Scala example source code file (TreeInfo.scala)
The TreeInfo.scala Scala example source code/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
* @author Martin Odersky
*/
package scala
package reflect
package internal
import Flags._
/** This class ...
*
* @author Martin Odersky
* @version 1.0
*/
abstract class TreeInfo {
val global: SymbolTable
import global._
import definitions.{ isTupleSymbol, isVarArgsList, isCastSymbol, ThrowableClass, TupleClass, uncheckedStableClass, isBlackboxMacroBundleType, isWhiteboxContextType }
/* Does not seem to be used. Not sure what it does anyway.
def isOwnerDefinition(tree: Tree): Boolean = tree match {
case PackageDef(_, _)
| ClassDef(_, _, _, _)
| ModuleDef(_, _, _)
| DefDef(_, _, _, _, _, _)
| Import(_, _) => true
case _ => false
}
*/
// def isDefinition(tree: Tree): Boolean = tree.isDef
/** Is tree a declaration or type definition?
*/
def isDeclarationOrTypeDef(tree: Tree): Boolean = tree match {
case x: ValOrDefDef => x.rhs eq EmptyTree
case _ => tree.isInstanceOf[TypeDef]
}
/** Is tree legal as a member definition of an interface?
*/
def isInterfaceMember(tree: Tree): Boolean = tree match {
case EmptyTree => true
case Import(_, _) => true
case TypeDef(_, _, _, _) => true
case DefDef(mods, _, _, _, _, __) => mods.isDeferred
case ValDef(mods, _, _, _) => mods.isDeferred
case _ => false
}
def isConstructorWithDefault(t: Tree) = t match {
case DefDef(_, nme.CONSTRUCTOR, _, vparamss, _, _) => mexists(vparamss)(_.mods.hasDefault)
case _ => false
}
/** Is tree a pure (i.e. non-side-effecting) definition?
*/
def isPureDef(tree: Tree): Boolean = tree match {
case EmptyTree
| ClassDef(_, _, _, _)
| TypeDef(_, _, _, _)
| Import(_, _)
| DefDef(_, _, _, _, _, _) =>
true
case ValDef(mods, _, _, rhs) =>
!mods.isMutable && isExprSafeToInline(rhs)
case _ =>
false
}
/** Is `tree` a path, defined as follows? (Spec: 3.1 Paths)
*
* - The empty path ε (which cannot be written explicitly in user programs).
* - C.this, where C references a class.
* - p.x where p is a path and x is a stable member of p.
* - C.super.x or C.super[M].x where C references a class
* and x references a stable member of the super class or designated parent class M of C.
*
* NOTE: Trees with errors are (mostly) excluded.
*
* Path ::= StableId | [id ‘.’] this
*
*/
def isPath(tree: Tree, allowVolatile: Boolean): Boolean =
tree match {
// Super is not technically a path.
// However, syntactically, it can only occur nested in a Select.
// This gives a nicer definition of isStableIdentifier that's equivalent to the spec's.
// must consider Literal(_) a path for typedSingletonTypeTree
case EmptyTree | Literal(_) => true
case This(_) | Super(_, _) => symOk(tree.symbol)
case _ => isStableIdentifier(tree, allowVolatile)
}
/** Is `tree` a stable identifier, a path which ends in an identifier?
*
* StableId ::= id
* | Path ‘.’ id
* | [id ’.’] ‘super’ [‘[’ id ‘]’] ‘.’ id
*/
def isStableIdentifier(tree: Tree, allowVolatile: Boolean): Boolean =
tree match {
case i @ Ident(_) => isStableIdent(i, allowVolatile)
case Select(qual, _) => isStableMemberOf(tree.symbol, qual, allowVolatile) && isPath(qual, allowVolatile)
case Apply(Select(free @ Ident(_), nme.apply), _) if free.symbol.name endsWith nme.REIFY_FREE_VALUE_SUFFIX =>
// see a detailed explanation of this trick in `GenSymbols.reifyFreeTerm`
free.symbol.hasStableFlag && isPath(free, allowVolatile)
case _ => false
}
private def symOk(sym: Symbol) = sym != null && !sym.isError && sym != NoSymbol
private def typeOk(tp: Type) = tp != null && ! tp.isError
/** Assuming `sym` is a member of `tree`, is it a "stable member"?
*
* Stable members are packages or members introduced
* by object definitions or by value definitions of non-volatile types (§3.6).
