CoinbaSeQL

grammar SqlQuery;

// If you update this grammar, simply run `make gen` from the top-level to update the parsing logic.
// Inspired by ClickHouse parser and lexer:
// https://github.com/abyss7/ClickHouse/blob/master/src/Parsers/New/ClickHouseParser.g4
// https://github.com/abyss7/ClickHouse/blob/master/src/Parsers/New/ClickHouseLexer.g4

// Parser rules
query: cteClause? unionStatement SEMICOLON? EOF;

unionStatement:
	unionSelect (unionOperator unionSelect)* (
		ORDER BY orderByElements
	)? (LIMIT limitClause)?;

unionSelect: selectStatement | LPAREN selectStatement RPAREN;

unionOperator: UNION ALL | UNION DISTINCT | UNION;

cteClause: WITH cteDefinition (COMMA cteDefinition)*;

cteDefinition:
	cteName (LPAREN columnList RPAREN)? AS LPAREN selectStatement RPAREN;

cteName: identifier;

columnList: identifier (COMMA identifier)*;

selectStatement:
	SELECT (DISTINCT)? selectElements FROM tableExpression (
		WHERE condition
	)? (GROUP BY groupByElements)? (ORDER BY orderByElements)? (
		LIMIT limitClause
	)?
	| SELECT (DISTINCT)? selectElements // For literals/expressions without FROM
	(ORDER BY orderByElements)? (LIMIT limitClause)?;

selectElements: STAR | selectElement (COMMA selectElement)*;

selectElement: expression (AS? alias)? | tableWildcard;

tableWildcard: (identifier DOT)? STAR;

tableExpression: tableReference (joinExpression)*;

tableReference:
	tableOrCteReference (AS? alias)?
	| LPAREN selectStatement RPAREN (AS? alias)?
	| LPAREN unionStatement RPAREN (AS? alias)?;

tableOrCteReference: tableName | identifier;

joinExpression: joinType? JOIN tableReference ON condition;

joinType: INNER | LEFT | RIGHT | FULL;

condition: expression;

groupByElements: expression (COMMA expression)*;

orderByElements: orderByElement (COMMA orderByElement)*;

orderByElement: expression (ASC | DESC)?;

limitClause: INTEGER_LITERAL;

expression:
	expression BETWEEN expression AND expression
	| expression IN LPAREN (expressionList | selectStatement) RPAREN
	| expression IS (NOT)? NULL
	| expression binaryOperator expression
	| expression CAST_OP dataType // PostgreSQL-style casting (e.g., 1::Int32)
	| expression DOT identifier // Dot notation
	| expression LBRACKET expression RBRACKET // Array/map indexing
	| functionCall
	| castExpression // Standard SQL CAST function
	| LPAREN expression RPAREN
	| CASE (expression)? whenClause+ (ELSE expression)? END
	| primaryExpression;

castExpression: CAST LPAREN expression AS dataType RPAREN;

dataType:
	identifier (LPAREN typeArguments RPAREN)?
	| ARRAY LPAREN dataType RPAREN // Array(Int32)
	| MAP LPAREN dataType COMMA dataType RPAREN // Map(String, String)
	| TUPLE LPAREN dataType (COMMA dataType)* RPAREN; // Tuple(Int32, String)

typeArguments: typeArgument (COMMA typeArgument)*;

typeArgument: dataType | INTEGER_LITERAL;

whenClause: WHEN expression THEN expression;

expressionList: expression (COMMA expression)*;

primaryExpression:
	columnReference
	| literal
	| arrayLiteral // Array literal [1, 2, 3]
	| mapLiteral // Map literal {'key': 'value'}
	| tupleLiteral // Tuple literal (1, 'a', true)
	| LPAREN selectStatement RPAREN; // Subquery as primary expression

columnReference: (tableOrCtePrefix DOT)? columnName;

tableOrCtePrefix: tableName | identifier;

functionCall: identifier LPAREN functionArgs? RPAREN;

lambda: lambdaParams ARROW expression;

lambdaParams:
	identifier
	| LPAREN (identifier (COMMA identifier)*)? RPAREN;

functionArgs:
	STAR
	| DISTINCT expressionList
	| lambda (COMMA expressionList)?
	| expressionList;

binaryOperator:
	EQ
	| NEQ
	| LT
	| LE
	| GT
	| GE
	| PLUS
	| MINUS
	| STAR
	| DIV
	| MOD
	| AND
	| OR
	| LIKE;

literal:
	STRING_LITERAL
	| INTEGER_LITERAL
	| DECIMAL_LITERAL
	| NULL
	| TRUE
	| FALSE;

