github.com/songzhibin97/go-baseutils@v0.0.2-0.20240302024150-487d8ce9c082/structure/maps/linkedhashmap/iterator.go (about)

     1  package linkedhashmap
     2  
     3  import (
     4  	"github.com/songzhibin97/go-baseutils/structure/lists/doublylinkedlist"
     5  )
     6  
     7  // Iterator holding the iterator's state
     8  type Iterator[K comparable, V any] struct {
     9  	iterator doublylinkedlist.Iterator[K]
    10  	table    map[K]V
    11  }
    12  
    13  // Iterator returns a stateful iterator whose elements are key/value pairs.
    14  func (m *Map[K, V]) Iterator() Iterator[K, V] {
    15  	return Iterator[K, V]{
    16  		iterator: m.ordering.Iterator(),
    17  		table:    m.table,
    18  	}
    19  }
    20  
    21  // Next moves the iterator to the next element and returns true if there was a next element in the container.
    22  // If Next() returns true, then next element's key and value can be retrieved by Key() and Value().
    23  // If Next() was called for the first time, then it will point the iterator to the first element if it exists.
    24  // Modifies the state of the iterator.
    25  func (iterator *Iterator[K, V]) Next() bool {
    26  	return iterator.iterator.Next()
    27  }
    28  
    29  // Prev moves the iterator to the previous element and returns true if there was a previous element in the container.
    30  // If Prev() returns true, then previous element's key and value can be retrieved by Key() and Value().
    31  // Modifies the state of the iterator.
    32  func (iterator *Iterator[K, V]) Prev() bool {
    33  	return iterator.iterator.Prev()
    34  }
    35  
    36  // Value returns the current element's value.
    37  // Does not modify the state of the iterator.
    38  func (iterator *Iterator[K, V]) Value() V {
    39  	key := iterator.iterator.Value()
    40  	return iterator.table[key]
    41  }
    42  
    43  // Key returns the current element's key.
    44  // Does not modify the state of the iterator.
    45  func (iterator *Iterator[K, V]) Key() K {
    46  	return iterator.iterator.Value()
    47  }
    48  
    49  // Begin resets the iterator to its initial state (one-before-first)
    50  // Call Next() to fetch the first element if any.
    51  func (iterator *Iterator[K, V]) Begin() {
    52  	iterator.iterator.Begin()
    53  }
    54  
    55  // End moves the iterator past the last element (one-past-the-end).
    56  // Call Prev() to fetch the last element if any.
    57  func (iterator *Iterator[K, V]) End() {
    58  	iterator.iterator.End()
    59  }
    60  
    61  // First moves the iterator to the first element and returns true if there was a first element in the container.
    62  // If First() returns true, then first element's key and value can be retrieved by Key() and Value().
    63  // Modifies the state of the iterator
    64  func (iterator *Iterator[K, V]) First() bool {
    65  	return iterator.iterator.First()
    66  }
    67  
    68  // Last moves the iterator to the last element and returns true if there was a last element in the container.
    69  // If Last() returns true, then last element's key and value can be retrieved by Key() and Value().
    70  // Modifies the state of the iterator.
    71  func (iterator *Iterator[K, V]) Last() bool {
    72  	return iterator.iterator.Last()
    73  }
    74  
    75  // NextTo moves the iterator to the next element from current position that satisfies the condition given by the
    76  // passed function, and returns true if there was a next element in the container.
    77  // If NextTo() returns true, then next element's key and value can be retrieved by Key() and Value().
    78  // Modifies the state of the iterator.
    79  func (iterator *Iterator[K, V]) NextTo(f func(key K, value V) bool) bool {
    80  	for iterator.Next() {
    81  		key, value := iterator.Key(), iterator.Value()
    82  		if f(key, value) {
    83  			return true
    84  		}
    85  	}
    86  	return false
    87  }
    88  
    89  // PrevTo moves the iterator to the previous element from current position that satisfies the condition given by the
    90  // passed function, and returns true if there was a next element in the container.
    91  // If PrevTo() returns true, then next element's key and value can be retrieved by Key() and Value().
    92  // Modifies the state of the iterator.
    93  func (iterator *Iterator[K, V]) PrevTo(f func(key K, value V) bool) bool {
    94  	for iterator.Prev() {
    95  		key, value := iterator.Key(), iterator.Value()
    96  		if f(key, value) {
    97  			return true
    98  		}
    99  	}
   100  	return false
   101  }