Source code

001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2024 the original author or authors.
004//
005// This library is free software; you can redistribute it and/or
006// modify it under the terms of the GNU Lesser General Public
007// License as published by the Free Software Foundation; either
008// version 2.1 of the License, or (at your option) any later version.
009//
010// This library is distributed in the hope that it will be useful,
011// but WITHOUT ANY WARRANTY; without even the implied warranty of
012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
013// Lesser General Public License for more details.
014//
015// You should have received a copy of the GNU Lesser General Public
016// License along with this library; if not, write to the Free Software
017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
018///////////////////////////////////////////////////////////////////////////////////////////////
019
020package com.puppycrawl.tools.checkstyle;
021
022import java.util.ArrayList;
023import java.util.Collections;
024import java.util.Iterator;
025import java.util.List;
026import java.util.Optional;
027import java.util.Queue;
028import java.util.concurrent.ConcurrentLinkedQueue;
029import java.util.stream.Collectors;
030
031import org.antlr.v4.runtime.BufferedTokenStream;
032import org.antlr.v4.runtime.CommonTokenStream;
033import org.antlr.v4.runtime.ParserRuleContext;
034import org.antlr.v4.runtime.Token;
035import org.antlr.v4.runtime.tree.ParseTree;
036import org.antlr.v4.runtime.tree.TerminalNode;
037
038import com.puppycrawl.tools.checkstyle.api.TokenTypes;
039import com.puppycrawl.tools.checkstyle.grammar.java.JavaLanguageLexer;
040import com.puppycrawl.tools.checkstyle.grammar.java.JavaLanguageParser;
041import com.puppycrawl.tools.checkstyle.grammar.java.JavaLanguageParserBaseVisitor;
042import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
043
044/**
045 * Visitor class used to build Checkstyle's Java AST from the parse tree produced by
046 * {@link JavaLanguageParser}. In each {@code visit...} method, we visit the children of a node
047 * (which correspond to subrules) or create terminal nodes (tokens), and return a subtree as a
048 * result.
049 *
050 * <p>Example:</p>
051 *
052 * <p>The following package declaration:</p>
053 * <pre>
054 * package com.puppycrawl.tools.checkstyle;
055 * </pre>
056 *
057 * <p>
058 * Will be parsed by the {@code packageDeclaration} rule from {@code JavaLanguageParser.g4}:
059 * </p>
060 * <pre>
061 * packageDeclaration
062 *     : annotations[true] LITERAL_PACKAGE qualifiedName SEMI
063 *     ;
064 * </pre>
065 *
066 * <p>
067 * We override the {@code visitPackageDeclaration} method generated by ANTLR in
068 * {@link JavaLanguageParser} at
069 * {@link JavaAstVisitor#visitPackageDeclaration(JavaLanguageParser.PackageDeclarationContext)}
070 * to create a subtree based on the subrules and tokens found in the {@code packageDeclaration}
071 * subrule accordingly, thus producing the following AST:
072 * </p>
073 * <pre>
074 * PACKAGE_DEF -&gt; package
075 * |--ANNOTATIONS -&gt; ANNOTATIONS
076 * |--DOT -&gt; .
077 * |   |--DOT -&gt; .
078 * |   |   |--DOT -&gt; .
079 * |   |   |   |--IDENT -&gt; com
080 * |   |   |   `--IDENT -&gt; puppycrawl
081 * |   |   `--IDENT -&gt; tools
082 * |   `--IDENT -&gt; checkstyle
083 * `--SEMI -&gt; ;
084 * </pre>
085 *
086 * <p>
087 * See <a href="https://github.com/checkstyle/checkstyle/pull/10434">#10434</a>
088 * for a good example of how
089 * to make changes to Checkstyle's grammar and AST.
090 * </p>
091 *
092 * <p>
093 * The order of {@code visit...} methods in {@code JavaAstVisitor.java} and production rules in
094 * {@code JavaLanguageParser.g4} should be consistent to ease maintenance.
095 * </p>
096 */
097public final class JavaAstVisitor extends JavaLanguageParserBaseVisitor<DetailAstImpl> {
098
099    /** String representation of the left shift operator. */
100    private static final String LEFT_SHIFT = "<<";
101
102    /** String representation of the unsigned right shift operator. */
103    private static final String UNSIGNED_RIGHT_SHIFT = ">>>";
104
105    /** String representation of the right shift operator. */
106    private static final String RIGHT_SHIFT = ">>";
107
108    /**
109     * The tokens here are technically expressions, but should
110     * not return an EXPR token as their root.
111     */
112    private static final int[] EXPRESSIONS_WITH_NO_EXPR_ROOT = {
113        TokenTypes.CTOR_CALL,
114        TokenTypes.SUPER_CTOR_CALL,
115        TokenTypes.LAMBDA,
116    };
117
118    /** Token stream to check for hidden tokens. */
119    private final BufferedTokenStream tokens;
120
121    /**
122     * Constructs a JavaAstVisitor with given token stream.
123     *
124     * @param tokenStream the token stream to check for hidden tokens
125     */
126    public JavaAstVisitor(CommonTokenStream tokenStream) {
127        tokens = tokenStream;
128    }
129
130    @Override
131    public DetailAstImpl visitCompilationUnit(JavaLanguageParser.CompilationUnitContext ctx) {
132        final DetailAstImpl compilationUnit;
133        // 'EOF' token is always present; therefore if we only have one child, we have an empty file
134        final boolean isEmptyFile = ctx.children.size() == 1;
135        if (isEmptyFile) {
136            compilationUnit = null;
137        }
138        else {
139            compilationUnit = createImaginary(TokenTypes.COMPILATION_UNIT);
140            // last child is 'EOF', we do not include this token in AST
141            processChildren(compilationUnit, ctx.children.subList(0, ctx.children.size() - 1));
142        }
143        return compilationUnit;
144    }
145
146    @Override
147    public DetailAstImpl visitPackageDeclaration(
148            JavaLanguageParser.PackageDeclarationContext ctx) {
149        final DetailAstImpl packageDeclaration =
150                create(TokenTypes.PACKAGE_DEF, (Token) ctx.LITERAL_PACKAGE().getPayload());
151        packageDeclaration.addChild(visit(ctx.annotations()));
152        packageDeclaration.addChild(visit(ctx.qualifiedName()));
153        packageDeclaration.addChild(create(ctx.SEMI()));
154        return packageDeclaration;
155    }
156
157    @Override
158    public DetailAstImpl visitImportDec(JavaLanguageParser.ImportDecContext ctx) {
159        final DetailAstImpl importRoot = create(ctx.start);
160
161        // Static import
162        final TerminalNode literalStaticNode = ctx.LITERAL_STATIC();
163        if (literalStaticNode != null) {
164            importRoot.setType(TokenTypes.STATIC_IMPORT);
165            importRoot.addChild(create(literalStaticNode));
166        }
167
168        // Handle star imports
169        final boolean isStarImport = ctx.STAR() != null;
170        if (isStarImport) {
171            final DetailAstImpl dot = create(ctx.DOT());
172            dot.addChild(visit(ctx.qualifiedName()));
173            dot.addChild(create(ctx.STAR()));
174            importRoot.addChild(dot);
175        }
176        else {
177            importRoot.addChild(visit(ctx.qualifiedName()));
178        }
179
