| // Copyright 2021 The Tint Authors. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #ifndef SRC_TINT_AST_TRAVERSE_EXPRESSIONS_H_ |
| #define SRC_TINT_AST_TRAVERSE_EXPRESSIONS_H_ |
| |
| #include <vector> |
| |
| #include "src/tint/ast/binary_expression.h" |
| #include "src/tint/ast/bitcast_expression.h" |
| #include "src/tint/ast/call_expression.h" |
| #include "src/tint/ast/index_accessor_expression.h" |
| #include "src/tint/ast/literal_expression.h" |
| #include "src/tint/ast/member_accessor_expression.h" |
| #include "src/tint/ast/phony_expression.h" |
| #include "src/tint/ast/unary_op_expression.h" |
| #include "src/tint/utils/reverse.h" |
| #include "src/tint/utils/vector.h" |
| |
| namespace tint::ast { |
| |
| /// The action to perform after calling the TraverseExpressions() callback |
| /// function. |
| enum class TraverseAction { |
| /// Stop traversal immediately. |
| Stop, |
| /// Descend into this expression. |
| Descend, |
| /// Do not descend into this expression. |
| Skip, |
| }; |
| |
| /// The order TraverseExpressions() will traverse expressions |
| enum class TraverseOrder { |
| /// Expressions will be traversed from left to right |
| LeftToRight, |
| /// Expressions will be traversed from right to left |
| RightToLeft, |
| }; |
| |
| /// TraverseExpressions performs a depth-first traversal of the expression nodes |
| /// from `root`, calling `callback` for each of the visited expressions that |
| /// match the predicate parameter type, in pre-ordering (root first). |
| /// @param root the root expression node |
| /// @param diags the diagnostics used for error messages |
| /// @param callback the callback function. Must be of the signature: |
| /// `TraverseAction(const T* expr)` or `TraverseAction(const T* expr, size_t depth)` where T |
| /// is an ast::Expression type. |
| /// @return true on success, false on error |
| template <TraverseOrder ORDER = TraverseOrder::LeftToRight, typename CALLBACK> |
| bool TraverseExpressions(const ast::Expression* root, diag::List& diags, CALLBACK&& callback) { |
| using EXPR_TYPE = std::remove_pointer_t<traits::ParameterType<CALLBACK, 0>>; |
| constexpr static bool kHasDepthArg = traits::SignatureOfT<CALLBACK>::parameter_count == 2; |
| |
| struct Pending { |
| const ast::Expression* expr; |
| size_t depth; |
| }; |
| |
| utils::Vector<Pending, 64> to_visit{{root, 0}}; |
| |
| auto push_single = [&](const ast::Expression* expr, size_t depth) { |
| to_visit.Push({expr, depth}); |
| }; |
| auto push_pair = [&](const ast::Expression* left, const ast::Expression* right, size_t depth) { |
| if (ORDER == TraverseOrder::LeftToRight) { |
| to_visit.Push({right, depth}); |
| to_visit.Push({left, depth}); |
| } else { |
| to_visit.Push({left, depth}); |
| to_visit.Push({right, depth}); |
| } |
| }; |
| auto push_list = [&](const std::vector<const ast::Expression*>& exprs, size_t depth) { |
| if (ORDER == TraverseOrder::LeftToRight) { |
| for (auto* expr : utils::Reverse(exprs)) { |
| to_visit.Push({expr, depth}); |
| } |
| } else { |
| for (auto* expr : exprs) { |
| to_visit.Push({expr, depth}); |
| } |
| } |
| }; |
| |
| while (!to_visit.IsEmpty()) { |
| auto p = to_visit.Pop(); |
| const ast::Expression* expr = p.expr; |
| |
| if (auto* filtered = expr->template As<EXPR_TYPE>()) { |
| TraverseAction result; |
| if constexpr (kHasDepthArg) { |
| result = callback(filtered, p.depth); |
| } else { |
| result = callback(filtered); |
| } |
| |
| switch (result) { |
| case TraverseAction::Stop: |
| return true; |
| case TraverseAction::Skip: |
| continue; |
| case TraverseAction::Descend: |
| break; |
| } |
| } |
| |
| bool ok = Switch( |
| expr, |
| [&](const IndexAccessorExpression* idx) { |
| push_pair(idx->object, idx->index, p.depth + 1); |
| return true; |
| }, |
| [&](const BinaryExpression* bin_op) { |
| push_pair(bin_op->lhs, bin_op->rhs, p.depth + 1); |
| return true; |
| }, |
| [&](const BitcastExpression* bitcast) { |
| push_single(bitcast->expr, p.depth + 1); |
| return true; |
| }, |
| [&](const CallExpression* call) { |
| // TODO(crbug.com/tint/1257): Resolver breaks if we actually include |
| // the function name in the traversal. push_single(call->func); |
| push_list(call->args, p.depth + 1); |
| return true; |
| }, |
| [&](const MemberAccessorExpression* member) { |
| // TODO(crbug.com/tint/1257): Resolver breaks if we actually include |
| // the member name in the traversal. push_pair(member->member, p.depth + 1); |
| push_single(member->structure, p.depth + 1); |
| return true; |
| }, |
| [&](const UnaryOpExpression* unary) { |
| push_single(unary->expr, p.depth + 1); |
| return true; |
| }, |
| [&](Default) { |
| if (expr->IsAnyOf<LiteralExpression, IdentifierExpression, PhonyExpression>()) { |
| return true; // Leaf expression |
| } |
| TINT_ICE(AST, diags) << "unhandled expression type: " << expr->TypeInfo().name; |
| return false; |
| }); |
| if (!ok) { |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| } // namespace tint::ast |
| |
| #endif // SRC_TINT_AST_TRAVERSE_EXPRESSIONS_H_ |