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https://issues.apache.org/jira/browse/TINKERPOP-2959?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17901818#comment-17901818
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ASF GitHub Bot commented on TINKERPOP-2959:
-------------------------------------------
Cole-Greer commented on code in PR #2919:
URL: https://github.com/apache/tinkerpop/pull/2919#discussion_r1862781286
##########
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/GValue.java:
##########
@@ -0,0 +1,446 @@
+/*
+ * 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;
+
+import org.apache.tinkerpop.gremlin.process.traversal.Path;
+import org.apache.tinkerpop.gremlin.process.traversal.Traversal;
+import org.apache.tinkerpop.gremlin.structure.Edge;
+import org.apache.tinkerpop.gremlin.structure.Element;
+import org.apache.tinkerpop.gremlin.structure.Property;
+import org.apache.tinkerpop.gremlin.structure.Vertex;
+
+import java.io.Serializable;
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+import java.util.stream.Stream;
+
+/**
+ * A {@code GValue} is a variable or literal value that is used in a {@link
Traversal}. It is composed of a key-value
+ * pair where the key is the name given to the variable and the value is the
object that the variable resolved to. If
+ * the name is not given, the value was provided literally in the traversal.
The value of the variable can be any
+ * object. The {@code GValue} also includes the {@link GType} that describes
the type it contains.
+ */
+public class GValue<V> implements Cloneable, Serializable {
+ private final String name;
+ private final GType type;
+
+ private final V value;
+
+ private GValue(final GType type, final V value) {
+ this(null, type, value);
+ }
+
+ private GValue(final String name, final GType type, final V value) {
+ if (name != null && name.startsWith("_")) {
+ throw new IllegalArgumentException(String.format("Invalid GValue
name [%s]. Should not start with _.", name));
+ }
+ this.name = name;
+ this.type = type;
+ this.value = value;
+ }
+
+ /**
+ * Determines if the value held by this object was defined as a variable
or a literal value. Literal values simply
+ * have no name.
+ */
+ public boolean isVariable() {
+ return this.name != null;
+ }
+
+ /**
+ * Gets the name of the variable if it was defined as such and returns
empty if the value was a literal.
+ */
+ public String getName() {
+ return this.name;
+ }
+
+ /**
+ * Gets the type of the value. The explicit type could be determined with
{@code instanceof} on the value, but this
+ * might be helpful for cases where the value was constructed with a
{@code null} value which might just return as
+ * {@code Object}.
+ */
+ public GType getType() {
+ return this.type;
+ }
+
+ /**
+ * Determines if the value held is of a {@code null} value.
+ */
+ public boolean isNull() {
+ return this.value == null;
+ }
+
+ /**
+ * Gets the value.
+ */
+ public V get() {
+ return this.value;
+ }
+
+ @Override
+ public String toString() {
+ return isVariable() ?
+ String.format("%s&%s", name, value) : Objects.toString(value);
+ }
+
+ @Override
+ public boolean equals(final Object o) {
+ if (this == o) return true;
+ if (o == null || getClass() != o.getClass()) return false;
+ final GValue<?> gValue = (GValue<?>) o;
+ return Objects.equals(name, gValue.name) && type == gValue.type &&
Objects.equals(value, gValue.value);
+ }
+
+ @Override
+ public int hashCode() {
+ return Objects.hash(name, type, value);
+ }
+
+ /**
+ * Create a new {@code Var} from a particular value but without the
specified name. If the argument provide is
+ * already a {@code GValue} then it is returned as-is.
+ *
+ * @param value the value of the variable
+ */
+ static <V> GValue<V> of(final V value) {
+ if (value instanceof GValue) return (GValue) value;
+ return new GValue<>(GType.getType(value), value);
+ }
+
+ /**
+ * Create a new {@code Var} with the specified name and value.. If the
argument provide is already a
+ * {@code GValue} then it is returned as-is.
+ *
+ * @param name the name of the variable
+ * @param value the value of the variable
+ */
+ public static <V> GValue<V> of(final String name, final V value) {
+ if (value instanceof GValue) throw new IllegalArgumentException("value
cannot be a GValue");
Review Comment:
Returning a `GValue` as is may not be desirable for this method as the users
intentions are unclear in any case where the newly provided name does not match
the existing name in the GValue. I have updated the javadoc accordingly but
kept the implemented behavior.
> Allow the grammar to support parameters
> ---------------------------------------
>
> Key: TINKERPOP-2959
> URL: https://issues.apache.org/jira/browse/TINKERPOP-2959
> Project: TinkerPop
> Issue Type: Improvement
> Components: language
> Affects Versions: 3.6.4
> Reporter: Stephen Mallette
> Assignee: Stephen Mallette
> Priority: Major
> Fix For: 3.7.0
>
>
> Allow the grammar to support parameters similar to how the groovy engine does
> like, {{g.inject(x,y,z)}}. Doing this will make it easier for a transition
> away from the groovy engine as a lot of Gremlin in the world today uses
> parameters. The grammar may have to come with some limitations though as
> groovy is wide open in terms of what can be treated as a variable. Probably
> going to keep parameters tied to primitives, collections and tokens/enums
> like {{Order}} and {{Scope}}. Collections themselves will not contain
> parameters and things like a {{Traversal}} or {{P}} cannot be treated as one.
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