aai-core/src/main/java/org/onap/aai/query/builder/GraphTraversalBuilder.java

   1 /**
   2  * ============LICENSE_START=======================================================
   3  * org.onap.aai
   4  * ================================================================================
   5  * Copyright © 2017 AT&T Intellectual Property. All rights reserved.
   6  * ================================================================================
   7  * Licensed under the Apache License, Version 2.0 (the "License");
   8  * you may not use this file except in compliance with the License.
   9  * You may obtain a copy of the License at
  10  *
  11  *    http://www.apache.org/licenses/LICENSE-2.0
  12  *
  13  * Unless required by applicable law or agreed to in writing, software
  14  * distributed under the License is distributed on an "AS IS" BASIS,
  15  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  16  * See the License for the specific language governing permissions and
  17  * limitations under the License.
  18  * ============LICENSE_END=========================================================
  19  *
  20  * ECOMP is a trademark and service mark of AT&T Intellectual Property.
  21  */
  22 package org.onap.aai.query.builder;
  23
  24 import java.util.ArrayList;
  25 import java.util.List;
  26 import java.util.Map;
  27 import java.util.Optional;
  28 import java.util.Set;
  29
  30 import org.apache.tinkerpop.gremlin.process.traversal.P;
  31 import org.apache.tinkerpop.gremlin.process.traversal.Traversal;
  32 import org.apache.tinkerpop.gremlin.process.traversal.Traversal.Admin;
  33 import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal;
  34 import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversalSource;
  35 import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.__;
  36 import org.apache.tinkerpop.gremlin.process.traversal.util.TraversalHelper;
  37 import org.apache.tinkerpop.gremlin.structure.Direction;
  38 import org.apache.tinkerpop.gremlin.structure.Edge;
  39 import org.apache.tinkerpop.gremlin.structure.Vertex;
  40 import org.onap.aai.db.props.AAIProperties;
  41 import org.onap.aai.exceptions.AAIException;
  42 import org.onap.aai.introspection.Introspector;
  43 import org.onap.aai.introspection.Loader;
  44 import org.onap.aai.schema.enums.ObjectMetadata;
  45 import org.onap.aai.schema.enums.PropertyMetadata;
  46 import org.onap.aai.serialization.db.EdgeRule;
  47 import org.onap.aai.serialization.db.EdgeRules;
  48 import org.onap.aai.serialization.db.EdgeType;
  49 import org.onap.aai.serialization.db.exceptions.NoEdgeRuleFoundException;
  50
  51 /**
  52  * The Class GraphTraversalBuilder.
  53  */
  54 public abstract class GraphTraversalBuilder<E> extends QueryBuilder<E> {
  55
  56         protected GraphTraversal<Vertex, E> traversal = null;
  57         protected Admin<Vertex, E> completeTraversal = null;
  58         private EdgeRules edgeRules = EdgeRules.getInstance();
  59
  60         protected int parentStepIndex = 0;
  61         protected int containerStepIndex = 0;
  62         protected int stepIndex = 0;
  63
  64         /**
  65          * Instantiates a new graph traversal builder.
  66          *
  67          * @param loader the loader
  68          */
  69         public GraphTraversalBuilder(Loader loader, GraphTraversalSource source) {
  70                 super(loader, source);
  71
  72                 traversal = (GraphTraversal<Vertex, E>) __.<E>start();
  73
  74         }
  75
  76         /**
  77          * Instantiates a new graph traversal builder.
  78          *
  79          * @param loader the loader
  80          */
  81         public GraphTraversalBuilder(Loader loader, GraphTraversalSource source, EdgeRules edgeRules) {
  82                 super(loader, source);
  83                 this.edgeRules = edgeRules;
  84                 traversal = (GraphTraversal<Vertex, E>) __.<E>start();
  85
  86         }
  87
  88         /**
  89          * Instantiates a new graph traversal builder.
  90          *
  91          * @param loader the loader
  92          * @param start the start
  93          */
  94         public GraphTraversalBuilder(Loader loader, GraphTraversalSource source, Vertex start) {
  95                 super(loader, source, start);
  96
  97                 traversal = (GraphTraversal<Vertex, E>) __.__(start);
  98
  99         }
 100
 101         /**
 102          * Instantiates a new graph traversal builder.
