Implement switch statement, without the "complex switch statement" (aka switch statement with conti…

pkg/compiler/lib/src/ssa/switch_handler.dart

Index: pkg/compiler/lib/src/ssa/switch_handler.dart
diff --git a/pkg/compiler/lib/src/ssa/switch_handler.dart b/pkg/compiler/lib/src/ssa/switch_handler.dart
new file mode 100644
index 0000000000000000000000000000000000000000..8583cda6cbbd2a6e580d7b7386fb605e1bfade58
--- /dev/null
+++ b/pkg/compiler/lib/src/ssa/switch_handler.dart
@@ -0,0 +1,78 @@
+import 'package:kernel/ast.dart' as ir;
+
+/// Helper class that traverses a kernel AST subtree to see if it has any
+/// continue statements in the body of any switch cases (having continue
+/// statements results in a more complex generated code).
+class ContinueVisitor extends ir.Visitor {

[sra1, 2017/01/14 03:18:22]

Perhaps call is something more specific, e.g. SwitchContinueAnalysis
Name the file the 'same'.

[Emily Fortuna, 2017/01/17 23:33:09]

Done.

+  bool containsContinue;
+
+  ContinueVisitor(ir.Statement switchCaseBody) {
+    containsContinue = false;
+    switchCaseBody.accept(this);
+  }

[sra1, 2017/01/14 03:18:23]

If there are new statements, will this do the right thing, or should the default
be overridden to throw?

[Emily Fortuna, 2017/01/17 23:33:09]

Done.

+
+  void visitContinueSwitchStatement(ir.ContinueSwitchStatement continueStmt) {
+    containsContinue = true;

[sra1, 2017/01/14 03:18:23]

Do we want to know if it targets a specific switch (think of nested switch
statements, which one has the continue?)

[Emily Fortuna, 2017/01/17 23:33:09]

added TODO

+  }
+
+  void visitBlock(ir.Block block) {
+    for (ir.Statement statement in block.statements) {
+      statement.accept(this);
+    }
+  }
+
+  void visitLabeledStatement(ir.LabeledStatement statement) {
+    statement.body.accept(this);
+  }
+
+  void visitDoStatement(ir.DoStatement doStatement) {
+    doStatement.body.accept(this);
+  }
+
+  void visitForStatement(ir.ForStatement forStatement) {
+    forStatement.body.accept(this);
+  }
+
+  void visitForInStatement(ir.ForInStatement forInStatement) {
+    forInStatement.body.accept(this);
+  }
+
+  void visitSwitchStatement(ir.SwitchStatement switchStatement) {
+    for (var switchCase in switchStatement.cases) {
+      switchCase.accept(this);
+    }
+  }
+
+  void visitSwitchCase(ir.SwitchCase switchCase) {
+    switchCase.body.accept(this);
+  }
+
+  void visitIfStatement(ir.IfStatement ifStatement) {
+    ifStatement.then.accept(this);
+    ifStatement.otherwise?.accept(this);
+  }
+
+  void visitTryCatch(ir.TryCatch tryCatch) {
+    tryCatch.body.accept(this);
+    for (var catchStatement in tryCatch.catches) {
+      catchStatement.accept(this);
+    }
+  }
+
+  void visitCatch(ir.Catch catchStatement) {
+    catchStatement.body.accept(this);
+  }
+
+  void visitTryFinally(ir.TryFinally tryFinally) {
+    tryFinally.body.accept(this);
+    tryFinally.finalizer.accept(this);
+  }
+
+  void visitFunctionDeclaration(ir.FunctionDeclaration declaration) {
+    declaration.function.accept(this);
+  }
+
+  void visitFunctionNode(ir.FunctionNode node) {
+    node.body.accept(this);
+  }
+}