1 | //===----------------------------------------------------------------------===// |
---|---|
2 | // DuckDB |
3 | // |
4 | // duckdb/optimizer/expression_rewriter.hpp |
5 | // |
6 | // |
7 | //===----------------------------------------------------------------------===// |
8 | |
9 | #pragma once |
10 | |
11 | #include "duckdb/optimizer/rule.hpp" |
12 | #include "duckdb/planner/logical_operator_visitor.hpp" |
13 | #include "duckdb/common/types/value.hpp" |
14 | |
15 | namespace duckdb { |
16 | class ClientContext; |
17 | |
18 | //! The ExpressionRewriter performs a set of fixed rewrite rules on the expressions that occur in a SQL statement |
19 | class ExpressionRewriter : public LogicalOperatorVisitor { |
20 | public: |
21 | explicit ExpressionRewriter(ClientContext &context) : context(context) { |
22 | } |
23 | |
24 | public: |
25 | //! The set of rules as known by the Expression Rewriter |
26 | vector<unique_ptr<Rule>> rules; |
27 | |
28 | ClientContext &context; |
29 | |
30 | public: |
31 | void VisitOperator(LogicalOperator &op) override; |
32 | void VisitExpression(unique_ptr<Expression> *expression) override; |
33 | |
34 | // Generates either a constant_or_null(child) expression |
35 | static unique_ptr<Expression> ConstantOrNull(unique_ptr<Expression> child, Value value); |
36 | static unique_ptr<Expression> ConstantOrNull(vector<unique_ptr<Expression>> children, Value value); |
37 | |
38 | private: |
39 | //! Apply a set of rules to a specific expression |
40 | static unique_ptr<Expression> ApplyRules(LogicalOperator &op, const vector<reference<Rule>> &rules, |
41 | unique_ptr<Expression> expr, bool &changes_made, bool is_root = false); |
42 | |
43 | optional_ptr<LogicalOperator> op; |
44 | vector<reference<Rule>> to_apply_rules; |
45 | }; |
46 | |
47 | } // namespace duckdb |
48 |