ClickHouse/dbms/src/TableFunctions/ITableFunctionFileLike.cpp

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2018-06-11 12:13:00 +00:00
#include <TableFunctions/ITableFunction.h>
#include <TableFunctions/ITableFunctionFileLike.h>
#include <Parsers/ASTFunction.h>
#include <Parsers/ASTLiteral.h>
#include <Common/Exception.h>
#include <Common/typeid_cast.h>
#include <Storages/StorageFile.h>
#include <DataTypes/DataTypeFactory.h>
#include <Interpreters/Context.h>
#include <Interpreters/evaluateConstantExpression.h>
#include <boost/algorithm/string.hpp>
#include <Common/Exception.h>
#include <Common/typeid_cast.h>
namespace DB
{
namespace ErrorCodes
{
extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
}
StoragePtr ITableFunctionFileLike::executeImpl(const ASTPtr & ast_function, const Context & context) const
{
// Parse args
ASTs & args_func = typeid_cast<ASTFunction &>(*ast_function).children;
if (args_func.size() != 1)
throw Exception("Table function '" + getName() + "' must have arguments.", ErrorCodes::LOGICAL_ERROR);
ASTs & args = typeid_cast<ASTExpressionList &>(*args_func.at(0)).children;
if (args.size() != 3)
throw Exception("Table function '" + getName() + "' requires exactly 3 arguments: source, format and structure.",
ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
for (size_t i = 0; i < 3; ++i)
args[i] = evaluateConstantExpressionOrIdentifierAsLiteral(args[i], context);
std::string source = static_cast<const ASTLiteral &>(*args[0]).value.safeGet<String>();
std::string format = static_cast<const ASTLiteral &>(*args[1]).value.safeGet<String>();
std::string structure = static_cast<const ASTLiteral &>(*args[2]).value.safeGet<String>();
// Create sample block
std::vector<std::string> 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));
}
// Create table
StoragePtr storage = getStorage(source, format, sample_block, const_cast<Context &>(context));
storage->startup();
return storage;
}
}