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/* ____ ____ ____ ____ ______ *\
** / __// __ \/ __// __ \/ ____/ SOcos COmpiles Scala **
** __\_ \/ /_/ / /__/ /_/ /\_ \ (c) 2002, LAMP/EPFL **
** /_____/\____/\___/\____/____/ **
\* */
// $Id$
package scalac.transformer;
import java.util.Map;
import java.util.HashMap;
import java.util.Iterator;
import scalac.Global;
import scalac.Phase;
import scalac.PhaseDescriptor;
import scalac.Unit;
import scalac.symtab.Definitions;
import scalac.symtab.Scope;
import scalac.symtab.Symbol;
import scalac.symtab.Type;
import scalac.atree.AConstant;
import scalac.ast.Transformer;
import scalac.ast.GenTransformer;
import scalac.ast.Tree;
import scalac.backend.Primitives;
import scalac.util.Name;
import scalac.util.Names;
import scalac.util.Debug;
/**
* Turn types into values by applying the following transformations:
*
* - For all type member T of all classes, add an accessor method
* T$type returnining the type as a value (the accessor is abstract
* if the type member is abstract).
*
* - For all polymorphic methods/constructors, add a value parameter
* for each type parameter.
*
* - Add a method getType to every class, to obtain its type as a
* value.
*
* - Transform all type expressions into value expressions: type
* application is turned into value application, type selection into
* value selection, and so on.
*
* @author Michel Schinz
* @version 1.0
*/
public class TypesAsValuesPhase extends Phase {
private final TV_Transformer transformer;
private static final HashMap/*<Symbol,Map<Symbol,Symbol>>*/ membersToAdd =
new HashMap();
private static final HashMap/*<Symbol,Map<Symbol,Symbol>>*/ paramsToAdd =
new HashMap();
private static final HashMap/*<Symbol,Symbol>*/ accessors =
new HashMap();
private final Definitions defs = global.definitions;
private final Primitives prims = global.primitives;
private final Type typeType = defs.TYPE_TYPE();
private final Type.MethodType typeAccessorType =
new Type.MethodType(new Symbol[]{}, typeType);
private final Symbol singleTypeClass = defs.SINGLETYPE_CLASS;
private final Symbol ARRAY_CONSTRUCTOR =
defs.ARRAY_CLASS.primaryConstructor();
private final Map/*<Symbol, Symbol>*/ basicTypes;
public TypesAsValuesPhase(Global global, PhaseDescriptor descriptor) {
super(global, descriptor);
transformer = new TV_Transformer(global);
basicTypes = new HashMap();
basicTypes.put(defs.DOUBLE_CLASS, defs.RTT_DOUBLE());
basicTypes.put(defs.FLOAT_CLASS, defs.RTT_FLOAT());
basicTypes.put(defs.LONG_CLASS, defs.RTT_LONG());
basicTypes.put(defs.INT_CLASS, defs.RTT_INT());
basicTypes.put(defs.SHORT_CLASS, defs.RTT_SHORT());
basicTypes.put(defs.CHAR_CLASS, defs.RTT_CHAR());
basicTypes.put(defs.BYTE_CLASS, defs.RTT_BYTE());
basicTypes.put(defs.BOOLEAN_CLASS, defs.RTT_BOOLEAN());
}
/**
* Return a map associating symbols for type accessors to the
* symbol of their type.
*/
private HashMap typeAccessors(Symbol classSym) {
HashMap/*<Symbol, Symbol>*/ newSymbols =
(HashMap)membersToAdd.get(classSym);
if (newSymbols == null) {
newSymbols = new HashMap();
Scope.SymbolIterator membersIt = classSym.members().iterator(true);
while (membersIt.hasNext()) {
Symbol member = membersIt.next();
if (member.isType() /*&& !member.isClass()*/) {
Symbol typeAccessorSym = getAccessorSymbol(member);
newSymbols.put(member, typeAccessorSym);
}
}
membersToAdd.put(classSym, newSymbols);
}
return newSymbols;
}
private HashMap typeParams(Symbol funSym) {
HashMap newSymbols = (HashMap)paramsToAdd.get(funSym);
if (newSymbols == null) {
Symbol[] tparams = funSym.typeParams();
assert tparams.length > 0;
newSymbols = new HashMap();
for (int i = 0; i < tparams.length; ++i) {
Symbol param = tparams[i];
Symbol valueSym = getAccessorSymbol(param);
newSymbols.put(param, valueSym);
}
paramsToAdd.put(funSym, newSymbols);
}
return newSymbols;
}
/**
* Return the symbol of the accessor for the given type symbol.
*/
private Symbol getAccessorSymbol(Symbol typeSym) {
assert typeSym.isType();
Symbol accessorSym = (Symbol)accessors.get(typeSym);
if (accessorSym == null) {
accessorSym = typeSym.owner().newVariable(typeSym.pos,
typeSym.flags,
Names.TYPE(typeSym));
accessorSym.setInfo(typeSym.owner().isClass()
? typeAccessorType
: typeType);
accessors.put(typeSym, accessorSym);
}
return accessorSym;
}
public Type transformInfo(Symbol symbol, Type type) {
if (symbol.isClass()) {
// Class:
// - add an accessor per type member.
