feat(catalog): add DependencyAnalysis and referencesRelation

src/main/kotlin/kestrel/catalog/DependencyAnalysis.kt

@@ -0,0 +1,123 @@
+package kestrel.catalog
+
+import kestrel.sql.ast.BetweenExpression
+import kestrel.sql.ast.BinaryExpression
+import kestrel.sql.ast.CallExpression
+import kestrel.sql.ast.CaseExpression
+import kestrel.sql.ast.CastExpression
+import kestrel.sql.ast.CollateExpression
+import kestrel.sql.ast.ColumnExpression
+import kestrel.sql.ast.CommonTableExpression
+import kestrel.sql.ast.CurrentValueExpression
+import kestrel.sql.ast.ExistsExpression
+import kestrel.sql.ast.Expression
+import kestrel.sql.ast.ExpressionProjection
+import kestrel.sql.ast.FrameBound
+import kestrel.sql.ast.FromItem
+import kestrel.sql.ast.FunctionExpression
+import kestrel.sql.ast.InExpression
+import kestrel.sql.ast.InSubqueryExpression
+import kestrel.sql.ast.IsNullExpression
+import kestrel.sql.ast.JoinClause
+import kestrel.sql.ast.LikeExpression
+import kestrel.sql.ast.LiteralExpression
+import kestrel.sql.ast.MergeActionExpression
+import kestrel.sql.ast.NextValueExpression
+import kestrel.sql.ast.ParameterExpression
+import kestrel.sql.ast.Projection
+import kestrel.sql.ast.QueryStatement
+import kestrel.sql.ast.ScalarSubqueryExpression
+import kestrel.sql.ast.SelectStatement
+import kestrel.sql.ast.SetOperationStatement
+import kestrel.sql.ast.StarProjection
+import kestrel.sql.ast.SubquerySource
+import kestrel.sql.ast.TableSource
+import kestrel.sql.ast.UnaryExpression
+import kestrel.sql.ast.WindowExpression
+import kestrel.sql.ast.WithQuery
+
+/**
+ * Walks a view's defining query looking for a relation name anywhere it could appear:
+ * FROM/JOIN targets, derived tables, CTE bodies, set-operation branches, and every
+ * subquery expression (scalar/EXISTS/IN) nested inside WHERE/HAVING/projection/GROUP BY.
+ * Used by [Catalog] to find what would break (RESTRICT) or need to cascade (CASCADE)
+ * when a table or view is dropped.
+ */
+internal object DependencyAnalysis {
+    fun referencesRelation(query: QueryStatement, name: String): Boolean = when (query) {
+        is SelectStatement -> referencesInSelect(query, name)
+        is SetOperationStatement -> referencesRelation(query.left, name) || referencesRelation(query.right, name)
+        is WithQuery -> query.ctes.any { referencesInCte(it, name) } || referencesRelation(query.body, name)
+    }
+
+    private fun referencesInCte(cte: CommonTableExpression, name: String): Boolean =
+        referencesRelation(cte.query, name)
+
+    private fun referencesInSelect(select: SelectStatement, name: String): Boolean {
+        if (referencesFromItem(select.from, name)) return true
+        if (select.joins.any { referencesJoin(it, name) }) return true
+        if (select.where?.let { referencesInExpression(it, name) } == true) return true
+        if (select.groupBy.any { referencesInExpression(it, name) }) return true
+        if (select.having?.let { referencesInExpression(it, name) } == true) return true
+        if (select.distinctOn.any { referencesInExpression(it, name) }) return true
+        return referencesInProjection(select.projection, name)
+    }
+
+    private fun referencesJoin(join: JoinClause, name: String): Boolean =
+        referencesFromItem(join.from, name) || (join.on?.let { referencesInExpression(it, name) } == true)
+
+    private fun referencesFromItem(item: FromItem, name: String): Boolean = when (item) {
+        is TableSource -> item.name.equals(name, ignoreCase = true)
+        is SubquerySource -> referencesRelation(item.select, name)
+    }
+
+    private fun referencesInProjection(projection: Projection, name: String): Boolean = when (projection) {
+        is StarProjection -> false
+        is ExpressionProjection -> projection.items.any { referencesInExpression(it.expression, name) }
+    }
+
+    private fun referencesInExpression(expression: Expression, name: String): Boolean = when (expression) {
+        is ScalarSubqueryExpression -> referencesRelation(expression.select, name)
+        is ExistsExpression -> referencesRelation(expression.select, name)
+        is InSubqueryExpression ->
+            referencesRelation(expression.select, name) || referencesInExpression(expression.operand, name)
+        is BinaryExpression -> referencesInExpression(expression.left, name) || referencesInExpression(expression.right, name)
+        is UnaryExpression -> referencesInExpression(expression.operand, name)
+        is CallExpression -> expression.arguments.any { referencesInExpression(it, name) }
+        is IsNullExpression -> referencesInExpression(expression.operand, name)
+        is InExpression ->
+            referencesInExpression(expression.operand, name) || expression.values.any { referencesInExpression(it, name) }
+        is BetweenExpression ->
+            referencesInExpression(expression.operand, name) ||
+                referencesInExpression(expression.low, name) ||
+                referencesInExpression(expression.high, name)
+        is LikeExpression ->
+            referencesInExpression(expression.operand, name) || referencesInExpression(expression.pattern, name)
+        is CaseExpression ->
+            (expression.operand?.let { referencesInExpression(it, name) } ?: false) ||
+                expression.branches.any {
+                    referencesInExpression(it.condition, name) || referencesInExpression(it.result, name)
+                } ||
+                (expression.elseExpression?.let { referencesInExpression(it, name) } ?: false)
+        is CastExpression -> referencesInExpression(expression.operand, name)
+        is CollateExpression -> referencesInExpression(expression.operand, name)
+        is FunctionExpression ->
+            (expression.argument?.let { referencesInExpression(it, name) } ?: false) ||
+                (expression.separator?.let { referencesInExpression(it, name) } ?: false) ||
+                expression.orderBy.any { referencesInExpression(it.expression, name) } ||
+                (expression.filter?.let { referencesInExpression(it, name) } ?: false)
+        is WindowExpression ->
+            (expression.argument?.let { referencesInExpression(it, name) } ?: false) ||
+                (expression.offset?.let { referencesInExpression(it, name) } ?: false) ||
+                (expression.defaultValue?.let { referencesInExpression(it, name) } ?: false) ||
+                (expression.frame?.start?.let { referencesInFrameBound(it, name) } ?: false) ||
+                (expression.frame?.end?.let { referencesInFrameBound(it, name) } ?: false) ||
+                expression.partitionBy.any { referencesInExpression(it, name) } ||
+                expression.orderBy.any { referencesInExpression(it.expression, name) }
+        is ColumnExpression, is LiteralExpression, is NextValueExpression, is CurrentValueExpression,
+        is MergeActionExpression, is ParameterExpression -> false
+    }
+
+    private fun referencesInFrameBound(bound: FrameBound, name: String): Boolean =
+        bound.offset?.let { referencesInExpression(it, name) } ?: false
+}