*/
def isStableMemberOf(sym: Symbol, tree: Tree, allowVolatile: Boolean): Boolean = (
symOk(sym) && (!sym.isTerm || (sym.isStable && (allowVolatile || !sym.hasVolatileType))) &&
typeOk(tree.tpe) && (allowVolatile || !hasVolatileType(tree)) && !definitions.isByNameParamType(tree.tpe)
)
private def isStableIdent(tree: Ident, allowVolatile: Boolean): Boolean = (
symOk(tree.symbol)
&& tree.symbol.isStable
&& !definitions.isByNameParamType(tree.tpe)
&& (allowVolatile || !tree.symbol.hasVolatileType) // TODO SPEC: not required by spec
)
/** Is `tree`'s type volatile? (Ignored if its symbol has the @uncheckedStable annotation.)
*/
def hasVolatileType(tree: Tree): Boolean =
symOk(tree.symbol) && tree.tpe.isVolatile && !tree.symbol.hasAnnotation(uncheckedStableClass)
/** Is `tree` either a non-volatile type,
* or a path that does not include any of:
* - a reference to a mutable variable/field
* - a reference to a by-name parameter
* - a member selection on a volatile type (Spec: 3.6 Volatile Types)?
*
* Such a tree is a suitable target for type selection.
*/
def admitsTypeSelection(tree: Tree): Boolean = isPath(tree, allowVolatile = false)
/** Is `tree` admissible as a stable identifier pattern (8.1.5 Stable Identifier Patterns)?
*
* We disregard volatility, as it's irrelevant in patterns (SI-6815)
*/
def isStableIdentifierPattern(tree: Tree): Boolean = isStableIdentifier(tree, allowVolatile = true)
// TODO SI-5304 tighten this up so we don't elide side effect in module loads
def isQualifierSafeToElide(tree: Tree): Boolean = isExprSafeToInline(tree)
/** Is tree an expression which can be inlined without affecting program semantics?
*
* Note that this is not called "isExprPure" since purity (lack of side-effects)
* is not the litmus test. References to modules and lazy vals are 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 safe to inline
* because the expression result from evaluating them is always the same.
*/
def isExprSafeToInline(tree: Tree): Boolean = tree match {
case EmptyTree
| This(_)
| Super(_, _)
| Literal(_) =>
true
case Ident(_) =>
tree.symbol.isStable
// this case is mostly to allow expressions like -5 and +7, but any
// member of an anyval should be safely pure
case Select(Literal(const), name) =>
const.isAnyVal && (const.tpe.member(name) != NoSymbol)
case Select(qual, _) =>
tree.symbol.isStable && isExprSafeToInline(qual)
case TypeApply(fn, _) =>
isExprSafeToInline(fn)
case Apply(Select(free @ Ident(_), nme.apply), _) if free.symbol.name endsWith nme.REIFY_FREE_VALUE_SUFFIX =>
// see a detailed explanation of this trick in `GenSymbols.reifyFreeTerm`
free.symbol.hasStableFlag && isExprSafeToInline(free)
case Apply(fn, List()) =>
// Note: After uncurry, field accesses are represented as Apply(getter, Nil),
// so an Apply can also be pure.
// However, before typing, applications of nullary functional values are also
// Apply(function, Nil) trees. To prevent them from being treated as pure,
// we check that the callee is a method.
// The callee might also be a Block, which has a null symbol, so we guard against that (SI-7185)
fn.symbol != null && fn.symbol.isMethod && !fn.symbol.isLazy && isExprSafeToInline(fn)
case Typed(expr, _) =>
isExprSafeToInline(expr)
case Block(stats, expr) =>
(stats forall isPureDef) && isExprSafeToInline(expr)
case _ =>
false
}
/** As if the name of the method didn't give it away,
* this logic is designed around issuing helpful
* warnings and minimizing spurious ones. That means
* don't reuse it for important matters like inlining
* decisions.
