std/tables

Source Edit

The tables module implements variants of an efficient hash table (also often named dictionary in other programming languages) that is a mapping from keys to values.

There are several different types of hash tables available:

• Table is the usual hash table,
• OrderedTable is like Table but remembers insertion order,
• CountTable is a mapping from a key to its number of occurrences

For consistency with every other data type in Nim these have value semantics, this means that = performs a copy of the hash table.

For ref semantics use their Ref variants: TableRef, OrderedTableRef, and CountTableRef.

To give an example, when a is a Table, then var b = a gives b as a new independent table. b is initialised with the contents of a. Changing b does not affect a and vice versa:

Example:

import std/tables
var
  a = {1: "one", 2: "two"}.toTable  # creates a Table
  b = a

assert a == b

b[3] = "three"
assert 3 notin a
assert 3 in b
assert a != b

On the other hand, when a is a TableRef instead, then changes to b also affect a. Both a and b ref the same data structure:

Example:

import std/tables
var
  a = {1: "one", 2: "two"}.newTable  # creates a TableRef
  b = a

assert a == b

b[3] = "three"

assert 3 in a
assert 3 in b
assert a == b

---

Basic usage

Table

Example:

import std/tables
from std/sequtils import zip

let
  names = ["John", "Paul", "George", "Ringo"]
  years = [1940, 1942, 1943, 1940]

var beatles = initTable[string, int]()

for pairs in zip(names, years):
  let (name, birthYear) = pairs
  beatles[name] = birthYear

assert beatles == {"George": 1943, "Ringo": 1940, "Paul": 1942, "John": 1940}.toTable


var beatlesByYear = initTable[int, seq[string]]()

for pairs in zip(years, names):
  let (birthYear, name) = pairs
  if not beatlesByYear.hasKey(birthYear):
    # if a key doesn't exist, we create one with an empty sequence
    # before we can add elements to it
    beatlesByYear[birthYear] = @[]
  beatlesByYear[birthYear].add(name)

assert beatlesByYear == {1940: @["John", "Ringo"], 1942: @["Paul"], 1943: @["George"]}.toTable

OrderedTable

OrderedTable is used when it is important to preserve the insertion order of keys.

Example:

import std/tables
let
  a = [('z', 1), ('y', 2), ('x', 3)]
  ot = a.toOrderedTable  # ordered tables

assert $ot == """{'z': 1, 'y': 2, 'x': 3}"""

CountTable

CountTable is useful for counting number of items of some container (e.g. string, sequence or array), as it is a mapping where the items are the keys, and their number of occurrences are the values. For that purpose toCountTable proc comes handy:

Example:

import std/tables
let myString = "abracadabra"
let letterFrequencies = toCountTable(myString)
assert $letterFrequencies == "{'a': 5, 'd': 1, 'b': 2, 'r': 2, 'c': 1}"

The same could have been achieved by manually iterating over a container and increasing each key's value with inc proc:

Example:

import std/tables
let myString = "abracadabra"
var letterFrequencies = initCountTable[char]()
for c in myString:
  letterFrequencies.inc(c)
assert $letterFrequencies == "{'d': 1, 'r': 2, 'c': 1, 'a': 5, 'b': 2}"

---

Hashing

If you are using simple standard types like int or string for the keys of the table you won't have any problems, but as soon as you try to use a more complex object as a key you will be greeted by a strange compiler error:

Error: type mismatch: got (Person)
but expected one of:
hashes.hash(x: openArray[A]): Hash
hashes.hash(x: int): Hash
hashes.hash(x: float): Hash

What is happening here is that the types used for table keys require to have a hash() proc which will convert them to a Hash value, and the compiler is listing all the hash functions it knows. Additionally there has to be a == operator that provides the same semantics as its corresponding hash proc.

After you add hash and == for your custom type everything will work. Currently, however, hash for objects is not defined, whereas system.== for objects does exist and performs a "deep" comparison (every field is compared) which is usually what you want. So in the following example implementing only hash suffices:

Example:

import std/tables
import std/hashes

type
  Person = object
    firstName, lastName: string

proc hash(x: Person): Hash =
  ## Piggyback on the already available string hash proc.
  ##
  ## Without this proc nothing works!
  result = x.firstName.hash !& x.lastName.hash
  result = !$result

var
  salaries = initTable[Person, int]()
  p1, p2: Person

p1.firstName = "Jon"
p1.lastName = "Ross"
salaries[p1] = 30_000

p2.firstName = "소진"
p2.lastName = "박"
salaries[p2] = 45_000

---

See also

• json module for table-like structure which allows heterogeneous members
• strtabs module for efficient hash tables mapping from strings to strings
• hashes module for helper functions for hashing

Imports

since, hashes, math, algorithm, outparams

Types

CountTable[A] = object

Hash table that counts the number of each key.

For creating an empty CountTable, use initCountTable proc.

Source Edit

CountTableRef[A] = ref CountTable[A]

Ref version of CountTable.

For creating a new empty CountTableRef, use newCountTable proc.

Source Edit

OrderedTable[A; B] = object

Hash table that remembers insertion order.

For creating an empty OrderedTable, use initOrderedTable proc.

Source Edit

OrderedTableRef[A; B] = ref OrderedTable[A, B]

Ref version of OrderedTable.

For creating a new empty OrderedTableRef, use newOrderedTable proc.

Source Edit

Table[A; B] = object

Generic hash table, consisting of a key-value pair.

data and counter are internal implementation details which can't be accessed.

For creating an empty Table, use initTable proc.

Source Edit

TableRef[A; B] = ref Table[A, B]

Ref version of Table.

For creating a new empty TableRef, use newTable proc.

Source Edit

Consts

defaultInitialSize = 32

Source Edit

Procs

proc `$`[A, B](t: OrderedTable[A, B]): string

The $ operator for ordered hash tables. Used internally when calling echo on a table. Source Edit

proc `$`[A, B](t: OrderedTableRef[A, B]): string

The $ operator for hash tables. Used internally when calling echo on a table. Source Edit

proc `$`[A, B](t: Table[A, B]): string

The $ operator for hash tables. Used internally when calling echo on a table. Source Edit

proc `$`[A, B](t: TableRef[A, B]): string

The $ operator for hash tables. Used internally when calling echo on a table. Source Edit

proc `$`[A](t: CountTable[A]): string

The $ operator for count tables. Used internally when calling echo on a table. Source Edit

proc `$`[A](t: CountTableRef[A]): string

The $ operator for count tables. Used internally when calling echo on a table. Source Edit

proc `==`[A, B](s, t: OrderedTable[A, B]): bool

The == operator for ordered hash tables. Returns true if both the content and the order are equal.

Example:

let
  a = {'a': 5, 'b': 9, 'c': 13}.toOrderedTable
  b = {'b': 9, 'c': 13, 'a': 5}.toOrderedTable
doAssert a != b

Source Edit

proc `==`[A, B](s, t: OrderedTableRef[A, B]): bool

The == operator for ordered hash tables. Returns true if either both tables are nil, or neither is nil and the content and the order of both are equal.

Example:

let
  a = {'a': 5, 'b': 9, 'c': 13}.newOrderedTable
  b = {'b': 9, 'c': 13, 'a': 5}.newOrderedTable
doAssert a != b

Source Edit

proc `==`[A, B](s, t: Table[A, B]): bool

The == operator for hash tables. Returns true if the content of both tables contains the same key-value pairs. Insert order does not matter.

Example:

let
  a = {'a': 5, 'b': 9, 'c': 13}.toTable
  b = {'b': 9, 'c': 13, 'a': 5}.toTable
doAssert a == b

Source Edit

proc `==`[A, B](s, t: TableRef[A, B]): bool

The == operator for hash tables. Returns true if either both tables are nil, or neither is nil and the content of both tables contains the same key-value pairs. Insert order does not matter.

Example:

let
  a = {'a': 5, 'b': 9, 'c': 13}.newTable
  b = {'b': 9, 'c': 13, 'a': 5}.newTable
doAssert a == b

Source Edit

proc `==`[A](s, t: CountTable[A]): bool

The == operator for count tables. Returns true if both tables contain the same keys with the same count. Insert order does not matter. Source Edit

proc `==`[A](s, t: CountTableRef[A]): bool

The == operator for count tables. Returns true if either both tables are nil, or neither is nil and both contain the same keys with the same count. Insert order does not matter. Source Edit

proc `[]`[A, B](t: OrderedTable[A, B]; key: A): lent B

Retrieves the value at t[key].

