Cole-Greer commented on code in PR #3458:
URL: https://github.com/apache/tinkerpop/pull/3458#discussion_r3437661737
##########
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/P.java:
##########
@@ -453,6 +697,106 @@ public static <V> P<V> without(final Collection<V> value)
{
return new P(Contains.without, value);
}
+ /**
+ * Determines if values are equal using a child traversal resolved at
runtime.
+ *
+ * @since 4.0.0
+ */
+ public static <V> P<V> eq(final Traversal<?, ?> traversalValue) {
+ ChildTraversalValidator.validate(traversalValue.asAdmin());
+ return new P(Compare.eq, traversalValue.asAdmin());
+ }
+
+ /**
+ * Determines if values are not equal using a child traversal resolved at
runtime.
+ *
+ * @since 4.0.0
+ */
+ public static <V> P<V> neq(final Traversal<?, ?> traversalValue) {
+ ChildTraversalValidator.validate(traversalValue.asAdmin());
+ return new P(Compare.neq, traversalValue.asAdmin());
+ }
+
+ /**
+ * Determines if a value is less than another using a child traversal
resolved at runtime.
+ *
+ * @since 4.0.0
+ */
+ public static <V> P<V> lt(final Traversal<?, ?> traversalValue) {
+ ChildTraversalValidator.validate(traversalValue.asAdmin());
+ return new P(Compare.lt, traversalValue.asAdmin());
+ }
+
+ /**
+ * Determines if a value is less than or equal to another using a child
traversal resolved at runtime.
+ *
+ * @since 4.0.0
+ */
+ public static <V> P<V> lte(final Traversal<?, ?> traversalValue) {
+ ChildTraversalValidator.validate(traversalValue.asAdmin());
+ return new P(Compare.lte, traversalValue.asAdmin());
+ }
+
+ /**
+ * Determines if a value is greater than another using a child traversal
resolved at runtime.
+ *
+ * @since 4.0.0
+ */
+ public static <V> P<V> gt(final Traversal<?, ?> traversalValue) {
+ ChildTraversalValidator.validate(traversalValue.asAdmin());
+ return new P(Compare.gt, traversalValue.asAdmin());
+ }
+
+ /**
+ * Determines if a value is greater than or equal to another using a child
traversal resolved at runtime.
+ *
+ * @since 4.0.0
+ */
+ public static <V> P<V> gte(final Traversal<?, ?> traversalValue) {
+ ChildTraversalValidator.validate(traversalValue.asAdmin());
+ return new P(Compare.gte, traversalValue.asAdmin());
+ }
+
+ /**
+ * Determines if a value is within the results of a child traversal
resolved at runtime.
+ *
+ * @since 4.0.0
+ */
+ public static <V> P<V> within(final Traversal<?, ?> traversalValue) {
+ ChildTraversalValidator.validate(traversalValue.asAdmin());
+ return new P(Contains.within, traversalValue.asAdmin());
+ }
+
+ /**
+ * Determines if a value is within the union of results from multiple
child traversals resolved at runtime.
+ * Each traversal is evaluated independently and results are combined into
a single collection.
+ *
+ * @since 4.0.0
+ */
+ public static <V> P<V> within(final Traversal<?, ?> first, final
Traversal<?, ?> second, final Traversal<?, ?>... more) {
+ return containsTraversals(Contains.within, first, second, more);
+ }
+
+ /**
+ * Determines if a value is not within the results of a child traversal
resolved at runtime.
+ *
+ * @since 4.0.0
+ */
+ public static <V> P<V> without(final Traversal<?, ?> traversalValue) {
+ ChildTraversalValidator.validate(traversalValue.asAdmin());
+ return new P(Contains.without, traversalValue.asAdmin());
+ }
+
+ /**
+ * Determines if a value is not within the union of results from multiple
child traversals resolved at runtime.
+ * Each traversal is evaluated independently and results are combined into
a single collection.
+ *
+ * @since 4.0.0
+ */
+ public static <V> P<V> without(final Traversal<?, ?> first, final
Traversal<?, ?> second, final Traversal<?, ?>... more) {
Review Comment:
a minimum of a `first, more...` overload is necessary to disambiguate the
zero arg calls to these methods.
##########
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/P.java:
##########
@@ -49,10 +56,23 @@ public class P<V> implements Predicate<V>, Serializable,
Cloneable {
protected Map<String, V> variables = new HashMap<>();
protected Collection<V> literals = Collections.EMPTY_LIST;
private boolean isCollection = false;
+ private boolean resolvedEmpty = false;
+ private Traversal.Admin<?, ?> traversalValue;
+ private List<Traversal.Admin<?, ?>> traversalValues;
Review Comment:
I experimented with this a bit, and it really just moving problems around
instead of solving them. The real issue is the pre-existing extent to which the
generics are abused in P. I think a larger P refactor would be beneficial at
some point, but definitely beyond the scope of this work.
##########
docs/src/upgrade/release-4.x.x.asciidoc:
##########
@@ -101,6 +70,51 @@ partial work is discarded if the user forgets to call
`commit()`. In Java (both
can still be overridden via `tx.onClose(Transaction.CLOSE_BEHAVIOR.COMMIT)`.
The non-Java GLVs do not support
configuring close behavior and always rollback.
+==== Expanding Dynamic Arguments to Additional Steps
+
+Prior to 4.0, comparing a traverser's value against a dynamically computed
reference required verbose workarounds with
+`where()`, `select()`, and labeled steps. For example, finding all people
older than "marko" previously required:
+
+[source,groovy]
Review Comment:
The upgrade docs examples should remain static such that they remain as-is
following future releases. I don't think the results are particularly
interesting for these traversals, however I can add static emulated console
output.
##########
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/AcceptsChildPredicateTraversal.java:
##########
@@ -0,0 +1,34 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.tinkerpop.gremlin.process.traversal.step;
+
+/**
+ * Marker interface for steps that accept user-supplied child traversals
embedded as predicate or lookup
Review Comment:
I think this points to a larger branding/framing problem with this
interface. I've renamed it `ReadOnlyTraversalParent` and updated the javadoc.
See below thread for more details.
##########
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/AcceptsChildPredicateTraversal.java:
##########
@@ -0,0 +1,34 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.tinkerpop.gremlin.process.traversal.step;
+
+/**
+ * Marker interface for steps that accept user-supplied child traversals
embedded as predicate or lookup
+ * arguments (for example {@code has(key, traversal)}, {@code
is(P.gt(traversal))},
+ * {@code V(traversal)}, or {@code property(traversal)}).
+ * <p>
+ * The {@link
org.apache.tinkerpop.gremlin.process.traversal.strategy.verification.ChildTraversalVerificationStrategy}
+ * validates the local children of every step implementing this interface,
rejecting child traversals that
+ * contain mutating steps. New steps that accept such traversals should
implement this interface so they are
+ * validated automatically rather than relying on a hardcoded step list.
+ *
+ * @since 4.0.0
+ */
+public interface AcceptsChildPredicateTraversal {
Review Comment:
I've opted to go in a different direction on this one, renaming it to
`ReadOnlyTraversalParent extends TraversalParent`. I added the `extends
TraversalParent` as I don't think this marker interface makes any sense for
steps which are not already TraversalParents. I also think that this new
framing is easier to understand, it is a `TraversalParent` with a `ReadOnly`
restriction applied.
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