Block(Nil, expr) => isContextualClosure(expr)
case Block(DefDef(nme.ANON_FUN, params :: _, _, _) :: Nil, cl: Closure) =>
isUsingClause(params)
case _ => false
}
/** The largest subset of {NoInits, PureInterface} that a
* trait or class enclosing this statement can have as flags.
*/
private def defKind(tree: Tree)(using Context): FlagSet = unsplice(tree) match {
case EmptyTree | _: Import => NoInitsInterface
case tree: TypeDef => if (tree.isClassDef) NoInits else NoInitsInterface
case tree: DefDef =>
if tree.unforcedRhs == EmptyTree
&& tree.paramss.forall {
case ValDefs(vparams) => vparams.forall(_.rhs.isEmpty)
case _ => true
}
then
NoInitsInterface
else if tree.mods.is(Given) && tree.paramss.isEmpty then
EmptyFlags // might become a lazy val: TODO: check whether we need to suppress NoInits once we have new lazy val impl
else
NoInits
case tree: ValDef => if (tree.unforcedRhs == EmptyTree) NoInitsInterface else EmptyFlags
case _ => EmptyFlags
}
/** The largest subset of {NoInits, PureInterface} that a
* trait or class with this body can have as flags.
*/
def bodyKind(body: List[Tree])(using Context): FlagSet =
body.foldLeft(NoInitsInterface)((fs, stat) => fs & defKind(stat))
/** Info of a variable in a pattern: The named tree and its type */
type VarInfo = (NameTree, Tree)
/** An extractor for trees of the form `id` or `id: T` */
object IdPattern {
def unapply(tree: Tree)(using Context): Option[VarInfo] = tree match {
case id: Ident if id.name != nme.WILDCARD => Some(id, TypeTree())
case Typed(id: Ident, tpt) => Some((id, tpt))
case _ => None
}
}
/** Under pureFunctions: A builder and extractor for `=> T`, which is an alias for `->{cap} T`.
* Only trees of the form `=> T` are matched; trees written directly as `->{cap} T`
* are ignored by the extractor.
*/
object ImpureByNameTypeTree:
def apply(tp: Tree)(using Context): untpd.ByNameTypeTree =
untpd.ByNameTypeTree(
untpd.CapturesAndResult(
untpd.captureRoot.withSpan(tp.span.startPos) :: Nil, tp))
def unapply(tp: Tree)(using Context): Option[Tree] = tp match
case untpd.ByNameTypeTree(
untpd.CapturesAndResult(id @ Select(_, nme.CAPTURE_ROOT) :: Nil, result))
if id.span == result.span.startPos => Some(result)
case _ => None
end ImpureByNameTypeTree
}
trait TypedTreeInfo extends TreeInfo[Type] { self: Trees.Instance[Type] =>
import TreeInfo.*
import tpd.*
/** The purity level of this statement.
* @return Pure if statement has no side effects
* Idempotent if running the statement a second time has no side effects
* Impure otherwise
*/
def statPurity(tree: Tree)(using Context): PurityLevel = unsplice(tree) match {
case EmptyTree
| TypeDef(_, _)
| Import(_, _)
| DefDef(_, _, _, _) =>
Pure
case vdef @ ValDef(_, _, _) =>
if (vdef.symbol.flags is Mutable) Impure else exprPurity(vdef.rhs) `min` Pure
case _ =>
Impure
// TODO: It seem like this should be exprPurity(tree)
// But if we do that the repl/vars test break. Need to figure out why that's the case.
}
/** The purity level of this expression. See docs for PurityLevel for what that means
*
* Note that purity and idempotency are treated differently.
* References to modules and lazy vals are impure (side-effecting) both because
* side-effecting code may be executed and because the first reference
* takes a different code path than all to follow; but they are idempotent
* because running the expression a second time gives the cached result.
