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Merge pull request #154 from synyx/range-rules
Range rules
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,107 @@ | ||
| package config | ||
|
|
||
| import ( | ||
| "math" | ||
| "regexp" | ||
| "strconv" | ||
| ) | ||
|
|
||
| const ( | ||
| gt = iota | ||
| eq | ||
| ge | ||
| lt | ||
| le | ||
| ) | ||
|
|
||
| type RuleMatcher interface { | ||
| MatchString(s string) bool | ||
| } | ||
|
|
||
| var prefixMatcher = regexp.MustCompile(`^(~=|>|<|=|<=|>=)\s+(.*)`) | ||
|
|
||
| func ParseRuleMatcher(value string) RuleMatcher { | ||
| matches := prefixMatcher.FindStringSubmatch(value) | ||
| if matches != nil { | ||
| prefix := matches[1] | ||
| value := matches[2] | ||
| switch prefix { | ||
| case "~=": | ||
| return regexpMatcher{regexp.MustCompile(value)} | ||
| case ">": | ||
| return newNumberMatcher(gt, value) | ||
| case "=": | ||
| if _, err := strconv.ParseFloat(value[2:], 64); err == nil { | ||
| return newNumberMatcher(eq, value[2:]) | ||
| } else { | ||
| return equalityMatcher{value[2:]} | ||
| } | ||
| case "<": | ||
| return newNumberMatcher(lt, value) | ||
| case "<=": | ||
| return newNumberMatcher(le, value) | ||
| case ">=": | ||
| return newNumberMatcher(ge, value) | ||
| } | ||
| } | ||
|
|
||
| return regexpMatcher{regexp.MustCompile(value)} | ||
| } | ||
|
|
||
| type regexpMatcher struct { | ||
| r *regexp.Regexp | ||
| } | ||
|
|
||
| func (m regexpMatcher) MatchString(s string) bool { | ||
| return m.r.MatchString(s) | ||
| } | ||
|
|
||
| type numberMatcher struct { | ||
| operation int | ||
| number float64 | ||
| } | ||
|
|
||
| func newNumberMatcher(op int, s string) numberMatcher { | ||
| number, err := strconv.ParseFloat(s, 64) | ||
| if err != nil { | ||
| panic("config parsing error") | ||
| } | ||
| return numberMatcher{op, number} | ||
| } | ||
|
|
||
| func (m numberMatcher) MatchString(s string) bool { | ||
| number, err := strconv.ParseFloat(s, 64) | ||
| if err != nil { | ||
| // an invalid number cannot be compared, thus returns as non-matching | ||
| return false | ||
| } | ||
|
|
||
| switch m.operation { | ||
| case gt: | ||
| return !floatEqualEnough(m.number, number) && number > m.number | ||
| case eq: | ||
| return floatEqualEnough(m.number, number) | ||
| case ge: | ||
| return floatEqualEnough(m.number, number) || number > m.number | ||
| case lt: | ||
| return !floatEqualEnough(m.number, number) && number < m.number | ||
| case le: | ||
| return floatEqualEnough(m.number, number) || number < m.number | ||
| } | ||
|
|
||
| return false | ||
| } | ||
|
|
||
| const epsilon = 1e-8 | ||
|
|
||
| func floatEqualEnough(a, b float64) bool { | ||
| return math.Abs(a-b) <= epsilon | ||
| } | ||
|
|
||
| type equalityMatcher struct { | ||
| s string | ||
| } | ||
|
|
||
| func (m equalityMatcher) MatchString(s string) bool { | ||
| return m.s == s | ||
| } |