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keyed_queue: avoid copies, lookups (#220) 

This change avoids many superfluous data copies and lookups by
exploiting `withValue` thus performing only one lookup with the same key
(instead of hasKey + actual lookup).

We also avoid several copies of the value which often is copied even
though only the next/prev pointers from the item are needed, for examle
during shifting and lru-appending.
This commit is contained in:
Jacek Sieka 2024-06-11 08:43:41 +02:00 committed by GitHub
parent a0a53c9116
commit 28743363ff
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1 changed files with 296 additions and 316 deletions
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stew/keyed_queue.nim
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@ -22,17 +22,14 @@
## semantics, this means that `=` performs a deep copy of the allocated queue
## which is refered to the deep copy semantics of the underlying table driver.
import
std/[math, tables],
./results
import std/tables, results
export
results
export results
{.push raises: [].}
type
KeyedQueueItem*[K,V] = object ##\
KeyedQueueItem*[K, V] = object
## Data value container as stored in the queue.
## There is a special requirements for `KeyedQueueItem` terminal nodes:
## *prv == nxt* so that there is no dangling link. On the flip side,
@ -41,33 +38,26 @@ type
data*: V ## Some data value, can freely be modified.
kPrv*, kNxt*: K ## Queue links, read-only.
KeyedQueuePair*[K,V] = object ##\
## Key-value pair, typically used as return code.
KeyedQueuePair*[K, V] = object ## Key-value pair, typically used as return code.
key: K ## Sorter key (read-only for consistency with `SLstResult[K,V]`)
data*: V ## Some data value, to be modified freely
KeyedQueueTab*[K,V] = ##\
KeyedQueueTab*[K, V] = Table[K, KeyedQueueItem[K, V]]
## Internal table type exposed for debugging.
Table[K,KeyedQueueItem[K,V]]
KeyedQueue*[K,V] = object ##\
## Data queue descriptor
KeyedQueue*[K, V] = object ## Data queue descriptor
tab*: KeyedQueueTab[K, V] ## Data table
kFirst*, kLast*: K ## Doubly linked item list queue
BlindValue = ##\
## Type name is syntactic sugar, used for key-only queues
distinct byte
BlindValue = distinct tuple[] ## Type name is syntactic sugar, used for key-only queues
KeyedQueueNV*[K] = ##\
## Key-only queue, no values
KeyedQueue[K,BlindValue]
KeyedQueueNV*[K] = KeyedQueue[K, BlindValue] ## Key-only queue, no values
# ------------------------------------------------------------------------------
# Private helpers
# ------------------------------------------------------------------------------
template noKeyError(info: static[string]; code: untyped) =
template noKeyError(info: static[string], code: untyped) =
try:
code
except KeyError as e:
@ -81,180 +71,193 @@ proc shiftImpl[K,V](rq: var KeyedQueue[K,V]) =
## Expects: rq.tab.len != 0
assert rq.tab.len != 0 # debugging only
noKeyError("shiftImpl"):
# Unqueue first item
let item = rq.tab[rq.kFirst] # yes, crashes if `rq.tab.len == 0`
rq.tab.del(rq.kFirst)
if rq.tab.len == 0:
let first = rq.kFirst
rq.tab.withValue(first, item):
if rq.tab.len == 1: # item only
rq.kFirst.reset
rq.kLast.reset
else:
rq.kFirst = item.kNxt
if rq.tab.len == 1:
rq.tab[rq.kFirst].kNxt = rq.kFirst # node points to itself
rq.tab[rq.kFirst].kPrv = rq.tab[rq.kFirst].kNxt # term nd has: nxt == prv
rq.tab.withValue(item[].kNxt, next):
if rq.tab.len == 2: # item and one more
next[].kNxt = item[].kNxt # node points to itself
next[].kPrv = next[].kNxt # term nd has: nxt == prv
rq.kFirst = item[].kNxt
do:
raiseAssert "rq.kFirst missing"
rq.tab.del(first)
proc popImpl[K, V](rq: var KeyedQueue[K, V]) =
## Expects: rq.tab.len != 0
# Pop last item
noKeyError("popImpl"):
let item = rq.tab[rq.kLast] # yes, crashes if `rq.tab.len == 0`
rq.tab.del(rq.kLast)
if rq.tab.len == 0:
let last = rq.kLast
rq.tab.withValue(last, item):
if rq.tab.len == 1: # item only
rq.kFirst.reset
rq.kLast.reset
else:
rq.kLast = item.kPrv
if rq.tab.len == 1:
rq.tab[rq.kLast].kPrv = rq.kLast # single node points to itself
