ClickHouse/dbms/src/Formats/ValuesRowInputStream.cpp

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#include <IO/ReadHelpers.h>
#include <Interpreters/evaluateConstantExpression.h>
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#include <Interpreters/Context.h>
#include <Interpreters/convertFieldToType.h>
#include <Parsers/TokenIterator.h>
#include <Parsers/ExpressionListParsers.h>
#include <Formats/ValuesRowInputStream.h>
#include <Formats/FormatFactory.h>
#include <Formats/BlockInputStreamFromRowInputStream.h>
#include <Common/FieldVisitors.h>
#include <Core/Block.h>
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#include <Common/typeid_cast.h>
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namespace DB
{
namespace ErrorCodes
{
extern const int CANNOT_PARSE_INPUT_ASSERTION_FAILED;
extern const int CANNOT_PARSE_QUOTED_STRING;
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extern const int CANNOT_PARSE_NUMBER;
extern const int CANNOT_PARSE_DATE;
extern const int CANNOT_PARSE_DATETIME;
extern const int CANNOT_READ_ARRAY_FROM_TEXT;
extern const int CANNOT_PARSE_DATE;
extern const int SYNTAX_ERROR;
extern const int VALUE_IS_OUT_OF_RANGE_OF_DATA_TYPE;
}
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ValuesRowInputStream::ValuesRowInputStream(ReadBuffer & istr_, const Block & header_, const Context & context_, const FormatSettings & format_settings)
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: istr(istr_), header(header_), context(std::make_unique<Context>(context_)), format_settings(format_settings)
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{
/// In this format, BOM at beginning of stream cannot be confused with value, so it is safe to skip it.
skipBOMIfExists(istr);
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}
bool ValuesRowInputStream::read(MutableColumns & columns)
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{
size_t num_columns = columns.size();
skipWhitespaceIfAny(istr);
if (istr.eof() || *istr.position() == ';')
return false;
/** Typically, this is the usual format for streaming parsing.
* But as an exception, it also supports processing arbitrary expressions instead of values.
* This is very inefficient. But if there are no expressions, then there is no overhead.
*/
ParserExpression parser;
assertChar('(', istr);
for (size_t i = 0; i < num_columns; ++i)
{
skipWhitespaceIfAny(istr);
char * prev_istr_position = istr.position();
size_t prev_istr_bytes = istr.count() - istr.offset();
bool rollback_on_exception = false;
try
{
header.getByPosition(i).type->deserializeTextQuoted(*columns[i], istr, format_settings);
rollback_on_exception = true;
skipWhitespaceIfAny(istr);
if (i != num_columns - 1)
assertChar(',', istr);
else
assertChar(')', istr);
}
catch (const Exception & e)
{
if (!format_settings.values.interpret_expressions)
throw;
/** The normal streaming parser could not parse the value.
* Let's try to parse it with a SQL parser as a constant expression.
* This is an exceptional case.
*/
if (e.code() == ErrorCodes::CANNOT_PARSE_INPUT_ASSERTION_FAILED
|| e.code() == ErrorCodes::CANNOT_PARSE_QUOTED_STRING
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|| e.code() == ErrorCodes::CANNOT_PARSE_NUMBER
|| e.code() == ErrorCodes::CANNOT_PARSE_DATE
|| e.code() == ErrorCodes::CANNOT_PARSE_DATETIME
|| e.code() == ErrorCodes::CANNOT_READ_ARRAY_FROM_TEXT)
{
/// TODO Case when the expression does not fit entirely in the buffer.
/// If the beginning of the value is no longer in the buffer.
if (istr.count() - istr.offset() != prev_istr_bytes)
throw;
if (rollback_on_exception)
columns[i]->popBack(1);
const IDataType & type = *header.getByPosition(i).type;
Expected expected;
Tokens tokens(prev_istr_position, istr.buffer().end());
TokenIterator token_iterator(tokens);
ASTPtr ast;
if (!parser.parse(token_iterator, ast, expected))
throw Exception("Cannot parse expression of type " + type.getName() + " here: "
+ String(prev_istr_position, std::min(SHOW_CHARS_ON_SYNTAX_ERROR, istr.buffer().end() - prev_istr_position)),
ErrorCodes::SYNTAX_ERROR);
istr.position() = const_cast<char *>(token_iterator->begin);
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std::pair<Field, DataTypePtr> value_raw = evaluateConstantExpression(ast, *context);
Field value = convertFieldToType(value_raw.first, type, value_raw.second.get());
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/// Check that we are indeed allowed to insert a NULL.
if (value.isNull())
{
if (!type.isNullable())
throw Exception{"Expression returns value " + applyVisitor(FieldVisitorToString(), value)
+ ", that is out of range of type " + type.getName()
+ ", at: " + String(prev_istr_position, std::min(SHOW_CHARS_ON_SYNTAX_ERROR, istr.buffer().end() - prev_istr_position)),
ErrorCodes::VALUE_IS_OUT_OF_RANGE_OF_DATA_TYPE};
}
columns[i]->insert(value);
skipWhitespaceIfAny(istr);
if (i != num_columns - 1)
assertChar(',', istr);
else
assertChar(')', istr);
}
else
throw;
}
}
skipWhitespaceIfAny(istr);
if (!istr.eof() && *istr.position() == ',')
++istr.position();
return true;
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}
void registerInputFormatValues(FormatFactory & factory)
{
factory.registerInputFormat("Values", [](
ReadBuffer & buf,
const Block & sample,
const Context & context,
size_t max_block_size,
const FormatSettings & settings)
{
return std::make_shared<BlockInputStreamFromRowInputStream>(
std::make_shared<ValuesRowInputStream>(buf, sample, context, settings),
sample, max_block_size, settings);
});
}
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}