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1
4 package gnu.mapping;
5 import java.io.*;
6
7
10
11 public class SimpleEnvironment extends Environment
12 {
13 NamedLocation[] table;
14 int log2Size;
15 private int mask;
16
17 int num_bindings;
18 int currentTimestamp;
19
20
21 public int size () { return num_bindings; }
22
23 public static Location getCurrentLocation (String  name)
24 {
25 return getCurrent().getLocation(name, true);
26 }
27
28 public static Object lookup_global (Symbol name)
29 throws UnboundLocationException
30 {
31 Location binding = getCurrent().lookup(name);
32 if (binding == null)
33 throw new UnboundLocationException(name);
34 return binding.get();
35 }
36
37
38 NamedLocation sharedTail;
39
40 public SimpleEnvironment ()
41 {
42 this(64);
43 }
44
45 public SimpleEnvironment (String name)
46 {
47 this();
48 setName(name);
49 }
50
51 public SimpleEnvironment (int capacity)
52 {
53 log2Size = 4;
54 while (capacity > (1 << log2Size))
55 log2Size++;
56 capacity = 1 << log2Size;
57 table = new NamedLocation[capacity];
58 mask = capacity - 1;
59
60 sharedTail = new PlainLocation(null, null, this);
61 }
62
63 public NamedLocation lookup (Symbol name, Object property, int hash)
64 {
65 return lookupDirect(name, property, hash);
66 }
67
68 public NamedLocation lookupDirect (Symbol name, Object property, int hash)
69 {
70 int index = hash & this.mask;
71 for (NamedLocation loc = table[index];
72 loc != null; loc = loc.next)
73 {
74 if (loc.matches(name, property))
75 return loc;
76 }
77 return null;
78 }
79
80 public synchronized NamedLocation
81 getLocation (Symbol name, Object property, int hash, boolean create)
82 {
83 NamedLocation loc = lookup(name, property, hash);
84 if (loc != null)
85 return loc;
86 if (! create)
87 return null;
88 return addUnboundLocation(name, property, hash);
89 }
90
91 protected NamedLocation addUnboundLocation(Symbol name, Object property,
92 int hash)
93 {
94 int index = hash & mask;
95 NamedLocation loc = newEntry(name, property, index);
96 loc.base = null;
97 loc.value = Location.UNBOUND;
98 return loc;
99 }
100
101 public void put(Symbol key, Object property, Object newValue)
102 {
103 boolean create = (flags & CAN_IMPLICITLY_DEFINE) != 0;
104 Location loc = getLocation(key, property, create);
105 if (loc == null)
106 throw new UnboundLocationException(key);
107 else if (loc.isConstant())
108 throw new IllegalStateException ("attempt to modify read-only location: "
109 + key + " in "+this+" loc:"+loc);
110 loc.set(newValue);
111 }
112
113 NamedLocation newLocation (Symbol name, Object property)
115 {
116 if ((flags & THREAD_SAFE) != 0)
117 return new SharedLocation(name, property, currentTimestamp);
118 else
119 return new PlainLocation(name, property);
120 }
121
122 NamedLocation newEntry (Symbol name, Object property, int index)
123 {
124 NamedLocation loc = newLocation(name, property);
125 NamedLocation first = table[index];
126 loc.next = first == null ? sharedTail : first;
127 table[index] = loc;
128 num_bindings++;
129 if (num_bindings >= table.length)
130 rehash();
131 return loc;
132 }
133
134 public NamedLocation define (Symbol sym, Object property, int hash,
135 Object newValue)
136 {
137 int index = hash & mask;
138 NamedLocation first = table[index];
139 NamedLocation loc = first;
140 for (;;)
141 {
142 if (loc == null)
143 {
144 loc = newEntry(sym, property, index);
146 loc.set(newValue);
147 return loc;
148 }
149 else if (loc.matches(sym, property))
150 {
151 if (! (loc.isBound() ? getCanDefine() : getCanRedefine()))
152 redefineError(sym, property, loc);
153 loc.base = null;
154 loc.value = newValue;
155 return loc;
156 }
157 loc = loc.next;
158 }
159 }
160
161 public void define (Symbol sym, Object property, Object newValue)
162 {
163 int hash = sym.hashCode() ^ System.identityHashCode(property);
164 define(sym, property, hash, newValue);
165 }
166
167 protected void redefineError (Symbol name, Object property, Location loc)
168 {
169 throw new IllegalStateException ("prohibited define/redefine of "
170 +name+" in "+this);
171 }
172
173 public NamedLocation addLocation (Symbol name, Object property, Location loc)
174 {
175 return addLocation(name, property,
176 name.hashCode() ^ System.identityHashCode(property), loc);
177 }
178
