ES|QL: Remove Pipe (Processor) logic from ESQL-core (#108963)

Pipe logic is not used in ES|QL. 

This PR also moves some tests to ES|QL, making sure that they run using
the implementation that matter to us (eg. `esql...Add`/`Sub`... rather
than `esql.core...Add`/`Sub`...)

Author: luigidellaquila

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/expression/Expressions.java

@@ -7,18 +7,11 @@
 package org.elasticsearch.xpack.esql.core.expression;
 
 import org.elasticsearch.core.Tuple;
-import org.elasticsearch.xpack.esql.core.QlIllegalArgumentException;
-import org.elasticsearch.xpack.esql.core.expression.function.Function;
-import org.elasticsearch.xpack.esql.core.expression.gen.pipeline.AttributeInput;
-import org.elasticsearch.xpack.esql.core.expression.gen.pipeline.ConstantInput;
-import org.elasticsearch.xpack.esql.core.expression.gen.pipeline.Pipe;
 import org.elasticsearch.xpack.esql.core.type.DataTypes;
 
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.LinkedHashSet;
 import java.util.List;
-import java.util.Set;
 import java.util.function.Predicate;
 
 import static java.util.Collections.emptyList;
@@ -182,59 +175,6 @@ public static List<Tuple<Attribute, Expression>> aliases(List<? extends NamedExp
         return aliases;
     }
 
-    public static boolean hasReferenceAttribute(Collection<Attribute> output) {
-        for (Attribute attribute : output) {
-            if (attribute instanceof ReferenceAttribute) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    public static List<Attribute> onlyPrimitiveFieldAttributes(Collection<Attribute> attributes) {
-        List<Attribute> filtered = new ArrayList<>();
-        // add only primitives
-        // but filter out multi fields (allow only the top-level value)
-        Set<Attribute> seenMultiFields = new LinkedHashSet<>();
-
-        for (Attribute a : attributes) {
-            if (DataTypes.isUnsupported(a.dataType()) == false && DataTypes.isPrimitive(a.dataType())) {
-                if (a instanceof FieldAttribute fa) {
-                    // skip nested fields and seen multi-fields
-                    if (fa.isNested() == false && seenMultiFields.contains(fa.parent()) == false) {
-                        filtered.add(a);
-                        seenMultiFields.add(a);
-                    }
-                } else {
-                    filtered.add(a);
-                }
-            }
-        }
-
-        return filtered;
-    }
-
-    public static Pipe pipe(Expression e) {
-        if (e.foldable()) {
-            return new ConstantInput(e.source(), e, e.fold());
-        }
-        if (e instanceof NamedExpression ne) {
-            return new AttributeInput(e.source(), e, ne.toAttribute());
-        }
-        if (e instanceof Function f) {
-            return f.asPipe();
-        }
-        throw new QlIllegalArgumentException("Cannot create pipe for {}", e);
-    }
-
-    public static List<Pipe> pipe(List<Expression> expressions) {
-        List<Pipe> pipes = new ArrayList<>(expressions.size());
-        for (Expression e : expressions) {
-            pipes.add(pipe(e));
-        }
-        return pipes;
-    }
-
     public static String id(Expression e) {
         return Integer.toHexString(e.hashCode());
     }

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/expression/function/Function.java

@@ -9,8 +9,6 @@
 import org.elasticsearch.xpack.esql.core.expression.Expression;
 import org.elasticsearch.xpack.esql.core.expression.Expressions;
 import org.elasticsearch.xpack.esql.core.expression.Nullability;
-import org.elasticsearch.xpack.esql.core.expression.gen.pipeline.ConstantInput;
-import org.elasticsearch.xpack.esql.core.expression.gen.pipeline.Pipe;
 import org.elasticsearch.xpack.esql.core.tree.Source;
 
 import java.util.List;
@@ -26,8 +24,6 @@ public abstract class Function extends Expression {
 
     private final String functionName = getClass().getSimpleName().toUpperCase(Locale.ROOT);
 
-    private Pipe lazyPipe = null;
-
     // TODO: Functions supporting distinct should add a dedicated constructor Location, List<Expression>, boolean
     protected Function(Source source, List<Expression> children) {
         super(source, children);
@@ -65,17 +61,6 @@ public boolean equals(Object obj) {
         return Objects.equals(children(), other.children());
     }
 
-    public Pipe asPipe() {
-        if (lazyPipe == null) {
-            lazyPipe = foldable() ? new ConstantInput(source(), this, fold()) : makePipe();
-        }
-        return lazyPipe;
-    }
-
-    protected Pipe makePipe() {
-        throw new UnsupportedOperationException();
-    }
-
     @Override
     public String nodeString() {
         StringJoiner sj = new StringJoiner(",", functionName() + "(", ")");

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/expression/function/scalar/BaseSurrogateFunction.java

@@ -8,7 +8,6 @@
 package org.elasticsearch.xpack.esql.core.expression.function.scalar;
 
 import org.elasticsearch.xpack.esql.core.expression.Expression;
-import org.elasticsearch.xpack.esql.core.expression.gen.pipeline.Pipe;
 import org.elasticsearch.xpack.esql.core.tree.Source;
 
 import java.util.List;
@@ -45,8 +44,4 @@ public Object fold() {
         return substitute().fold();
     }
 
-    @Override
-    protected Pipe makePipe() {
-        return substitute().asPipe();
-    }
 }

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/expression/function/scalar/UnaryScalarFunction.java

@@ -7,9 +7,6 @@
 package org.elasticsearch.xpack.esql.core.expression.function.scalar;
 
 import org.elasticsearch.xpack.esql.core.expression.Expression;
-import org.elasticsearch.xpack.esql.core.expression.Expressions;
-import org.elasticsearch.xpack.esql.core.expression.gen.pipeline.Pipe;
-import org.elasticsearch.xpack.esql.core.expression.gen.pipeline.UnaryPipe;
 import org.elasticsearch.xpack.esql.core.expression.gen.processor.Processor;
 import org.elasticsearch.xpack.esql.core.tree.Source;
 
@@ -42,11 +39,6 @@ public Expression field() {
         return field;
     }
 
-    @Override
-    public final Pipe makePipe() {
-        return new UnaryPipe(source(), this, Expressions.pipe(field()), makeProcessor());
-    }
-
     protected abstract Processor makeProcessor();
 
     @Override