HashMap newSymbols = typeAccessors(symbol);
if (newSymbols.isEmpty())
return type;
else {
Scope newMembers = new Scope(symbol.members());
Iterator newSymbolsIt = newSymbols.values().iterator();
while (newSymbolsIt.hasNext())
newMembers.enterOrOverload((Symbol)newSymbolsIt.next());
return Type.compoundType(type.parents(), newMembers, symbol);
}
} else if (type.typeParams().length > 0 && !isPrimitive(symbol)) {
// Polymorphic method/constructor:
// - add a value parameter for every type parameter.
switch (type) {
case PolyType(Symbol[] tparams, // :
Type.MethodType(Symbol[] vparams, Type result)):
HashMap newVParams = typeParams(symbol);
Symbol[] allVParams =
new Symbol[newVParams.size() + vparams.length];
for (int i = 0; i < tparams.length; ++i)
allVParams[i] = (Symbol)newVParams.get(tparams[i]);
System.arraycopy(vparams,
0,
allVParams,
tparams.length,
vparams.length);
return new Type.PolyType(tparams,
new Type.MethodType(allVParams,
result));
default:
throw Debug.abort("unexpected type: ", type);
}
} else
return type;
}
private boolean isPrimitive(Symbol sym) {
throw new Error(); // TODO
}
public void apply(Unit[] units) {
transformer.apply(units);
}
private class TV_Transformer extends GenTransformer {
private Symbol currentOwner;
public TV_Transformer(Global global) {
super(global);
}
public Tree transform(Tree tree) {
switch (tree) {
case ClassDef(int mods, //:
Name name,
Tree.AbsTypeDef[] tparams,
Tree.ValDef[][] vparams,
Tree tpe,
Tree.Template impl):
Symbol sym = tree.symbol();
Tree[] newBody = transform(impl.body, impl.symbol());
// Add accessors for type members
Tree[] finalBody;
HashMap/*<Symbol, Symbol>*/ membersToAdd = typeAccessors(sym);
if (!membersToAdd.isEmpty()) {
finalBody = new Tree[newBody.length + membersToAdd.size()];
for (int n = 0, nn = 0; n < newBody.length; ++n) {
finalBody[nn++] = newBody[n];
Symbol memberSym = newBody[n].symbol();
if (membersToAdd.containsKey(memberSym)) {
Symbol symToAdd =
(Symbol)membersToAdd.get(memberSym);
Tree rhs = memberSym.isAbstractType()
? Tree.Empty
: typeAsValue(newBody[n].pos,
memberSym.type(),
symToAdd);
finalBody[nn++] = gen.DefDef(symToAdd, rhs);
}
}
} else
finalBody = newBody;
return gen.ClassDef(sym,
transform(impl.parents),
impl.symbol(),
finalBody);
case DefDef(_, _, _, _, _, Tree rhs):
Symbol symbol = getSymbolFor(tree);
return gen.DefDef(symbol, transform(rhs, symbol));
case ValDef(_, _, Tree tpe, Literal(AConstant.ZERO)):
// transform default values:
// val x: T = _
// becomes
// val x: T = asValue(T).defaultValue()
Symbol symbol = getSymbolFor(tree);
Tree defaultValue =
gen.mkRef(tree.pos,
typeAsValue(tree.pos, tpe.type, currentOwner),
defs.TYPE_DEFAULTVALUE());
Tree rhs = gen.mkApply__(tree.pos, defaultValue);
return gen.ValDef(symbol, rhs);
case ValDef(_, _, _, Tree rhs):
Symbol symbol = getSymbolFor(tree);
return gen.ValDef(symbol, transform(rhs, symbol));
case New(Apply(TypeApply(Tree fun, Tree[] targs), Tree[] vargs)):
if (fun.symbol() == ARRAY_CONSTRUCTOR) {
// Transform array creations:
// new Array[T](size)
// becomes
// asValue(T).newArray[T](size)
assert targs.length == 1;
assert vargs.length == 1;
Tree newArrayfun = gen.mkRef(tree.pos,
typeAsValue(targs[0].pos,
targs[0].type,
currentOwner),
defs.TYPE_NEWARRAY());
return gen.mkApplyTV(newArrayfun, targs, vargs);
} else
return super.transform(tree);
case Apply(TypeApply(Tree fun, Tree[] targs), Tree[] vargs):
Symbol funSym = fun.symbol();
if (funSym == defs.ANY_IS) {
// Transform instance tests:
// e.isInstanceOf[T]
// becomes:
// asValue(T).hasAsInstance(e)
// unless T is a "simple" type for which a Java
// instance test is sufficient, in which case the
// expression is left as is.
assert targs.length == 1 && vargs.length == 0;
Tree tp = targs[0];
if (isTrivialType(tp.type))
return super.transform(tree);
else {
Tree tpV = typeAsValue(tp.pos, tp.type, currentOwner);
Tree hasAsInst =
gen.Select(tp.pos, tpV, defs.TYPE_HASASINSTANCE());
return gen.mkApply_V(tree.pos,
hasAsInst,
new Tree[] {
extractQualifier(fun)
});
}
} else if (funSym == defs.ANY_AS) {
// Transform instance tests:
// e.asInstanceOf[T]
// becomes:
// asValue(T).checkCastability(e).asInstanceOf[T]
// unless T is a "simple" type for which a Java
// instance test is sufficient, in which case the
// expression is left as is.
assert targs.length == 1 && vargs.length == 0;
return super.transform(tree); // TODO
} else {
// Transform applications to pass types as values:
// f[T1, ...](v1, ...)
