A.OrdMap (Aja v0.4.3) View Source

A Map preserving key insertion order, with efficient lookups and updates.

Works just like regular maps, except that the insertion order is preserved:

iex> %{"one" => 1, "two" => 2, "three" => 3}
%{"one" => 1, "three" => 3, "two" => 2}
iex> A.OrdMap.new([{"one", 1}, {"two", 2}, {"three", 3}])
#A<ord(%{"one" => 1, "two" => 2, "three" => 3})>

There is an unavoidable overhead compared to natively implemented maps, so keep using regular maps when you do not care about the insertion order.

A.OrdMap:

Examples

A.OrdMap offers the same API as Map :

iex> ord_map = A.OrdMap.new([b: "Bat", a: "Ant", c: "Cat"])
#A<ord(%{b: "Bat", a: "Ant", c: "Cat"})>
iex> A.OrdMap.get(ord_map, :c)
"Cat"
iex> A.OrdMap.fetch(ord_map, :a)
{:ok, "Ant"}
iex> A.OrdMap.put(ord_map, :d, "Dinosaur")
#A<ord(%{b: "Bat", a: "Ant", c: "Cat", d: "Dinosaur"})>
iex> A.OrdMap.put(ord_map, :b, "Buffalo")
#A<ord(%{b: "Buffalo", a: "Ant", c: "Cat"})>
iex> A.OrdMap.delete(ord_map, :b)
#A<ord(%{a: "Ant", c: "Cat"})>
iex> Enum.to_list(ord_map)
[b: "Bat", a: "Ant", c: "Cat"]
iex> [d: "Dinosaur", b: "Buffalo", e: "Eel"] |> Enum.into(ord_map)
#A<ord(%{b: "Buffalo", a: "Ant", c: "Cat", d: "Dinosaur", e: "Eel"})>

Tree-specific functions

Due to its sorted nature, A.OrdMap also offers some extra methods not present in Map, like:

Examples:

iex> ord_map = A.OrdMap.new(b: "Bat", a: "Ant", c: "Cat")
iex> A.OrdMap.first(ord_map)
{:b, "Bat"}
iex> {:c, "Cat", updated} = A.OrdMap.pop_last(ord_map)
iex> updated
#A<ord(%{b: "Bat", a: "Ant"})>
iex> A.OrdMap.foldr(ord_map, [], fn _key, value, acc -> [value <> "man" | acc] end)
["Batman", "Antman", "Catman"]

Access behaviour

A.OrdMap implements the Access behaviour.

iex> ord_map = A.OrdMap.new([a: "Ant", b: "Bat", c: "Cat"])
iex> ord_map[:a]
"Ant"
iex> put_in(ord_map[:b], "Buffalo")
#A<ord(%{a: "Ant", b: "Buffalo", c: "Cat"})>
iex> put_in(ord_map[:d], "Dinosaur")
#A<ord(%{a: "Ant", b: "Bat", c: "Cat", d: "Dinosaur"})>
iex> {"Cat", updated} = pop_in(ord_map[:c]); updated
#A<ord(%{a: "Ant", b: "Bat"})>

Convenience ord/1 macro

The A.OrdMap module can be used without any macro. The A.ord/1 macro does however provide some syntactic sugar to make it more convenient to work with ordered maps, namely:

  • construct new ordered maps without the clutter of a entry list
  • pattern match on key-values like regular maps
  • update some existing keys

Examples:

iex> import A
iex> ord_map = ord(%{"一" => 1, "二" => 2, "三" => 3})
#A<ord(%{"一" => 1, "二" => 2, "三" => 3})>
iex> ord(%{"三" => three, "一" => one}) = ord_map
iex> {one, three}
{1, 3}
iex> ord(%{ord_map | "二" => "NI!"})
#A<ord(%{"一" => 1, "二" => "NI!", "三" => 3})>

Note: pattern-matching on keys doesn't care about the insertion order.

With Jason

iex> A.OrdMap.new([{"un", 1}, {"deux", 2}, {"trois", 3}]) |> Jason.encode!()
"{\"un\":1,\"deux\":2,\"trois\":3}"

It also preserves the insertion order. Comparing with a regular map:

iex> Map.new([{"un", 1}, {"deux", 2}, {"trois", 3}]) |> Jason.encode!()
"{\"deux\":2,\"trois\":3,\"un\":1}"

There is no way as of now to decode JSON using A.OrdMap.

