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OrderedDictionary+Initializers.swift
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OrderedDictionary+Initializers.swift
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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift Collections open source project
//
// Copyright (c) 2021 - 2024 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
//
//===----------------------------------------------------------------------===//
#if !COLLECTIONS_SINGLE_MODULE
import InternalCollectionsUtilities
#endif
extension OrderedDictionary {
/// Creates an empty dictionary.
///
/// This initializer is equivalent to initializing with an empty dictionary
/// literal.
///
/// - Complexity: O(1)
@inlinable
@inline(__always)
public init() {
self._keys = OrderedSet()
self._values = []
}
/// Creates an empty dictionary with preallocated space for at least the
/// specified number of elements.
///
/// Use this initializer to avoid intermediate reallocations of a dictionary's
/// storage buffer when you know in advance how many elements you'll insert
/// into it after creation.
///
/// If you have a good idea of the expected working size of the dictionary,
/// calling this initializer with `persistent` set to true can sometimes
/// improve performance by eliminating churn due to repeated rehashings when
/// the dictionary temporarily shrinks below its regular size. You can cancel
/// any capacity you've previously reserved by persistently reserving a
/// capacity of zero. (This also shrinks the hash table to the ideal size for
/// its current number elements.)
///
/// - Parameter minimumCapacity: The minimum number of elements that the newly
/// created dictionary should be able to store without reallocating its
/// storage.
///
/// - Parameter persistent: If set to true, prevent removals from shrinking
/// storage below the specified capacity. By default, removals are allowed
/// to shrink storage below any previously reserved capacity.
///
/// - Complexity: O(`minimumCapacity`)
@inlinable
@inline(__always)
public init(minimumCapacity: Int, persistent: Bool = false) {
self._keys = OrderedSet(minimumCapacity: minimumCapacity, persistent: persistent)
self._values = []
_values.reserveCapacity(minimumCapacity)
}
}
extension OrderedDictionary {
/// Creates a new dictionary from the key-value pairs in the given sequence.
///
/// You use this initializer to create a dictionary when you have a sequence
/// of key-value tuples with unique keys. Passing a sequence with duplicate
/// keys to this initializer results in a runtime error. If your
/// sequence might have duplicate keys, use the
/// `Dictionary(_:uniquingKeysWith:)` initializer instead.
///
/// - Parameter keysAndValues: A sequence of key-value pairs to use for
/// the new dictionary. Every key in `keysAndValues` must be unique.
///
/// - Returns: A new dictionary initialized with the elements of
/// `keysAndValues`.
///
/// - Precondition: The sequence must not have duplicate keys.
///
/// - Complexity: Expected O(*n*) on average, where *n* is the count if
/// key-value pairs, if `Key` implements high-quality hashing.
@_disfavoredOverload // https://github.com/apple/swift-collections/issues/125
@inlinable
public init(
uniqueKeysWithValues keysAndValues: some Sequence<(key: Key, value: Value)>
) {
if let keysAndValues = _specialize(
keysAndValues, for: Dictionary<Key, Value>.self
) {
self.init(_uncheckedUniqueKeysWithValues: keysAndValues)
return
}
self.init()
reserveCapacity(keysAndValues.underestimatedCount)
for (key, value) in keysAndValues {
guard _keys._append(key).inserted else {
preconditionFailure("Duplicate key: '\(key)'")
}
_values.append(value)
}
}
/// Creates a new dictionary from the key-value pairs in the given sequence.
///
/// You use this initializer to create a dictionary when you have a sequence
/// of key-value tuples with unique keys. Passing a sequence with duplicate
/// keys to this initializer results in a runtime error. If your
/// sequence might have duplicate keys, use the
/// `Dictionary(_:uniquingKeysWith:)` initializer instead.
///
/// - Parameter keysAndValues: A sequence of key-value pairs to use for
/// the new dictionary. Every key in `keysAndValues` must be unique.
///
/// - Returns: A new dictionary initialized with the elements of
/// `keysAndValues`.
///
/// - Precondition: The sequence must not have duplicate keys.
///
/// - Complexity: Expected O(*n*) on average, where *n* is the count if
/// key-value pairs, if `Key` implements high-quality hashing.
