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compress.go
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compress.go
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package grange
import (
"fmt"
"regexp"
"sort"
"strconv"
"strings"
"vbom.ml/util/sortorder"
)
var (
_ = fmt.Println
)
// Normalizes a result set into a minimal range expression, such as
// +{foo,bar}.example.com+.
func Compress(nodes *Result) string {
noDomain := []string{}
domains := map[string][]string{}
for node := range nodes.Iter() {
tokens := strings.SplitN(node.(string), ".", 2)
if len(tokens) == 2 {
domains[tokens[1]] = append(domains[tokens[1]], tokens[0])
} else {
noDomain = append(noDomain, node.(string))
}
}
sort.Sort(sortorder.Natural(noDomain))
result := compressNumeric(noDomain)
var domainKeys = []string{}
for domain, _ := range domains {
domainKeys = append(domainKeys, domain)
}
sort.Sort(sortorder.Natural(domainKeys))
for _, domain := range domainKeys {
domainNodes := domains[domain]
sort.Sort(sortorder.Natural(domainNodes))
domainNodes = compressNumeric(domainNodes)
joined := strings.Join(domainNodes, ",")
if len(domainNodes) > 1 {
joined = "{" + joined + "}"
}
result = append(result, joined+"."+domain)
}
return strings.Join(result, ",")
}
func numericExpansionFor(prefix string, start string, end string, suffix string) string {
endN, _ := strconv.Atoi(end)
startN, _ := strconv.Atoi(start)
if startN == endN {
return fmt.Sprintf("%s%s%s", prefix, end, suffix)
} else {
return fmt.Sprintf("%s%s..%d%s", prefix, start, endN, suffix)
}
}
func compressNumeric(nodes []string) []string {
r := regexp.MustCompile("^(.*?)(\\d+)([^\\d]*)$")
result := []string{}
currentPrefix := ""
currentSuffix := ""
currentNstr := ""
start := ""
startN := -1
currentN := -1
flush := func() {
if startN > -1 {
result = append(result, numericExpansionFor(currentPrefix, start, currentNstr, currentSuffix))
startN = -1
currentPrefix = ""
currentSuffix = ""
currentN = -1
currentNstr = ""
}
}
for _, node := range nodes {
match := r.FindStringSubmatch(node)
if match == nil {
flush()
result = append(result, node)
} else {
prefix := match[1]
n := match[2]
suffix := match[3]
if prefix != currentPrefix || suffix != currentSuffix {
flush()
}
//if len(n) != len(currentNstr) {
//flush
newN, _ := strconv.Atoi(n)
if zeroCount(n) != zeroCount(currentNstr) && len(n) != len(currentNstr) {
flush()
}
if startN < 0 || newN != currentN+1 {
// first in run
flush()
start = n
startN = newN
}
currentNstr = n
currentN = newN
currentPrefix = prefix
currentSuffix = suffix
}
}
flush()
return result
}
func zeroCount(n string) int {
count := 0
for _, c := range n {
if c != '0' {
break
}
count++
}
return count
}