mirror of
https://github.com/prometheus/statsd_exporter.git
synced 2024-11-26 09:11:01 +00:00
76 lines
2.4 KiB
Go
76 lines
2.4 KiB
Go
// Copyright 2018 The Prometheus 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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package fsm
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import (
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"fmt"
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"regexp"
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"strconv"
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"strings"
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)
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var (
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templateReplaceCaptureRE = regexp.MustCompile(`\$\{?([a-zA-Z0-9_\$]+)\}?`)
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)
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type TemplateFormatter struct {
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captureIndexes []int
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captureCount int
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fmtString string
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}
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// NewTemplateFormatter instantiates a TemplateFormatter
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// from given template string and the maximum amount of captures.
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func NewTemplateFormatter(template string, captureCount int) *TemplateFormatter {
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matches := templateReplaceCaptureRE.FindAllStringSubmatch(template, -1)
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if len(matches) == 0 {
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// if no regex reference found, keep it as it is
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return &TemplateFormatter{captureCount: 0, fmtString: template}
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}
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var indexes []int
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valueFormatter := template
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for _, match := range matches {
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idx, err := strconv.Atoi(match[len(match)-1])
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if err != nil || idx > captureCount || idx < 1 {
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// if index larger than captured count or using unsupported named capture group,
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// replace with empty string
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valueFormatter = strings.Replace(valueFormatter, match[0], "", -1)
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} else {
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valueFormatter = strings.Replace(valueFormatter, match[0], "%s", -1)
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// note: the regex reference variable $? starts from 1
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indexes = append(indexes, idx-1)
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}
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}
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return &TemplateFormatter{
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captureIndexes: indexes,
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captureCount: len(indexes),
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fmtString: valueFormatter,
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}
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}
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// Format accepts a list containing captured strings and returns the formatted
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// string using the template stored in current TemplateFormatter.
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func (formatter *TemplateFormatter) Format(captures []string) string {
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if formatter.captureCount == 0 {
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// no label substitution, keep as it is
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return formatter.fmtString
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}
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indexes := formatter.captureIndexes
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vargs := make([]interface{}, formatter.captureCount)
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for i, idx := range indexes {
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vargs[i] = captures[idx]
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}
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return fmt.Sprintf(formatter.fmtString, vargs...)
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}
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