1// Copyright 2017 The Prometheus Authors 2// Licensed under the Apache License, Version 2.0 (the "License"); 3// you may not use this file except in compliance with the License. 4// You may obtain a copy of the License at 5// 6// http://www.apache.org/licenses/LICENSE-2.0 7// 8// Unless required by applicable law or agreed to in writing, software 9// distributed under the License is distributed on an "AS IS" BASIS, 10// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 11// See the License for the specific language governing permissions and 12// limitations under the License. 13 14package labels 15 16import ( 17 "fmt" 18 "regexp" 19) 20 21// Selector holds constraints for matching against a label set. 22type Selector []Matcher 23 24// Matches returns whether the labels satisfy all matchers. 25func (s Selector) Matches(labels Labels) bool { 26 for _, m := range s { 27 if v := labels.Get(m.Name()); !m.Matches(v) { 28 return false 29 } 30 } 31 return true 32} 33 34// Matcher specifies a constraint for the value of a label. 35type Matcher interface { 36 // Name returns the label name the matcher should apply to. 37 Name() string 38 // Matches checks whether a value fulfills the constraints. 39 Matches(v string) bool 40 // String returns a human readable matcher. 41 String() string 42} 43 44// EqualMatcher matches on equality. 45type EqualMatcher struct { 46 name, value string 47} 48 49// Name implements Matcher interface. 50func (m EqualMatcher) Name() string { return m.name } 51 52// Matches implements Matcher interface. 53func (m EqualMatcher) Matches(v string) bool { return v == m.value } 54 55// String implements Matcher interface. 56func (m EqualMatcher) String() string { return fmt.Sprintf("%s=%q", m.name, m.value) } 57 58// Value returns the matched value. 59func (m EqualMatcher) Value() string { return m.value } 60 61// NewEqualMatcher returns a new matcher matching an exact label value. 62func NewEqualMatcher(name, value string) Matcher { 63 return &EqualMatcher{name: name, value: value} 64} 65 66type regexpMatcher struct { 67 name string 68 re *regexp.Regexp 69} 70 71func (m regexpMatcher) Name() string { return m.name } 72func (m regexpMatcher) Matches(v string) bool { return m.re.MatchString(v) } 73func (m regexpMatcher) String() string { return fmt.Sprintf("%s=~%q", m.name, m.re.String()) } 74 75// NewRegexpMatcher returns a new matcher verifying that a value matches 76// the regular expression pattern. 77func NewRegexpMatcher(name, pattern string) (Matcher, error) { 78 re, err := regexp.Compile(pattern) 79 if err != nil { 80 return nil, err 81 } 82 return ®expMatcher{name: name, re: re}, nil 83} 84 85// NewMustRegexpMatcher returns a new matcher verifying that a value matches 86// the regular expression pattern. Will panic if the pattern is not a valid 87// regular expression. 88func NewMustRegexpMatcher(name, pattern string) Matcher { 89 re, err := regexp.Compile(pattern) 90 if err != nil { 91 panic(err) 92 } 93 return ®expMatcher{name: name, re: re} 94 95} 96 97// NotMatcher inverts the matching result for a matcher. 98type NotMatcher struct { 99 Matcher 100} 101 102func (m NotMatcher) Matches(v string) bool { return !m.Matcher.Matches(v) } 103func (m NotMatcher) String() string { return fmt.Sprintf("not(%s)", m.Matcher.String()) } 104 105// Not inverts the matcher's matching result. 106func Not(m Matcher) Matcher { 107 return &NotMatcher{m} 108} 109