# tables

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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:

    import tables

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

    echo a, b  # output: {1: one, 2: two}{1: one, 2: two}

    b[3] = "three"
    echo a, b  # output: {1: one, 2: two}{1: one, 2: two, 3: three}
    echo a == b  # output: false

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:

    import tables

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

    echo a, b  # output: {1: one, 2: two}{1: one, 2: two}

    b[3] = "three"
    echo a, b  # output: {1: one, 2: two, 3: three}{1: one, 2: two, 3: three}
    echo a == b  # output: true

# Basic usage

## Table

    import tables
    from 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

    echo beatles
    # {"George": 1943, "Ringo": 1940, "Paul": 1942, "John": 1940}

    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)

    echo beatlesByYear
    # {1940: @["John", "Ringo"], 1942: @["Paul"], 1943: @["George"]}

## OrderedTable

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

    import tables

    let
      a = [('z', 1), ('y', 2), ('x', 3)]
      t = a.toTable          # regular table
      ot = a.toOrderedTable  # ordered tables

    echo t   # {'x': 3, 'y': 2, 'z': 1}
    echo 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:

    import tables

    let myString = "abracadabra"
    let letterFrequencies = toCountTable(myString)
    echo letterFrequencies
    # 'a': 5, 'b': 2, 'c': 1, 'd': 1, 'r': 2}

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

    import tables

    let myString = "abracadabra"
    var letterFrequencies = initCountTable[char]()
    for c in myString:
      letterFrequencies.inc(c)
    echo letterFrequencies
    # output: {'a': 5, 'b': 2, 'c': 1, 'd': 1, 'r': 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:

    import tables, 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
- sharedtables module for shared hash table support
- strtabs module for efficient hash tables mapping from strings to strings
- hashes module for helper functions for hashing

# Imports

hashes, math, algorithm

# Types

    Table[A; B] = object
      data: KeyValuePairSeq[A, B]
      counter: int

  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

    OrderedTable[A; B] = object
      data: OrderedKeyValuePairSeq[A, B]
      counter, first, last: int

  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

    CountTable[A] = object
      data: seq[tuple[key: A, val: int]]
      counter: int
      isSorted: bool

  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

# Consts

    defaultInitialSize = 64

  Source Edit

# Procs

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

  Creates a new hash table that is empty.

  `initialSize` must be a power of two (default: 64). If you need to accept runtime values for this you could use the nextPowerOfTwo proc from the math module or the rightSize proc from this module.

  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`

  Examples:

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

  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

  Examples:

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

  Source Edit

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

  Examples:

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

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

  Examples:

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

  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

  Examples:

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

  Examples:

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

  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

  Examples:

      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 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

  Examples:

      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

  Examples:

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

  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.

  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

  Examples:

      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

  Source Edit

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

  Returns the number of keys in `t`.

  Examples:

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

  Source Edit

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

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

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

  See also:

  - take proc
  - clear proc to empty the whole table

  Examples:

      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 take[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.

  See also:

  - del proc
  - clear proc to empty the whole table

  Examples:

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

  Source Edit

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

  Resets the table so that it is empty.

  See also:

  - del proc
  - take proc

  Examples:

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

  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](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.

  Examples:

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

  Source Edit

    proc rightSize(count: Natural): int {...}{.inline, raises: [], tags: [].}

  Return the value of `initialSize` to support `count` items.

  If more items are expected to be added, simply add that expected extra amount to the parameter before calling this.

  Internally, we want mustRehash(rightSize(x), x) == false.

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

  Creates a new ref hash table that is empty.

  `initialSize` must be a power of two (default: 64). If you need to accept runtime values for this you could use the nextPowerOfTwo proc from the math module or the rightSize proc from this module.

  See also:

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

  Examples:

      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

  Examples:

      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 `[]`[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

  Examples:

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

  Source Edit

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

  Examples:

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

  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

  Examples:

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

  Examples:

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

  Source Edit

    proc hasKeyOrPut[A, B](t: var 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

  Examples:

      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 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

  Examples:

      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

  Examples:

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

  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.

  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

  Examples:

      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

  Source Edit

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

  Returns the number of keys in `t`.

  Examples:

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

  Source Edit

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

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

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

  If duplicate keys were added, this may need to be called multiple times.

  See also:

  - take proc
  - clear proc to empty the whole table

  Examples:

      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 take[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.

  If duplicate keys were added, this may need to be called multiple times.

  See also:

  - del proc
  - clear proc to empty the whole table

  Examples:

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

  Source Edit

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

  Resets the table so that it is empty.

  See also:

  - del proc
  - take proc

  Examples:

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

  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, 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.

  Examples:

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

  Source Edit

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

  Creates a new ordered hash table that is empty.

  `initialSize` must be a power of two (default: 64). If you need to accept runtime values for this you could use the nextPowerOfTwo proc from the math module or the rightSize proc from this module.

  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`

  Examples:

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

  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

  Examples:

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

  Source Edit

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

  Examples:

      let a = {'a': 5, 'b': 9}.toOrderedTable
      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 OrderedTable[A, B]; key: A; val: 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

  Examples:

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

  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

  Examples:

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

  Source Edit

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

  Alias of hasKey proc for use with the `in` operator.

  Examples:

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

  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

  Examples:

      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 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

  Examples:

      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

  Examples:

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

  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

  Examples:

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

  Returns the number of keys in `t`.

