src.elv.sh@v0.21.0-dev.0.20240515223629-06979efb9a2a/pkg/persistent/hashmap/map.go (about)

     1  package hashmap
     2  
     3  import "encoding/json"
     4  
     5  // Map is a persistent associative data structure mapping keys to values. It
     6  // is immutable, and supports near-O(1) operations to create modified version of
     7  // the map that shares the underlying data structure. Because it is immutable,
     8  // all of its methods are safe for concurrent use.
     9  type Map interface {
    10  	json.Marshaler
    11  	// Len returns the length of the map.
    12  	Len() int
    13  	// Index returns whether there is a value associated with the given key, and
    14  	// that value or nil.
    15  	Index(k any) (any, bool)
    16  	// Assoc returns an almost identical map, with the given key associated with
    17  	// the given value.
    18  	Assoc(k, v any) Map
    19  	// Dissoc returns an almost identical map, with the given key associated
    20  	// with no value.
    21  	Dissoc(k any) Map
    22  	// Iterator returns an iterator over the map.
    23  	Iterator() Iterator
    24  }
    25  
    26  // Iterator is an iterator over map elements. It can be used like this:
    27  //
    28  //	for it := m.Iterator(); it.HasElem(); it.Next() {
    29  //	    key, value := it.Elem()
    30  //	    // do something with elem...
    31  //	}
    32  type Iterator interface {
    33  	// Elem returns the current key-value pair.
    34  	Elem() (any, any)
    35  	// HasElem returns whether the iterator is pointing to an element.
    36  	HasElem() bool
    37  	// Next moves the iterator to the next position.
    38  	Next()
    39  }
    40  
    41  // HasKey reports whether a Map has the given key.
    42  func HasKey(m Map, k any) bool {
    43  	_, ok := m.Index(k)
    44  	return ok
    45  }