[ddc] Improve readability of if statement visit
As suggested in review
https://dart-review.googlesource.com/c/sdk/+/243363
Change-Id: Ib169def607e2461d7dc26a67590bb2e8a8a226da
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/294261
Commit-Queue: Nicholas Shahan <nshahan@google.com>
Reviewed-by: Mark Zhou <markzipan@google.com>
diff --git a/pkg/dev_compiler/lib/src/kernel/compiler.dart b/pkg/dev_compiler/lib/src/kernel/compiler.dart
index 4b503fe..607a998 100644
--- a/pkg/dev_compiler/lib/src/kernel/compiler.dart
+++ b/pkg/dev_compiler/lib/src/kernel/compiler.dart
@@ -4744,33 +4744,22 @@
@override
js_ast.Statement visitIfStatement(IfStatement node) {
+ bool isTriviallyTrue(condition) =>
+ condition is js_ast.LiteralBool && condition.value;
+
+ bool isTriviallyFalse(condition) =>
+ condition is js_ast.LiteralBool && !condition.value;
+
var condition = _visitTest(node.condition);
- if (node.otherwise != null) {
- if (condition is js_ast.LiteralBool) {
- // Avoid emitting the branch with code that will never execute.
- if (condition.value) {
- return _visitScope(node.then).toStatement();
- } else {
- return _visitScope(node.otherwise!).toStatement();
- }
- }
- return js_ast.If(
- condition, _visitScope(node.then), _visitScope(node.otherwise!));
+ if (isTriviallyTrue(condition)) return _visitScope(node.then);
+ var otherwise = node.otherwise;
+ var hasElse = otherwise != null;
+ if (isTriviallyFalse(condition)) {
+ return hasElse ? _visitScope(otherwise) : js_ast.EmptyStatement();
}
-
- if (condition is js_ast.LiteralBool) {
- if (condition.value) {
- // Avoid emitting conditional when it is always true.
- // ex: `if (true) {abc...}` -> `{abc...}`
- return _visitScope(node.then).toStatement();
- } else {
- // Avoid emitting conditional and then when it will never execute.
- // ex: `if (false) {abc...}` -> `;`
- return js_ast.EmptyStatement();
- }
- }
-
- return js_ast.If.noElse(condition, _visitScope(node.then));
+ return hasElse
+ ? js_ast.If(condition, _visitScope(node.then), _visitScope(otherwise))
+ : js_ast.If.noElse(condition, _visitScope(node.then));
}
/// Visits a statement, and ensures the resulting AST handles block scope
