token

const (
	// Special tokens
	ILLEGAL Type = iota
	EOF
	COMMENT // // line comment  or  /* block comment */

	// Identifiers and literals
	IDENT     // identifier, label, property key
	INT       // 42
	FLOAT     // 3.14
	STRING    // 'hello' or "hello"
	TRUE      // true
	FALSE     // false
	NULL      // null
	PARAMETER // $param or {param}

	// Operators — arithmetic
	PLUS     // +
	MINUS    // -
	ASTERISK // *
	SLASH    // /
	PERCENT  // %
	CARET    // ^ (exponentiation)

	// Operators — comparison
	EQ  // =
	NEQ // <>
	LT  // <
	GT  // >
	LTE // <=
	GTE // >=

	// Operators — string / list
	CONCAT    // + (overloaded; context-resolved in parser)
	CONCAT_OP // || (GQL string concatenation)
	TILDE_EQ  // =~ (regex match)

	// Delimiters
	COMMA          // ,
	SEMICOLON      // ;
	LPAREN         // (
	RPAREN         // )
	LBRACKET       // [
	RBRACKET       // ]
	LBRACE         // {
	RBRACE         // }
	DOT            // .
	DOTDOT         // ..   (range in relationship patterns)
	COLON          // :    (label / type separator)
	PIPE           // |    (alternative relationship types)
	AMPERSAND      // &    (label boolean AND)
	BANG           // !    (label boolean NOT)
	ARROW_RIGHT    // ->   (directed relationship, right)
	ARROW_LEFT     // <-   (directed relationship, left)
	DASH           // -    (undirected / relationship body, same rune as MINUS — resolved by lexer context)
	BACKTICK_IDENT // `escaped identifier`

	// -------------------------------------------------------------------------
	// Reading clauses
	// -------------------------------------------------------------------------
	MATCH
	OPTIONAL
	WITH
	UNWIND
	CALL  // procedure call
	YIELD // CALL ... YIELD

	// -------------------------------------------------------------------------
	// Writing clauses
	// -------------------------------------------------------------------------
	CREATE
	MERGE
	SET
	DELETE
	DETACH
	REMOVE
	FOREACH

	// -------------------------------------------------------------------------
	// Projection / modifiers
	// -------------------------------------------------------------------------
	RETURN
	ORDER
	BY
	SKIP
	LIMIT
	DISTINCT
	AS
	ASCENDING
	ASC
	DESCENDING
	DESC

	// -------------------------------------------------------------------------
	// Subquery / composite
	// -------------------------------------------------------------------------
	UNION
	ALL
	EXISTS // EXISTS { ... } subquery pattern

	// -------------------------------------------------------------------------
	// Predicates / conditions
	// -------------------------------------------------------------------------
	WHERE
	AND
	OR
	XOR
	NOT
	IN
	IS
	STARTS
	ENDS
	CONTAINS
	CASE
	WHEN
	THEN
	ELSE
	END

	// -------------------------------------------------------------------------
	// Path functions / quantifiers
	// -------------------------------------------------------------------------
	SHORTESTPATH
	ALLSHORTESTPATHS
	ANY    // list/path quantifier
	NONE   // list/path quantifier
	SINGLE // list/path quantifier — list quantifier "SINGLE(x IN list WHERE ...)"
	FILTER // deprecated but still in use: FILTER(x IN list WHERE ...)

	// -------------------------------------------------------------------------
	// Literals with keyword form
	// -------------------------------------------------------------------------
	COUNT   // COUNT(*), COUNT(DISTINCT ...)
	COLLECT // COLLECT { } subquery expression (Neo4j 5+)

	// -------------------------------------------------------------------------
	// ON clause (used in MERGE)
	// -------------------------------------------------------------------------
	ON
	MATCH_KW // ON MATCH SET  (the MATCH inside ON MATCH is the same token as MATCH above)

	// -------------------------------------------------------------------------
	// Load data
	// -------------------------------------------------------------------------
	LOAD
	CSV
	FROM
	HEADERS

	// -------------------------------------------------------------------------
	// Show / admin (openCypher extensions widely supported)
	// -------------------------------------------------------------------------
	SHOW
	INDEXES
	CONSTRAINTS
	PROCEDURES
	DATABASES
	DATABASE

	// -------------------------------------------------------------------------
	// Type system keywords
	// -------------------------------------------------------------------------
	BOOLEAN
	INTEGER
	FLOAT_KW  // FLOAT as a type keyword (not the literal)
	STRING_KW // STRING as a type keyword
	DATE
	TIME
	DATETIME
	LOCALDATETIME
	LOCALTIME
	DURATION
	POINT
	NODE
	RELATIONSHIP
	MAP
	LIST
	PATH
	GRAPH
	NOTHING
	ANY_KW // ANY as a type (not the quantifier) — see openCypher type system

	// -------------------------------------------------------------------------
	// Namespace keyword
	// -------------------------------------------------------------------------
	NAMESPACE // for procedure/function qualified names: apoc.util.sleep

	// -------------------------------------------------------------------------
	// Cypher 25 clause keywords
	// -------------------------------------------------------------------------
	FINISH

	// -------------------------------------------------------------------------
	// Subquery / transaction keywords (Neo4j 5+)
	// -------------------------------------------------------------------------
	CONCURRENT   // CONCURRENT
	TRANSACTIONS // TRANSACTIONS
	OF           // OF
	ROWS         // ROWS

)