From 7ed399c1e3ea2d944bcb558dcd252b8bfccef606 Mon Sep 17 00:00:00 2001
From: Sven Rebhan <sven.rebhan@googlemail.com>
Date: Fri, 24 Sep 2021 00:00:01 +0200
Subject: [PATCH 1/2] Make all floating-point functions return NaN if arguments
 could not be converted to a number.

---
 func.go | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/func.go b/func.go
index fd4187b..afe5988 100644
--- a/func.go
+++ b/func.go
@@ -122,17 +122,19 @@ func asNumber(t iterator, o interface{}) float64 {
 		return typ
 	case string:
 		v, err := strconv.ParseFloat(typ, 64)
-		if err != nil {
-			panic(errors.New("ceiling() function argument type must be a node-set or number"))
+		if err == nil {
+			return v
 		}
-		return v
 	}
-	return 0
+	return math.NaN()
 }
 
 // ceilingFunc is a XPath Node Set functions ceiling(node-set).
 func ceilingFunc(q query, t iterator) interface{} {
 	val := asNumber(t, functionArgs(q).Evaluate(t))
+	// if math.IsNaN(val) {
+	// 	panic(errors.New("ceiling() function argument type must be a valid number"))
+	// }
 	return math.Ceil(val)
 }
 

From d9cc617a6088a9b091b58f37aaefabddc266fbf5 Mon Sep 17 00:00:00 2001
From: Sven Rebhan <sven.rebhan@googlemail.com>
Date: Fri, 24 Sep 2021 00:00:09 +0200
Subject: [PATCH 2/2] Formatting.

---
 func_go110.go     | 3 ++-
 func_pre_go110.go | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/func_go110.go b/func_go110.go
index 6df30d3..a515ac1 100644
--- a/func_go110.go
+++ b/func_go110.go
@@ -1,3 +1,4 @@
+//go:build go1.10
 // +build go1.10
 
 package xpath
@@ -11,6 +12,6 @@ func round(f float64) int {
 	return int(math.Round(f))
 }
 
-func newStringBuilder() stringBuilder{ 
+func newStringBuilder() stringBuilder {
 	return &strings.Builder{}
 }
diff --git a/func_pre_go110.go b/func_pre_go110.go
index 335141f..a1497f2 100644
--- a/func_pre_go110.go
+++ b/func_pre_go110.go
@@ -1,3 +1,4 @@
+//go:build !go1.10
 // +build !go1.10
 
 package xpath