180        importRoot.addChild(create(ctx.SEMI()));
181        return importRoot;
182    }
183
184    @Override
185    public DetailAstImpl visitSingleSemiImport(JavaLanguageParser.SingleSemiImportContext ctx) {
186        return create(ctx.SEMI());
187    }
188
189    @Override
190    public DetailAstImpl visitTypeDeclaration(JavaLanguageParser.TypeDeclarationContext ctx) {
191        final DetailAstImpl typeDeclaration;
192        if (ctx.type == null) {
193            typeDeclaration = create(ctx.semi.get(0));
194            ctx.semi.subList(1, ctx.semi.size())
195                    .forEach(semi -> addLastSibling(typeDeclaration, create(semi)));
196        }
197        else {
198            typeDeclaration = visit(ctx.type);
199        }
200        return typeDeclaration;
201    }
202
203    @Override
204    public DetailAstImpl visitModifier(JavaLanguageParser.ModifierContext ctx) {
205        return flattenedTree(ctx);
206    }
207
208    @Override
209    public DetailAstImpl visitVariableModifier(JavaLanguageParser.VariableModifierContext ctx) {
210        return flattenedTree(ctx);
211    }
212
213    @Override
214    public DetailAstImpl visitClassDeclaration(JavaLanguageParser.ClassDeclarationContext ctx) {
215        return createTypeDeclaration(ctx, TokenTypes.CLASS_DEF, ctx.mods);
216    }
217
218    @Override
219    public DetailAstImpl visitRecordDeclaration(JavaLanguageParser.RecordDeclarationContext ctx) {
220        return createTypeDeclaration(ctx, TokenTypes.RECORD_DEF, ctx.mods);
221    }
222
223    @Override
224    public DetailAstImpl visitRecordComponentsList(
225            JavaLanguageParser.RecordComponentsListContext ctx) {
226        final DetailAstImpl lparen = create(ctx.LPAREN());
227
228        // We make a "RECORD_COMPONENTS" node whether components exist or not
229        if (ctx.recordComponents() == null) {
230            addLastSibling(lparen, createImaginary(TokenTypes.RECORD_COMPONENTS));
231        }
232        else {
233            addLastSibling(lparen, visit(ctx.recordComponents()));
234        }
235        addLastSibling(lparen, create(ctx.RPAREN()));
236        return lparen;
237    }
238
239    @Override
240    public DetailAstImpl visitRecordComponents(JavaLanguageParser.RecordComponentsContext ctx) {
241        final DetailAstImpl recordComponents = createImaginary(TokenTypes.RECORD_COMPONENTS);
242        processChildren(recordComponents, ctx.children);
243        return recordComponents;
244    }
245
246    @Override
247    public DetailAstImpl visitRecordComponent(JavaLanguageParser.RecordComponentContext ctx) {
248        final DetailAstImpl recordComponent = createImaginary(TokenTypes.RECORD_COMPONENT_DEF);
249        processChildren(recordComponent, ctx.children);
250        return recordComponent;
251    }
252
253    @Override
254    public DetailAstImpl visitLastRecordComponent(
255            JavaLanguageParser.LastRecordComponentContext ctx) {
256        final DetailAstImpl recordComponent = createImaginary(TokenTypes.RECORD_COMPONENT_DEF);
257        processChildren(recordComponent, ctx.children);
258        return recordComponent;
259    }
260
261    @Override
262    public DetailAstImpl visitRecordBody(JavaLanguageParser.RecordBodyContext ctx) {
263        final DetailAstImpl objBlock = createImaginary(TokenTypes.OBJBLOCK);
264        processChildren(objBlock, ctx.children);
265        return objBlock;
266    }
267
268    @Override
269    public DetailAstImpl visitCompactConstructorDeclaration(
270            JavaLanguageParser.CompactConstructorDeclarationContext ctx) {
271        final DetailAstImpl compactConstructor = createImaginary(TokenTypes.COMPACT_CTOR_DEF);
272        compactConstructor.addChild(createModifiers(ctx.mods));
273        compactConstructor.addChild(visit(ctx.id()));
274        compactConstructor.addChild(visit(ctx.constructorBlock()));
275        return compactConstructor;
276    }
277
278    @Override
279    public DetailAstImpl visitClassExtends(JavaLanguageParser.ClassExtendsContext ctx) {
280        final DetailAstImpl classExtends = create(ctx.EXTENDS_CLAUSE());
281        classExtends.addChild(visit(ctx.type));
282        return classExtends;
283    }
284
285    @Override
286    public DetailAstImpl visitImplementsClause(JavaLanguageParser.ImplementsClauseContext ctx) {
287        final DetailAstImpl classImplements = create(TokenTypes.IMPLEMENTS_CLAUSE,
288                (Token) ctx.LITERAL_IMPLEMENTS().getPayload());
289        classImplements.addChild(visit(ctx.typeList()));
290        return classImplements;
291    }
292
293    @Override
294    public DetailAstImpl visitTypeParameters(JavaLanguageParser.TypeParametersContext ctx) {
295        final DetailAstImpl typeParameters = createImaginary(TokenTypes.TYPE_PARAMETERS);
296        typeParameters.addChild(create(TokenTypes.GENERIC_START, (Token) ctx.LT().getPayload()));
297        // Exclude '<' and '>'
298        processChildren(typeParameters, ctx.children.subList(1, ctx.children.size() - 1));
299        typeParameters.addChild(create(TokenTypes.GENERIC_END, (Token) ctx.GT().getPayload()));
300        return typeParameters;
301    }
302
303    @Override
304    public DetailAstImpl visitTypeParameter(JavaLanguageParser.TypeParameterContext ctx) {
305        final DetailAstImpl typeParameter = createImaginary(TokenTypes.TYPE_PARAMETER);
306        processChildren(typeParameter, ctx.children);
307        return typeParameter;
308    }
309
310    @Override
311    public DetailAstImpl visitTypeUpperBounds(JavaLanguageParser.TypeUpperBoundsContext ctx) {
312        // In this case, we call 'extends` TYPE_UPPER_BOUNDS
313        final DetailAstImpl typeUpperBounds = create(TokenTypes.TYPE_UPPER_BOUNDS,
314                (Token) ctx.EXTENDS_CLAUSE().getPayload());
315        // 'extends' is child[0]
316        processChildren(typeUpperBounds, ctx.children.subList(1, ctx.children.size()));
317        return typeUpperBounds;
318    }
319
320    @Override
321    public DetailAstImpl visitTypeBound(JavaLanguageParser.TypeBoundContext ctx) {
322        final DetailAstImpl typeBoundType = visit(ctx.typeBoundType(0));
323        final Iterator<JavaLanguageParser.TypeBoundTypeContext> typeBoundTypeIterator =
324                ctx.typeBoundType().listIterator(1);
325        ctx.BAND().forEach(band -> {
326            addLastSibling(typeBoundType, create(TokenTypes.TYPE_EXTENSION_AND,
327                                (Token) band.getPayload()));
328            addLastSibling(typeBoundType, visit(typeBoundTypeIterator.next()));
329        });
330        return typeBoundType;
331    }
332
333    @Override
334    public DetailAstImpl visitTypeBoundType(JavaLanguageParser.TypeBoundTypeContext ctx) {
335        return flattenedTree(ctx);
336    }
337
338    @Override
339    public DetailAstImpl visitEnumDeclaration(JavaLanguageParser.EnumDeclarationContext ctx) {
340        return createTypeDeclaration(ctx, TokenTypes.ENUM_DEF, ctx.mods);
341    }
342
343    @Override
344    public DetailAstImpl visitEnumBody(JavaLanguageParser.EnumBodyContext ctx) {
345        final DetailAstImpl objBlock = createImaginary(TokenTypes.OBJBLOCK);
