Add time series description parsing.

This commit adds parsing of time series description to the exisiting
query language parser. Time series descriptions are defined by a
metric followed by a sequence of values.

promql/lex.go

@@ -284,6 +284,10 @@ type lexer struct {
 	braceOpen   bool // Whether a { is opened.
 	bracketOpen bool // Whether a [ is opened.
 	stringOpen  rune // Quote rune of the string currently being read.
+
+	// seriesDesc is set when a series description for the testing
+	// language is lexed.
+	seriesDesc bool
 }
 
 // next returns the next rune in the input.
@@ -536,6 +540,10 @@ func lexInsideBraces(l *lexer) stateFn {
 	case r == '}':
 		l.emit(itemRightBrace)
 		l.braceOpen = false
+
+		if l.seriesDesc {
+			return lexValueSequence
+		}
 		return lexStatements
 	default:
 		return l.errorf("unexpected character inside braces: %q", r)
@@ -670,7 +678,7 @@ func (l *lexer) scanNumber() bool {
 		l.acceptRun("0123456789")
 	}
 	// Next thing must not be alphanumeric.
-	if isAlphaNumeric(l.peek()) {
+	if isAlphaNumeric(l.peek()) && !l.seriesDesc {
 		return false
 	}
 	return true
@@ -709,6 +717,9 @@ Loop:
 			break Loop
 		}
 	}
+	if l.seriesDesc && l.peek() != '{' {
+		return lexValueSequence
+	}
 	return lexStatements
 }
 

promql/lex_test.go

@@ -23,6 +23,7 @@ var tests = []struct {
 	input      string
 	expected   []item
 	fail       bool
+	seriesDesc bool // Whether to lex a series description.
 }{
 	// Test common stuff.
 	{
@@ -398,6 +399,7 @@ var tests = []struct {
 func TestLexer(t *testing.T) {
 	for i, test := range tests {
 		l := lex(test.input)
+		l.seriesDesc = test.seriesDesc
 
 		out := []item{}
 		for it := range l.items {

promql/parse.go

@@ -70,6 +70,14 @@ func ParseExpr(input string) (Expr, error) {
 	return expr, err
 }
 
+// parseSeriesDesc parses the description of a time series.
+func parseSeriesDesc(input string) (clientmodel.Metric, []sequenceValue, error) {
+	p := newParser(input)
+	p.lex.seriesDesc = true
+
+	return p.parseSeriesDesc()
+}
+
 // newParser returns a new parser.
 func newParser(input string) *parser {
 	p := &parser{
@@ -112,6 +120,105 @@ func (p *parser) parseExpr() (expr Expr, err error) {
 	return
 }
 
+// sequenceValue is a omittable value in a sequence of time series values.
+type sequenceValue struct {
+	value   clientmodel.SampleValue
+	omitted bool
+}
+
+func (v sequenceValue) String() string {
+	if v.omitted {
+		return "_"
+	}
+	return v.value.String()
+}
+
+// parseSeriesDesc parses a description of a time series into its metric and value sequence.
+func (p *parser) parseSeriesDesc() (m clientmodel.Metric, vals []sequenceValue, err error) {
+	defer p.recover(&err)
+
+	name := ""
+	m = clientmodel.Metric{}
+
+	t := p.peek().typ
+	if t == itemIdentifier || t == itemMetricIdentifier {
+		name = p.next().val
+		t = p.peek().typ
+	}
+	if t == itemLeftBrace {
+		m = clientmodel.Metric(p.labelSet())
+	}
+	if name != "" {
+		m[clientmodel.MetricNameLabel] = clientmodel.LabelValue(name)
+	}
+
+	const ctx = "series values"
+	for {
+		if p.peek().typ == itemEOF {
+			break
+		}
+
+		// Extract blanks.
+		if p.peek().typ == itemBlank {
+			p.next()
+			times := uint64(1)
+			if p.peek().typ == itemTimes {
+				p.next()
+				times, err = strconv.ParseUint(p.expect(itemNumber, ctx).val, 10, 64)
+				if err != nil {
+					p.errorf("invalid repetition in %s: %s", ctx, err)
+				}
+			}
+			for i := uint64(0); i < times; i++ {
+				vals = append(vals, sequenceValue{omitted: true})
+			}
+			continue
+		}
+
+		// Extract values.
+		sign := 1.0
+		if t := p.peek().typ; t == itemSUB || t == itemADD {
+			if p.next().typ == itemSUB {
+				sign = -1
+			}
+		}
+		k := sign * p.number(p.expect(itemNumber, ctx).val)
+		vals = append(vals, sequenceValue{
+			value: clientmodel.SampleValue(k),
+		})
+
+		// If there are no offset repetitions specified, proceed with the next value.
+		if t := p.peek().typ; t == itemNumber || t == itemBlank {
+			continue
+		} else if t == itemEOF {
+			break
+		} else if t != itemADD && t != itemSUB {
+			p.errorf("expected next value or relative expansion in %s but got %s", ctx, t.desc())
+		}
+
+		// Expand the repeated offsets into values.
+		sign = 1.0
+		if p.next().typ == itemSUB {
+			sign = -1.0
+		}
+		offset := sign * p.number(p.expect(itemNumber, ctx).val)
+		p.expect(itemTimes, ctx)
+
+		times, err := strconv.ParseUint(p.expect(itemNumber, ctx).val, 10, 64)
+		if err != nil {
+			p.errorf("invalid repetition in %s: %s", ctx, err)
+		}
+
+		for i := uint64(0); i < times; i++ {
+			k += offset
+			vals = append(vals, sequenceValue{
+				value: clientmodel.SampleValue(k),
+			})
+		}
+	}
+	return m, vals, nil
+}
+
 // typecheck checks correct typing of the parsed statements or expression.
 func (p *parser) typecheck(node Node) (err error) {
 	defer p.recover(&err)