rq.tab[rq.kLast].kNxt = rq.tab[rq.kLast].kPrv # term node has: nxt == prv
rq.tab.withValue(item[].kPrv, prev):
if rq.tab.len == 2: # item and one more
prev[].kPrv = item[].kPrv # single node points to itself
prev[].kNxt = prev[].kPrv # term node has: nxt == prv
rq.kLast = item[].kPrv
do:
raiseAssert "rq.kLast missing"
rq.tab.del(last)
proc deleteImpl[K,V](rq: var KeyedQueue[K,V]; key: K) =
proc deleteImpl[K, V](rq: var KeyedQueue[K, V], key: K) =
## Expects: rq.tab.hesKey(key)
if rq.kFirst == key:
rq.shiftImpl
elif rq.kLast == key:
rq.popImpl
else:
noKeyError("deleteImpl"):
let item = rq.tab[key] # yes, crashes if `not rq.tab.hasKey(key)`
rq.tab.withValue(key, item):
# now: 2 < rq.tab.len (otherwise rq.kFirst == key or rq.kLast == key)
rq.tab.withValue(rq.kFirst, first):
if first[].kNxt == key:
# item was the second one
first[].kPrv = item[].kNxt
rq.tab.withValue(rq.kLast, last):
if last.kPrv == key:
# item was one before last
last.kNxt = item[].kPrv
rq.tab.withValue(item[].kPrv, other):
other[].kNxt = item[].kNxt
rq.tab.withValue(item[].kNxt, other):
other[].kPrv = item[].kPrv
do:
raiseAssert "item missing"
rq.tab.del(key)
# now: 2 < rq.tab.len (otherwise rq.kFirst == key or rq.kLast == key)
if rq.tab[rq.kFirst].kNxt == key:
# item was the second one
rq.tab[rq.kFirst].kPrv = item.kNxt
if rq.tab[rq.kLast].kPrv == key:
# item was one before last
rq.tab[rq.kLast].kNxt = item.kPrv
rq.tab[item.kPrv].kNxt = item.kNxt
rq.tab[item.kNxt].kPrv = item.kPrv
proc appendImpl[K,V](rq: var KeyedQueue[K,V]; key: K; val: V) =
proc appendImpl[K, V](rq: var KeyedQueue[K, V], key: K, val: V) =
## Expects: not rq.tab.hasKey(key)
# Append queue item
var item = KeyedQueueItem[K, V](data: val)
noKeyError("appendImpl"):
if rq.tab.len == 0:
rq.kFirst = key
item.kPrv = key
else:
if rq.kFirst == rq.kLast:
rq.tab[rq.kFirst].kPrv = key # first terminal node
rq.tab[rq.kLast].kNxt = key
rq.tab.withValue(rq.kFirst, first):
first[].kPrv = key
first[].kNxt = key
else:
rq.tab.withValue(rq.kLast, last):
last[].kNxt = key
item.kPrv = rq.kLast
rq.kLast = key
item.kNxt = item.kPrv # terminal node
rq.tab[key] = item # yes, makes `verify()` fail if `rq.tab.hasKey(key)`
rq.tab[key] = move(item)
proc prependImpl[K,V](rq: var KeyedQueue[K,V]; key: K; val: V) =
proc prependImpl[K, V](rq: var KeyedQueue[K, V], key: K, val: V) =
## Expects: not rq.tab.hasKey(key)
# Prepend queue item
var item = KeyedQueueItem[K, V](data: val)
noKeyError("prependImpl"):
if rq.tab.len == 0:
rq.kLast = key
item.kNxt = key
else:
if rq.kFirst == rq.kLast:
rq.tab[rq.kLast].kNxt = key # first terminal node
rq.tab[rq.kFirst].kPrv = key
rq.tab.withValue(rq.kLast, last):
last[].kNxt = key
last[].kPrv = key
else:
rq.tab.withValue(rq.kFirst, first):
first[].kPrv = key
item.kNxt = rq.kFirst
rq.kFirst = key
item.kPrv = item.kNxt # terminal node has: nxt == prv
rq.tab[key] = item # yes, makes `verify()` fail if `rq.tab.hasKey(key)`
rq.tab[key] = move(item)
# -----------
proc shiftKeyImpl[K,V](rq: var KeyedQueue[K,V]): Result[K,void] =
noKeyError("shiftKeyImpl"):
proc shiftKeyImpl[K, V](rq: var KeyedQueue[K, V]): Opt[K] =
if 0 < rq.tab.len:
let key = rq.kFirst
rq.shiftImpl
return ok(key)
err()
Opt.some(key)
else:
Opt.none(K)
proc popKeyImpl[K,V](rq: var KeyedQueue[K,V]): Result[K,void] =
noKeyError("popKeyImpl"):
proc popKeyImpl[K, V](rq: var KeyedQueue[K, V]): Opt[K] =
if 0 < rq.tab.len:
let key = rq.kLast
rq.popImpl
return ok(key)
err()
Opt.some(key)
else:
Opt.none(K)
# -----------
proc firstKeyImpl[K,V](rq: var KeyedQueue[K,V]): Result[K,void] =
proc firstKeyImpl[K, V](rq: var KeyedQueue[K, V]): Opt[K] =
if rq.tab.len == 0:
return err()
ok(rq.kFirst)
Opt.none(K)
else:
Opt.some(rq.kFirst)
proc secondKeyImpl[K,V](rq: var KeyedQueue[K,V]): Result[K,void] =
proc secondKeyImpl[K, V](rq: var KeyedQueue[K, V]): Opt[K] =
if rq.tab.len < 2:
return err()
return Opt.none(K)
noKeyError("secondKeyImpl"):
return ok(rq.tab[rq.kFirst].kNxt)
return Opt.some(rq.tab[rq.kFirst].kNxt)
proc beforeLastKeyImpl[K,V](rq: var KeyedQueue[K,V]): Result[K,void] =
proc beforeLastKeyImpl[K, V](rq: var KeyedQueue[K, V]): Opt[K] =