346        processChildren(objBlock, ctx.children);
347        return objBlock;
348    }
349
350    @Override
351    public DetailAstImpl visitEnumConstants(JavaLanguageParser.EnumConstantsContext ctx) {
352        return flattenedTree(ctx);
353    }
354
355    @Override
356    public DetailAstImpl visitEnumConstant(JavaLanguageParser.EnumConstantContext ctx) {
357        final DetailAstImpl enumConstant =
358                createImaginary(TokenTypes.ENUM_CONSTANT_DEF);
359        processChildren(enumConstant, ctx.children);
360        return enumConstant;
361    }
362
363    @Override
364    public DetailAstImpl visitEnumBodyDeclarations(
365            JavaLanguageParser.EnumBodyDeclarationsContext ctx) {
366        return flattenedTree(ctx);
367    }
368
369    @Override
370    public DetailAstImpl visitInterfaceDeclaration(
371            JavaLanguageParser.InterfaceDeclarationContext ctx) {
372        return createTypeDeclaration(ctx, TokenTypes.INTERFACE_DEF, ctx.mods);
373    }
374
375    @Override
376    public DetailAstImpl visitInterfaceExtends(JavaLanguageParser.InterfaceExtendsContext ctx) {
377        final DetailAstImpl interfaceExtends = create(ctx.EXTENDS_CLAUSE());
378        interfaceExtends.addChild(visit(ctx.typeList()));
379        return interfaceExtends;
380    }
381
382    @Override
383    public DetailAstImpl visitClassBody(JavaLanguageParser.ClassBodyContext ctx) {
384        final DetailAstImpl objBlock = createImaginary(TokenTypes.OBJBLOCK);
385        processChildren(objBlock, ctx.children);
386        return objBlock;
387    }
388
389    @Override
390    public DetailAstImpl visitInterfaceBody(JavaLanguageParser.InterfaceBodyContext ctx) {
391        final DetailAstImpl objBlock = createImaginary(TokenTypes.OBJBLOCK);
392        processChildren(objBlock, ctx.children);
393        return objBlock;
394    }
395
396    @Override
397    public DetailAstImpl visitEmptyClass(JavaLanguageParser.EmptyClassContext ctx) {
398        return flattenedTree(ctx);
399    }
400
401    @Override
402    public DetailAstImpl visitClassBlock(JavaLanguageParser.ClassBlockContext ctx) {
403        final DetailAstImpl classBlock;
404        if (ctx.LITERAL_STATIC() == null) {
405            // We call it an INSTANCE_INIT
406            classBlock = createImaginary(TokenTypes.INSTANCE_INIT);
407        }
408        else {
409            classBlock = create(TokenTypes.STATIC_INIT, (Token) ctx.LITERAL_STATIC().getPayload());
410            classBlock.setText(TokenUtil.getTokenName(TokenTypes.STATIC_INIT));
411        }
412        classBlock.addChild(visit(ctx.block()));
413        return classBlock;
414    }
415
416    @Override
417    public DetailAstImpl visitMethodDeclaration(JavaLanguageParser.MethodDeclarationContext ctx) {
418        final DetailAstImpl methodDef = createImaginary(TokenTypes.METHOD_DEF);
419        methodDef.addChild(createModifiers(ctx.mods));
420
421        // Process all children except C style array declarators
422        processChildren(methodDef, ctx.children.stream()
423                .filter(child -> !(child instanceof JavaLanguageParser.ArrayDeclaratorContext))
424                .collect(Collectors.toUnmodifiableList()));
425
426        // We add C style array declarator brackets to TYPE ast
427        final DetailAstImpl typeAst = (DetailAstImpl) methodDef.findFirstToken(TokenTypes.TYPE);
428        ctx.cStyleArrDec.forEach(child -> typeAst.addChild(visit(child)));
429
430        return methodDef;
431    }
432
433    @Override
434    public DetailAstImpl visitMethodBody(JavaLanguageParser.MethodBodyContext ctx) {
435        return flattenedTree(ctx);
436    }
437
438    @Override
439    public DetailAstImpl visitThrowsList(JavaLanguageParser.ThrowsListContext ctx) {
440        final DetailAstImpl throwsRoot = create(ctx.LITERAL_THROWS());
441        throwsRoot.addChild(visit(ctx.qualifiedNameList()));
442        return throwsRoot;
443    }
444
445    @Override
446    public DetailAstImpl visitConstructorDeclaration(
447            JavaLanguageParser.ConstructorDeclarationContext ctx) {
448        final DetailAstImpl constructorDeclaration = createImaginary(TokenTypes.CTOR_DEF);
449        constructorDeclaration.addChild(createModifiers(ctx.mods));
450        processChildren(constructorDeclaration, ctx.children);
451        return constructorDeclaration;
452    }
453
454    @Override
455    public DetailAstImpl visitFieldDeclaration(JavaLanguageParser.FieldDeclarationContext ctx) {
456        final DetailAstImpl dummyNode = new DetailAstImpl();
457        // Since the TYPE AST is built by visitVariableDeclarator(), we skip it here (child [0])
458        // We also append the SEMI token to the first child [size() - 1],
459        // until https://github.com/checkstyle/checkstyle/issues/3151
460        processChildren(dummyNode, ctx.children.subList(1, ctx.children.size() - 1));
461        dummyNode.getFirstChild().addChild(create(ctx.SEMI()));
462        return dummyNode.getFirstChild();
463    }
464
465    @Override
466    public DetailAstImpl visitInterfaceBodyDeclaration(
467            JavaLanguageParser.InterfaceBodyDeclarationContext ctx) {
468        final DetailAstImpl returnTree;
469        if (ctx.SEMI() == null) {
470            returnTree = visit(ctx.interfaceMemberDeclaration());
471        }
472        else {
473            returnTree = create(ctx.SEMI());
474        }
475        return returnTree;
476    }
477
478    @Override
479    public DetailAstImpl visitInterfaceMethodDeclaration(
480            JavaLanguageParser.InterfaceMethodDeclarationContext ctx) {
481        final DetailAstImpl methodDef = createImaginary(TokenTypes.METHOD_DEF);
482        methodDef.addChild(createModifiers(ctx.mods));
483
484        // Process all children except C style array declarators and modifiers
485        final List<ParseTree> children = ctx.children
486                .stream()
487                .filter(child -> !(child instanceof JavaLanguageParser.ArrayDeclaratorContext))
488                .collect(Collectors.toUnmodifiableList());
489        processChildren(methodDef, children);
490
491        // We add C style array declarator brackets to TYPE ast
492        final DetailAstImpl typeAst = (DetailAstImpl) methodDef.findFirstToken(TokenTypes.TYPE);
493        ctx.cStyleArrDec.forEach(child -> typeAst.addChild(visit(child)));
494
495        return methodDef;
496    }
497
498    @Override
499    public DetailAstImpl visitVariableDeclarators(
500            JavaLanguageParser.VariableDeclaratorsContext ctx) {
501        return flattenedTree(ctx);
502    }
503
504    @Override
505    public DetailAstImpl visitVariableDeclarator(
506            JavaLanguageParser.VariableDeclaratorContext ctx) {
507        final DetailAstImpl variableDef = createImaginary(TokenTypes.VARIABLE_DEF);
508        variableDef.addChild(createModifiers(ctx.mods));
509
510        final DetailAstImpl type = visit(ctx.type);
511        variableDef.addChild(type);
512        variableDef.addChild(visit(ctx.id()));
513
514        // Add C style array declarator brackets to TYPE ast
