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#include <Common/SipHash.h>
#include <Common/FieldVisitorToString.h>
#include <Common/FieldVisitorHash.h>
#include <Parsers/ASTLiteral.h>
#include <IO/WriteHelpers.h>
#include <IO/WriteBufferFromString.h>
#include <IO/Operators.h>
namespace DB
{
void ASTLiteral::updateTreeHashImpl(SipHash & hash_state) const
{
const char * prefix = "Literal_";
hash_state.update(prefix, strlen(prefix));
applyVisitor(FieldVisitorHash(hash_state), value);
}
ASTPtr ASTLiteral::clone() const
{
auto res = std::make_shared<ASTLiteral>(*this);
res->unique_column_name = {};
return res;
}
namespace
{
/// Writes 'tuple' word before tuple literals for backward compatibility reasons.
class FieldVisitorToColumnName : public StaticVisitor<String>
{
public:
template<typename T>
String operator() (const T & x) const { return visitor(x); }
private:
FieldVisitorToString visitor;
};
template<>
String FieldVisitorToColumnName::operator() (const Tuple & x) const
{
WriteBufferFromOwnString wb;
wb << "tuple(";
for (auto it = x.begin(); it != x.end(); ++it)
{
if (it != x.begin())
wb << ", ";
wb << applyVisitor(*this, *it);
}
wb << ')';
return wb.str();
}
}
void ASTLiteral::appendColumnNameImpl(WriteBuffer & ostr) const
{
if (use_legacy_column_name_of_tuple)
{
appendColumnNameImplLegacy(ostr);
return;
}
/// 100 - just arbitrary value.
constexpr auto min_elements_for_hashing = 100;
/// Special case for very large arrays and tuples. Instead of listing all elements, will use hash of them.
/// (Otherwise column name will be too long, that will lead to significant slowdown of expression analysis.)
auto type = value.getType();
if ((type == Field::Types::Array && value.get<const Array &>().size() > min_elements_for_hashing)
|| (type == Field::Types::Tuple && value.get<const Tuple &>().size() > min_elements_for_hashing))
{
SipHash hash;
applyVisitor(FieldVisitorHash(hash), value);
UInt64 low, high;
hash.get128(low, high);
writeCString(type == Field::Types::Array ? "__array_" : "__tuple_", ostr);
writeText(low, ostr);
ostr.write('_');
writeText(high, ostr);
}
else
{
String column_name = applyVisitor(FieldVisitorToString(), value);
writeString(column_name, ostr);
}
}
void ASTLiteral::appendColumnNameImplLegacy(WriteBuffer & ostr) const
{
/// 100 - just arbitrary value.
constexpr auto min_elements_for_hashing = 100;
/// Special case for very large arrays. Instead of listing all elements, will use hash of them.
/// (Otherwise column name will be too long, that will lead to significant slowdown of expression analysis.)
auto type = value.getType();
if ((type == Field::Types::Array && value.get<const Array &>().size() > min_elements_for_hashing))
{
SipHash hash;
applyVisitor(FieldVisitorHash(hash), value);
UInt64 low, high;
hash.get128(low, high);
writeCString("__array_", ostr);
writeText(low, ostr);
ostr.write('_');
writeText(high, ostr);
}
else
{
String column_name = applyVisitor(FieldVisitorToColumnName(), value);
writeString(column_name, ostr);
}
}
/// Use different rules for escaping backslashes and quotes
class FieldVisitorToStringPostgreSQL : public StaticVisitor<String>
{
public:
template<typename T>
String operator() (const T & x) const { return visitor(x); }
private:
FieldVisitorToString visitor;
};
template<>
String FieldVisitorToStringPostgreSQL::operator() (const String & x) const
{
WriteBufferFromOwnString wb;
writeQuotedStringPostgreSQL(x, wb);
return wb.str();
}
void ASTLiteral::formatImplWithoutAlias(const FormatSettings & settings, IAST::FormatState &, IAST::FormatStateStacked) const
{
if (settings.literal_escaping_style == LiteralEscapingStyle::Regular)
settings.ostr << applyVisitor(FieldVisitorToString(), value);
else
settings.ostr << applyVisitor(FieldVisitorToStringPostgreSQL(), value);
}
}
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