Limitations: equality

A.OrdMap comparisons based on ==/2, ===/2 or the pin operator ^ are UNRELIABLE.

In Elixir, pattern-matching and equality for structs work based on their internal representation. While this is a pragmatic design choice that simplifies the language, it means that we cannot rededine how they work for custom data structures.

Two ordered maps that are semantically equal (same key-value pairs in the same order) might be considered non-equal when comparing their internals, because there is not a unique way of representing one same map.

A.OrdMap.equal?/2 should be used instead:

iex> ord_map1 = A.OrdMap.new(a: "Ant", b: "Bat")
#A<ord(%{a: "Ant", b: "Bat"})>
iex> ord_map2 = A.OrdMap.new(c: "Cat", a: "Ant", b: "Bat") |> A.OrdMap.delete(:c)
#A<ord(%{a: "Ant", b: "Bat"})>
iex> ord_map1 == ord_map2
false
iex> A.OrdMap.equal?(ord_map1, ord_map2)
true
iex> match?(^ord_map1, ord_map2)
false

Pattern-matching and opaque type

An A.OrdMap is represented internally using the %A.OrdMap{} struct. This struct can be used whenever there's a need to pattern match on something being an A.OrdMap:

iex> match?(%A.OrdMap{}, A.OrdMap.new())
true

Note, however, than A.OrdMap is an opaque type: its struct internal fields must not be accessed directly.

As discussed in the previous section, ord/1 makes it possible to pattern match on keys as well as checking the type.

Memory overhead

A.OrdMap takes roughly more memory 2.5~3x than a regular map depending on the type of data:

iex> map_size = 1..100 |> Map.new(fn i -> {i, <<i>>} end) |> :erts_debug.size()
658
iex> ord_map_size = 1..100 |> A.OrdMap.new(fn i -> {i, <<i>>} end) |> :erts_debug.size()
1668
iex> div(100 * ord_map_size, map_size)
253

Difference with A.RBMap

  • A.OrdMap keeps track of key insertion order
  • A.RBMap keeps keys sorted in ascending order whatever the insertion order is

Link to this section Summary

Functions

Deletes the entry in ord_map for a specific key.

Drops the given keys from ord_map.

Checks if two ordered maps are equal, meaning they have the same key-value pairs in the same order.

Fetches the value for a specific key and returns it in a ok-entry. If the key does not exist, returns :error.

Fetches the value for a specific key in the given ord_map, erroring out if ord_map doesn't contain key.

Finds the fist {key, value} pair in ord_map.

Folds (reduces) the given ord_map from the left with the function fun. Requires an accumulator acc.

Folds (reduces) the given ord_map from the right with the function fun. Requires an accumulator acc.

Converts a struct to an ordered map.

Gets the value for a specific key in ord_map.

Gets the value from key and updates it, all in one pass.

Gets the value from key and updates it, all in one pass.

Gets the value for a specific key in ord_map.

Returns whether the given key exists in ord_map.

Returns all keys from ord_map.

Finds the last {key, value} pair in ord_map.

Merges two ordered maps into one.

Returns a new empty ordered map.

Creates an ordered map from an enumerable.

Creates an ordered map from an enumerable via the given transform function.

Returns the value for key and the updated ordered map without key.

Returns the value for key and the updated ordered map without key.

Finds and pops the first {key, value} pair in ord_map.

Finds and pops the last {key, value} pair in ord_map.

Lazily returns and removes the value associated with key in ord_map.

Puts the given value under key in ord_map.

Puts the given value under key unless the entry key already exists in ord_map.

Evaluates fun and puts the result under key in ord_map unless key is already present.

Puts a value under key only if the key already exists in ord_map.

Puts a value under key only if the key already exists in ord_map.

Returns the number of keys in ord_map.

Returns a new ordered map with all the key-value pairs in ord_map where the key is in keys.

Returns all values from ord_map.

Puts a value under key only if the key already exists in ord_map.

Puts a value under key only if the key already exists in ord_map.

Returns all values from ord_map.

Link to this section Types

Specs

key() :: term()

Specs

t()

Specs

t(key, value)

Specs

value() :: term()

Link to this section Functions

Specs

delete(t(k, v), k) :: t(k, v) when k: key(), v: value()

Deletes the entry in ord_map for a specific key.

If the key does not exist, returns ord_map unchanged.

