gudusoft.gsqlparser.ir.semantic

Class OutputColumn

Object

gudusoft.gsqlparser.ir.semantic.OutputColumn

public final class OutputColumn
extends Object

One projected column in the SELECT list. sources is the list of input columns this output depends on; derived distinguishes a direct column reference (e.g. SELECT id) from a computed expression (e.g. SELECT salary*2 AS doubled or SELECT a.x + a.y); aggregate marks the output as the result of an aggregate function call (e.g. COUNT(*), SUM(salary)); windowSpec (slice 13) carries PARTITION BY / OVER ORDER BY refs when the projection is a window function.

Slice 4 introduced derived; slice 6 added aggregate and lifted the empty-sources restriction for aggregates only (e.g. COUNT(*) has no column refs); slice 13 added windowSpec and lifts the empty-sources restriction for window functions (e.g. ROW_NUMBER() OVER (...) has no column refs).

Note on flag propagation: derived, aggregate, and windowSpec are local to a single statement's output. They are not propagated transitively. If a CTE defines total = SUM(salary), that CTE's output has aggregate=true; an outer query that re-projects the CTE's total column (SELECT total FROM cte) is a direct reference and so the outer's output has aggregate=false (and derived=false). Consumers that need a transitive view should walk SemanticProgram.getLineage() and inspect each upstream OutputColumn.

Window-function invariant (slice 13): when windowSpec != null, aggregate MUST be false. Window functions are row-preserving (analytic), not row-collapsing, so the per-output aggregate flag stays false even when the window function is a name that overlaps with an aggregate (e.g. AVG(salary) OVER (...)). The constructor enforces this invariant.

Constructor Summary

Constructors

Constructor and Description
OutputColumn(String name, boolean derived, boolean aggregate, List<ColumnRef> sources) Backwards-compatible constructor delegating to the 5-arg form with windowSpec=null.
OutputColumn(String name, boolean derived, boolean aggregate, List<ColumnRef> sources, WindowSpec windowSpec)

Method Summary

Modifier and Type	Method and Description
String	getName()
List<ColumnRef>	getSources()
WindowSpec	getWindowSpec() Per-output analytic dependencies (slice 13).
boolean	isAggregate() true when the projection is an aggregate function call (COUNT, SUM, AVG, MIN, MAX, etc.).
boolean	isDerived() true when the projection is an expression rather than a direct column reference.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

OutputColumn

public OutputColumn(String name,
                    boolean derived,
                    boolean aggregate,
                    List<ColumnRef> sources)

Backwards-compatible constructor delegating to the 5-arg form with windowSpec=null. Slice 13 added the 5-arg constructor; this overload preserves source-compatibility for downstream callers that were already using OutputColumn from a published version of the library.

OutputColumn

public OutputColumn(String name,
                    boolean derived,
                    boolean aggregate,
                    List<ColumnRef> sources,
                    WindowSpec windowSpec)

Method Detail

getName

public String getName()

isDerived

public boolean isDerived()

true when the projection is an expression rather than a direct column reference.

isAggregate

public boolean isAggregate()

true when the projection is an aggregate function call (COUNT, SUM, AVG, MIN, MAX, etc.). Always implies isDerived(). Always false when getWindowSpec() is non-null (window functions are row-preserving).

getSources

public List<ColumnRef> getSources()

getWindowSpec

public WindowSpec getWindowSpec()

Per-output analytic dependencies (slice 13). Non-null iff this projection is a window function (e.g. FUNC(arg) OVER (...)); null otherwise.