If key is not in t, the KeyError exception is raised. One can check with hasKey proc whether the key exists.

See also:

• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist
• getOrDefault proc to return a custom value if the key doesn't exist
• []= proc for inserting a new (key, value) pair in the table
• hasKey proc for checking if a key is in the table

Example:

let a = {'a': 5, 'b': 9}.toOrderedTable
doAssert a['a'] == 5
doAssertRaises(KeyError):
  echo a['z']

Source Edit

proc `[]`[A, B](t: OrderedTableRef[A, B]; key: A): var B

Retrieves the value at t[key].

If key is not in t, the KeyError exception is raised. One can check with hasKey proc whether the key exists.

See also:

• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist
• getOrDefault proc to return a custom value if the key doesn't exist
• []= proc for inserting a new (key, value) pair in the table
• hasKey proc for checking if a key is in the table

Example:

let a = {'a': 5, 'b': 9}.newOrderedTable
doAssert a['a'] == 5
doAssertRaises(KeyError):
  echo a['z']

Source Edit

proc `[]`[A, B](t: Table[A, B]; key: A): lent B

Retrieves the value at t[key].

If key is not in t, the KeyError exception is raised. One can check with hasKey proc whether the key exists.

See also:

• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist
• getOrDefault proc to return a custom value if the key doesn't exist
• []= proc for inserting a new (key, value) pair in the table
• hasKey proc for checking if a key is in the table

Example:

let a = {'a': 5, 'b': 9}.toTable
doAssert a['a'] == 5
doAssertRaises(KeyError):
  echo a['z']

Source Edit

proc `[]`[A, B](t: TableRef[A, B]; key: A): var B

Retrieves the value at t[key].

If key is not in t, the KeyError exception is raised. One can check with hasKey proc whether the key exists.

See also:

• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist
• getOrDefault proc to return a custom value if the key doesn't exist
• []= proc for inserting a new (key, value) pair in the table
• hasKey proc for checking if a key is in the table

Example:

let a = {'a': 5, 'b': 9}.newTable
doAssert a['a'] == 5
doAssertRaises(KeyError):
  echo a['z']

Source Edit

proc `[]`[A, B](t: var OrderedTable[A, B]; key: A): var B

Retrieves the value at t[key]. The value can be modified.

If key is not in t, the KeyError exception is raised.

See also:

• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist
• getOrDefault proc to return a custom value if the key doesn't exist
• []= proc for inserting a new (key, value) pair in the table
• hasKey proc for checking if a key is in the table

Source Edit

proc `[]`[A, B](t: var Table[A, B]; key: A): var B

Retrieves the value at t[key]. The value can be modified.

If key is not in t, the KeyError exception is raised.

See also:

• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist
• getOrDefault proc to return a custom value if the key doesn't exist
• []= proc for inserting a new (key, value) pair in the table
• hasKey proc for checking if a key is in the table

Source Edit

proc `[]`[A](t: CountTable[A]; key: A): int

Retrieves the value at t[key] if key is in t. Otherwise 0 is returned.

See also:

• getOrDefault to return a custom value if the key doesn't exist
• []= proc for inserting a new (key, value) pair in the table
• hasKey proc for checking if a key is in the table

Source Edit

proc `[]`[A](t: CountTableRef[A]; key: A): int

Retrieves the value at t[key] if key is in t. Otherwise 0 is returned.

See also:

• getOrDefault to return a custom value if the key doesn't exist
• inc proc to inc even if missing
• []= proc for inserting a new (key, value) pair in the table
• hasKey proc for checking if a key is in the table

Source Edit

proc `[]=`[A, B](t: OrderedTableRef[A, B]; key: A; val: sink B)

Inserts a (key, value) pair into t.

See also:

• [] proc for retrieving a value of a key
• hasKeyOrPut proc
• mgetOrPut proc
• del proc for removing a key from the table

Example:

var a = newOrderedTable[char, int]()
a['x'] = 7
a['y'] = 33
doAssert a == {'x': 7, 'y': 33}.newOrderedTable

Source Edit

proc `[]=`[A, B](t: TableRef[A, B]; key: A; val: sink B)

Inserts a (key, value) pair into t.

See also:

• [] proc for retrieving a value of a key
• hasKeyOrPut proc
• mgetOrPut proc
• del proc for removing a key from the table

Example:

var a = newTable[char, int]()
a['x'] = 7
a['y'] = 33
doAssert a == {'x': 7, 'y': 33}.newTable

Source Edit

proc `[]=`[A, B](t: var OrderedTable[A, B]; key: A; val: sink B)

Inserts a (key, value) pair into t.

See also:

• [] proc for retrieving a value of a key
• hasKeyOrPut proc
• mgetOrPut proc
• del proc for removing a key from the table

Example:

var a = initOrderedTable[char, int]()
a['x'] = 7
a['y'] = 33
doAssert a == {'x': 7, 'y': 33}.toOrderedTable

Source Edit

proc `[]=`[A, B](t: var Table[A, B]; key: A; val: sink B)

Inserts a (key, value) pair into t.

See also:

• [] proc for retrieving a value of a key
• hasKeyOrPut proc
• mgetOrPut proc
• del proc for removing a key from the table

Example:

var a = initTable[char, int]()
a['x'] = 7
a['y'] = 33
doAssert a == {'x': 7, 'y': 33}.toTable

Source Edit

proc `[]=`[A](t: CountTableRef[A]; key: A; val: int)

Inserts a (key, value) pair into t.

See also:

• [] proc for retrieving a value of a key
• inc proc for incrementing a value of a key

Source Edit

proc `[]=`[A](t: var CountTable[A]; key: A; val: int)

Inserts a (key, value) pair into t.

See also:

• [] proc for retrieving a value of a key
• inc proc for incrementing a value of a key

Source Edit

proc add[A, B](t: OrderedTableRef[A, B]; key: A; val: sink B) {....deprecated: "Deprecated since v1.4; it was more confusing than useful, use `[]=`".}

Deprecated: Deprecated since v1.4; it was more confusing than useful, use `[]=`

Puts a new (key, value) pair into t even if t[key] already exists.

This can introduce duplicate keys into the table!

Use []= proc for inserting a new (key, value) pair in the table without introducing duplicates.

Source Edit

proc add[A, B](t: TableRef[A, B]; key: A; val: sink B) {....deprecated: "Deprecated since v1.4; it was more confusing than useful, use `[]=`".}

Deprecated: Deprecated since v1.4; it was more confusing than useful, use `[]=`

Puts a new (key, value) pair into t even if t[key] already exists.

This can introduce duplicate keys into the table!

Use []= proc for inserting a new (key, value) pair in the table without introducing duplicates.

Source Edit

proc add[A, B](t: var OrderedTable[A, B]; key: A; val: sink B) {....deprecated: "Deprecated since v1.4; it was more confusing than useful, use `[]=`".}

Deprecated: Deprecated since v1.4; it was more confusing than useful, use `[]=`

Puts a new (key, value) pair into t even if t[key] already exists.

This can introduce duplicate keys into the table!

Use []= proc for inserting a new (key, value) pair in the table without introducing duplicates.

Source Edit

proc add[A, B](t: var Table[A, B]; key: A; val: sink B) {....deprecated: "Deprecated since v1.4; it was more confusing than useful, use `[]=`".}

Deprecated: Deprecated since v1.4; it was more confusing than useful, use `[]=`

Puts a new (key, value) pair into t even if t[key] already exists.

This can introduce duplicate keys into the table!

Use []= proc for inserting a new (key, value) pair in the table without introducing duplicates.

Source Edit

proc clear[A, B](t: OrderedTableRef[A, B])

Resets the table so that it is empty.

See also:

• del proc

Example:

var a = {'a': 5, 'b': 9, 'c': 13}.newOrderedTable
doAssert len(a) == 3
clear(a)
doAssert len(a) == 0

Source Edit

proc clear[A, B](t: TableRef[A, B])

Resets the table so that it is empty.

