mirror of https://github.com/k3s-io/k3s
124 lines
2.9 KiB
Go
124 lines
2.9 KiB
Go
/*
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Copyright 2014 Google Inc. All rights reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package labels
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import (
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"fmt"
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"strings"
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)
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// Represents a label query.
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type Query interface {
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// Returns true if this query matches the given set of labels.
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Matches(Labels) bool
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// Prints a human readable version of this label query.
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String() string
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}
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// Everything returns a query that matches all labels.
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func Everything() Query {
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return andTerm{}
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}
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type hasTerm struct {
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label, value string
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}
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func (t *hasTerm) Matches(ls Labels) bool {
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return ls.Get(t.label) == t.value
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}
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func (t *hasTerm) String() string {
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return fmt.Sprintf("%v=%v", t.label, t.value)
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}
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type notHasTerm struct {
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label, value string
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}
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func (t *notHasTerm) Matches(ls Labels) bool {
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return ls.Get(t.label) != t.value
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}
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func (t *notHasTerm) String() string {
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return fmt.Sprintf("%v!=%v", t.label, t.value)
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}
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type andTerm []Query
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func (t andTerm) Matches(ls Labels) bool {
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for _, q := range t {
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if !q.Matches(ls) {
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return false
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}
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}
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return true
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}
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func (t andTerm) String() string {
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var terms []string
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for _, q := range t {
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terms = append(terms, q.String())
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}
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return strings.Join(terms, ",")
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}
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func try(queryPiece, op string) (lhs, rhs string, ok bool) {
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pieces := strings.Split(queryPiece, op)
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if len(pieces) == 2 {
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return pieces[0], pieces[1], true
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}
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return "", "", false
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}
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// Given a Set, return a Query which will match exactly that Set.
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func QueryFromSet(ls Set) Query {
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var items []Query
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for label, value := range ls {
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items = append(items, &hasTerm{label: label, value: value})
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}
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if len(items) == 1 {
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return items[0]
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}
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return andTerm(items)
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}
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// Takes a string repsenting a label query and returns an object suitable for matching, or an error.
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func ParseQuery(query string) (Query, error) {
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parts := strings.Split(query, ",")
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var items []Query
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for _, part := range parts {
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if part == "" {
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continue
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}
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if lhs, rhs, ok := try(part, "!="); ok {
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items = append(items, ¬HasTerm{label: lhs, value: rhs})
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} else if lhs, rhs, ok := try(part, "=="); ok {
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items = append(items, &hasTerm{label: lhs, value: rhs})
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} else if lhs, rhs, ok := try(part, "="); ok {
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items = append(items, &hasTerm{label: lhs, value: rhs})
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} else {
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return nil, fmt.Errorf("invalid label query: '%s'; can't understand '%s'", query, part)
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}
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}
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if len(items) == 1 {
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return items[0], nil
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}
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return andTerm(items), nil
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}
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