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Minor Visitors Improvement #7411

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merged 1 commit into from
Oct 21, 2019
Merged

Minor Visitors Improvement #7411

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8 changes: 4 additions & 4 deletions dbms/src/Interpreters/CrossToInnerJoinVisitor.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -94,7 +94,7 @@ class CheckExpressionVisitorData
, ands_only(true)
{}

void visit(const ASTFunction & node, ASTPtr & ast)
void visit(const ASTFunction & node, const ASTPtr & ast)
{
if (!ands_only)
return;
Expand Down Expand Up @@ -231,8 +231,8 @@ class CheckExpressionVisitorData
}
};

using CheckExpressionMatcher = OneTypeMatcher<CheckExpressionVisitorData, false>;
using CheckExpressionVisitor = InDepthNodeVisitor<CheckExpressionMatcher, true>;
using CheckExpressionMatcher = ConstOneTypeMatcher<CheckExpressionVisitorData, false>;
using CheckExpressionVisitor = ConstInDepthNodeVisitor<CheckExpressionMatcher, true>;


bool getTables(ASTSelectQuery & select, std::vector<JoinedTable> & joined_tables, size_t & num_comma)
Expand Down Expand Up @@ -314,7 +314,7 @@ void CrossToInnerJoinMatcher::visit(ASTSelectQuery & select, ASTPtr &, Data & da
return;

CheckExpressionVisitor::Data visitor_data{joined_tables};
CheckExpressionVisitor(visitor_data).visit(select.refWhere());
CheckExpressionVisitor(visitor_data).visit(select.where());

if (visitor_data.complex())
return;
Expand Down
36 changes: 10 additions & 26 deletions dbms/src/Interpreters/InDepthNodeVisitor.h
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Expand Up @@ -10,13 +10,13 @@ namespace DB

/// Visits AST tree in depth, call functions for nodes according to Matcher type data.
/// You need to define Data, visit() and needChildVisit() in Matcher class.
template <typename Matcher, bool _top_to_bottom, typename T>
class InDepthNodeVisitorTemplate
template <typename Matcher, bool _top_to_bottom, typename T = ASTPtr>
class InDepthNodeVisitor
{
public:
using Data = typename Matcher::Data;

InDepthNodeVisitorTemplate(Data & data_, std::ostream * ostr_ = nullptr)
InDepthNodeVisitor(Data & data_, std::ostream * ostr_ = nullptr)
: data(data_),
visit_depth(0),
ostr(ostr_)
Expand Down Expand Up @@ -49,42 +49,26 @@ class InDepthNodeVisitorTemplate
};

template <typename Matcher, bool top_to_bottom>
using InDepthNodeVisitor = InDepthNodeVisitorTemplate<Matcher, top_to_bottom, ASTPtr>;

template <typename Matcher, bool top_to_bottom>
using ConstInDepthNodeVisitor = InDepthNodeVisitorTemplate<Matcher, top_to_bottom, const ASTPtr>;
using ConstInDepthNodeVisitor = InDepthNodeVisitor<Matcher, top_to_bottom, const ASTPtr>;

/// Simple matcher for one node type without complex traversal logic.
template <typename _Data, bool _visit_children = true>
template <typename Data_, bool visit_children = true, typename T = ASTPtr>
class OneTypeMatcher
{
public:
using Data = _Data;
using Data = Data_;
using TypeToVisit = typename Data::TypeToVisit;

static bool needChildVisit(ASTPtr &, const ASTPtr &) { return _visit_children; }
static bool needChildVisit(const ASTPtr &, const ASTPtr &) { return visit_children; }

static void visit(ASTPtr & ast, Data & data)
static void visit(T & ast, Data & data)
{
if (auto * t = typeid_cast<TypeToVisit *>(ast.get()))
data.visit(*t, ast);
}
};

/// Links two simple matches into resulting one. There's no complex traversal logic: all the children would be visited.
template <typename First, typename Second>
class LinkedMatcher
{
public:
using Data = std::pair<typename First::Data, typename Second::Data>;

static bool needChildVisit(ASTPtr &, const ASTPtr &) { return true; }

static void visit(ASTPtr & ast, Data & data)
{
First::visit(ast, data.first);
Second::visit(ast, data.second);
}
};
template <typename Data, bool visit_children = true>
using ConstOneTypeMatcher = OneTypeMatcher<Data, visit_children, const ASTPtr>;