Examples

iex> ord_map = A.OrdMap.new(a: "Ant", b: "Bat", c: "Cat")
iex> A.OrdMap.delete(ord_map, :b)
#A<ord(%{a: "Ant", c: "Cat"})>
iex> A.OrdMap.delete(ord_map, :z)
#A<ord(%{a: "Ant", b: "Bat", c: "Cat"})>

Specs

drop(t(k, v), [k]) :: t(k, v) when k: key(), v: value()

Drops the given keys from ord_map.

If keys contains keys that are not in ord_map, they're simply ignored.

Examples

iex> ord_map = A.OrdMap.new(a: "Ant", b: "Bat", c: "Cat")
iex> A.OrdMap.drop(ord_map, [:b, :d])
#A<ord(%{a: "Ant", c: "Cat"})>
Link to this function

equal?(ord_map1, ord_map2)

View Source

Specs

equal?(t(), t()) :: boolean()

Checks if two ordered maps are equal, meaning they have the same key-value pairs in the same order.

Examples

iex> A.OrdMap.equal?(A.OrdMap.new(a: 1, b: 2), A.OrdMap.new(a: 1, b: 2))
true
iex> A.OrdMap.equal?(A.OrdMap.new(a: 1, b: 2), A.OrdMap.new(b: 2, a: 1))
false
iex> A.OrdMap.equal?(A.OrdMap.new(a: 1, b: 2), A.OrdMap.new(a: 3, b: 2))
false

Specs

fetch(t(k, v), k) :: {:ok, v} | :error when k: key(), v: value()

Fetches the value for a specific key and returns it in a ok-entry. If the key does not exist, returns :error.

Examples

iex> ord_map = A.OrdMap.new(a: "A", b: "B", c: "C")
iex> A.OrdMap.fetch(ord_map, :c)
{:ok, "C"}
iex> A.OrdMap.fetch(ord_map, :z)
:error

Specs

fetch!(t(k, v), k) :: v when k: key(), v: value()

Fetches the value for a specific key in the given ord_map, erroring out if ord_map doesn't contain key.

If ord_map doesn't contain key, a KeyError exception is raised.

Examples

iex> ord_map = A.OrdMap.new(a: "A", b: "B", c: "C")
iex> A.OrdMap.fetch!(ord_map, :c)
"C"
iex> A.OrdMap.fetch!(ord_map, :z)
** (KeyError) key :z not found in: #A<ord(%{a: "A", b: "B", c: "C"})>
Link to this function

first(ord_map, default \\ nil)

View Source

Specs

first(t(k, v), default) :: {k, v} | default
when k: key(), v: value(), default: term()

Finds the fist {key, value} pair in ord_map.

Returns a {key, value} entry if ord_map is non-empty, or nil else.

Examples

iex> A.OrdMap.new([b: "B", d: "D", a: "A", c: "C"]) |> A.OrdMap.first()
{:b, "B"}
iex> A.OrdMap.new([]) |> A.OrdMap.first()
nil
iex> A.OrdMap.new([]) |> A.OrdMap.first(:error)
:error
Link to this function

foldl(ord_map, acc, fun)

View Source

Folds (reduces) the given ord_map from the left with the function fun. Requires an accumulator acc.

Examples

iex> ord_map = A.OrdMap.new([b: "Bat", c: "Cat", a: "Ant"])
iex> A.OrdMap.foldl(ord_map, "", fn _key, value, acc -> value <> acc end)
"AntCatBat"
iex> A.OrdMap.foldl(ord_map, [], fn key, value, acc -> [{key, value <> "man"} | acc] end)
[a: "Antman", c: "Catman", b: "Batman"]
Link to this function

foldr(ord_map, acc, fun)

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Folds (reduces) the given ord_map from the right with the function fun. Requires an accumulator acc.

Unlike linked lists, this is as efficient as foldl/3. This can typically save a call to Enum.reverse/1 on the result when building a list.

Examples

iex> ord_map = A.OrdMap.new([b: "Bat", c: "Cat", a: "Ant"])
iex> A.OrdMap.foldr(ord_map, "", fn _key, value, acc -> value <> acc end)
"BatCatAnt"
iex> A.OrdMap.foldr(ord_map, [], fn key, value, acc -> [{key, value <> "man"} | acc] end)
[b: "Batman", c: "Catman", a: "Antman"]

Specs

from_struct(atom() | struct()) :: t()

Converts a struct to an ordered map.

