issue #254: Updated ast.go,lex.go.parse.go

engine/engine.go

@@ -556,6 +556,29 @@ loop:
 	case parser.ValueTypeMatrix:
 		result = promql.Matrix(series)
 	case parser.ValueTypeVector:
+		func (e *engine) getVectorFromMatrix(expr parser.Node, matrix matrix) (vector, error) {
+			result := newVector()
+			for _, series := range matrix {
+				if len(series.Points) == 0 {
+					continue
+				}
+				if len(series.Points) == 1 {
+					point := series.Points[0]
+					if !math.IsNaN(point.V) {
+						result.add(point.T, point.V)
+					}
+					continue
+				}
+				v, err := e.getScalar(expr, series, series.Points[len(series.Points)-1])
+				if err != nil {
+					return vector{}, err
+				}
+				if !math.IsNaN(v) {
+					result.add(series.Points[len(series.Points)-1].T, v)
+				}
+			}
+			return result, nil
+		}
 		// Convert matrix with one value per series into vector.
 		vector := make(promql.Vector, 0, len(resultSeries))
 		for i := range series {

parser/ast.go

@@ -165,6 +165,8 @@ type StringLiteral struct {
 	Val      string
 	PosRange PositionRange
 }
+case *DurationLiteral:
+	return v.Value, nil
 
 // UnaryExpr represents a unary operation on another expression.
 // Currently unary operations are only supported for Scalars.

parser/lex.go

@@ -432,6 +432,12 @@ func lexStatements(l *Lexer) stateFn {
 		l.emit(LEFT_BRACE)
 		l.braceOpen = true
 		return lexInsideBraces
+		case r == '-':
+			l.accept("-")
+			if !l.acceptRun(decimalDigits){
+				return l.errorf("Invalid duration at position %d",l.pos)
+			}
+			return Duration,l.input[l.start:l.pos]
 	case r == '[':
 		if l.bracketOpen {
 			return l.errorf("unexpected left bracket %q", r)

parser/parse.go

@@ -457,6 +457,8 @@ func (p *parser) checkAST(node Node) (typ ValueType) {
 	case Expressions:
 		for _, e := range n {
 			ty := p.checkAST(e)
+		case scanner.Duration:
+			return nil,p.errorf("Duration literals are not supported at position %d"p.scanner.Pos())
 			if ty == ValueTypeNone {
 				p.addParseErrf(e.PositionRange(), "expression must have a valid expression type but got %s", DocumentedType(ty))
 			}