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Doubly-linked list/Definition: Difference between revisions
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</pre>
=={{header|M2000 Interpreter}}==
<lang M2000 Interpreter>
Module Checkit {
Form 80, 50
Class Null {}
Global Null->Null()
Class Node {
group pred, succ
dat=0
Remove {
Print "destroyed", .dat
}
class:
module Node {
.pred->Null
.succ->Null
if match("N") Then Read .dat
}
}
Class LList {
Group Head, Tail
Module PushTail(k as pointer) {
if .Tail is Null then {
.Head<=k
.Tail<=k
} else {
n=.Tail
.Tail<=k
k=>pred=n=>pred
n=>pred=k
k=>succ=n
}
}
Function RemoveTail {
n=.Tail
if n is .Head then {
.Head->Null
.Tail->Null
} Else {
.Tail<=n=>succ
.Tail=>pred=n=>pred
n=>pred->Null
}
for n {
.succ->Null
.pred->Null
}
=n
}
Module PushHead(k as pointer) {
if .head is Null then {
.Head<=k
.Tail<=k
} else {
n=.head
.head<=k
k=>succ=n=>succ
n=>succ=k
k=>pred=n
}
}
Function RemoveHead {
n=.Head
if n is .Tail then {
.Head->Null
.Tail->Null
} Else {
.Head<=n=>pred
.Head=>succ=n=>succ
n=>succ->Null
}
for n {
.succ->Null
.pred->Null
}
=n
}
Module RemoveNode(k as pointer) {
pred=k=>pred
succ=k=>succ
if pred is succ then {
if .head is k else Error "Can't remove this node"
k=.RemoveJead()
clear k
} else {
pred=>succ=succ
succ=>pred=pred
}
}
Module InsertAfter(k as pointer, n as pointer) {
pred=k=>pred
n=>pred=pred
n=>succ=k
pred=>succ=n
k=>pred=n
}
Function IsEmpty {
= .Head is null or .tail is null
}
class:
Module LList {
.Head->Null
.Tail->Null
}
}
m->Node(100)
L=LList()
L.PushTail m
If not L.Head is Null then Print L.Head=>dat=100
for i=101 to 103 {
m->Node(i)
L.PushTail m
Print "ok....", i
}
for i=104 to 106 {
m->Node(i)
L.PushHead m
Print "ok....", i
}
Print "Use Head to display from last to first"
m=L.Head
do {
Print m=>dat
m=m=>pred
} Until m is null
Print "ok, now find 3rd and remove it"
m1=L.Head
i=1
Index=3
While i<Index {
if m1 is null then exit
m1=m1=>pred
i++
}
If i<>Index then {
Print "List has less than "; Index;" Items"
} Else {
Print "First add one new node"
newNode->Node(1000)
L.InsertAfter m1, newNode
L.RemoveNode m1
clear m1 ' last time m used here
newNode=Null
Print "ok.............."
}
Print "Use Tail to display from first to last"
m=L.Tail
do {
Print m=>dat
m=m=>succ
} Until m is null
useother=True
While not L.IsEmpty(){
For This {
\\ we have to use a temporary variable name, here A
A=If(useother->L.RemoveTail(),L.RemoveHead())
? A=>dat
useother~
\\ now we can try to perform removing
clear A
}
}
Print "list is empty:"; L.IsEmpty()
}
Checkit
</lang>
=={{header|Nim}}==
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