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1 | sclass ValueOnDemandMap<A, B> extends AbstractMap<A, B> {
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2 | Set<A> keys; // keys may be changed if map is changed |
3 | IF1<A, B> makeValue; |
4 | |
5 | *() {}
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6 | *(Set<A> *keys, IF1<A, B> *makeValue) {} // doesn't clone keys
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7 | |
8 | public B get(O a) {
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9 | ret !containsKey(a) ? null : makeValue.get((A) a); |
10 | } |
11 | |
12 | public bool containsKey(O a) {
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13 | ret keys.contains(a); |
14 | } |
15 | |
16 | public Set<Map.Entry<A, B>> entrySet() {
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17 | ret new EntrySet; |
18 | } |
19 | |
20 | final class EntrySet extends AbstractSet<Map.Entry<A,B>> {
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21 | public final int size() { ret keys.size(); }
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22 | public final void clear() { keys.clear(); }
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23 | public final Iterator<Map.Entry<A,B>> iterator() {
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24 | return mapI(keys.iterator(), key -> new Map.Entry<A, B>() {
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25 | public A getKey() { ret key; }
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26 | public B getValue() { ret makeValue.get(key); }
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27 | public B setValue(B newValue) {
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28 | throw unimplemented(); |
29 | } |
30 | }); |
31 | } |
32 | public final boolean contains(Object o) {
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33 | if (o cast Map.Entry) |
34 | ret keys.contains(o.getKey()); |
35 | false; |
36 | } |
37 | public final boolean remove(Object o) {
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38 | if (o cast Map.Entry) |
39 | ret keys.remove(o.getKey()); |
40 | false; |
41 | } |
42 | } |
43 | |
44 | public Set<A> keySet() { ret keys; }
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45 | |
46 | public int size() { ret keys.size(); }
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47 | } |
Began life as a copy of #1008575
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| Snippet ID: | #1028138 |
| Snippet name: | ValueOnDemandMap - map over a key set where values are calculated on every access |
| Eternal ID of this version: | #1028138/12 |
| Text MD5: | 95661ad9b4011faa89cd994cd2fdbca1 |
| Transpilation MD5: | 1b44fe9d830feb8f1e170c857ecf974c |
| Author: | stefan |
| Category: | javax |
| Type: | JavaX fragment (include) |
| Public (visible to everyone): | Yes |
| Archived (hidden from active list): | No |
| Created/modified: | 2020-05-23 14:34:54 |
| Source code size: | 1307 bytes / 47 lines |
| Pitched / IR pitched: | No / No |
| Views / Downloads: | 265 / 619 |
| Version history: | 11 change(s) |
| Referenced in: | [show references] |