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<pre id='vimCodeElement'>
<span class="Comment"># A doubly linked list permits bidirectional traversal.</span>
container duplex-list [
value:location
next:address:duplex-list
prev:address:duplex-list
]
<span class="Comment"># result:address:duplex-list <- push-duplex x:location, in:address:duplex-list</span>
<span class="muRecipe">recipe</span> push-duplex [
<span class="Constant">default-space</span>:address:array:location<span class="Special"> <- </span>new location:type, <span class="Constant">30:literal</span>
x:location<span class="Special"> <- </span><span class="Constant">next-ingredient</span>
in:address:duplex-list<span class="Special"> <- </span><span class="Constant">next-ingredient</span>
result:address:duplex-list<span class="Special"> <- </span>new duplex-list:type
val:address:location<span class="Special"> <- </span>get-address result:address:duplex-list/deref, value:offset
val:address:location/deref<span class="Special"> <- </span>copy x:location
next:address:address:duplex-list<span class="Special"> <- </span>get-address result:address:duplex-list/deref, next:offset
next:address:address:duplex-list/deref<span class="Special"> <- </span>copy in:address:duplex-list
<span class="muControl">reply-unless</span> in:address:duplex-list, result:address:duplex-list
prev:address:address:duplex-list<span class="Special"> <- </span>get-address in:address:duplex-list/deref, prev:offset
prev:address:address:duplex-list/deref<span class="Special"> <- </span>copy result:address:duplex-list
<span class="muControl">reply</span> result:address:duplex-list
]
<span class="Comment"># result:location <- first-duplex in:address:duplex-list</span>
<span class="muRecipe">recipe</span> first-duplex [
<span class="Constant">default-space</span>:address:array:location<span class="Special"> <- </span>new location:type, <span class="Constant">30:literal</span>
in:address:duplex-list<span class="Special"> <- </span><span class="Constant">next-ingredient</span>
<span class="muControl">reply-unless</span> in:address:duplex-list, <span class="Constant">0:literal</span>
result:location<span class="Special"> <- </span>get in:address:duplex-list/deref, value:offset
<span class="muControl">reply</span> result:location
]
<span class="Comment"># result:address:duplex-list <- next-duplex in:address:duplex-list</span>
<span class="muRecipe">recipe</span> next-duplex [
<span class="Constant">default-space</span>:address:array:location<span class="Special"> <- </span>new location:type, <span class="Constant">30:literal</span>
in:address:duplex-list<span class="Special"> <- </span><span class="Constant">next-ingredient</span>
<span class="muControl">reply-unless</span> in:address:duplex-list, <span class="Constant">0:literal</span>
result:address:duplex-list<span class="Special"> <- </span>get in:address:duplex-list/deref, next:offset
<span class="muControl">reply</span> result:address:duplex-list
]
<span class="Comment"># result:address:duplex-list <- prev-duplex in:address:duplex-list</span>
<span class="muRecipe">recipe</span> prev-duplex [
<span class="Constant">default-space</span>:address:array:location<span class="Special"> <- </span>new location:type, <span class="Constant">30:literal</span>
in:address:duplex-list<span class="Special"> <- </span><span class="Constant">next-ingredient</span>
<span class="muControl">reply-unless</span> in:address:duplex-list, <span class="Constant">0:literal</span>
result:address:duplex-list<span class="Special"> <- </span>get in:address:duplex-list/deref, prev:offset
<span class="muControl">reply</span> result:address:duplex-list
]
<span class="muScenario">scenario</span> duplex-list-handling [
run [
<span class="Comment"># reserve locations 0, 1 and 2 to check for missing null check</span>
1:number<span class="Special"> <- </span>copy <span class="Constant">34:literal</span>
2:number<span class="Special"> <- </span>copy <span class="Constant">35:literal</span>
3:address:duplex-list<span class="Special"> <- </span>copy <span class="Constant">0:literal</span>
3:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">3:literal</span>, 3:address:duplex-list
3:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">4:literal</span>, 3:address:duplex-list
3:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">5:literal</span>, 3:address:duplex-list
4:address:duplex-list<span class="Special"> <- </span>copy 3:address:duplex-list
5:number<span class="Special"> <- </span>first 4:address:duplex-list
4:address:duplex-list<span class="Special"> <- </span>next-duplex 4:address:duplex-list
6:number<span class="Special"> <- </span>first 4:address:duplex-list
4:address:duplex-list<span class="Special"> <- </span>next-duplex 4:address:duplex-list
7:number<span class="Special"> <- </span>first 4:address:duplex-list
8:address:duplex-list<span class="Special"> <- </span>next-duplex 4:address:duplex-list
