ClickHouse/src/TableFunctions/ITableFunctionFileLike.h

#pragma once

#include <TableFunctions/ITableFunction.h>
#include "Parsers/IAST_fwd.h"

namespace DB
{
class ColumnsDescription;
class Context;

/*
 * function(source, format, structure[, compression_method]) - creates a temporary storage from formatted source
 */
class ITableFunctionFileLike : public ITableFunction
{
public:
    bool needStructureHint() const override { return structure == "auto"; }

    void setStructureHint(const ColumnsDescription & structure_hint_) override { structure_hint = structure_hint_; }

    bool supportsReadingSubsetOfColumns() override;

protected:
    void parseArguments(const ASTPtr & ast_function, ContextPtr context) override;
    virtual void parseFirstArguments(const ASTPtr & arg, const ContextPtr & context);
    virtual String getFormatFromFirstArgument();

    String filename;
    String format = "auto";
    String structure = "auto";
    String compression_method = "auto";
    ColumnsDescription structure_hint;

private:
    StoragePtr executeImpl(const ASTPtr & ast_function, ContextPtr context, const std::string & table_name, ColumnsDescription cached_columns) const override;

    virtual StoragePtr getStorage(
        const String & source, const String & format, const ColumnsDescription & columns, ContextPtr global_context,
        const std::string & table_name, const String & compression_method) const = 0;

    bool hasStaticStructure() const override { return structure != "auto"; }
};

}