/* ____ ____ ____ ____ ______ *\
** / __// __ \/ __// __ \/ ____/ SOcos COmpiles Scala **
** __\_ \/ /_/ / /__/ /_/ /\_ \ (c) 2002, LAMP/EPFL **
** /_____/\____/\___/\____/____/ **
\* */
package scalac.typechecker;
import java.util.HashMap;
import scalac.*;
import scalac.util.*;
import scalac.ast.*;
import scalac.symtab.*;
import Tree.*;
/** Check that no forward reference to a term symbol extends beyond a value definition.
*/
public class RefCheck extends Transformer implements Modifiers, Kinds {
public RefCheck(Global global) {
super(global);
}
private Unit unit;
private Scope[] scopes = new Scope[4];
private int[] maxindex = new int[4];
private int[] refpos = new int[4];
private Symbol[] refsym = new Symbol[4];
private int level;
private HashMap symIndex = new HashMap();
void pushLevel() {
level++;
if (level == scopes.length) {
Scope[] scopes1 = new Scope[scopes.length * 2];
int[] maxindex1 = new int[scopes.length * 2];
int[] refpos1 = new int[scopes.length * 2];
Symbol[] refsym1 = new Symbol[scopes.length * 2];
System.arraycopy(scopes, 0, scopes1, 0, scopes.length);
System.arraycopy(maxindex, 0, maxindex1, 0, scopes.length);
System.arraycopy(refpos, 0, refpos1, 0, scopes.length);
System.arraycopy(refsym, 0, refsym1, 0, scopes.length);
scopes = scopes1;
maxindex = maxindex1;
refpos = refpos1;
refsym = refsym1;
}
scopes[level] = new Scope(scopes[level - 1]);
maxindex[level] = Integer.MIN_VALUE;
}
void popLevel() {
scopes[level] = null;
level --;
}
public void apply(Unit unit) {
this.unit = unit;
level = 0;
scopes[0] = new Scope();
maxindex[0] = Integer.MIN_VALUE;
unit.body = transformStats(unit.body);
scopes[0] = null;
symIndex.clear();
}
/** compensate for renaming during addition of access functions
*/
Name normalize(Name name) {
return (name.endsWith(Name.fromString("$")))
? name.subName(0, name.length() - 1)
: name;
}
void enterSyms(Tree[] stats) {
for (int i = 0; i < stats.length; i++) {
enterSym(stats[i], i);
}
}
void enterSym(Tree stat, int index) {
Symbol sym = null;
switch (stat) {
case ClassDef(_, _, _, _, _, _):
sym = stat.symbol().constructor();
break;
case DefDef(_, _, _, _, _, _):
case ModuleDef(_, _, _, _):
case ValDef(_, _, _, _):
sym = stat.symbol();
}
if (sym != null && sym.isLocal()) {
scopes[level].enter(sym);
symIndex.put(sym, new Integer(index));
}
}
public Tree[] transformStats(Tree[] stats) {
pushLevel();
enterSyms(stats);
int i = 0;
while (i < stats.length) {
Tree[] newstat = transformStat(stats[i], i);
if (newstat != null) {
Tree[] newstats = new Tree[stats.length + newstat.length - 1];
System.arraycopy(stats, 0, newstats, 0, i);
System.arraycopy(newstat, 0, newstats, i, newstat.length);
System.arraycopy(stats, i + 1, newstats, i + newstat.length,
stats.length - i - 1);
i = i + newstat.length;
stats = newstats;
} else {
i = i + 1;
}
}
popLevel();
return stats;
}
public Tree nullTree(int pos, Type tp) {
return gen.TypeApply(
gen.Ident(pos, global.definitions.NULL),
new Tree[]{gen.mkType(pos, tp)});
}
private boolean isGlobalModule(Symbol sym) {
return