 103          *
 104          * @param loader the loader
 105          * @param start the start
 106          */
 107         public GraphTraversalBuilder(Loader loader, GraphTraversalSource source, Vertex start, EdgeRules edgeRules) {
 108                 super(loader, source, start);
 109                 this.edgeRules = edgeRules;
 110                 traversal = (GraphTraversal<Vertex, E>) __.__(start);
 111
 112         }
 113
 114         /**
 115          * @{inheritDoc}
 116          */
 117         @Override
 118         public QueryBuilder<Vertex> getVerticesByProperty(String key, Object value) {
 119
 120                 // correct value call because the index is registered as an Integer
 121                 traversal.has(key, this.correctObjectType(value));
 122
 123                 stepIndex++;
 124                 return (QueryBuilder<Vertex>) this;
 125         }
 126
 127         /**
 128          * @{inheritDoc}
 129          */
 130         @Override
 131         public QueryBuilder<Vertex> getVerticesByProperty(final String key, final List<?> values) {
 132
 133                 //this is because the index is registered as an Integer
 134                 List<Object> correctedValues = new ArrayList<>();
 135                 for (Object item : values) {
 136                         correctedValues.add(this.correctObjectType(item));
 137                 }
 138
 139                 traversal.has(key, P.within(correctedValues));
 140
 141                 stepIndex++;
 142                 return (QueryBuilder<Vertex>) this;
 143         }
 144
 145         /**
 146          * @{inheritDoc}
 147          */
 148         @Override
 149         public QueryBuilder<Vertex> getVerticesExcludeByProperty(String key, Object value) {
 150
 151                 // correct value call because the index is registered as an Integer
 152                 traversal.has(key, P.neq(this.correctObjectType(value)));
 153
 154                 stepIndex++;
 155                 return (QueryBuilder<Vertex>) this;
 156         }
 157
 158         /**
 159          * @{inheritDoc}
 160          */
 161         @Override
 162         public QueryBuilder<Vertex> getVerticesExcludeByProperty(final String key, final List<?> values) {
 163
 164                 //this is because the index is registered as an Integer
 165                 List<Object> correctedValues = new ArrayList<>();
 166                 for (Object item : values) {
 167                         correctedValues.add(this.correctObjectType(item));
 168                 }
 169
 170                 traversal.has(key, P.without(correctedValues));
 171
 172                 stepIndex++;
 173                 return (QueryBuilder<Vertex>) this;
 174         }
 175
 176         /**
 177          * @{inheritDoc}
 178          */
 179         @Override
 180         public QueryBuilder<Vertex> getChildVerticesFromParent(String parentKey, String parentValue, String childType) {
 181                 traversal.has(parentKey, parentValue).has(AAIProperties.NODE_TYPE, childType);
 182                 stepIndex++;
 183                 return (QueryBuilder<Vertex>) this;
 184         }
 185
 186         /**
 187          * @{inheritDoc}
 188          */
 189         @Override
 190         public QueryBuilder<Vertex> getTypedVerticesByMap(String type, Map<String, String> map) {
 191
 192                 for (Map.Entry<String, String> es : map.entrySet()) {
 193                         traversal.has(es.getKey(), es.getValue());
 194                         stepIndex++;
 195                 }
 196                 traversal.has(AAIProperties.NODE_TYPE, type);
 197                 stepIndex++;
 198                 return (QueryBuilder<Vertex>) this;
 199         }
 200
 201         /**
 202          * @{inheritDoc}
 203          */
 204         @Override
 205         public QueryBuilder<Vertex> createKeyQuery(Introspector obj) {
 206                 Set<String> keys = obj.getKeys();
 207                 Object val;
 208                 for (String key : keys) {
 209                         val = obj.getValue(key);
 210                         Optional<String> metadata = obj.getPropertyMetadata(key, PropertyMetadata.DB_ALIAS);
 211                         if (metadata.isPresent()) {
 212                                 //use the db name for the field rather than the object model
 213                                 key = metadata.get();
 214                         }
 215                         if (val != null) {
 216                                 //this is because the index is registered as an Integer
 217                                 if (val.getClass().equals(Long.class)) {
 218                                         traversal.has(key,new Integer(val.toString()));
 219                                 } else {
 220                                         traversal.has(key, val);
 221                                 }
 222                                 stepIndex++;
 223                         }
