From 4177daab2f54bdb20c71f623296a8bb32616fd12 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Thu, 13 Feb 2003 14:41:36 +0000
Subject: Initial version.

---
 sources/scalac/symtab/Symbol.java | 1291 +++++++++++++++++++++++++++++++++++++
 1 file changed, 1291 insertions(+)
 create mode 100644 sources/scalac/symtab/Symbol.java

(limited to 'sources/scalac/symtab/Symbol.java')

diff --git a/sources/scalac/symtab/Symbol.java b/sources/scalac/symtab/Symbol.java
new file mode 100644
index 0000000000..f13192848b
--- /dev/null
+++ b/sources/scalac/symtab/Symbol.java
@@ -0,0 +1,1291 @@
+/*     ____ ____  ____ ____  ______                                     *\
+**    / __// __ \/ __// __ \/ ____/    SOcos COmpiles Scala             **
+**  __\_ \/ /_/ / /__/ /_/ /\_ \       (c) 2002, LAMP/EPFL              **
+** /_____/\____/\___/\____/____/                                        **
+**
+** $Id$
+\*                                                                      */
+
+//todo check significance of JAVA flag.
+
+package scalac.symtab;
+
+import scalac.ApplicationError;
+import scalac.Global;
+import scalac.PhaseDescriptor;
+import scalac.util.ArrayApply;
+import scalac.util.Name;
+import scalac.util.Names;
+import scalac.util.NameTransformer;
+import scalac.util.Position;
+import scalac.util.Debug;
+import scalac.symtab.classfile.*;
+
+
+public abstract class Symbol implements Modifiers, Kinds {
+
+    /** An empty symbol array */
+    public static final Symbol[] EMPTY_ARRAY = new Symbol[0];
+
+    /** An empty array of symbol arrays */
+    public static final Symbol[][] EMPTY_ARRAY_ARRAY = new Symbol[0][];
+
+    /** The error symbol */
+    public static final ErrorSymbol ERROR = new ErrorSymbol();
+
+    /** The absent symbol */
+    public static final NoSymbol NONE = new NoSymbol();
+
+// Fields -------------------------------------------------------------
+
+    /** The kind of the symbol */
+    public int kind;
+
+    /** The position of the symbol */
+    public int pos;
+
+    /** The name of the symbol */
+    public Name name;
+
+    /** The modifiers of the symbol */
+    public int flags;
+
+    /** The owner of the symbol */
+    private Symbol owner;
+
+    /** The infos of the symbol */
+    private TypeIntervalList infos = TypeIntervalList.EMPTY;
+
+// Constructors -----------------------------------------------------------
+
+    /** Generic symbol constructor */
+    public Symbol(int kind, int pos, Name name, Symbol owner, int flags) {
+	assert (!isTerm() || !name.isTypeName()) && (!isType() || name.isTypeName());
+
+        this.kind = kind;
+        this.pos = pos;
+        this.name = name;
+        this.owner = owner;
+        this.flags = flags & ~(INITIALIZED | LOCKED); // safety first
+    }
+
+    /** Return a fresh symbol with the same fields as this one.
+     */
+    public abstract Symbol cloneSymbol();
+
+    /** copy all fields to `sym'
+     */
+    public void copyTo(Symbol sym) {
+	sym.kind = kind;
+	sym.pos = pos;
+	sym.name = name;
+	sym.flags = flags;
+	sym.owner = owner;
+	sym.infos = infos;
+    }
+
+// Setters ---------------------------------------------------------------
+
+    /** Set the mangled name of this Symbol */
+    public Symbol setMangledName(Name name) {
+        throw new ApplicationError("illegal operation on " + getClass());
+    }
+
+    /** Set owner */
+    public Symbol setOwner(Symbol owner) {
+        this.owner = owner;
+        return this;
+    }
+
+    /** Set information, except if symbol is both initialized and locked.
+     */
+    public Symbol setInfo(Type info) {
+	return setInfo(info, currentPhaseId());
+    }
+
+    public Symbol setInfo(Type info, int limit) {
+	if ((flags & (INITIALIZED | LOCKED)) != (INITIALIZED | LOCKED)) {
+	    if (infos == TypeIntervalList.EMPTY)
+		infos = new TypeIntervalList(TypeIntervalList.EMPTY);
+	    infos.limit = limit;
+	    infos.info = info;
+	}
+        return this;
+    }
+
+    /** Set type -- this is an alias for setInfo(Type info) */
+    public Symbol setType(Type info) { return setInfo(info); }
+
+    public Symbol updateInfo(Type info) {
+	// Global.instance.currentPhase.setInfo(this, info);
+	if (infos.limit <= Global.instance.currentPhase.id) {
+	    infos = new TypeIntervalList(infos);
+	    infos.limit = Global.instance.currentPhase.id + 1;
+	} else {
+	    assert infos.limit == Global.instance.currentPhase.id + 1 : this;
+	}
+	infos.info = info;
+	return this;
+    }
+
+// Symbol classification ----------------------------------------------------
+
+    /** Does this symbol denote a type? */
+    public final boolean isType() {
+	return kind == TYPE || kind == CLASS || kind == ALIAS;
+    }
+
+    /** Does this symbol denote a term? */
+    public final boolean isTerm() {
+	return kind == VAL;
+    }
+
+    /** Does this symbol denote a value? */
+    public final boolean isValue() {
+        return kind == VAL && !(isModule() && isJava()) && !isPackage();
+    }
+
+    /** Does this symbol denote a variable? */
+    public final boolean isVariable() {
+        return kind == VAL && (flags & MUTABLE) != 0;
+    }
+
+    /** Does this symbol denote a method?
