1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
|
/* ____ ____ ____ ____ ______ *\
** / __// __ \/ __// __ \/ ____/ 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;
}
}
|