*/
def isPureExprForWarningPurposes(tree: Tree): Boolean = tree match {
case Typed(expr, _) => isPureExprForWarningPurposes(expr)
case EmptyTree | Literal(Constant(())) => false
case _ =>
def isWarnableRefTree = tree match {
case t: RefTree => isExprSafeToInline(t.qualifier) && t.symbol != null && t.symbol.isAccessor
case _ => false
}
def isWarnableSymbol = {
val sym = tree.symbol
(sym == null) || !(sym.isModule || sym.isLazy || definitions.isByNameParamType(sym.tpe_*)) || {
debuglog("'Pure' but side-effecting expression in statement position: " + tree)
false
}
}
( !tree.isErrorTyped
&& (isExprSafeToInline(tree) || isWarnableRefTree)
&& isWarnableSymbol
)
}
def mapMethodParamsAndArgs[R](params: List[Symbol], args: List[Tree])(f: (Symbol, Tree) => R): List[R] = {
val b = List.newBuilder[R]
foreachMethodParamAndArg(params, args)((param, arg) => b += f(param, arg))
b.result()
}
def foreachMethodParamAndArg(params: List[Symbol], args: List[Tree])(f: (Symbol, Tree) => Unit): Boolean = {
val plen = params.length
val alen = args.length
def fail() = {
global.devWarning(
s"""|Mismatch trying to zip method parameters and argument list:
| params = $params
| args = $args""".stripMargin)
false
}
if (plen == alen) foreach2(params, args)(f)
else if (params.isEmpty) return fail()
else if (isVarArgsList(params)) {
val plenInit = plen - 1
if (alen == plenInit) {
if (alen == 0) Nil // avoid calling mismatched zip
else foreach2(params.init, args)(f)
}
else if (alen < plenInit) return fail()
else {
foreach2(params.init, args take plenInit)(f)
val remainingArgs = args drop plenInit
foreach2(List.fill(remainingArgs.size)(params.last), remainingArgs)(f)
}
}
else return fail()
true
}
/** Is symbol potentially a getter of a variable?
*/
def mayBeVarGetter(sym: Symbol): Boolean = sym.info match {
case NullaryMethodType(_) => sym.owner.isClass && !sym.isStable
case PolyType(_, NullaryMethodType(_)) => sym.owner.isClass && !sym.isStable
case mt @ MethodType(_, _) => mt.isImplicit && sym.owner.isClass && !sym.isStable
case _ => false
}
/** Is tree a mutable variable, or the getter of a mutable field?
*/
def isVariableOrGetter(tree: Tree) = {
def sym = tree.symbol
def isVar = sym.isVariable
def isGetter = mayBeVarGetter(sym) && sym.owner.info.member(sym.setterName) != NoSymbol
tree match {
case Ident(_) => isVar
case Select(_, _) => isVar || isGetter
case Applied(Select(qual, nme.apply), _, _) => qual.tpe.member(nme.update) != NoSymbol
case _ => false
}
}
def isDefaultGetter(tree: Tree) = {
tree.symbol != null && tree.symbol.isDefaultGetter
}
/** Is tree a self constructor call this(...)? I.e. a call to a constructor of the
* same object?
*/
def isSelfConstrCall(tree: Tree): Boolean = dissectApplied(tree).core match {
case Ident(nme.CONSTRUCTOR) => true
case Select(This(_), nme.CONSTRUCTOR) => true
case _ => false
}
/** Is tree a super constructor call?
*/
def isSuperConstrCall(tree: Tree): Boolean = dissectApplied(tree).core match {
case Select(Super(_, _), nme.CONSTRUCTOR) => true
case _ => false
}
/**
* Named arguments can transform a constructor call into a block, e.g.
* <init>(b = foo, a = bar)
* is transformed to
* { val x$1 = foo
* val x$2 = bar
* <init>(x$2, x$1)
* }
*/
def stripNamedApplyBlock(tree: Tree) = tree match {
case Block(stats, expr) if stats.forall(_.isInstanceOf[ValDef]) =>
expr
case _ =>
tree
}
/** Strips layers of `.asInstanceOf[T]` / `_.$asInstanceOf[T]()` from an expression */
def stripCast(tree: Tree): Tree = tree match {
case TypeApply(sel @ Select(inner, _), _) if isCastSymbol(sel.symbol) =>
stripCast(inner)
case Apply(TypeApply(sel @ Select(inner, _), _), Nil) if isCastSymbol(sel.symbol) =>
stripCast(inner)
case t =>
t
}
object StripCast {
def unapply(tree: Tree): Some[Tree] = Some(stripCast(tree))
}
/** Is tree a self or super constructor call? */
def isSelfOrSuperConstrCall(tree: Tree) = {
// stripNamedApply for SI-3584: adaptToImplicitMethod in Typers creates a special context
// for implicit search in constructor calls, adaptToImplicitMethod(isSelfOrConstrCall)
val tree1 = stripNamedApplyBlock(tree)
isSelfConstrCall(tree1) || isSuperConstrCall(tree1)
}
/**
* Does this tree represent an irrefutable pattern match
* in the position `for { <tree> <- expr }` based only
* on information at the `parser` phase? To qualify, there
* may be no subtree that will be interpreted as a
* Stable Identifier Pattern, nor any type tests, even
* on TupleN. See SI-6968.