+     */
+    public final boolean isInitializedMethod() {
+	if (infos.limit < 0) return false;
+	switch (rawInfo()) {
+	case MethodType(_, _):
+	case PolyType(_, _): return true;
+	default: return false;
+	}
+    }
+
+    public final boolean isMethod() {
+	initialize();
+	return isInitializedMethod();
+    }
+
+    /* Does this symbol denote an anonymous class? */
+    public final boolean isAnonymousClass() {
+	return kind == CLASS &&
+	    (name == Names.EMPTY.toTypeName() ||
+	     name == Names.ANON_CLASS_NAME.toTypeName());
+    }
+
+    /** Does this symbol denote the root class or root module?
+     */
+    public final boolean isRoot() {
+	return this.moduleClass() == Global.instance.definitions.ROOT_CLASS;
+    }
+
+    /** Does this symbol denote something loaded from a Java class? */
+    public final boolean isJava() {
+        return (flags & JAVA) != 0;
+    }
+
+    /** Does this symbol denote a Java package? */
+    public final boolean isPackage() {
+        return (flags & PACKAGE) != 0;
+    }
+
+    /** Does this symbol denote a module? */
+    public final boolean isModule() {
+        return kind == VAL && (flags & MODUL) != 0;
+    }
+
+    /** Does this symbol denote a module? */
+    public final boolean isModuleClass() {
+        return kind == CLASS && (flags & MODUL) != 0;
+    }
+
+    /** Does this symbol denote a module? */
+    public final boolean isClass() {
+        return kind == CLASS;
+    }
+
+    /** Does this symbol denote a case class?
+     */
+    public final boolean isCaseClass() {
+	return kind == CLASS && (flags & CASE) != 0;
+    }
+
+    /** Does this symbol denote a uniform (i.e. parameterless) class? */
+    public final boolean isTrait() {
+	return kind == CLASS && (flags & TRAIT) != 0;
+    }
+
+    /** Does this class symbol denote a compound type symbol?
+     */
+    public final boolean isCompoundSym() {
+	return name == Names.COMPOUND_NAME.toTypeName();
+    }
+
+    /** Does this symbol denote an interface? */
+    public final boolean isInterface() {
+        return (flags & INTERFACE) != 0;
+    }
+
+    /** Does this symbol denote a static member? */
+    public final boolean isStatic() {
+        return (flags & STATIC) != 0;
+    }
+
+    /** Is this symbol locally defined? I.e. not a member of a class or module */
+    public final boolean isLocal() {
+	return owner.kind == VAL && !owner.isPrimaryConstructor();
+    }
+
+    /** Is this symbol a parameter? Includes type parameters of methods.
+     */
+    public final boolean isParameter() {
+	return (flags & PARAM) != 0;
+    }
+
+    /** Is this symbol a def parameter?
+     */
+    public final boolean isDefParameter() {
+	return (flags & (PARAM | DEF)) == (PARAM | DEF);
+    }
+
+    /** Is this class locally defined?
+     *  A class is local, if
+     *   - it is anonymous, or
+     *   - its owner is a value
+     *   - it is defined within a local class
+     */
+    public final boolean isLocalClass() {
+	return kind == CLASS &&
+	    !isPackage() &&
+	    (name == Names.EMPTY.toTypeName() ||
+	     owner.isValue() ||
+	     owner.isLocalClass());
+    }
+
+    /** Is this symbol a constructor? */
+    public final boolean isConstructor() {
+	return name.isConstrName();
+    }
+
+    /** Is this symbol the primary constructor of a type? */
+    public final boolean isPrimaryConstructor() {
+	return isConstructor() && this == constructorClass().constructor();
+    }
+
+    public boolean isGenerated() {
+	return name.pos((byte)'$') < name.length();
+    }
+
+    /** Symbol was preloaded from package
+     */
+    public boolean isPreloaded() {
+	return owner.isPackage() && pos == Position.NOPOS;
+    }
+
+// Symbol names ----------------------------------------------------------------
+
+    /** Get the fully qualified name of this Symbol
+     *  (this is always a normal name, never a type name)
+     */
+    public Name fullName() {
+        return name.toTermName();
+    }
+
+    /** Get the mangled name of this Symbol
+     *  (this is always a normal name, never a type name)
+     */
+    public Name mangledName() {
+        return name.toTermName();
+    }
+
+    /** Get the fully qualified mangled name of this Symbol */
+    public Name mangledFullName() {
+        return fullName().replace((byte)'.', (byte)'$');
+    }
+
+// Acess to related symbols -----------------------------------------------------
+
+    /** Get type parameters */
+    public Symbol[] typeParams() {
+	return EMPTY_ARRAY;
+    }
+
+    /** Get primary constructor of class */
+    public Symbol constructor() {
+        return NONE;
+    }
+
+    /** Get module associated with class */
+    public Symbol module() {
+        return NONE;
+    }
+
+    /** Get owner */
+    public Symbol owner() {
+        return owner;
+    }
+
+    /** Get owner, but if owner is primary constructor of a class,
+     *  get class symbol instead. This is useful for type parameters
+     *  and value parameters in classes which have the primary constructor
+     *  as owner.