515        ctx.arrayDeclarator().forEach(child -> type.addChild(visit(child)));
516
517        // If this is an assignment statement, ASSIGN becomes the parent of EXPR
518        final TerminalNode assignNode = ctx.ASSIGN();
519        if (assignNode != null) {
520            final DetailAstImpl assign = create(assignNode);
521            variableDef.addChild(assign);
522            assign.addChild(visit(ctx.variableInitializer()));
523        }
524        return variableDef;
525    }
526
527    @Override
528    public DetailAstImpl visitVariableDeclaratorId(
529            JavaLanguageParser.VariableDeclaratorIdContext ctx) {
530        final DetailAstImpl root = new DetailAstImpl();
531        root.addChild(createModifiers(ctx.mods));
532        final DetailAstImpl type = visit(ctx.type);
533        root.addChild(type);
534
535        final DetailAstImpl declaratorId;
536        if (ctx.LITERAL_THIS() == null) {
537            declaratorId = visit(ctx.qualifiedName());
538        }
539        else if (ctx.DOT() == null) {
540            declaratorId = create(ctx.LITERAL_THIS());
541        }
542        else {
543            declaratorId = create(ctx.DOT());
544            declaratorId.addChild(visit(ctx.qualifiedName()));
545            declaratorId.addChild(create(ctx.LITERAL_THIS()));
546        }
547
548        root.addChild(declaratorId);
549        ctx.arrayDeclarator().forEach(child -> type.addChild(visit(child)));
550
551        return root.getFirstChild();
552    }
553
554    @Override
555    public DetailAstImpl visitArrayInitializer(JavaLanguageParser.ArrayInitializerContext ctx) {
556        final DetailAstImpl arrayInitializer = create(TokenTypes.ARRAY_INIT, ctx.start);
557        // ARRAY_INIT was child[0]
558        processChildren(arrayInitializer, ctx.children.subList(1, ctx.children.size()));
559        return arrayInitializer;
560    }
561
562    @Override
563    public DetailAstImpl visitClassOrInterfaceType(
564            JavaLanguageParser.ClassOrInterfaceTypeContext ctx) {
565        final DetailAstPair currentAST = new DetailAstPair();
566        DetailAstPair.addAstChild(currentAST, visit(ctx.id()));
567        DetailAstPair.addAstChild(currentAST, visit(ctx.typeArguments()));
568
569        // This is how we build the annotations/ qualified name/ type parameters tree
570        for (ParserRuleContext extendedContext : ctx.extended) {
571            final DetailAstImpl dot = create(extendedContext.start);
572            DetailAstPair.makeAstRoot(currentAST, dot);
573            extendedContext.children
574                .forEach(child -> DetailAstPair.addAstChild(currentAST, visit(child)));
575        }
576
577        // Create imaginary 'TYPE' parent if specified
578        final DetailAstImpl returnTree;
579        if (ctx.createImaginaryNode) {
580            returnTree = createImaginary(TokenTypes.TYPE);
581            returnTree.addChild(currentAST.root);
582        }
583        else {
584            returnTree = currentAST.root;
585        }
586        return returnTree;
587    }
588
589    @Override
590    public DetailAstImpl visitSimpleTypeArgument(
591            JavaLanguageParser.SimpleTypeArgumentContext ctx) {
592        final DetailAstImpl typeArgument =
593                createImaginary(TokenTypes.TYPE_ARGUMENT);
594        typeArgument.addChild(visit(ctx.typeType()));
595        return typeArgument;
596    }
597
598    @Override
599    public DetailAstImpl visitWildCardTypeArgument(
600            JavaLanguageParser.WildCardTypeArgumentContext ctx) {
601        final DetailAstImpl typeArgument = createImaginary(TokenTypes.TYPE_ARGUMENT);
602        typeArgument.addChild(visit(ctx.annotations()));
603        typeArgument.addChild(create(TokenTypes.WILDCARD_TYPE,
604                (Token) ctx.QUESTION().getPayload()));
605
606        if (ctx.upperBound != null) {
607            final DetailAstImpl upperBound = create(TokenTypes.TYPE_UPPER_BOUNDS, ctx.upperBound);
608            upperBound.addChild(visit(ctx.typeType()));
609            typeArgument.addChild(upperBound);
610        }
611        else if (ctx.lowerBound != null) {
612            final DetailAstImpl lowerBound = create(TokenTypes.TYPE_LOWER_BOUNDS, ctx.lowerBound);
613            lowerBound.addChild(visit(ctx.typeType()));
614            typeArgument.addChild(lowerBound);
615        }
616
617        return typeArgument;
618    }
619
620    @Override
621    public DetailAstImpl visitQualifiedNameList(JavaLanguageParser.QualifiedNameListContext ctx) {
622        return flattenedTree(ctx);
623    }
624
625    @Override
626    public DetailAstImpl visitFormalParameters(JavaLanguageParser.FormalParametersContext ctx) {
627        final DetailAstImpl lparen = create(ctx.LPAREN());
628
629        // We make a "PARAMETERS" node whether parameters exist or not
630        if (ctx.formalParameterList() == null) {
631            addLastSibling(lparen, createImaginary(TokenTypes.PARAMETERS));
632        }
633        else {
634            addLastSibling(lparen, visit(ctx.formalParameterList()));
635        }
636        addLastSibling(lparen, create(ctx.RPAREN()));
637        return lparen;
638    }
639
640    @Override
641    public DetailAstImpl visitFormalParameterList(
642            JavaLanguageParser.FormalParameterListContext ctx) {
643        final DetailAstImpl parameters = createImaginary(TokenTypes.PARAMETERS);
644        processChildren(parameters, ctx.children);
645        return parameters;
646    }
647
648    @Override
649    public DetailAstImpl visitFormalParameter(JavaLanguageParser.FormalParameterContext ctx) {
650        final DetailAstImpl variableDeclaratorId =
651                visitVariableDeclaratorId(ctx.variableDeclaratorId());
652        final DetailAstImpl parameterDef = createImaginary(TokenTypes.PARAMETER_DEF);
653        parameterDef.addChild(variableDeclaratorId);
654        return parameterDef;
655    }
656
657    @Override
658    public DetailAstImpl visitLastFormalParameter(
659            JavaLanguageParser.LastFormalParameterContext ctx) {
660        final DetailAstImpl parameterDef =
661                createImaginary(TokenTypes.PARAMETER_DEF);
662        parameterDef.addChild(visit(ctx.variableDeclaratorId()));
663        final DetailAstImpl ident = (DetailAstImpl) parameterDef.findFirstToken(TokenTypes.IDENT);
664        ident.addPreviousSibling(create(ctx.ELLIPSIS()));
665        // We attach annotations on ellipses in varargs to the 'TYPE' ast
666        final DetailAstImpl type = (DetailAstImpl) parameterDef.findFirstToken(TokenTypes.TYPE);
667        type.addChild(visit(ctx.annotations()));
668        return parameterDef;
669    }
670
671    @Override
672    public DetailAstImpl visitQualifiedName(JavaLanguageParser.QualifiedNameContext ctx) {
673        final DetailAstImpl ast = visit(ctx.id());
674        final DetailAstPair currentAst = new DetailAstPair();
675        DetailAstPair.addAstChild(currentAst, ast);
676
677        for (ParserRuleContext extendedContext : ctx.extended) {
678            final DetailAstImpl dot = create(extendedContext.start);
679            DetailAstPair.makeAstRoot(currentAst, dot);