if rq.tab.len < 2:
return err()
return Opt.none(K)
noKeyError("lastKeyImpl"):
return ok(rq.tab[rq.kLast].kPrv)
return Opt.some(rq.tab[rq.kLast].kPrv)
proc lastKeyImpl[K,V](rq: var KeyedQueue[K,V]): Result[K,void] =
proc lastKeyImpl[K, V](rq: var KeyedQueue[K, V]): Opt[K] =
if rq.tab.len == 0:
return err()
ok(rq.kLast)
Opt.none(K)
else:
Opt.some(rq.kLast)
proc nextKeyImpl[K,V](rq: var KeyedQueue[K,V]; key: K): Result[K,void] =
proc nextKeyImpl[K, V](rq: var KeyedQueue[K, V], key: K): Opt[K] =
if not rq.tab.hasKey(key) or rq.kLast == key:
return err()
return Opt.none(K)
noKeyError("nextKeyImpl"):
return ok(rq.tab[key].kNxt)
return Opt.some(rq.tab[key].kNxt)
proc prevKeyImpl[K,V](rq: var KeyedQueue[K,V]; key: K): Result[K,void] =
proc prevKeyImpl[K, V](rq: var KeyedQueue[K, V], key: K): Opt[K] =
if not rq.tab.hasKey(key) or rq.kFirst == key:
return err()
return Opt.none(K)
noKeyError("prevKeyImpl"):
return ok(rq.tab[key].kPrv)
return Opt.some(rq.tab[key].kPrv)
# ------------------------------------------------------------------------------
# Public functions, constructor
# ------------------------------------------------------------------------------
proc init*[K,V](rq: var KeyedQueue[K,V]; initSize = 10) =
proc init*[K, V](rq: var KeyedQueue[K, V], initSize = defaultInitialSize) =
## Optional initaliser for the queue setting the inital size of the
## underlying table object.
rq.tab = initTable[K,KeyedQueueItem[K,V]](initSize.nextPowerOfTwo)
rq.tab = initTable[K, KeyedQueueItem[K, V]](initSize)
proc init*[K,V](T: type KeyedQueue[K,V]; initSize = 10): T =
proc init*[K, V](T: type KeyedQueue[K, V], initSize = defaultInitialSize): T =
## Initaliser variant.
result.init(initSize)
proc init*[K](rq: var KeyedQueueNV[K]; initSize = 10) =
proc init*[K](rq: var KeyedQueueNV[K], initSize = defaultInitialSize) =
## Key-only queue, no explicit values
rq.tab = initTable[K,KeyedQueueItem[K,BlindValue]](initSize.nextPowerOfTwo)
rq.tab = initTable[K, KeyedQueueItem[K, BlindValue]](initSize)
proc init*[K](T: type KeyedQueueNV[K]; initSize = 10): T =
proc init*[K](T: type KeyedQueueNV[K], initSize = defaultInitialSize): T =
## Initaliser variant.
result.init(initSize)
@ -262,61 +265,62 @@ proc init*[K](T: type KeyedQueueNV[K]; initSize = 10): T =
# Public functions, list operations
# ------------------------------------------------------------------------------
proc append*[K,V](rq: var KeyedQueue[K,V]; key: K; val: V): bool =
proc append*[K, V](rq: var KeyedQueue[K, V], key: K, val: V): bool =
## Append new `key`. The function will succeed returning `true` unless the
## `key` argument exists in the queue, already.
##
## All the items on the queue different from the one just added are
## called *previous* or *left hand* items while the item just added
## is the *right-most* item.
if not rq.tab.hasKey(key):
rq.tab.withValue(key, item):
return false
do:
rq.appendImpl(key, val)
return true
template push*[K,V](rq: var KeyedQueue[K,V]; key: K; val: V): bool =
template push*[K, V](rq: var KeyedQueue[K, V], key: K, val: V): bool =
## Same as `append()`
rq.append(key, val)
proc replace*[K,V](rq: var KeyedQueue[K,V]; key: K; val: V): bool =
proc replace*[K, V](rq: var KeyedQueue[K, V], key: K, val: V): bool =
## Replace value for entry associated with the key argument `key`. Returns
## `true` on success, and `false` otherwise.
if rq.tab.hasKey(key):
noKeyError("replace"):
rq.tab[key].data = val
rq.tab.withValue(key, item):
item[].data = val
return true
do:
return false
proc `[]=`*[K,V](rq: var KeyedQueue[K,V]; key: K; val: V) =
proc `[]=`*[K, V](rq: var KeyedQueue[K, V], key: K, val: V) =
## This function provides a combined append/replace action with table
## semantics:
## * If the argument `key` is not in the queue yet, append the `(key,val)`
## pair as in `rq.append(key,val)`
## * Otherwise replace the value entry of the queue item by the argument
## `val` as in `rq.replace(key,val)`
if rq.tab.hasKey(key):
noKeyError("[]="):
rq.tab[key].data = val
else:
rq.tab.withValue(key, item):
item[].data = val
do:
rq.appendImpl(key, val)