9:number<span class="Special"> <- </span>first 8:address:duplex-list
10:address:duplex-list<span class="Special"> <- </span>next-duplex 8:address:duplex-list
11:address:duplex-list<span class="Special"> <- </span>prev-duplex 8:address:duplex-list
4:address:duplex-list<span class="Special"> <- </span>prev-duplex 4:address:duplex-list
12:number<span class="Special"> <- </span>first 4:address:duplex-list
4:address:duplex-list<span class="Special"> <- </span>prev-duplex 4:address:duplex-list
13:number<span class="Special"> <- </span>first 4:address:duplex-list
14:boolean<span class="Special"> <- </span>equal 3:address:duplex-list, 4:address:duplex-list
<span class="CommentedCode">#? $dump-trace #? 1</span>
]
memory-should-contain [
0<span class="Special"> <- </span>0 <span class="Comment"># no modifications to null pointers</span>
1<span class="Special"> <- </span>34
2<span class="Special"> <- </span>35
5<span class="Special"> <- </span>5 <span class="Comment"># scanning next</span>
6<span class="Special"> <- </span>4
7<span class="Special"> <- </span>3
8<span class="Special"> <- </span>0 <span class="Comment"># null</span>
9<span class="Special"> <- </span>0 <span class="Comment"># first of null</span>
10<span class="Special"> <- </span>0 <span class="Comment"># next of null</span>
11<span class="Special"> <- </span>0 <span class="Comment"># prev of null</span>
12<span class="Special"> <- </span>4 <span class="Comment"># then start scanning prev</span>
13<span class="Special"> <- </span>5
14<span class="Special"> <- </span>1 <span class="Comment"># list back at start</span>
]
]
<span class="Comment"># l:address:duplex-list <- insert-duplex x:location, in:address:duplex-list</span>
<span class="Comment"># Inserts 'x' after 'in'. Returns some pointer into the list.</span>
<span class="muRecipe">recipe</span> insert-duplex [
<span class="Constant">default-space</span>:address:array:location<span class="Special"> <- </span>new location:type, <span class="Constant">30:literal</span>
x:location<span class="Special"> <- </span><span class="Constant">next-ingredient</span>
in:address:duplex-list<span class="Special"> <- </span><span class="Constant">next-ingredient</span>
new-node:address:duplex-list<span class="Special"> <- </span>new duplex-list:type
val:address:location<span class="Special"> <- </span>get-address new-node:address:duplex-list/deref, value:offset
val:address:location/deref<span class="Special"> <- </span>copy x:location
next-node:address:duplex-list<span class="Special"> <- </span>get in:address:duplex-list/deref, next:offset
<span class="Comment"># in.next = new-node</span>
y:address:address:duplex-list<span class="Special"> <- </span>get-address in:address:duplex-list/deref, next:offset
y:address:address:duplex-list/deref<span class="Special"> <- </span>copy new-node:address:duplex-list
<span class="Comment"># new-node.prev = in</span>
y:address:address:duplex-list<span class="Special"> <- </span>get-address new-node:address:duplex-list/deref, prev:offset
y:address:address:duplex-list/deref<span class="Special"> <- </span>copy in:address:duplex-list
<span class="Comment"># new-node.next = next-node</span>
y:address:address:duplex-list<span class="Special"> <- </span>get-address new-node:address:duplex-list/deref, next:offset
y:address:address:duplex-list/deref<span class="Special"> <- </span>copy next-node:address:duplex-list
<span class="Comment"># if next-node is not null</span>
<span class="muControl">reply-unless</span> next-node:address:duplex-list, new-node:address:duplex-list
<span class="Comment"># next-node.prev = new-node</span>
y:address:address:duplex-list<span class="Special"> <- </span>get-address next-node:address:duplex-list/deref, prev:offset
y:address:address:duplex-list/deref<span class="Special"> <- </span>copy new-node:address:duplex-list
<span class="muControl">reply</span> new-node:address:duplex-list <span class="Comment"># just signalling something changed; don't rely on the result</span>
]
<span class="muScenario">scenario</span> inserting-into-duplex-list [
run [
1:address:duplex-list<span class="Special"> <- </span>copy <span class="Constant">0:literal</span> <span class="Comment"># 1 points to head of list</span>
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">3:literal</span>, 1:address:duplex-list
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">4:literal</span>, 1:address:duplex-list
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">5:literal</span>, 1:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>next-duplex 1:address:duplex-list <span class="Comment"># 2 points inside list</span>
2:address:duplex-list<span class="Special"> <- </span>insert-duplex <span class="Constant">6:literal</span>, 2:address:duplex-list
<span class="Comment"># check structure like before</span>
2:address:duplex-list<span class="Special"> <- </span>copy 1:address:duplex-list
3:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>next-duplex 2:address:duplex-list
4:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>next-duplex 2:address:duplex-list
5:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>next-duplex 2:address:duplex-list
6:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>prev-duplex 2:address:duplex-list
7:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>prev-duplex 2:address:duplex-list
8:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>prev-duplex 2:address:duplex-list
9:number<span class="Special"> <- </span>first 2:address:duplex-list
10:boolean<span class="Special"> <- </span>equal 1:address:duplex-list, 2:address:duplex-list
]
memory-should-contain [
3<span class="Special"> <- </span>5 <span class="Comment"># scanning next</span>
4<span class="Special"> <- </span>4
5<span class="Special"> <- </span>6 <span class="Comment"># inserted element</span>
6<span class="Special"> <- </span>3
7<span class="Special"> <- </span>6 <span class="Comment"># then prev</span>
8<span class="Special"> <- </span>4
9<span class="Special"> <- </span>5
10<span class="Special"> <- </span>1 <span class="Comment"># list back at start</span>
]
]
<span class="muScenario">scenario</span> inserting-at-end-of-duplex-list [
run [
1:address:duplex-list<span class="Special"> <- </span>copy <span class="Constant">0:literal</span> <span class="Comment"># 1 points to head of list</span>
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">3:literal</span>, 1:address:duplex-list
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">4:literal</span>, 1:address:duplex-list
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">5:literal</span>, 1:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>next-duplex 1:address:duplex-list <span class="Comment"># 2 points inside list</span>
2:address:duplex-list<span class="Special"> <- </span>next-duplex 2:address:duplex-list <span class="Comment"># now at end of list</span>
2:address:duplex-list<span class="Special"> <- </span>insert-duplex <span class="Constant">6:literal</span>, 2:address:duplex-list
<span class="Comment"># check structure like before</span>
2:address:duplex-list<span class="Special"> <- </span>copy 1:address:duplex-list
3:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>next-duplex 2:address:duplex-list
4:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>next-duplex 2:address:duplex-list
5:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>next-duplex 2:address:duplex-list
6:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>prev-duplex 2:address:duplex-list
7:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>prev-duplex 2:address:duplex-list
8:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>prev-duplex 2:address:duplex-list
9:number<span class="Special"> <- </span>first 2:address:duplex-list
10:boolean<span class="Special"> <- </span>equal 1:address:duplex-list, 2:address:duplex-list
]
memory-should-contain [
3<span class="Special"> <- </span>5 <span class="Comment"># scanning next</span>
4<span class="Special"> <- </span>4
5<span class="Special"> <- </span>3
6<span class="Special"> <- </span>6 <span class="Comment"># inserted element</span>
7<span class="Special"> <- </span>3 <span class="Comment"># then prev</span>
8<span class="Special"> <- </span>4
9<span class="Special"> <- </span>5
10<span class="Special"> <- </span>1 <span class="Comment"># list back at start</span>
]
]
<span class="muScenario">scenario</span> inserting-after-start-of-duplex-list [
run [
1:address:duplex-list<span class="Special"> <- </span>copy <span class="Constant">0:literal</span> <span class="Comment"># 1 points to head of list</span>
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">3:literal</span>, 1:address:duplex-list
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">4:literal</span>, 1:address:duplex-list
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">5:literal</span>, 1:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>insert-duplex <span class="Constant">6:literal</span>, 1:address:duplex-list
<span class="Comment"># check structure like before</span>
2:address:duplex-list<span class="Special"> <- </span>copy 1:address:duplex-list
3:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>next-duplex 2:address:duplex-list
4:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>next-duplex 2:address:duplex-list
5:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>next-duplex 2:address:duplex-list
6:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>prev-duplex 2:address:duplex-list
7:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>prev-duplex 2:address:duplex-list
8:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>prev-duplex 2:address:duplex-list
9:number<span class="Special"> <- </span>first 2:address:duplex-list
10:boolean<span class="Special"> <- </span>equal 1:address:duplex-list, 2:address:duplex-list
]
memory-should-contain [
3<span class="Special"> <- </span>5 <span class="Comment"># scanning next</span>