680            final List<ParseTree> childList = extendedContext
681                    .children.subList(1, extendedContext.children.size());
682            processChildren(dot, childList);
683        }
684        return currentAst.getRoot();
685    }
686
687    @Override
688    public DetailAstImpl visitLiteral(JavaLanguageParser.LiteralContext ctx) {
689        return flattenedTree(ctx);
690    }
691
692    @Override
693    public DetailAstImpl visitIntegerLiteral(JavaLanguageParser.IntegerLiteralContext ctx) {
694        final int[] longTypes = {
695            JavaLanguageLexer.DECIMAL_LITERAL_LONG,
696            JavaLanguageLexer.HEX_LITERAL_LONG,
697            JavaLanguageLexer.OCT_LITERAL_LONG,
698            JavaLanguageLexer.BINARY_LITERAL_LONG,
699        };
700
701        final int tokenType;
702        if (TokenUtil.isOfType(ctx.start.getType(), longTypes)) {
703            tokenType = TokenTypes.NUM_LONG;
704        }
705        else {
706            tokenType = TokenTypes.NUM_INT;
707        }
708
709        return create(tokenType, ctx.start);
710    }
711
712    @Override
713    public DetailAstImpl visitFloatLiteral(JavaLanguageParser.FloatLiteralContext ctx) {
714        final DetailAstImpl floatLiteral;
715        if (TokenUtil.isOfType(ctx.start.getType(),
716                JavaLanguageLexer.DOUBLE_LITERAL, JavaLanguageLexer.HEX_DOUBLE_LITERAL)) {
717            floatLiteral = create(TokenTypes.NUM_DOUBLE, ctx.start);
718        }
719        else {
720            floatLiteral = create(TokenTypes.NUM_FLOAT, ctx.start);
721        }
722        return floatLiteral;
723    }
724
725    @Override
726    public DetailAstImpl visitTextBlockLiteral(JavaLanguageParser.TextBlockLiteralContext ctx) {
727        final DetailAstImpl textBlockLiteralBegin = create(ctx.TEXT_BLOCK_LITERAL_BEGIN());
728        textBlockLiteralBegin.addChild(create(ctx.TEXT_BLOCK_CONTENT()));
729        textBlockLiteralBegin.addChild(create(ctx.TEXT_BLOCK_LITERAL_END()));
730        return textBlockLiteralBegin;
731    }
732
733    @Override
734    public DetailAstImpl visitAnnotations(JavaLanguageParser.AnnotationsContext ctx) {
735        final DetailAstImpl annotations;
736
737        if (!ctx.createImaginaryNode && ctx.anno.isEmpty()) {
738            // There are no annotations, and we don't want to create the empty node
739            annotations = null;
740        }
741        else {
742            // There are annotations, or we just want the empty node
743            annotations = createImaginary(TokenTypes.ANNOTATIONS);
744            processChildren(annotations, ctx.anno);
745        }
746
747        return annotations;
748    }
749
750    @Override
751    public DetailAstImpl visitAnnotation(JavaLanguageParser.AnnotationContext ctx) {
752        final DetailAstImpl annotation = createImaginary(TokenTypes.ANNOTATION);
753        processChildren(annotation, ctx.children);
754        return annotation;
755    }
756
757    @Override
758    public DetailAstImpl visitElementValuePairs(JavaLanguageParser.ElementValuePairsContext ctx) {
759        return flattenedTree(ctx);
760    }
761
762    @Override
763    public DetailAstImpl visitElementValuePair(JavaLanguageParser.ElementValuePairContext ctx) {
764        final DetailAstImpl elementValuePair =
765                createImaginary(TokenTypes.ANNOTATION_MEMBER_VALUE_PAIR);
766        processChildren(elementValuePair, ctx.children);
767        return elementValuePair;
768    }
769
770    @Override
771    public DetailAstImpl visitElementValue(JavaLanguageParser.ElementValueContext ctx) {
772        return flattenedTree(ctx);
773    }
774
775    @Override
776    public DetailAstImpl visitElementValueArrayInitializer(
777            JavaLanguageParser.ElementValueArrayInitializerContext ctx) {
778        final DetailAstImpl arrayInit =
779                create(TokenTypes.ANNOTATION_ARRAY_INIT, (Token) ctx.LCURLY().getPayload());
780        processChildren(arrayInit, ctx.children.subList(1, ctx.children.size()));
781        return arrayInit;
782    }
783
784    @Override
785    public DetailAstImpl visitAnnotationTypeDeclaration(
786            JavaLanguageParser.AnnotationTypeDeclarationContext ctx) {
787        return createTypeDeclaration(ctx, TokenTypes.ANNOTATION_DEF, ctx.mods);
788    }
789
790    @Override
791    public DetailAstImpl visitAnnotationTypeBody(
792            JavaLanguageParser.AnnotationTypeBodyContext ctx) {
793        final DetailAstImpl objBlock = createImaginary(TokenTypes.OBJBLOCK);
794        processChildren(objBlock, ctx.children);
795        return objBlock;
796    }
797
798    @Override
799    public DetailAstImpl visitAnnotationTypeElementDeclaration(
800            JavaLanguageParser.AnnotationTypeElementDeclarationContext ctx) {
801        final DetailAstImpl returnTree;
802        if (ctx.SEMI() == null) {
803            returnTree = visit(ctx.annotationTypeElementRest());
804        }
805        else {
806            returnTree = create(ctx.SEMI());
807        }
808        return returnTree;
809    }
810
811    @Override
812    public DetailAstImpl visitAnnotationField(JavaLanguageParser.AnnotationFieldContext ctx) {
813        final DetailAstImpl dummyNode = new DetailAstImpl();
814        // Since the TYPE AST is built by visitAnnotationMethodOrConstantRest(), we skip it
815        // here (child [0])
816        processChildren(dummyNode, Collections.singletonList(ctx.children.get(1)));
817        // We also append the SEMI token to the first child [size() - 1],
818        // until https://github.com/checkstyle/checkstyle/issues/3151
819        dummyNode.getFirstChild().addChild(create(ctx.SEMI()));
820        return dummyNode.getFirstChild();
821    }
822
823    @Override
824    public DetailAstImpl visitAnnotationType(JavaLanguageParser.AnnotationTypeContext ctx) {
825        return flattenedTree(ctx);
826    }
827
828    @Override
829    public DetailAstImpl visitAnnotationMethodRest(
830            JavaLanguageParser.AnnotationMethodRestContext ctx) {
831        final DetailAstImpl annotationFieldDef =
832                createImaginary(TokenTypes.ANNOTATION_FIELD_DEF);
833        annotationFieldDef.addChild(createModifiers(ctx.mods));
834        annotationFieldDef.addChild(visit(ctx.type));
835
836        // Process all children except C style array declarators
837        processChildren(annotationFieldDef, ctx.children.stream()
838                .filter(child -> !(child instanceof JavaLanguageParser.ArrayDeclaratorContext))
839                .collect(Collectors.toUnmodifiableList()));
840
841        // We add C style array declarator brackets to TYPE ast
842        final DetailAstImpl typeAst =
843                (DetailAstImpl) annotationFieldDef.findFirstToken(TokenTypes.TYPE);
844        ctx.cStyleArrDec.forEach(child -> typeAst.addChild(visit(child)));
845
846        return annotationFieldDef;
847    }
848
849    @Override
850    public DetailAstImpl visitDefaultValue(JavaLanguageParser.DefaultValueContext ctx) {
851        final DetailAstImpl defaultValue = create(ctx.LITERAL_DEFAULT());