@inlinable
public init(
uniqueKeysWithValues keysAndValues: some Sequence<(Key, Value)>
) {
self.init()
reserveCapacity(keysAndValues.underestimatedCount)
for (key, value) in keysAndValues {
guard _keys._append(key).inserted else {
preconditionFailure("Duplicate key: '\(key)'")
}
_values.append(value)
}
}
}
extension OrderedDictionary {
/// Creates a new dictionary from separate sequences of keys and values.
///
/// You use this initializer to create a dictionary when you have two
/// sequences with unique keys and their associated values, respectively.
/// Passing a `keys` sequence with duplicate keys to this initializer results
/// in a runtime error.
///
/// - Parameter keys: A sequence of unique keys.
///
/// - Parameter values: A sequence of values associated with items in `keys`.
///
/// - Returns: A new dictionary initialized with the data in
/// `keys` and `values`.
///
/// - Precondition: The sequence must not have duplicate keys, and `keys` and
/// `values` must contain an equal number of elements.
///
/// - Complexity: Expected O(*n*) on average, where *n* is the count if
/// key-value pairs, if `Key` implements high-quality hashing.
@inlinable
public init(
uniqueKeys keys: some Sequence<Key>,
values: some Sequence<Value>
) {
let keys = ContiguousArray(keys)
let values = ContiguousArray(values)
precondition(keys.count == values.count,
"Mismatching element counts between keys and values")
self._keys = .init(keys)
self._values = values
precondition(_keys.count == _values.count, "Duplicate keys")
_checkInvariants()
}
}
extension OrderedDictionary {
/// Creates a new dictionary from the key-value pairs in the given sequence,
/// using a combining closure to determine the value for any duplicate keys.
///
/// You use this initializer to create a dictionary when you have a sequence
/// of key-value tuples that might have duplicate keys. As the dictionary is
/// built, the initializer calls the `combine` closure with the current and
/// new values for any duplicate keys. Pass a closure as `combine` that
/// returns the value to use in the resulting dictionary: The closure can
/// choose between the two values, combine them to produce a new value, or
/// even throw an error.
///
/// let pairsWithDuplicateKeys = [("a", 1), ("b", 2), ("a", 3), ("b", 4)]
///
/// let firstValues = OrderedDictionary(
/// pairsWithDuplicateKeys,
/// uniquingKeysWith: { (first, _) in first })
/// // ["a": 1, "b": 2]
///
/// let lastValues = OrderedDictionary(
/// pairsWithDuplicateKeys,
/// uniquingKeysWith: { (_, last) in last })
/// // ["a": 3, "b": 4]
///
/// - Parameters:
/// - keysAndValues: A sequence of key-value pairs to use for the new
/// dictionary.
/// - combine: A closure that is called with the values for any duplicate
/// keys that are encountered. The closure returns the desired value for
/// the final dictionary.
///
/// - Complexity: Expected O(*n*) on average, where *n* is the count of
/// key-value pairs, if `Key` implements high-quality hashing.
@_disfavoredOverload // https://github.com/apple/swift-collections/issues/125
@inlinable
@inline(__always)
public init(
_ keysAndValues: some Sequence<(key: Key, value: Value)>,
uniquingKeysWith combine: (Value, Value) throws -> Value
) rethrows {
self.init()
try self.merge(keysAndValues, uniquingKeysWith: combine)
}
/// Creates a new dictionary from the key-value pairs in the given sequence,
/// using a combining closure to determine the value for any duplicate keys.
///
/// You use this initializer to create a dictionary when you have a sequence
/// of key-value tuples that might have duplicate keys. As the dictionary is
/// built, the initializer calls the `combine` closure with the current and
/// new values for any duplicate keys. Pass a closure as `combine` that
/// returns the value to use in the resulting dictionary: The closure can
/// choose between the two values, combine them to produce a new value, or
/// even throw an error.
///
/// let pairsWithDuplicateKeys = [("a", 1), ("b", 2), ("a", 3), ("b", 4)]
///
/// let firstValues = OrderedDictionary(
/// pairsWithDuplicateKeys,
/// uniquingKeysWith: { (first, _) in first })
/// // ["a": 1, "b": 2]
///
/// let lastValues = OrderedDictionary(
/// pairsWithDuplicateKeys,
/// uniquingKeysWith: { (_, last) in last })
/// // ["a": 3, "b": 4]
///
/// - Parameters:
/// - keysAndValues: A sequence of key-value pairs to use for the new
/// dictionary.
