Add math.Max and math.Min

Closes #8583

docs/content/en/functions/math.md

@@ -1,6 +1,6 @@
 ---
 title: Math
-description: Hugo provides nine mathematical operators in templates.
+description: Hugo provides mathematical operators in templates.
 godocref:
 date: 2017-02-01
 publishdate: 2017-02-01
@@ -35,7 +35,9 @@ aliases: []
 | `modBool`    | Boolean of modulus of two integers. Evaluates to `true` if result equals 0. | `{{modBool 15 3}}` → `true` |
 | `math.Ceil`  | Returns the least integer value greater than or equal to the given number.  | `{{math.Ceil 2.1}}` → `3`   |
 | `math.Floor` | Returns the greatest integer value less than or equal to the given number.  | `{{math.Floor 1.9}}` → `1`  |
-| `math.Round` | Returns the nearest integer, rounding half away from zero.                  | `{{math.Round 1.5}}` → `2`  |
 | `math.Log`   | Returns the natural logarithm of the given number.                          | `{{math.Log 42}}` → `3.737` |
-| `math.Sqrt`  | Returns the square root of the given number.                                | `{{math.Sqrt 81}}` → `9`    |
+| `math.Max`   | Returns the greater of two numbers.                                         | `{{math.Max 1 2}}` → `2`    |
+| `math.Min`   | Returns the smaller of two numbers.                                         | `{{math.Min 1 2}}` → `1`    |
 | `math.Pow`   | Returns the first number raised to the power of the second number.          | `{{math.Pow 2 3}}` → `8`    |
+| `math.Round` | Returns the nearest integer, rounding half away from zero.                  | `{{math.Round 1.5}}` → `2`  |
+| `math.Sqrt`  | Returns the square root of the given number.                                | `{{math.Sqrt 81}}` → `9`    |

tpl/math/init.go

@@ -64,10 +64,17 @@ func init() {
 			},
 		)
 
-		ns.AddMethodMapping(ctx.Sqrt,
+		ns.AddMethodMapping(ctx.Max,
 			nil,
 			[][2]string{
-				{"{{math.Sqrt 81}}", "9"},
+				{"{{math.Max 1 2 }}", "2"},
+			},
+		)
+
+		ns.AddMethodMapping(ctx.Min,
+			nil,
+			[][2]string{
+				{"{{math.Min 1 2 }}", "1"},
 			},
 		)
 
@@ -106,6 +113,13 @@ func init() {
 			},
 		)
 
+		ns.AddMethodMapping(ctx.Sqrt,
+			nil,
+			[][2]string{
+				{"{{math.Sqrt 81}}", "9"},
+			},
+		)
+
 		ns.AddMethodMapping(ctx.Sub,
 			[]string{"sub"},
 			[][2]string{

tpl/math/math.go

@@ -71,15 +71,28 @@ func (ns *Namespace) Log(a interface{}) (float64, error) {
 	return math.Log(af), nil
 }
 
-// Sqrt returns the square root of a number.
-// NOTE: will return for NaN for negative values of a
-func (ns *Namespace) Sqrt(a interface{}) (float64, error) {
-	af, err := cast.ToFloat64E(a)
-	if err != nil {
-		return 0, errors.New("Sqrt operator can't be used with non integer or float value")
+// Max returns the greater of two numbers.
+func (ns *Namespace) Max(a, b interface{}) (float64, error) {
+	af, erra := cast.ToFloat64E(a)
+	bf, errb := cast.ToFloat64E(b)
+
+	if erra != nil || errb != nil {
+		return 0, errors.New("Max operator can't be used with non-float value")
 	}
 
-	return math.Sqrt(af), nil
+	return math.Max(af, bf), nil
+}
+
+// Min returns the smaller of two numbers.
+func (ns *Namespace) Min(a, b interface{}) (float64, error) {
+	af, erra := cast.ToFloat64E(a)
+	bf, errb := cast.ToFloat64E(b)
+
+	if erra != nil || errb != nil {
+		return 0, errors.New("Min operator can't be used with non-float value")
+	}
+
+	return math.Min(af, bf), nil
 }
 
 // Mod returns a % b.
@@ -135,6 +148,16 @@ func (ns *Namespace) Round(x interface{}) (float64, error) {
 	return _round(xf), nil
 }
 
+// Sqrt returns the square root of a number.
+func (ns *Namespace) Sqrt(a interface{}) (float64, error) {
+	af, err := cast.ToFloat64E(a)
+	if err != nil {
+		return 0, errors.New("Sqrt operator can't be used with non integer or float value")
+	}
+
+	return math.Sqrt(af), nil
+}
+
 // Sub subtracts two numbers.
 func (ns *Namespace) Sub(a, b interface{}) (interface{}, error) {
 	return _math.DoArithmetic(a, b, '-')

tpl/math/math_test.go

@@ -357,3 +357,81 @@ func TestPow(t *testing.T) {
 		c.Assert(result, qt.Equals, test.expect)
 	}
 }
+
+func TestMax(t *testing.T) {
+	t.Parallel()
+	c := qt.New(t)
+
+	ns := New()
+
+	for _, test := range []struct {
+		a      interface{}
+		b      interface{}
+		expect interface{}
+	}{
+		{-1, -1, float64(-1)},
+		{-1, 0, float64(0)},
+		{-1, 1, float64(1)},
+		{0, -1, float64(0)},
+		{0, 0, float64(0)},
+		{0, 1, float64(1)},
+		{1, -1, float64(1)},
+		{1, 0, float64(1)},
+		{1, 1, float64(1)},
+		{1.2, 1.23, float64(1.23)},
+		{-1.2, -1.23, float64(-1.2)},
+		{0, "a", false},
+		{"a", 0, false},
+		{"a", "b", false},
+	} {
+
+		result, err := ns.Max(test.a, test.b)
+
+		if b, ok := test.expect.(bool); ok && !b {
+			c.Assert(err, qt.Not(qt.IsNil))
+			continue
+		}
+
+		c.Assert(err, qt.IsNil)
+		c.Assert(result, qt.Equals, test.expect)
+	}
+}
+
+func TestMin(t *testing.T) {
+	t.Parallel()
+	c := qt.New(t)
+
+	ns := New()
+
+	for _, test := range []struct {
+		a      interface{}
+		b      interface{}
+		expect interface{}
+	}{
+		{-1, -1, float64(-1)},
+		{-1, 0, float64(-1)},
+		{-1, 1, float64(-1)},
+		{0, -1, float64(-1)},
+		{0, 0, float64(0)},
+		{0, 1, float64(0)},
+		{1, -1, float64(-1)},
+		{1, 0, float64(0)},
+		{1, 1, float64(1)},
+		{1.2, 1.23, float64(1.2)},
+		{-1.2, -1.23, float64(-1.23)},
+		{0, "a", false},
+		{"a", 0, false},
+		{"a", "b", false},
+	} {
+
+		result, err := ns.Min(test.a, test.b)
+
+		if b, ok := test.expect.(bool); ok && !b {
+			c.Assert(err, qt.Not(qt.IsNil))
+			continue
+		}
+
+		c.Assert(err, qt.IsNil)
+		c.Assert(result, qt.Equals, test.expect)
+	}
+}