852        defaultValue.addChild(visit(ctx.elementValue()));
853        return defaultValue;
854    }
855
856    @Override
857    public DetailAstImpl visitConstructorBlock(JavaLanguageParser.ConstructorBlockContext ctx) {
858        final DetailAstImpl slist = create(TokenTypes.SLIST, ctx.start);
859        // SLIST was child [0]
860        processChildren(slist, ctx.children.subList(1, ctx.children.size()));
861        return slist;
862    }
863
864    @Override
865    public DetailAstImpl visitExplicitCtorCall(JavaLanguageParser.ExplicitCtorCallContext ctx) {
866        final DetailAstImpl root;
867        if (ctx.LITERAL_THIS() == null) {
868            root = create(TokenTypes.SUPER_CTOR_CALL, (Token) ctx.LITERAL_SUPER().getPayload());
869        }
870        else {
871            root = create(TokenTypes.CTOR_CALL, (Token) ctx.LITERAL_THIS().getPayload());
872        }
873        root.addChild(visit(ctx.typeArguments()));
874        root.addChild(visit(ctx.arguments()));
875        root.addChild(create(ctx.SEMI()));
876        return root;
877    }
878
879    @Override
880    public DetailAstImpl visitPrimaryCtorCall(JavaLanguageParser.PrimaryCtorCallContext ctx) {
881        final DetailAstImpl primaryCtorCall = create(TokenTypes.SUPER_CTOR_CALL,
882                (Token) ctx.LITERAL_SUPER().getPayload());
883        // filter 'LITERAL_SUPER'
884        processChildren(primaryCtorCall, ctx.children.stream()
885                   .filter(child -> !child.equals(ctx.LITERAL_SUPER()))
886                   .collect(Collectors.toUnmodifiableList()));
887        return primaryCtorCall;
888    }
889
890    @Override
891    public DetailAstImpl visitBlock(JavaLanguageParser.BlockContext ctx) {
892        final DetailAstImpl slist = create(TokenTypes.SLIST, ctx.start);
893        // SLIST was child [0]
894        processChildren(slist, ctx.children.subList(1, ctx.children.size()));
895        return slist;
896    }
897
898    @Override
899    public DetailAstImpl visitLocalVar(JavaLanguageParser.LocalVarContext ctx) {
900        return flattenedTree(ctx);
901    }
902
903    @Override
904    public DetailAstImpl visitBlockStat(JavaLanguageParser.BlockStatContext ctx) {
905        return flattenedTree(ctx);
906    }
907
908    @Override
909    public DetailAstImpl visitAssertExp(JavaLanguageParser.AssertExpContext ctx) {
910        final DetailAstImpl assertExp = create(ctx.ASSERT());
911        // child[0] is 'ASSERT'
912        processChildren(assertExp, ctx.children.subList(1, ctx.children.size()));
913        return assertExp;
914    }
915
916    @Override
917    public DetailAstImpl visitIfStat(JavaLanguageParser.IfStatContext ctx) {
918        final DetailAstImpl ifStat = create(ctx.LITERAL_IF());
919        // child[0] is 'LITERAL_IF'
920        processChildren(ifStat, ctx.children.subList(1, ctx.children.size()));
921        return ifStat;
922    }
923
924    @Override
925    public DetailAstImpl visitForStat(JavaLanguageParser.ForStatContext ctx) {
926        final DetailAstImpl forInit = create(ctx.start);
927        // child[0] is LITERAL_FOR
928        processChildren(forInit, ctx.children.subList(1, ctx.children.size()));
929        return forInit;
930    }
931
932    @Override
933    public DetailAstImpl visitWhileStat(JavaLanguageParser.WhileStatContext ctx) {
934        final DetailAstImpl whileStatement = create(ctx.start);
935        // 'LITERAL_WHILE' is child[0]
936        processChildren(whileStatement, ctx.children.subList(1, ctx.children.size()));
937        return whileStatement;
938    }
939
940    @Override
941    public DetailAstImpl visitDoStat(JavaLanguageParser.DoStatContext ctx) {
942        final DetailAstImpl doStatement = create(ctx.start);
943        // 'LITERAL_DO' is child[0]
944        doStatement.addChild(visit(ctx.statement()));
945        // We make 'LITERAL_WHILE' into 'DO_WHILE'
946        doStatement.addChild(create(TokenTypes.DO_WHILE, (Token) ctx.LITERAL_WHILE().getPayload()));
947        doStatement.addChild(visit(ctx.parExpression()));
948        doStatement.addChild(create(ctx.SEMI()));
949        return doStatement;
950    }
951
952    @Override
953    public DetailAstImpl visitTryStat(JavaLanguageParser.TryStatContext ctx) {
954        final DetailAstImpl tryStat = create(ctx.start);
955        // child[0] is 'LITERAL_TRY'
956        processChildren(tryStat, ctx.children.subList(1, ctx.children.size()));
957        return tryStat;
958    }
959
960    @Override
961    public DetailAstImpl visitTryWithResourceStat(
962            JavaLanguageParser.TryWithResourceStatContext ctx) {
963        final DetailAstImpl tryWithResources = create(ctx.LITERAL_TRY());
964        // child[0] is 'LITERAL_TRY'
965        processChildren(tryWithResources, ctx.children.subList(1, ctx.children.size()));
966        return tryWithResources;
967    }
968
969    @Override
970    public DetailAstImpl visitYieldStat(JavaLanguageParser.YieldStatContext ctx) {
971        final DetailAstImpl yieldParent = create(ctx.LITERAL_YIELD());
972        // LITERAL_YIELD is child[0]
973        processChildren(yieldParent, ctx.children.subList(1, ctx.children.size()));
974        return yieldParent;
975    }
976
977    @Override
978    public DetailAstImpl visitSyncStat(JavaLanguageParser.SyncStatContext ctx) {
979        final DetailAstImpl syncStatement = create(ctx.start);
980        // child[0] is 'LITERAL_SYNCHRONIZED'
981        processChildren(syncStatement, ctx.children.subList(1, ctx.children.size()));
982        return syncStatement;
983    }
984
985    @Override
986    public DetailAstImpl visitReturnStat(JavaLanguageParser.ReturnStatContext ctx) {
987        final DetailAstImpl returnStat = create(ctx.LITERAL_RETURN());
988        // child[0] is 'LITERAL_RETURN'
989        processChildren(returnStat, ctx.children.subList(1, ctx.children.size()));
990        return returnStat;
991    }
992
993    @Override
994    public DetailAstImpl visitThrowStat(JavaLanguageParser.ThrowStatContext ctx) {
995        final DetailAstImpl throwStat = create(ctx.LITERAL_THROW());
996        // child[0] is 'LITERAL_THROW'
997        processChildren(throwStat, ctx.children.subList(1, ctx.children.size()));
998        return throwStat;
999    }
1000
1001    @Override
1002    public DetailAstImpl visitBreakStat(JavaLanguageParser.BreakStatContext ctx) {
1003        final DetailAstImpl literalBreak = create(ctx.LITERAL_BREAK());
1004        // child[0] is 'LITERAL_BREAK'
1005        processChildren(literalBreak, ctx.children.subList(1, ctx.children.size()));
1006        return literalBreak;
1007    }
1008
1009    @Override
1010    public DetailAstImpl visitContinueStat(JavaLanguageParser.ContinueStatContext ctx) {
1011        final DetailAstImpl continueStat = create(ctx.LITERAL_CONTINUE());
1012        // child[0] is 'LITERAL_CONTINUE'
1013        processChildren(continueStat, ctx.children.subList(1, ctx.children.size()));
1014        return continueStat;
1015    }
1016
1017    @Override
1018    public DetailAstImpl visitEmptyStat(JavaLanguageParser.EmptyStatContext ctx) {
1019        return create(TokenTypes.EMPTY_STAT, ctx.start);
1020    }
1021