/// - combine: A closure that is called with the values for any duplicate
/// keys that are encountered. The closure returns the desired value for
/// the final dictionary.
///
/// - Complexity: Expected O(*n*) on average, where *n* is the count of
/// key-value pairs, if `Key` implements high-quality hashing.
@inlinable
@inline(__always)
public init(
_ keysAndValues: some Sequence<(Key, Value)>,
uniquingKeysWith combine: (Value, Value) throws -> Value
) rethrows {
self.init()
try self.merge(keysAndValues, uniquingKeysWith: combine)
}
}
extension OrderedDictionary {
/// Creates a new dictionary whose keys are the groupings returned by the
/// given closure and whose values are arrays of the elements that returned
/// each key.
///
/// The arrays in the "values" position of the new dictionary each contain at
/// least one element, with the elements in the same order as the source
/// sequence.
///
/// The following example declares an array of names, and then creates a
/// dictionary from that array by grouping the names by first letter:
///
/// let students = ["Kofi", "Abena", "Efua", "Kweku", "Akosua"]
/// let studentsByLetter = OrderedDictionary(grouping: students, by: { $0.first! })
/// // ["K": ["Kofi", "Kweku"], "A": ["Abena", "Akosua"], "E": ["Efua"]]
///
/// The new `studentsByLetter` dictionary has three entries, with students'
/// names grouped by the keys `"E"`, `"K"`, and `"A"`.
///
/// - Parameters:
/// - values: A sequence of values to group into a dictionary.
/// - keyForValue: A closure that returns a key for each element in
/// `values`.
///
/// - Complexity: Expected O(*n*) on average, where *n* is the count of
/// values, if `Key` implements high-quality hashing.
@inlinable
public init<S: Sequence>(
grouping values: S,
by keyForValue: (S.Element) throws -> Key
) rethrows where Value: RangeReplaceableCollection, Value.Element == S.Element {
try self.init(_grouping: values, by: keyForValue)
}
/// Creates a new dictionary whose keys are the groupings returned by the
/// given closure and whose values are arrays of the elements that returned
/// each key.
///
/// The arrays in the "values" position of the new dictionary each contain at
/// least one element, with the elements in the same order as the source
/// sequence.
///
/// The following example declares an array of names, and then creates a
/// dictionary from that array by grouping the names by first letter:
///
/// let students = ["Kofi", "Abena", "Efua", "Kweku", "Akosua"]
/// let studentsByLetter = OrderedDictionary(grouping: students, by: { $0.first! })
/// // ["K": ["Kofi", "Kweku"], "A": ["Abena", "Akosua"], "E": ["Efua"]]
///
/// The new `studentsByLetter` dictionary has three entries, with students'
/// names grouped by the keys `"E"`, `"K"`, and `"A"`.
///
/// - Parameters:
/// - values: A sequence of values to group into a dictionary.
/// - keyForValue: A closure that returns a key for each element in
/// `values`.
///
/// - Complexity: Expected O(*n*) on average, where *n* is the count of
/// values, if `Key` implements high-quality hashing.
@inlinable
public init<S: Sequence>(
grouping values: S,
by keyForValue: (S.Element) throws -> Key
) rethrows where Value == [S.Element] {
// Note: this extra overload is necessary to make type inference work
// for the `Value` type -- we want it to default to `[S.Element`].
// (https://github.com/apple/swift-collections/issues/139)
try self.init(_grouping: values, by: keyForValue)
}
@inlinable
internal init<S: Sequence>(
_grouping values: S,
by keyForValue: (S.Element) throws -> Key
) rethrows where Value: RangeReplaceableCollection, Value.Element == S.Element {
self.init()
for value in values {
let key = try keyForValue(value)
self.updateValue(forKey: key, default: Value()) { array in
array.append(value)
}
}
}
}
extension OrderedDictionary {
@inlinable
internal init(
_uncheckedUniqueKeysWithValues keysAndValues:
some Sequence<(key: Key, value: Value)>
) {
self.init()
reserveCapacity(keysAndValues.underestimatedCount)
for (key, value) in keysAndValues {
_keys._appendNew(key)
_values.append(value)
}
_checkInvariants()
}
/// Creates a new dictionary from the key-value pairs in the given sequence,
/// which must not contain duplicate keys.