It accepts the struct module or a struct itself and simply removes the __struct__ field from the given struct or from a new struct generated from the given module.

Example

defmodule User do
  defstruct [:name, :age]
end

A.OrdMap.from_struct(User)
#A<ord(%{age: nil, name: nil})>

A.OrdMap.from_struct(%User{name: "john", age: 44})
#A<ord(%{age: 44, name: "john"})>
Link to this function

get(ord_map, key, default \\ nil)

View Source

Specs

get(t(k, v), k, v) :: v | nil when k: key(), v: value()

Gets the value for a specific key in ord_map.

If key is present in ord_map then its value value is returned. Otherwise, default is returned.

If default is not provided, nil is used.

Examples

iex> ord_map = A.OrdMap.new(a: "Ant", b: "Bat", c: "Cat")
iex> A.OrdMap.get(ord_map, :a)
"Ant"
iex> A.OrdMap.get(ord_map, :z)
nil
iex> A.OrdMap.get(ord_map, :z, "Zebra")
"Zebra"
Link to this function

get_and_update(ord_map, key, fun)

View Source

Specs

get_and_update(t(k, v), k, (v -> {returned, v} | :pop)) :: {returned, t(k, v)}
when k: key(), v: value(), returned: term()

Gets the value from key and updates it, all in one pass.

Mirrors Map.get_and_update/3, see its documentation.

Examples

iex> ord_map = A.OrdMap.new(a: "Ant", b: "Bat", c: "Cat")
iex> {"bat", updated} = A.OrdMap.get_and_update(ord_map, :b, fn current_value ->
...>   {current_value && String.downcase(current_value), "Buffalo"}
...> end)
iex> updated
#A<ord(%{a: "Ant", b: "Buffalo", c: "Cat"})>
iex> {nil, updated} = A.OrdMap.get_and_update(ord_map, :z, fn current_value ->
...>   {current_value && String.downcase(current_value), "Zebra"}
...> end)
iex> updated
#A<ord(%{a: "Ant", b: "Bat", c: "Cat", z: "Zebra"})>
iex> {"Bat", updated} = A.OrdMap.get_and_update(ord_map, :b, fn _ -> :pop end)
iex> updated
#A<ord(%{a: "Ant", c: "Cat"})>
iex> {nil, updated} = A.OrdMap.get_and_update(ord_map, :z, fn _ -> :pop end)
iex> updated
#A<ord(%{a: "Ant", b: "Bat", c: "Cat"})>
Link to this function

get_and_update!(ord_map, key, fun)

View Source

Specs

get_and_update!(t(k, v), k, (v -> {returned, v} | :pop)) :: {returned, t(k, v)}
when k: key(), v: value(), returned: term()

Gets the value from key and updates it, all in one pass.

Mirrors Map.get_and_update!/3, see its documentation.

Examples

iex> ord_map = A.OrdMap.new(a: "Ant", b: "Bat", c: "Cat")
iex> {"bat", updated} = A.OrdMap.get_and_update!(ord_map, :b, fn current_value ->
...>   {current_value && String.downcase(current_value), "Buffalo"}
...> end)
iex> updated
#A<ord(%{a: "Ant", b: "Buffalo", c: "Cat"})>
iex> A.OrdMap.get_and_update!(ord_map, :z, fn current_value ->
...>   {current_value && String.downcase(current_value), "Zebra"}
...> end)
** (KeyError) key :z not found in: #A<ord(%{a: "Ant", b: "Bat", c: "Cat"})>
Link to this function

get_lazy(ord_map, key, fun)

View Source

Specs

get_lazy(t(k, v), k, v) :: v | nil when k: key(), v: value()

Gets the value for a specific key in ord_map.

If key is present in ord_map then its value value is returned. Otherwise, fun is evaluated and its result is returned.

This is useful if the default value is very expensive to calculate or generally difficult to setup and teardown again.

Examples

iex> ord_map = A.OrdMap.new(a: "Ant", b: "Bat", c: "Cat")
iex> expensive_fun = fn -> "Zebra" end
iex> A.OrdMap.get_lazy(ord_map, :a, expensive_fun)
"Ant"
iex> A.OrdMap.get_lazy(ord_map, :z, expensive_fun)
"Zebra"

Specs

has_key?(t(k, value()), k) :: boolean() when k: key()

Returns whether the given key exists in ord_map.

