prometheus/pkg/textparse/lex.l

%{
package textparse

import (
        "fmt"
        "math"
        "strconv"
)

//type lstate int


// 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 {
    const (
        lstateInit = iota
        lstateValue
        lstateLabels
        lstateLName
        lstateLValue
    )
    s := lstateInit
    
    if l.i >= len(l.b) {
        return eof
    }
    c := l.b[l.i]

    l.offsets = l.offsets[:0]
%}

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

%x lstateValue lstateLabels lstateLName lstateLValue


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


%%

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

{L}({L}|{D})*\{      s = lstateLabels
                     l.offsets = append(l.offsets, l.i-1)
{L}({L}|{D})*        s = lstateValue
                     l.mend = l.i
                     l.offsets = append(l.offsets, l.i)

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

<lstateLName>{M}({M}|{D})*=    s = lstateLValue
                               l.offsets = append(l.offsets, l.i-1)

<lstateLValue>\"(\\.|[^\\"])*\"       s = lstateLabels
                                      l.offsets = append(l.offsets, l.i-1)
<lstateLValue>\'(\\.|[^\\'])*\'       s = lstateLabels
                                      l.offsets = append(l.offsets, l.i-1)

<lstateValue>[ \t]+             l.vstart = l.i
<lstateValue>(NaN)              l.val = math.NaN()
                                return 1
<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
                                }
                                return 1
   
%%
    return -1
}