metrics-server/vendor/k8s.io/gengo/types/comments.go

/*
Copyright 2015 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

// Package types contains go type information, packaged in a way that makes
// auto-generation convenient, whether by template or straight go functions.
package types

import (
	"fmt"
	"strings"
)

// ExtractCommentTags parses comments for lines of the form:
//
//   'marker' + "key=value".
//
// Values are optional; "" is the default.  A tag can be specified more than
// one time and all values are returned.  If the resulting map has an entry for
// a key, the value (a slice) is guaranteed to have at least 1 element.
//
// Example: if you pass "+" for 'marker', and the following lines are in
// the comments:
//   +foo=value1
//   +bar
//   +foo=value2
//   +baz="qux"
// Then this function will return:
//   map[string][]string{"foo":{"value1, "value2"}, "bar": {""}, "baz": {"qux"}}
func ExtractCommentTags(marker string, lines []string) map[string][]string {
	out := map[string][]string{}
	for _, line := range lines {
		line = strings.Trim(line, " ")
		if len(line) == 0 {
			continue
		}
		if !strings.HasPrefix(line, marker) {
			continue
		}
		// TODO: we could support multiple values per key if we split on spaces
		kv := strings.SplitN(line[len(marker):], "=", 2)
		if len(kv) == 2 {
			out[kv[0]] = append(out[kv[0]], kv[1])
		} else if len(kv) == 1 {
			out[kv[0]] = append(out[kv[0]], "")
		}
	}
	return out
}

// ExtractSingleBoolCommentTag parses comments for lines of the form:
//
//   'marker' + "key=value1"
//
// If the tag is not found, the default value is returned.  Values are asserted
// to be boolean ("true" or "false"), and any other value will cause an error
// to be returned.  If the key has multiple values, the first one will be used.
func ExtractSingleBoolCommentTag(marker string, key string, defaultVal bool, lines []string) (bool, error) {
	values := ExtractCommentTags(marker, lines)[key]
	if values == nil {
		return defaultVal, nil
	}
	if values[0] == "true" {
		return true, nil
	}
	if values[0] == "false" {
		return false, nil
	}
	return false, fmt.Errorf("tag value for %q is not boolean: %q", key, values[0])
}