func trimDuplicates()

in klogr/klogr.go [76:116]

• 21 lines of code
• 5 McCabe index (conditional complexity)

func trimDuplicates(kvLists ...[]interface{}) [][]interface{} {
	// maintain a map of all seen keys
	seenKeys := map[interface{}]struct{}{}
	// build the same number of output slices as inputs
	outs := make([][]interface{}, len(kvLists))
	// iterate over the input slices backwards, as 'later' kv specifications
	// of the same key will take precedence over earlier ones
	for i := len(kvLists) - 1; i >= 0; i-- {
		// initialise this output slice
		outs[i] = []interface{}{}
		// obtain a reference to the kvList we are processing
		kvList := kvLists[i]

		// start iterating at len(kvList) - 2 (i.e. the 2nd last item) for
		// slices that have an even number of elements.
		// We add (len(kvList) % 2) here to handle the case where there is an
		// odd number of elements in a kvList.
		// If there is an odd number, then the last element in the slice will
		// have the value 'null'.
		for i2 := len(kvList) - 2 + (len(kvList) % 2); i2 >= 0; i2 -= 2 {
			k := kvList[i2]
			// if we have already seen this key, do not include it again
			if _, ok := seenKeys[k]; ok {
				continue
			}
			// make a note that we've observed a new key
			seenKeys[k] = struct{}{}
			// attempt to obtain the value of the key
			var v interface{}
			// i2+1 should only ever be out of bounds if we handling the first
			// iteration over a slice with an odd number of elements
			if i2+1 < len(kvList) {
				v = kvList[i2+1]
			}
			// add this KV tuple to the *start* of the output list to maintain
			// the original order as we are iterating over the slice backwards
			outs[i] = append([]interface{}{k, v}, outs[i]...)
		}
	}
	return outs
}