+     */
+    public Symbol classOwner() {
+	Symbol owner = owner();
+	Symbol clazz = owner.constructorClass();
+	if (clazz.constructor() == owner) return clazz;
+	else return owner;
+    }
+
+    /** The next enclosing class */
+    public Symbol enclClass() {
+        return owner().enclClass();
+    }
+
+    /** The top-level class enclosing `sym'
+     */
+    Symbol enclToplevelClass() {
+	Symbol sym = this;
+	while (sym.kind == VAL ||
+	       (sym.kind == CLASS && !sym.owner().isPackage())) {
+	    sym = sym.owner();
+	}
+	return sym;
+    }
+
+     /* If this is a constructor, return the class it constructs.
+     *  Otherwise return the symbol itself.
+     */
+    public Symbol constructorClass() {
+	return this;
+    }
+
+     /* If this is a module, return its class.
+     *  Otherwise return the symbol itself.
+     */
+    public Symbol moduleClass() {
+	return this;
+    }
+
+    /** The symbol accessed by this accessor function.
+     */
+    public Symbol accessed() {
+	assert (flags & ACCESSOR) != 0;
+	Name name1 = name;
+	if (name1.endsWith(Names._EQ))
+	    name1 = name1.subName(0, name1.length() - Names._EQ.length());
+	return owner.info().lookup(Name.fromString(name1 + "$"));
+    }
+
+    /** The members of this class or module symbol
+     */
+    public Scope members() {
+	return info().members();
+    }
+
+// Symbol types --------------------------------------------------------------
+
+    /** Was symbol's type updated during phase `id'?
+     */
+    public boolean isUpdated(int id) {
+	return infos.limit >= id;
+    }
+
+    /** the current phase id, or the id after analysis, whichever is larger.
+     */
+    int currentPhaseId() {
+	int id = Global.instance.currentPhase.id;
+	if (id > Global.instance.POST_ANALYZER_PHASE_ID)
+	    id = Global.instance.POST_ANALYZER_PHASE_ID;
+	return id;
+    }
+
+    /** Is this symbol initialized? */
+    public final boolean isInitialized() {
+        return (flags & INITIALIZED) != 0;
+    }
+
+    /** Initialize the symbol */
+    public final Symbol initialize() {
+	info();
+        return this;
+    }
+
+    /** Get info; This is:
+     *  for a term symbol, its type
+     *  for a type variable, its bound
+     *  for a type alias, its right-hand side
+     *  for a class symbol, the compound type consisting of
+     *  its baseclasses and members.
+     */
+    public Type info() {
+	if ((flags & INITIALIZED) == 0) {
+	    int id = currentPhaseId();
+	    Type info = rawInfoAt(id);
+	    assert info != null : this;
+
+	    if ((flags & LOCKED) != 0) {
+	        setInfo(Type.ErrorType);
+		flags |= INITIALIZED;
+		throw new CyclicReference(this, info);
+	    }
+	    flags |= LOCKED;
+	    //System.out.println("completing " + this);//DEBUG
+	    info.complete(this);
+            flags = flags & ~LOCKED;
+	    if (info instanceof SourceCompleter && (flags & SNDTIME) == 0) {
+		flags |= SNDTIME;
+		return info();
+	    } else {
+		assert !(rawInfoAt(id) instanceof Type.LazyType) : this;
+		flags |= INITIALIZED;
+	    }
+	    //System.out.println("done: " + this);//DEBUG
+	}
+	return rawInfoAt(Global.instance.currentPhase.id);
+    }
+
+    /** Get info at phase #id
+     */
+    public Type infoAt(int id) {
+	info();
+	return rawInfoAt(id);
+    }
+
+    /** get info at phase #id, without forcing lazy types.
+     */
+    private Type rawInfoAt(int id) {
+	int nextid = infos.limit;
+	assert infos != TypeIntervalList.EMPTY : this;
+	if (nextid < id) {
+	    do {
+		Type newInfo =
+		    Global.instance.phases[nextid].transformInfo(this, infos.info);
+		if (newInfo != infos.info) {
+		    infos = new TypeIntervalList(infos);
+		    infos.info = newInfo;
+		}
+		nextid++;
+		infos.limit = nextid;
+	    } while (nextid < id);
+	    return infos.info;
+	} else {
+	    TypeIntervalList infos1 = infos;
+	    while (infos1.prev.limit >= id) {
+		infos1 = infos1.prev;
+	    }
+	    return infos1.info;
+	}
+    }
+
+    public Type rawInfo() {
+	return rawInfoAt(Global.instance.currentPhase.id);
+    }
+
+    /** The type of a symbol is:
+     *  for a type symbol, the type corresponding to the symbol itself
+     *  for a term symbol, its usual type
+     */
+    public Type type() {
+	return info();
+    }
+
+    /** The type at phase #id
+     */
+    public Type typeAt(int id) {
+	return infoAt(id);
+    }
+
+    /** The types of these symbols as an array.