*/
def exprPurity(tree: Tree)(using Context): PurityLevel = unsplice(tree) match {
case EmptyTree
| This(_)
| Super(_, _)
| Literal(_) =>
PurePath
case Ident(_) =>
refPurity(tree)
case Select(qual, _) =>
if (tree.symbol.is(Erased)) Pure
else refPurity(tree) `min` exprPurity(qual)
case New(_) | Closure(_, _, _) =>
Pure
case TypeApply(fn, _) =>
if (fn.symbol.is(Erased) || fn.symbol == defn.QuotedTypeModule_of || fn.symbol == defn.Predef_classOf) Pure else exprPurity(fn)
case Apply(fn, args) =>
if isPureApply(tree, fn) then
minOf(exprPurity(fn), args.map(exprPurity)) `min` Pure
else if fn.symbol.is(Erased) then
Pure
else if fn.symbol.isStableMember /* && fn.symbol.is(Lazy) */ then
minOf(exprPurity(fn), args.map(exprPurity)) `min` Idempotent
else
Impure
case Typed(expr, _) =>
exprPurity(expr)
case Block(stats, expr) =>
minOf(exprPurity(expr), stats.map(statPurity))
case Inlined(_, bindings, expr) =>
minOf(exprPurity(expr), bindings.map(statPurity))
case NamedArg(_, expr) =>
exprPurity(expr)
case _ =>
Impure
}
private def minOf(l0: PurityLevel, ls: List[PurityLevel]) = ls.foldLeft(l0)(_ `min` _)
def isPurePath(tree: Tree)(using Context): Boolean = tree.tpe match {
case tpe: ConstantType => exprPurity(tree) >= Pure
case _ => exprPurity(tree) == PurePath
}
def isPureExpr(tree: Tree)(using Context): Boolean =
exprPurity(tree) >= Pure
def isIdempotentPath(tree: Tree)(using Context): Boolean = tree.tpe match {
case tpe: ConstantType => exprPurity(tree) >= Idempotent
case _ => exprPurity(tree) >= IdempotentPath
}
def isIdempotentExpr(tree: Tree)(using Context): Boolean =
exprPurity(tree) >= Idempotent
def isPureBinding(tree: Tree)(using Context): Boolean = statPurity(tree) >= Pure
/** Is the application `tree` with function part `fn` known to be pure?
* Function value and arguments can still be impure.
*/
def isPureApply(tree: Tree, fn: Tree)(using Context): Boolean =
def isKnownPureOp(sym: Symbol) =
sym.owner.isPrimitiveValueClass
|| sym.owner == defn.StringClass
|| defn.pureMethods.contains(sym)
tree.tpe.isInstanceOf[ConstantType] && tree.symbol != NoSymbol && isKnownPureOp(tree.symbol) // A constant expression with pure arguments is pure.
|| fn.symbol.isStableMember && fn.symbol.isConstructor // constructors of no-inits classes are stable
/** The purity level of this reference.
* @return
* PurePath if reference is (nonlazy and stable)
* or to a parameterized function
* or its type is a constant type
* IdempotentPath if reference is lazy and stable
* Impure otherwise
* @DarkDimius: need to make sure that lazy accessor methods have Lazy and Stable
* flags set.
*/
def refPurity(tree: Tree)(using Context): PurityLevel = {
val sym = tree.symbol
if (!tree.hasType) Impure
else if !tree.tpe.widen.isParameterless then PurePath
else if sym.is(Erased) then PurePath
else if tree.tpe.isInstanceOf[ConstantType] then PurePath
else if (!sym.isStableMember) Impure
else if (sym.is(Module))
if (sym.moduleClass.isNoInitsRealClass) PurePath else IdempotentPath
else if (sym.is(Lazy)) IdempotentPath
else if sym.isAllOf(InlineParam) then Impure
else PurePath
}
def isPureRef(tree: Tree)(using Context): Boolean =
refPurity(tree) == PurePath
def isIdempotentRef(tree: Tree)(using Context): Boolean =
refPurity(tree) >= IdempotentPath
/** (1) If `tree` is a constant expression, its value as a Literal,
* or `tree` itself otherwise.
*
* Note: Demanding idempotency instead of purity in literalize is strictly speaking too loose.
* Example
*
* object O { final val x = 42; println("43") }
* O.x
*
* Strictly speaking we can't replace `O.x` with `42`. But this would make
* most expressions non-constant. Maybe we can change the spec to accept this
* kind of eliding behavior. Or else enforce true purity in the compiler.
* The choice will be affected by what we will do with `inline` and with
* Singleton type bounds (see SIP 23). Presumably
*
* object O1 { val x: Singleton = 42; println("43") }
* object O2 { inline val x = 42; println("43") }
*
* should behave differently.
