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calasql-query_3.0.1.5.source-code.CompoundSelect.scala Maven / Gradle / Ivy
package scalasql.query
import scalasql.core.SqlStr.{Renderable, SqlStringSyntax}
import scalasql.core.{Context, DialectTypeMappers, LiveExprs, Queryable, Expr, SqlStr}
/**
* A SQL `SELECT` query, with
* `ORDER BY`, `LIMIT`, `OFFSET`, or `UNION` clauses
*/
class CompoundSelect[Q, R](
val lhs: SimpleSelect[Q, R],
val compoundOps: Seq[CompoundSelect.Op[Q, R]],
val orderBy: Seq[OrderBy],
val limit: Option[Int],
val offset: Option[Int]
)(implicit val qr: Queryable.Row[Q, R], val dialect: DialectTypeMappers)
extends Select.Proxy[Q, R] {
protected def copy[Q, R](
lhs: SimpleSelect[Q, R] = this.lhs,
compoundOps: Seq[CompoundSelect.Op[Q, R]] = this.compoundOps,
orderBy: Seq[OrderBy] = this.orderBy,
limit: Option[Int] = this.limit,
offset: Option[Int] = this.offset
)(implicit qr: Queryable.Row[Q, R]) = newCompoundSelect(lhs, compoundOps, orderBy, limit, offset)
override protected def expr = Joinable.toFromExpr(lhs)._2
protected def selectToSimpleSelect() = this.subquery
override def map[Q2, R2](f: Q => Q2)(implicit qr2: Queryable.Row[Q2, R2]): Select[Q2, R2] = {
(lhs, compoundOps) match {
case (s: SimpleSelect[Q, R], Nil) =>
val mapped = s.map(f)
copy[Q2, R2](mapped, Nil, orderBy, limit, offset)
case _ => selectToSimpleSelect().map(f)
}
}
override def filter(f: Q => Expr[Boolean]): Select[Q, R] = {
(lhs, compoundOps) match {
case (s: SimpleSelect[Q, R], Nil) =>
copy(Select.toSimpleFrom(s.filter(f)), compoundOps, orderBy, limit, offset)
case _ => selectToSimpleSelect().filter(f)
}
}
override def sortBy(f: Q => Expr[?]) = {
val newOrder = Seq(OrderBy(f(expr), None, None))
if (limit.isEmpty && offset.isEmpty) copy(orderBy = newOrder ++ orderBy)
else newCompoundSelect(selectToSimpleSelect(), compoundOps, newOrder, None, None)
}
override def asc: Select[Q, R] =
copy(orderBy = orderBy.take(1).map(_.copy(ascDesc = Some(AscDesc.Asc))) ++ orderBy.drop(1))
override def desc: Select[Q, R] =
copy(orderBy = orderBy.take(1).map(_.copy(ascDesc = Some(AscDesc.Desc))) ++ orderBy.drop(1))
override def nullsFirst: Select[Q, R] =
copy(orderBy = orderBy.take(1).map(_.copy(nulls = Some(Nulls.First))) ++ orderBy.drop(1))
override def nullsLast: Select[Q, R] =
copy(orderBy = orderBy.take(1).map(_.copy(nulls = Some(Nulls.Last))) ++ orderBy.drop(1))
override def compound0(op: String, other: Select[Q, R]) = {
val op2 = CompoundSelect.Op(op, Select.toSimpleFrom(other))
if (orderBy.isEmpty && limit.isEmpty && offset.isEmpty)
copy(compoundOps = compoundOps ++ Seq(op2))
else newCompoundSelect(selectToSimpleSelect(), Seq(op2), Nil, None, None)
}
override def drop(n: Int): Select[Q, R] =
copy(offset = Some(offset.getOrElse(0) + n), limit = limit.map(_ - n))
override def take(n: Int): Select[Q, R] = copy(limit = Some(limit.fold(n)(math.min(_, n))))
override protected def selectRenderer(prevContext: Context): SubqueryRef.Wrapped.Renderer =
new CompoundSelect.Renderer(this, prevContext)
override protected def selectExprAliases(prevContext: Context) = {