+     */
+    static public Type[] type(Symbol[] syms) {
+	Type[] tps = new Type[syms.length];
+	for (int i = 0; i < syms.length; i++)
+	    tps[i] = syms[i].type();
+	return tps;
+    }
+
+    /** Get this.type corresponding to this symbol
+     */
+    public Type thisType() {
+	return Type.localThisType;
+    }
+
+    public Type typeOfThis() {
+	return Type.localThisType;
+    }
+
+    /** A total ordering between symbols that refines the class
+     *  inheritance graph (i.e. subclass.isLess(superclass) always holds).
+     */
+    public boolean isLess(Symbol that) {
+	if (this == that) return false;
+	int diff;
+	if (this.isType()) {
+	    if (that.isType()) {
+		diff = this.closure().length - that.closure().length;
+		if (diff > 0) return true;
+		if (diff < 0) return false;
+	    } else {
+		return true;
+	    }
+	} else if (that.isType()) {
+	    return false;
+	}
+
+	diff = that.mangledName().index - this.mangledName().index;
+	if (diff > 0) return true;
+	if (diff < 0) return false;
+
+	diff = that.mangledFullName().index - this.mangledFullName().index;
+	if (diff > 0) return true;
+	if (diff < 0) return false;
+
+	throw new ApplicationError(
+	    "Giving up: can't order two incarnations of class " +
+	    this.mangledFullName());
+    }
+
+    /** Return the symbol's type itself followed by all its direct and indirect
+     *  base types, sorted by isLess(). Overridden for class symbols.
+     */
+    public Type[] closure() {
+	return info().closure();
+    }
+
+    /** Return position of `c' in the closure of this type; -1 if not there.
+     */
+    public int closurePos(Symbol c) {
+	if (this == c) return 0;
+	if (c.isCompoundSym()) return -1;
+	Type[] closure = closure();
+	int lo = 0;
+	int hi = closure.length - 1;
+	while (lo <= hi) {
+	    int mid = (lo + hi) / 2;
+	    Symbol clsym = closure[mid].symbol();
+	    if (c == clsym) return mid;
+	    else if (c.isLess(clsym)) hi = mid - 1;
+	    else if (clsym.isLess(c)) lo = mid + 1;
+	    else throw new ApplicationError();
+	}
+	return -1;
+    }
+
+    Type baseType(Symbol sym) {
+	int i = closurePos(sym);
+	if (i >= 0) return closure()[i];
+	else return Type.NoType;
+    }
+
+    /** Is this class a subclass of `c'? I.e. does it have a type instance
+     *  of `c' as indirect base class?
+     */
+    public boolean isSubClass(Symbol c) {
+	return this == c || c.kind == Kinds.ERROR || closurePos(c) >= 0;
+    }
+
+// ToString -------------------------------------------------------------------
+
+    /** String representation of symbol's simple name.
+     *  Translates expansions of operators back to operator symbol. E.g.
+     *  $eq => =.
+     */
+    public String nameString() {
+	return NameTransformer.decode(name).toString();
+    }
+
+    /** String representation of symbol's full name.
+     *  Translates expansions of operators back to operator symbol. E.g.
+     *  $eq => =.
+     */
+    public String fullNameString() {
+	return NameTransformer.decode(fullName()).toString();
+    }
+
+    public String idString() {
+	if (Global.instance.uniqid &&
+	    (kind == TYPE || Global.instance.debug))
+	    return "#" + Global.instance.uniqueID.id(this);
+	else return "";
+    }
+
+    /** String representation, including symbol's kind
+     *  e.g., "class Foo", "function Bar".
+     */
+    public String toString() {
+	if (isRoot()) return "<root package>";
+	if (isAnonymousClass()) return "<template>";
+	String kstr = kindString();
+	String str;
+	if (kstr.length() == 0) str = fullNameString();
+	else str = kstr + " " + fullNameString();
+	return str + idString();
+    }
+
+    /** String representation of location.
+     */
+    public String locationString() {
+	if (owner.kind == CLASS && !owner.isAnonymousClass())
+	    return " in " + owner;
+	else
+	    return "";
+    }
+
+    /** String representation of definition.
+     */
+    public String defString() {
+	String inner;
+	if (kind == CLASS) inner = " extends ";
+	else if (kind == TYPE) inner = " <: ";
+	else if (kind == ALIAS) inner = " = ";
+	else inner = " : ";
+	return
+	    (isParameter() ? "" : defKeyword() + " ") +
+	    nameString() + idString() + inner +
+            (rawInfoAt(Global.instance.POST_ANALYZER_PHASE_ID)
+	       instanceof Type.LazyType ? "?" : info());
+    }
+
+    public static String[] defString(Symbol[] defs) {
+	String[] strs = new String[defs.length];
+	for (int i = 0; i < defs.length; i++)
+	    strs[i] = defs[i].defString();
+	return strs;
+    }
+
+    /** String representation of kind */
+    public String kindString() {
+	switch (kind) {
+        case CLASS:
+	    if ((flags & TRAIT) != 0)
+		return "trait";
+	    else if ((flags & MODUL) != 0 && Global.instance.debug)
+		return "module class";
+	    else
+		return "class";
+	case TYPE:
+        case ALIAS:
+	    return "type";
+        case VAL:
+	    if (isVariable()) return "variable";
+	    else if (isModule()) return "module";
+	    else if (isConstructor()) return "constructor";
+	    else if (isInitializedMethod()) return "method";
+	    else return "value";
+	default: return "";
+	}
+    }
+
+    /** Definition keyword of kind
+     */
+    public String defKeyword() {
+	switch (kind) {
+        case CLASS: if ((flags & TRAIT) != 0) return "trait"; else return "class";
+	case TYPE:
+        case ALIAS: return "type";
+        case VAL:
+	    if (isVariable()) return "var";
+	    else if (isModule()) return "module";
+	    else if (isInitializedMethod()) return "def";
+	    else return "val";
+	default: return "";
+	}
+    }
+
+// Overloading and Overriding -------------------------------------------
+
+    /** Add another overloaded alternative to this symbol.