sym.isModule() &&
(sym.owner().isPackage() || isGlobalModule(sym.owner().module()));
}
/** The main checking functions
*/
public Tree[] transformStat(Tree tree, int index) {
Tree resultTree;
switch (tree) {
case ModuleDef(int mods, Name name, Tree tpe, Tree.Template templ):
Symbol sym = tree.symbol();
Tree cdef = make.ClassDef(
tree.pos,
mods | FINAL | MODUL,
name.toTypeName(),
Tree.ExtTypeDef.EMPTY_ARRAY,
Tree.ExtValDef.EMPTY_ARRAY_ARRAY,
Tree.Empty,
templ)
.setSymbol(sym.moduleClass()).setType(tree.type);
Tree alloc = gen.New(
tree.pos,
sym.type().prefix(),
sym.moduleClass(),
Tree.EMPTY_ARRAY);
Tree[] result;
if (isGlobalModule(sym)) {
Tree vdef = gen.ValDef(sym, alloc);
result = new Tree[]{cdef, vdef};
} else {
// var m$: T = null[T];
Name varname = Name.fromString(name + "$");
Symbol mvar = new TermSymbol(
tree.pos, varname, sym.owner(), PRIVATE | MUTABLE | SYNTHETIC)
.setInfo(sym.type());
Tree vdef = gen.ValDef(mvar, nullTree(tree.pos, sym.type()));
// { if (m$ == null[T]) m$ = new m$class; m$ }
Tree body = gen.Block(new Tree[]{
gen.If(
gen.Apply(
gen.Select(gen.mkRef(tree.pos, mvar), global.definitions.EQEQ),
new Tree[]{nullTree(tree.pos, sym.type())}),
gen.Assign(gen.mkRef(tree.pos, mvar), alloc),
gen.Block(tree.pos, Tree.EMPTY_ARRAY)),
gen.mkRef(tree.pos, mvar)});
// def m: T = { if (m$ == null[T]) m$ = new m$class; m$ }
sym.updateInfo(Type.PolyType(Symbol.EMPTY_ARRAY, sym.type()));
sym.flags |= STABLE;
Tree ddef = gen.DefDef(sym, body);
result = new Tree[]{cdef, vdef, ddef};
}
return transform(result);
case ValDef(int mods, Name name, Tree tpe, Tree rhs):
Symbol sym = tree.symbol();
resultTree = transform(tree);
//todo: handle variables
if (sym.isLocal() && !sym.isModule() && index <= maxindex[level]) {
if (Global.instance.debug)
System.out.println(refsym[level] + ":" + refsym[level].type());
unit.error(
refpos[level],
"forward reference extends over definition of value " +
normalize(name));
}
break;
default:
resultTree = transform(tree);
}
return (resultTree == tree) ? null : new Tree[]{resultTree};
}
public Tree transform(Tree tree) {
Tree tree1;
switch (tree) {
case Template(Tree[] bases, Tree[] body):
Tree[] bases1 = transform(bases);
Tree[] body1 = transformStats(body);
return copy.Template(tree, bases1, body1);
case Block(Tree[] stats):
Tree[] stats1 = transformStats(stats);
return copy.Block(tree, stats1);
case This(_):
return tree;
case PackageDef(Tree pkg, Template packaged):
return copy.PackageDef(tree, pkg, super.transform(packaged));
case Ident(Name name):
Scope.Entry e = scopes[level].lookupEntry(name);
Symbol sym = tree.symbol();
assert sym != null : name;
if (sym.isLocal() && sym == e.sym) {
int i = level;
while (scopes[i] != e.owner) i--;
int symindex = ((Integer) symIndex.get(tree.symbol())).intValue();
if (maxindex[i] < symindex) {
refpos[i] = tree.pos;
refsym[i] = e.sym;
maxindex[i] = symindex;
}
}
tree1 = tree;
break;
default:
tree1 = super.transform(tree);
}
if (tree1.isType() && !tree1.isMissing())
tree1 = gen.mkType(tree1.pos, tree1.type);
return tree1;
}
}
