upgrade to xpression v0.9.0

expression.go

@@ -62,23 +62,29 @@ func findClosingBracket(path []byte, i int) (int, error) {
 
 // filterMatch evaluates previously parsed expression and returns boolean to filter out array elements
 func filterMatch(input []byte, toks []*xpression.Token) (bool, error) {
-	varFunc := func(str []byte) (*xpression.Operand, error) {
+	varFunc := func(str []byte, result *xpression.Operand) error {
+		if str[0] == '$' {
+			// root-based reference has already been evaluated at start
+			return nil
+		}
 		if str[0] != '@' {
-			return xpression.Undefined(), nil
+			// we only handle item-based references
+			result.SetUndefined()
+			return nil
 		}
 		str[0] = '$'
 		defer func() { str[0] = '@' }()
 		val, err := Get(input, string(str))
 		if val == nil || err != nil {
 			// not found or other error
-			return xpression.Undefined(), nil
+			result.SetUndefined()
+			return err
 		}
-		op := &xpression.Operand{}
-		err = decodeValue(val, op)
+		err = decodeValue(val, result)
 		if err != nil {
-			return xpression.Undefined(), nil
+			result.SetUndefined()
 		}
-		return op, nil
+		return err
 	}
 
 	op, err := xpression.Evaluate(toks, varFunc)

go.mod

@@ -2,4 +2,4 @@ module github.com/bhmj/jsonslice
 
 go 1.17
 
-require github.com/bhmj/xpression v0.8.0
+require github.com/bhmj/xpression v0.9.0

go.sum

@@ -1,2 +1,2 @@
-github.com/bhmj/xpression v0.8.0 h1:3qO6TLbFNOblQGMoSnf0QlXSZ1PwLTCCXTE6Yy4B+sA=
-github.com/bhmj/xpression v0.8.0/go.mod h1:j9oYmEXJjeL9mrgW1+ZDBKJXnbupsCPGhlO9J5YhS1Q=
+github.com/bhmj/xpression v0.9.0 h1:fptQyWeYLUybLW3BnSGBnBvjZPdR0/j/SwFVrfenZLo=
+github.com/bhmj/xpression v0.9.0/go.mod h1:j9oYmEXJjeL9mrgW1+ZDBKJXnbupsCPGhlO9J5YhS1Q=

jsonslice.go

@@ -138,15 +138,17 @@ func Get(input []byte, path string) ([]byte, error) {
 			break
 		}
 		if n.Filter != nil {
-			for _, tok := range n.Filter {
+			for i, tok := range n.Filter {
 				if tok.Type == xpression.VariableOperand && tok.Operand.Str[0] == '$' {
+					// every variable has an empty token right after it for storing the result
+					result := n.Filter[i+1] 
+					// evaluate root-based reference
 					val, err := Get(input, string(tok.Operand.Str))
 					if err != nil {
 						// not found or other error
-						tok.Type = xpression.UndefinedOperand
+						result.Type = xpression.UndefinedOperand
 					}
-					_ = decodeValue(val, &tok.Operand)
-					xpression.SetLiteral(tok)
+					_ = decodeValue(val, &result.Operand)
 				}
 			}
 		}