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https://issues.apache.org/jira/browse/TINKERPOP-1278?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15260825#comment-15260825
]
Marko A. Rodriguez commented on TINKERPOP-1278:
-----------------------------------------------
I decided to test the idea. Check it out:
Assume this is {{PythonVariantConverter}}.
{code}
public class VariantConverter {
public String source(final String source) {
return source;
}
public String concat() {
return ".";
}
public String step(final String stepName, final Object... args) {
if (args.length == 0)
return stepName + "()";
else
return stepName + "(" + stringify(args) + ")";
}
private static String stringify(final Object... args) {
String temp = "";
for (final Object object : args) {
if (object instanceof String) {
temp = temp + "\"${object}\",";
}
}
return temp.substring(0, temp.length() - 1);
}
}
{code}
{code}
class VariantTraversal implements GraphTraversal {
private static GremlinGroovyScriptEngine scriptEngine = new
GremlinGroovyScriptEngine();
private String variantString;
private String traversalSourceName;
private TraversalSource traversalSource;
private VariantConverter converter = new VariantConverter();
private Traversal traversal;
static {
VariantTraversal.metaClass.invokeMethod = { String name, args ->
if (name.equals("hasNext") || name.equals("next"))
return delegate.metaClass.getMetaMethod(name,
*args).invoke(delegate, args);
variantString = variantString + converter.concat() +
converter.step(name, args);
return delegate;
}
}
public VariantTraversal(final String traversalSourceName, final
TraversalSource traversalSource) {
this.traversalSourceName = traversalSourceName;
this.traversalSource = traversalSource;
this.variantString = traversalSourceName;
}
@Override
public String toString() {
return this.variantString;
}
@Override
boolean hasNext() {
if (null == this.traversal)
this.compile();
return this.traversal.hasNext();
}
@Override
Object next() {
if (null == this.traversal)
this.compile();
return this.traversal.next();
}
private void compile() {
SimpleBindings bindings = new SimpleBindings();
bindings.put(this.traversalSourceName, this.traversalSource);
this.traversal = (Traversal) scriptEngine.eval(this.variantString,
bindings);
}
}
{code}
{code}
class VariantTraversalTest {
@Test
public void playTest() {
final Graph graph = EmptyGraph.instance();
final Traversal traversal = new VariantTraversal("g",
graph.traversal()).V().out("created").groupCount().by("name");
println traversal;
println traversal.hasNext();
println traversal.next();
println traversal.hasNext();
}
}
{code}
The output of the test above is (note its an {{EmptyGraph}}):
{code}
g.V().out("created").groupCount().by("name")
true
[:]
false
{code}
There it is! ... All the language variant needs to do is implement their own
{{VariantConverter}}... Groovy and introspection and ScriptEngine, etc. will
take care of the rest.
> Support at least 3 Gremlin language variants.
> ---------------------------------------------
>
> Key: TINKERPOP-1278
> URL: https://issues.apache.org/jira/browse/TINKERPOP-1278
> Project: TinkerPop
> Issue Type: Improvement
> Affects Versions: 3.2.0-incubating
> Reporter: Marko A. Rodriguez
>
> As discussed on dev@...
> Apache TinkerPop should provide, out-of-the-box, at least 3 Gremlin language
> variants. It would be cool if these were:
> * Python (Mark Henderson)
> * PHP ([~PommeVerte])
> * Ruby (?[~okram])
> I think each of these should be generated using the reflection-model
> presented in
> http://tinkerpop.apache.org/docs/3.2.1-SNAPSHOT/tutorials/gremlin-language-variants/.
> Moreover, on every {{mvn clean install}}, the code for these variants is
> generated.
> Given the desire to separate language variants from language drivers, I think
> that a language driver for each variant above should be "plugable." Moreover,
> we should provide one driver implementation for each -- simple GremlinServer
> REST.
> {code}
> gremlin-variants/
> gremlin-ruby/
> gremlin_ruby.rb
> gremlin_ruby_rest_driver.rb
> gremlin-php/
> Gremlin_PHP.php
> Gremlin_PHP_REST_Driver.php
> gremlin-python/
> gremlin-python.py
> gremlin-python-rest-driver.py
> {code}
> Next, each variant implementation should be testable. This is PAINFUL if we
> have to implement each {{g_V_out_repeatXasXaXX}} test case in
> {{ProcessXXXSuite}}. Perhaps some RegEx transducer magic could be used to
> convert all those tests from Gremlin-Java to the respective host language?
> However, even if we do that, we still have the problem of how to test the
> returned results.
> I think what we should test the returned results using the JVM. For instance,
> JRuby, Jython, JPHP (does it exist?). If we do this, we will save ourselves a
> massive headache. All we have to do is create a {{GraphProvider}} that uses
> {{TinkerGraph}} and whose {{TraversalSource}} is some sort of wrapper around
> reflection-generated Ruby (e.g.).
> {code}
> g.V.out_e("knows") // returns a Ruby iterator
> {code}
> That Ruby iterator should be converted to a Java iterator and then the
> {{ProcessXXXSuite}} can verify the results.
> With this, most everything is reflectively constructed.
> {code}
> gremlin_ruby.rb // generated via Java reflection
> gremlin_ruby_rest_driver.rb // manually coded
> match_test.rb // generated via RegEx transducer
> has_test.rb // generated via RegEx transducer
> ...
> RubyGraphProvider.java // manually coded
> RubyProcessStandardSuite.java // manually coded
> RubyProcessComputerSuite.java // manually coded
> {code}
> Thus, the testing data flow would be:
> {code}
> MatchTest.Traversals.java --transducer-> match_test.rb
> match-test.rb --REST--> GremlinServer
> GremlinServer --GraphSON-->match-test.rb
> GraphSON --JRuby/GraphSONReader-->Java objects
> Java objects --JRuby-->MatchTest.java
> {code}
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