Examples

iex> ord_map = A.OrdMap.new(a: "Ant", b: "Bat", c: "Cat")
iex> A.OrdMap.has_key?(ord_map, :a)
true
iex> A.OrdMap.has_key?(ord_map, :d)
false

Specs

keys(t(k, value())) :: [k] when k: key()

Returns all keys from ord_map.

Examples

iex> ord_map = A.OrdMap.new(b: "Bat", c: "Cat", a: "Ant")
iex> A.OrdMap.keys(ord_map)
[:b, :c, :a]
Link to this function

last(ord_map, default \\ nil)

View Source

Specs

last(t(k, v), default) :: {k, v} | default
when k: key(), v: value(), default: term()

Finds the last {key, value} pair in ord_map.

Returns a {key, value} entry if ord_map is non-empty, or nil else. Can be accessed efficiently due to the underlying tree.

Examples

iex> A.OrdMap.new([b: "B", d: "D", a: "A", c: "C"]) |> A.OrdMap.last()
{:c, "C"}
iex> A.OrdMap.new([]) |> A.OrdMap.last()
nil
iex> A.OrdMap.new([]) |> A.OrdMap.last(:error)
:error
Link to this function

merge(ord_map1, ord_map2)

View Source

Specs

merge(t(k, v), t(k, v)) :: t(k, v) when k: key(), v: value()

Merges two ordered maps into one.

All keys in ord_map2 will be added to ord_map1, overriding any existing one (i.e., the keys in ord_map2 "have precedence" over the ones in ord_map1).

Examples

iex> A.OrdMap.merge(A.OrdMap.new(%{a: 1, b: 2}), A.OrdMap.new(%{a: 3, d: 4}))
#A<ord(%{a: 3, b: 2, d: 4})>

Specs

new() :: t()

Returns a new empty ordered map.

Examples

iex> A.OrdMap.new()
#A<ord(%{})>

Specs

new(Enumerable.t()) :: t(key(), value())

Creates an ordered map from an enumerable.

Preserves the original order of keys. Duplicated keys are removed; the latest one prevails.

Examples

iex> A.OrdMap.new(b: "Bat", a: "Ant", c: "Cat")
#A<ord(%{b: "Bat", a: "Ant", c: "Cat"})>
iex> A.OrdMap.new(b: "Bat", a: "Ant", b: "Buffalo", a: "Antelope")
#A<ord(%{b: "Buffalo", a: "Antelope"})>

Specs

new(Enumerable.t(), (term() -> {k, v})) :: t(k, v) when k: key(), v: value()

Creates an ordered map from an enumerable via the given transform function.

Preserves the original order of keys. Duplicated keys are removed; the latest one prevails.

Examples

iex> A.OrdMap.new([:a, :b], fn x -> {x, x} end)
#A<ord(%{a: :a, b: :b})>
Link to this function

pop(ord_map, key, default \\ nil)

View Source

Specs

pop(t(k, v), k, v) :: {v, t(k, v)} when k: key(), v: value()

Returns the value for key and the updated ordered map without key.

If key is present in the ordered map with a value value, {value, new_ord_map} is returned. If key is not present in the ordered map, {default, ord_map} is returned.

Examples

iex> ord_map = A.OrdMap.new(a: "Ant", b: "Bat", c: "Cat")
iex> {"Bat", updated} = A.OrdMap.pop(ord_map, :b)
iex> updated
#A<ord(%{a: "Ant", c: "Cat"})>
iex> {nil, updated} = A.OrdMap.pop(ord_map, :z)
iex> updated
#A<ord(%{a: "Ant", b: "Bat", c: "Cat"})>
iex> {"Z", updated} = A.OrdMap.pop(ord_map, :z, "Z")
iex> updated
#A<ord(%{a: "Ant", b: "Bat", c: "Cat"})>

Specs

pop!(t(k, v), k) :: {v, t(k, v)} when k: key(), v: value()

Returns the value for key and the updated ordered map without key.

Behaves the same as pop/3 but raises if key is not present in ord_map.

Examples

iex> ord_map = A.OrdMap.new(a: "Ant", b: "Bat", c: "Cat")
iex> {"Bat", updated} = A.OrdMap.pop!(ord_map, :b)
iex> updated
#A<ord(%{a: "Ant", c: "Cat"})>
iex> A.OrdMap.pop!(ord_map, :z)
** (KeyError) key :z not found in: #A<ord(%{a: "Ant", b: "Bat", c: "Cat"})>

Specs

pop_first(t(k, v)) :: {k, v, t(k, v)} | nil when k: key(), v: value()

Finds and pops the first {key, value} pair in ord_map.

