ClickHouse/src/Interpreters/ConvertFunctionOrLikeVisitor.cpp

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#include <Interpreters/ConvertFunctionOrLikeVisitor.h>
#include <Parsers/ASTFunction.h>
#include <Parsers/ASTIdentifier.h>
#include <Parsers/ASTLiteral.h>
#include <Parsers/IAST.h>
#include <Common/likePatternToRegexp.h>
#include <Common/typeid_cast.h>
namespace DB
{
void ConvertFunctionOrLikeData::visit(ASTFunction & function, ASTPtr &)
{
if (function.name != "or")
return;
std::unordered_map<String, std::shared_ptr<ASTLiteral>> identifier_to_literals;
for (auto & child : function.children)
{
if (auto * expr_list_fn = child->as<ASTExpressionList>())
{
ASTs unique_elems;
for (const auto & child_expr_fn : expr_list_fn->children)
{
unique_elems.push_back(child_expr_fn);
if (const auto * child_fn = child_expr_fn->as<ASTFunction>())
{
const bool is_like = child_fn->name == "like";
const bool is_ilike = child_fn->name == "ilike";
/// Not {i}like -> bail out.
if (!is_like && !is_ilike)
continue;
const auto & arguments = child_fn->arguments->children;
/// They should have 2 arguments.
if (arguments.size() != 2)
continue;
/// Second one is string literal.
auto identifier = arguments[0];
auto * literal = arguments[1]->as<ASTLiteral>();
if (!identifier || !literal || literal->value.getType() != Field::Types::String)
continue;
String regexp = likePatternToRegexp(literal->value.get<String>());
/// Case insensitive. Works with UTF-8 as well.
if (is_ilike)
regexp = "(?i)" + regexp;
unique_elems.pop_back();
auto it = identifier_to_literals.find(identifier->getAliasOrColumnName());
if (it == identifier_to_literals.end())
{
it = identifier_to_literals.insert({identifier->getAliasOrColumnName(), std::make_shared<ASTLiteral>(Field{Array{}})}).first;
auto match = makeASTFunction("multiMatchAny");
match->arguments->children.push_back(arguments[0]);
match->arguments->children.push_back(it->second);
unique_elems.push_back(std::move(match));
}
it->second->value.get<Array>().push_back(regexp);
}
}
/// OR must have at least two arguments.
if (unique_elems.size() == 1)
unique_elems.push_back(std::make_shared<ASTLiteral>(Field(false)));
expr_list_fn->children = std::move(unique_elems);
}
}
}
}