Rex abstract base classes

partiql · Nov 27, 2024 · 7b0857b · 7b0857b
1 parent 7886f19
commit 7b0857b
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diff --git a/partiql-eval/src/main/kotlin/org/partiql/eval/internal/compiler/StandardCompiler.kt b/partiql-eval/src/main/kotlin/org/partiql/eval/internal/compiler/StandardCompiler.kt
@@ -85,7 +85,7 @@ import org.partiql.plan.rex.Rex
 import org.partiql.plan.rex.RexArray
 import org.partiql.plan.rex.RexBag
 import org.partiql.plan.rex.RexCall
-import org.partiql.plan.rex.RexCallDynamic
+import org.partiql.plan.rex.RexDispatch
 import org.partiql.plan.rex.RexCase
 import org.partiql.plan.rex.RexCast
 import org.partiql.plan.rex.RexCoalesce
@@ -338,7 +338,7 @@ internal class StandardCompiler(strategies: List<Strategy>) : PartiQLCompiler {
             return ExprBag(values)
         }
 
-        override fun visitCallDynamic(rex: RexCallDynamic, ctx: Unit): ExprValue {
+        override fun visitCallDynamic(rex: RexDispatch, ctx: Unit): ExprValue {
             // Check candidate arity for uniformity
             var arity: Int = -1
             val name = rex.getName()
@@ -401,7 +401,7 @@ internal class StandardCompiler(strategies: List<Strategy>) : PartiQLCompiler {
         }
 
         override fun visitLit(rex: RexLit, ctx: Unit): ExprValue {
-            return ExprLit(rex.getValue())
+            return ExprLit(rex.getDatum())
         }
 
         override fun visitNullIf(rex: RexNullIf, ctx: Unit): ExprValue {
@@ -460,7 +460,7 @@ internal class StandardCompiler(strategies: List<Strategy>) : PartiQLCompiler {
         }
 
         override fun visitSubquery(rex: RexSubquery, ctx: Unit): ExprValue {
-            val rel = compile(rex.getRel(), ctx)
+            val rel = compile(rex.getInput(), ctx)
             val constructor = compile(rex.getConstructor(), ctx)
             return when (rex.asScalar()) {
                 true -> ExprSubquery(rel, constructor)

diff --git a/partiql-plan/README.md b/partiql-plan/README.md
@@ -0,0 +1,32 @@
+# partiql-plan
+
+## Classes
+
+* Operator
+* Rel
+* Rex
+
+## Visitors
+
+* Visitor
+* Rewriter
+
+## Design
+
+For the rule and strategy patterns to work, we need to model classes whose children have a stable ordering;
+so we have defined an abstract base class for all operators which holds children and controls the access to them.
+We use base implementations for state management and enforcing children ordering; however we use interfaces for the
+top-level of each domain. The abstract bases can be extended, and the operator/rel/rex interfaces can be implemented
+directly.
+
+Why interfaces for top-level domain entities and not abstract base classes?
+
+* We don’t want to force materialization of children (consider wrapping a serde class)
+* We don’t want to force holding state (aka having to call super constructors)
+* The operator/rel/rex should be flexible for extension and the interface is the most open-ended / non-prescriptive.
+
+Why abstract base classes for individual operators and not interfaces?
+
+* Enforce children ordering is the primary reason; also can memoize children.
+* Hold state such as mutable tags and computed types.
+* We want the standard operators to be prescriptive but not limiting.
diff --git a/partiql-plan/src/main/java/org/partiql/plan/Visitor.kt b/partiql-plan/src/main/java/org/partiql/plan/Visitor.kt
@@ -19,7 +19,7 @@ import org.partiql.plan.rel.RelUnpivot
 import org.partiql.plan.rex.RexArray
 import org.partiql.plan.rex.RexBag
 import org.partiql.plan.rex.RexCall
-import org.partiql.plan.rex.RexCallDynamic
+import org.partiql.plan.rex.RexDispatch
 import org.partiql.plan.rex.RexCase
 import org.partiql.plan.rex.RexCast
 import org.partiql.plan.rex.RexCoalesce
@@ -101,7 +101,7 @@ public interface Visitor<R, C> {
 
     public fun visitCall(rex: RexCall, ctx: C): R = defaultVisit(rex, ctx)
 