*
* For instance:
*
* {{{
* (foo @ (bar @ _)) = 0
* }}}
*
* is a not a variable pattern; if only binds names.
*
* The following are not variable patterns.
*
* {{{
* `bar`
* Bar
* (a, b)
* _: T
* }}}
*
* If the pattern is a simple identifier, it is always
* a variable pattern. For example, the following
* introduce new bindings:
*
* {{{
* for { X <- xs } yield X
* for { `backquoted` <- xs } yield `backquoted`
* }}}
*
* Note that this differs from a case clause:
*
* {{{
* object X
* scrut match {
* case X => // case _ if scrut == X
* }
* }}}
*
* Background: [[https://groups.google.com/d/msg/scala-internals/qwa_XOw_7Ks/IktkeTBYqg0J]]
*
*/
def isVarPatternDeep(tree: Tree): Boolean = {
def isVarPatternDeep0(tree: Tree): Boolean = {
tree match {
case Bind(name, pat) => isVarPatternDeep0(pat)
case Ident(name) => isVarPattern(tree)
case _ => false
}
}
tree match {
case Ident(name) => true
case _ => isVarPatternDeep0(tree)
}
}
/** Is tree a variable pattern? */
def isVarPattern(pat: Tree): Boolean = pat match {
case x: Ident => !x.isBackquoted && nme.isVariableName(x.name)
case _ => false
}
/** Does the tree have a structure similar to typechecked trees? */
private[internal] def detectTypecheckedTree(tree: Tree) =
tree.hasExistingSymbol || tree.exists {
case dd: DefDef => dd.mods.hasAccessorFlag || dd.mods.isSynthetic // for untypechecked trees
case md: MemberDef => md.hasExistingSymbol
case _ => false
}
/** Recover template body to parsed state */
private[internal] def untypecheckedTemplBody(templ: Template) =
untypecheckedTreeBody(templ, templ.body)
/** Recover block body to parsed state */
private[internal] def untypecheckedBlockBody(block: Block) =
untypecheckedTreeBody(block, block.stats)
/** Recover tree body to parsed state */
private[internal] def untypecheckedTreeBody(tree: Tree, tbody: List[Tree]) = {
def filterBody(body: List[Tree]) = body filter {
case _: ValDef | _: TypeDef => true
// keep valdef or getter for val/var
case dd: DefDef if dd.mods.hasAccessorFlag => !nme.isSetterName(dd.name) && !tbody.exists {
case vd: ValDef => dd.name == vd.name.dropLocal
case _ => false
}
case md: MemberDef => !md.mods.isSynthetic
case tree => true
}
def lazyValDefRhs(body: Tree) =
body match {
case Block(List(Assign(_, rhs)), _) => rhs
case _ => body
}
def recoverBody(body: List[Tree]) = body map {
case vd @ ValDef(vmods, vname, _, vrhs) if nme.isLocalName(vname) =>
tbody find {
case dd: DefDef => dd.name == vname.dropLocal
case _ => false
} map { dd =>
val DefDef(dmods, dname, _, _, _, drhs) = dd
// get access flags from DefDef
val vdMods = (vmods &~ Flags.AccessFlags) | (dmods & Flags.AccessFlags).flags
// for most cases lazy body should be taken from accessor DefDef
val vdRhs = if (vmods.isLazy) lazyValDefRhs(drhs) else vrhs
copyValDef(vd)(mods = vdMods, name = dname, rhs = vdRhs)
} getOrElse (vd)
// for abstract and some lazy val/vars
case dd @ DefDef(mods, name, _, _, tpt, rhs) if mods.hasAccessorFlag =>
// transform getter mods to field
val vdMods = (if (!mods.hasStableFlag) mods | Flags.MUTABLE else mods &~ Flags.STABLE) &~ Flags.ACCESSOR
ValDef(vdMods, name, tpt, rhs)
case tr => tr
}
if (detectTypecheckedTree(tree)) {
recoverBody(filterBody(tbody))
} else tbody
}
/** The first constructor definitions in `stats` */
def firstConstructor(stats: List[Tree]): Tree = stats find {
case x: DefDef => nme.isConstructorName(x.name)
case _ => false
} getOrElse EmptyTree
