2 files changed, 133 insertions, 0 deletions
diff --git a/funcs/math.go b/funcs/math.go
new file mode 100644
index 00000000..e26e42dc
--- /dev/null
+++ b/funcs/math.go
@@ -0,0 +1,72 @@
+package funcs
+
+import (
+	"fmt"
+	gmath "math"
+	"sync"
+
+	"github.com/hairyhenderson/gomplate/conv"
+
+	"github.com/hairyhenderson/gomplate/math"
+)
+
+var (
+	mathNS     *MathFuncs
+	mathNSInit sync.Once
+)
+
+// MathNS - the math namespace
+func MathNS() *MathFuncs {
+	mathNSInit.Do(func() { mathNS = &MathFuncs{} })
+	return mathNS
+}
+
+// AddMathFuncs -
+func AddMathFuncs(f map[string]interface{}) {
+	f["math"] = MathNS
+
+	f["add"] = MathNS().Add
+	f["sub"] = MathNS().Sub
+	f["mul"] = MathNS().Mul
+	f["div"] = MathNS().Div
+	f["rem"] = MathNS().Rem
+	f["pow"] = MathNS().Pow
+}
+
+// MathFuncs -
+type MathFuncs struct{}
+
+// Add -
+func (f *MathFuncs) Add(n ...interface{}) int64 {
+	return math.AddInt(conv.ToInt64s(n...)...)
+}
+
+// Mul -
+func (f *MathFuncs) Mul(n ...interface{}) int64 {
+	return math.MulInt(conv.ToInt64s(n...)...)
+}
+
+// Sub -
+func (f *MathFuncs) Sub(a, b interface{}) int64 {
+	return conv.ToInt64(a) - conv.ToInt64(b)
+}
+
+// Div -
+func (f *MathFuncs) Div(a, b interface{}) (int64, error) {
+	divisor := conv.ToInt64(a)
+	dividend := conv.ToInt64(b)
+	if dividend == 0 {
+		return 0, fmt.Errorf("Error: division by 0")
+	}
+	return divisor / dividend, nil
+}
+
+// Rem -
+func (f *MathFuncs) Rem(a, b interface{}) int64 {
+	return conv.ToInt64(a) % conv.ToInt64(b)
+}
+
+// Pow -
+func (f *MathFuncs) Pow(a, b interface{}) int64 {
+	return conv.ToInt64(gmath.Pow(conv.ToFloat64(a), conv.ToFloat64(b)))
+}
diff --git a/funcs/math_test.go b/funcs/math_test.go
new file mode 100644
index 00000000..cb0a0922
--- /dev/null
+++ b/funcs/math_test.go
@@ -0,0 +1,61 @@
+package funcs
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAdd(t *testing.T) {
+	m := MathNS()
+	assert.Equal(t, int64(12), m.Add(1, 1, 2, 3, 5))
+	assert.Equal(t, int64(2), m.Add(1, 1))
+	assert.Equal(t, int64(1), m.Add(1))
+	assert.Equal(t, int64(0), m.Add(-5, 5))
+}
+
+func TestMul(t *testing.T) {
+	m := MathNS()
+	assert.Equal(t, int64(30), m.Mul(1, 1, 2, 3, 5))
+	assert.Equal(t, int64(1), m.Mul(1, 1))
+	assert.Equal(t, int64(1), m.Mul(1))
+	assert.Equal(t, int64(-25), m.Mul("-5", 5))
+	assert.Equal(t, int64(28), m.Mul(14, "2"))
+}
+
+func TestSub(t *testing.T) {
+	m := MathNS()
+	assert.Equal(t, int64(0), m.Sub(1, 1))
+	assert.Equal(t, int64(-10), m.Sub(-5, 5))
+	assert.Equal(t, int64(-41), m.Sub(true, "42"))
+}
+
+func mustDiv(a, b interface{}) int64 {
+	m := MathNS()
+	r, err := m.Div(a, b)
+	if err != nil {
+		return -1
+	}
+	return r
+}
+
+func TestDiv(t *testing.T) {
+	m := MathNS()
+	_, err := m.Div(1, 0)
+	assert.Error(t, err)
+	assert.Equal(t, int64(1), mustDiv(1, 1))
+	assert.Equal(t, int64(-1), mustDiv(-5, 5))
+	assert.Equal(t, int64(0), mustDiv(true, "42"))
+}
+
+func TestRem(t *testing.T) {
+	m := MathNS()
+	assert.Equal(t, int64(0), m.Rem(1, 1))
+	assert.Equal(t, int64(2), m.Rem(5, 3.0))
+	// assert.Equal(t, int64(1), m.Mod(true, "42"))
+}
+
+func TestPow(t *testing.T) {
+	m := MathNS()
+	assert.Equal(t, int64(4), m.Pow(2, "2"))
+}