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109 lines
2.8 KiB
Go
109 lines
2.8 KiB
Go
// Copyright (c) 2015, Emir Pasic. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package linkedhashmap is a map that preserves insertion-order.
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//
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// It is backed by a hash table to store values and doubly-linked list to store ordering.
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//
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// Structure is not thread safe.
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//
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// Reference: http://en.wikipedia.org/wiki/Associative_array
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package linkedhashmap
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import (
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"fmt"
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"github.com/emirpasic/gods/lists/doublylinkedlist"
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"github.com/emirpasic/gods/maps"
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"strings"
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)
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// Assert Map implementation
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var _ maps.Map = (*Map)(nil)
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// Map holds the elements in a regular hash table, and uses doubly-linked list to store key ordering.
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type Map struct {
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table map[interface{}]interface{}
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ordering *doublylinkedlist.List
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}
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// New instantiates a linked-hash-map.
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func New() *Map {
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return &Map{
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table: make(map[interface{}]interface{}),
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ordering: doublylinkedlist.New(),
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}
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}
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// Put inserts key-value pair into the map.
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// Key should adhere to the comparator's type assertion, otherwise method panics.
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func (m *Map) Put(key interface{}, value interface{}) {
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if _, contains := m.table[key]; !contains {
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m.ordering.Append(key)
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}
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m.table[key] = value
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}
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// Get searches the element in the map by key and returns its value or nil if key is not found in tree.
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// Second return parameter is true if key was found, otherwise false.
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// Key should adhere to the comparator's type assertion, otherwise method panics.
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func (m *Map) Get(key interface{}) (value interface{}, found bool) {
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value = m.table[key]
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found = value != nil
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return
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}
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// Remove removes the element from the map by key.
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// Key should adhere to the comparator's type assertion, otherwise method panics.
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func (m *Map) Remove(key interface{}) {
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if _, contains := m.table[key]; contains {
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delete(m.table, key)
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index := m.ordering.IndexOf(key)
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m.ordering.Remove(index)
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}
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}
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// Empty returns true if map does not contain any elements
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func (m *Map) Empty() bool {
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return m.Size() == 0
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}
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// Size returns number of elements in the map.
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func (m *Map) Size() int {
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return m.ordering.Size()
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}
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// Keys returns all keys in-order
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func (m *Map) Keys() []interface{} {
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return m.ordering.Values()
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}
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// Values returns all values in-order based on the key.
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func (m *Map) Values() []interface{} {
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values := make([]interface{}, m.Size())
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count := 0
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it := m.Iterator()
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for it.Next() {
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values[count] = it.Value()
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count++
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}
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return values
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}
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// Clear removes all elements from the map.
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func (m *Map) Clear() {
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m.table = make(map[interface{}]interface{})
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m.ordering.Clear()
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}
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// String returns a string representation of container
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func (m *Map) String() string {
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str := "LinkedHashMap\nmap["
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it := m.Iterator()
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for it.Next() {
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str += fmt.Sprintf("%v:%v ", it.Key(), it.Value())
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}
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return strings.TrimRight(str, " ") + "]"
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}
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