std/critbits

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This module implements a crit bit tree which is an efficient container for a sorted set of strings, or for a sorted mapping of strings. Based on the excellent paper by Adam Langley. (A crit bit tree is a form of radix tree or patricia trie.)

Example:

import std/critbits
from std/sequtils import toSeq

var critbitAsSet: CritBitTree[void] = ["kitten", "puppy"].toCritBitTree
doAssert critbitAsSet.len == 2
critbitAsSet.incl("")
doAssert "" in critbitAsSet
critbitAsSet.excl("")
doAssert "" notin critbitAsSet
doAssert toSeq(critbitAsSet.items) == @["kitten", "puppy"]
let same = ["puppy", "kitten", "puppy"].toCritBitTree
doAssert toSeq(same.keys) == toSeq(critbitAsSet.keys)

var critbitAsDict: CritBitTree[int] = {"key1": 42}.toCritBitTree
doAssert critbitAsDict.len == 1
critbitAsDict["key2"] = 0
doAssert "key2" in critbitAsDict
doAssert critbitAsDict["key2"] == 0
critbitAsDict.excl("key1")
doAssert "key1" notin critbitAsDict
doAssert toSeq(critbitAsDict.pairs) == @[("key2", 0)]

Types

CritBitTree[T] = object
  root: Node[T]
  count: int
The crit bit tree can either be used as a mapping from strings to some type T or as a set of strings if T is void.   Source   Edit

Procs

func len[T](c: CritBitTree[T]): int {.inline.}
Returns the number of elements in c in O(1).

Example:

let c = ["key1", "key2"].toCritBitTree
doAssert c.len == 2
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func contains[T](c: CritBitTree[T]; key: string): bool {.inline.}
Returns true if c contains the given key.

Example:

var c: CritBitTree[void]
incl(c, "key")
doAssert c.contains("key")
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func hasKey[T](c: CritBitTree[T]; key: string): bool {.inline.}
Alias for contains.   Source   Edit
proc excl[T](c: var CritBitTree[T]; key: string)

Removes key (and its associated value) from the set c. If the key does not exist, nothing happens.

See also:

Example:

var c: CritBitTree[void]
incl(c, "key")
excl(c, "key")
doAssert not c.contains("key")
  Source   Edit
proc missingOrExcl[T](c: var CritBitTree[T]; key: string): bool

Returns true if c does not contain the given key. If the key does exist, c.excl(key) is performed.

See also:

Example:

block:
  var c: CritBitTree[void]
  doAssert c.missingOrExcl("key")
block:
  var c: CritBitTree[void]
  incl(c, "key")
  doAssert not c.missingOrExcl("key")
  doAssert not c.contains("key")
  Source   Edit
proc containsOrIncl[T](c: var CritBitTree[T]; key: string; val: T): bool

Returns true if c contains the given key. If the key does not exist, c[key] = val is performed.

See also:

Example:

block:
  var c: CritBitTree[int]
  doAssert not c.containsOrIncl("key", 42)
  doAssert c.contains("key")
block:
  var c: CritBitTree[int]
  incl(c, "key", 21)
  doAssert c.containsOrIncl("key", 42)
  doAssert c["key"] == 21
  Source   Edit
proc containsOrIncl(c: var CritBitTree[void]; key: string): bool {....raises: [],
    tags: [].}

Returns true if c contains the given key. If the key does not exist, it is inserted into c.

See also:

Example:

block:
  var c: CritBitTree[void]
  doAssert not c.containsOrIncl("key")
  doAssert c.contains("key")
block:
  var c: CritBitTree[void]
  incl(c, "key")
  doAssert c.containsOrIncl("key")
  Source   Edit
proc inc(c: var CritBitTree[int]; key: string; val: int = 1) {....raises: [],
    tags: [].}
Increments c[key] by val.

Example:

var c: CritBitTree[int]
c["key"] = 1
inc(c, "key")
doAssert c["key"] == 2
  Source   Edit
proc incl(c: var CritBitTree[void]; key: string) {....raises: [], tags: [].}

Includes key in c.

See also:

Example:

var c: CritBitTree[void]
incl(c, "key")
doAssert c.hasKey("key")
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proc incl[T](c: var CritBitTree[T]; key: string; val: T)

Inserts key with value val into c.

See also:

Example:

var c: CritBitTree[int]
incl(c, "key", 42)
doAssert c["key"] == 42
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proc `[]=`[T](c: var CritBitTree[T]; key: string; val: T)

Alias for incl.

See also:

  Source   Edit
func `[]`[T](c: CritBitTree[T]; key: string): T {.inline.}

Retrieves the value at c[key]. If key is not in t, the KeyError exception is raised. One can check with hasKey whether the key exists.

See also:

  Source   Edit
func `[]`[T](c: var CritBitTree[T]; key: string): var T {.inline.}

Retrieves the value at c[key]. The value can be modified. If key is not in t, the KeyError exception is raised.

