SQLAST.kt

sealed class SqlStatement

// SELECT statement
data class Select(
    val selectList: SelectList,
    val tableReference: TableReference,
    val whereCondition: Condition? = null,
    val groupBy: ColumnList? = null,
    val orderBy: OrderList? = null,
    val orderByOption: OrderByOption? = null,
    val limit: Int? = null
) : SqlStatement()

// INSERT statement
data class Insert(
    val table: Identifier,
    val columns: ColumnList,
    val values: ValueList
) : SqlStatement()

// UPDATE statement
data class Update(
    val table: Identifier,
    val assignments: List<ColumnAssignment>,
    val whereCondition: Condition? = null
) : SqlStatement()

// DELETE statement
data class Delete(
    val table: Identifier,
    val whereCondition: Condition? = null
) : SqlStatement()

// TABLE REFERENCES (supports JOINs)
data class TableReference(
    val table: Identifier,
    val join: Join? = null
)

// JOIN structure
data class Join(
    val table: Identifier,
    val condition: Condition
)

// SELECT LIST (* or column list)
sealed class SelectList
object SelectAll : SelectList()
data class SelectColumns(val columns: ColumnList) : SelectList()

// COLUMN LIST
data class ColumnList(val columns: List<Identifier>)

// ORDER BY Options
enum class OrderByOption { ASC, DESC }
data class OrderList(val columns: List<Identifier>)

// COLUMN ASSIGNMENT (for UPDATE)
data class ColumnAssignment(val column: Identifier, val value: Value)

// CONDITIONS (WHERE Clause)
sealed class Condition
data class ComparisonCondition(
    val left: Expression,
    val operator: ComparisonOperator,
    val right: Expression
) : Condition()

data class LogicalCondition(
    val left: Condition,
    val operator: LogicalOperator,
    val right: Condition
) : Condition()

data class ParenthesizedCondition(val condition: Condition) : Condition()

// VALUE LIST (for INSERT)
data class ValueList(val values: List<Value>)

// VALUE (can be literal or expression)
sealed class Value
data class SqlLiteral(val value: String) : Value()  // 'John', 12, NULL
data class ExpressionValue(val expression: Expression) : Value()

// EXPRESSION (identifiers, literals, functions, and operations)
sealed class Expression
data class Identifier(val name: String) : Expression() // Column or table names
data class FunctionCall(val name: String, val arguments: List<Expression>) : Expression()
data class BinaryExpression(
    val left: Expression,
    val operator: Operator,
    val right: Expression
) : Expression()

// SQL OPERATORS
sealed class Operator
enum class ComparisonOperator { EQUALS, NOT_EQUALS, GREATER, LESS, GREATER_EQUALS, LESS_EQUALS }
enum class LogicalOperator { AND, OR, NOT }
enum class ArithmeticOperator { ADD, MULTIPLY, DIVIDE }

// SQL LITERAL TYPES
sealed class SqlLiteralType
data class StringLiteral(val value: String) : SqlLiteralType()  // "John"
data class NumberLiteral(val value: Double) : SqlLiteralType()  // 123.45
object NullLiteral : SqlLiteralType()  // NULL