///
/// In optimized builds, this initializer does not verify that the keys are
/// actually unique. This makes creating the dictionary somewhat faster if you
/// know for sure that the elements are unique (e.g., because they come from
/// another collection with guaranteed-unique members, such as a
/// `Dictionary`). However, if you accidentally call this initializer with
/// duplicate members, it can return a corrupt dictionary value that may be
/// difficult to debug.
///
/// - Parameter keysAndValues: A sequence of key-value pairs to use for
/// the new dictionary. Every key in `keysAndValues` must be unique.
///
/// - Returns: A new dictionary initialized with the elements of
/// `keysAndValues`.
///
/// - Precondition: The sequence must not have duplicate keys.
///
/// - Complexity: Expected O(*n*) on average, where *n* is the count if
/// key-value pairs, if `Key` implements high-quality hashing.
@_disfavoredOverload // https://github.com/apple/swift-collections/issues/125
@inlinable
public init(
uncheckedUniqueKeysWithValues keysAndValues:
some Sequence<(key: Key, value: Value)>
) {
#if DEBUG
self.init(uniqueKeysWithValues: keysAndValues)
#else
self.init(_uncheckedUniqueKeysWithValues: keysAndValues)
#endif
}
/// Creates a new dictionary from the key-value pairs in the given sequence,
/// which must not contain duplicate keys.
///
/// In optimized builds, this initializer does not verify that the keys are
/// actually unique. This makes creating the dictionary somewhat faster if you
/// know for sure that the elements are unique (e.g., because they come from
/// another collection with guaranteed-unique members, such as a
/// `Dictionary`). However, if you accidentally call this initializer with
/// duplicate members, it can return a corrupt dictionary value that may be
/// difficult to debug.
///
/// - Parameter keysAndValues: A sequence of key-value pairs to use for
/// the new dictionary. Every key in `keysAndValues` must be unique.
///
/// - Returns: A new dictionary initialized with the elements of
/// `keysAndValues`.
///
/// - Precondition: The sequence must not have duplicate keys.
///
/// - Complexity: Expected O(*n*) on average, where *n* is the count if
/// key-value pairs, if `Key` implements high-quality hashing.
@inlinable
public init(
uncheckedUniqueKeysWithValues keysAndValues: some Sequence<(Key, Value)>
) {
// Add tuple labels
let keysAndValues = keysAndValues.lazy.map { (key: $0.0, value: $0.1) }
self.init(uncheckedUniqueKeysWithValues: keysAndValues)
}
}
extension OrderedDictionary {
/// Creates a new dictionary from separate sequences of unique keys and
/// associated values.
///
/// In optimized builds, this initializer does not verify that the keys are
/// actually unique. This makes creating the dictionary somewhat faster if you
/// know for sure that the elements are unique (e.g., because they come from
/// another collection with guaranteed-unique members, such as a
/// `Dictionary`). However, if you accidentally call this initializer with
/// duplicate members, it can return a corrupt dictionary value that may be
/// difficult to debug.
///
/// - Parameter keys: A sequence of unique keys.
///
/// - Parameter values: A sequence of values associated with items in `keys`.
///
/// - Returns: A new dictionary initialized with the data in
/// `keys` and `values`.
///
/// - Precondition: The sequence must not have duplicate keys, and `keys` and
/// `values` must contain an equal number of elements.
///
/// - Complexity: Expected O(*n*) on average, where *n* is the count if
/// key-value pairs, if `Key` implements high-quality hashing.
@inlinable
@inline(__always)
public init(
uncheckedUniqueKeys keys: some Sequence<Key>,
values: some Sequence<Value>
) {
#if DEBUG
self.init(uniqueKeys: keys, values: values)
#else
self._keys = .init(uncheckedUniqueElements: keys)
self._values = .init(values)
precondition(_keys.count == _values.count)
_checkInvariants()
#endif
}
}