PromQL: add short string method

To be used in tracing or logging.

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>

promql/parser/printer.go

@@ -72,6 +72,11 @@ func (node *AggregateExpr) String() string {
 	return aggrString
 }
 
+func (node *AggregateExpr) ShortString() string {
+	aggrString := node.getAggOpStr()
+	return aggrString
+}
+
 func (node *AggregateExpr) getAggOpStr() string {
 	aggrString := node.Op.String()
 
@@ -95,14 +100,20 @@ func joinLabels(ss []string) string {
 	return strings.Join(ss, ", ")
 }
 
-func (node *BinaryExpr) String() string {
-	returnBool := ""
+func (node *BinaryExpr) returnBool() string {
 	if node.ReturnBool {
-		returnBool = " bool"
+		return " bool"
 	}
+	return ""
+}
 
+func (node *BinaryExpr) String() string {
 	matching := node.getMatchingStr()
-	return fmt.Sprintf("%s %s%s%s %s", node.LHS, node.Op, returnBool, matching, node.RHS)
+	return fmt.Sprintf("%s %s%s%s %s", node.LHS, node.Op, node.returnBool(), matching, node.RHS)
+}
+
+func (node *BinaryExpr) ShortString() string {
+	return fmt.Sprintf("%s%s%s", node.Op, node.returnBool(), node.getMatchingStr())
 }
 
 func (node *BinaryExpr) getMatchingStr() string {
@@ -130,9 +141,13 @@ func (node *Call) String() string {
 	return fmt.Sprintf("%s(%s)", node.Func.Name, node.Args)
 }
 
-func (node *MatrixSelector) String() string {
+func (node *Call) ShortString() string {
+	return node.Func.Name
+}
+
+func (node *MatrixSelector) atOffset() (string, string) {
 	// Copy the Vector selector before changing the offset
-	vecSelector := *node.VectorSelector.(*VectorSelector)
+	vecSelector := node.VectorSelector.(*VectorSelector)
 	offset := ""
 	switch {
 	case vecSelector.OriginalOffset > time.Duration(0):
@@ -149,7 +164,13 @@ func (node *MatrixSelector) String() string {
 	case vecSelector.StartOrEnd == END:
 		at = " @ end()"
 	}
+	return at, offset
+}
 
+func (node *MatrixSelector) String() string {
+	at, offset := node.atOffset()
+	// Copy the Vector selector before changing the offset
+	vecSelector := *node.VectorSelector.(*VectorSelector)
 	// Do not print the @ and offset twice.
 	offsetVal, atVal, preproc := vecSelector.OriginalOffset, vecSelector.Timestamp, vecSelector.StartOrEnd
 	vecSelector.OriginalOffset = 0
@@ -163,10 +184,19 @@ func (node *MatrixSelector) String() string {
 	return str
 }
 
+func (node *MatrixSelector) ShortString() string {
+	at, offset := node.atOffset()
+	return fmt.Sprintf("[%s]%s%s", model.Duration(node.Range), at, offset)
+}
+
 func (node *SubqueryExpr) String() string {
 	return fmt.Sprintf("%s%s", node.Expr.String(), node.getSubqueryTimeSuffix())
 }
 
+func (node *SubqueryExpr) ShortString() string {
+	return node.getSubqueryTimeSuffix()
+}
+
 // getSubqueryTimeSuffix returns the '[<range>:<step>] @ <timestamp> offset <offset>' suffix of the subquery.
 func (node *SubqueryExpr) getSubqueryTimeSuffix() string {
 	step := ""
@@ -208,6 +238,10 @@ func (node *UnaryExpr) String() string {
 	return fmt.Sprintf("%s%s", node.Op, node.Expr)
 }
 
+func (node *UnaryExpr) ShortString() string {
+	return node.Op.String()
+}
+
 func (node *VectorSelector) String() string {
 	var labelStrings []string
 	if len(node.LabelMatchers) > 1 {