Add math.Round polyfill for pre1.10 (#41)

.travis.yml

@@ -8,6 +8,7 @@ go:
   - '1.11'
   - '1.12'
   - '1.13'
+  - '1.14'
   - 'tip'
 
 os:

twig/filter/filter.go

@@ -2,16 +2,17 @@
 package filter // import "github.com/tyler-sommer/stick/twig/filter"
 
 import (
-  "encoding/json"
+	"encoding/json"
 	"fmt"
 	"math"
 	"sort"
 	"strings"
 	"unicode/utf8"
 
-	"github.com/tyler-sommer/stick"
 	"reflect"
 	"time"
+
+	"github.com/tyler-sommer/stick"
 )
 
 // builtInFilters returns a map containing all built-in Twig filters,
@@ -417,7 +418,7 @@ func filterRound(ctx stick.Context, val stick.Value, args ...stick.Value) stick.
 	precision := 0
 	algo := ""
 	if len(args) > 0 {
-		precision = int(math.Round(stick.CoerceNumber(args[0])))
+		precision = int(mathRound(stick.CoerceNumber(args[0])))
 	}
 	if precision < 0 {
 		precision = 0
@@ -433,7 +434,7 @@ func filterRound(ctx stick.Context, val stick.Value, args ...stick.Value) stick.
 	case "floor":
 		return math.Floor(input*mult) / mult
 	default:
-		return math.Round(input*mult) / mult
+		return mathRound(input*mult) / mult
 	}
 }
 

twig/filter/filter_test.go

@@ -3,9 +3,10 @@ package filter
 import (
 	"testing"
 
-	"github.com/tyler-sommer/stick"
 	"strings"
 	"time"
+
+	"github.com/tyler-sommer/stick"
 )
 
 func TestFilters(t *testing.T) {
@@ -93,8 +94,8 @@ func TestFilters(t *testing.T) {
 				return filterReplace(nil, "I like %this% and %that%.", map[string]string{"%this%": "foo", "%that%": "bar"})
 			},
 			"I like foo and bar.",
-    },
-    {
+		},
+		{
 			"json encode",
 			func() stick.Value {
 				return filterJSONEncode(nil, map[string]interface{}{"a": 1, "b": true, "c": 3.14, "d": "a string", "e": []string{"one", "two"}, "f": map[string]interface{}{"alpha": "foo", "beta": nil}})

twig/filter/round_go1.10.go

@@ -0,0 +1,11 @@
+// +build go1.10
+
+package filter
+
+import (
+	"math"
+)
+
+func mathRound(f float64) float64 {
+	return math.Round(f)
+}

twig/filter/round_pre1.10.go

@@ -0,0 +1,15 @@
+// +build !go1.10
+
+package filter
+
+import (
+	"math"
+)
+
+func mathRound(x float64) float64 {
+	t := math.Trunc(x)
+	if math.Abs(x-t) >= 0.5 {
+		return t + math.Copysign(1, x)
+	}
+	return t
+}