proc prepend*[K,V](rq: var KeyedQueue[K,V]; key: K; val: V): bool =
proc prepend*[K, V](rq: var KeyedQueue[K, V], key: K, val: V): bool =
## Prepend new `key`. The function will succeed returning `true` unless the
## `key` argument exists in the queue, already.
##
## All the items on the queue different from the item just added are
## called *following* or *right hand* items while the item just added
## is the *left-most* item.
if not rq.tab.hasKey(key):
rq.tab.withValue(key, item):
return false
do:
rq.prependImpl(key, val)
return true
template unshift*[K,V](rq: var KeyedQueue[K,V]; key: K; val: V): bool =
template unshift*[K, V](rq: var KeyedQueue[K, V], key: K, val: V): bool =
## Same as `prepend()`
rq.prepend(key, val)
proc shift*[K,V](rq: var KeyedQueue[K,V]): Result[KeyedQueuePair[K,V],void] =
proc shift*[K, V](rq: var KeyedQueue[K, V]): Opt[KeyedQueuePair[K, V]] =
## Deletes the *first* queue item and returns the key-value item pair just
## deleted. For a non-empty queue this function is the same as
## `rq.firstKey.value.delele`.
@ -325,32 +329,26 @@ proc shift*[K,V](rq: var KeyedQueue[K,V]): Result[KeyedQueuePair[K,V],void] =
## item returned and deleted is the *left-most* item.
type T = KeyedQueuePair[K, V]
if 0 < rq.tab.len:
noKeyError("shift"):
let kvp = KeyedQueuePair[K,V](
key: rq.kFirst,
data: rq.tab[rq.kFirst].data)
rq.tab.withValue(rq.kFirst, item):
let res = Opt.some KeyedQueuePair[K, V](key: rq.kFirst, data: move(item[].data))
rq.shiftImpl
when kvp is T:
return ok(kvp)
else:
return ok(T(kvp))
err()
return res
Opt.none(KeyedQueuePair[K, V])
proc shiftKey*[K,V](rq: var KeyedQueue[K,V]): Result[K,void] =
proc shiftKey*[K, V](rq: var KeyedQueue[K, V]): Opt[K] =
## Similar to `shift()` but with different return value.
rq.shiftKeyImpl
proc shiftValue*[K,V](rq: var KeyedQueue[K,V]): Result[V,void] =
proc shiftValue*[K, V](rq: var KeyedQueue[K, V]): Opt[V] =
## Similar to `shift()` but with different return value.
if 0 < rq.tab.len:
noKeyError("shiftValue"):
let val = rq.tab[rq.kFirst].data
rq.tab.withValue(rq.kFirst, item):
let res = Opt.some(move(item[].data))
rq.shiftImpl
return ok(val)
err()
return res
Opt.none(V)
proc pop*[K,V](rq: var KeyedQueue[K,V]): Result[KeyedQueuePair[K,V],void] =
proc pop*[K, V](rq: var KeyedQueue[K, V]): Opt[KeyedQueuePair[K, V]] =
## Deletes the *last* queue item and returns the key-value item pair just
## deleted. For a non-empty queue this function is the same as
## `rq.lastKey.value.delele`.
@ -359,104 +357,84 @@ proc pop*[K,V](rq: var KeyedQueue[K,V]): Result[KeyedQueuePair[K,V],void] =
## item returned and deleted is the *right-most* item.
type T = KeyedQueuePair[K, V]
if 0 < rq.tab.len:
noKeyError("pop"):
let kvp = KeyedQueuePair[K,V](
key: rq.kLast,
data: rq.tab[rq.kLast].data)
rq.tab.withValue(rq.kLast, item):
let res = Opt.some T(key: rq.kLast, data: move(item[].data))
rq.popImpl
when kvp is T:
return ok(kvp)
else:
return ok(T(kvp))
err()
return res
Opt.none(T)
proc popKey*[K,V](rq: var KeyedQueue[K,V]): Result[K,void] =
proc popKey*[K, V](rq: var KeyedQueue[K, V]): Opt[K] =
## Similar to `pop()` but with different return value.
rq.popKeyImpl
proc popValue*[K,V](rq: var KeyedQueue[K,V]): Result[V,void] =
proc popValue*[K, V](rq: var KeyedQueue[K, V]): Opt[V] =
## Similar to `pop()` but with different return value.
if 0 < rq.tab.len:
noKeyError("popValue"):
let val = rq.tab[rq.kLast].data
rq.tab.withValue(rq.kLast, item):
let res = Opt.some move(item[].data)
rq.popImpl
return ok(val)
err()
return res
Opt.none(V)
proc delete*[K,V](rq: var KeyedQueue[K,V]; key: K):
Result[KeyedQueuePair[K,V], void] =
proc delete*[K, V](rq: var KeyedQueue[K, V], key: K): Opt[KeyedQueuePair[K, V]] =
## Delete the item with key `key` from the queue and returns the key-value
## item pair just deleted (if any).
if rq.tab.hasKey(key):
noKeyError("delete"):
let kvp = KeyedQueuePair[K,V](
key: key,
data: rq.tab[key].data)
type T = KeyedQueuePair[K, V]
rq.tab.withValue(key, item):
let res = Opt.some T(key: key, data: move(item[].data))
rq.deleteImpl(key)
return ok(kvp)
err()
return res
proc del*[K,V](rq: var KeyedQueue[K,V]; key: K) =
Opt.none(T)