 224                 }
 225                 return (QueryBuilder<Vertex>) this;
 226         }
 227
 228         @Override
 229         public QueryBuilder<Vertex> exactMatchQuery(Introspector obj) {
 230                 this.createKeyQuery(obj);
 231                 allPropertiesQuery(obj);
 232                 this.createContainerQuery(obj);
 233                 return (QueryBuilder<Vertex>) this;
 234         }
 235
 236         private void allPropertiesQuery(Introspector obj) {
 237                 Set<String> props = obj.getProperties();
 238                 Set<String> keys = obj.getKeys();
 239                 Object val;
 240                 for (String prop : props) {
 241                         if (obj.isSimpleType(prop) && !keys.contains(prop)) {
 242                                 val = obj.getValue(prop);
 243                                 if (val != null) {
 244                                         Optional<String> metadata = obj.getPropertyMetadata(prop, PropertyMetadata.DB_ALIAS);
 245                                         if (metadata.isPresent()) {
 246                                                 //use the db name for the field rather than the object model
 247                                                 prop = metadata.get();
 248                                         }
 249                                         //this is because the index is registered as an Integer
 250                                         if (val.getClass().equals(Long.class)) {
 251                                                 traversal.has(prop,new Integer(val.toString()));
 252                                         } else {
 253                                                 traversal.has(prop, val);
 254                                         }
 255                                         stepIndex++;
 256                                 }
 257                         }
 258                 }
 259         }
 260
 261         /**
 262          * @{inheritDoc}
 263          */
 264         @Override
 265
 266         public QueryBuilder<Vertex> createContainerQuery(Introspector obj) {
 267                 String type = obj.getChildDBName();
 268                 String abstractType = obj.getMetadata(ObjectMetadata.ABSTRACT);
 269                 if (abstractType != null) {
 270                         String[] inheritors = obj.getMetadata(ObjectMetadata.INHERITORS).split(",");
 271                         traversal.has(AAIProperties.NODE_TYPE, P.within(inheritors));
 272                 } else {
 273                         traversal.has(AAIProperties.NODE_TYPE, type);
 274                 }
 275                 stepIndex++;
 276                 markContainer();
 277                 return (QueryBuilder<Vertex>) this;
 278         }
 279
 280         /**
 281          * @throws NoEdgeRuleFoundException
 282          * @throws AAIException
 283          * @{inheritDoc}
 284          */
 285         @Override
 286         public QueryBuilder<Vertex> createEdgeTraversal(EdgeType type, Introspector parent, Introspector child) throws AAIException {
 287                 String isAbstractType = parent.getMetadata(ObjectMetadata.ABSTRACT);
 288                 if ("true".equals(isAbstractType)) {
 289                         markParentBoundary();
 290                         traversal.union(handleAbstractEdge(type, parent, child));
 291                         stepIndex++;
 292                 } else {
 293                         this.edgeQueryToVertex(type, parent, child, null);
 294                 }
 295                 return (QueryBuilder<Vertex>) this;
 296
 297         }
 298
 299         /**
 300          *
 301          * @{inheritDoc}
 302          */
 303         @Override
 304         public QueryBuilder<Vertex> createEdgeTraversalWithLabels(EdgeType type, Introspector out, Introspector in, List<String> labels) throws AAIException {
 305                 this.edgeQueryToVertex(type, out, in, labels);
 306                 return (QueryBuilder<Vertex>) this;
 307         }
 308
 309
 310         private Traversal<Vertex, Vertex>[] handleAbstractEdge(EdgeType type, Introspector abstractParent, Introspector child) throws AAIException, NoEdgeRuleFoundException {
 311                 String childName = child.getDbName();
 312                 String inheritorMetadata = abstractParent.getMetadata(ObjectMetadata.INHERITORS);
 313                 String[] inheritors = inheritorMetadata.split(",");
 314                 List<Traversal<Vertex, Vertex>> unionTraversals = new ArrayList<>(inheritors.length);
 315
 316                 for (int i = 0; i < inheritors.length; i++) {
 317                         String inheritor = inheritors[i];
 318                         if (edgeRules.hasEdgeRule(inheritor, childName) || edgeRules.hasEdgeRule(childName, inheritor)) {
 319                                 Map<String, EdgeRule> rules = edgeRules.getEdgeRules(type, inheritor, childName);
 320                                 GraphTraversal<Vertex, Vertex> innerTraversal = __.start();
