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Simple golang RangeMap implementation for sorted, not overlapping ranges of integers (like IP address ranges). Elements are found using binary search.
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package main | |
import ( | |
"fmt" | |
"sort" | |
) | |
type Range struct { | |
L int | |
U int | |
} | |
type RangeMap struct { | |
Keys []Range | |
Values []string | |
} | |
// works like Guava RangeMap com.google.common.collect.ImmutableRangeMap | |
// https://github.com/google/guava/blob/1efc5ce983c02cfaa2ce3338bdfaa1f583b66128/guava/src/com/google/common/collect/ImmutableRangeMap.java#L159 | |
func (rm RangeMap) Get(key int) (string, bool) { | |
i := sort.Search(len(rm.Keys), func(i int) bool { | |
fmt.Printf("search %v at index %d for %v is %v\n", rm.Keys[i], i, key, key < rm.Keys[i].L) | |
return key < rm.Keys[i].L | |
}) | |
i -= 1 | |
if i >= 0 && i < len(rm.Keys) && key <= rm.Keys[i].U { | |
return rm.Values[i], true | |
} | |
return "", false | |
} | |
func main() { | |
rangeMap := RangeMap{ []Range{Range{1,2}, Range{3,4}, Range{6,8}, Range{12,16}, Range{17,18}}, | |
[]string{"a","b","c","d","e"} } | |
x := 14 | |
value, ok := rangeMap.Get(x) | |
fmt.Printf("found %v '%s' for %d\n", ok, value, x) | |
x = 5 | |
value, ok = rangeMap.Get(x) | |
fmt.Printf("found %v '%s' for %d\n", ok, value, x) | |
} | |
// search {6 8} at index 2 for 14 is false | |
// search {17 18} at index 4 for 14 is true | |
// search {12 16} at index 3 for 14 is false | |
// found true 'd' for 14 | |
// search {6 8} at index 2 for 5 is true | |
// search {3 4} at index 1 for 5 is false | |
// found false '' for 5 |
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