See also:

  Source   Edit
func `$`[T](c: CritBitTree[T]): string
Turns c into a string representation.

Example:

doAssert $CritBitTree[int].default == "{:}"
doAssert $toCritBitTree({"key1": 1, "key2": 2}) == """{"key1": 1, "key2": 2}"""
doAssert $CritBitTree[void].default == "{}"
doAssert $toCritBitTree(["key1", "key2"]) == """{"key1", "key2"}"""
  Source   Edit
func commonPrefixLen[T](c: CritBitTree[T]): int {.inline.}
Returns the length of the longest common prefix of all keys in c. If c is empty, returns 0.

Example:

var c: CritBitTree[void]
doAssert c.commonPrefixLen == 0
incl(c, "key1")
doAssert c.commonPrefixLen == 4
incl(c, "key2")
doAssert c.commonPrefixLen == 3
  Source   Edit
proc toCritBitTree[T](pairs: openArray[(string, T)]): CritBitTree[T]
Creates a new CritBitTree that contains the given pairs.

Example:

doAssert {"a": "0", "b": "1", "c": "2"}.toCritBitTree is CritBitTree[string]
doAssert {"a": 0, "b": 1, "c": 2}.toCritBitTree is CritBitTree[int]
  Source   Edit
proc toCritBitTree(items: openArray[string]): CritBitTree[void] {....raises: [],
    tags: [].}
Creates a new CritBitTree that contains the given items.

Example:

doAssert ["a", "b", "c"].toCritBitTree is CritBitTree[void]
  Source   Edit

Iterators

iterator keys[T](c: CritBitTree[T]): string
Yields all keys in lexicographical order.

Example:

from std/sequtils import toSeq

let c = {"key1": 1, "key2": 2}.toCritBitTree
doAssert toSeq(c.keys) == @["key1", "key2"]
  Source   Edit
iterator values[T](c: CritBitTree[T]): T

Yields all values of c in the lexicographical order of the corresponding keys.

See also:

Example:

from std/sequtils import toSeq

let c = {"key1": 1, "key2": 2}.toCritBitTree
doAssert toSeq(c.values) == @[1, 2]
  Source   Edit
iterator mvalues[T](c: var CritBitTree[T]): var T

Yields all values of c in the lexicographical order of the corresponding keys. The values can be modified.

See also:

  Source   Edit
iterator items[T](c: CritBitTree[T]): string
Alias for keys.   Source   Edit
iterator pairs[T](c: CritBitTree[T]): tuple[key: string, val: T]

Yields all (key, value)-pairs of c in the lexicographical order of the corresponding keys.

See also:

Example:

from std/sequtils import toSeq

let c = {"key1": 1, "key2": 2}.toCritBitTree
doAssert toSeq(c.pairs) == @[(key: "key1", val: 1), (key: "key2", val: 2)]
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iterator mpairs[T](c: var CritBitTree[T]): tuple[key: string, val: var T]

Yields all (key, value)-pairs of c in the lexicographical order of the corresponding keys. The yielded values can be modified.

See also:

  Source   Edit
iterator keysWithPrefix[T](c: CritBitTree[T]; prefix: string): string
Yields all keys starting with prefix.

Example:

from std/sequtils import toSeq

let c = {"key1": 42, "key2": 43}.toCritBitTree
doAssert toSeq(c.keysWithPrefix("key")) == @["key1", "key2"]
  Source   Edit
iterator valuesWithPrefix[T](c: CritBitTree[T]; prefix: string): T

Yields all values of c starting with prefix of the corresponding keys.

See also:

Example:

from std/sequtils import toSeq

let c = {"key1": 42, "key2": 43}.toCritBitTree
doAssert toSeq(c.valuesWithPrefix("key")) == @[42, 43]
  Source   Edit
iterator mvaluesWithPrefix[T](c: var CritBitTree[T]; prefix: string): var T

Yields all values of c starting with prefix of the corresponding keys. The values can be modified.

See also:

  Source   Edit
iterator itemsWithPrefix[T](c: CritBitTree[T]; prefix: string): string
Alias for keysWithPrefix.   Source   Edit
iterator pairsWithPrefix[T](c: CritBitTree[T]; prefix: string): tuple[
    key: string, val: T]

Yields all (key, value)-pairs of c starting with prefix.

See also:

Example:

from std/sequtils import toSeq

let c = {"key1": 42, "key2": 43}.toCritBitTree
doAssert toSeq(c.pairsWithPrefix("key")) == @[(key: "key1", val: 42), (key: "key2", val: 43)]
  Source   Edit
iterator mpairsWithPrefix[T](c: var CritBitTree[T]; prefix: string): tuple[
    key: string, val: var T]

Yields all (key, value)-pairs of c starting with prefix. The yielded values can be modified.

See also:

  Source   Edit