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Better ExpandJoin phase using flat-joins
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94 changes: 40 additions & 54 deletions
94
quill-sql-portable/src/main/scala/io/getquill/sql/norm/ExpandJoin.scala
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,58 +1,44 @@ | ||
| package io.getquill.context.sql.norm | ||
| package io.getquill.sql.norm | ||
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| import io.getquill.ast._ | ||
| import io.getquill.norm.BetaReduction | ||
| import io.getquill.norm.Normalize | ||
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| /** | ||
| * This phase expands inner joins adding the correct aliases so they will function. Unfortunately, | ||
| * since it introduces aliases into the clauses that don't actually exist in the inner expressions, | ||
| * it is not technically type-safe but will not result in a Quat error since Quats cannot check | ||
| * for Ident scoping. For a better implementation, that uses a well-typed FlatMap/FlatJoin cascade, have | ||
| * a look here: | ||
| * [[https://gist.github.com/deusaquilus/dfb42880656df12779a0afd4f20ef1bb Better Typed ExpandJoin which uses FlatMap/FlatJoin]] | ||
| * | ||
| * The reason the above implementation is not currently used is because `ExpandNestedQueries` does not | ||
| * yet use Quat fields for expansion. Once this is changed, using that implementation here | ||
| * should be reconsidered. | ||
| */ | ||
| object ExpandJoin { | ||
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| def apply(q: Ast) = expand(q, None) | ||
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| def expand(q: Ast, id: Option[Ident]) = | ||
| Transform(q) { | ||
| case q @ Join(_, _, _, Ident(a, _), Ident(b, _), _) => // Ident a and Ident b should have the same Quat, could add an assertion for that | ||
| val (qr, tuple) = expandedTuple(q) | ||
| Map(qr, id.getOrElse(Ident(s"$a$b", q.quat)), tuple) | ||
| } | ||
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| private def expandedTuple(q: Join): (Join, Tuple) = | ||
| q match { | ||
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| case Join(t, a: Join, b: Join, tA, tB, o) => | ||
| val (ar, at) = expandedTuple(a) | ||
| val (br, bt) = expandedTuple(b) | ||
| val or = BetaReduction(o, tA -> at, tB -> bt) | ||
| (Join(t, ar, br, tA, tB, or), Tuple(List(at, bt))) | ||
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| case Join(t, a: Join, b, tA, tB, o) => | ||
| val (ar, at) = expandedTuple(a) | ||
| val or = BetaReduction(o, tA -> at) | ||
| (Join(t, ar, b, tA, tB, or), Tuple(List(at, tB))) | ||
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| case Join(t, a, b: Join, tA, tB, o) => | ||
| val (br, bt) = expandedTuple(b) | ||
| val or = BetaReduction(o, tB -> bt) | ||
| (Join(t, a, br, tA, tB, or), Tuple(List(tA, bt))) | ||
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| case q @ Join(t, a, b, tA, tB, on) => | ||
| (Join(t, nestedExpand(a, tA), nestedExpand(b, tB), tA, tB, on), Tuple(List(tA, tB))) | ||
| } | ||
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| private def nestedExpand(q: Ast, id: Ident) = | ||
| Normalize(expand(q, Some(id))) match { | ||
| case Map(q, _, _) => q | ||
| case q => q | ||
| object ExpandJoin extends StatelessTransformer { | ||
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| object ExcludedFromNesting { | ||
| def unapply(ast: Ast) = | ||
| ast match { | ||
| case _: Entity => true | ||
| case _: Infix => true | ||
| case _: FlatJoin => true | ||
| case _ => false | ||
| } | ||
| } | ||
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| override def apply(e: Query): Query = { | ||
| e match { | ||
| // Need to nest any map/flatMap clauses found in the `query` slot of a FlatMap or | ||
| // Verifier will cause Found an `ON` table reference of a table that is not available when they are | ||
| // found in this position. | ||
| case fm: FlatMap => | ||
| super.apply(fm) match { | ||
| case fm @ FlatMap(ExcludedFromNesting(), _, _) => fm | ||
| case FlatMap(ent, alias, body) => | ||
| FlatMap(Nested(ent), alias, body) | ||
| case other => | ||
| throw new IllegalArgumentException(s"Result of a flatMap reduction $fm needs to be a flatMap. It was $other.") | ||
| } | ||
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| // Note that quats in iA, iB shuold not need to change since this is a just a re-wrapping | ||
| case Join(typ, a, b, iA, iB, on) => | ||
| val a1 = | ||
| apply(a) match { | ||
| case v @ ExcludedFromNesting() => v | ||
| case other => Nested(other) | ||
| } | ||
| val b1 = apply(b) | ||
| FlatMap(a1, iA, Map(FlatJoin(typ, b1, iB, on), iB, Tuple(List(iA, iB)))) | ||
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| case _ => super.apply(e) | ||
| } | ||
| } | ||
| } | ||
| } |
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2 changes: 1 addition & 1 deletion
2
quill-sql/src/test/scala/io/getquill/context/sql/norm/ExpandJoinSpec.scala
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