Returns a {key, value, new_tree} entry for non-empty maps, nil for empty maps

Examples

iex> ord_map = A.OrdMap.new([b: "B", d: "D", a: "A", c: "C"])
#A<ord(%{b: "B", d: "D", a: "A", c: "C"})>
iex> {:b, "B", updated} = A.OrdMap.pop_first(ord_map)
iex> updated
#A<ord(%{d: "D", a: "A", c: "C"})>
iex> A.OrdMap.new() |> A.OrdMap.pop_first()
nil

Specs

pop_last(t(k, v)) :: {k, v, t(k, v)} | nil when k: key(), v: value()

Finds and pops the last {key, value} pair in ord_map.

Returns a {key, value, new_tree} entry for non-empty maps, nil for empty maps

Examples

iex> ord_map = A.OrdMap.new([b: "B", d: "D", a: "A", c: "C"])
#A<ord(%{b: "B", d: "D", a: "A", c: "C"})>
iex> {:c, "C", updated} = A.OrdMap.pop_last(ord_map)
iex> updated
#A<ord(%{b: "B", d: "D", a: "A"})>
iex> A.OrdMap.new() |> A.OrdMap.pop_last()
nil
Link to this function

pop_lazy(ord_map, key, fun)

View Source

Specs

pop_lazy(t(k, v), k, (() -> v)) :: {v, t(k, v)} when k: key(), v: value()

Lazily returns and removes the value associated with key in ord_map.

If key is present in ord_map, it returns {value, new_map} where value is the value of the key and new_map is the result of removing key from ord_map. If key is not present in ord_map, {fun_result, ord_map} is returned, where fun_result is the result of applying fun.

This is useful if the default value is very expensive to calculate or generally difficult to setup and teardown again.

Examples

iex> ord_map = A.OrdMap.new(b: "Bat", a: "Ant", c: "Cat")
iex> expensive_fun = fn -> "Zebra" end
iex> {"Ant", updated} = A.OrdMap.pop_lazy(ord_map, :a, expensive_fun)
iex> updated
#A<ord(%{b: "Bat", c: "Cat"})>
iex> {"Zebra", not_updated} = A.OrdMap.pop_lazy(ord_map, :z, expensive_fun)
iex> not_updated
#A<ord(%{b: "Bat", a: "Ant", c: "Cat"})>
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put(ord_map, key, value)

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Specs

put(t(k, v), k, v) :: t(k, v) when k: key(), v: value()

Puts the given value under key in ord_map.

If the key does exist, it overwrites the existing value without changing its current location.

Examples

iex> ord_map = A.OrdMap.new(a: "Ant", b: "Bat", c: "Cat")
iex> A.OrdMap.put(ord_map, :b, "Buffalo")
#A<ord(%{a: "Ant", b: "Buffalo", c: "Cat"})>
iex> A.OrdMap.put(ord_map, :d, "Dinosaur")
#A<ord(%{a: "Ant", b: "Bat", c: "Cat", d: "Dinosaur"})>
Link to this function

put_new(ord_map, key, value)

View Source

Specs

put_new(t(k, v), k, v) :: t(k, v) when k: key(), v: value()

Puts the given value under key unless the entry key already exists in ord_map.

Examples

iex> ord_map = A.OrdMap.new(b: "Bat", c: "Cat")
iex> A.OrdMap.put_new(ord_map, :a, "Ant")
#A<ord(%{b: "Bat", c: "Cat", a: "Ant"})>
iex> A.OrdMap.put_new(ord_map, :b, "Buffalo")
#A<ord(%{b: "Bat", c: "Cat"})>
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put_new_lazy(ord_map, key, fun)

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Specs

put_new_lazy(t(k, v), k, (() -> v)) :: t(k, v) when k: key(), v: value()

Evaluates fun and puts the result under key in ord_map unless key is already present.

This function is useful in case you want to compute the value to put under key only if key is not already present, as for example, when the value is expensive to calculate or generally difficult to setup and teardown again.