  Examples:

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

  Source Edit

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

  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 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:

  - clear proc to empty the whole table

  Examples:

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

  Resets the table so that it is empty.

  See also:

  - del proc

  Examples:

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

  Source Edit

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

  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).

  Examples:

      import
        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 `$`[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](s, t: OrderedTable[A, B]): bool

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

  Examples:

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

  Source Edit

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

  Creates a new ordered ref hash table that is empty.

  `initialSize` must be a power of two (default: 64). If you need to accept runtime values for this you could use the nextPowerOfTwo proc from the math module or the rightSize proc from this module.

  See also:

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

  Examples:

      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

  Examples:

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

  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

  Examples:

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

  Source Edit

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

  Examples:

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

  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

  Examples:

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

  Examples:

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

  Source Edit

    proc hasKeyOrPut[A, B](t: var 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

  Examples:

      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 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

  Examples:

      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

  Examples:

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

  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

  Examples:

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

  Returns the number of keys in `t`.

  Examples:

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

  Source Edit

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

  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 del[A, B](t: var 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

  Examples:

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

  Resets the table so that it is empty.

  See also:

  - del proc

  Examples:

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

  Source Edit

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

  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).

  Examples:

      import
        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 `$`[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](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.

  Examples:

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

  Source Edit

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

  Creates a new count table that is empty.

  `initialSize` must be a power of two (default: 64). If you need to accept runtime values for this you could use the nextPowerOfTwo proc from the math module or the rightSize proc from this module.

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

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

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

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

  Increments `t[key]` by `val` (default: 1).

  Examples:

      var a = toCountTable("aab")
      a.inc('a')
      a.inc('b', 10)
      doAssert a == toCountTable("aaabbbbbbbbbbb")

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

  Alias of hasKey proc for use with the `in` operator. 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 len[A](t: CountTable[A]): int

  Returns the number of keys in `t`. Source Edit

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

  Resets the table so that it is empty. 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.

  Examples:

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

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

  Examples:

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

  Source Edit

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

  Merges the two tables into a new one.

  Examples:

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

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

  Creates a new ref count table that is empty.

  `initialSize` must be a power of two (default: 64). If you need to accept runtime values for this you could use the nextPowerOfTwo proc from the math module or the rightSize proc from this module.

  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 `[]`[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
  - mget proc
  - []= 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 mget[A](t: CountTableRef[A]; key: A): var int

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

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

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

  Increments `t[key]` by `val` (default: 1).

  Examples:

      var a = newCountTable("aab")
      a.inc('a')
      a.inc('b', 10)
      doAssert a == newCountTable("aaabbbbbbbbbbb")

  Source Edit

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

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

  See also:

  - largest proc
  Source Edit

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

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

  See also:

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

  Alias of hasKey proc for use with the `in` operator. 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 len[A](t: CountTableRef[A]): int

  Returns the number of keys in `t`. Source Edit

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

  Resets the table so that it is empty. 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 merge[A](s, t: CountTableRef[A])

  Merges the second table into the first one.

  Examples:

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

  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](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

# Iterators

    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 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

  Examples:

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

  Iterates over any key in the table `t`.

  See also:

  - pairs iterator
  - values iterator

  Examples:

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

  Iterates over any value in the table `t`.

  See also:

  - pairs iterator
  - keys iterator
  - mvalues iterator

  Examples:

      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 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

  Examples:

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

  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).

  Examples:

      var a = {'a': 3, 'b': 5}.toTable
      for i in 1..3:
        a.add('z', 10*i)
      echo a # {'a': 3, 'b': 5, 'z': 10, 'z': 20, 'z': 30}

      for v in a.allValues('z'):
        echo v
      # 10
      # 20
      # 30

  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 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

  Examples:

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

  Iterates over any key in the table `t`.

  See also:

  - pairs iterator
  - values iterator

  Examples:

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

  Iterates over any value in the table `t`.

  See also:

  - pairs iterator
  - keys iterator
  - mvalues iterator

  Examples:

      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 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

  Examples:

      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 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 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

  Examples:

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

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

  See also:

  - pairs iterator
  - values iterator

  Examples:

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

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

  See also:

  - pairs iterator
  - keys iterator
  - mvalues iterator

  Examples:

      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 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

  Examples:

      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 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 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

  Examples:

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

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

  See also:

  - pairs iterator
  - values iterator

  Examples:

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

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

  See also:

  - pairs iterator
  - keys iterator
  - mvalues iterator

  Examples:

      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 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

  Examples:

      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 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 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

  Examples:

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

  Source Edit

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

  Iterates over any key in the table `t`.

  See also:

  - pairs iterator
  - values iterator

  Examples:

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

  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

  Examples:

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

  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

  Examples:

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

  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 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

  Examples:

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

  Source Edit

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

  Iterates over any key in the table `t`.

  See also:

  - pairs iterator
  - values iterator

  Examples:

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

  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

  Examples:

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

  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

  Examples:

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

  Source Edit

# Templates

    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.

      sharedTable.withValue(key, value) do:
        # block is executed only if ``key`` in ``t``
        value.name = "username"
        value.uid = 1000

  Source Edit

    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.

      table.withValue(key, value) do:
        # block is executed only if ``key`` in ``t``
        value.name = "username"
        value.uid = 1000
      do:
        # block is executed when ``key`` not in ``t``
        raise newException(KeyError, "Key not found")

  Source Edit