179 NamedLocation addLocation (Symbol name, Object property, int hash, Location loc)
181 {
182 if (loc instanceof ThreadLocation
183 && ((ThreadLocation) loc).property == property)
184 loc = ((ThreadLocation) loc).getLocation();
185 NamedLocation nloc = lookupDirect(name, property, hash);
186 if (loc == nloc)
187 return nloc;
188 boolean bound = (nloc != null);
189 if (! bound)
190 nloc = addUnboundLocation(name, property, hash);
191 if ((flags & CAN_DEFINE+CAN_REDEFINE) != CAN_DEFINE+CAN_REDEFINE)
192 {
193 if (bound)
194 bound = nloc.isBound();
195 if (bound
199 ? ((flags & CAN_REDEFINE) == 0)
200 : ((flags & CAN_DEFINE) == 0) && loc.isBound());
201 redefineError(name, property, nloc);
202 }
203 if ((flags & Environment.INDIRECT_DEFINES) != 0)
204 nloc.base = ((SimpleEnvironment) ((InheritingEnvironment) this).getParent(0)).addLocation(name, property, hash, loc);
205 else
206 nloc.base = loc;
207 nloc.value = IndirectableLocation.INDIRECT_FLUIDS;
208 return nloc;
209 }
210
211 void rehash ()
212 {
213 NamedLocation[] oldTable = table;
214 int oldCapacity = oldTable.length;
215 int newCapacity = 2 * oldCapacity;
216 NamedLocation[] newTable = new NamedLocation[newCapacity];
217 int newMask = newCapacity - 1;
218 for (int i = oldCapacity; --i >= 0;)
219 {
220 for (NamedLocation element = oldTable[i];
221 element != null && element != sharedTail; )
222 {
223 NamedLocation next = element.next;
224 Symbol name = element.name;
225 Object property = element.property;
226 int hash = name.hashCode() ^ System.identityHashCode(property);
227 int j = hash & newMask;
228 NamedLocation head = newTable[j];
229 if (head == null)
230 head = sharedTail;
231 element.next = head;
232 newTable[j] = element;
233 element = next;
234 }
235 }
236 table = newTable;
237 log2Size++;
238 mask = newMask;
239 }
240
241 public Location unlink (Symbol symbol, Object property, int hash)
242 {
243 int index = hash & this.mask;
244 NamedLocation prev = null;
245 NamedLocation loc = table[index];
246 while (loc != null)
247 {
248 NamedLocation next = loc.next;
249 if (loc.matches(symbol, property))
250 {
251 if (! getCanRedefine())
252 redefineError(symbol, property, loc);
253 if (prev == null)
254 table[index] = next;
255 else
256 prev.next = loc;
257 num_bindings--;
258 return loc;
259 }
260 prev = loc;
261 loc = next;
262 }
263 return null;
264 }
265
266
267 public LocationEnumeration enumerateLocations()
268 {
269 LocationEnumeration it = new LocationEnumeration(table, 1 << log2Size);
270 it.env = this;
271 return it;
272 }
273
274
275 public LocationEnumeration enumerateAllLocations()
276 {
277 return enumerateLocations();
278 }
279
280 protected boolean hasMoreElements (LocationEnumeration it)
281 {
282 for (;;)
283 {
284 if (it.curLoc == null)
285 {
286 if (--it.index < 0)
287 return false;
288 it.curLoc = it.bindings[it.index];
289 if (it.curLoc == null)
290 continue;
291 }
292 if (it.curLoc.name == null)
293 it.curLoc = it.curLoc.next;
294 else
295 break;
296 }
297 return true;
298 }
299
300 public void writeExternal(ObjectOutput out) throws IOException
301 {
302 out.writeObject(getSymbol());
303 }
304
305 public void readExternal(ObjectInput in)
306 throws IOException, ClassNotFoundException
307 {
308 setSymbol(in.readObject());
309 }
310
311 public Object readResolve() throws ObjectStreamException
312 {
313 String name = getName();
314 Environment env = (Environment) envTable.get(name);
315 if (env != null)
316 return env;
317 envTable.put(name, this);
318 return this;
319
320 }
321
322
323 public java.util.Set entrySet ()
324 {
325 return new EnvironmentMappings(this);
326 }
327
328
329 public String toStringVerbose ()
330 {
331 StringBuffer sbuf = new StringBuffer ();
332 toStringBase(sbuf);
333 return "#<environment "+getName()+" num:"+num_bindings
334 +" ts:"+currentTimestamp+sbuf+'>';
335 }
336
337 protected void toStringBase (StringBuffer sbuf) { ; }
338 }
339
340
341 class EnvironmentMappings
342 extends java.util.AbstractSet
343 {
344 SimpleEnvironment env;
345
346 public EnvironmentMappings (SimpleEnvironment env) { this.env = env; }
347
348 public int size() { return env.size(); }
349
350 public java.util.Iterator iterator ()
351 {
352 return new LocationEnumeration(env);
353 }
354 }
355
356 |
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