ClickHouse/dbms/src/Interpreters/evaluateConstantExpression.cpp

72 lines
2.5 KiB
C++

#include <Core/Block.h>
#include <Columns/ColumnConst.h>
#include <Columns/ColumnsNumber.h>
#include <Parsers/ASTIdentifier.h>
#include <Parsers/ASTLiteral.h>
#include <Parsers/ExpressionElementParsers.h>
#include <DataTypes/DataTypesNumber.h>
#include <Interpreters/Context.h>
#include <Interpreters/ExpressionAnalyzer.h>
#include <Interpreters/ExpressionActions.h>
#include <Interpreters/evaluateConstantExpression.h>
#include <Common/typeid_cast.h>
namespace DB
{
namespace ErrorCodes
{
extern const int LOGICAL_ERROR;
extern const int BAD_ARGUMENTS;
}
std::pair<Field, std::shared_ptr<IDataType>> evaluateConstantExpression(const ASTPtr & node, const Context & context)
{
ExpressionActionsPtr expr_for_constant_folding = ExpressionAnalyzer(
node, context, nullptr, NamesAndTypesList{{ "_dummy", std::make_shared<DataTypeUInt8>() }}).getConstActions();
/// There must be at least one column in the block so that it knows the number of rows.
Block block_with_constants{{ ColumnConst::create(ColumnUInt8::create(1, 0), 1), std::make_shared<DataTypeUInt8>(), "_dummy" }};
expr_for_constant_folding->execute(block_with_constants);
if (!block_with_constants || block_with_constants.rows() == 0)
throw Exception("Logical error: empty block after evaluation of constant expression for IN or VALUES", ErrorCodes::LOGICAL_ERROR);
String name = node->getColumnName();
if (!block_with_constants.has(name))
throw Exception("Element of set in IN or VALUES is not a constant expression: " + name, ErrorCodes::BAD_ARGUMENTS);
const ColumnWithTypeAndName & result = block_with_constants.getByName(name);
const IColumn & result_column = *result.column;
if (!result_column.isColumnConst())
throw Exception("Element of set in IN or VALUES is not a constant expression: " + name, ErrorCodes::BAD_ARGUMENTS);
return std::make_pair(result_column[0], result.type);
}
ASTPtr evaluateConstantExpressionAsLiteral(const ASTPtr & node, const Context & context)
{
if (typeid_cast<const ASTLiteral *>(node.get()))
return node;
return std::make_shared<ASTLiteral>(node->range,
evaluateConstantExpression(node, context).first);
}
ASTPtr evaluateConstantExpressionOrIdentifierAsLiteral(const ASTPtr & node, const Context & context)
{
if (auto id = typeid_cast<const ASTIdentifier *>(node.get()))
return std::make_shared<ASTLiteral>(node->range, Field(id->name));
return evaluateConstantExpressionAsLiteral(node, context);
}
}