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How to canonicalize strings to save memory?

At run time of Go programs, sometimes, some equal strings don't share underlying bytes memory blocks, even if they can share a single common bytes memory block.

The process to let them share a single common bytes memory block is called string canonicalization. There are several ways in Go to implement string canonicalization.

Way 1: canonicalize two strings when they are found equal

The logic and implementation is simple: 

	if str1 == str2 {
		str1 = str2 // give up str2's underlying bytes memory block
	}

Here is a clumsy implementation to canonicalize the strings in a slice: 

func CanonicalizeStrings(ss []string) {
	type S struct {
		str   string
		index int
	}
	var temp = make([]S, len(ss))
	for i := range temp {
		temp[i] = S {
			str: ss[i],
			index: i,
		}
	}
	
	for i := 0; i < len(temp); {
		var k = i+1
		for j := k; j < len(temp); j++ {
			if temp[j].str == temp[i].str {
				temp[j].str = temp[i].str
				temp[k], temp[j] = temp[j], temp[k]
				k++
			}
		}
		i = k
	}
	
	for i := range temp {
		ss[temp[i].index] = temp[i].str
	}
}

The way is more performant than the following way for the specified case (canonicalize all strings in a slice).

Way 2: use Go 1.23 introduced unique.Handle

Go 1.23 introduced unique.Handle is a convenient way to canonicalize strings. 

import "unique"

func CanonicalizeString(s string) string {
	return unique.Make(s).Value()
}

func CanonicalizeStrings(ss []string) {
	for i, s := range ss {
		ss[i] = CanonicalizeString(s)
	}
}

The way is more flexible. Just apply the above CanonicalizeString function for every string used at run time, then all equal strings will share the same underlying bytes memory blocks.

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