+     */
+    public Symbol overloadWith(Symbol that) {
+        assert isTerm() : this;
+	assert this.name == that.name : this + " " + that;
+	assert this.owner == that.owner : this + " " + that;
+	assert (this.flags & that.flags & JAVA) != 0 ||
+	    (this.flags & (SOURCEFLAGS | JAVA) & ~ACCESSFLAGS) ==
+	    (that.flags & (SOURCEFLAGS | JAVA) & ~ACCESSFLAGS) : this + " " + that;
+        TermSymbol overloaded = new TermSymbol(
+            pos, name, owner,
+	    ((this.flags | that.flags) & (SOURCEFLAGS | JAVA) & ~ACCESSFLAGS) |
+	    (this.flags & that.flags & ACCESSFLAGS));
+        overloaded.setInfo(new LazyOverloadedType(this, that));
+        return overloaded;
+    }
+
+    /** A lazy type which, when forced computed the overloaded type
+     *  of symbols `sym1' and `sym2'. It also checks that this type is well-formed.
+     */
+    private static class LazyOverloadedType extends Type.LazyType {
+	Symbol sym1;
+	Symbol sym2;
+	LazyOverloadedType(Symbol sym1, Symbol sym2) {
+	    this.sym1 = sym1;
+	    this.sym2 = sym2;
+	}
+	private Symbol[] alts(Symbol sym) {
+	    if (sym == null) return Symbol.EMPTY_ARRAY;
+	    switch (sym.type()) {
+	    case OverloadedType(Symbol[] alts, _): return alts;
+	    default: return new Symbol[]{sym};
+	    }
+	}
+	private Type[] alttypes(Symbol sym) {
+	    if (sym == null) return Type.EMPTY_ARRAY;
+	    switch (sym.type()) {
+	    case OverloadedType(_, Type[] alttypes): return alttypes;
+	    default: return new Type[]{sym.type()};
+	    }
+	}
+	public void complete(Symbol overloaded) {
+	    if (sym1 != null) sym1.initialize();
+	    if (sym2 != null) sym2.initialize();
+
+	    Symbol[] alts1 = alts(sym1);
+	    Symbol[] alts2 = alts(sym2);
+	    Symbol[] alts3 = new Symbol[alts1.length + alts2.length];
+	    System.arraycopy(alts1, 0, alts3, 0, alts1.length);
+	    System.arraycopy(alts2, 0, alts3, alts1.length, alts2.length);
+
+	    Type[] alttypes1 = alttypes(sym1);
+	    Type[] alttypes2 = alttypes(sym2);
+	    Type[] alttypes3 = new Type[alttypes1.length + alttypes2.length];
+	    System.arraycopy(alttypes1, 0, alttypes3, 0, alttypes1.length);
+	    System.arraycopy(alttypes2, 0, alttypes3, alttypes1.length, alttypes2.length);
+	    overloaded.setInfo(Type.OverloadedType(alts3, alttypes3));
+	}
+    }
+
+    /** All the alternatives of this symbol if it's overloaded, the
+     * symbol alone otherwise.
+     */
+    public Symbol[] alternatives() {
+	switch (type()) {
+	case OverloadedType(Symbol[] alts, _): return alts;
+	default: return new Symbol[]{this};
+        }
+    }
+
+    /** The symbol which is overridden by this symbol in base class `base'
+     *  `base' must be a superclass of this.owner().
+     */
+    public Symbol overriddenSymbol(Type base) {
+	Symbol sym1 = base.lookupNonPrivate(name);
+	if (sym1.kind == Kinds.NONE || (sym1.flags & STATIC) != 0) {
+	    return Symbol.NONE;
+	} else {
+	    //System.out.println(this + ":" + this.type() + locationString() + " overrides? " + sym1 + sym1.type() + sym1.locationString()); //DEBUG
+
+	    Type symtype = owner.thisType().memberType(this);
+	    //todo: try whether we can do: this.type(); instead
+	    Type sym1type = owner.thisType().memberType(sym1);
+	    switch (sym1type) {
+	    case OverloadedType(Symbol[] alts, Type[] alttypes):
+		for (int i = 0; i < alts.length; i++) {
+		    if (symtype.isSameAs(alttypes[i])) return alts[i];
+		}
+		return Symbol.NONE;
+	    default:
+		if (symtype.isSameAs(sym1type)) return sym1;
+		else {
+		    System.out.println(this + locationString() + " does not override " + sym1 + sym1.locationString() + ", since " + symtype + " # " + sym1type);//DEBUG
+		    return Symbol.NONE;
+		}
+	    }
+	}
+    }
+}
+
+/** A class for term symbols
+ */
+public class TermSymbol extends Symbol {
+
+    private Symbol clazz;
+
+    /** Constructor */
+    public TermSymbol(int pos, Name name, Symbol owner, int flags) {
+        super(VAL, pos, name, owner, flags);
+    }
+
+    public static TermSymbol newConstructor(Symbol clazz, int flags) {
+        TermSymbol sym = new TermSymbol(
+	    clazz.pos, clazz.name.toConstrName(), clazz.owner(),
+	    flags | FINAL);
+	sym.clazz = clazz;
+	return sym;
+    }
+
+    public static TermSymbol newJavaConstructor(Symbol clazz) {
+	return newConstructor(clazz, clazz.flags & (ACCESSFLAGS | QUALIFIED | JAVA));
+    }
+
+    public static TermSymbol newModule(int pos, Name name, Symbol owner, int flags) {
+	TermSymbol sym = new TermSymbol(pos, name, owner, flags | MODUL | FINAL);
+        Symbol clazz = new ClassSymbol(
+	    pos, name.toTypeName(), owner, flags | MODUL | FINAL, sym);
+	Type clazztype = Type.TypeRef(owner.thisType(), clazz, Type.EMPTY_ARRAY);
+        clazz.constructor().setInfo(Type.MethodType(Symbol.EMPTY_ARRAY, clazztype));
+	sym.clazz = clazz;
+	sym.setInfo(clazztype);
+	return sym;
+    }
+
+    /** Constructor for companion modules to classes, which need to be completed.
