parser

README

Parser - A MySQL Compatible SQL Parser

The goal of this project is to build a Golang parser that is fully compatible with MySQL syntax, easy to extend, and high performance. Currently, features supported by parser are as follows:

• Highly compatible with MySQL: it supports almost all features of MySQL. For the complete details, see parser.y and hintparser.y.
• Extensible: adding a new syntax requires only a few lines of Yacc and Golang code changes. As an example, see PR-680.
• Good performance: the parser is generated by goyacc in a bottom-up approach. It is efficient to build an AST tree with a state machine.

How to use it

Please read the quickstart.

Future

• Support more MySQL syntax
• Optimize the code structure, make it easier to extend
• Improve performance and benchmark
• Improve the quality of code and comments

Getting Help

• GitHub Issue
• Stack Overflow
• User Group (Chinese)

If you have any questions, feel free to join and discuss in #sig-ddl channel of Slack-community.

If you want to join as a special interest group member, see DDL Special Interest Group.

Users

These projects use this parser. Please feel free to extend this list if you found you are one of the users but not listed here:

• pingcap/tidb
• XiaoMi/soar
• XiaoMi/Gaea
• sql-machine-learning/sqlflow

Contributing

Contributions are welcomed and greatly appreciated. See CONTRIBUTING.md for details on submitting patches and the contribution workflow.

Here is how to update parser for TiDB.

Acknowledgments

Thanks cznic for providing some great open-source tools.

License

Parser is under the Apache 2.0 license. See the LICENSE file for details.

Documentation

Index

• Variables
• func DigestHash(sql string) (result string)
• func DigestNormalized(normalized string) (result string)
• func Normalize(sql string) (result string)
• func NormalizeDigest(sql string) (normalized, digest string)
• func ParseErrorWith(errstr string, lineno int) error
• func ParseHint(input string, sqlMode mysql.SQLMode, initPos Pos) ([]*ast.TableOptimizerHint, []error)
• func TrimComment(txt string) string
• type Parser
  • func New() *Parser
  • func (parser *Parser) EnableWindowFunc(val bool)
  • func (parser *Parser) Parse(sql, charset, collation string) (stmt []ast.StmtNode, warns []error, err error)
  • func (parser *Parser) ParseOneStmt(sql, charset, collation string) (ast.StmtNode, error)
  • func (parser *Parser) SetSQLMode(mode mysql.SQLMode)
• type Pos
• type Scanner
  • func NewScanner(s string) *Scanner
  • func (s *Scanner) AppendError(err error)
  • func (s *Scanner) EnableWindowFunc(val bool)
  • func (s *Scanner) Errorf(format string, a ...interface{}) (err error)
  • func (s *Scanner) Errors() (warns []error, errs []error)
  • func (s *Scanner) GetSQLMode() mysql.SQLMode
  • func (s *Scanner) InheritScanner(sql string) *Scanner
  • func (s *Scanner) Lex(v *yySymType) int
  • func (s *Scanner) SetSQLMode(mode mysql.SQLMode)

Variables

var (
	ErrWarnOptimizerHintUnsupportedHint = terror.ClassParser.New(mysql.ErrWarnOptimizerHintUnsupportedHint, mysql.MySQLErrName[mysql.ErrWarnOptimizerHintUnsupportedHint])
	ErrWarnOptimizerHintInvalidToken    = terror.ClassParser.New(mysql.ErrWarnOptimizerHintInvalidToken, mysql.MySQLErrName[mysql.ErrWarnOptimizerHintInvalidToken])
	ErrWarnMemoryQuotaOverflow          = terror.ClassParser.New(mysql.ErrWarnMemoryQuotaOverflow, mysql.MySQLErrName[mysql.ErrWarnMemoryQuotaOverflow])
	ErrWarnOptimizerHintParseError      = terror.ClassParser.New(mysql.ErrWarnOptimizerHintParseError, mysql.MySQLErrName[mysql.ErrWarnOptimizerHintParseError])
	ErrWarnOptimizerHintInvalidInteger  = terror.ClassParser.New(mysql.ErrWarnOptimizerHintInvalidInteger, mysql.MySQLErrName[mysql.ErrWarnOptimizerHintInvalidInteger])
)