See also:

• del proc
• pop proc

Example:

var a = {'a': 5, 'b': 9, 'c': 13}.newTable
doAssert len(a) == 3
clear(a)
doAssert len(a) == 0

Source Edit

proc clear[A, B](t: var OrderedTable[A, B])

Resets the table so that it is empty.

See also:

• del proc
• pop proc

Example:

var a = {'a': 5, 'b': 9, 'c': 13}.toOrderedTable
doAssert len(a) == 3
clear(a)
doAssert len(a) == 0

Source Edit

proc clear[A, B](t: var Table[A, B])

Resets the table so that it is empty.

See also:

• del proc
• pop proc

Example:

var a = {'a': 5, 'b': 9, 'c': 13}.toTable
doAssert len(a) == 3
clear(a)
doAssert len(a) == 0

Source Edit

proc clear[A](t: CountTableRef[A])

Resets the table so that it is empty.

See also:

• del proc
• pop proc

Source Edit

proc clear[A](t: var CountTable[A])

Resets the table so that it is empty.

See also:

• del proc
• pop proc

Source Edit

proc contains[A, B](t: OrderedTable[A, B]; key: A): bool

Alias of hasKey proc for use with the in operator.

Example:

let a = {'a': 5, 'b': 9}.toOrderedTable
doAssert 'b' in a == true
doAssert a.contains('z') == false

Source Edit

proc contains[A, B](t: OrderedTableRef[A, B]; key: A): bool

Alias of hasKey proc for use with the in operator.

Example:

let a = {'a': 5, 'b': 9}.newOrderedTable
doAssert 'b' in a == true
doAssert a.contains('z') == false

Source Edit

proc contains[A, B](t: Table[A, B]; key: A): bool

Alias of hasKey proc for use with the in operator.

Example:

let a = {'a': 5, 'b': 9}.toTable
doAssert 'b' in a == true
doAssert a.contains('z') == false

Source Edit

proc contains[A, B](t: TableRef[A, B]; key: A): bool

Alias of hasKey proc for use with the in operator.

Example:

let a = {'a': 5, 'b': 9}.newTable
doAssert 'b' in a == true
doAssert a.contains('z') == false

Source Edit

proc contains[A](t: CountTable[A]; key: A): bool

Alias of hasKey proc for use with the in operator. Source Edit

proc contains[A](t: CountTableRef[A]; key: A): bool

Alias of hasKey proc for use with the in operator. Source Edit

proc del[A, B](t: OrderedTableRef[A, B]; key: A)

Deletes key from hash table t. Does nothing if the key does not exist.

See also:

• clear proc to empty the whole table

Example:

var a = {'a': 5, 'b': 9, 'c': 13}.newOrderedTable
a.del('a')
doAssert a == {'b': 9, 'c': 13}.newOrderedTable
a.del('z')
doAssert a == {'b': 9, 'c': 13}.newOrderedTable

Source Edit

proc del[A, B](t: TableRef[A, B]; key: A)

Deletes key from hash table t. Does nothing if the key does not exist.

Warning: If duplicate keys were added (via the now deprecated add proc), this may need to be called multiple times.

See also:

• pop proc
• clear proc to empty the whole table

Example:

var a = {'a': 5, 'b': 9, 'c': 13}.newTable
a.del('a')
doAssert a == {'b': 9, 'c': 13}.newTable
a.del('z')
doAssert a == {'b': 9, 'c': 13}.newTable

Source Edit

proc del[A, B](t: var OrderedTable[A, B]; key: A)

Deletes key from hash table t. Does nothing if the key does not exist.

O(n) complexity.

See also:

• pop proc
• clear proc to empty the whole table

Example:

var a = {'a': 5, 'b': 9, 'c': 13}.toOrderedTable
a.del('a')
doAssert a == {'b': 9, 'c': 13}.toOrderedTable
a.del('z')
doAssert a == {'b': 9, 'c': 13}.toOrderedTable

Source Edit

proc del[A, B](t: var Table[A, B]; key: A)

Deletes key from hash table t. Does nothing if the key does not exist.

Warning: If duplicate keys were added (via the now deprecated add proc), this may need to be called multiple times.

See also:

• pop proc
• clear proc to empty the whole table

Example:

var a = {'a': 5, 'b': 9, 'c': 13}.toTable
a.del('a')
doAssert a == {'b': 9, 'c': 13}.toTable
a.del('z')
doAssert a == {'b': 9, 'c': 13}.toTable

Source Edit

proc del[A](t: CountTableRef[A]; key: A)

Deletes key from table t. Does nothing if the key does not exist.

See also:

• pop proc
• clear proc to empty the whole table

Source Edit

proc del[A](t: var CountTable[A]; key: A)

Deletes key from table t. Does nothing if the key does not exist.

See also:

• pop proc
• clear proc to empty the whole table

Example:

var a = toCountTable("aabbbccccc")
a.del('b')
assert a == toCountTable("aaccccc")
a.del('b')
assert a == toCountTable("aaccccc")
a.del('c')
assert a == toCountTable("aa")

Source Edit

proc getOrDefault[A, B](t: OrderedTable[A, B]; key: A): B

Retrieves the value at t[key] if key is in t. Otherwise, the default initialization value for type B is returned (e.g. 0 for any integer type).

See also:

• [] proc for retrieving a value of a key
• hasKey proc
• hasKeyOrPut proc
• mgetOrPut proc
• getOrDefault proc to return a custom value if the key doesn't exist

Example:

let a = {'a': 5, 'b': 9}.toOrderedTable
doAssert a.getOrDefault('a') == 5
doAssert a.getOrDefault('z') == 0

Source Edit

proc getOrDefault[A, B](t: OrderedTable[A, B]; key: A; default: B): B

Retrieves the value at t[key] if key is in t. Otherwise, default is returned.

See also:

• [] proc for retrieving a value of a key
• hasKey proc
• hasKeyOrPut proc
• mgetOrPut proc
• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist

Example:

let a = {'a': 5, 'b': 9}.toOrderedTable
doAssert a.getOrDefault('a', 99) == 5
doAssert a.getOrDefault('z', 99) == 99

Source Edit

proc getOrDefault[A, B](t: OrderedTableRef[A, B]; key: A): B

Retrieves the value at t[key] if key is in t. Otherwise, the default initialization value for type B is returned (e.g. 0 for any integer type).

See also:

• [] proc for retrieving a value of a key
• hasKey proc
• hasKeyOrPut proc
• mgetOrPut proc
• getOrDefault proc to return a custom value if the key doesn't exist

Example:

let a = {'a': 5, 'b': 9}.newOrderedTable
doAssert a.getOrDefault('a') == 5
doAssert a.getOrDefault('z') == 0

Source Edit

proc getOrDefault[A, B](t: OrderedTableRef[A, B]; key: A; default: B): B

Retrieves the value at t[key] if key is in t. Otherwise, default is returned.

See also:

• [] proc for retrieving a value of a key
• hasKey proc
• hasKeyOrPut proc
• mgetOrPut proc
• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist

Example:

let a = {'a': 5, 'b': 9}.newOrderedTable
doAssert a.getOrDefault('a', 99) == 5
doAssert a.getOrDefault('z', 99) == 99

Source Edit

proc getOrDefault[A, B](t: Table[A, B]; key: A): B

Retrieves the value at t[key] if key is in t. Otherwise, the default initialization value for type B is returned (e.g. 0 for any integer type).

See also:

• [] proc for retrieving a value of a key
• hasKey proc
• hasKeyOrPut proc
• mgetOrPut proc
• getOrDefault proc to return a custom value if the key doesn't exist

Example:

let a = {'a': 5, 'b': 9}.toTable
doAssert a.getOrDefault('a') == 5
doAssert a.getOrDefault('z') == 0

Source Edit

proc getOrDefault[A, B](t: Table[A, B]; key: A; default: B): B

Retrieves the value at t[key] if key is in t. Otherwise, default is returned.

