Accessing Random Rune Element of a String Efficiently
In Go, strings are represented as a sequence of UTF-8 encoded bytes. To access a rune element at a specific index, one can iterate through the string using a for ... range loop. However, this method can be inefficient for frequent access.
The reason for this inefficiency is that Go's strings are not directly indexed over runes. To extract a rune, the UTF-8 byte sequence must be decoded. This decoding overhead becomes significant if the function is called multiple times.
To optimize performance, it is recommended to avoid using a string and instead use a []rune slice. Slices are efficiently indexed, allowing for direct access to runes. If the input type cannot be changed, a cache can be implemented to store decoded []rune representations of strings.
Here is a modified version of the provided function that utilizes a cache:
var cache = map[string][]rune{} func RuneAt(s string, idx int) rune { rs := cache[s] if rs == nil { rs = []rune(s) cache[s] = []rune(s) } if idx >= len(rs) { return 0 } return rs[idx] }
The cache stores the decoded []rune representations of strings to avoid repetitive decoding. This approach can significantly improve performance if RuneAt() is called with a limited set of strings.
The above is the detailed content of How Can I Efficiently Access a Random Rune in a Go String?. For more information, please follow other related articles on the PHP Chinese website!

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