discard """
output: '''true'''
"""
import hashes, math
when defined(shallowADT):
{.pragma: myShallow, shallow.}
else:
{.pragma: myShallow.}
type
TSlotEnum = enum seEmpty, seFilled, seDeleted
TKeyValuePair[A, B] = tuple[slot: TSlotEnum, key: A, val: B]
TKeyValuePairSeq[A, B] = seq[TKeyValuePair[A, B]]
TTable* {.final, myShallow.}[A, B] = object
data: TKeyValuePairSeq[A, B]
counter: int
proc len*[A, B](t: TTable[A, B]): int =
## returns the number of keys in `t`.
result = t.counter
iterator pairs*[A, B](t: TTable[A, B]): tuple[key: A, val: B] =
## iterates over any (key, value) pair in the table `t`.
for h in 0..high(t.data):
if t.data[h].slot == seFilled: yield (t.data[h].key, t.data[h].val)
iterator keys*[A, B](t: TTable[A, B]): A =
## iterates over any key in the table `t`.
for h in 0..high(t.data):
if t.data[h].slot == seFilled: yield t.data[h].key
iterator values*[A, B](t: TTable[A, B]): B =
## iterates over any value in the table `t`.
for h in 0..high(t.data):
if t.data[h].slot == seFilled: yield t.data[h].val
const
growthFactor = 2
proc mustRehash(length, counter: int): bool {.inline.} =
assert(length > counter)
result = (length * 2 < counter * 3) or (length - counter < 4)
proc nextTry(h, maxHash: THash): THash {.inline.} =
result = ((5 * h) + 1) and maxHash
template rawGetImpl() =
var h: THash = hash(key) and high(t.data) # start with real hash value
while t.data[h].slot != seEmpty:
if t.data[h].key == key and t.data[h].slot == seFilled:
return h
h = nextTry(h, high(t.data))
result = -1
template rawInsertImpl() =
var h: THash = hash(key) and high(data)
while data[h].slot == seFilled:
h = nextTry(h, high(data))
data[h].key = key
data[h].val = val
data[h].slot = seFilled
proc RawGet[A, B](t: TTable[A, B], key: A): int =
rawGetImpl()
proc `[]`*[A, B](t: TTable[A, B], key: A): B =
## retrieves the value at ``t[key]``. If `key` is not in `t`,
## default empty value for the type `B` is returned
## and no exception is raised. One can check with ``hasKey`` whether the key
## exists.
var index = RawGet(t, key)
if index >= 0: result = t.data[index].val
proc hasKey*[A, B](t: TTable[A, B], key: A): bool =
## returns true iff `key` is in the table `t`.
result = rawGet(t, key) >= 0
proc RawInsert[A, B](t: var TTable[A, B], data: var TKeyValuePairSeq[A, B],
key: A, val: B) =
rawInsertImpl()
proc Enlarge[A, B](t: var TTable[A, B]) =
var n: TKeyValuePairSeq[A, B]
newSeq(n, len(t.data) * growthFactor)
for i in countup(0, high(t.data)):
if t.data[i].slot == seFilled: RawInsert(t, n, t.data[i].key, t.data[i].val)
swap(t.data, n)
template PutImpl() =
var index = RawGet(t, key)
if index >= 0:
t.data[index].val = val
else:
if mustRehash(len(t.data), t.counter): Enlarge(t)
RawInsert(t, t.data, key, val)
inc(t.counter)
proc `[]=`*[A, B](t: var TTable[A, B], key: A, val: B) =
## puts a (key, value)-pair into `t`.
putImpl()
proc del*[A, B](t: var TTable[A, B], key: A) =
## deletes `key` from hash table `t`.
var index = RawGet(t, key)
if index >= 0:
t.data[index].slot = seDeleted
dec(t.counter)
proc initTable*[A, B](initialSize=64): TTable[A, B] =
## creates a new hash table that is empty. `initialSize` needs to be
## a power of two.
assert isPowerOfTwo(initialSize)
result.counter = 0
newSeq(result.data, initialSize)
proc toTable*[A, B](pairs: openarray[tuple[key: A,
val: B]]): TTable[A, B] =
## creates a new hash table that contains the given `pairs`.
result = initTable[A, B](nextPowerOfTwo(pairs.len+10))
for key, val in items(pairs): result[key] = val
template dollarImpl(): stmt =
if t.len == 0:
result = "{:}"
else:
result = "{"
for key, val in pairs(t):
if result.len > 1: result.add(", ")
result.add($key)
result.add(": ")
result.add($val)
result.add("}")
proc `$`*[A, B](t: TTable[A, B]): string =
## The `$` operator for hash tables.
dollarImpl()
# ------------------------------ count tables -------------------------------
type
TCountTable* {.final, myShallow.}[
A] = object ## table that counts the number of each key
data: seq[tuple[key: A, val: int]]
counter: int
proc len*[A](t: TCountTable[A]): int =
## returns the number of keys in `t`.
result = t.counter
iterator pairs*[A](t: TCountTable[A]): tuple[key: A, val: int] =
## iterates over any (key, value) pair in the table `t`.
for h in 0..high(t.data):
if t.data[h].val != 0: yield (t.data[h].key, t.data[h].val)
