mirror of https://github.com/knative/caching.git
78 lines
2.2 KiB
Go
78 lines
2.2 KiB
Go
/*
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Copyright 2021 The Knative Authors
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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 kmap
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// KeyPriority is a utility struct for getting values from a map
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// given a list of ordered keys
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//
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// This is to help the migration/renaming of annotations & labels
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type KeyPriority []string
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// Key returns the default key that should be used for
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// accessing the map
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func (p KeyPriority) Key() string {
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// this intentionally panics rather than returning an empty string
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return p[0]
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}
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// Value iterates looks up the ordered keys in the map and returns
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// a string value. An empty string will be returned if the keys
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// are not present in the map
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func (p KeyPriority) Value(m map[string]string) string {
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_, v, _ := p.Get(m)
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return v
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}
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// Get iterates over the ordered keys and looks up the corresponding
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// values in the map
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//
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// It returns the key, value, and true|false signaling whether the
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// key was present in the map
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//
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// If no key is present the default key (lowest ordinal) is returned
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// with an empty string as the value
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func (p KeyPriority) Get(m map[string]string) (string, string, bool) {
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var k, v string
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var ok bool
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for _, k = range p {
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v, ok = m[k]
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if ok {
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return k, v, ok
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}
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}
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return p.Key(), "", false
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}
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// UpdateKey will update the map with the KeyPriority's default
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// key iff any of the other synonym keys are present
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func (p KeyPriority) UpdateKey(m map[string]string) {
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if k, v, ok := p.Get(m); ok && k != p.Key() {
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delete(m, k)
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m[p.Key()] = v
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}
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}
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// UpdateKeys iterates over the lookups and updates entries in the map
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// to use the default key
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func UpdateKeys(m map[string]string, keys ...KeyPriority) map[string]string {
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for _, key := range keys {
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key.UpdateKey(m)
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}
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return m
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}
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