ClickHouse/dbms/src/TableFunctions/TableFunctionInput.cpp

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2019-05-28 18:27:00 +00:00
#include <TableFunctions/ITableFunction.h>
#include <TableFunctions/TableFunctionInput.h>
#include <TableFunctions/TableFunctionFactory.h>
#include <Parsers/ASTFunction.h>
#include <Parsers/ASTLiteral.h>
#include <Common/Exception.h>
#include <Common/typeid_cast.h>
#include <Storages/StorageInput.h>
#include <DataTypes/DataTypeFactory.h>
#include <Interpreters/Context.h>
#include <Interpreters/evaluateConstantExpression.h>
#include <boost/algorithm/string.hpp>
namespace DB
{
namespace ErrorCodes
{
extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
}
StoragePtr TableFunctionInput::executeImpl(const ASTPtr & ast_function, const Context & context) const
{
const auto * function = ast_function->as<ASTFunction>();
if (!function->arguments)
throw Exception("Table function '" + getName() + "' must have arguments", ErrorCodes::LOGICAL_ERROR);
auto args = function->arguments->children;
if (args.size() != 1)
throw Exception("Table function '" + getName() + "' requires exactly 1 argument: structure",
ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
args[0] = evaluateConstantExpressionOrIdentifierAsLiteral(args[0], context);
String structure = evaluateConstantExpressionOrIdentifierAsLiteral(args[0], context)->as<ASTLiteral &>().value.safeGet<String>();
// Create sample block
Strings structure_vals;
boost::split(structure_vals, structure, boost::algorithm::is_any_of(" ,"), boost::algorithm::token_compress_on);
if (structure_vals.size() % 2 != 0)
throw Exception("Odd number of elements in section structure: must be a list of name type pairs", ErrorCodes::LOGICAL_ERROR);
Block sample_block;
const DataTypeFactory & data_type_factory = DataTypeFactory::instance();
for (size_t i = 0, size = structure_vals.size(); i < size; i += 2)
{
ColumnWithTypeAndName column;
column.name = structure_vals[i];
column.type = data_type_factory.get(structure_vals[i + 1]);
column.column = column.type->createColumn();
sample_block.insert(std::move(column));
}
StoragePtr storage = StorageInput::create(getName(), ColumnsDescription{sample_block.getNamesAndTypesList()});
storage->startup();
return storage;
}
void registerTableFunctionInput(TableFunctionFactory & factory)
{
factory.registerFunction<TableFunctionInput>();
}
}