// becomes
// f[T1, ...](asValue(T1), ..., v1, ...)
Tree[] newVArgs = transform(vargs);
Tree[] finalVArgs =
new Tree[newVArgs.length + targs.length];
for (int i = 0; i < targs.length; ++i)
finalVArgs[i] = typeAsValue(targs[i].pos,
targs[i].type,
currentOwner);
System.arraycopy(newVArgs, 0,
finalVArgs, targs.length,
newVArgs.length);
return gen.mkApplyTV(tree.pos,
transform(fun),
targs,
finalVArgs);
}
default:
return super.transform(tree);
}
}
private Tree transform(Tree tree, Symbol currentOwner) {
Symbol bkpOwner = this.currentOwner;
this.currentOwner = currentOwner;
Tree newTree = transform(tree);
this.currentOwner = bkpOwner;
return newTree;
}
private Tree[] transform(Tree[] trees, Symbol currentOwner) {
Symbol bkpOwner = this.currentOwner;
this.currentOwner = currentOwner;
Tree[] newTrees = transform(trees);
this.currentOwner = bkpOwner;
return newTrees;
}
/**
* Return true iff the given type is "trivial", that is if it
* is representable as a Java type without loss of
* information.
*/
private boolean isTrivialType(Type tp) {
switch (tp) {
case ConstantType(Type base, _):
return isTrivialType(base);
case TypeRef(_, Symbol sym, Type[] args):
return sym.isStatic() && args.length == 0;
case SingleType(_, _):
case ThisType(_): // TODO check
case CompoundType(_, _): // TODO check
return false;
default:
throw Debug.abort("unexpected type", tp);
}
}
/**
* Transform a type into a tree representing it.
*/
private Tree typeAsValue(int pos, Type tp, Symbol owner) {
switch (tp) {
case ConstantType(Type base, _):
return typeAsValue(pos, base, owner);
case TypeRef(Type pre, Symbol sym, Type[] args): {
Symbol symOwner = sym.owner();
if (basicTypes.containsKey(sym)) {
return gen.mkGlobalRef(pos, (Symbol)basicTypes.get(sym));
} else if (symOwner.isClass() || symOwner.isMethod()) {
// Reference to a "local" type.
Symbol accessor = getAccessorSymbol(sym);
if (accessor.isMethod())
return gen.mkApply__(gen.mkLocalRef(pos, accessor));
else
return gen.mkLocalRef(pos, accessor);
} else {
// Reference to a "non-local" type.
Tree[] ctorArgs = new Tree[args.length + 2];
ctorArgs[0] = symOwner.isPackage()
? gen.mkNullLit(pos)
: prefixAsValue(pos, pre);
ctorArgs[1] =
gen.mkStringLit(pos, prims.getJREClassName(sym));
for (int i = 0; i < args.length; ++i)
ctorArgs[i + 2] = typeAsValue(pos, args[i], owner);
Symbol typeConstr =
defs.CONSTRUCTEDTYPE_CTOR(args.length);
return gen.New(pos,
gen.mkApply_V(gen.mkGlobalRef(pos,
typeConstr),
ctorArgs));
}
}
case SingleType(Type pre, Symbol sym): {
Tree constr =
gen.mkPrimaryConstructorGlobalRef(pos, singleTypeClass);
Tree[] args = new Tree[] { gen.mkRef(pos, pre, sym) };
return gen.New(pos, gen.mkApply_V(constr, args));
}
default:
throw global.fail("unexpected type: ", tp);
}
}
/**
* Extract qualifier from a tree, which must be a Select node.
*/
private Tree extractQualifier(Tree tree) {
switch (tree) {
case Select(Tree qualifier, _): return qualifier;
default: throw Debug.abort("cannot extract qualifier from ", tree);
}
}
/**
* Transform a prefix into a tree representing it.
*/
private Tree prefixAsValue(int pos, Type pre) {
switch (pre) {
case ThisType(Symbol clazz):
if (clazz.isPackage() || clazz.isNone())
return gen.mkNullLit(pos);
else
return gen.This(pos, clazz);
case SingleType(Type prefix, Symbol member):
return gen.mkApply__(pos,
gen.mkRef(pos,
prefixAsValue(pos, prefix),
member));
default:
throw Debug.abort("unexpected prefix", pre);
}
}
}
}
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