ClickHouse/dbms/src/Storages/ColumnsDescription.cpp

133 lines
3.7 KiB
C++

#include <Parsers/ExpressionListParsers.h>
#include <Parsers/queryToString.h>
#include <IO/WriteBuffer.h>
#include <IO/WriteHelpers.h>
#include <IO/ReadBuffer.h>
#include <IO/ReadHelpers.h>
#include <IO/WriteBufferFromString.h>
#include <IO/ReadBufferFromString.h>
#include <Storages/ColumnsDescription.h>
#include <DataTypes/DataTypeFactory.h>
namespace DB
{
namespace ErrorCodes
{
extern const int CANNOT_PARSE_TEXT;
}
template <bool store>
String ColumnsDescription<store>::toString() const
{
String s;
WriteBufferFromString buf{s};
writeString("columns format version: 1\n", buf);
writeText(columns.size() + materialized.size() + alias.size(), buf);
writeString(" columns:\n", buf);
const auto write_columns = [this, &buf] (const NamesAndTypesList & columns)
{
for (const auto & column : columns)
{
const auto it = defaults.find(column.name);
writeBackQuotedString(column.name, buf);
writeChar(' ', buf);
writeString(column.type->getName(), buf);
if (it == std::end(defaults))
{
writeChar('\n', buf);
continue;
}
else
writeChar('\t', buf);
writeString(DB::toString(it->second.type), buf);
writeChar('\t', buf);
writeString(queryToString(it->second.expression), buf);
writeChar('\n', buf);
}
};
write_columns(columns);
write_columns(materialized);
write_columns(alias);
return s;
}
template <>
ColumnsDescription<true> ColumnsDescription<true>::parse(const String & str)
{
ReadBufferFromString buf{str};
assertString("columns format version: 1\n", buf);
size_t count{};
readText(count, buf);
assertString(" columns:\n", buf);
ParserTernaryOperatorExpression expr_parser;
const DataTypeFactory & data_type_factory = DataTypeFactory::instance();
ColumnsDescription<true> result{};
for (size_t i = 0; i < count; ++i)
{
String column_name;
readBackQuotedString(column_name, buf);
assertChar(' ', buf);
String type_name;
readString(type_name, buf);
auto type = data_type_factory.get(type_name);
if (*buf.position() == '\n')
{
assertChar('\n', buf);
result.columns.emplace_back(column_name, std::move(type));
continue;
}
assertChar('\t', buf);
String default_type_str;
readString(default_type_str, buf);
const auto default_type = columnDefaultTypeFromString(default_type_str);
assertChar('\t', buf);
String default_expr_str;
readText(default_expr_str, buf);
assertChar('\n', buf);
ASTPtr default_expr;
Expected expected{};
auto begin = default_expr_str.data();
const auto end = begin + default_expr_str.size();
const char * max_parsed_pos = begin;
if (!expr_parser.parse(begin, end, default_expr, max_parsed_pos, expected))
throw Exception{"Could not parse default expression", DB::ErrorCodes::CANNOT_PARSE_TEXT};
if (ColumnDefaultType::Default == default_type)
result.columns.emplace_back(column_name, std::move(type));
else if (ColumnDefaultType::Materialized == default_type)
result.materialized.emplace_back(column_name, std::move(type));
else if (ColumnDefaultType::Alias == default_type)
result.alias.emplace_back(column_name, std::move(type));
result.defaults.emplace(column_name, ColumnDefault{default_type, default_expr});
}
assertEOF(buf);
return result;
}
template struct ColumnsDescription<false>;
template struct ColumnsDescription<true>;
}