ClickHouse/src/Interpreters/ReplaceQueryParameterVisitor.cpp

#include <Columns/IColumn.h>
#include <DataTypes/DataTypeFactory.h>
#include <DataTypes/IDataType.h>
#include <Formats/FormatSettings.h>
#include <IO/ReadBufferFromString.h>
#include <Interpreters/IdentifierSemantic.h>
#include <Interpreters/ReplaceQueryParameterVisitor.h>
#include <Interpreters/addTypeConversionToAST.h>
#include <Parsers/ASTIdentifier.h>
#include <Parsers/ASTLiteral.h>
#include <Parsers/ASTQueryParameter.h>
#include <Parsers/TablePropertiesQueriesASTs.h>
#include <Common/quoteString.h>
#include <Common/typeid_cast.h>


namespace DB
{

namespace ErrorCodes
{
    extern const int UNKNOWN_QUERY_PARAMETER;
    extern const int BAD_QUERY_PARAMETER;
}


void ReplaceQueryParameterVisitor::visit(ASTPtr & ast)
{
    if (ast->as<ASTQueryParameter>())
        visitQueryParameter(ast);
    else if (ast->as<ASTIdentifier>() || ast->as<ASTTableIdentifier>())
        visitIdentifier(ast);
    else
    {
        if (auto * describe_query = dynamic_cast<ASTDescribeQuery *>(ast.get()); describe_query && describe_query->table_expression)
            visitChildren(describe_query->table_expression);
        else
            visitChildren(ast);
    }
}


void ReplaceQueryParameterVisitor::visitChildren(ASTPtr & ast)
{
    for (auto & child : ast->children)
        visit(child);
}

const String & ReplaceQueryParameterVisitor::getParamValue(const String & name)
{
    auto search = query_parameters.find(name);
    if (search != query_parameters.end())
        return search->second;
    else
        throw Exception("Substitution " + backQuote(name) + " is not set", ErrorCodes::UNKNOWN_QUERY_PARAMETER);
}

void ReplaceQueryParameterVisitor::visitQueryParameter(ASTPtr & ast)
{
    const auto & ast_param = ast->as<ASTQueryParameter &>();
    const String & value = getParamValue(ast_param.name);
    const String & type_name = ast_param.type;
    String alias = ast_param.alias;

    const auto data_type = DataTypeFactory::instance().get(type_name);
    auto temp_column_ptr = data_type->createColumn();
    IColumn & temp_column = *temp_column_ptr;
    ReadBufferFromString read_buffer{value};
    FormatSettings format_settings;
    data_type->getDefaultSerialization()->deserializeTextEscaped(temp_column, read_buffer, format_settings);

    if (!read_buffer.eof())
        throw Exception(ErrorCodes::BAD_QUERY_PARAMETER,
            "Value {} cannot be parsed as {} for query parameter '{}'"
            " because it isn't parsed completely: only {} of {} bytes was parsed: {}",
            value, type_name, ast_param.name, read_buffer.count(), value.size(), value.substr(0, read_buffer.count()));

    Field literal;
    /// If data type has custom serialization, we should use CAST from String,
    /// because CAST from field may not work correctly (for example for type IPv6).
    if (data_type->getCustomSerialization())
        literal = value;
    else
        literal = temp_column[0];
    ast = addTypeConversionToAST(std::make_shared<ASTLiteral>(literal), type_name);

    /// Keep the original alias.
    ast->setAlias(alias);
}

void ReplaceQueryParameterVisitor::visitIdentifier(ASTPtr & ast)
{
    auto ast_identifier = dynamic_pointer_cast<ASTIdentifier>(ast);
    if (ast_identifier->children.empty())
        return;

    auto & name_parts = ast_identifier->name_parts;
    for (size_t i = 0, j = 0, size = name_parts.size(); i < size; ++i)
    {
        if (name_parts[i].empty())
        {
            const auto & ast_param = ast_identifier->children[j++]->as<ASTQueryParameter &>();
            name_parts[i] = getParamValue(ast_param.name);
        }
    }

    /// FIXME: what should this mean?
    if (!ast_identifier->semantic->special && name_parts.size() >= 2)
        ast_identifier->semantic->table = ast_identifier->name_parts.end()[-2];

    ast_identifier->resetFullName();
    ast_identifier->children.clear();
}

}