*
* O1.x should have the same effect as { println("43"); 42 }
*
* whereas
*
* O2.x = 42
*
* Revisit this issue once we have standardized on `inline`. Then we can demand
* purity of the prefix unless the selection goes to a inline val.
*
* Note: This method should be applied to all term tree nodes that are not literals,
* that can be idempotent, and that can have constant types. So far, only nodes
* of the following classes qualify:
*
* Ident
* Select
* TypeApply
*
* (2) A primitive unary operator expression `pre.op` where `op` is one of `+`, `-`, `~`, `!`
* that has a constant type `ConstantType(v)` but that is not a constant expression
* (i.e. `pre` has side-effects) is translated to
*
* { pre; v }
*
* (3) An expression `pre.getClass[..]()` that has a constant type `ConstantType(v)` but where
* `pre` has side-effects is translated to:
*
* { pre; v }
*
* This avoids the situation where we have a Select node that does not have a symbol.
*/
def constToLiteral(tree: Tree)(using Context): Tree = {
assert(!tree.isType)
val tree1 = ConstFold(tree)
tree1.tpe.widenTermRefExpr.dealias.normalized match {
case ConstantType(Constant(_: Type)) if tree.isInstanceOf[Block] =>
// We can't rewrite `{ class A; classOf[A] }` to `classOf[A]`, so we leave
// blocks returning a class literal alone, even if they're idempotent.
tree1
case ConstantType(value) =>
def dropOp(t: Tree): Tree = t match
case Select(pre, _) if t.tpe.isInstanceOf[ConstantType] =>
// it's a primitive unary operator
pre
case Apply(TypeApply(Select(pre, nme.getClass_), _), Nil) =>
pre
case _ =>
tree1
val countsAsPure =
if dropOp(tree1).symbol.isInlineVal
then isIdempotentExpr(tree1)
else isPureExpr(tree1)
if countsAsPure then Literal(value).withSpan(tree.span)
else
val pre = dropOp(tree1)
if pre eq tree1 then tree1
else
// it's a primitive unary operator or getClass call;
// Simplify `pre.op` to `{ pre; v }` where `v` is the value of `pre.op`
Block(pre :: Nil, Literal(value)).withSpan(tree.span)
case _ => tree1
}
}
def isExtMethodApply(tree: Tree)(using Context): Boolean = methPart(tree) match
case Inlined(call, _, _) => isExtMethodApply(call)
case tree @ Select(qual, nme.apply) => tree.symbol.is(ExtensionMethod) || isExtMethodApply(qual)
case tree => tree.symbol.is(ExtensionMethod)
/** Is symbol potentially a getter of a mutable variable?
*/
def mayBeVarGetter(sym: Symbol)(using Context): Boolean = {
def maybeGetterType(tpe: Type): Boolean = tpe match {
case _: ExprType => true
case tpe: MethodType => tpe.isImplicitMethod
case tpe: PolyType => maybeGetterType(tpe.resultType)
case _ => false
}
sym.owner.isClass && !sym.isStableMember && maybeGetterType(sym.info)
}
/** Is tree a reference to a mutable variable, or to a potential getter
* that has a setter in the same class?