See also:

• [] proc for retrieving a value of a key
• hasKey proc
• hasKeyOrPut proc
• mgetOrPut proc
• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist

Example:

let a = {'a': 5, 'b': 9}.toTable
doAssert a.getOrDefault('a', 99) == 5
doAssert a.getOrDefault('z', 99) == 99

Source Edit

proc getOrDefault[A, B](t: TableRef[A, B]; key: A): B

Retrieves the value at t[key] if key is in t. Otherwise, the default initialization value for type B is returned (e.g. 0 for any integer type).

See also:

• [] proc for retrieving a value of a key
• hasKey proc
• hasKeyOrPut proc
• mgetOrPut proc
• getOrDefault proc to return a custom value if the key doesn't exist

Example:

let a = {'a': 5, 'b': 9}.newTable
doAssert a.getOrDefault('a') == 5
doAssert a.getOrDefault('z') == 0

Source Edit

proc getOrDefault[A, B](t: TableRef[A, B]; key: A; default: B): B

Retrieves the value at t[key] if key is in t. Otherwise, default is returned.

See also:

• [] proc for retrieving a value of a key
• hasKey proc
• hasKeyOrPut proc
• mgetOrPut proc
• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist

Example:

let a = {'a': 5, 'b': 9}.newTable
doAssert a.getOrDefault('a', 99) == 5
doAssert a.getOrDefault('z', 99) == 99

Source Edit

proc getOrDefault[A](t: CountTable[A]; key: A; default: int = 0): int

Retrieves the value at t[key] if key is in t. Otherwise, the integer value of default is returned.

See also:

• [] proc for retrieving a value of a key
• hasKey proc for checking if a key is in the table

Source Edit

proc getOrDefault[A](t: CountTableRef[A]; key: A; default: int): int

Retrieves the value at t[key] if key is in t. Otherwise, the integer value of default is returned.

See also:

• [] proc for retrieving a value of a key
• hasKey proc for checking if a key is in the table

Source Edit

proc hash[K, V](s: OrderedTable[K, V]): Hash

Source Edit

proc hash[K, V](s: Table[K, V]): Hash

Source Edit

proc hash[V](s: CountTable[V]): Hash

Source Edit

proc hasKey[A, B](t: OrderedTable[A, B]; key: A): bool

Returns true if key is in the table t.

See also:

• contains proc for use with the in operator
• [] proc for retrieving a value of a key
• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist
• getOrDefault proc to return a custom value if the key doesn't exist

Example:

let a = {'a': 5, 'b': 9}.toOrderedTable
doAssert a.hasKey('a') == true
doAssert a.hasKey('z') == false

Source Edit

proc hasKey[A, B](t: OrderedTableRef[A, B]; key: A): bool

Returns true if key is in the table t.

See also:

• contains proc for use with the in operator
• [] proc for retrieving a value of a key
• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist
• getOrDefault proc to return a custom value if the key doesn't exist

Example:

let a = {'a': 5, 'b': 9}.newOrderedTable
doAssert a.hasKey('a') == true
doAssert a.hasKey('z') == false

Source Edit

proc hasKey[A, B](t: Table[A, B]; key: A): bool

Returns true if key is in the table t.

See also:

• contains proc for use with the in operator
• [] proc for retrieving a value of a key
• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist
• getOrDefault proc to return a custom value if the key doesn't exist

Example:

let a = {'a': 5, 'b': 9}.toTable
doAssert a.hasKey('a') == true
doAssert a.hasKey('z') == false

Source Edit

proc hasKey[A, B](t: TableRef[A, B]; key: A): bool

Returns true if key is in the table t.

See also:

• contains proc for use with the in operator
• [] proc for retrieving a value of a key
• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist
• getOrDefault proc to return a custom value if the key doesn't exist

Example:

let a = {'a': 5, 'b': 9}.newTable
doAssert a.hasKey('a') == true
doAssert a.hasKey('z') == false

Source Edit

proc hasKey[A](t: CountTable[A]; key: A): bool

Returns true if key is in the table t.

See also:

• contains proc for use with the in operator
• [] proc for retrieving a value of a key
• getOrDefault proc to return a custom value if the key doesn't exist

Source Edit

proc hasKey[A](t: CountTableRef[A]; key: A): bool

Returns true if key is in the table t.

See also:

• contains proc for use with the in operator
• [] proc for retrieving a value of a key
• getOrDefault proc to return a custom value if the key doesn't exist

Source Edit

proc hasKeyOrPut[A, B](t: OrderedTableRef[A, B]; key: A; val: B): bool

Returns true if key is in the table, otherwise inserts value.

See also:

• hasKey proc
• [] proc for retrieving a value of a key
• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist
• getOrDefault proc to return a custom value if the key doesn't exist

Example:

var a = {'a': 5, 'b': 9}.newOrderedTable
if a.hasKeyOrPut('a', 50):
  a['a'] = 99
if a.hasKeyOrPut('z', 50):
  a['z'] = 99
doAssert a == {'a': 99, 'b': 9, 'z': 50}.newOrderedTable

Source Edit

proc hasKeyOrPut[A, B](t: TableRef[A, B]; key: A; val: B): bool

Returns true if key is in the table, otherwise inserts value.

See also:

• hasKey proc
• [] proc for retrieving a value of a key
• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist
• getOrDefault proc to return a custom value if the key doesn't exist

Example:

var a = {'a': 5, 'b': 9}.newTable
if a.hasKeyOrPut('a', 50):
  a['a'] = 99
if a.hasKeyOrPut('z', 50):
  a['z'] = 99
doAssert a == {'a': 99, 'b': 9, 'z': 50}.newTable

Source Edit

proc hasKeyOrPut[A, B](t: var OrderedTable[A, B]; key: A; val: B): bool

Returns true if key is in the table, otherwise inserts value.

See also:

• hasKey proc
• [] proc for retrieving a value of a key
• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist
• getOrDefault proc to return a custom value if the key doesn't exist

Example:

var a = {'a': 5, 'b': 9}.toOrderedTable
if a.hasKeyOrPut('a', 50):
  a['a'] = 99
if a.hasKeyOrPut('z', 50):
  a['z'] = 99
doAssert a == {'a': 99, 'b': 9, 'z': 50}.toOrderedTable

Source Edit

proc hasKeyOrPut[A, B](t: var Table[A, B]; key: A; val: B): bool

Returns true if key is in the table, otherwise inserts value.

See also:

• hasKey proc
• [] proc for retrieving a value of a key
• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist
• getOrDefault proc to return a custom value if the key doesn't exist

Example:

var a = {'a': 5, 'b': 9}.toTable
if a.hasKeyOrPut('a', 50):
  a['a'] = 99
if a.hasKeyOrPut('z', 50):
  a['z'] = 99
doAssert a == {'a': 99, 'b': 9, 'z': 50}.toTable

Source Edit

proc inc[A](t: CountTableRef[A]; key: A; val = 1)

Source Edit

proc inc[A](t: var CountTable[A]; key: A; val = 1)

Source Edit

proc indexBy[A, B, C](collection: A; index: proc (x: B): C): Table[C, B]

Index the collection with the proc provided. Source Edit

proc initCountTable[A](initialSize = defaultInitialSize): CountTable[A]

Creates a new count table that is empty.

Starting from Nim v0.20, tables are initialized by default and it is not necessary to call this function explicitly.

See also:

• toCountTable proc
• newCountTable proc for creating a CountTableRef

Source Edit

proc initOrderedTable[A, B](initialSize = defaultInitialSize): OrderedTable[A, B]

Creates a new ordered hash table that is empty.

Starting from Nim v0.20, tables are initialized by default and it is not necessary to call this function explicitly.

See also:

• toOrderedTable proc
• newOrderedTable proc for creating an OrderedTableRef

Example:

let
  a = initOrderedTable[int, string]()
  b = initOrderedTable[char, seq[int]]()

Source Edit

proc initTable[A, B](initialSize = defaultInitialSize): Table[A, B]

Creates a new hash table that is empty.

Starting from Nim v0.20, tables are initialized by default and it is not necessary to call this function explicitly.

