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

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

+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 SwitchContinueAnalysis extends ir.Visitor<bool> {
+
+  SwitchContinueAnalysis._();
+
+  static bool containsContinue(ir.Statement switchCaseBody) {
+    return switchCaseBody.accept(new SwitchContinueAnalysis._());
+  }
+
+  bool visitContinueSwitchStatement(ir.ContinueSwitchStatement continueStmt) {
+    // TODO(efortuna): Check what the target of this continue statement actually
+    // IS, because depending on where the label points if we have a nested
+    // switch statement we might be able to output simpler code (not the complex
+    // switch statement).
+    return true;
+  }
+
+  bool visitBlock(ir.Block block) {
+    for (ir.Statement statement in block.statements) {
+      if (statement.accept(this)) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  bool visitLabeledStatement(ir.LabeledStatement statement) {
+    return statement.body.accept(this);
+  }
+
+  bool visitDoStatement(ir.DoStatement doStatement) {
+    return doStatement.body.accept(this);
+  }
+
+  bool visitForStatement(ir.ForStatement forStatement) {
+    return forStatement.body.accept(this);
+  }
+
+  bool visitForInStatement(ir.ForInStatement forInStatement) {
+    return forInStatement.body.accept(this);
+  }
+
+  bool visitSwitchStatement(ir.SwitchStatement switchStatement) {
+    for (var switchCase in switchStatement.cases) {
+      if (switchCase.accept(this)) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  bool visitSwitchCase(ir.SwitchCase switchCase) {
+    return switchCase.body.accept(this);
+  }
+
+  bool visitIfStatement(ir.IfStatement ifStatement) {
+    if (ifStatement.then.accept(this)) {
+      if (ifStatement.otherwise != null) {
+        return ifStatement.otherwise.accept(this);
+      }
+    }
+    return false;
+  }
+
+  bool visitTryCatch(ir.TryCatch tryCatch) {
+    if (tryCatch.body.accept(this)) {
+      for (var catchStatement in tryCatch.catches) {
+        if (catchStatement.accept(this)) {
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+
+  bool visitWhileStatement(ir.WhileStatement statement) {
+    return statement.body.accept(this);
+  }
+
+  bool visitCatch(ir.Catch catchStatement) {
+    return catchStatement.body.accept(this);
+  }
+
+  bool visitTryFinally(ir.TryFinally tryFinally) {
+    return tryFinally.body.accept(this) &&
+        tryFinally.finalizer.accept(this);
+  }
+
+  bool visitFunctionDeclaration(ir.FunctionDeclaration declaration) {
+    return declaration.function.accept(this);
+  }
+
+  bool visitFunctionNode(ir.FunctionNode node) {
+    return node.body.accept(this);
+  }
+
+  bool defaultStatement(ir.Statement node) {
+    if (node is ir.ExpressionStatement || node is ir.EmptyStatement ||
+        node is ir.InvalidStatement || node is ir.BreakStatement ||
+        node is ir.ReturnStatement || node is ir.AssertStatement ||
+        node is ir.YieldStatement || node is ir.VariableDeclaration) {
+      return false;
+    }
+    throw 'Statement type ${node.runtimeType} not handled in '
+        'SwitchContinueAnalysis';
+  }
+
+  bool defaultNode(ir.Node node) => false;
+}