}
33 changes: 11 additions & 22 deletions dbms/src/Interpreters/JoinToSubqueryTransformVisitor.cpp
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Expand Up @@ -37,8 +37,6 @@ namespace
class ExtractAsterisksMatcher
{
public:
using Visitor = InDepthNodeVisitor<ExtractAsterisksMatcher, true>;

struct Data
{
std::unordered_map<String, NamesAndTypesList> table_columns;
Expand Down Expand Up @@ -76,30 +74,16 @@ class ExtractAsterisksMatcher
}
};

static bool needChildVisit(ASTPtr &, const ASTPtr &) { return false; }
static bool needChildVisit(const ASTPtr &, const ASTPtr &) { return false; }

static void visit(ASTPtr & ast, Data & data)
static void visit(const ASTPtr & ast, Data & data)
{
if (auto * t = ast->as<ASTSelectQuery>())
visit(*t, ast, data);
if (auto * t = ast->as<ASTExpressionList>())
visit(*t, ast, data);
}

private:
static void visit(ASTSelectQuery & node, ASTPtr &, Data & data)
{
if (data.table_columns.empty())
return;

Visitor(data).visit(node.refSelect());
if (!data.new_select_expression_list)
return;

node.setExpression(ASTSelectQuery::Expression::SELECT, std::move(data.new_select_expression_list));
}

static void visit(ASTExpressionList & node, ASTPtr &, Data & data)
static void visit(const ASTExpressionList & node, const ASTPtr &, Data & data)
{
bool has_asterisks = false;
data.new_select_expression_list = std::make_shared<ASTExpressionList>();
Expand Down Expand Up @@ -375,7 +359,7 @@ using RewriteMatcher = OneTypeMatcher<RewriteTablesVisitorData>;
using RewriteVisitor = InDepthNodeVisitor<RewriteMatcher, true>;
using SetSubqueryAliasMatcher = OneTypeMatcher<SetSubqueryAliasVisitorData>;
using SetSubqueryAliasVisitor = InDepthNodeVisitor<SetSubqueryAliasMatcher, true>;
using ExtractAsterisksVisitor = ExtractAsterisksMatcher::Visitor;
using ExtractAsterisksVisitor = ConstInDepthNodeVisitor<ExtractAsterisksMatcher, true>;
using ColumnAliasesVisitor = ConstInDepthNodeVisitor<ColumnAliasesMatcher, true>;
using AppendSemanticMatcher = OneTypeMatcher<AppendSemanticVisitorData>;
using AppendSemanticVisitor = InDepthNodeVisitor<AppendSemanticMatcher, true>;
Expand All @@ -389,7 +373,7 @@ void JoinToSubqueryTransformMatcher::visit(ASTPtr & ast, Data & data)
visit(*t, ast, data);
}

void JoinToSubqueryTransformMatcher::visit(ASTSelectQuery & select, ASTPtr & ast, Data & data)
void JoinToSubqueryTransformMatcher::visit(ASTSelectQuery & select, ASTPtr &, Data & data)
{
using RevertedAliases = AsteriskSemantic::RevertedAliases;

Expand All @@ -398,7 +382,12 @@ void JoinToSubqueryTransformMatcher::visit(ASTSelectQuery & select, ASTPtr & ast
return;

ExtractAsterisksVisitor::Data asterisks_data(data.context, table_expressions);
ExtractAsterisksVisitor(asterisks_data).visit(ast);
if (!asterisks_data.table_columns.empty())
{
ExtractAsterisksVisitor(asterisks_data).visit(select.select());
if (asterisks_data.new_select_expression_list)
select.setExpression(ASTSelectQuery::Expression::SELECT, std::move(asterisks_data.new_select_expression_list));
}

ColumnAliasesVisitor::Data aliases_data(getDatabaseAndTables(select, ""));
if (select.select())
Expand Down