See also:

• toTable proc
• newTable proc for creating a TableRef

Example:

let
  a = initTable[int, string]()
  b = initTable[char, seq[int]]()

Source Edit

proc largest[A](t: CountTable[A]): tuple[key: A, val: int]

Returns the (key, value) pair with the largest val. Efficiency: O(n)

See also:

• smallest proc

Source Edit

proc largest[A](t: CountTableRef[A]): tuple[key: A, val: int]

Returns the (key, value) pair with the largest val. Efficiency: O(n)

See also:

• smallest proc

Source Edit

proc len[A, B](t: OrderedTable[A, B]): int {.inline.}

Returns the number of keys in t.

Example:

let a = {'a': 5, 'b': 9}.toOrderedTable
doAssert len(a) == 2

Source Edit

proc len[A, B](t: OrderedTableRef[A, B]): int {.inline.}

Returns the number of keys in t.

Example:

let a = {'a': 5, 'b': 9}.newOrderedTable
doAssert len(a) == 2

Source Edit

proc len[A, B](t: Table[A, B]): int

Returns the number of keys in t.

Example:

let a = {'a': 5, 'b': 9}.toTable
doAssert len(a) == 2

Source Edit

proc len[A, B](t: TableRef[A, B]): int

Returns the number of keys in t.

Example:

let a = {'a': 5, 'b': 9}.newTable
doAssert len(a) == 2

Source Edit

proc len[A](t: CountTable[A]): int

Returns the number of keys in t. Source Edit

proc len[A](t: CountTableRef[A]): int

Returns the number of keys in t. Source Edit

proc merge[A](s, t: CountTableRef[A])

Merges the second table into the first one.

Example:

let
  a = newCountTable("aaabbc")
  b = newCountTable("bcc")
a.merge(b)
doAssert a == newCountTable("aaabbbccc")

Source Edit

proc merge[A](s: var CountTable[A]; t: CountTable[A])

Merges the second table into the first one (must be declared as var).

Example:

var a = toCountTable("aaabbc")
let b = toCountTable("bcc")
a.merge(b)
doAssert a == toCountTable("aaabbbccc")

Source Edit

proc mgetOrPut[A, B](t: OrderedTableRef[A, B]; key: A): var B

Retrieves the value at t[key] or puts the default initialization value for type B (e.g. 0 for any integer type).

Example:

var a = {'a': 5}.toOrderedTable
doAssert a.mgetOrPut('a') == 5
a.mgetOrPut('z').inc
doAssert a == {'a': 5, 'z': 1}.toOrderedTable

Source Edit

proc mgetOrPut[A, B](t: OrderedTableRef[A, B]; key: A; val: B): var B

Retrieves value at t[key] or puts val if not present, either way returning a value which can be modified.

See also:

• [] proc for retrieving a value of a key
• hasKey proc
• hasKeyOrPut proc
• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist
• getOrDefault proc to return a custom value if the key doesn't exist

Example:

var a = {'a': 5, 'b': 9}.newOrderedTable
doAssert a.mgetOrPut('a', 99) == 5
doAssert a.mgetOrPut('z', 99) == 99
doAssert a == {'a': 5, 'b': 9, 'z': 99}.newOrderedTable

Source Edit

proc mgetOrPut[A, B](t: TableRef[A, B]; key: A): var B

Retrieves the value at t[key] or puts the default initialization value for type B (e.g. 0 for any integer type).

Example:

var a = {'a': 5}.newTable
doAssert a.mgetOrPut('a') == 5
a.mgetOrPut('z').inc
doAssert a == {'a': 5, 'z': 1}.newTable

Source Edit

proc mgetOrPut[A, B](t: TableRef[A, B]; key: A; val: B): var B

Retrieves value at t[key] or puts val if not present, either way returning a value which can be modified.

Note that while the value returned is of type var B, it is easy to accidentally create an copy of the value at t[key]. Remember that seqs and strings are value types, and therefore cannot be copied into a separate variable for modification. See the example below.

See also:

• [] proc for retrieving a value of a key
• hasKey proc
• hasKeyOrPut proc
• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist
• getOrDefault proc to return a custom value if the key doesn't exist

Example:

var a = {'a': 5, 'b': 9}.newTable
doAssert a.mgetOrPut('a', 99) == 5
doAssert a.mgetOrPut('z', 99) == 99
doAssert a == {'a': 5, 'b': 9, 'z': 99}.newTable

# An example of accidentally creating a copy
var t = newTable[int, seq[int]]()
# In this example, we expect t[10] to be modified,
# but it is not.
var copiedSeq = t.mgetOrPut(10, @[10])
copiedSeq.add(20)
doAssert t[10] == @[10]
# Correct
t.mgetOrPut(25, @[25]).add(35)
doAssert t[25] == @[25, 35]

Source Edit

proc mgetOrPut[A, B](t: var OrderedTable[A, B]; key: A): var B

Retrieves the value at t[key] or puts the default initialization value for type B (e.g. 0 for any integer type).

Example:

var a = {'a': 5}.toOrderedTable
doAssert a.mgetOrPut('a') == 5
a.mgetOrPut('z').inc
doAssert a == {'a': 5, 'z': 1}.toOrderedTable

Source Edit

proc mgetOrPut[A, B](t: var OrderedTable[A, B]; key: A; val: B): var B

Retrieves value at t[key] or puts val if not present, either way returning a value which can be modified.

See also:

• [] proc for retrieving a value of a key
• hasKey proc
• hasKeyOrPut proc
• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist
• getOrDefault proc to return a custom value if the key doesn't exist

Example:

var a = {'a': 5, 'b': 9}.toOrderedTable
doAssert a.mgetOrPut('a', 99) == 5
doAssert a.mgetOrPut('z', 99) == 99
doAssert a == {'a': 5, 'b': 9, 'z': 99}.toOrderedTable

Source Edit

proc mgetOrPut[A, B](t: var Table[A, B]; key: A): var B

Retrieves the value at t[key] or puts the default initialization value for type B (e.g. 0 for any integer type).

Example:

var a = {'a': 5}.newTable
doAssert a.mgetOrPut('a') == 5
a.mgetOrPut('z').inc
doAssert a == {'a': 5, 'z': 1}.newTable

Source Edit

proc mgetOrPut[A, B](t: var Table[A, B]; key: A; val: B): var B

Retrieves value at t[key] or puts val if not present, either way returning a value which can be modified.

Note that while the value returned is of type var B, it is easy to accidentally create a copy of the value at t[key]. Remember that seqs and strings are value types, and therefore cannot be copied into a separate variable for modification. See the example below.

See also:

• [] proc for retrieving a value of a key
• hasKey proc
• hasKeyOrPut proc
• getOrDefault proc to return a default value (e.g. zero for int) if the key doesn't exist
• getOrDefault proc to return a custom value if the key doesn't exist

Example:

var a = {'a': 5, 'b': 9}.toTable
doAssert a.mgetOrPut('a', 99) == 5
doAssert a.mgetOrPut('z', 99) == 99
doAssert a == {'a': 5, 'b': 9, 'z': 99}.toTable

# An example of accidentally creating a copy
var t = initTable[int, seq[int]]()
# In this example, we expect t[10] to be modified,
# but it is not.
var copiedSeq = t.mgetOrPut(10, @[10])
copiedSeq.add(20)
doAssert t[10] == @[10]
# Correct
t.mgetOrPut(25, @[25]).add(35)
doAssert t[25] == @[25, 35]

Source Edit

proc newCountTable[A](initialSize = defaultInitialSize): CountTableRef[A]

Creates a new ref count table that is empty.

See also:

• newCountTable proc for creating a CountTableRef from a collection
• initCountTable proc for creating a CountTable

Source Edit

proc newCountTable[A](keys: openArray[A]): CountTableRef[A]

Creates a new ref count table with every member of a container keys having a count of how many times it occurs in that container. Source Edit

proc newOrderedTable[A, B](initialSize = defaultInitialSize): OrderedTableRef[A,
    B]

Creates a new ordered ref hash table that is empty.

See also:

• newOrderedTable proc for creating an OrderedTableRef from a collection of (key, value) pairs
• initOrderedTable proc for creating an OrderedTable

Example:

let
  a = newOrderedTable[int, string]()
  b = newOrderedTable[char, seq[int]]()

Source Edit

proc newOrderedTable[A, B](pairs: openArray[(A, B)]): OrderedTableRef[A, B]

Creates a new ordered ref hash table that contains the given pairs.

pairs is a container consisting of (key, value) tuples.

