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regexp.go
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regexp.go
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// Copyright 2015-2018 trivago N.V.
//
// 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 format
import (
"github.com/trivago/gollum/core"
"regexp"
)
// RegExp formatter
//
// This formatter parses a message using a regular expression, performs
// string (template) replacement and returns the result.
//
// Parameters
//
// - Posix: Set to true to compile the regular expression using posix semantics.
// By default this parameter is set to true.
//
// - Expression: Defines the regular expression used for parsing.
// For details on the regexp syntax see https://golang.org/pkg/regexp/syntax.
// By default this parameter is set to "(.*)"
//
// - Template: Defines the result string. Regexp matching groups can be referred
// to using "${n}", with n being the group's index. For other possible
// reference semantics, see https://golang.org/pkg/regexp/#Regexp.Expand.
// By default this parameter is set to "${1}"
//
// Examples
//
// This example extracts time and host from an imaginary log message format.
//
// exampleConsumer:
// Type: consumer.Console
// Streams: stding
// Modulators:
// - format.RegExp:
// Expression: "^(\\d+) (\\w+): "
// Template: "time: ${1}, host: ${2}"
type RegExp struct {
core.SimpleFormatter `gollumdoc:"embed_type"`
expression *regexp.Regexp
template []byte `config:"Template" default:"${1}"`
}
func init() {
core.TypeRegistry.Register(RegExp{})
}
// Configure initializes this formatter with values from a plugin config.
func (format *RegExp) Configure(conf core.PluginConfigReader) {
var err error
if conf.GetBool("Posix", true) {
format.expression, err = regexp.CompilePOSIX(conf.GetString("Expression", "(.*)"))
} else {
format.expression, err = regexp.Compile(conf.GetString("Expression", "(.*)"))
}
conf.Errors.Push(err)
}
// ApplyFormatter update message payload
func (format *RegExp) ApplyFormatter(msg *core.Message) error {
content := format.GetAppliedContent(msg)
matches := format.expression.FindSubmatchIndex(content)
transformed := format.expression.Expand([]byte{}, format.template, content, matches)
format.SetAppliedContent(msg, transformed)
return nil
}