imbajin commented on code in PR #833:
URL:
https://github.com/apache/hugegraph-toolchain/pull/833#discussion_r4350417987
##########
hugegraph-hubble/hubble-be/src/main/java/org/apache/hugegraph/util/ReadOnlyGremlin.java:
##########
@@ -65,13 +143,183 @@ public static void validate(String query) {
if (!"V".equals(start) && !"E".equals(start)) {
throw invalid();
}
- parser.arguments(0);
- parser.chain(STEPS, 0);
+ List<Step> steps = new ArrayList<>();
+ steps.add(new Step(start, parser.arguments(0), 0));
+ parser.chain(STEPS.keySet(), 0, steps);
parser.consume(';');
parser.whitespace();
if (parser.position != query.length()) {
throw invalid();
}
+ return new Traversal(steps, query.length());
+ }
+
+ private enum Output {
+ PRESERVE, EXPAND, REDUCE, COLLECT, LIMIT, CONSUME
+ }
+
+ static final class Traversal {
+
+ private final List<Step> steps;
+ private final int endPosition;
+
+ private Traversal(List<Step> steps, int endPosition) {
+ this.steps = List.copyOf(steps);
+ this.endPosition = endPosition;
+ }
+
+ int limitPosition(boolean preview, int limit) {
+ // Preview limits include the sentinel row used to report
truncation.
+ BigInteger previewSize = BigInteger.valueOf((long) limit - 1);
+ Analysis result = this.analyze(previewSize);
+ if (preview && result.largeCollection) {
+ throw new
ExternalException("gremlin.preview.collection_requires_async", previewSize);
+ }
+ return !result.singleResult && (preview || result.bound == null) ?
result.position : -1;
+ }
+
+ private Analysis analyze(BigInteger previewSize) {
+ BigInteger bound = null;
+ boolean singleResult = false;
+ boolean largeCollection = false;
+ boolean nestedCollection = false;
+ int position = this.endPosition;
+ for (int i = 0; i < this.steps.size(); i++) {
+ Step step = this.steps.get(i);
+ switch (STEPS.get(step.name)) {
+ case CONSUME:
+ // Cap the traversal before its final consumer,
preserving
+ // the List/Set/value/boolean result type. Further
methods
+ // would operate on materialized results, outside this
grammar.
+ if (i != this.steps.size() - 1) {
+ return new Analysis(-1, bound, true, false);
+ }
+ position = step.dotPosition;
+ if ("hasNext".equals(step.name)) {
+ largeCollection = false;
+ nestedCollection = false;
+ }
+ break;
+ case EXPAND:
+ bound = null;
+ singleResult = false;
+ largeCollection = false;
+ break;
+ case REDUCE:
+ largeCollection = false;
+ nestedCollection = false;
+ if (!step.localScope()) {
+ bound = BigInteger.ONE;
+ singleResult = true;
+ }
+ break;
+ case COLLECT:
+ // The keyed group overloads accumulate a side effect
+ // while passing each input traverser through.
+ if (("group".equals(step.name) ||
"groupCount".equals(step.name)) &&
+ !step.arguments.isEmpty()) {
+ break;
+ }
+ if (!step.localScope()) {
+ // A single List/Map can still download an entire
+ // graph. A later outer limit cannot shrink its
input.
+ largeCollection |= bound == null ||
bound.compareTo(previewSize) > 0;
+ // group() values are collections; unfolding its
Map
+ // returns entries that retain those complete
values.
+ nestedCollection |= "group".equals(step.name) &&
largeCollection;
Review Comment:
The specific double-fold counterexample reported here is repaired at
7a6f3af6672d1c5f7ea4dae57820b117daad17c5. Independent bounded
parser/TinkerGraph checks confirmed rejection while preserving the checked safe
controls. Resolving this specific finding does not establish overall preview
completeness, current CI success, or full acceptance; the broader review
remains incomplete.
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