1022    @Override
1023    public DetailAstImpl visitExpStat(JavaLanguageParser.ExpStatContext ctx) {
1024        final DetailAstImpl expStatRoot = visit(ctx.statementExpression);
1025        addLastSibling(expStatRoot, create(ctx.SEMI()));
1026        return expStatRoot;
1027    }
1028
1029    @Override
1030    public DetailAstImpl visitLabelStat(JavaLanguageParser.LabelStatContext ctx) {
1031        final DetailAstImpl labelStat = create(TokenTypes.LABELED_STAT,
1032                (Token) ctx.COLON().getPayload());
1033        labelStat.addChild(visit(ctx.id()));
1034        labelStat.addChild(visit(ctx.statement()));
1035        return labelStat;
1036    }
1037
1038    @Override
1039    public DetailAstImpl visitSwitchExpressionOrStatement(
1040            JavaLanguageParser.SwitchExpressionOrStatementContext ctx) {
1041        final DetailAstImpl switchStat = create(ctx.LITERAL_SWITCH());
1042        switchStat.addChild(visit(ctx.parExpression()));
1043        switchStat.addChild(create(ctx.LCURLY()));
1044        switchStat.addChild(visit(ctx.switchBlock()));
1045        switchStat.addChild(create(ctx.RCURLY()));
1046        return switchStat;
1047    }
1048
1049    @Override
1050    public DetailAstImpl visitSwitchRules(JavaLanguageParser.SwitchRulesContext ctx) {
1051        final DetailAstImpl dummyRoot = new DetailAstImpl();
1052        ctx.switchLabeledRule().forEach(switchLabeledRuleContext -> {
1053            final DetailAstImpl switchRule = visit(switchLabeledRuleContext);
1054            final DetailAstImpl switchRuleParent = createImaginary(TokenTypes.SWITCH_RULE);
1055            switchRuleParent.addChild(switchRule);
1056            dummyRoot.addChild(switchRuleParent);
1057        });
1058        return dummyRoot.getFirstChild();
1059    }
1060
1061    @Override
1062    public DetailAstImpl visitSwitchBlocks(JavaLanguageParser.SwitchBlocksContext ctx) {
1063        final DetailAstImpl dummyRoot = new DetailAstImpl();
1064        ctx.groups.forEach(group -> dummyRoot.addChild(visit(group)));
1065
1066        // Add any empty switch labels to end of statement in one 'CASE_GROUP'
1067        if (!ctx.emptyLabels.isEmpty()) {
1068            final DetailAstImpl emptyLabelParent =
1069                    createImaginary(TokenTypes.CASE_GROUP);
1070            ctx.emptyLabels.forEach(label -> emptyLabelParent.addChild(visit(label)));
1071            dummyRoot.addChild(emptyLabelParent);
1072        }
1073        return dummyRoot.getFirstChild();
1074    }
1075
1076    @Override
1077    public DetailAstImpl visitSwitchLabeledExpression(
1078            JavaLanguageParser.SwitchLabeledExpressionContext ctx) {
1079        return flattenedTree(ctx);
1080    }
1081
1082    @Override
1083    public DetailAstImpl visitSwitchLabeledBlock(
1084            JavaLanguageParser.SwitchLabeledBlockContext ctx) {
1085        return flattenedTree(ctx);
1086    }
1087
1088    @Override
1089    public DetailAstImpl visitSwitchLabeledThrow(
1090            JavaLanguageParser.SwitchLabeledThrowContext ctx) {
1091        final DetailAstImpl switchLabel = visit(ctx.switchLabel());
1092        addLastSibling(switchLabel, create(ctx.LAMBDA()));
1093        final DetailAstImpl literalThrow = create(ctx.LITERAL_THROW());
1094        literalThrow.addChild(visit(ctx.expression()));
1095        literalThrow.addChild(create(ctx.SEMI()));
1096        addLastSibling(switchLabel, literalThrow);
1097        return switchLabel;
1098    }
1099
1100    @Override
1101    public DetailAstImpl visitElseStat(JavaLanguageParser.ElseStatContext ctx) {
1102        final DetailAstImpl elseStat = create(ctx.LITERAL_ELSE());
1103        // child[0] is 'LITERAL_ELSE'
1104        processChildren(elseStat, ctx.children.subList(1, ctx.children.size()));
1105        return elseStat;
1106    }
1107
1108    @Override
1109    public DetailAstImpl visitCatchClause(JavaLanguageParser.CatchClauseContext ctx) {
1110        final DetailAstImpl catchClause = create(TokenTypes.LITERAL_CATCH,
1111                (Token) ctx.LITERAL_CATCH().getPayload());
1112        // 'LITERAL_CATCH' is child[0]
1113        processChildren(catchClause, ctx.children.subList(1, ctx.children.size()));
1114        return catchClause;
1115    }
1116
1117    @Override
1118    public DetailAstImpl visitCatchParameter(JavaLanguageParser.CatchParameterContext ctx) {
1119        final DetailAstImpl catchParameterDef = createImaginary(TokenTypes.PARAMETER_DEF);
1120        catchParameterDef.addChild(createModifiers(ctx.mods));
1121        // filter mods
1122        processChildren(catchParameterDef, ctx.children.stream()
1123                .filter(child -> !(child instanceof JavaLanguageParser.VariableModifierContext))
1124                .collect(Collectors.toUnmodifiableList()));
1125        return catchParameterDef;
1126    }
1127
1128    @Override
1129    public DetailAstImpl visitCatchType(JavaLanguageParser.CatchTypeContext ctx) {
1130        final DetailAstImpl type = createImaginary(TokenTypes.TYPE);
1131        processChildren(type, ctx.children);
1132        return type;
1133    }
1134
1135    @Override
1136    public DetailAstImpl visitFinallyBlock(JavaLanguageParser.FinallyBlockContext ctx) {
1137        final DetailAstImpl finallyBlock = create(ctx.LITERAL_FINALLY());
1138        // child[0] is 'LITERAL_FINALLY'
1139        processChildren(finallyBlock, ctx.children.subList(1, ctx.children.size()));
1140        return finallyBlock;
1141    }
1142
1143    @Override
1144    public DetailAstImpl visitResourceSpecification(
1145            JavaLanguageParser.ResourceSpecificationContext ctx) {
1146        final DetailAstImpl resourceSpecification =
1147                createImaginary(TokenTypes.RESOURCE_SPECIFICATION);
1148        processChildren(resourceSpecification, ctx.children);
1149        return resourceSpecification;
1150    }
1151
1152    @Override
1153    public DetailAstImpl visitResources(JavaLanguageParser.ResourcesContext ctx) {
1154        final DetailAstImpl firstResource = visit(ctx.resource(0));
1155        final DetailAstImpl resources = createImaginary(TokenTypes.RESOURCES);
1156        resources.addChild(firstResource);
1157        processChildren(resources, ctx.children.subList(1, ctx.children.size()));
1158        return resources;
1159    }
1160
1161    @Override
1162    public DetailAstImpl visitResourceDeclaration(
1163            JavaLanguageParser.ResourceDeclarationContext ctx) {
1164        final DetailAstImpl resource = createImaginary(TokenTypes.RESOURCE);
1165        resource.addChild(visit(ctx.variableDeclaratorId()));
1166
1167        final DetailAstImpl assign = create(ctx.ASSIGN());
1168        resource.addChild(assign);
1169        assign.addChild(visit(ctx.expression()));
1170        return resource;
1171    }
1172
1173    @Override
1174    public DetailAstImpl visitVariableAccess(JavaLanguageParser.VariableAccessContext ctx) {
1175        final DetailAstImpl resource = createImaginary(TokenTypes.RESOURCE);
1176
1177        final DetailAstImpl childNode;
1178        if (ctx.LITERAL_THIS() == null) {
1179            childNode = visit(ctx.id());
1180        }