See also:

• newOrderedTable proc
• toOrderedTable proc for an OrderedTable version

Example:

let a = [('a', 5), ('b', 9)]
let b = newOrderedTable(a)
assert b == {'a': 5, 'b': 9}.newOrderedTable

Source Edit

proc newTable[A, B](initialSize = defaultInitialSize): TableRef[A, B]

Creates a new ref hash table that is empty.

See also:

• newTable proc for creating a TableRef from a collection of (key, value) pairs
• initTable proc for creating a Table

Example:

let
  a = newTable[int, string]()
  b = newTable[char, seq[int]]()

Source Edit

proc newTable[A, B](pairs: openArray[(A, B)]): TableRef[A, B]

Creates a new ref hash table that contains the given pairs.

pairs is a container consisting of (key, value) tuples.

See also:

• newTable proc
• toTable proc for a Table version

Example:

let a = [('a', 5), ('b', 9)]
let b = newTable(a)
assert b == {'a': 5, 'b': 9}.newTable

Source Edit

proc newTableFrom[A, B, C](collection: A; index: proc (x: B): C): TableRef[C, B]

Index the collection with the proc provided. Source Edit

proc pop[A, B](t: OrderedTableRef[A, B]; key: A; val: var B): bool

Deletes the key from the table. Returns true, if the key existed, and sets val to the mapping of the key. Otherwise, returns false, and the val is unchanged.

See also:

• del proc
• clear proc to empty the whole table

Example:

var
  a = {'c': 5, 'b': 9, 'a': 13}.newOrderedTable
  i: int
doAssert a.pop('b', i) == true
doAssert a == {'c': 5, 'a': 13}.newOrderedTable
doAssert i == 9
i = 0
doAssert a.pop('z', i) == false
doAssert a == {'c': 5, 'a': 13}.newOrderedTable
doAssert i == 0

Source Edit

proc pop[A, B](t: TableRef[A, B]; key: A; val: var B): bool

Deletes the key from the table. Returns true, if the key existed, and sets val to the mapping of the key. Otherwise, returns false, and the val is unchanged.

Warning: If duplicate keys were added (via the now deprecated add proc), this may need to be called multiple times.

See also:

• del proc
• clear proc to empty the whole table

Example:

var
  a = {'a': 5, 'b': 9, 'c': 13}.newTable
  i: int
doAssert a.pop('b', i) == true
doAssert a == {'a': 5, 'c': 13}.newTable
doAssert i == 9
i = 0
doAssert a.pop('z', i) == false
doAssert a == {'a': 5, 'c': 13}.newTable
doAssert i == 0

Source Edit

proc pop[A, B](t: var OrderedTable[A, B]; key: A; val: var B): bool

Deletes the key from the table. Returns true, if the key existed, and sets val to the mapping of the key. Otherwise, returns false, and the val is unchanged.

O(n) complexity.

See also:

• del proc
• clear proc to empty the whole table

Example:

var
  a = {'c': 5, 'b': 9, 'a': 13}.toOrderedTable
  i: int
doAssert a.pop('b', i) == true
doAssert a == {'c': 5, 'a': 13}.toOrderedTable
doAssert i == 9
i = 0
doAssert a.pop('z', i) == false
doAssert a == {'c': 5, 'a': 13}.toOrderedTable
doAssert i == 0

Source Edit

proc pop[A, B](t: var Table[A, B]; key: A; val: var B): bool

Deletes the key from the table. Returns true, if the key existed, and sets val to the mapping of the key. Otherwise, returns false, and the val is unchanged.

Warning: If duplicate keys were added (via the now deprecated add proc), this may need to be called multiple times.

See also:

• del proc
• clear proc to empty the whole table

Example:

var
  a = {'a': 5, 'b': 9, 'c': 13}.toTable
  i: int
doAssert a.pop('b', i) == true
doAssert a == {'a': 5, 'c': 13}.toTable
doAssert i == 9
i = 0
doAssert a.pop('z', i) == false
doAssert a == {'a': 5, 'c': 13}.toTable
doAssert i == 0

Source Edit

proc pop[A](t: CountTableRef[A]; key: A; val: var int): bool

Deletes the key from the table. Returns true, if the key existed, and sets val to the mapping of the key. Otherwise, returns false, and the val is unchanged.

See also:

• del proc
• clear proc to empty the whole table

Source Edit

proc pop[A](t: var CountTable[A]; key: A; val: var int): bool

Deletes the key from the table. Returns true, if the key existed, and sets val to the mapping of the key. Otherwise, returns false, and the val is unchanged.

See also:

• del proc
• clear proc to empty the whole table

Example:

var a = toCountTable("aabbbccccc")
var i = 0
assert a.pop('b', i)
assert i == 3
i = 99
assert not a.pop('b', i)
assert i == 99

Source Edit

proc smallest[A](t: CountTable[A]): tuple[key: A, val: int]

Returns the (key, value) pair with the smallest val. Efficiency: O(n)

See also:

• largest proc

Source Edit

proc smallest[A](t: CountTableRef[A]): tuple[key: A, val: int]

Returns the (key, value) pair with the smallest val. Efficiency: O(n)

See also:

• largest proc

Source Edit

proc sort[A, B](t: OrderedTableRef[A, B]; cmp: proc (x, y: (A, B)): int;
                order = SortOrder.Ascending) {.effectsOf: cmp.}

Sorts t according to the function cmp.

This modifies the internal list that kept the insertion order, so insertion order is lost after this call but key lookup and insertions remain possible after sort (in contrast to the sort proc for count tables).

Example:

import std/[algorithm]
var a = newOrderedTable[char, int]()
for i, c in "cab":
  a[c] = 10*i
doAssert a == {'c': 0, 'a': 10, 'b': 20}.newOrderedTable
a.sort(system.cmp)
doAssert a == {'a': 10, 'b': 20, 'c': 0}.newOrderedTable
a.sort(system.cmp, order = SortOrder.Descending)
doAssert a == {'c': 0, 'b': 20, 'a': 10}.newOrderedTable

Source Edit

proc sort[A, B](t: var OrderedTable[A, B]; cmp: proc (x, y: (A, B)): int;
                order = SortOrder.Ascending) {.effectsOf: cmp.}

Sorts t according to the function cmp.

This modifies the internal list that kept the insertion order, so insertion order is lost after this call but key lookup and insertions remain possible after sort (in contrast to the sort proc for count tables).

Example:

import std/[algorithm]
var a = initOrderedTable[char, int]()
for i, c in "cab":
  a[c] = 10*i
doAssert a == {'c': 0, 'a': 10, 'b': 20}.toOrderedTable
a.sort(system.cmp)
doAssert a == {'a': 10, 'b': 20, 'c': 0}.toOrderedTable
a.sort(system.cmp, order = SortOrder.Descending)
doAssert a == {'c': 0, 'b': 20, 'a': 10}.toOrderedTable

Source Edit

proc sort[A](t: CountTableRef[A]; order = SortOrder.Descending)

Sorts the count table so that, by default, 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.

Source Edit

proc sort[A](t: var CountTable[A]; order = SortOrder.Descending)

Sorts the count table so that, by default, the entry with the highest counter comes first.

Warning: This is destructive! Once sorted, you must not modify t afterwards!

You can use the iterators pairs, keys, and values to iterate over t in the sorted order.

Example:

import std/[algorithm, sequtils]
var a = toCountTable("abracadabra")
doAssert a == "aaaaabbrrcd".toCountTable
a.sort()
doAssert toSeq(a.values) == @[5, 2, 2, 1, 1]
a.sort(SortOrder.Ascending)
doAssert toSeq(a.values) == @[1, 1, 2, 2, 5]

Source Edit

proc take[A, B](t: TableRef[A, B]; key: A; val: var B): bool {.inline.}

Alias for:

• pop proc

Source Edit

proc take[A, B](t: var Table[A, B]; key: A; val: var B): bool {.inline.}

Alias for:

• pop proc

Source Edit

proc toCountTable[A](keys: openArray[A]): CountTable[A]

Creates a new count table with every member of a container keys having a count of how many times it occurs in that container. Source Edit

proc toOrderedTable[A, B](pairs: openArray[(A, B)]): OrderedTable[A, B]

Creates a new ordered hash table that contains the given pairs.

pairs is a container consisting of (key, value) tuples.