4<span class="Special"> <- </span>6 <span class="Comment"># inserted element</span>
5<span class="Special"> <- </span>4
6<span class="Special"> <- </span>3
7<span class="Special"> <- </span>4 <span class="Comment"># then prev</span>
8<span class="Special"> <- </span>6
9<span class="Special"> <- </span>5
10<span class="Special"> <- </span>1 <span class="Comment"># list back at start</span>
]
]
<span class="Comment"># l:address:duplex-list <- remove-duplex in:address:duplex-list</span>
<span class="Comment"># Removes 'in' from its surrounding list. Returns some valid pointer into the</span>
<span class="Comment"># rest of the list.</span>
<span class="Comment">#</span>
<span class="Comment"># Returns null if and only if list is empty. Beware: in that case any pointers</span>
<span class="Comment"># to the head are now invalid.</span>
<span class="muRecipe">recipe</span> remove-duplex [
<span class="Constant">default-space</span>:address:array:location<span class="Special"> <- </span>new location:type, <span class="Constant">30:literal</span>
in:address:duplex-list<span class="Special"> <- </span><span class="Constant">next-ingredient</span>
<span class="Comment"># if 'in' is null, return</span>
<span class="muControl">reply-unless</span> in:address:duplex-list, in:address:duplex-list
next-node:address:duplex-list<span class="Special"> <- </span>get in:address:duplex-list/deref, next:offset
prev-node:address:duplex-list<span class="Special"> <- </span>get in:address:duplex-list/deref, prev:offset
<span class="Comment"># null in's pointers</span>
x:address:address:duplex-list<span class="Special"> <- </span>get-address in:address:duplex-list/deref, next:offset
x:address:address:duplex-list/deref<span class="Special"> <- </span>copy <span class="Constant">0:literal</span>
x:address:address:duplex-list<span class="Special"> <- </span>get-address in:address:duplex-list/deref, prev:offset
x:address:address:duplex-list/deref<span class="Special"> <- </span>copy <span class="Constant">0:literal</span>
<span class="Delimiter">{</span>
<span class="Comment"># if next-node is not null</span>
<span class="muControl">break-unless</span> next-node:address:duplex-list
<span class="Comment"># next-node.prev = prev-node</span>
x:address:address:duplex-list<span class="Special"> <- </span>get-address next-node:address:duplex-list/deref, prev:offset
x:address:address:duplex-list/deref<span class="Special"> <- </span>copy prev-node:address:duplex-list
<span class="Delimiter">}</span>
<span class="Delimiter">{</span>
<span class="Comment"># if prev-node is not null</span>
<span class="muControl">break-unless</span> prev-node:address:duplex-list
<span class="Comment"># prev-node.next = next-node</span>
x:address:address:duplex-list<span class="Special"> <- </span>get-address prev-node:address:duplex-list/deref, next:offset
x:address:address:duplex-list/deref<span class="Special"> <- </span>copy next-node:address:duplex-list
<span class="muControl">reply</span> prev-node:address:duplex-list
<span class="Delimiter">}</span>
<span class="muControl">reply</span> next-node:address:duplex-list
]
<span class="muScenario">scenario</span> removing-from-duplex-list [
run [
1:address:duplex-list<span class="Special"> <- </span>copy <span class="Constant">0:literal</span> <span class="Comment"># 1 points to head of list</span>
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">3:literal</span>, 1:address:duplex-list
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">4:literal</span>, 1:address:duplex-list
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">5:literal</span>, 1:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>next-duplex 1:address:duplex-list <span class="Comment"># 2 points at second element</span>
2:address:duplex-list<span class="Special"> <- </span>remove-duplex 2:address:duplex-list
3:boolean<span class="Special"> <- </span>equal 2:address:duplex-list, <span class="Constant">0:literal</span>
<span class="Comment"># check structure like before</span>
2:address:duplex-list<span class="Special"> <- </span>copy 1:address:duplex-list
4:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>next-duplex 2:address:duplex-list
5:number<span class="Special"> <- </span>first 2:address:duplex-list
6:address:duplex-list<span class="Special"> <- </span>next-duplex 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>prev-duplex 2:address:duplex-list
7:number<span class="Special"> <- </span>first 2:address:duplex-list
8:boolean<span class="Special"> <- </span>equal 1:address:duplex-list, 2:address:duplex-list
]
memory-should-contain [
3<span class="Special"> <- </span>0 <span class="Comment"># remove returned non-null</span>
4<span class="Special"> <- </span>5 <span class="Comment"># scanning next, skipping deleted element</span>
5<span class="Special"> <- </span>3
6<span class="Special"> <- </span>0 <span class="Comment"># no more elements</span>