iterator keys*[A](t: TCountTable[A]): A =
## iterates over any key in the table `t`.
for h in 0..high(t.data):
if t.data[h].val != 0: yield t.data[h].key
iterator values*[A](t: TCountTable[A]): int =
## iterates over any value in the table `t`.
for h in 0..high(t.data):
if t.data[h].val != 0: yield t.data[h].val
proc RawGet[A](t: TCountTable[A], key: A): int =
var h: THash = hash(key) and high(t.data) # start with real hash value
while t.data[h].val != 0:
if t.data[h].key == key: return h
h = nextTry(h, high(t.data))
result = -1
proc `[]`*[A](t: TCountTable[A], key: A): int =
## retrieves the value at ``t[key]``. If `key` is not in `t`,
## 0 is returned. One can check with ``hasKey`` whether the key
## exists.
var index = RawGet(t, key)
if index >= 0: result = t.data[index].val
proc hasKey*[A](t: TCountTable[A], key: A): bool =
## returns true iff `key` is in the table `t`.
result = rawGet(t, key) >= 0
proc RawInsert[A](t: TCountTable[A], data: var seq[tuple[key: A, val: int]],
key: A, val: int) =
var h: THash = hash(key) and high(data)
while data[h].val != 0: h = nextTry(h, high(data))
data[h].key = key
data[h].val = val
proc Enlarge[A](t: var TCountTable[A]) =
var n: seq[tuple[key: A, val: int]]
newSeq(n, len(t.data) * growthFactor)
for i in countup(0, high(t.data)):
if t.data[i].val != 0: RawInsert(t, n, t.data[i].key, t.data[i].val)
swap(t.data, n)
proc `[]=`*[A](t: var TCountTable[A], key: A, val: int) =
## puts a (key, value)-pair into `t`. `val` has to be positive.
assert val > 0
PutImpl()
proc initCountTable*[A](initialSize=64): TCountTable[A] =
## creates a new count table that is empty. `initialSize` needs to be
## a power of two.
assert isPowerOfTwo(initialSize)
result.counter = 0
newSeq(result.data, initialSize)
proc toCountTable*[A](keys: openArray[A]): TCountTable[A] =
## creates a new count table with every key in `keys` having a count of 1.
result = initCountTable[A](nextPowerOfTwo(keys.len+10))
for key in items(keys): result[key] = 1
proc `$`*[A](t: TCountTable[A]): string =
## The `$` operator for count tables.
dollarImpl()
proc inc*[A](t: var TCountTable[A], key: A, val = 1) =
## increments `t[key]` by `val`.
var index = RawGet(t, key)
if index >= 0:
inc(t.data[index].val, val)
else:
if mustRehash(len(t.data), t.counter): Enlarge(t)
RawInsert(t, t.data, key, val)
inc(t.counter)
proc Smallest*[A](t: TCountTable[A]): tuple[key: A, val: int] =
## returns the largest (key,val)-pair. Efficiency: O(n)
assert t.len > 0
var minIdx = 0
for h in 1..high(t.data):
if t.data[h].val > 0 and t.data[minIdx].val > t.data[h].val: minIdx = h
result.key = t.data[minIdx].key
result.val = t.data[minIdx].val
proc Largest*[A](t: TCountTable[A]): tuple[key: A, val: int] =
## returns the (key,val)-pair with the largest `val`. Efficiency: O(n)
assert t.len > 0
var maxIdx = 0
for h in 1..high(t.data):
if t.data[maxIdx].val < t.data[h].val: maxIdx = h
result.key = t.data[maxIdx].key
result.val = t.data[maxIdx].val
proc sort*[A](t: var TCountTable[A]) =
## sorts the count table so that the entry with the highest counter comes
## first. This is destructive! You must not modify `t` afterwards!
## You can use the iterators `pairs`, `keys`, and `values` to iterate over
## `t` in the sorted order.
# we use shellsort here; fast enough and simple
var h = 1
while true:
h = 3 * h + 1
if h >= high(t.data): break
while true:
h = h div 3
for i in countup(h, high(t.data)):
var j = i
while t.data[j-h].val <= t.data[j].val:
var xyz = t.data[j]
t.data[j] = t.data[j-h]
t.data[j-h] = xyz
j = j-h
if j < h: break
if h == 1: break
const
data = {
"34": 123456, "12": 789,
"90": 343, "0": 34404,
"1": 344004, "2": 344774,
"3": 342244, "4": 3412344,
"5": 341232144, "6": 34214544,
"7": 3434544, "8": 344544,
"9": 34435644, "---00": 346677844,
"10": 34484, "11": 34474, "19": 34464,
"20": 34454, "30": 34141244, "40": 344114,
"50": 344490, "60": 344491, "70": 344492,
"80": 344497}
proc countTableTest1 =
var s = initTable[string, int](64)
for key, val in items(data): s[key] = val
var w: tuple[key: string, val: int] #type(otherCountTable.data[0])
var t = initCountTable[string]()
for k, v in items(data): t.inc(k)
for k in t.keys: assert t[k] == 1
t.inc("90", 3)
t.inc("12", 2)
t.inc("34", 1)
assert t.largest()[0] == "90"
t.sort()
var i = 0
for k, v in t.pairs:
case i
of 0: assert k == "90" and v == 4
of 1: assert k == "12" and v == 3
of 2: assert k == "34" and v == 2
else: break
inc i
countTableTest1()
echo true