proc del*[K, V](rq: var KeyedQueue[K, V], key: K) =
## Similar to `delete()` but without return code.
if rq.tab.hasKey(key):
rq.deleteImpl(key)
# --------
proc append*[K](rq: var KeyedQueueNV[K]; key: K): bool =
proc append*[K](rq: var KeyedQueueNV[K], key: K): bool =
## Key-only queue variant
rq.append(key,BlindValue(0))
rq.append(key, default(BlindValue))
template push*[K](rq: var KeyedQueueNV[K]; key: K): bool =
template push*[K](rq: var KeyedQueueNV[K], key: K): bool =
## Key-only queue variant
rq.append(key)
proc prepend*[K](rq: var KeyedQueueNV[K]; key: K): bool =
proc prepend*[K](rq: var KeyedQueueNV[K], key: K): bool =
## Key-only queue variant
rq.prepend(key,BlindValue(0))
rq.prepend(key, default(BlindValue))
template unshift*[K](rq: var KeyedQueueNV[K]; key: K): bool =
template unshift*[K](rq: var KeyedQueueNV[K], key: K): bool =
## Key-only queue variant
rq.prepend(key)
proc shift*[K](rq: var KeyedQueueNV[K]): Result[K,void] =
proc shift*[K](rq: var KeyedQueueNV[K]): Opt[K] =
## Key-only queue variant
rq.shiftKeyImpl
proc shiftKey*[K](rq: var KeyedQueueNV[K]): Result[K,void]
{.gcsafe, deprecated: "use shift() for key-only queue".} =
rq.shiftKeyImpl
proc pop*[K](rq: var KeyedQueueNV[K]): Result[K,void] =
proc pop*[K](rq: var KeyedQueueNV[K]): Opt[K] =
## Key-only variant of `pop()` (same as `popKey()`)
rq.popKeyImpl
proc popKey*[K](rq: var KeyedQueueNV[K]): Result[K,void]
{.gcsafe, deprecated: "use pop() for key-only queue".} =
rq.popKeyImpl
# ------------------------------------------------------------------------------
# Public functions, fetch
# ------------------------------------------------------------------------------
proc hasKey*[K,V](rq: var KeyedQueue[K,V]; key: K): bool =
proc hasKey*[K, V](rq: var KeyedQueue[K, V], key: K): bool =
## Check whether the argument `key` has been queued, already
rq.tab.hasKey(key)
proc eq*[K,V](rq: var KeyedQueue[K,V]; key: K): Result[V,void] =
proc eq*[K, V](rq: var KeyedQueue[K, V], key: K): Opt[V] =
## Retrieve the value data stored with the argument `key` from
## the queue if there is any.
if not rq.tab.hasKey(key):
return err()
return Opt.none(V)
noKeyError("eq"):
return ok(rq.tab[key].data)
return Opt.some(rq.tab[key].data)
proc `[]`*[K,V](rq: var KeyedQueue[K,V]; key: K): V
{.gcsafe,raises: [KeyError].} =
proc `[]`*[K, V](rq: var KeyedQueue[K, V], key: K): var V {.raises: [KeyError].} =
## This function provides a simplified version of the `eq()` function with
## table semantics. Note that this finction throws a `KeyError` exception
## unless the argument `key` exists in the queue.
@ -466,38 +444,39 @@ proc `[]`*[K,V](rq: var KeyedQueue[K,V]; key: K): V
# Public functions, LRU mode
# ------------------------------------------------------------------------------
proc lruFetch*[K,V](rq: var KeyedQueue[K,V]; key: K): Result[V,void] =
proc lruFetch*[K, V](rq: var KeyedQueue[K, V], key: K): Opt[V] =
## Fetch in *last-recently-used* mode: If the argument `key` exists in the
## queue, move the key-value item pair to the *right end* (see `append()`)
## of the queue and return the value associated with the key.
if not rq.tab.hasKey(key):
return err()
noKeyError("lruFetch"):
let item = rq.tab[key]
rq.tab.withValue(key, item):
if rq.kLast != key:
# Now, `key` is in the table and does not refer to the last `item`,
# so the table has at least two entries.
# unlink item
if rq.kFirst == key:
rq.kFirst = item.kNxt
rq.tab[rq.kFirst].kPrv = rq.tab[rq.kFirst].kNxt # term node: nxt == prv
rq.kFirst = item[].kNxt
rq.tab.withValue(rq.kFirst, first):
first[].kPrv = first[].kNxt # term node: nxt == prv
else: # Now, there are at least three entries
if rq.tab[rq.kFirst].kNxt == key:
rq.tab[rq.kFirst].kPrv = item.kNxt # item was the 2nd one
rq.tab[item.kPrv].kNxt = item.kNxt
rq.tab[item.kNxt].kPrv = item.kPrv
rq.tab.withValue(rq.kFirst, first):
if first[].kNxt == key:
first[].kPrv = item[].kNxt # item was the 2nd one
rq.tab.withValue(item[].kPrv, prev):
prev[].kNxt = item[].kNxt
rq.tab.withValue(item[].kNxt, next):
next[].kPrv = item[].kPrv
# Re-append item, i.e. appendImpl() without adding item.
rq.tab[rq.kLast].kNxt = key
rq.tab[key].kPrv = rq.kLast
rq.kLast = key
rq.tab[key].kNxt = rq.tab[key].kPrv # term node: nxt == prv
return ok(item.data)
rq.tab.withValue(rq.kLast, last):
last[].kNxt = key
proc lruUpdate*[K,V](rq: var KeyedQueue[K,V]; key: K; val: V): bool =
item[].kPrv = rq.kLast
rq.kLast = key
item[].kNxt = item[].kPrv # term node: nxt == prv
return Opt.some(item[].data)
