Intersecting number wheels: Difference between revisions

=={{header|Nim}}==

<lang Nim>import strutils, tables

type

ElemKind = enum eValue, eWheel

Elem = object

case kind: ElemKind

of eValue:

value: Natural

of eWheel:

name: char

Wheel = ref object

elems: seq[Elem]

index: Natural

Wheels = Table[char, Wheel]

WheelDescription = tuple[name: char; elems: string]

func initWheels(wheels: openArray[WheelDescription]): Wheels =

## Initialize a table of wheels from an array of wheel descriptions.

for (name, elems) in wheels:

let wheel = new(Wheel)

for e in elems.splitWhitespace():

if e[0].isUpperAscii():

wheel.elems.add Elem(kind: eWheel, name: e[0])

else:

wheel.elems.add Elem(kind: eValue, value: e.parseInt())

result[name] = wheel

func next(wheels: Wheels; name: char): Natural =

## Return the next element from a wheel.

let wheel = wheels[name]

let elem = wheel.elems[wheel.index]

wheel.index = (wheel.index + 1) mod wheel.elems.len

result = case elem.kind

of eValue: elem.value

of eWheel: wheels.next(elem.name)

when isMainModule:

proc generate(wheelList: openArray[WheelDescription]; count: Positive) =

## Create the wheels from their description, then display

## the first "count" values generated by wheel 'A'.

let wheels = wheelList.initWheels()

for (name, elems) in wheelList:

echo name, ": ", elems

echo "generates:"

for _ in 1..count:

stdout.write ' ', wheels.next('A')

echo '\n'

{'A': "1 2 3"}.generate(20)

{'A': "1 B 2", 'B': "3 4"}.generate(20)

{'A': "1 D D", 'D': "6 7 8"}.generate(20)

{'A': "1 B C", 'B': "3 4", 'C': "5 B"}.generate(20)</lang>

{{out}}

<pre>A: 1 2 3

generates:

1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2

A: 1 B 2

B: 3 4

generates:

1 3 2 1 4 2 1 3 2 1 4 2 1 3 2 1 4 2 1 3

A: 1 D D

D: 6 7 8

generates:

1 6 7 1 8 6 1 7 8 1 6 7 1 8 6 1 7 8 1 6

A: 1 B C

B: 3 4

C: 5 B

generates:

1 3 5 1 4 3 1 4 5 1 3 4 1 3 5 1 4 3 1 4</pre>