+     */
+    public static TermSymbol newCompanionModule(Symbol clazz, int flags, Type.LazyType parser) {
+        TermSymbol sym = newModule(Position.NOPOS, clazz.name.toTermName(), clazz.owner(),
+				   FINAL | flags);
+        sym.clazz.setInfo(parser);
+	return sym;
+    }
+
+    /** Java package module constructor
+     */
+    public static TermSymbol newJavaPackageModule(Name name, Symbol owner, Type.LazyType parser) {
+        TermSymbol sym = newModule(Position.NOPOS, name, owner, JAVA | PACKAGE);
+        sym.clazz.flags |= SYNTHETIC;
+        sym.clazz.setInfo(parser);
+	return sym;
+    }
+
+    /** Get this.type corresponding to this class or module
+     */
+    public Type thisType() {
+	if ((flags & MODUL) != 0) return moduleClass().thisType();
+	else return Type.localThisType;
+    }
+    /** Get the fully qualified name of this Symbol */
+    public Name fullName() {
+	if ((flags & MODUL) != 0) return moduleClass().fullName();
+	else return super.fullName();
+    }
+
+    /** Return a fresh symbol with the same fields as this one.
+     */
+    public Symbol cloneSymbol() {
+        assert !isPrimaryConstructor() : Debug.show(this);
+        TermSymbol other;
+	if (isModule()) {
+	    other = newModule(pos, name, owner(), flags);
+	} else {
+	    other = new TermSymbol(pos, name, owner(), flags);
+	    other.clazz = clazz;
+	}
+        other.setInfo(info());
+        return other;
+    }
+
+    public Symbol constructorClass() {
+	return isConstructor() ? clazz : this;
+    }
+
+    public Symbol moduleClass() {
+	return (flags & MODUL) != 0 ? clazz : this;
+    }
+}
+
+/** A class for (abstract and alias) type symbols. It has ClassSymbol as a subclass.
+ */
+public class TypeSymbol extends Symbol {
+
+     /** A cache for closures
+     */
+    private ClosureIntervalList closures = ClosureIntervalList.EMPTY;
+
+    /** The symbol's type template */
+    private Type template;
+
+    /** The primary constructor of this type */
+    public final Symbol constructor;
+
+    /** Constructor */
+    public TypeSymbol(int kind, int pos, Name name, Symbol owner, int flags) {
+        super(kind, pos, name, owner, flags);
+        this.constructor = TermSymbol.newConstructor(this, flags);
+	if (kind == TYPE) { // provide a constructor type
+	    this.constructor().setInfo(
+		Type.PolyType(Symbol.EMPTY_ARRAY, Type.NoType));
+	}
+    }
+
+    /** Return a fresh symbol with the same fields as this one.
+     */
+    public Symbol cloneSymbol() {
+	if (Global.instance.debug) System.out.println("cloning " + this + this.locationString());
+        TypeSymbol other = new TypeSymbol(kind, pos, name, owner(), flags);
+        other.setInfo(info());
+	other.constructor.setInfo(constructor.info());
+        return other;
+    }
+
+    /** Get self type */
+    public Type type() {
+	if (template == null || template.typeArgs().length != typeParams().length) {
+	    template = Type.TypeRef(
+		owner().thisType(), this, type(typeParams()));
+	}
+	return template;
+    }
+
+    //todo: needed?
+    public Type typeAt(int id) {
+	return type();
+    }
+
+    /** Get type parameters */
+    public Symbol[] typeParams() {
+	return constructor.info().typeParams();
+    }
+
+    /** Get primary constructor */
+    public Symbol constructor() {
+        return constructor;
+    }
+
+    public Type[] closure() {
+	if (kind == ALIAS) return info().symbol().closure();
+	int id = Global.instance.currentPhase.id;
+	if (closures.limit < id) {
+	    if (id == 0 || changes(closureAt(id - 1))) {
+		closures = new ClosureIntervalList(closures);
+		closures.limit = id;
+		computeClosure();
+	    } else {
+		closures.limit = id;
+	    }
+	    return closures.closure;
+	} else {
+	    ClosureIntervalList closures1 = closures;
+	    while (closures1.prev.limit >= id) {
+		closures1 = closures1.prev;
+	    }
+	    return closures1.closure;
+	}
+    }
+
+    //todo: needed?