-    public fun visitCallDynamic(rex: RexCallDynamic, ctx: C): R = defaultVisit(rex, ctx)
+    public fun visitCallDynamic(rex: RexDispatch, ctx: C): R = defaultVisit(rex, ctx)
 
     public fun visitCase(rex: RexCase, ctx: C): R = defaultVisit(rex, ctx)
 

diff --git a/partiql-plan/src/main/java/org/partiql/plan/rel/RelAggregate.java b/partiql-plan/src/main/java/org/partiql/plan/rel/RelAggregate.java
@@ -6,7 +6,6 @@
 import org.partiql.plan.rex.Rex;
 import org.partiql.spi.function.Aggregation;
 
-import java.util.Collection;
 import java.util.List;
 
 /**
@@ -16,42 +15,33 @@ public abstract class RelAggregate extends RelBase {
 
     // TODO GROUP STRATEGY: https://github.com/partiql/partiql-lang-kotlin/issues/1664
 
-    private final RelType type = null;
-    private List<Operator> children = null;
-
     /**
      * @return the input (child 0)
      */
     @NotNull
     public abstract Rel getInput();
 
     @NotNull
-    public abstract Collection<Measure> getMeasures();
+    public abstract List<Measure> getMeasures();
 
     @NotNull
-    public abstract Collection<Rex> getGroups();
+    public abstract List<Rex> getGroups();
 
     @NotNull
     @Override
-    public final RelType getType() {
-        if (type == null) {
-            throw new UnsupportedOperationException("Derive type is not implemented");
-        }
-        return type;
+    protected final RelType type() {
+        throw new UnsupportedOperationException("Derive type is not implemented");
     }
 
     @NotNull
     @Override
-    public final List<Operator> getChildren() {
-        if (children == null) {
-            Rel c0 = getInput();
-            children = List.of(c0);
-        }
-        return children;
+    protected final List<Operator> children() {
+        Rel c0 = getInput();
+        return List.of(c0);
     }
 
     @Override
-    public <R, C> R accept(Visitor<R, C> visitor, C ctx) {
+    public <R, C> R accept(@NotNull Visitor<R, C> visitor, C ctx) {
         return visitor.visitAggregate(this, ctx);
     }
 
@@ -61,10 +51,10 @@ public <R, C> R accept(Visitor<R, C> visitor, C ctx) {
     public static class Measure {
 
         private final Aggregation agg;
-        private final Collection<Rex> args;
+        private final List<Rex> args;
         private final Boolean distinct;
 
-        public Measure(Aggregation agg, Collection<Rex> args, Boolean distinct) {
+        public Measure(Aggregation agg, List<Rex> args, Boolean distinct) {
             this.agg = agg;
             this.args = args;
             this.distinct = distinct;
@@ -76,7 +66,7 @@ public Aggregation getAgg() {
         }
 
         @NotNull
-        public Collection<Rex> getArgs() {
+        public List<Rex> getArgs() {
             return args;
         }
 

diff --git a/partiql-plan/src/main/java/org/partiql/plan/rel/RelBase.java b/partiql-plan/src/main/java/org/partiql/plan/rel/RelBase.java
@@ -3,12 +3,16 @@
 import org.jetbrains.annotations.NotNull;
 import org.partiql.plan.Operator;
 
+import java.util.List;
+
 /**
  * Abstract base class for all relational operators.
  */
 public abstract class RelBase implements Rel {
 
     private int tag = 0;
+    private RelType type;
+    private List<Operator> children;
 
     @Override
     public int getTag() {
@@ -22,7 +26,39 @@ public void setTag(int tag) {
 
     @NotNull
     @Override
-    public Operator getChild(int index) {
-        return getChildren().get(index);
+    public final RelType getType() {
+        if (type == null) {
+            type = type();
+        }
+        return type;
+    }
+
+    @NotNull
+    @Override
+    public final Operator getChild(int index) {
+        return children.get(index);
     }
+
+    @NotNull
+    @Override
+    public final List<Operator> getChildren() {
+        if (children == null) {
+            children = children();
+        }
+        return children;
+    }
+
+    /**
+     * PROTECTED (could also be package private atm).
+     *
+     * @return computed type.
+     */
+    protected abstract RelType type();
+
+    /**
+     * PROTECTED (could also be package private atm).
+     *
+     * @return computed children.
+     */
+    protected abstract List<Operator> children();
 }
diff --git a/partiql-plan/src/main/java/org/partiql/plan/rel/RelCorrelate.java b/partiql-plan/src/main/java/org/partiql/plan/rel/RelCorrelate.java
@@ -12,9 +12,6 @@
  */
 public abstract class RelCorrelate extends RelBase {
 
