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fix: fix unary and binary node print
consider the precedence of operators and their associative law when printing unary and binary nodes
  • Loading branch information
zhuliquan committed Jun 26, 2024
commit 33757149daa05feaeb8734b831081211785e6c86
25 changes: 23 additions & 2 deletions ast/print.go
Original file line number Diff line number Diff line change
Expand Up @@ -50,8 +50,13 @@ func (n *UnaryNode) String() string {
op = fmt.Sprintf("%s ", n.Operator)
}
wrap := false
switch n.Node.(type) {
case *BinaryNode, *ConditionalNode:
switch b := n.Node.(type) {
case *BinaryNode:
if operator.Binary[b.Operator].Precedence <
operator.Unary[n.Operator].Precedence {
wrap = true
}
case *ConditionalNode:
wrap = true
}
if wrap {
Expand All @@ -68,10 +73,21 @@ func (n *BinaryNode) String() string {
var lhs, rhs string
var lwrap, rwrap bool

if l, ok := n.Left.(*UnaryNode); ok {
if operator.Unary[l.Operator].Precedence <
operator.Binary[n.Operator].Precedence {
lwrap = true
}
}
if lb, ok := n.Left.(*BinaryNode); ok {
if operator.Less(lb.Operator, n.Operator) {
lwrap = true
}
if operator.Binary[lb.Operator].Precedence ==
operator.Binary[n.Operator].Precedence &&
operator.Binary[n.Operator].Associativity == operator.Right {
lwrap = true
}
if lb.Operator == "??" {
lwrap = true
}
Expand All @@ -83,6 +99,11 @@ func (n *BinaryNode) String() string {
if operator.Less(rb.Operator, n.Operator) {
rwrap = true
}
if operator.Binary[rb.Operator].Precedence ==
operator.Binary[n.Operator].Precedence &&
operator.Binary[n.Operator].Associativity == operator.Left {
rwrap = true
}
if operator.IsBoolean(rb.Operator) && n.Operator != rb.Operator {
rwrap = true
}
Expand Down
5 changes: 5 additions & 0 deletions ast/print_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -78,6 +78,11 @@ func TestPrint(t *testing.T) {
{`{("a" + "b"): 42}`, `{("a" + "b"): 42}`},
{`(One == 1 ? true : false) && Two == 2`, `(One == 1 ? true : false) && Two == 2`},
{`not (a == 1 ? b > 1 : b < 2)`, `not (a == 1 ? b > 1 : b < 2)`},
{`(-(1+1)) ** 2`, `(-(1 + 1)) ** 2`},
{`2 ** (-(1+1))`, `2 ** -(1 + 1)`},
{`(2 ** 2) ** 3`, `(2 ** 2) ** 3`},
{`(3 + 5) / (5 % 3)`, `(3 + 5) / (5 % 3)`},
{`(-(1+1)) == 2`, `-(1 + 1) == 2`},
}

for _, tt := range tests {
Expand Down