*/
def isVariableOrGetter(tree: Tree)(using Context): Boolean = {
def sym = tree.symbol
def isVar = sym.is(Mutable)
def isGetter =
mayBeVarGetter(sym) && sym.owner.info.member(sym.name.asTermName.setterName).exists
unsplice(tree) match {
case Ident(_) => isVar
case Select(_, _) => isVar || isGetter
case Apply(_, _) =>
methPart(tree) match {
case Select(qual, nme.apply) => qual.tpe.member(nme.update).exists
case _ => false
}
case _ => false
}
}
/** Is tree a `this` node which belongs to `enclClass`? */
def isSelf(tree: Tree, enclClass: Symbol)(using Context): Boolean = unsplice(tree) match {
case This(_) => tree.symbol == enclClass
case _ => false
}
/** Strips layers of `.asInstanceOf[T]` / `_.$asInstanceOf[T]()` from an expression */
def stripCast(tree: Tree)(using Context): Tree = {
def isCast(sel: Tree) = sel.symbol.isTypeCast
unsplice(tree) match {
case TypeApply(sel @ Select(inner, _), _) if isCast(sel) =>
stripCast(inner)
case Apply(TypeApply(sel @ Select(inner, _), _), Nil) if isCast(sel) =>
stripCast(inner)
case t =>
t
}
}
/** The type and term arguments of a possibly curried call, in the order they are given */
def allArgss(tree: Tree): List[List[Tree]] =
@tailrec
def loop(tree: Tree, argss: List[List[Tree]]): List[List[Tree]] = tree match
case tree: GenericApply => loop(tree.fun, tree.args :: argss)
case _ => argss
loop(tree, Nil)
/** The function part of a possibly curried call. Unlike `methPart` this one does
* not decompose blocks
*/
def funPart(tree: Tree): Tree = tree match
case tree: GenericApply => funPart(tree.fun)
case tree => tree
/** Decompose a template body into parameters and other statements */
def decomposeTemplateBody(body: List[Tree])(using Context): (List[Tree], List[Tree]) =
body.partition {
case stat: TypeDef => stat.symbol is Flags.Param
case stat: ValOrDefDef =>
stat.symbol.is(Flags.ParamAccessor) && !stat.symbol.isSetter
case _ => false
}
/** An extractor for closures, possibly typed, and possibly including the
* definition of the anonymous def.
*/
object closure {
def unapply(tree: Tree)(using Context): Option[(List[Tree], Tree, Tree)] = tree match {
case Block((meth : DefDef) :: Nil, closure: Closure) if meth.symbol == closure.meth.symbol =>
unapply(closure)
case Block(Nil, expr) =>
unapply(expr)
case Closure(env, meth, tpt) =>
Some(env, meth, tpt)
case Typed(expr, _) =>
unapply(expr)
case _ => None
}
}
/** An extractor for a closure or a block ending in one. This was
* previously `closure` before that one was tightened.
*/
object blockEndingInClosure:
def unapply(tree: Tree)(using Context): Option[(List[Tree], Tree, Tree)] = tree match
case Block(_, expr) => unapply(expr)
case _ => closure.unapply(tree)
/** An extractor for def of a closure contained the block of the closure. */
object closureDef {
def unapply(tree: Tree)(using Context): Option[DefDef] = tree match {
case Block((meth : DefDef) :: Nil, closure: Closure) if meth.symbol == closure.meth.symbol =>
Some(meth)
case Block(Nil, expr) =>
unapply(expr)
case _ =>
None
}
}
/** An extractor for the method of a closure contained the block of the closure,
* possibly with type ascriptions.
*/
object possiblyTypedClosureDef:
def unapply(tree: Tree)(using Context): Option[DefDef] = tree match
case Typed(expr, _) => unapply(expr)
case _ => closureDef.unapply(tree)
/** If tree is a closure, its body, otherwise tree itself */
def closureBody(tree: Tree)(using Context): Tree = tree match {
case closureDef(meth) => meth.rhs
case _ => tree
}
/** Is `mdef` an eta-expansion of a method reference? To recognize this, we use
* the following criterion: A method definition is an eta expansion, if
* it contains at least one term paramter, the parameter has a zero extent span,
* and the right hand side is either an application or a closure with'
* an anonymous method that's itself characterized as an eta expansion.
*/
def isEtaExpansion(mdef: DefDef)(using Context): Boolean =
!rhsOfEtaExpansion(mdef).isEmpty
def rhsOfEtaExpansion(mdef: DefDef)(using Context): Tree = mdef.paramss match
case (param :: _) :: _ if param.asInstanceOf[Tree].span.isZeroExtent =>
mdef.rhs match
case rhs: Apply => rhs
case closureDef(mdef1) => rhsOfEtaExpansion(mdef1)
case _ => EmptyTree
case _ => EmptyTree
/** The variables defined by a pattern, in reverse order of their appearance. */
def patVars(tree: Tree)(using Context): List[Symbol] = {
val acc = new TreeAccumulator[List[Symbol]] { outer =>
def apply(syms: List[Symbol], tree: Tree)(using Context) = tree match {
case Bind(_, body) => apply(tree.symbol :: syms, body)
case Annotated(tree, id @ Ident(tpnme.BOUNDTYPE_ANNOT)) => apply(id.symbol :: syms, tree)
case QuotePattern(bindings, body, _) => quotePatVars(bindings.map(_.symbol) ::: syms, body)
case _ => foldOver(syms, tree)
}
private object quotePatVars extends TreeAccumulator[List[Symbol]] {
def apply(syms: List[Symbol], tree: Tree)(using Context) = tree match {
case SplicePattern(pat, _, _) => outer.apply(syms, pat)
case _ => foldOver(syms, tree)
}
}
}
acc(Nil, tree)
}
/** Is this pattern node a catch-all or type-test pattern? */
def isCatchCase(cdef: CaseDef)(using Context): Boolean = cdef match {
case CaseDef(Typed(Ident(nme.WILDCARD), tpt), EmptyTree, _) =>
isSimpleThrowable(tpt.tpe)
case CaseDef(Bind(_, Typed(Ident(nme.WILDCARD), tpt)), EmptyTree, _) =>
isSimpleThrowable(tpt.tpe)
case _ =>
isDefaultCase(cdef)
}
private def isSimpleThrowable(tp: Type)(using Context): Boolean = tp match {
case tp @ TypeRef(pre, _) =>
(pre == NoPrefix || pre.typeSymbol.isStatic) &&
(tp.symbol derivesFrom defn.ThrowableClass) && !tp.symbol.is(Trait)
case _ =>
false
}
/** The symbols defined locally in a statement list */
def localSyms(stats: List[Tree])(using Context): List[Symbol] =
if stats.isEmpty then Nil
else
val locals = new mutable.ListBuffer[Symbol]
for stat <- stats do
if stat.isDef && stat.symbol.exists then locals += stat.symbol
locals.toList
/** If `tree` is a DefTree, the symbol defined by it, otherwise NoSymbol */
def definedSym(tree: Tree)(using Context): Symbol =
if (tree.isDef) tree.symbol else NoSymbol
/** Going from child to parent, the path of tree nodes that starts
* with a definition of symbol `sym` and ends with `root`, or Nil
* if no such path exists.
* Pre: `sym` must have a position.
*/
def defPath(sym: Symbol, root: Tree)(using Context): List[Tree] = trace.onDebug(s"defpath($sym with position ${sym.span}, ${root.show})") {
require(sym.span.exists, sym)
object accum extends TreeAccumulator[List[Tree]] {
def apply(x: List[Tree], tree: Tree)(using Context): List[Tree] =
if (tree.span.contains(sym.span))
if (definedSym(tree) == sym) tree :: x
else {
val x1 = foldOver(x, tree)
if (x1 ne x) tree :: x1 else x1
}
else x
}
accum(Nil, root)
}
/** The top level classes in this tree, including only those module classes that
* are not a linked class of some other class in the result.
*/
def topLevelClasses(tree: Tree)(using Context): List[ClassSymbol] = tree match {
case PackageDef(_, stats) => stats.flatMap(topLevelClasses)
case tdef: TypeDef if tdef.symbol.isClass => tdef.symbol.asClass :: Nil
case _ => Nil
}
/** The tree containing only the top-level classes and objects matching either `cls` or its companion object */
def sliceTopLevel(tree: Tree, cls: ClassSymbol)(using Context): List[Tree] = tree match {
case PackageDef(pid, stats) =>
val slicedStats = stats.flatMap(sliceTopLevel(_, cls))
val isEffectivelyEmpty = slicedStats.forall(_.isInstanceOf[Import])
if isEffectivelyEmpty then Nil
else cpy.PackageDef(tree)(pid, slicedStats) :: Nil
case tdef: TypeDef =>
val sym = tdef.symbol
assert(sym.isClass || ctx.tolerateErrorsForBestEffort)
if (cls == sym || cls == sym.linkedClass) tdef :: Nil
else Nil
case vdef: ValDef =>
val sym = vdef.symbol
assert(sym.is(Module) || ctx.tolerateErrorsForBestEffort)
if (cls == sym.companionClass || cls == sym.moduleClass) vdef :: Nil
else Nil
case tree =>
tree :: Nil
}
/** The statement sequence that contains a definition of `sym`, or Nil
* if none was found.
* For a tree to be found, The symbol must have a position and its definition
* tree must be reachable from come tree stored in an enclosing context.