-    private final RelType type = null;
-    private List<Operator> children = null;
-
     /**
      * @return the left input (child 0)
      */
@@ -32,26 +29,20 @@ public abstract class RelCorrelate extends RelBase {
 
     @NotNull
     @Override
-    public final RelType getType() {
-        if (type == null) {
-            throw new UnsupportedOperationException("Derive type is not implemented");
-        }
-        return type;
+    protected final RelType type() {
+        throw new UnsupportedOperationException("Derive type is not implemented");
     }
 
     @NotNull
     @Override
-    public final List<Operator> getChildren() {
-        if (children == null) {
-            Rel c0 = getLeft();
-            Rel c1 = getRight();
-            children = List.of(c0, c1);
-        }
-        return children;
+    protected final List<Operator> children() {
+        Rel c0 = getLeft();
+        Rel c1 = getRight();
+        return List.of(c0, c1);
     }
 
     @Override
-    public <R, C> R accept(Visitor<R, C> visitor, C ctx) {
+    public <R, C> R accept(@NotNull Visitor<R, C> visitor, C ctx) {
         return visitor.visitCorrelate(this, ctx);
     }
 }
diff --git a/partiql-plan/src/main/java/org/partiql/plan/rel/RelDistinct.java b/partiql-plan/src/main/java/org/partiql/plan/rel/RelDistinct.java
@@ -11,9 +11,6 @@
  */
 public abstract class RelDistinct extends RelBase {
 
-    private final RelType type = null;
-    private List<Operator> children = null;
-
     /**
      * @return input rel (child 0)
      */
@@ -22,25 +19,19 @@ public abstract class RelDistinct extends RelBase {
 
     @NotNull
     @Override
-    public final RelType getType() {
-        if (type == null) {
-            throw new UnsupportedOperationException("Derive type is not implemented");
-        }
-        return type;
+    protected final RelType type() {
+        throw new UnsupportedOperationException("Derive type is not implemented");
     }
 
     @NotNull
     @Override
-    public final List<Operator> getChildren() {
-        if (children == null) {
-            Rel c0 = getInput();
-            children = List.of(c0);
-        }
-        return children;
+    protected final List<Operator> children() {
+        Rel c0 = getInput();
+        return List.of(c0);
     }
 
     @Override
-    public <R, C> R accept(Visitor<R, C> visitor, C ctx) {
+    public <R, C> R accept(@NotNull Visitor<R, C> visitor, C ctx) {
         return visitor.visitDistinct(this, ctx);
     }
 }
diff --git a/partiql-plan/src/main/java/org/partiql/plan/rel/RelExcept.java b/partiql-plan/src/main/java/org/partiql/plan/rel/RelExcept.java
@@ -11,9 +11,6 @@
  */
 public abstract class RelExcept extends RelBase {
 
-    private final RelType type = null;
-    private List<Operator> children = null;
-
     /**
      * @return true if ALL else DISTINCT.
      */
@@ -33,26 +30,20 @@ public abstract class RelExcept extends RelBase {
 
     @NotNull
     @Override
-    public final RelType getType() {
-        if (type == null) {
-            throw new UnsupportedOperationException("Derive type is not implemented");
-        }
-        return type;
+    protected final RelType type() {
+        throw new UnsupportedOperationException("Derive type is not implemented");
     }
 
     @NotNull
     @Override
-    public final List<Operator> getChildren() {
-        if (children == null) {
-            Rel c0 = getLeft();
-            Rel c1 = getRight();
-            children = List.of(c0, c1);
-        }
-        return children;
+    protected final List<Operator> children() {
+        Rel c0 = getLeft();
+        Rel c1 = getRight();
+        return List.of(c0, c1);
     }
 
     @Override
-    public <R, C> R accept(Visitor<R, C> visitor, C ctx) {
+    public <R, C> R accept(@NotNull Visitor<R, C> visitor, C ctx) {
         return visitor.visitExcept(this, ctx);
     }
 }