var (
	// ErrSyntax returns for sql syntax error.
	ErrSyntax = terror.ClassParser.New(mysql.ErrSyntax, mysql.MySQLErrName[mysql.ErrSyntax])
	// ErrParse returns for sql parse error.
	ErrParse = terror.ClassParser.New(mysql.ErrParse, mysql.MySQLErrName[mysql.ErrParse])
	// ErrUnknownCharacterSet returns for no character set found error.
	ErrUnknownCharacterSet = terror.ClassParser.New(mysql.ErrUnknownCharacterSet, mysql.MySQLErrName[mysql.ErrUnknownCharacterSet])
	// ErrInvalidYearColumnLength returns for illegal column length for year type.
	ErrInvalidYearColumnLength = terror.ClassParser.New(mysql.ErrInvalidYearColumnLength, mysql.MySQLErrName[mysql.ErrInvalidYearColumnLength])
	// ErrWrongArguments returns for illegal argument.
	ErrWrongArguments = terror.ClassParser.New(mysql.ErrWrongArguments, mysql.MySQLErrName[mysql.ErrWrongArguments])
	// ErrWrongFieldTerminators returns for illegal field terminators.
	ErrWrongFieldTerminators = terror.ClassParser.New(mysql.ErrWrongFieldTerminators, mysql.MySQLErrName[mysql.ErrWrongFieldTerminators])
	// ErrTooBigDisplayWidth returns for data display width exceed limit .
	ErrTooBigDisplayWidth = terror.ClassParser.New(mysql.ErrTooBigDisplaywidth, mysql.MySQLErrName[mysql.ErrTooBigDisplaywidth])
	// ErrTooBigPrecision returns for data precision exceed limit.
	ErrTooBigPrecision = terror.ClassParser.New(mysql.ErrTooBigPrecision, mysql.MySQLErrName[mysql.ErrTooBigPrecision])
	// ErrUnknownAlterLock returns for no alter lock type found error.
	ErrUnknownAlterLock = terror.ClassParser.New(mysql.ErrUnknownAlterLock, mysql.MySQLErrName[mysql.ErrUnknownAlterLock])
	// ErrUnknownAlterAlgorithm returns for no alter algorithm found error.
	ErrUnknownAlterAlgorithm = terror.ClassParser.New(mysql.ErrUnknownAlterAlgorithm, mysql.MySQLErrName[mysql.ErrUnknownAlterAlgorithm])
	// ErrWrongValue returns for wrong value
	ErrWrongValue = terror.ClassParser.New(mysql.ErrWrongValue, mysql.MySQLErrName[mysql.ErrWrongValue])
	// SpecFieldPattern special result field pattern
	SpecFieldPattern = regexp.MustCompile(`(\/\*!(M?[0-9]{5,6})?|\*\/)`)
)

var SpecialCommentsController = specialCommentsCtrl{
	// contains filtered or unexported fields
}

SpecialCommentsController controls whether special comments like `/*T![xxx] yyy */` can be parsed as `yyy`. To add such rules, please use SpecialCommentsController.Register(). For example:

SpecialCommentsController.Register("30100");

Now the parser will treat

select a, /*T![30100] mysterious_keyword */ from t;

and

select a, mysterious_keyword from t;

equally. Similar special comments without registration are ignored by parser.

Functions

func DigestHash

func DigestHash(sql string) (result string)

DigestHash generates the digest of statements. it will generate a hash on normalized form of statement text which removes general property of a statement but keeps specific property.

for example: both DigestHash('select 1') and DigestHash('select 2') => e1c71d1661ae46e09b7aaec1c390957f0d6260410df4e4bc71b9c8d681021471

Deprecated: It is logically consistent with NormalizeDigest.

func DigestNormalized

func DigestNormalized(normalized string) (result string)

DigestNormalized generates the digest of a normalized sql. it will generate a hash on a normalized sql. Normalize + DigestNormalized equals to NormalizeDigest.