+    private Type[] closureAt(int id) {
+	PhaseDescriptor savedPhase = Global.instance.currentPhase;
+	Global.instance.currentPhase = Global.instance.phases[id];
+	Type[] c = closure();
+	Global.instance.currentPhase = savedPhase;
+	return c;
+    }
+
+    private boolean changes(Type[] closure) {
+	for (int i = 0; i < closure.length; i++) {
+	    Symbol c = closure[i].symbol();
+	    if (c.infoAt(Global.instance.currentPhase.id - 1) != c.info())
+		return true;
+	}
+	return false;
+    }
+
+    private static Type[] BAD_CLOSURE = new Type[0];
+
+    /** Return the type itself followed by all direct and indirect
+     *  base types of this type, sorted by isLess().
+     */
+    private void computeClosure() {
+	assert closures.closure != BAD_CLOSURE : this;
+	closures.closure = BAD_CLOSURE; // to catch cycles.
+	SymSet closureClassSet = inclClosureBases(SymSet.EMPTY, this);
+	Symbol[] closureClasses = new Symbol[closureClassSet.size() + 1];
+	closureClasses[0] = this;
+	closureClassSet.copyToArray(closureClasses, 1);
+	//System.out.println(ArrayApply.toString(closureClasses));//DEBUG
+	closures.closure = Symbol.type(closureClasses);
+	//System.out.println(ArrayApply.toString(closures.closure));//DEBUG
+	adjustType(type());
+	//System.out.println("closure(" + this + ") at " + Global.instance.currentPhase.name() + " = " + ArrayApply.toString(closures.closure));//DEBUG
+    }
+    //where
+
+ 	private SymSet inclClosureBases(SymSet set, Symbol c) {
+	    Type[] parents = c.type().parents();
+	    for (int i = 0; i < parents.length; i++) {
+		set = inclClosure(set, parents[i].symbol());
+	    }
+	    return set;
+	}
+
+ 	private SymSet inclClosure(SymSet set, Symbol c) {
+	    Symbol c1 = c;
+	    while (c1.kind == ALIAS) c1 = c1.info().symbol();
+	    return inclClosureBases(set.incl(c1), c1);
+	}
+
+	void adjustType(Type tp) {
+	    Type tp1 = tp.unalias();
+	    int pos = closurePos(tp1.symbol());
+	    assert pos >= 0 : this + " " + tp1 + " " + tp1.symbol();
+	    closures.closure[pos] = tp1;
+	    Type[] parents = tp1.parents();
+	    for (int i = 0; i < parents.length; i++) {
+		adjustType(parents[i]);
+	    }
+	}
+}
+
+/** A class for class symbols. It has JavaClassSymbol as a subclass.
+ */
+public class ClassSymbol extends TypeSymbol {
+
+    /** The mangled class name */
+    private Name mangled;
+
+    /** The module belonging to the class. This means:
+     *  For Java classes, its statics parts.
+     *  For module classes, the corresponding module.
+     *  For other classes, null.
+     */
+    private Symbol module = NONE;
+
+    /** Principal Constructor for module classes and classes with static members.
+     */
+    public ClassSymbol(int pos, Name name, Symbol owner, int flags) {
+        super(CLASS, pos, name, owner, flags);
+        this.mangled = name;
+    }
+
+    /** Constructor for module classes and classes with static members.
+     */
+    public ClassSymbol(int pos, Name name, Symbol owner, int flags, Symbol module) {
+	this(pos, name, owner, flags);
+	this.module = module;
+    }
+
+    /** Constructor for classes to load as source files
+     */
+    public ClassSymbol(Name name, Symbol owner, SourceCompleter parser) {
+	this(Position.NOPOS, name, owner, 0);
+	this.module = TermSymbol.newCompanionModule(this, 0, parser);
+        this.mangled = name;
+        this.setInfo(parser);
+    }
+
+    /** Constructor for classes to load as class files.
+     */
+    public ClassSymbol(Name name, Symbol owner, ClassParser parser) {
+	super(CLASS, Position.NOPOS, name, owner, JAVA);
+	this.module = TermSymbol.newCompanionModule(this, JAVA, parser.staticsParser(this));
+        this.mangled = name;
+        this.setInfo(parser);
+    }
+
+    /** Return a fresh symbol with the same fields as this one.
