PHP中的数据结构:DS扩展

2018-06-22 05:23:37来源:未知 阅读 ()

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  PHP7以上才能安装和使用该数据结构扩展,安装比较简单:

1. 运行命令 pecl install ds

2. 在php.ini中添加 extension=ds.so

3. 重启PHP或重载配置

在这些数据结构类型(Class)对象中,除了Pair、PriorityQueue对象之外,其余各种类型(Class)对象都支持数组语法。

  •  Collection Interface:包含本库中所有数据结构通用功能的基本interface。 It guarantees that all structures are traversable, countable, and can be converted to json using json_encode().
    Ds\Collection implements Traversable , Countable , JsonSerializable {
    /* 方法 */
    abstract public void clear ( void )
    abstract public Ds\Collection copy ( void )
    abstract public bool isEmpty ( void )
    abstract public array toArray ( void )
    }
  • Hashable Interfacewhich allows objects to be used as keys.
    Ds\Hashable {
    /* 方法 */
    abstract public bool equals ( object $obj )
    abstract public mixed hash ( void )
    }
  • Sequence InterfaceA Sequence 相当于一个一维的数字key数组, with the exception of a few characteristics:
    • Values will always be indexed as [0, 1, 2, …, size - 1].
    • Only allowed to access values by index in the range [0, size - 1].

    Use cases:

    • Wherever you would use an array as a list (not concerned with keys).
    • A more efficient alternative to SplDoublyLinkedList and SplFixedArray.
  • Vector Class:Vector是自动增长和收缩的连续缓冲区中的一系列值。它是最有效的顺序结构,值的索引直接映射到缓冲区中索引,增长因子不绑定到特定的倍数或指数。其具有以下优缺点:

    • Supports array syntax (square brackets).
    • Uses less overall memory than an array for the same number of values.
    • Automatically frees allocated memory when its size drops low enough.
    • Capacity does not have to be a power of 2.
    • get(), set(), push(), pop() are all O(1).
    • 但是 shift(), unshift(), insert() and remove() are all O(n).
    Ds\Vector::allocate — Allocates enough memory for a required capacity.
    Ds\Vector::apply — Updates all values by applying a callback function to each value.
    Ds\Vector::capacity — Returns the current capacity.
    Ds\Vector::clear — Removes all values.
    Ds\Vector::__construct — Creates a new instance.
    Ds\Vector::contains — Determines if the vector contains given values.
    Ds\Vector::copy — Returns a shallow copy of the vector.
    Ds\Vector::count — Returns the number of values in the collection.
    Ds\Vector::filter — Creates a new vector using a callable to determine which values to include.
    Ds\Vector::find — Attempts to find a value's index.
    Ds\Vector::first — Returns the first value in the vector.
    Ds\Vector::get — Returns the value at a given index.
    Ds\Vector::insert — Inserts values at a given index.
    Ds\Vector::isEmpty — Returns whether the vector is empty
    Ds\Vector::join — Joins all values together as a string.
    Ds\Vector::jsonSerialize — Returns a representation that can be converted to JSON.
    Ds\Vector::last — Returns the last value.
    Ds\Vector::map — Returns the result of applying a callback to each value.
    Ds\Vector::merge — Returns the result of adding all given values to the vector.
    Ds\Vector::pop — Removes and returns the last value.
    Ds\Vector::push — Adds values to the end of the vector.
    Ds\Vector::reduce — Reduces the vector to a single value using a callback function.
    Ds\Vector::remove — Removes and returns a value by index.
    Ds\Vector::reverse — Reverses the vector in-place.
    Ds\Vector::reversed — Returns a reversed copy.
    Ds\Vector::rotate — Rotates the vector by a given number of rotations.
    Ds\Vector::set — Updates a value at a given index.
    Ds\Vector::shift — Removes and returns the first value.
    Ds\Vector::slice — Returns a sub-vector of a given range.
    Ds\Vector::sort — Sorts the vector in-place.
    Ds\Vector::sorted — Returns a sorted copy.
    Ds\Vector::sum — Returns the sum of all values in the vector.
    Ds\Vector::toArray — Converts the vector to an array.
    Ds\Vector::unshift — Adds values to the front of the vector.