proc lruUpdate*[K, V](rq: var KeyedQueue[K, V], key: K, val: V): bool =
## Similar to `lruFetch()` with the difference that the item value is
## updated (i.e. set to `val`) if it is found on the queue. In that case,
## `true` is returned.
@ -505,11 +484,11 @@ proc lruUpdate*[K,V](rq: var KeyedQueue[K,V]; key: K; val: V): bool =
## Otherwise `false` is returned.
##
rq.tab.withValue(key, w):
w.data = val
w[].data = val
discard rq.lruFetch key
return true
proc lruAppend*[K,V](rq: var KeyedQueue[K,V]; key: K; val: V; maxItems: int): V =
proc lruAppend*[K, V](rq: var KeyedQueue[K, V], key: K, val: V, maxItems: int): V =
## Append in *last-recently-used* mode: If the queue has at least `maxItems`
## item entries, do `shift()` out the *left-most* one. Then `append()` the
## key-value argument pair `(key,val)` to the *right end*. Together with
@ -527,12 +506,12 @@ proc lruAppend*[K,V](rq: var KeyedQueue[K,V]; key: K; val: V; maxItems: int): V
## block:
## let rc = q.lruFetch(key)
## if rc.isOK:
## return ok(rc.value)
## return Opt.some(rc.value)
## block:
## let rc = expensiveCalculation(key)
## if rc.isOK:
## return ok(q.lruAppend(key, rc.value, queueMax))
## err()
## return Opt.some(q.lruAppend(key, rc.value, queueMax))
## Opt.none(K)
##
## Caveat:
## This fuction must always be used in combination with `lruFetch()` or
@ -542,7 +521,6 @@ proc lruAppend*[K,V](rq: var KeyedQueue[K,V]; key: K; val: V; maxItems: int): V
# Make sure that there is no such key. Otherwise the optimised `appendImpl()`
# function might garble the list of links.
doAssert not rq.tab.hasKey key
# Limit number of cached items
try:
if maxItems <= rq.tab.len:
@ -557,35 +535,35 @@ proc lruAppend*[K,V](rq: var KeyedQueue[K,V]; key: K; val: V; maxItems: int): V
# Public traversal functions, fetch keys
# ------------------------------------------------------------------------------
proc firstKey*[K,V](rq: var KeyedQueue[K,V]): Result[K,void] =
proc firstKey*[K, V](rq: var KeyedQueue[K, V]): Opt[K] =
## Retrieve first key from the queue unless it is empty.
##
## Using the notation introduced with `rq.append` and `rq.prepend`, the
## key returned is the *left-most* one.
rq.firstKeyImpl
proc secondKey*[K,V](rq: var KeyedQueue[K,V]): Result[K,void] =
proc secondKey*[K, V](rq: var KeyedQueue[K, V]): Opt[K] =
## Retrieve the key next after the first key from queue unless it is empty.
##
## Using the notation introduced with `rq.append` and `rq.prepend`, the
## key returned is the one ti the right of the *left-most* one.
rq.secondKeyImpl
proc beforeLastKey*[K,V](rq: var KeyedQueue[K,V]): Result[K,void] =
proc beforeLastKey*[K, V](rq: var KeyedQueue[K, V]): Opt[K] =
## Retrieve the key just before the last one from queue unless it is empty.
##
## Using the notation introduced with `rq.append` and `rq.prepend`, the
## key returned is the one to the left of the *right-most* one.
rq.beforeLastKeyImpl
proc lastKey*[K,V](rq: var KeyedQueue[K,V]): Result[K,void] =
proc lastKey*[K, V](rq: var KeyedQueue[K, V]): Opt[K] =
## Retrieve last key from queue unless it is empty.
##
## Using the notation introduced with `rq.append` and `rq.prepend`, the
## key returned is the *right-most* one.
rq.lastKeyImpl
proc nextKey*[K,V](rq: var KeyedQueue[K,V]; key: K): Result[K,void] =
proc nextKey*[K, V](rq: var KeyedQueue[K, V], key: K): Opt[K] =
## Retrieve the key following the argument `key` from queue if
## there is any.
##
@ -593,7 +571,7 @@ proc nextKey*[K,V](rq: var KeyedQueue[K,V]; key: K): Result[K,void] =
## key returned is the next one to the *right*.
rq.nextKeyImpl(key)