+     */
+    public Symbol cloneSymbol() {
+        ClassSymbol other = new ClassSymbol(pos, name, owner(), flags);
+        other.setInfo(info());
+	other.constructor.setInfo(constructor.info());
+	other.mangled = mangled;
+	other.module = module;
+        return other;
+    }
+
+   /** Get module */
+    public Symbol module() {
+        return module;
+    }
+
+    /** Set the mangled name of this Symbol */
+    public Symbol setMangledName(Name name) {
+        this.mangled = name;
+        return this;
+    }
+
+    /** Get the fully qualified name of this Symbol */
+    public Name fullName() {
+        if (owner().kind == CLASS && owner().name.length() != 0)
+            return Name.fromString(owner().fullName() + "." + name);
+        else
+            return name.toTermName();
+    }
+
+    /** Get the mangled name of this Symbol */
+    public Name mangledName() {
+        return mangled;
+    }
+
+    /** Get the fully qualified mangled name of this Symbol */
+    public Name mangledFullName() {
+	if (mangled == name) {
+	    return fullName().replace((byte)'.', (byte)'$');
+	} else {
+	    return Name.fromString(
+		enclToplevelClass().mangledFullName() + "$" + mangled);
+	}
+    }
+
+    private Type thistp = Type.ThisType(this);
+
+    public Type thisType() {
+	return thistp;
+    }
+
+    /** Return the next enclosing class */
+    public Symbol enclClass() {
+        return this;
+    }
+
+    public Symbol caseFieldAccessor(int index) {
+	assert (flags & CASE) != 0 : this;
+	Scope.SymbolIterator it = info().members().iterator();
+	Symbol sym = null;
+	for (int i = 0; i <= index; i++) {
+	    do {
+		sym = it.next();
+	    } while (sym.kind != VAL || (sym.flags & CASE) == 0);
+	}
+	//System.out.println(this + ", case field[" + index + "] = " + sym);//DEBUG
+	assert sym != null : this;
+	return sym;
+    }
+}
+
+/** A class for error symbols.
+ */
+public final class ErrorSymbol extends Symbol {
+
+    /** Constructor */
+    public ErrorSymbol() {
+        super(Kinds.ERROR, Position.NOPOS, Name.fromString("<error>"), null,
+	      INITIALIZED);
+        this.setOwner(this);
+        this.setInfo(Type.ErrorType);
+    }
+
+    public Symbol cloneSymbol() {
+	return this;
+    }
+
+    /** Set the mangled name of this Symbol */
+    public Symbol mangled(Name name) {
+        return this;
+    }
+
+    /** Set owner */
+    public Symbol setOwner(Symbol owner) {
+        if (owner != this)
+            throw new ApplicationError("illegal operation on " + getClass());
+        return super.setOwner(owner);
+    }
+
+    /** Set type */
+    public Symbol setInfo(Type info) {
+        if (info != Type.ErrorType)
+            throw new ApplicationError("illegal operation on " + getClass());
+        return super.setInfo(info);
+    }
+
+    /** Get primary constructor */
+    public Symbol constructor() {
+	return TermSymbol.newConstructor(this, 0).setInfo(Type.ErrorType);
+    }
+
+    /** Return the next enclosing class */
+    public Symbol enclClass() {
+        return this;
+    }
+}
+
+/** The class of Symbol.NONE
+ */
+public final class NoSymbol extends Symbol {
+
+    /** Constructor */
+    public NoSymbol() {
+        super(Kinds.NONE, Position.NOPOS, Name.fromString("<none>"), null, INITIALIZED);
+        this.setInfo(Type.NoType);
+        this.setOwner(this);
+    }
+
+    /** Return a fresh symbol with the same fields as this one.
+     */
+    public Symbol cloneSymbol() {
+        return this;
+    }
+
+    /** Set the mangled name of this Symbol */
+    public Symbol mangled(Name name) {
+        throw new ApplicationError("illegal operation on " + getClass());
+    }
+
+    /** Set owner */
+    public Symbol setOwner(Symbol owner) {
+        if (owner != this)
+            throw new ApplicationError("illegal operation on " + getClass());
+        return super.setOwner(owner);
+    }
+
+    /** Set type */
+    public Symbol setInfo(Type info) {
+        if (info != Type.NoType)
+            throw new ApplicationError("illegal operation on " + getClass());
+        return super.setInfo(info);
+    }
+
+    /** Return the next enclosing class */
+    public Symbol enclClass() {
+        return this;
+    }
+
+    public Symbol owner() {
+	throw new ApplicationError();
+    }
+}
+
+/** A class for symbols generated in label definitions.
+ */
+public class LabelSymbol extends TermSymbol {
+
+    /** give as argument the symbol of the function that triggered
+	the creation of this label */
+    public LabelSymbol(Symbol f) {
+	super(f.pos, f.name, f, LABEL);
+    }
+}
+
+/** An exception for signalling cyclic references.
+ */
+public class CyclicReference extends Type.Error {
+    public Symbol sym;
+    public Type info;
+    public CyclicReference(Symbol sym, Type info) {
+	super("illegal cyclic reference involving " + sym);
+	this.sym = sym;
+	this.info = info;
+    }
+}
+
+/** A class for types indexed by phase numbers.
+ */
+class TypeIntervalList {
+    int limit;
+    Type info;
+    TypeIntervalList prev;
+    TypeIntervalList(TypeIntervalList prev) {
+	this.prev = prev;
+    }
+    static TypeIntervalList EMPTY = new TypeIntervalList(null);
+
+  static {
+	EMPTY.limit = -1;
+    }
+}
+
+/** A class for closures indexed by phase numbers.
+ */
+class ClosureIntervalList {
+    int limit;
+    Type[] closure;
+    ClosureIntervalList prev;
+    ClosureIntervalList(ClosureIntervalList prev) {
+	this.prev = prev;
+    }
+    static ClosureIntervalList EMPTY = new ClosureIntervalList(null);
+    static {
+	EMPTY.limit = -1;
+    }
+}
+
-- 
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