7<span class="Special"> <- </span>5 <span class="Comment"># prev of final element</span>
8<span class="Special"> <- </span>1 <span class="Comment"># list back at start</span>
]
]
<span class="muScenario">scenario</span> removing-from-start-of-duplex-list [
run [
1:address:duplex-list<span class="Special"> <- </span>copy <span class="Constant">0:literal</span> <span class="Comment"># 1 points to head of list</span>
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">3:literal</span>, 1:address:duplex-list
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">4:literal</span>, 1:address:duplex-list
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">5:literal</span>, 1:address:duplex-list
<span class="Comment"># removing from head? return value matters.</span>
1:address:duplex-list<span class="Special"> <- </span>remove-duplex 1:address:duplex-list
<span class="Comment"># check structure like before</span>
2:address:duplex-list<span class="Special"> <- </span>copy 1:address:duplex-list
3:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>next-duplex 2:address:duplex-list
4:number<span class="Special"> <- </span>first 2:address:duplex-list
5:address:duplex-list<span class="Special"> <- </span>next-duplex 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>prev-duplex 2:address:duplex-list
6:number<span class="Special"> <- </span>first 2:address:duplex-list
7:boolean<span class="Special"> <- </span>equal 1:address:duplex-list, 2:address:duplex-list
]
memory-should-contain [
3<span class="Special"> <- </span>4 <span class="Comment"># scanning next, skipping deleted element</span>
4<span class="Special"> <- </span>3
5<span class="Special"> <- </span>0 <span class="Comment"># no more elements</span>
6<span class="Special"> <- </span>4 <span class="Comment"># prev of final element</span>
7<span class="Special"> <- </span>1 <span class="Comment"># list back at start</span>
]
]
<span class="muScenario">scenario</span> removing-from-end-of-duplex-list [
run [
1:address:duplex-list<span class="Special"> <- </span>copy <span class="Constant">0:literal</span> <span class="Comment"># 1 points to head of list</span>
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">3:literal</span>, 1:address:duplex-list
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">4:literal</span>, 1:address:duplex-list
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">5:literal</span>, 1:address:duplex-list
<span class="Comment"># delete last element</span>
2:address:duplex-list<span class="Special"> <- </span>next-duplex 1:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>next-duplex 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>remove-duplex 2:address:duplex-list
3:boolean<span class="Special"> <- </span>equal 2:address:duplex-list, <span class="Constant">0:literal</span>
<span class="Comment"># check structure like before</span>
2:address:duplex-list<span class="Special"> <- </span>copy 1:address:duplex-list
4:number<span class="Special"> <- </span>first 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>next-duplex 2:address:duplex-list
5:number<span class="Special"> <- </span>first 2:address:duplex-list
6:address:duplex-list<span class="Special"> <- </span>next-duplex 2:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>prev-duplex 2:address:duplex-list
7:number<span class="Special"> <- </span>first 2:address:duplex-list
8:boolean<span class="Special"> <- </span>equal 1:address:duplex-list, 2:address:duplex-list
]
memory-should-contain [
3<span class="Special"> <- </span>0 <span class="Comment"># remove returned non-null</span>
4<span class="Special"> <- </span>5 <span class="Comment"># scanning next, skipping deleted element</span>
5<span class="Special"> <- </span>4
6<span class="Special"> <- </span>0 <span class="Comment"># no more elements</span>
7<span class="Special"> <- </span>5 <span class="Comment"># prev of final element</span>
8<span class="Special"> <- </span>1 <span class="Comment"># list back at start</span>
]
]
<span class="muScenario">scenario</span> removing-from-singleton-list [
run [
1:address:duplex-list<span class="Special"> <- </span>copy <span class="Constant">0:literal</span> <span class="Comment"># 1 points to singleton list</span>
1:address:duplex-list<span class="Special"> <- </span>push-duplex <span class="Constant">3:literal</span>, 1:address:duplex-list
2:address:duplex-list<span class="Special"> <- </span>remove-duplex 1:address:duplex-list
3:address:duplex-list<span class="Special"> <- </span>get 1:address:duplex-list/deref, next:offset
4:address:duplex-list<span class="Special"> <- </span>get 1:address:duplex-list/deref, prev:offset
]
memory-should-contain [
2<span class="Special"> <- </span>0 <span class="Comment"># remove returned null</span>
3<span class="Special"> <- </span>0 <span class="Comment"># removed node is also detached</span>
4<span class="Special"> <- </span>0
]
]
</pre>
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