arrayLiteral:
	LBRACKET (expression (COMMA expression)*)? RBRACKET;

mapLiteral:
	LBRACE (mapEntry (COMMA mapEntry)*)? RBRACE
	| MAP LPAREN (mapPair (COMMA mapPair)*)? RPAREN;

mapEntry: expression COLON expression;

mapPair: expression COMMA expression;

tupleLiteral:
	LPAREN expression (COMMA expression)+ RPAREN // Requires at least 2 elements
	| TUPLE LPAREN (expression (COMMA expression)*)? RPAREN;

tableName: identifier (DOT identifier)?;

columnName: identifier;

functionName: identifier;

alias: identifier;

identifier: IDENTIFIER | QUOTED_IDENTIFIER | keyword;

// All keywords that can potentially be used as identifiers
keyword:
	SELECT
	| FROM
	| WHERE
	| GROUP
	| BY
	| ORDER
	| LIMIT
	| AS
	| JOIN
	| ON
	| INNER
	| LEFT
	| RIGHT
	| FULL
	| AND
	| OR
	| NOT
	| IN
	| BETWEEN
	| LIKE
	| IS
	| NULL
	| TRUE
	| FALSE
	| CASE
	| WHEN
	| THEN
	| ELSE
	| END
	| DISTINCT
	| ASC
	| DESC
	| CAST
	| WITH
	| UNION
	| ALL
	| ARRAY
	| MAP
	| TUPLE
	| OFFSET
	| OUTER;

// Lexer rules - Keywords
SELECT: S E L E C T;
FROM: F R O M;
WHERE: W H E R E;
GROUP: G R O U P;
BY: B Y;
ORDER: O R D E R;
LIMIT: L I M I T;
AS: A S;
JOIN: J O I N;
ON: O N;
INNER: I N N E R;
LEFT: L E F T;
RIGHT: R I G H T;
FULL: F U L L;
AND: A N D;
OR: O R;
NOT: N O T;
IN: I N;
BETWEEN: B E T W E E N;
LIKE: L I K E;
IS: I S;
NULL: N U L L;
TRUE: T R U E;
FALSE: F A L S E;
CASE: C A S E;
WHEN: W H E N;
THEN: T H E N;
ELSE: E L S E;
END: E N D;
DISTINCT: D I S T I N C T;
ASC: A S C;
DESC: D E S C;
CAST: C A S T;
WITH: W I T H;
UNION: U N I O N;
ALL: A L L;
ARRAY: A R R A Y;
MAP: M A P;
TUPLE: T U P L E;
OFFSET: O F F S E T;
OUTER: O U T E R;

// Lexer rules - Comparison Operators
EQ: '=';
NEQ: '!=' | '<>';
LT: '<';
GT: '>';
LE: '<=';
GE: '>=';

// Lexer rules - Arithmetic Operators
PLUS: '+';
MINUS: '-';
STAR: '*';
DIV: '/';
MOD: '%';
ARROW: '->';

// Lexer rules - Delimiters
LPAREN: '(';
RPAREN: ')';
COMMA: ',';
SEMICOLON: ';';
DOT: '.';
LBRACKET: '[';
RBRACKET: ']';
LBRACE: '{';
RBRACE: '}';
COLON: ':';
CAST_OP: '::';

// Lexer rules - Literals
STRING_LITERAL: '\'' (~['])* '\'';

INTEGER_LITERAL: [0-9]+;

DECIMAL_LITERAL: [0-9]+ '.' [0-9]* | '.' [0-9]+;

IDENTIFIER: [a-zA-Z_] [a-zA-Z_0-9]*;

QUOTED_IDENTIFIER:
	'"' (~'"' | '""')* '"'
	| '`' (~'`' | '``')* '`';

// Whitespace and comments
WS: [ \t\r\n]+ -> skip;
COMMENT: '--' ~[\r\n]* -> skip;
MULTI_LINE_COMMENT: '/*' .*? '*/' -> skip;

// Case-insensitive matching fragments
fragment A: [aA];
fragment B: [bB];
fragment C: [cC];
fragment D: [dD];
fragment E: [eE];
fragment F: [fF];
fragment G: [gG];
fragment H: [hH];
fragment I: [iI];
fragment J: [jJ];
fragment K: [kK];
fragment L: [lL];
fragment M: [mM];
fragment N: [nN];
fragment O: [oO];
fragment P: [pP];
fragment Q: [qQ];
fragment R: [rR];
fragment S: [sS];
fragment T: [tT];
fragment U: [uU];
fragment V: [vV];
fragment W: [wW];
fragment X: [xX];
fragment Y: [yY];
fragment Z: [zZ];