proc prevKey*[K,V](rq: var KeyedQueue[K,V]; key: K): Result[K,void] =
proc prevKey*[K, V](rq: var KeyedQueue[K, V], key: K): Opt[K] =
## Retrieve the key preceeding the argument `key` from queue if
## there is any.
##
@ -603,108 +581,111 @@ proc prevKey*[K,V](rq: var KeyedQueue[K,V]; key: K): Result[K,void] =
# ----------
proc firstKey*[K](rq: var KeyedQueueNV[K]): Result[K,void]
{.gcsafe, deprecated: "use first() for key-only queue".} =
proc firstKey*[K](
rq: var KeyedQueueNV[K]
): Opt[K] {.gcsafe, deprecated: "use first() for key-only queue".} =
rq.firstKeyImpl
proc secondKey*[K](rq: var KeyedQueueNV[K]): Result[K,void]
{.gcsafe, deprecated: "use second() for key-only queue".} =
proc secondKey*[K](
rq: var KeyedQueueNV[K]
): Opt[K] {.gcsafe, deprecated: "use second() for key-only queue".} =
rq.secondKeyImpl
proc beforeLastKey*[K](rq: var KeyedQueueNV[K]): Result[K,void]
{.gcsafe, deprecated: "use beforeLast() for key-only queue".} =
proc beforeLastKey*[K](
rq: var KeyedQueueNV[K]
): Opt[K] {.gcsafe, deprecated: "use beforeLast() for key-only queue".} =
rq.beforeLastKeyImpl
proc lastKey*[K](rq: var KeyedQueueNV[K]): Result[K,void]
{.gcsafe, deprecated: "use last() for key-only queue".} =
proc lastKey*[K](
rq: var KeyedQueueNV[K]
): Opt[K] {.gcsafe, deprecated: "use last() for key-only queue".} =
rq.lastKeyImpl
proc nextKey*[K](rq: var KeyedQueueNV[K]; key: K): Result[K,void]
{.gcsafe, deprecated: "use next() for key-only queue".} =
proc nextKey*[K](
rq: var KeyedQueueNV[K], key: K
): Opt[K] {.gcsafe, deprecated: "use next() for key-only queue".} =
rq.nextKeyImpl(key)
proc prevKey*[K](rq: var KeyedQueueNV[K]; key: K): Result[K,void]
{.gcsafe, deprecated: "use prev() for key-only queue".} =
proc prevKey*[K](
rq: var KeyedQueueNV[K], key: K
): Opt[K] {.gcsafe, deprecated: "use prev() for key-only queue".} =
rq.nextKeyImpl(key)
# ------------------------------------------------------------------------------
# Public traversal functions, fetch key/value pairs
# ------------------------------------------------------------------------------
proc first*[K,V](rq: var KeyedQueue[K,V]): Result[KeyedQueuePair[K,V],void] =
proc first*[K, V](rq: var KeyedQueue[K, V]): Opt[KeyedQueuePair[K, V]] =
## Similar to `firstKey()` but with key-value item pair return value.
if rq.tab.len == 0:
return err()
return Opt.none(KeyedQueuePair[K, V])
noKeyError("first"):
let key = rq.kFirst
return ok(KeyedQueuePair[K,V](key: key, data: rq.tab[key].data))
return Opt.some(KeyedQueuePair[K, V](key: key, data: rq.tab[key].data))
proc second*[K,V](rq: var KeyedQueue[K,V]): Result[KeyedQueuePair[K,V],void] =
proc second*[K, V](rq: var KeyedQueue[K, V]): Opt[KeyedQueuePair[K, V]] =
## Similar to `secondKey()` but with key-value item pair return value.
if rq.tab.len < 2:
return err()
return Opt.none(KeyedQueuePair[K, V])
noKeyError("second"):
let key = rq.tab[rq.kFirst].kNxt
return ok(KeyedQueuePair[K,V](key: key, data: rq.tab[key].data))
return Opt.some(KeyedQueuePair[K, V](key: key, data: rq.tab[key].data))
proc beforeLast*[K,V](rq: var KeyedQueue[K,V]):
Result[KeyedQueuePair[K,V],void] =
proc beforeLast*[K, V](rq: var KeyedQueue[K, V]): Opt[KeyedQueuePair[K, V]] =
## Similar to `beforeLastKey()` but with key-value item pair return value.
if rq.tab.len < 2:
return err()
return Opt.none(KeyedQueuePair[K, V])
noKeyError("beforeLast"):
let key = rq.tab[rq.kLast].kPrv
return ok(KeyedQueuePair[K,V](key: key, data: rq.tab[key].data))
return Opt.some(KeyedQueuePair[K, V](key: key, data: rq.tab[key].data))
proc last*[K,V](rq: var KeyedQueue[K,V]): Result[KeyedQueuePair[K,V],void] =
proc last*[K, V](rq: var KeyedQueue[K, V]): Opt[KeyedQueuePair[K, V]] =
## Similar to `lastKey()` but with key-value item pair return value.
if rq.tab.len == 0:
return err()
return Opt.none(KeyedQueuePair[K, V])
noKeyError("last"):
let key = rq.kLast
return ok(KeyedQueuePair[K,V](key: key, data: rq.tab[key].data))
return Opt.some(KeyedQueuePair[K, V](key: key, data: rq.tab[key].data))
proc next*[K,V](rq: var KeyedQueue[K,V]; key: K):
Result[KeyedQueuePair[K,V],void] =
proc next*[K, V](rq: var KeyedQueue[K, V], key: K): Opt[KeyedQueuePair[K, V]] =
## Similar to `nextKey()` but with key-value item pair return value.
if not rq.tab.hasKey(key) or rq.kLast == key:
return err()
return Opt.none(KeyedQueuePair[K, V])
noKeyError("next"):
let nKey = rq.tab[key].kNxt
return ok(KeyedQueuePair[K,V](key: nKey, data: rq.tab[nKey].data))
return Opt.some(KeyedQueuePair[K, V](key: nKey, data: rq.tab[nKey].data))
proc prev*[K,V](rq: var KeyedQueue[K,V]; key: K):
