Test and fix more JS generation

avp · facebook-github-bot · commit b36023fe7a37 · 2021-09-02T13:10:36.000-07:00
Reviewed By: tmikov

Differential Revision: D30438835

fbshipit-source-id: 27ad500f722088c9912b3f5995a1e36fbca1de99
diff --git a/unsupported/juno/src/gen_js.rs b/unsupported/juno/src/gen_js.rs
@@ -2661,6 +2661,8 @@ impl<W: Write> GenJS<W> {
     /// which is situated at `child_pos` position in relation to its `parent`.
     fn need_parens(&self, parent: &Node, child: &Node, child_pos: ChildPos) -> NeedParens {
         use NodeKind::*;
+
+        #[allow(clippy::if_same_then_else)]
         if matches!(parent.kind, ArrowFunctionExpression { .. }) {
             // (x) => ({x: 10}) needs parens to avoid confusing it with a block and a
             // labelled statement.
@@ -2689,10 +2691,10 @@ impl<W: Write> GenJS<W> {
             || (is_unary_op(parent, UnaryExpressionOperator::Plus)
                 && self.root_starts_with(child, check_plus))
             || (child_pos == ChildPos::Right
-                && is_binary_op(parent, "-")
+                && is_binary_op(parent, BinaryExpressionOperator::Minus)
                 && self.root_starts_with(child, check_minus))
             || (child_pos == ChildPos::Right
-                && is_binary_op(parent, "+")
+                && is_binary_op(parent, BinaryExpressionOperator::Plus)
                 && self.root_starts_with(child, check_plus))
         {
             // -(-x) or -(--x) or -(-5)
@@ -2715,6 +2717,12 @@ impl<W: Write> GenJS<W> {
             // we need the left hand side to be parenthesized.
             // Avoids confusing `(a?.b).c` with `a?.b.c`.
             return NeedParens::Yes;
+        } else if (check_and_or(parent) && check_nullish(child))
+            || (check_nullish(parent) && check_and_or(child))
+        {
+            // Nullish coalescing always requires parens when mixed with any
+            // other logical operations.
+            return NeedParens::Yes;
         }
 
         let (child_prec, _child_assoc) = self.get_precedence(child);
@@ -2826,9 +2834,9 @@ fn is_negative_number(node: &Node) -> bool {
     }
 }
 
-fn is_binary_op(node: &Node, op: &str) -> bool {
+fn is_binary_op(node: &Node, op: BinaryExpressionOperator) -> bool {
     match &node.kind {
-        NodeKind::BinaryExpression { operator, .. } => operator.as_str() == op,
+        NodeKind::BinaryExpression { operator, .. } => *operator == op,
         _ => false,
     }
 }
@@ -2850,6 +2858,26 @@ fn check_minus(node: &Node) -> bool {
         || is_update_prefix(node, UpdateExpressionOperator::Decrement)
 }
 
+fn check_and_or(node: &Node) -> bool {
+    matches!(
+        &node.kind,
+        NodeKind::LogicalExpression {
+            operator: LogicalExpressionOperator::And | LogicalExpressionOperator::Or,
+            ..
+        }
+    )
+}
+
+fn check_nullish(node: &Node) -> bool {
+    matches!(
+        &node.kind,
+        NodeKind::LogicalExpression {
+            operator: LogicalExpressionOperator::NullishCoalesce,
+            ..
+        }
+    )
+}
+
 fn ends_with_block(node: Option<&Node>) -> bool {
     use NodeKind::*;
     match node {
diff --git a/unsupported/juno/tests/gen_js.rs b/unsupported/juno/tests/gen_js.rs
@@ -89,6 +89,12 @@ fn test_literals() {
     test_roundtrip("/abc/gi");
 }
 
+#[test]
+fn test_identifier() {
+    test_roundtrip("foo");
+    test_roundtrip("class C { #foo() {} }");
+}
+
 #[test]
 fn test_binop() {
     use NodeKind::*;
@@ -108,6 +114,17 @@ fn test_binop() {
     test_roundtrip("1 + 1");
     test_roundtrip("1 * 2 + (3 + 4)");
     test_roundtrip("1 ** 2 ** 3 ** 4");
+    test_roundtrip("1 in 2 + (2 - 4) / 3");
+    test_roundtrip("1 instanceof 2 + (2 - 4) / 3");
+}
+
+#[test]
+fn test_conditional() {
+    test_roundtrip("a ? b : c");
+    test_roundtrip("a ? b : c ? d : e");
+    test_roundtrip("(a ? b : c) ? d : e");
+    test_roundtrip("a ? b : (c ? d : e)");
+    test_roundtrip("a?.3:.4");
 }
 
 #[test]
@@ -122,6 +139,7 @@ fn test_functions() {
     test_roundtrip("function foo(x, y) {}");
     test_roundtrip("function foo(x, y=3) {}");
     test_roundtrip("function foo([x, y], {z}) {}");
+    test_roundtrip("function foo([x, y] = [1,2], {z:q}) {}");
     test_roundtrip("function foo() { return this; }");
     test_roundtrip("function *foo() {}");
     test_roundtrip("function *foo() { yield 1; }");
@@ -215,6 +233,15 @@ fn test_statements() {
     test_roundtrip("if (x) fn(); else fn();");
 }
 
+#[test]
+fn test_logical() {
+    test_roundtrip("a && b || c");
+    test_roundtrip("a || b && c");
+    test_roundtrip("(a || b) && c");
+    test_roundtrip("(a || b) ?? c");
+    test_roundtrip("(a ?? b) || c");
+}
+
 #[test]
 fn test_sequences() {
     test_roundtrip("var x = (1, 2, 3);");
@@ -296,6 +323,38 @@ fn test_members() {
     test_roundtrip("(a?.b?.c?.())?.d");
     test_roundtrip("(a?.b?.c?.())(d)");
     test_roundtrip("(a?.b?.c?.())?.(d)");
+    test_roundtrip("class C { constructor() { new.target; } }");
+}
+
+#[test]
+fn test_classes() {
+    test_roundtrip("class C {}");
+    test_roundtrip("class C extends D {}");
+    test_roundtrip(
+        "class C extends D {
+            prop1;
+            #prop2;
+            constructor() {}
+            a() {}
+            #b() {}
+            c(x, y) {}
+            static d() {}
+        }",
+    );
+    test_roundtrip(
+        "var cls = (class C extends D {
+            prop1;
+            #prop2;
+            constructor() {}
+            a() {}
+            #b() {}
+            c(x, y) {}
+            static d() {}
+            get e() {}
+            set e(v) {}
+            ;
+        })",
+    );
 }
 
 #[test]