 321
 322                                 final List<String> inLabels = new ArrayList<>();
 323                                 final List<String> outLabels = new ArrayList<>();
 324
 325                                 rules.forEach((k,v) -> {
 326                                         if (v.getDirection().equals(Direction.IN)) {
 327                                                 inLabels.add(k);
 328                                         } else {
 329                                                 outLabels.add(k);
 330                                         }
 331                                 } );
 332
 333                                 if (inLabels.isEmpty() && !outLabels.isEmpty()) {
 334                                         innerTraversal.out(outLabels.toArray(new String[outLabels.size()]));
 335                                 } else if (outLabels.isEmpty() && !inLabels.isEmpty()) {
 336                                         innerTraversal.in(inLabels.toArray(new String[inLabels.size()]));
 337                                 } else {
 338                                         innerTraversal.union(__.out(outLabels.toArray(new String[outLabels.size()])), __.in(inLabels.toArray(new String[inLabels.size()])));
 339                                 }
 340
 341                                 innerTraversal.has(AAIProperties.NODE_TYPE, childName);
 342                                 unionTraversals.add(innerTraversal);
 343                         }
 344                 }
 345
 346                 return unionTraversals.toArray(new Traversal[unionTraversals.size()]);
 347         }
 348
 349         public QueryBuilder<Edge> getEdgesBetweenWithLabels(EdgeType type, String outNodeType, String inNodeType, List<String> labels) throws AAIException {
 350                 Introspector outObj = loader.introspectorFromName(outNodeType);
 351                 Introspector inObj = loader.introspectorFromName(inNodeType);
 352                 this.edgeQuery(type, outObj, inObj, labels);
 353
 354                 return (QueryBuilder<Edge>)this;
 355         }
 356
 357
 358         /**
 359          * @{inheritDoc}
 360          */
 361         @Override
 362         public QueryBuilder<E> union(QueryBuilder... builder) {
 363                 GraphTraversal<Vertex, Vertex>[] traversals = new GraphTraversal[builder.length];
 364                 for (int i = 0; i < builder.length; i++) {
 365                         traversals[i] = (GraphTraversal<Vertex, Vertex>)builder[i].getQuery();
 366                 }
 367                 this.traversal.union(traversals);
 368                 stepIndex++;
 369
 370                 return this;
 371         }
 372
 373         /**
 374          * @{inheritDoc}
 375          */
 376         @Override
 377         public QueryBuilder<E> where(QueryBuilder... builder) {
 378                 GraphTraversal<Vertex, Vertex>[] traversals = new GraphTraversal[builder.length];
 379                 for (int i = 0; i < builder.length; i++) {
 380                         this.traversal.where((GraphTraversal<Vertex, Vertex>)builder[i].getQuery());
 381                         stepIndex++;
 382                 }
 383
 384                 return this;
 385         }
 386
 387         @Override
 388         public QueryBuilder<E> store(String name) {
 389
 390                 this.traversal.store(name);
 391                 stepIndex++;
 392
 393                 return this;
 394         }
 395
 396         @Override
 397         public QueryBuilder<E> cap(String name) {
 398                 this.traversal.cap(name);
 399                 stepIndex++;
 400
 401                 return this;
 402         }
 403
 404         @Override
 405         public QueryBuilder<E> unfold() {
 406                 this.traversal.unfold();
 407                 stepIndex++;
 408
 409                 return this;
 410         }
 411
 412         @Override
 413         public QueryBuilder<E> dedup() {
 414
 415                 this.traversal.dedup();
 416                 stepIndex++;
 417
 418                 return this;
 419         }
 420
 421         @Override
 422         public QueryBuilder<E> emit() {
 423
 424                 this.traversal.emit();
 425                 stepIndex++;
 426
 427                 return this;
 428
 429         }
 430
 431         @Override
 432         public QueryBuilder<E> repeat(QueryBuilder<E> builder) {
 433
 434                 this.traversal.repeat((GraphTraversal<Vertex, E>)builder.getQuery());
 435                 stepIndex++;
 436
 437                 return this;
 438         }
 439
 440         @Override
 441         public QueryBuilder<E> until(QueryBuilder<E> builder) {
 442                 this.traversal.until((GraphTraversal<Vertex,E>)builder.getQuery());
 443                 stepIndex++;
 444
 445                 return this;
 446         }
 447
 448         @Override
 449         public QueryBuilder<E> groupCount() {
