Method startLabelName

expfmt/text_parse.go:337–443

startLabelName represents the state where the next byte read from p.buf is the start of a label name (or whitespace leading up to it).

()

// startLabelName represents the state where the next byte read from p.buf is
// the start of a label name (or whitespace leading up to it).
func (p *TextParser) startLabelName() stateFn {
	if p.skipBlankTab(); p.err != nil {
		return nil // Unexpected end of input.
	}
	if p.currentByte == '}' {
		if p.currentMF == nil {
			// The closing brace was reached before any metric name was read,
			// e.g. for the input "{}". There is no metric to attach labels to,
			// so this is a malformed exposition. This mirrors the guard in
			// startLabelValue. currentMF (not currentMetric) is checked because
			// reset only clears currentMF between parses.
			p.parseError("invalid metric name")
			p.currentLabelPairs = nil
			return nil
		}
		p.currentMetric.Label = append(p.currentMetric.Label, p.currentLabelPairs...)
		p.currentLabelPairs = nil
		if p.skipBlankTab(); p.err != nil {
			return nil // Unexpected end of input.
		}
		return p.readingValue
	}
	if p.readTokenAsLabelName(); p.err != nil {
		return nil // Unexpected end of input.
	}
	if p.currentToken.Len() == 0 {
		p.parseError(fmt.Sprintf("invalid label name for metric %q", p.currentMF.GetName()))
		return nil
	}
	if p.skipBlankTabIfCurrentBlankTab(); p.err != nil {
		return nil // Unexpected end of input.
	}
	if p.currentByte != '=' {
		if p.currentMetricIsInsideBraces {
			if p.currentMetricInsideBracesIsPresent {
				p.parseError(fmt.Sprintf("multiple metric names for metric %q", p.currentMF.GetName()))
				return nil
			}
			switch p.currentByte {
			case ',':
				p.setOrCreateCurrentMF()
				if p.err != nil {
					return nil
				}
				if p.currentMF.Type == nil {
					p.currentMF.Type = dto.MetricType_UNTYPED.Enum()
				}
				p.currentMetric = &dto.Metric{}
				p.currentMetricInsideBracesIsPresent = true
				return p.startLabelName
			case '}':
				p.setOrCreateCurrentMF()
				if p.err != nil {
					p.currentLabelPairs = nil
					return nil
				}
				if p.currentMF.Type == nil {
					p.currentMF.Type = dto.MetricType_UNTYPED.Enum()