prometheus/pkg/textparse/lex.l

%{
// Copyright 2017 The Prometheus 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 textparse

import (
        "fmt"
        "math"
        "strconv"
        "unicode/utf8"

        "github.com/prometheus/prometheus/pkg/value"
)

const (
    lstateInit = iota
    lstateName
    lstateValue
    lstateTimestamp
    lstateLabels
    lstateLName
    lstateLValue
    lstateLValueIn
)

// Lex is called by the parser generated by "go tool yacc" to obtain each
// token. The method is opened before the matching rules block and closed at
// the end of the file.
func (l *lexer) Lex() int {
    l.state = lstateInit

    if l.i >= len(l.b) {
        return eof
    }
    c := l.b[l.i]

    l.ts = nil
    l.mstart = l.nextMstart
    l.offsets = l.offsets[:0]
%}

D     [0-9]
L     [a-zA-Z_]
M     [a-zA-Z_:]

%x lstateName lstateValue lstateTimestamp lstateLabels lstateLName lstateLValue lstateLValueIn


%yyc c
%yyn c = l.next()
%yyt l.state


%%

\0                                    return eof
#[^\r\n]*\n                           l.mstart = l.i
[\r\n \t]+                            l.mstart = l.i

{M}({M}|{D})*                         l.state = lstateName
                                      l.offsets = append(l.offsets, l.i)
                                      l.mend = l.i

<lstateName>([ \t]*)\{                l.state = lstateLabels

<lstateName>[ \t]+                    l.state = lstateValue
                                      l.vstart = l.i


<lstateLabels>[ \t]+
<lstateLabels>,?\}                    l.state = lstateValue
                                      l.mend = l.i
<lstateLabels>(,?[ \t]*)              l.state = lstateLName
                                      l.offsets = append(l.offsets, l.i)

<lstateLName>{L}({L}|{D})*            l.offsets = append(l.offsets, l.i)
<lstateLName>[ \t]*=                  l.state = lstateLValue

<lstateLValue>[ \t]+
<lstateLValue>\"                      l.state = lstateLValueIn
                                      l.offsets = append(l.offsets, l.i)
<lstateLValueIn>(\\.|[^\\"])*\"       l.state = lstateLabels
                                      if !utf8.Valid(l.b[l.offsets[len(l.offsets)-1]:l.i-1]) {
                                        l.err = fmt.Errorf("invalid UTF-8 label value")
                                        return -1
                                      }
                                      l.offsets = append(l.offsets, l.i-1)

<lstateValue>[ \t]+                   l.vstart = l.i
<lstateValue>(NaN)                    l.val = math.Float64frombits(value.NormalNaN)
                                      l.state = lstateTimestamp

<lstateValue>[^\n \t\r]+              // We don't parse strictly correct floats as the conversion
                                      // repeats the effort anyway.
                                      l.val, l.err = strconv.ParseFloat(yoloString(l.b[l.vstart:l.i]), 64)
                                      if l.err != nil {
                                          return -1
                                      }
                                      l.state = lstateTimestamp

<lstateTimestamp>[ \t]+               l.tstart = l.i
<lstateTimestamp>{D}+                 ts, err := strconv.ParseInt(yoloString(l.b[l.tstart:l.i]), 10, 64)
                                      if err != nil {
                                          l.err = err
                                          return -1
                                      }
                                      l.ts = &ts
<lstateTimestamp>[\r\n]+              l.nextMstart = l.i
                                      return 1
<lstateTimestamp>\0                   return 1

%%
    l.err = fmt.Errorf("no token found")
    return -1
}