*/
def definingStats(sym: Symbol)(using Context): List[Tree] =
if (!sym.span.exists || (ctx eq NoContext) || (ctx.compilationUnit eq NoCompilationUnit)) Nil
else defPath(sym, ctx.compilationUnit.tpdTree) match {
case defn :: encl :: _ =>
def verify(stats: List[Tree]) =
if (stats exists (definedSym(_) == sym)) stats else Nil
encl match {
case Block(stats, _) => verify(stats)
case encl: Template => verify(encl.body)
case PackageDef(_, stats) => verify(stats)
case _ => Nil
}
case nil =>
Nil
}
/** If `tree` is an instance of `TupleN[...](e1, ..., eN)`, the arguments `e1, ..., eN`
* otherwise the empty list.
*/
def tupleArgs(tree: Tree)(using Context): List[Tree] = tree match {
case Block(Nil, expr) => tupleArgs(expr)
case Inlined(_, Nil, expr) => tupleArgs(expr)
case Apply(fn: NameTree, args)
if fn.name == nme.apply &&
fn.symbol.owner.is(Module) &&
defn.isTupleClass(fn.symbol.owner.companionClass) => args
case _ => Nil
}
/** The qualifier part of a Select or Ident.
* For an Ident, this is the `This` of the current class.
*/
def qualifier(tree: Tree)(using Context): Tree = tree match {
case Select(qual, _) => qual
case tree: Ident => desugarIdentPrefix(tree)
case _ => This(ctx.owner.enclosingClass.asClass)
}
/** Is this a (potentially applied) selection of a member of a structural type
* that is not a member of an underlying class or trait?
*/
def isStructuralTermSelectOrApply(tree: Tree)(using Context): Boolean = {
def isStructuralTermSelect(tree: Select) =
def hasRefinement(qualtpe: Type): Boolean = qualtpe.dealias match
case defn.FunctionTypeOfMethod(_) =>
false
case tp: MatchType =>
hasRefinement(tp.tryNormalize)
case RefinedType(parent, rname, rinfo) =>
rname == tree.name || hasRefinement(parent)
case tp: TypeProxy =>
hasRefinement(tp.superType)
case tp: AndType =>
hasRefinement(tp.tp1) || hasRefinement(tp.tp2)
case tp: OrType =>
hasRefinement(tp.tp1) || hasRefinement(tp.tp2)
case _ =>
false
!tree.symbol.exists
&& tree.isTerm
&& hasRefinement(tree.qualifier.tpe)
funPart(tree) match
case tree: Select =>
isStructuralTermSelect(tree)
case _ =>
false
}
/** Return a pair consisting of (supercall, rest)
*
* - supercall: the superclass call, excluding trait constr calls
*
* The supercall is always the first statement (if it exists)
*/
final def splitAtSuper(constrStats: List[Tree])(implicit ctx: Context): (List[Tree], List[Tree]) =
constrStats.toList match {
case (sc: Apply) :: rest if sc.symbol.isConstructor => (sc :: Nil, rest)
case (block @ Block(_, sc: Apply)) :: rest if sc.symbol.isConstructor => (block :: Nil, rest)
case stats => (Nil, stats)
}
/** Structural tree comparison (since == on trees is reference equality).
* For the moment, only Ident, Select, Literal, Apply and TypeApply are supported
*/
extension (t1: Tree) {
def === (t2: Tree)(using Context): Boolean = (t1, t2) match {
case (t1: Ident, t2: Ident) =>
t1.symbol == t2.symbol
case (t1 @ Select(q1, _), t2 @ Select(q2, _)) =>
t1.symbol == t2.symbol && q1 === q2
case (Literal(c1), Literal(c2)) =>
c1 == c2
case (Apply(f1, as1), Apply(f2, as2)) =>
f1 === f2 && as1.corresponds(as2)(_ === _)
case (TypeApply(f1, ts1), TypeApply(f2, ts2)) =>
f1 === f2 && ts1.tpes.corresponds(ts2.tpes)(_ =:= _)
case _ =>
false
}
def hash(using Context): Int =
t1.getClass.hashCode * 37 + {
t1 match {
case t1: Ident => t1.symbol.hashCode
case t1 @ Select(q1, _) => t1.symbol.hashCode * 41 + q1.hash
case Literal(c1) => c1.hashCode
case Apply(f1, as1) => as1.foldLeft(f1.hash)((h, arg) => h * 41 + arg.hash)
case TypeApply(f1, ts1) => ts1.foldLeft(f1.hash)((h, arg) => h * 41 + arg.tpe.hash)
case _ => t1.hashCode
}
}
}
def assertAllPositioned(tree: Tree)(using Context): Unit =
tree.foreachSubTree {
case t: WithoutTypeOrPos[?] =>
case t => assert(t.span.exists, i"$t")
}
object QuotedTypeOf {
/** Extracts the content of a quoted tree.