promql/parse_test.go

@@ -1216,3 +1216,101 @@ func mustGetFunction(name string) *Function {
 	}
 	return f
 }
+
+var testSeries = []struct {
+	input          string
+	expectedMetric clientmodel.Metric
+	expectedValues []sequenceValue
+	fail           bool
+}{
+	{
+		input:          `{} 1 2 3`,
+		expectedMetric: clientmodel.Metric{},
+		expectedValues: newSeq(1, 2, 3),
+	}, {
+		input: `{a="b"} -1 2 3`,
+		expectedMetric: clientmodel.Metric{
+			"a": "b",
+		},
+		expectedValues: newSeq(-1, 2, 3),
+	}, {
+		input: `my_metric 1 2 3`,
+		expectedMetric: clientmodel.Metric{
+			clientmodel.MetricNameLabel: "my_metric",
+		},
+		expectedValues: newSeq(1, 2, 3),
+	}, {
+		input: `my_metric{} 1 2 3`,
+		expectedMetric: clientmodel.Metric{
+			clientmodel.MetricNameLabel: "my_metric",
+		},
+		expectedValues: newSeq(1, 2, 3),
+	}, {
+		input: `my_metric{a="b"} 1 2 3`,
+		expectedMetric: clientmodel.Metric{
+			clientmodel.MetricNameLabel: "my_metric",
+			"a": "b",
+		},
+		expectedValues: newSeq(1, 2, 3),
+	}, {
+		input: `my_metric{a="b"} 1 2 3-10x4`,
+		expectedMetric: clientmodel.Metric{
+			clientmodel.MetricNameLabel: "my_metric",
+			"a": "b",
+		},
+		expectedValues: newSeq(1, 2, 3, -7, -17, -27, -37),
+	}, {
+		input: `my_metric{a="b"} 1 3 _ 5 _x4`,
+		expectedMetric: clientmodel.Metric{
+			clientmodel.MetricNameLabel: "my_metric",
+			"a": "b",
+		},
+		expectedValues: newSeq(1, 3, none, 5, none, none, none, none),
+	}, {
+		input: `my_metric{a="b"} 1 3 _ 5 _a4`,
+		fail:  true,
+	},
+}
+
+// For these tests only, we use the samallest float64 to signal an omitted value.
+const none = math.SmallestNonzeroFloat64
+
+func newSeq(vals ...float64) (res []sequenceValue) {
+	for _, v := range vals {
+		if v == none {
+			res = append(res, sequenceValue{omitted: true})
+		} else {
+			res = append(res, sequenceValue{value: clientmodel.SampleValue(v)})
+		}
+	}
+	return res
+}
+
+func TestParseSeries(t *testing.T) {
+	for _, test := range testSeries {
+		parser := newParser(test.input)
+		parser.lex.seriesDesc = true
+
+		metric, vals, err := parser.parseSeriesDesc()
+		if !test.fail && err != nil {
+			t.Errorf("error in input: \n\n%s\n", test.input)
+			t.Fatalf("could not parse: %s", err)
+		}
+		if test.fail && err != nil {
+			continue
+		}
+
+		if test.fail {
+			if err != nil {
+				continue
+			}
+			t.Errorf("error in input: \n\n%s\n", test.input)
+			t.Fatalf("failure expected, but passed")
+		}
+
+		if !reflect.DeepEqual(vals, test.expectedValues) || !reflect.DeepEqual(metric, test.expectedMetric) {
+			t.Errorf("error in input: \n\n%s\n", test.input)
+			t.Fatalf("no match\n\nexpected:\n%s %s\ngot: \n%s %s\n", test.expectedMetric, test.expectedValues, metric, vals)
+		}
+	}
+}