     

  • Deque Class:“双端队列”的缩写,也用于Ds\Queue中,拥有head、tail两个指针。The pointers can “wrap around” the end of the buffer, which avoids the need to move other values around to make room. This makes shift and unshift very fast?—? something a Ds\Vector can’t compete with. 其具有以下优缺点:
    • Supports array syntax (square brackets).
    • Uses less overall memory than an array for the same number of values.
    • Automatically frees allocated memory when its size drops low enough.
    • get(), set(), push(), pop(), shift(), and unshift() are all O(1).
    • 但Capacity must be a power of 2.insert() and remove() are O(n).
  • Map Class:键值对的连续集合,几乎与数组相同。键可以是任何类型,但必须是唯一的。如果使用相同的键添加到map中,则将替换值。其拥有以下优缺点:
    • Keys and values can be any type, including objects.
    • Supports array syntax (square brackets).
    • Insertion order is preserved.
    • Performance and memory efficiency is very similar to an array.
    • Automatically frees allocated memory when its size drops low enough.
    • Can’t be converted to an array when objects are used as keys.
  • Pair Class:A pair is used by Ds\Map to pair keys with values.
    Ds\Pair implements JsonSerializable {
    /* 方法 */
    public __construct ([ mixed $key [, mixed $value ]] )
    }
  • Set Class唯一值序列。 This implementation uses the same hash table as Ds\Map, where values are used as keys and the mapped value is ignored.其拥有以下优缺点:
    • Values can be any type, including objects.
    • Supports array syntax (square brackets).
    • Insertion order is preserved.
    • Automatically frees allocated memory when its size drops low enough.
    • add(), remove() and contains() are all O(1).
    • 但Doesn’t support push(), pop(), insert(), shift(), or unshift(). get() is O(n) if there are deleted values in the buffer before the accessed index, O(1) otherwise. 
  • Stack Class: “last in, first out”集合,只允许在结构顶部进行访问和迭代。
    Ds\Stack implements Ds\Collection {
    /* 方法 */
    public void allocate ( int $capacity )
    public int capacity ( void )
    public void clear ( void )
    public Ds\Stack copy ( void )
    public bool isEmpty ( void )
    public mixed peek ( void )
    public mixed pop ( void )
    public void push ([ mixed $...values ] )
    public array toArray ( void )
    }
  • Queue Class“first in, first out”集合,只允许在结构前端进行访问和迭代。
    Ds\Queue implements Ds\Collection {
    /* Constants */
    const int MIN_CAPACITY = 8 ;
    /* 方法 */
    public void allocate ( int $capacity )
    public int capacity ( void )
    public void clear ( void )
    public Ds\Queue copy ( void )
    public bool isEmpty ( void )
    public mixed peek ( void )
    public mixed pop ( void )
    public void push ([ mixed $...values ] )
    public array toArray ( void )
    }
  • PriorityQueue Class:优先级队列与队列是非常相似的,但值以指定的优先级被推入队列,优先级最高的值总是位于队列的前面,同优先级元素“先入先出”顺序任然保留。在一个PriorityQueue上递代是具有破坏性的,相当于连续弹出操作直到队列为空。Implemented using a max heap.
    Ds\PriorityQueue implements Ds\Collection {
    /* Constants */
    const int MIN_CAPACITY = 8 ;
    /* 方法 */
    public void allocate ( int $capacity )
    public int capacity ( void )
    public void clear ( void )
    public Ds\PriorityQueue copy ( void )
    public bool isEmpty ( void )
    public mixed peek ( void )
    public mixed pop ( void )
    public void push ( mixed $value , int $priority )
    public array toArray ( void )
    }

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