for example: DigestNormalized('select ?') DigestNormalized should be called with a normalized SQL string (like 'select ?') generated by function Normalize. do not call with SQL which is not normalized, DigestNormalized('select 1') and DigestNormalized('select 2') is not the same

func Normalize

func Normalize(sql string) (result string)

Normalize generates the normalized statements. it will get normalized form of statement text which removes general property of a statement but keeps specific property.

for example: Normalize('select 1 from b where a = 1') => 'select ? from b where a = ?'

func NormalizeDigest

func NormalizeDigest(sql string) (normalized, digest string)

NormalizeDigest combines Normalize and DigestNormalized into one method.

func ParseErrorWith

func ParseErrorWith(errstr string, lineno int) error

ParseErrorWith returns "You have a syntax error near..." error message compatible with mysql.

func ParseHint

func ParseHint(input string, sqlMode mysql.SQLMode, initPos Pos) ([]*ast.TableOptimizerHint, []error)

ParseHint parses an optimizer hint (the interior of `/*+ ... */`).

func TrimComment

func TrimComment(txt string) string

TrimComment trim comment for special comment code of MySQL.

Types

type Parser

type Parser struct {
	// contains filtered or unexported fields
}

Parser represents a parser instance. Some temporary objects are stored in it to reduce object allocation during Parse function.

func New

func New() *Parser

New returns a Parser object.

func (*Parser) EnableWindowFunc

func (parser *Parser) EnableWindowFunc(val bool)

EnableWindowFunc controls whether the parser to parse syntax related with window function.

func (*Parser) Parse

func (parser *Parser) Parse(sql, charset, collation string) (stmt []ast.StmtNode, warns []error, err error)

Parse parses a query string to raw ast.StmtNode. If charset or collation is "", default charset and collation will be used.

func (*Parser) ParseOneStmt

func (parser *Parser) ParseOneStmt(sql, charset, collation string) (ast.StmtNode, error)

ParseOneStmt parses a query and returns an ast.StmtNode. The query must have one statement, otherwise ErrSyntax is returned.

func (*Parser) SetSQLMode

func (parser *Parser) SetSQLMode(mode mysql.SQLMode)

SetSQLMode sets the SQL mode for parser.

type Pos

type Pos struct {
	Line   int
	Col    int
	Offset int
}

Pos represents the position of a token.

type Scanner

type Scanner struct {
	// contains filtered or unexported fields
}

Scanner implements the yyLexer interface.

func NewScanner

func NewScanner(s string) *Scanner

NewScanner returns a new scanner object.

func (*Scanner) AppendError

func (s *Scanner) AppendError(err error)

AppendError sets error into scanner. Scanner satisfies yyLexer interface which need this function.

func (*Scanner) EnableWindowFunc

func (s *Scanner) EnableWindowFunc(val bool)

EnableWindowFunc controls whether the scanner recognize the keywords of window function.

func (*Scanner) Errorf

func (s *Scanner) Errorf(format string, a ...interface{}) (err error)

Errorf tells scanner something is wrong. Scanner satisfies yyLexer interface which need this function.

func (*Scanner) Errors

func (s *Scanner) Errors() (warns []error, errs []error)

Errors returns the errors and warns during a scan.

func (*Scanner) GetSQLMode

func (s *Scanner) GetSQLMode() mysql.SQLMode

GetSQLMode return the SQL mode of scanner.

func (*Scanner) InheritScanner

func (s *Scanner) InheritScanner(sql string) *Scanner

InheritScanner returns a new scanner object which inherits configurations from the parent scanner.

func (*Scanner) Lex

func (s *Scanner) Lex(v *yySymType) int

Lex returns a token and store the token value in v. Scanner satisfies yyLexer interface. 0 and invalid are special token id this function would return: return 0 tells parser that scanner meets EOF, return invalid tells parser that scanner meets illegal character.

func (*Scanner) SetSQLMode

func (s *Scanner) SetSQLMode(mode mysql.SQLMode)

SetSQLMode sets the SQL mode for scanner.