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81 lines
1.9 KiB
C++
81 lines
1.9 KiB
C++
#pragma once
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#include <typeinfo>
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#include <vector>
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#include <Common/typeid_cast.h>
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#include <Parsers/DumpASTNode.h>
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namespace DB
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{
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/// Visits AST tree in depth, call functions for nodes according to Matcher type data.
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/// You need to define Data, visit() and needChildVisit() in Matcher class.
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template <typename Matcher, bool _top_to_bottom, typename T = ASTPtr>
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class InDepthNodeVisitor
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{
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public:
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using Data = typename Matcher::Data;
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InDepthNodeVisitor(Data & data_, std::ostream * ostr_ = nullptr)
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: data(data_),
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visit_depth(0),
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ostr(ostr_)
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{}
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void visit(T & ast)
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{
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DumpASTNode dump(*ast, ostr, visit_depth, typeid(Matcher).name());
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if constexpr (!_top_to_bottom)
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visitChildren(ast);
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Matcher::visit(ast, data);
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if constexpr (_top_to_bottom)
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visitChildren(ast);
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}
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private:
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Data & data;
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size_t visit_depth;
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std::ostream * ostr;
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void visitChildren(T & ast)
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{
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for (auto & child : ast->children)
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if (Matcher::needChildVisit(ast, child))
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visit(child);
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}
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};
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template <typename Matcher, bool top_to_bottom>
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using ConstInDepthNodeVisitor = InDepthNodeVisitor<Matcher, top_to_bottom, const ASTPtr>;
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/// Simple matcher for one node type without complex traversal logic.
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template <typename Data_, bool visit_children = true, typename T = ASTPtr>
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class OneTypeMatcher
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{
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public:
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using Data = Data_;
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using TypeToVisit = typename Data::TypeToVisit;
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static bool needChildVisit(const ASTPtr & node, const ASTPtr &)
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{
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if (node && node->as<TypeToVisit>())
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return visit_children;
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return true;
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}
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static void visit(T & ast, Data & data)
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{
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if (auto * t = typeid_cast<TypeToVisit *>(ast.get()))
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data.visit(*t, ast);
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}
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};
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template <typename Data, bool visit_children = true>
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using ConstOneTypeMatcher = OneTypeMatcher<Data, visit_children, const ASTPtr>;
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}
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