SubqueryRef.Wrapped.exprAliases(lhs, prevContext)
}
}
object CompoundSelect {
case class Op[Q, R](op: String, rhs: SimpleSelect[Q, R])
class Renderer[Q, R](query: CompoundSelect[Q, R], prevContext: Context)
extends SubqueryRef.Wrapped.Renderer {
import query.dialect._
lazy val renderer = SimpleSelect.getRenderer(query.lhs, prevContext)
lazy val lhsExprAliases = SubqueryRef.Wrapped.exprAliases(query.lhs, prevContext)
lazy val context = renderer.context
.withExprNaming(renderer.context.exprNaming ++ lhsExprAliases)
lazy val sortOpt = SqlStr.flatten(orderToSqlStr(context))
lazy val limitOpt = SqlStr.flatten(SqlStr.opt(query.limit) { limit =>
sql" LIMIT $limit"
})
lazy val offsetOpt = SqlStr.flatten(SqlStr.opt(query.offset) { offset =>
sql" OFFSET $offset"
})
lazy val newReferencedExpressions = Seq(limitOpt, offsetOpt, sortOpt).flatMap(_.referencedExprs)
// For compound expressions that eliminate duplicate columns (i.e. UNION/INTERSECT/EXCEPT,
// everything except UNION ALL) we cannot eliminate dead columns as it affects whether
// columns are duplicates or not, and thus what final set of rows is returned
lazy val preserveAll = query.compoundOps.exists(_.op != "UNION ALL")
def render(liveExprs: LiveExprs) = {
val innerLiveExprs =
if (preserveAll) LiveExprs.none
else liveExprs.map(_ ++ newReferencedExpressions)
val lhsStr = renderer.render(innerLiveExprs)
val lhsExprIndices = lhsExprAliases.iterator.map(_._1).zipWithIndex.toMap
val innerLiveExprIndices = innerLiveExprs.values.map(_.flatMap(lhsExprIndices.get))
val compound = SqlStr.optSeq(query.compoundOps) { compoundOps =>
val compoundStrs = compoundOps.map { op =>
val rhsToSqlQuery = SimpleSelect.getRenderer(op.rhs, prevContext)
lazy val rhsExprAliases = SubqueryRef.Wrapped.exprAliases(op.rhs, prevContext)
// We match up the RHS SimpleSelect's exprAliases with the LHS SimpleSelect's
// exprAliases, because the expressions in the CompoundSelect's lhsMap correspond
// to those belonging to the LHS SimpleSelect, but we need the corresponding
// expressions belonging to the RHS SimpleSelect `liveExprs` analysis to work
val rhsInnerLiveExprs = rhsExprAliases.iterator.zipWithIndex.collect {
case ((k, v), i) if innerLiveExprIndices.fold(true)(_(i)) => k
}.toSet
sql" ${SqlStr.raw(op.op)} ${rhsToSqlQuery.render(new LiveExprs(Some(rhsInnerLiveExprs)))}"
}
SqlStr.join(compoundStrs)
}
lhsStr + compound + sortOpt + limitOpt + offsetOpt
}
def orderToSqlStr(newCtx: Context) =
CompoundSelect.orderToSqlStr(query.orderBy, newCtx, gap = true)
}
def orderToSqlStr(orderBys: Seq[OrderBy], newCtx: Context, gap: Boolean = false) = {
SqlStr.optSeq(orderBys) { orderBys =>
val orderStr = SqlStr.join(
orderBys.map { orderBy =>
val ascDesc = orderBy.ascDesc match {
case None => SqlStr.empty
case Some(AscDesc.Asc) => sql" ASC"
case Some(AscDesc.Desc) => sql" DESC"
}
val nulls = SqlStr.opt(orderBy.nulls) {
case Nulls.First => sql" NULLS FIRST"
case Nulls.Last => sql" NULLS LAST"
}
Renderable.renderSql(orderBy.expr)(newCtx) + ascDesc + nulls
},
SqlStr.commaSep
)
val prefix = if (gap) sql" ORDER BY " else sql"ORDER BY "
prefix + orderStr
}
}
}