See also:

• initOrderedTable proc
• newOrderedTable proc for an OrderedTableRef version

Example:

let a = [('a', 5), ('b', 9)]
let b = toOrderedTable(a)
assert b == {'a': 5, 'b': 9}.toOrderedTable

Source Edit

proc toTable[A, B](pairs: openArray[(A, B)]): Table[A, B]

Creates a new hash table that contains the given pairs.

pairs is a container consisting of (key, value) tuples.

See also:

• initTable proc
• newTable proc for a TableRef version

Example:

let a = [('a', 5), ('b', 9)]
let b = toTable(a)
assert b == {'a': 5, 'b': 9}.toTable

Source Edit

Iterators

iterator allValues[A, B](t: Table[A, B]; key: A): B {....deprecated: "Deprecated since v1.4; tables with duplicated keys are deprecated".}

Deprecated: Deprecated since v1.4; tables with duplicated keys are deprecated

Iterates over any value in the table t that belongs to the given key.

Used if you have a table with duplicate keys (as a result of using add proc).

Example:

import std/[sequtils, algorithm]

var a = {'a': 3, 'b': 5}.toTable
for i in 1..3: a.add('z', 10*i)
doAssert toSeq(a.pairs).sorted == @[('a', 3), ('b', 5), ('z', 10), ('z', 20), ('z', 30)]
doAssert sorted(toSeq(a.allValues('z'))) == @[10, 20, 30]

Source Edit

iterator keys[A, B](t: OrderedTable[A, B]): lent A

Iterates over any key in the table t in insertion order.

See also:

• pairs iterator
• values iterator

Example:

var a = {
  'o': @[1, 5, 7, 9],
  'e': @[2, 4, 6, 8]
  }.toOrderedTable
for k in a.keys:
  a[k].add(99)
doAssert a == {'o': @[1, 5, 7, 9, 99],
               'e': @[2, 4, 6, 8, 99]}.toOrderedTable

Source Edit

iterator keys[A, B](t: OrderedTableRef[A, B]): lent A

Iterates over any key in the table t in insertion order.

See also:

• pairs iterator
• values iterator

Example:

let a = {
  'o': @[1, 5, 7, 9],
  'e': @[2, 4, 6, 8]
  }.newOrderedTable
for k in a.keys:
  a[k].add(99)
doAssert a == {'o': @[1, 5, 7, 9, 99], 'e': @[2, 4, 6, 8,
    99]}.newOrderedTable

Source Edit

iterator keys[A, B](t: Table[A, B]): lent A

Iterates over any key in the table t.

See also:

• pairs iterator
• values iterator

Example:

var a = {
  'o': @[1, 5, 7, 9],
  'e': @[2, 4, 6, 8]
  }.toTable
for k in a.keys:
  a[k].add(99)
doAssert a == {'e': @[2, 4, 6, 8, 99], 'o': @[1, 5, 7, 9, 99]}.toTable

Source Edit

iterator keys[A, B](t: TableRef[A, B]): lent A

Iterates over any key in the table t.

See also:

• pairs iterator
• values iterator

Example:

let a = {
  'o': @[1, 5, 7, 9],
  'e': @[2, 4, 6, 8]
  }.newTable
for k in a.keys:
  a[k].add(99)
doAssert a == {'e': @[2, 4, 6, 8, 99], 'o': @[1, 5, 7, 9, 99]}.newTable

Source Edit

iterator keys[A](t: CountTable[A]): lent A

Iterates over any key in the table t.

See also:

• pairs iterator
• values iterator

Example:

var a = toCountTable("abracadabra")
for k in keys(a):
  a[k] = 2
doAssert a == toCountTable("aabbccddrr")

Source Edit

iterator keys[A](t: CountTableRef[A]): A

Iterates over any key in the table t.

See also:

• pairs iterator
• values iterator

Example:

let a = newCountTable("abracadabra")
for k in keys(a):
  a[k] = 2
doAssert a == newCountTable("aabbccddrr")

Source Edit

iterator mpairs[A, B](t: OrderedTableRef[A, B]): (A, var B)

Iterates over any (key, value) pair in the table t in insertion order. The values can be modified.

See also:

• pairs iterator
• mvalues iterator

Example:

let a = {
  'o': @[1, 5, 7, 9],
  'e': @[2, 4, 6, 8]
  }.newOrderedTable
for k, v in a.mpairs:
  v.add(v[0] + 10)
doAssert a == {'o': @[1, 5, 7, 9, 11],
               'e': @[2, 4, 6, 8, 12]}.newOrderedTable

Source Edit

iterator mpairs[A, B](t: TableRef[A, B]): (A, var B)

Iterates over any (key, value) pair in the table t. The values can be modified.

See also:

• pairs iterator
• mvalues iterator

Example:

let a = {
  'o': @[1, 5, 7, 9],
  'e': @[2, 4, 6, 8]
  }.newTable
for k, v in a.mpairs:
  v.add(v[0] + 10)
doAssert a == {'e': @[2, 4, 6, 8, 12], 'o': @[1, 5, 7, 9, 11]}.newTable

Source Edit

iterator mpairs[A, B](t: var OrderedTable[A, B]): (A, var B)

Iterates over any (key, value) pair in the table t (must be declared as var) in insertion order. The values can be modified.

See also:

• pairs iterator
• mvalues iterator

Example:

var a = {
  'o': @[1, 5, 7, 9],
  'e': @[2, 4, 6, 8]
  }.toOrderedTable
for k, v in a.mpairs:
  v.add(v[0] + 10)
doAssert a == {'o': @[1, 5, 7, 9, 11],
               'e': @[2, 4, 6, 8, 12]}.toOrderedTable

Source Edit

iterator mpairs[A, B](t: var Table[A, B]): (A, var B)

Iterates over any (key, value) pair in the table t (must be declared as var). The values can be modified.

See also:

• pairs iterator
• mvalues iterator

Example:

var a = {
  'o': @[1, 5, 7, 9],
  'e': @[2, 4, 6, 8]
  }.toTable
for k, v in a.mpairs:
  v.add(v[0] + 10)
doAssert a == {'e': @[2, 4, 6, 8, 12], 'o': @[1, 5, 7, 9, 11]}.toTable

Source Edit

iterator mpairs[A](t: CountTableRef[A]): (A, var int)

Iterates over any (key, value) pair in the table t. The values can be modified.

See also:

• pairs iterator
• mvalues iterator

Example:

let a = newCountTable("abracadabra")
for k, v in mpairs(a):
  v = 2
doAssert a == newCountTable("aabbccddrr")

Source Edit

iterator mpairs[A](t: var CountTable[A]): (A, var int)

Iterates over any (key, value) pair in the table t (must be declared as var). The values can be modified.

See also:

• pairs iterator
• mvalues iterator

Example:

var a = toCountTable("abracadabra")
for k, v in mpairs(a):
  v = 2
doAssert a == toCountTable("aabbccddrr")

Source Edit

iterator mvalues[A, B](t: OrderedTableRef[A, B]): var B

Iterates over any value in the table t in insertion order. The values can be modified.

See also:

• mpairs iterator
• values iterator

Example:

let a = {
  'o': @[1, 5, 7, 9],
  'e': @[2, 4, 6, 8]
  }.newOrderedTable
for v in a.mvalues:
  v.add(99)
doAssert a == {'o': @[1, 5, 7, 9, 99],
               'e': @[2, 4, 6, 8, 99]}.newOrderedTable

Source Edit

iterator mvalues[A, B](t: TableRef[A, B]): var B

Iterates over any value in the table t. The values can be modified.