 450                 this.traversal.groupCount();
 451                 stepIndex++;
 452
 453                 return this;
 454         }
 455
 456         @Override
 457         public QueryBuilder<E> both() {
 458                 this.traversal.both();
 459                 stepIndex++;
 460
 461                 return this;
 462         }
 463
 464         @Override
 465         public QueryBuilder<E> by(String name) {
 466                 this.traversal.by(name);
 467                 stepIndex++;
 468
 469                 return this;
 470         }
 471
 472         /**
 473          * {@inheritDoc}
 474          */
 475         @Override
 476         public QueryBuilder<E> simplePath(){
 477                 this.traversal.simplePath();
 478                 stepIndex++;
 479                 return this;
 480         }
 481
 482         @Override
 483         public QueryBuilder<Edge> outE() {
 484                 this.traversal.outE();
 485                 stepIndex++;
 486                 return (QueryBuilder<Edge>)this;
 487         }
 488
 489         @Override
 490         public QueryBuilder<Edge> inE() {
 491                 this.traversal.inE();
 492                 stepIndex++;
 493                 return (QueryBuilder<Edge>)this;
 494         }
 495
 496         @Override
 497         public QueryBuilder<Vertex> outV() {
 498                 this.traversal.outV();
 499                 stepIndex++;
 500                 return (QueryBuilder<Vertex>)this;
 501         }
 502
 503         @Override
 504         public QueryBuilder<Vertex> inV() {
 505                 this.traversal.inV();
 506                 stepIndex++;
 507                 return (QueryBuilder<Vertex>)this;
 508         }
 509
 510         @Override
 511         public QueryBuilder<E> as(String name) {
 512                 this.traversal.as(name);
 513
 514                 stepIndex++;
 515                 return this;
 516         }
 517
 518         @Override
 519         public QueryBuilder<E> not(QueryBuilder<E> builder) {
 520                 this.traversal.not(builder.getQuery());
 521
 522                 stepIndex++;
 523                 return this;
 524         }
 525
 526         @Override
 527         public QueryBuilder<E> select(String name) {
 528                 this.traversal.select(name);
 529
 530                 stepIndex++;
 531
 532                 return this;
 533         }
 534
 535         /**
 536          * Edge query.
 537          *
 538          * @param outObj the out type
 539          * @param inObj the in type
 540          * @throws NoEdgeRuleFoundException
 541          * @throws AAIException
 542          */
 543         private void edgeQueryToVertex(EdgeType type, Introspector outObj, Introspector inObj, List<String> labels) throws AAIException {
 544                 String outType = outObj.getDbName();
 545                 String inType = inObj.getDbName();
 546
 547                 if (outObj.isContainer()) {
 548                         outType = outObj.getChildDBName();
 549                 }
 550                 if (inObj.isContainer()) {
 551                         inType = inObj.getChildDBName();
 552                 }
 553                 markParentBoundary();
 554                 Map<String, EdgeRule> rules;
 555                 if (labels == null) {
 556                         rules = edgeRules.getEdgeRules(type, outType, inType);
 557                 } else {
 558                         rules = edgeRules.getEdgeRulesWithLabels(type, outType, inType, labels);
 559                 }
 560
 561                 final List<String> inLabels = new ArrayList<>();
 562                 final List<String> outLabels = new ArrayList<>();
 563
 564                 rules.forEach((k, edgeRule) -> {
 565                         if (labels != null && !labels.contains(k)) {
 566                                 return;
 567                         } else {
 568                                 if (edgeRule.getDirection().equals(Direction.IN)) {
 569                                         inLabels.add(edgeRule.getLabel());
 570                                 } else {
 571                                         outLabels.add(edgeRule.getLabel());
 572                                 }
 573                         }
 574                 });
 575
 576                 if (inLabels.isEmpty() && !outLabels.isEmpty()) {
 577                         traversal.out(outLabels.toArray(new String[outLabels.size()]));
 578                 } else if (outLabels.isEmpty() && !inLabels.isEmpty()) {
 579                         traversal.in(inLabels.toArray(new String[inLabels.size()]));
 580                 } else {
 581                         traversal.union(__.out(outLabels.toArray(new String[outLabels.size()])), __.in(inLabels.toArray(new String[inLabels.size()])));
 582                 }
 583
 584                 stepIndex++;
 585
 586                 this.createContainerQuery(inObj);
 587
 588         }
 589
 590         /**
 591          * Edge query.