* The result can be the contents of a term or type quote, which
* will return a term or type tree respectively.
*/
def unapply(tree: tpd.Apply)(using Context): Option[tpd.Tree] =
if tree.symbol == defn.QuotedTypeModule_of then
// quoted.Type.of[](quotes)
val TypeApply(_, body :: _) = tree.fun: @unchecked
Some(body)
else None
}
/** Extractors for type splices */
object SplicedType {
/** Extracts the content of a spliced type tree.
* The result can be the contents of a type splice, which
* will return a type tree.
*/
def unapply(tree: tpd.Select)(using Context): Option[tpd.Tree] =
if tree.symbol.isTypeSplice then Some(tree.qualifier) else None
}
extension (tree: tpd.Quote)
/** Type of the quoted expression as seen from outside the quote */
def bodyType(using Context): Type =
val quoteType = tree.tpe // `Quotes ?=> Expr[T]` or `Quotes ?=> Type[T]`
val exprType = quoteType.argInfos.last // `Expr[T]` or `Type[T]`
exprType.argInfos.head // T
end extension
extension (tree: tpd.QuotePattern)
/** Type of the quoted pattern */
def bodyType(using Context): Type =
val quoteType = tree.tpe // `Expr[T]` or `Type[T]`
quoteType.argInfos.head // T
end extension
/** Extractor for not-null assertions.
* A not-null assertion for reference `x` has the form `x.$asInstanceOf$[x.type & T]`.
*/
object AssertNotNull :
def apply(tree: tpd.Tree, tpnn: Type)(using Context): tpd.Tree =
tree.select(defn.Any_typeCast).appliedToType(AndType(tree.tpe, tpnn))
def unapply(tree: tpd.TypeApply)(using Context): Option[tpd.Tree] = tree match
case TypeApply(Select(qual: RefTree, nme.asInstanceOfPM), arg :: Nil) =>
arg.tpe match
case AndType(ref, nn1) if qual.tpe eq ref =>
qual.tpe.widen match
case OrNull(nn2) if nn1 eq nn2 =>
Some(qual)
case _ => None
case _ => None
case _ => None
end AssertNotNull
object ConstantValue {
def unapply(tree: Tree)(using Context): Option[Any] =
tree match
case Typed(expr, _) => unapply(expr)
case Inlined(_, Nil, expr) => unapply(expr)
case Block(Nil, expr) => unapply(expr)
case _ =>
tree.tpe.widenTermRefExpr.dealias.normalized match
case ConstantType(Constant(x)) => Some(x)
case _ => None
}
}
object TreeInfo {
/** A purity level is represented as a bitset (expressed as an Int) */
class PurityLevel(val x: Int) extends AnyVal {
/** `this` contains the bits of `that` */
def >= (that: PurityLevel): Boolean = (x & that.x) == that.x
/** The intersection of the bits of `this` and `that` */
def min(that: PurityLevel): PurityLevel = new PurityLevel(x & that.x)
}
/** An expression is a stable path. Requires that expression is at least idempotent */
val Path: PurityLevel = new PurityLevel(4)
/** The expression has no side effects */
val Pure: PurityLevel = new PurityLevel(3)
/** Running the expression a second time has no side effects. Implied by `Pure`. */
val Idempotent: PurityLevel = new PurityLevel(1)
val Impure: PurityLevel = new PurityLevel(0)
/** A stable path that is evaluated without side effects */
val PurePath: PurityLevel = new PurityLevel(Pure.x | Path.x)
/** A stable path that is also idempotent */
val IdempotentPath: PurityLevel = new PurityLevel(Idempotent.x | Path.x)
}
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