See also:

• mpairs iterator
• values iterator

Example:

let a = {
  'o': @[1, 5, 7, 9],
  'e': @[2, 4, 6, 8]
  }.newTable
for v in a.mvalues:
  v.add(99)
doAssert a == {'e': @[2, 4, 6, 8, 99], 'o': @[1, 5, 7, 9, 99]}.newTable

Source Edit

iterator mvalues[A, B](t: var OrderedTable[A, B]): var B

Iterates over any value in the table t (must be declared as var) in insertion order. The values can be modified.

See also:

• mpairs iterator
• values iterator

Example:

var a = {
  'o': @[1, 5, 7, 9],
  'e': @[2, 4, 6, 8]
  }.toOrderedTable
for v in a.mvalues:
  v.add(99)
doAssert a == {'o': @[1, 5, 7, 9, 99],
               'e': @[2, 4, 6, 8, 99]}.toOrderedTable

Source Edit

iterator mvalues[A, B](t: var Table[A, B]): var B

Iterates over any value in the table t (must be declared as var). The values can be modified.

See also:

• mpairs iterator
• values iterator

Example:

var a = {
  'o': @[1, 5, 7, 9],
  'e': @[2, 4, 6, 8]
  }.toTable
for v in a.mvalues:
  v.add(99)
doAssert a == {'e': @[2, 4, 6, 8, 99], 'o': @[1, 5, 7, 9, 99]}.toTable

Source Edit

iterator mvalues[A](t: CountTableRef[A]): var int

Iterates over any value in the table t. The values can be modified.

See also:

• mpairs iterator
• values iterator

Example:

var a = newCountTable("abracadabra")
for v in mvalues(a):
  v = 2
doAssert a == newCountTable("aabbccddrr")

Source Edit

iterator mvalues[A](t: var CountTable[A]): var int

Iterates over any value in the table t (must be declared as var). The values can be modified.

See also:

• mpairs iterator
• values iterator

Example:

var a = toCountTable("abracadabra")
for v in mvalues(a):
  v = 2
doAssert a == toCountTable("aabbccddrr")

Source Edit

iterator pairs[A, B](t: OrderedTable[A, B]): (A, B)

Iterates over any (key, value) pair in the table t in insertion order.

See also:

• mpairs iterator
• keys iterator
• values iterator

Examples:

let a = {
  'o': [1, 5, 7, 9],
  'e': [2, 4, 6, 8]
  }.toOrderedTable

for k, v in a.pairs:
  echo "key: ", k
  echo "value: ", v

# key: o
# value: [1, 5, 7, 9]
# key: e
# value: [2, 4, 6, 8]

Source Edit

iterator pairs[A, B](t: OrderedTableRef[A, B]): (A, B)

Iterates over any (key, value) pair in the table t in insertion order.

See also:

• mpairs iterator
• keys iterator
• values iterator

Examples:

let a = {
  'o': [1, 5, 7, 9],
  'e': [2, 4, 6, 8]
  }.newOrderedTable

for k, v in a.pairs:
  echo "key: ", k
  echo "value: ", v

# key: o
# value: [1, 5, 7, 9]
# key: e
# value: [2, 4, 6, 8]

Source Edit

iterator pairs[A, B](t: Table[A, B]): (A, B)

Iterates over any (key, value) pair in the table t.

See also:

• mpairs iterator
• keys iterator
• values iterator

Examples:

let a = {
  'o': [1, 5, 7, 9],
  'e': [2, 4, 6, 8]
  }.toTable

for k, v in a.pairs:
  echo "key: ", k
  echo "value: ", v

# key: e
# value: [2, 4, 6, 8]
# key: o
# value: [1, 5, 7, 9]

Source Edit

iterator pairs[A, B](t: TableRef[A, B]): (A, B)

Iterates over any (key, value) pair in the table t.

See also:

• mpairs iterator
• keys iterator
• values iterator

Examples:

let a = {
  'o': [1, 5, 7, 9],
  'e': [2, 4, 6, 8]
  }.newTable

for k, v in a.pairs:
  echo "key: ", k
  echo "value: ", v

# key: e
# value: [2, 4, 6, 8]
# key: o
# value: [1, 5, 7, 9]

Source Edit

iterator pairs[A](t: CountTable[A]): (A, int)

Iterates over any (key, value) pair in the table t.

See also:

• mpairs iterator
• keys iterator
• values iterator

Examples:

let a = toCountTable("abracadabra")

for k, v in pairs(a):
  echo "key: ", k
  echo "value: ", v

# key: a
# value: 5
# key: b
# value: 2
# key: c
# value: 1
# key: d
# value: 1
# key: r
# value: 2

Source Edit

iterator pairs[A](t: CountTableRef[A]): (A, int)

Iterates over any (key, value) pair in the table t.

See also:

• mpairs iterator
• keys iterator
• values iterator

Examples:

let a = newCountTable("abracadabra")

for k, v in pairs(a):
  echo "key: ", k
  echo "value: ", v

# key: a
# value: 5
# key: b
# value: 2
# key: c
# value: 1
# key: d
# value: 1
# key: r
# value: 2

Source Edit

iterator values[A, B](t: OrderedTable[A, B]): lent B

Iterates over any value in the table t in insertion order.

See also:

• pairs iterator
• keys iterator
• mvalues iterator

Example:

let a = {
  'o': @[1, 5, 7, 9],
  'e': @[2, 4, 6, 8]
  }.toOrderedTable
for v in a.values:
  doAssert v.len == 4

Source Edit

iterator values[A, B](t: OrderedTableRef[A, B]): lent B

Iterates over any value in the table t in insertion order.

See also:

• pairs iterator
• keys iterator
• mvalues iterator

Example:

let a = {
  'o': @[1, 5, 7, 9],
  'e': @[2, 4, 6, 8]
  }.newOrderedTable
for v in a.values:
  doAssert v.len == 4

Source Edit

iterator values[A, B](t: Table[A, B]): lent B

Iterates over any value in the table t.

See also:

• pairs iterator
• keys iterator
• mvalues iterator

Example:

let a = {
  'o': @[1, 5, 7, 9],
  'e': @[2, 4, 6, 8]
  }.toTable
for v in a.values:
  doAssert v.len == 4

Source Edit

iterator values[A, B](t: TableRef[A, B]): lent B

Iterates over any value in the table t.

See also:

• pairs iterator
• keys iterator
• mvalues iterator

Example:

let a = {
  'o': @[1, 5, 7, 9],
  'e': @[2, 4, 6, 8]
  }.newTable
for v in a.values:
  doAssert v.len == 4

Source Edit

iterator values[A](t: CountTable[A]): int

Iterates over any value in the table t.

See also:

• pairs iterator
• keys iterator
• mvalues iterator

Example:

let a = toCountTable("abracadabra")
for v in values(a):
  assert v < 10

Source Edit

iterator values[A](t: CountTableRef[A]): int

Iterates over any value in the table t.

See also:

• pairs iterator
• keys iterator
• mvalues iterator

Example:

let a = newCountTable("abracadabra")
for v in values(a):
  assert v < 10

Source Edit

Templates

template withValue[A, B](t: var Table[A, B]; key: A;
                         value, body1, body2: untyped)

Retrieves the value at t[key].

value can be modified in the scope of the withValue call.

Example:

type
  User = object
    name: string
    uid: int

var t = initTable[int, User]()
let u = User(name: "Hello", uid: 99)
t[1] = u

t.withValue(1, value):
  # block is executed only if `key` in `t`
  value.name = "Nim"
  value.uid = 1314

t.withValue(521, value):
  doAssert false
do:
  # block is executed when `key` not in `t`
  t[1314] = User(name: "exist", uid: 521)

assert t[1].name == "Nim"
assert t[1].uid == 1314
assert t[1314].name == "exist"
assert t[1314].uid == 521

Source Edit

template withValue[A, B](t: var Table[A, B]; key: A; value, body: untyped)

Retrieves the value at t[key].

value can be modified in the scope of the withValue call.

Example:

type
  User = object
    name: string
    uid: int

var t = initTable[int, User]()
let u = User(name: "Hello", uid: 99)
t[1] = u

t.withValue(1, value):
  # block is executed only if `key` in `t`
  value.name = "Nim"
  value.uid = 1314

t.withValue(2, value):
  value.name = "No"
  value.uid = 521

assert t[1].name == "Nim"
assert t[1].uid == 1314

Source Edit