How Can I Iterate Through a Go Map in the Order of Insertion?

Iterating a Go Map in Order of Insertion

Conventional wisdom suggests that the iteration order of Go maps is unpredictable and unstable. However, achieving order preservation requires utilizing alternative data structures that maintain the insertion sequence independently:

1. Tracking Keys in a Separate Slice:

By maintaining a slice of keys in the order they were inserted, you can iterate over the keys and retrieve their corresponding values from the map. This eliminates the need for duplicated data and provides a reliable iteration sequence.

2. Using a Value Wrapper with a Linked List:

Another approach involves wrapping each value in the map with a struct that includes a reference to the next key in the insertion order. This allows for traversal of the elements in their intended sequence, even after removals or insertions.

Comparison:

Both methods retain the advantages of using maps while providing ordered iteration. However, the approach with a separate slice for keys has a simpler implementation but may incur an overhead when removing elements. The linked-list approach offers faster removal but introduces more complexity.

Code Snippets:

Keys in a Slice:

Value Wrapper with Linked List:

By employing these techniques, you can efficiently iterate through a Go map and retrieve items in the order they were originally inserted.

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