| 348 | } // namespace |
| 349 | |
| 350 | bool AstRewrite(Expr& expr, AstRewriter& visitor, |
| 351 | RewriteTraversalOptions options) { |
| 352 | std::stack<StackRecord> stack; |
| 353 | std::vector<const Expr*> traversal_path; |
| 354 | |
| 355 | stack.push(StackRecord(&expr)); |
| 356 | bool rewritten = false; |
| 357 | |
| 358 | while (!stack.empty()) { |
| 359 | StackRecord& record = stack.top(); |
| 360 | if (!record.visited) { |
| 361 | if (record.IsExprRecord()) { |
| 362 | traversal_path.push_back(record.expr()); |
| 363 | visitor.TraversalStackUpdate(absl::MakeSpan(traversal_path)); |
| 364 | |
| 365 | if (visitor.PreVisitRewrite(*record.expr())) { |
| 366 | rewritten = true; |
| 367 | } |
| 368 | } |
| 369 | PreVisit(record, &visitor); |
| 370 | PushDependencies(record, stack, options); |
| 371 | record.visited = true; |
| 372 | } else { |
| 373 | PostVisit(record, &visitor); |
| 374 | if (record.IsExprRecord()) { |
| 375 | if (visitor.PostVisitRewrite(*record.expr())) { |
| 376 | rewritten = true; |
| 377 | } |
| 378 | |
| 379 | traversal_path.pop_back(); |
| 380 | visitor.TraversalStackUpdate(absl::MakeSpan(traversal_path)); |
| 381 | } |
| 382 | stack.pop(); |
| 383 | } |
| 384 | } |
| 385 | |
| 386 | return rewritten; |
| 387 | } |
| 388 | |
| 389 | } // namespace cel |