Result[KeyedQueuePair[K,V],void] =
proc prev*[K, V](rq: var KeyedQueue[K, V], key: K): Opt[KeyedQueuePair[K, V]] =
## Similar to `prevKey()` but with key-value item pair return value.
if not rq.tab.hasKey(key) or rq.kFirst == key:
return err()
return Opt.none(KeyedQueuePair[K, V])
noKeyError("prev"):
let pKey = rq.tab[key].kPrv
return ok(KeyedQueuePair[K,V](key: pKey, data: rq.tab[pKey].data))
return Opt.some(KeyedQueuePair[K, V](key: pKey, data: rq.tab[pKey].data))
# ------------
proc first*[K](rq: var KeyedQueueNV[K]): Result[K,void] =
proc first*[K](rq: var KeyedQueueNV[K]): Opt[K] =
## Key-only queue variant
rq.firstKeyImpl
proc second*[K](rq: var KeyedQueueNV[K]): Result[K,void] =
proc second*[K](rq: var KeyedQueueNV[K]): Opt[K] =
## Key-only queue variant
rq.secondKeyImpl
proc beforeLast*[K](rq: var KeyedQueueNV[K]): Result[K,void] =
proc beforeLast*[K](rq: var KeyedQueueNV[K]): Opt[K] =
## Key-only queue variant
rq.beforeLastKeyImpl
proc last*[K](rq: var KeyedQueueNV[K]): Result[K,void] =
proc last*[K](rq: var KeyedQueueNV[K]): Opt[K] =
## Key-only queue variant
rq.lastKeyImpl
proc next*[K](rq: var KeyedQueueNV[K]; key: K): Result[K,void] =
proc next*[K](rq: var KeyedQueueNV[K], key: K): Opt[K] =
## Key-only queue variant
rq.nextKeyImpl(key)
proc prev*[K](rq: var KeyedQueueNV[K]; key: K): Result[K,void] =
proc prev*[K](rq: var KeyedQueueNV[K], key: K): Opt[K] =
## Key-only queue variant
rq.nextKeyImpl(key)
@ -712,47 +693,47 @@ proc prev*[K](rq: var KeyedQueueNV[K]; key: K): Result[K,void] =
# Public traversal functions, data container items
# ------------------------------------------------------------------------------
proc firstValue*[K,V](rq: var KeyedQueue[K,V]): Result[V,void] =
proc firstValue*[K, V](rq: var KeyedQueue[K, V]): Opt[V] =
## Retrieve first value item from the queue unless it is empty.
##
## Using the notation introduced with `rq.append` and `rq.prepend`, the
## value item returned is the *left-most* one.
if rq.tab.len == 0:
return err()
return Opt.none(V)
noKeyError("firstValue"):
return ok(rq.tab[rq.kFirst].data)
return Opt.some(rq.tab[rq.kFirst].data)
proc secondValue*[K,V](rq: var KeyedQueue[K,V]): Result[V,void] =
proc secondValue*[K, V](rq: var KeyedQueue[K, V]): Opt[V] =
## Retrieve the value item next to the first one from the queue unless it
## is empty.
##
## Using the notation introduced with `rq.append` and `rq.prepend`, the
## value item returned is the one to the *right* of the *left-most* one.
if rq.tab.len < 2:
return err()
return Opt.none(K)
noKeyError("secondValue"):
return ok(rq.tab[rq.tab[rq.kFirst].kNxt].data)
return Opt.some(rq.tab[rq.tab[rq.kFirst].kNxt].data)
proc beforeLastValue*[K,V](rq: var KeyedQueue[K,V]): Result[V,void] =
proc beforeLastValue*[K, V](rq: var KeyedQueue[K, V]): Opt[V] =
## Retrieve the value item just before the last item from the queue
## unless it is empty.
##
## Using the notation introduced with `rq.append` and `rq.prepend`, the
## value item returned is the one to the *left* of the *right-most* one.
if rq.tab.len < 2:
return err()
return Opt.none(V)
noKeyError("beforeLastValue"):
return ok(rq.tab[rq.tab[rq.kLast].kPrv].data)
return Opt.some(rq.tab[rq.tab[rq.kLast].kPrv].data)
proc lastValue*[K,V](rq: var KeyedQueue[K,V]): Result[V,void] =
proc lastValue*[K, V](rq: var KeyedQueue[K, V]): Opt[V] =
## Retrieve the last value item from the queue if there is any.
##
## Using the notation introduced with `rq.append` and `rq.prepend`, the
## value item returned is the *right-most* one.
if rq.tab.len == 0:
return err()
return Opt.none(V)
noKeyError("lastValue"):
return ok(rq.tab[rq.kLast].data)
return Opt.some(rq.tab[rq.kLast].data)
# ------------------------------------------------------------------------------
# Public functions, miscellaneous
@ -786,10 +767,9 @@ proc clear*[K,V](rq: var KeyedQueue[K,V]) =
rq.kFirst.reset
rq.kLast.reset
proc toKeyedQueueResult*[K,V](key: K; data: V):
Result[KeyedQueuePair[K,V],void] =
## Helper, chreate `ok()` result
ok(KeyedQueuePair[K,V](key: key, data: data))
proc toKeyedQueueResult*[K, V](key: K, data: V): Opt[KeyedQueuePair[K, V]] =
## Helper, chreate `Opt.some()` result
Opt.some(KeyedQueuePair[K, V](key: key, data: data))
# ------------------------------------------------------------------------------
# Public iterators