/** The arguments to the first constructor in `stats`. */
def firstConstructorArgs(stats: List[Tree]): List[Tree] = firstConstructor(stats) match {
case DefDef(_, _, _, args :: _, _, _) => args
case _ => Nil
}
/** The value definitions marked PRESUPER in this statement sequence */
def preSuperFields(stats: List[Tree]): List[ValDef] =
stats collect { case vd: ValDef if isEarlyValDef(vd) => vd }
def hasUntypedPreSuperFields(stats: List[Tree]): Boolean =
preSuperFields(stats) exists (_.tpt.isEmpty)
def isEarlyDef(tree: Tree) = tree match {
case TypeDef(mods, _, _, _) => mods hasFlag PRESUPER
case ValDef(mods, _, _, _) => mods hasFlag PRESUPER
case _ => false
}
def isEarlyValDef(tree: Tree) = tree match {
case ValDef(mods, _, _, _) => mods hasFlag PRESUPER
case _ => false
}
/** Is tpt a vararg type of the form T* ? */
def isRepeatedParamType(tpt: Tree) = tpt match {
case TypeTree() => definitions.isRepeatedParamType(tpt.tpe)
case AppliedTypeTree(Select(_, tpnme.REPEATED_PARAM_CLASS_NAME), _) => true
case AppliedTypeTree(Select(_, tpnme.JAVA_REPEATED_PARAM_CLASS_NAME), _) => true
case _ => false
}
/** The parameter ValDefs of a method definition that have vararg types of the form T*
*/
def repeatedParams(tree: Tree): List[ValDef] = tree match {
case DefDef(_, _, _, vparamss, _, _) => vparamss.flatten filter (vd => isRepeatedParamType(vd.tpt))
case _ => Nil
}
/** Is tpt a by-name parameter type of the form => T? */
def isByNameParamType(tpt: Tree) = tpt match {
case TypeTree() => definitions.isByNameParamType(tpt.tpe)
case AppliedTypeTree(Select(_, tpnme.BYNAME_PARAM_CLASS_NAME), _) => true
case _ => false
}
/** Translates an Assign(_, _) node to AssignOrNamedArg(_, _) if
* the lhs is a simple ident. Otherwise returns unchanged.
*/
def assignmentToMaybeNamedArg(tree: Tree) = tree match {
case t @ Assign(id: Ident, rhs) => atPos(t.pos)(AssignOrNamedArg(id, rhs))
case t => t
}
/** Is name a left-associative operator? */
def isLeftAssoc(operator: Name) = operator.nonEmpty && (operator.endChar != ':')
/** a Match(Typed(_, tpt), _) must be translated into a switch if isSwitchAnnotation(tpt.tpe) */
def isSwitchAnnotation(tpe: Type) = tpe hasAnnotation definitions.SwitchClass
/** can this type be a type pattern */
def mayBeTypePat(tree: Tree): Boolean = tree match {
case CompoundTypeTree(Template(tps, _, Nil)) => tps exists mayBeTypePat
case Annotated(_, tp) => mayBeTypePat(tp)
case AppliedTypeTree(constr, args) => mayBeTypePat(constr) || args.exists(_.isInstanceOf[Bind])
case SelectFromTypeTree(tp, _) => mayBeTypePat(tp)
case _ => false
}
/** Is this argument node of the form <expr> : _* ?
*/
def isWildcardStarArg(tree: Tree): Boolean = tree match {
case WildcardStarArg(_) => true
case _ => false
}
object WildcardStarArg {
def unapply(tree: Tree): Option[Tree] = tree match {
case Typed(expr, Ident(tpnme.WILDCARD_STAR)) => Some(expr)
case _ => None
}
}
/** If this tree has type parameters, those. Otherwise Nil.
*/
def typeParameters(tree: Tree): List[TypeDef] = tree match {
case DefDef(_, _, tparams, _, _, _) => tparams
case ClassDef(_, _, tparams, _) => tparams
case TypeDef(_, _, tparams, _) => tparams
case _ => Nil
}
/** Does this argument list end with an argument of the form <expr> : _* ? */
def isWildcardStarArgList(trees: List[Tree]) =
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
}
/** Is the argument a wildcard star type of the form `_*`?
