add sum function (#32)

README.md

@@ -53,7 +53,7 @@ func main() {
 You can download `ajson` cli from the [release page](https://github.com/spyzhov/ajson/releases), or install from the source:
 
 ```shell script
-go get github.com/spyzhov/ajson/cmd/[email protected].0
+go get github.com/spyzhov/ajson/cmd/[email protected].1
 ```
 
 Usage:
@@ -327,6 +327,7 @@ Package has several predefined functions.
     roundtoeven  math.RoundToEven  integers, floats
     sin          math.Sin          integers, floats
     sinh         math.Sinh         integers, floats
+    sum          Sum               array of integers or floats
     sqrt         math.Sqrt         integers, floats
     tan          math.Tan          integers, floats
     tanh         math.Tanh         integers, floats

cmd/ajson/main.go

@@ -12,7 +12,7 @@ import (
 	"github.com/spyzhov/ajson"
 )
 
-var version = "v0.4.0"
+var version = "v0.4.1"
 
 func usage() {
 	text := ``

math.go

@@ -373,6 +373,24 @@ var (
 			}
 			return valueNode(nil, "avg", Null, nil), nil
 		},
+		"sum": func(node *Node) (result *Node, err error) {
+			if node.isContainer() {
+				sum := float64(0)
+				if node.Size() == 0 {
+					return valueNode(nil, "sum", Numeric, sum), nil
+				}
+				var value float64
+				for _, temp := range node.Inheritors() {
+					value, err = temp.GetNumeric()
+					if err != nil {
+						return nil, err
+					}
+					sum += value
+				}
+				return valueNode(nil, "sum", Numeric, sum), nil
+			}
+			return valueNode(nil, "sum", Null, nil), nil
+		},
 		"not": func(node *Node) (result *Node, err error) {
 			if value, err := boolean(node); err != nil {
 				return nil, err

math_test.go

@@ -395,6 +395,7 @@ func TestFunctions2(t *testing.T) {
 		{name: "length numeric", fname: "length", value: NumericNode("", 123), result: NumericNode("", 1)},
 		{name: "length bool", fname: "length", value: BoolNode("", false), result: NumericNode("", 1)},
 		{name: "length null", fname: "length", value: NullNode(""), result: NumericNode("", 1)},
+
 		{name: "avg error 1", fname: "avg", value: ArrayNode("test", []*Node{
 			valueNode(nil, "", Numeric, "foo"),
 			valueNode(nil, "", Numeric, "foo"),
@@ -418,6 +419,30 @@ func TestFunctions2(t *testing.T) {
 			"e": NumericNode("", 3),
 		}), result: NumericNode("", 2)},
 		{name: "avg array blank", fname: "avg", value: ArrayNode("test", []*Node{}), result: NumericNode("", 0)},
+
+		{name: "sum error 1", fname: "sum", value: ArrayNode("test", []*Node{
+			valueNode(nil, "", Numeric, "foo"),
+			valueNode(nil, "", Numeric, "foo"),
+			valueNode(nil, "", Numeric, "foo"),
+		}), fail: true},
+		{name: "sum error 2", fname: "sum", value: _e, fail: false, result: NullNode("")},
+		{name: "sum array 1", fname: "sum", value: ArrayNode("test", []*Node{
+			NumericNode("", 1),
+			NumericNode("", 1),
+			NumericNode("", 1),
+			NumericNode("", 1),
+		}), result: NumericNode("", 4)},
+		{name: "sum array 2", fname: "sum", value: ArrayNode("test", []*Node{
+			NumericNode("", 1),
+			NumericNode("", 2),
+			NumericNode("", 3),
+		}), result: NumericNode("", 6)},
+		{name: "sum object", fname: "sum", value: ObjectNode("test", map[string]*Node{
+			"q": NumericNode("", 1),
+			"w": NumericNode("", 2),
+			"e": NumericNode("", 3),
+		}), result: NumericNode("", 6)},
+		{name: "sum array blank", fname: "sum", value: ArrayNode("test", []*Node{}), result: NumericNode("", 0)},
 	}
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {