fix(selection): handle multiple objects inner parenthesis

selection.go

@@ -1,6 +1,7 @@
 package jsonmask
 
 import (
+	"errors"
 	"fmt"
 	"strings"
 	"unicode/utf8"
@@ -32,7 +33,6 @@ func (s Selection) equal(other Selection) bool {
 // a(b,c)  sub-selection will select many fields from a parent
 // a/*/c   the star * wildcard will select all items in a field
 // a,b/c(d,e(f,g/h)),i
-//
 func Compile(str string) (Selection, error) {
 	if !utf8.ValidString(str) {
 		return nil, fmt.Errorf("invalid fields")
@@ -103,6 +103,7 @@ func Compile(str string) (Selection, error) {
 
 	node := make(Selection)
 	err := buildSelection(tokens, node)
+
 	return node, err
 }
 
@@ -120,7 +121,10 @@ func buildSelection(tokens []string, root Selection) error {
 		case "/":
 			node = child
 		case "(":
-			end := findCloseIndex(tokens, i+1)
+			end, err := findCloseIndex(tokens, i)
+			if err != nil {
+				return err
+			}
 			if end == -1 {
 				return fmt.Errorf("sub-selector not close")
 			}
@@ -138,11 +142,22 @@ func buildSelection(tokens []string, root Selection) error {
 	return nil
 }
 
-func findCloseIndex(tokens []string, start int) int {
-	for i := len(tokens) - 1; i >= start; i-- {
-		if tokens[i] == ")" {
-			return i
+func findCloseIndex(tokens []string, start int) (int, error) {
+	closeIdx := start
+	counter := 1
+	for {
+		if counter == 0 {
+			return closeIdx, nil
+		}
+		closeIdx++
+		if closeIdx > (len(tokens) - 1) {
+			return 0, errors.New("unbalanced parenthesis")
+		}
+		switch tokens[closeIdx] {
+		case "(":
+			counter++
+		case ")":
+			counter--
 		}
 	}
-	return -1
 }

selection_test.go

@@ -1,6 +1,9 @@
 package jsonmask
 
-import "testing"
+import (
+	"fmt"
+	"testing"
+)
 
 type selectionCase struct {
 	fields    string
@@ -133,19 +136,92 @@ var selectionCases = []selectionCase{
 			"i": Selection{},
 		},
 	},
+	{
+		fields:    "a,b/c(d(e,f),g(h,i/j)),k",
+		shouldErr: false,
+		res: Selection{
+			"a": Selection{},
+			"b": Selection{"c": Selection{
+				"d": Selection{
+					"e": Selection{},
+					"f": Selection{},
+				},
+				"g": Selection{
+					"h": Selection{},
+					"i": Selection{"j": Selection{}},
+				},
+			}},
+			"k": Selection{},
+		},
+	},
+	{
+		fields:    "a,b/c(d(e,f),g(h,i/j(k,l))),m",
+		shouldErr: false,
+		res: Selection{
+			"a": Selection{},
+			"b": Selection{
+				"c": Selection{
+					"d": Selection{
+						"e": Selection{},
+						"f": Selection{},
+					},
+					"g": Selection{
+						"h": Selection{},
+						"i": Selection{"j": Selection{
+							"k": Selection{},
+							"l": Selection{},
+						}},
+					},
+				},
+			},
+			"m": Selection{},
+		},
+	},
+	{
+		fields:    "a,b/c(d(e,f),g(h,i/j(k(l),m(n,o/p)))),q",
+		shouldErr: false,
+		res: Selection{
+			"a": Selection{},
+			"b": Selection{
+				"c": Selection{
+					"d": Selection{
+						"e": Selection{},
+						"f": Selection{},
+					},
+					"g": Selection{
+						"h": Selection{},
+						"i": Selection{"j": Selection{
+							"k": Selection{
+								"l": Selection{},
+							},
+							"m": Selection{
+								"n": Selection{},
+								"o": Selection{
+									"p": Selection{},
+								},
+							},
+						}},
+					},
+				},
+			},
+			"q": Selection{},
+		},
+	},
 }
 
 func TestCompile(t *testing.T) {
 	for _, c := range selectionCases {
-		res, err := Compile(c.fields)
-		if c.shouldErr {
-			if err == nil {
-				t.Errorf("Testing case[%s] failed: should error but got: %#v", c.fields, res)
+		t.Run(fmt.Sprint("fields=[", c.fields, "]"), func(t *testing.T) {
+			res, err := Compile(c.fields)
+			if c.shouldErr {
+				if err == nil {
+					t.Errorf("Testing case[%s] failed: should error but got: %#v", c.fields, res)
+				}
+			} else if err != nil {
+				t.Errorf("Testing case[%s] failed: %s", c.fields, err)
+			} else if !c.res.equal(res) {
+				t.Errorf("Testing case[%s] failed, expected: %#v, got: %#v", c.fields, c.res, res)
 			}
-		} else if err != nil {
-			t.Errorf("Testing case[%s] failed: %s", c.fields, err)
-		} else if !c.res.equal(res) {
-			t.Errorf("Testing case[%s] failed, expected: %#v, got: %#v", c.fields, c.res, res)
-		}
+		})
 	}
 }