*/
def isWildcardStarType(tree: Tree): Boolean = tree match {
case Ident(tpnme.WILDCARD_STAR) => true
case _ => false
}
/** Is this pattern node a catch-all (wildcard or variable) pattern? */
def isDefaultCase(cdef: CaseDef) = cdef match {
case CaseDef(pat, EmptyTree, _) => isWildcardArg(pat)
case _ => false
}
private def hasNoSymbol(t: Tree) = t.symbol == null || t.symbol == NoSymbol
/** Is this pattern node a synthetic catch-all case, added during PartialFuction synthesis before we know
* whether the user provided cases are exhaustive. */
def isSyntheticDefaultCase(cdef: CaseDef) = cdef match {
case CaseDef(Bind(nme.DEFAULT_CASE, _), EmptyTree, _) => true
case _ => false
}
/** Does this CaseDef catch Throwable? */
def catchesThrowable(cdef: CaseDef) = (
cdef.guard.isEmpty && (unbind(cdef.pat) match {
case Ident(nme.WILDCARD) => true
case i@Ident(name) => hasNoSymbol(i)
case _ => false
})
)
/** Is this CaseDef synthetically generated, e.g. by `MatchTranslation.translateTry`? */
def isSyntheticCase(cdef: CaseDef) = cdef.pat.exists {
case dt: DefTree => dt.symbol.isSynthetic
case _ => false
}
/** Is this pattern node a catch-all or type-test pattern? */
def isCatchCase(cdef: CaseDef) = 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): Boolean = tp match {
case TypeRef(pre, sym, args) =>
(pre == NoPrefix || pre.widen.typeSymbol.isStatic) &&
(sym isNonBottomSubClass ThrowableClass) && /* bq */ !sym.isTrait
case _ =>
false
}
/* If we have run-time types, and these are used for pattern matching,
we should replace this by something like:
tp match {
case TypeRef(pre, sym, args) =>
args.isEmpty && (sym.isTopLevel || isSimple(pre))
case NoPrefix =>
true
case _ =>
false
}
*/
/** Is this case guarded? */
def isGuardedCase(cdef: CaseDef) = cdef.guard != EmptyTree
/** Is this pattern node a sequence-valued pattern? */
def isSequenceValued(tree: Tree): Boolean = unbind(tree) match {
case Alternative(ts) => ts exists isSequenceValued
case ArrayValue(_, _) | Star(_) => true
case _ => false
}
/** The underlying pattern ignoring any bindings */
def unbind(x: Tree): Tree = x match {
case Bind(_, y) => unbind(y)
case y => y
}
/** Is this tree a Star(_) after removing bindings? */
def isStar(x: Tree) = unbind(x) match {
case Star(_) => true
case _ => false
}
/**
* {{{
* //------------------------ => effectivePatternArity(args)
* case Extractor(a) => 1
* case Extractor(a, b) => 2
* case Extractor((a, b)) => 2
* case Extractor(a @ (b, c)) => 2
* }}}
*/
def effectivePatternArity(args: List[Tree]): Int = flattenedPatternArgs(args).length
def flattenedPatternArgs(args: List[Tree]): List[Tree] = args map unbind match {
case build.SyntacticTuple(xs) :: Nil => xs
case xs => xs
}
// used in the symbols for labeldefs and valdefs emitted by the pattern matcher
// tailcalls, cps,... use this flag combination to detect translated matches
// TODO: move to Flags
final val SYNTH_CASE_FLAGS = CASE | SYNTHETIC
def isSynthCaseSymbol(sym: Symbol) = sym hasAllFlags SYNTH_CASE_FLAGS
def hasSynthCaseSymbol(t: Tree) = t.symbol != null && isSynthCaseSymbol(t.symbol)
def isTraitRef(tree: Tree): Boolean = {
val sym = if (tree.tpe != null) tree.tpe.typeSymbol else null
((sym ne null) && sym.initialize.isTrait)
}
/** Applications in Scala can have one of the following shapes:
*
* 1) naked core: Ident(_) or Select(_, _) or basically anything else
* 2) naked core with targs: TypeApply(core, targs) or AppliedTypeTree(core, targs)
* 3) apply or several applies wrapping a core: Apply(core, _), or Apply(Apply(core, _), _), etc
*
* This class provides different ways to decompose applications and simplifies their analysis.
*
* ***Examples***
* (TypeApply in the examples can be replaced with AppliedTypeTree)
*
* Ident(foo):
* * callee = Ident(foo)
* * core = Ident(foo)
* * targs = Nil
* * argss = Nil
*
* TypeApply(foo, List(targ1, targ2...))
* * callee = TypeApply(foo, List(targ1, targ2...))
* * core = foo
* * targs = List(targ1, targ2...)
* * argss = Nil
*
* Apply(foo, List(arg1, arg2...))
* * callee = foo
* * core = foo
* * targs = Nil
* * argss = List(List(arg1, arg2...))
*
* Apply(Apply(foo, List(arg21, arg22, ...)), List(arg11, arg12...))
* * callee = foo
* * core = foo
* * targs = Nil
* * argss = List(List(arg11, arg12...), List(arg21, arg22, ...))
*
* Apply(Apply(TypeApply(foo, List(targs1, targs2, ...)), List(arg21, arg22, ...)), List(arg11, arg12...))
* * callee = TypeApply(foo, List(targs1, targs2, ...))
* * core = foo
* * targs = Nil
* * argss = List(List(arg11, arg12...), List(arg21, arg22, ...))
*/
class Applied(val tree: Tree) {
/** The tree stripped of the possibly nested applications.
* The original tree if it's not an application.
*/
def callee: Tree = {
def loop(tree: Tree): Tree = tree match {
case Apply(fn, _) => loop(fn)
case tree => tree
}
loop(tree)
}
/** The `callee` unwrapped from type applications.
* The original `callee` if it's not a type application.
*/
def core: Tree = callee match {
case TypeApply(fn, _) => fn
case AppliedTypeTree(fn, _) => fn
case tree => tree
}
/** The type arguments of the `callee`.
* `Nil` if the `callee` is not a type application.
*/
def targs: List[Tree] = callee match {
case TypeApply(_, args) => args
case AppliedTypeTree(_, args) => args
case _ => Nil
}
/** (Possibly multiple lists of) value arguments of an application.
* `Nil` if the `callee` is not an application.
*/
def argss: List[List[Tree]] = {
def loop(tree: Tree): List[List[Tree]] = tree match {
case Apply(fn, args) => loop(fn) :+ args
case _ => Nil
}
loop(tree)
}
}
/** Returns a wrapper that knows how to destructure and analyze applications.
*/
def dissectApplied(tree: Tree) = new Applied(tree)
/** Destructures applications into important subparts described in `Applied` class,
* namely into: core, targs and argss (in the specified order).
*
* Trees which are not applications are also accepted. Their callee and core will
* be equal to the input, while targs and argss will be Nil.
*
* The provided extractors don't expose all the API of the `Applied` class.
* For advanced use, call `dissectApplied` explicitly and use its methods instead of pattern matching.
*/
object Applied {
def apply(tree: Tree): Applied = new Applied(tree)
def unapply(applied: Applied): Option[(Tree, List[Tree], List[List[Tree]])] =
Some((applied.core, applied.targs, applied.argss))
def unapply(tree: Tree): Option[(Tree, List[Tree], List[List[Tree]])] =
unapply(dissectApplied(tree))
}
/** Does list of trees start with a definition of
* a class of module with given name (ignoring imports)
*/
def firstDefinesClassOrObject(trees: List[Tree], name: Name): Boolean = trees match {
case Import(_, _) :: xs => firstDefinesClassOrObject(xs, name)
case Annotated(_, tree1) :: _ => firstDefinesClassOrObject(List(tree1), name)
case ModuleDef(_, `name`, _) :: _ => true
case ClassDef(_, `name`, _, _) :: _ => true
case _ => false
}
/** Locates the synthetic Apply node corresponding to an extractor's call to
* unapply (unwrapping nested Applies) and returns the fun part of that Apply.
*/
object Unapplied {
// Duplicated with `spliceApply`
def unapply(tree: Tree): Option[Tree] = tree match {
// SI-7868 Admit Select() to account for numeric widening, e.g. <unappplySelector>.toInt
case Apply(fun, (Ident(nme.SELECTOR_DUMMY)| Select(Ident(nme.SELECTOR_DUMMY), _)) :: Nil)
=> Some(fun)
case Apply(fun, _) => unapply(fun)
case _ => None
}
}
/** Is this file the body of a compilation unit which should not
* have Predef imported?