 592          *
 593          * @param outObj the out type
 594          * @param inObj the in type
 595          * @throws NoEdgeRuleFoundException
 596          * @throws AAIException
 597          */
 598         private void edgeQuery(EdgeType type, Introspector outObj, Introspector inObj, List<String> labels) throws AAIException {
 599                 String outType = outObj.getDbName();
 600                 String inType = inObj.getDbName();
 601
 602                 if (outObj.isContainer()) {
 603                         outType = outObj.getChildDBName();
 604                 }
 605                 if (inObj.isContainer()) {
 606                         inType = inObj.getChildDBName();
 607                 }
 608
 609                 markParentBoundary();
 610                 Map<String, EdgeRule> rules;
 611                 if (labels == null) {
 612                         rules = edgeRules.getEdgeRules(type, outType, inType);
 613                 } else {
 614                         rules = edgeRules.getEdgeRulesWithLabels(type, outType, inType, labels);
 615                 }
 616
 617                 final List<String> inLabels = new ArrayList<>();
 618                 final List<String> outLabels = new ArrayList<>();
 619
 620                 rules.forEach((k, edgeRule) -> {
 621                         if (labels != null && !labels.contains(k)) {
 622                                 return;
 623                         } else {
 624                                 if (edgeRule.getDirection().equals(Direction.IN)) {
 625                                         inLabels.add(edgeRule.getLabel());
 626                                 } else {
 627                                         outLabels.add(edgeRule.getLabel());
 628                                 }
 629                         }
 630                 });
 631
 632                 if (inLabels.isEmpty() && !outLabels.isEmpty()) {
 633                         traversal.outE(outLabels.toArray(new String[outLabels.size()]));
 634                 } else if (outLabels.isEmpty() && !inLabels.isEmpty()) {
 635                         traversal.inE(inLabels.toArray(new String[inLabels.size()]));
 636                 } else {
 637                         traversal.union(__.outE(outLabels.toArray(new String[outLabels.size()])), __.inE(inLabels.toArray(new String[inLabels.size()])));
 638                 }
 639         }
 640
 641         @Override
 642         public QueryBuilder<E> limit(long amount) {
 643                 traversal.limit(amount);
 644                 return this;
 645         }
 646
 647         /**
 648          * @{inheritDoc}
 649          */
 650         @Override
 651         public <E2> E2 getQuery() {
 652                 return (E2)this.traversal;
 653         }
 654
 655         /**
 656          * @{inheritDoc}
 657          */
 658         @Override
 659         public QueryBuilder<E> getParentQuery() {
 660
 661                 return cloneQueryAtStep(parentStepIndex);
 662         }
 663
 664         @Override
 665         public QueryBuilder<E> getContainerQuery() {
 666
 667                 if (this.parentStepIndex == 0) {
 668                         return removeQueryStepsBetween(0, containerStepIndex);
 669                 } else {
 670                         return cloneQueryAtStep(containerStepIndex);
 671                 }
 672         }
 673
 674         /**
 675          * @{inheritDoc}
 676          */
 677         @Override
 678         public void markParentBoundary() {
 679                 parentStepIndex = stepIndex;
 680         }
 681
 682         @Override
 683         public void markContainer() {
 684                 containerStepIndex = stepIndex;
 685         }
 686
 687
 688         /**
 689          * @{inheritDoc}
 690          */
 691         @Override
 692         public Vertex getStart() {
 693                 return this.start;
 694         }
 695
 696         protected int getParentStepIndex() {
 697                 return parentStepIndex;
 698         }
 699
 700         protected int getContainerStepIndex() {
 701                 return containerStepIndex;
 702         }
 703
 704         protected int getStepIndex() {
 705                 return stepIndex;
 706         }
 707
 708         protected abstract QueryBuilder<E> cloneQueryAtStep(int index);
 709         /**
 710          * end is exclusive
 711          *
 712          * @param start
 713          * @param end
 714          * @return
 715          */
 716         protected abstract QueryBuilder<E> removeQueryStepsBetween(int start, int end);
 717
 718         private void executeQuery() {
 719
 720                 Admin admin;
 721                 if (start != null) {
 722                         this.completeTraversal = traversal.asAdmin();
 723                 } else {
 724                         admin = source.V().asAdmin();
 725                         TraversalHelper.insertTraversal(admin.getEndStep(), traversal.asAdmin(), admin);
 726
 727                         this.completeTraversal = (Admin<Vertex, E>) admin;
 728
 729                 }
 730
 731
 732         }
 733
 734         @Override
 735         public boolean hasNext() {
 736                 if (this.completeTraversal == null) {
 737                         executeQuery();
 738                 }
 739
 740                 return this.completeTraversal.hasNext();
 741         }
 742
 743         @Override
 744         public E next() {
 745                 if (this.completeTraversal == null) {
 746                         executeQuery();
 747                 }
 748
 749                 return this.completeTraversal.next();
 750         }
 751
 752         @Override
 753         public List<E> toList() {
 754                 if (this.completeTraversal == null) {
 755                         executeQuery();
 756                 }
 757
 758                 return this.completeTraversal.toList();
 759         }
 760
 761 }