Examples

iex> ord_map = A.OrdMap.new(b: "Bat", c: "Cat")
iex> expensive_fun = fn -> "Ant" end
iex> A.OrdMap.put_new_lazy(ord_map, :a, expensive_fun)
#A<ord(%{b: "Bat", c: "Cat", a: "Ant"})>
iex> A.OrdMap.put_new_lazy(ord_map, :b, expensive_fun)
#A<ord(%{b: "Bat", c: "Cat"})>
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replace(ord_map, key, value)

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Specs

replace(t(k, v), k, v) :: t(k, v) when k: key(), v: value()

Puts a value under key only if the key already exists in ord_map.

Examples

iex> ord_map = A.OrdMap.new(a: "Ant", b: "Bat", c: "Cat")
iex> A.OrdMap.replace(ord_map, :b, "Buffalo")
#A<ord(%{a: "Ant", b: "Buffalo", c: "Cat"})>
iex> A.OrdMap.replace(ord_map, :d, "Dinosaur")
#A<ord(%{a: "Ant", b: "Bat", c: "Cat"})>
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replace!(ord_map, key, value)

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Specs

replace!(t(k, v), k, v) :: t(k, v) when k: key(), v: value()

Puts a value under key only if the key already exists in ord_map.

If key is not present in ord_map, a KeyError exception is raised.

Examples

iex> ord_map = A.OrdMap.new(a: "Ant", b: "Bat", c: "Cat")
iex> A.OrdMap.replace!(ord_map, :b, "Buffalo")
#A<ord(%{a: "Ant", b: "Buffalo", c: "Cat"})>
iex> A.OrdMap.replace!(ord_map, :d, "Dinosaur")
** (KeyError) key :d not found in: #A<ord(%{a: "Ant", b: "Bat", c: "Cat"})>

Specs

size(t()) :: non_neg_integer()

Returns the number of keys in ord_map.

Examples

iex> ord_map = A.OrdMap.new(a: "Ant", b: "Bat", c: "Cat")
iex> A.OrdMap.size(ord_map)
3
iex> A.OrdMap.size(A.OrdMap.new())
0

Returns a new ordered map with all the key-value pairs in ord_map where the key is in keys.

If keys contains keys that are not in ord_map, they're simply ignored. Respects the order of the keys list.

Examples

iex> ord_map = A.OrdMap.new(a: "Ant", b: "Bat", c: "Cat")
iex> A.OrdMap.take(ord_map, [:c, :e, :a])
#A<ord(%{c: "Cat", a: "Ant"})>

Specs

to_list(t(k, v)) :: [{k, v}] when k: key(), v: value()

Returns all values from ord_map.

Examples

iex> ord_map = A.OrdMap.new(b: "Bat", c: "Cat", a: "Ant")
iex> A.OrdMap.to_list(ord_map)
[b: "Bat", c: "Cat", a: "Ant"]
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update(ord_map, key, default, fun)

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Specs

update(t(k, v), k, v, (k -> v)) :: t(k, v) when k: key(), v: value()

Puts a value under key only if the key already exists in ord_map.

Examples

iex> ord_map = A.OrdMap.new(a: "Ant", b: "Bat", c: "Cat")
iex> A.OrdMap.update(ord_map, :b, "N/A", &String.upcase/1)
#A<ord(%{a: "Ant", b: "BAT", c: "Cat"})>
iex> A.OrdMap.update(ord_map, :z, "N/A", &String.upcase/1)
#A<ord(%{a: "Ant", b: "Bat", c: "Cat", z: "N/A"})>
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update!(ord_map, key, fun)

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Specs

update!(t(k, v), k, v) :: t(k, v) when k: key(), v: value()

Puts a value under key only if the key already exists in ord_map.

If key is not present in ord_map, a KeyError exception is raised.

Examples

iex> ord_map = A.OrdMap.new(a: "Ant", b: "Bat", c: "Cat")
iex> A.OrdMap.update!(ord_map, :b,  &String.upcase/1)
#A<ord(%{a: "Ant", b: "BAT", c: "Cat"})>
iex> A.OrdMap.update!(ord_map, :d, &String.upcase/1)
** (KeyError) key :d not found in: #A<ord(%{a: "Ant", b: "Bat", c: "Cat"})>

Specs

values(t(key(), v)) :: [v] when v: value()

Returns all values from ord_map.

Examples

iex> ord_map = A.OrdMap.new(b: "Bat", c: "Cat", a: "Ant")
iex> A.OrdMap.values(ord_map)
["Bat", "Cat", "Ant"]