*/
def noPredefImportForUnit(body: Tree) = {
// Top-level definition whose leading imports include Predef.
def isLeadingPredefImport(defn: Tree): Boolean = defn match {
case PackageDef(_, defs1) => defs1 exists isLeadingPredefImport
case Import(expr, _) => isReferenceToPredef(expr)
case _ => false
}
// Compilation unit is class or object 'name' in package 'scala'
def isUnitInScala(tree: Tree, name: Name) = tree match {
case PackageDef(Ident(nme.scala_), defs) => firstDefinesClassOrObject(defs, name)
case _ => false
}
isUnitInScala(body, nme.Predef) || isLeadingPredefImport(body)
}
def isAbsTypeDef(tree: Tree) = tree match {
case TypeDef(_, _, _, TypeBoundsTree(_, _)) => true
case TypeDef(_, _, _, rhs) => rhs.tpe.isInstanceOf[TypeBounds]
case _ => false
}
def isAliasTypeDef(tree: Tree) = tree match {
case TypeDef(_, _, _, _) => !isAbsTypeDef(tree)
case _ => false
}
/** Some handy extractors for spotting trees through the
* the haze of irrelevant braces: i.e. Block(Nil, SomeTree)
* should not keep us from seeing SomeTree.
*/
abstract class SeeThroughBlocks[T] {
protected def unapplyImpl(x: Tree): T
def unapply(x: Tree): T = x match {
case Block(Nil, expr) => unapply(expr)
case _ => unapplyImpl(x)
}
}
object IsTrue extends SeeThroughBlocks[Boolean] {
protected def unapplyImpl(x: Tree): Boolean = x match {
case Literal(Constant(true)) => true
case _ => false
}
}
object IsFalse extends SeeThroughBlocks[Boolean] {
protected def unapplyImpl(x: Tree): Boolean = x match {
case Literal(Constant(false)) => true
case _ => false
}
}
def isApplyDynamicName(name: Name) = (name == nme.updateDynamic) || (name == nme.selectDynamic) || (name == nme.applyDynamic) || (name == nme.applyDynamicNamed)
class DynamicApplicationExtractor(nameTest: Name => Boolean) {
def unapply(tree: Tree) = tree match {
case Apply(TypeApply(Select(qual, oper), _), List(Literal(Constant(name)))) if nameTest(oper) => Some((qual, name))
case Apply(Select(qual, oper), List(Literal(Constant(name)))) if nameTest(oper) => Some((qual, name))
case Apply(Ident(oper), List(Literal(Constant(name)))) if nameTest(oper) => Some((EmptyTree, name))
case _ => None
}
}
object DynamicUpdate extends DynamicApplicationExtractor(_ == nme.updateDynamic)
object DynamicApplication extends DynamicApplicationExtractor(isApplyDynamicName)
object DynamicApplicationNamed extends DynamicApplicationExtractor(_ == nme.applyDynamicNamed)
object MacroImplReference {
private def refPart(tree: Tree): Tree = tree match {
case TypeApply(fun, _) => refPart(fun)
case ref: RefTree => ref
case _ => EmptyTree
}
def unapply(tree: Tree) = refPart(tree) match {
case ref: RefTree => {
val qual = ref.qualifier
val isBundle = definitions.isMacroBundleType(qual.tpe)
val isBlackbox =
if (isBundle) isBlackboxMacroBundleType(qual.tpe)
else ref.symbol.paramss match {
case (c :: Nil) :: _ if isWhiteboxContextType(c.info) => false
case _ => true
}
val owner =
if (isBundle) qual.tpe.typeSymbol
else {
val qualSym = if (qual.hasSymbolField) qual.symbol else NoSymbol
if (qualSym.isModule) qualSym.moduleClass else qualSym
}
Some((isBundle, isBlackbox, owner, ref.symbol, dissectApplied(tree).targs))
}
case _ => None
}
}
def isNullaryInvocation(tree: Tree): Boolean =
tree.symbol != null && tree.symbol.isMethod && (tree match {
case TypeApply(fun, _) => isNullaryInvocation(fun)
case tree: RefTree => true
case _ => false
})
def isMacroApplication(tree: Tree): Boolean = !tree.isDef && {
val sym = tree.symbol
sym != null && sym.isTermMacro && !sym.isErroneous
}
def isMacroApplicationOrBlock(tree: Tree): Boolean = tree match {
case Block(_, expr) => isMacroApplicationOrBlock(expr)
case tree => isMacroApplication(tree)
}
}
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