1181        else {
1182            childNode = create(ctx.LITERAL_THIS());
1183        }
1184
1185        if (ctx.accessList.isEmpty()) {
1186            resource.addChild(childNode);
1187        }
1188        else {
1189            final DetailAstPair currentAst = new DetailAstPair();
1190            ctx.accessList.forEach(fieldAccess -> {
1191                DetailAstPair.addAstChild(currentAst, visit(fieldAccess.expr()));
1192                DetailAstPair.makeAstRoot(currentAst, create(fieldAccess.DOT()));
1193            });
1194            resource.addChild(currentAst.getRoot());
1195            resource.getFirstChild().addChild(childNode);
1196        }
1197        return resource;
1198    }
1199
1200    @Override
1201    public DetailAstImpl visitSwitchBlockStatementGroup(
1202            JavaLanguageParser.SwitchBlockStatementGroupContext ctx) {
1203        final DetailAstImpl caseGroup = createImaginary(TokenTypes.CASE_GROUP);
1204        processChildren(caseGroup, ctx.switchLabel());
1205        final DetailAstImpl sList = createImaginary(TokenTypes.SLIST);
1206        processChildren(sList, ctx.slists);
1207        caseGroup.addChild(sList);
1208        return caseGroup;
1209    }
1210
1211    @Override
1212    public DetailAstImpl visitCaseLabel(JavaLanguageParser.CaseLabelContext ctx) {
1213        final DetailAstImpl caseLabel = create(ctx.LITERAL_CASE());
1214        // child [0] is 'LITERAL_CASE'
1215        processChildren(caseLabel, ctx.children.subList(1, ctx.children.size()));
1216        return caseLabel;
1217    }
1218
1219    @Override
1220    public DetailAstImpl visitDefaultLabel(JavaLanguageParser.DefaultLabelContext ctx) {
1221        final DetailAstImpl defaultLabel = create(ctx.LITERAL_DEFAULT());
1222        if (ctx.COLON() != null) {
1223            defaultLabel.addChild(create(ctx.COLON()));
1224        }
1225        return defaultLabel;
1226    }
1227
1228    @Override
1229    public DetailAstImpl visitCaseConstants(JavaLanguageParser.CaseConstantsContext ctx) {
1230        return flattenedTree(ctx);
1231    }
1232
1233    @Override
1234    public DetailAstImpl visitCaseConstant(JavaLanguageParser.CaseConstantContext ctx) {
1235        return flattenedTree(ctx);
1236    }
1237
1238    @Override
1239    public DetailAstImpl visitEnhancedFor(JavaLanguageParser.EnhancedForContext ctx) {
1240        final DetailAstImpl leftParen = create(ctx.LPAREN());
1241        final DetailAstImpl enhancedForControl =
1242                 visit(ctx.getChild(1));
1243        final DetailAstImpl forEachClause = createImaginary(TokenTypes.FOR_EACH_CLAUSE);
1244        forEachClause.addChild(enhancedForControl);
1245        addLastSibling(leftParen, forEachClause);
1246        addLastSibling(leftParen, create(ctx.RPAREN()));
1247        return leftParen;
1248    }
1249
1250    @Override
1251    public DetailAstImpl visitForFor(JavaLanguageParser.ForForContext ctx) {
1252        final DetailAstImpl dummyRoot = new DetailAstImpl();
1253        dummyRoot.addChild(create(ctx.LPAREN()));
1254
1255        if (ctx.forInit() == null) {
1256            final DetailAstImpl imaginaryForInitParent =
1257                    createImaginary(TokenTypes.FOR_INIT);
1258            dummyRoot.addChild(imaginaryForInitParent);
1259        }
1260        else {
1261            dummyRoot.addChild(visit(ctx.forInit()));
1262        }
1263
1264        dummyRoot.addChild(create(ctx.SEMI(0)));
1265
1266        final DetailAstImpl forCondParent = createImaginary(TokenTypes.FOR_CONDITION);
1267        forCondParent.addChild(visit(ctx.forCond));
1268        dummyRoot.addChild(forCondParent);
1269        dummyRoot.addChild(create(ctx.SEMI(1)));
1270
1271        final DetailAstImpl forItParent = createImaginary(TokenTypes.FOR_ITERATOR);
1272        forItParent.addChild(visit(ctx.forUpdate));
1273        dummyRoot.addChild(forItParent);
1274
1275        dummyRoot.addChild(create(ctx.RPAREN()));
1276
1277        return dummyRoot.getFirstChild();
1278    }
1279
1280    @Override
1281    public DetailAstImpl visitForInit(JavaLanguageParser.ForInitContext ctx) {
1282        final DetailAstImpl forInit = createImaginary(TokenTypes.FOR_INIT);
1283        processChildren(forInit, ctx.children);
1284        return forInit;
1285    }
1286
1287    @Override
1288    public DetailAstImpl visitEnhancedForControl(
1289            JavaLanguageParser.EnhancedForControlContext ctx) {
1290        final DetailAstImpl variableDeclaratorId =
1291                 visit(ctx.variableDeclaratorId());
1292        final DetailAstImpl variableDef = createImaginary(TokenTypes.VARIABLE_DEF);
1293        variableDef.addChild(variableDeclaratorId);
1294
1295        addLastSibling(variableDef, create(ctx.COLON()));
1296        addLastSibling(variableDef, visit(ctx.expression()));
1297        return variableDef;
1298    }
1299
1300    @Override
1301    public DetailAstImpl visitEnhancedForControlWithRecordPattern(
1302            JavaLanguageParser.EnhancedForControlWithRecordPatternContext ctx) {
1303        final DetailAstImpl recordPattern =
1304                 visit(ctx.pattern());
1305        addLastSibling(recordPattern, create(ctx.COLON()));
1306        addLastSibling(recordPattern, visit(ctx.expression()));
1307        return recordPattern;
1308    }
1309
1310    @Override
1311    public DetailAstImpl visitParExpression(JavaLanguageParser.ParExpressionContext ctx) {
1312        return flattenedTree(ctx);
1313    }
1314
1315    @Override
1316    public DetailAstImpl visitExpressionList(JavaLanguageParser.ExpressionListContext ctx) {
1317        final DetailAstImpl elist = createImaginary(TokenTypes.ELIST);
1318        processChildren(elist, ctx.children);
1319        return elist;
1320    }
1321
1322    @Override
1323    public DetailAstImpl visitExpression(JavaLanguageParser.ExpressionContext ctx) {
1324        return buildExpressionNode(ctx.expr());
1325    }
1326
1327    @Override
1328    public DetailAstImpl visitRefOp(JavaLanguageParser.RefOpContext ctx) {
1329        final DetailAstImpl bop = create(ctx.bop);
1330        final DetailAstImpl leftChild = visit(ctx.expr());
1331        final DetailAstImpl rightChild = create(TokenTypes.IDENT, ctx.stop);
1332        bop.addChild(leftChild);
1333        bop.addChild(rightChild);
1334        return bop;
1335    }
1336
1337    @Override
1338    public DetailAstImpl visitSuperExp(JavaLanguageParser.SuperExpContext ctx) {
1339        final DetailAstImpl bop = create(ctx.bop);
1340        bop.addChild(visit(ctx.expr()));
1341        bop.addChild(create(ctx.LITERAL_SUPER()));
1342        DetailAstImpl superSuffixParent = visit(ctx.superSuffix());
1343
1344        if (superSuffixParent == null) {
1345            superSuffixParent = bop;
1346        }
1347        else {
1348            DetailAstImpl firstChild = superSuffixParent;
1349            while (firstChild.getFirstChild() != null) {
1350                firstChild = firstChild.getFirstChild();
1351            }
1352            firstChild.addPreviousSibling(bop);
1353        }
1354
1355        return superSuffixParent;
1356    }
1357
1358    @Override
1359    public DetailAstImpl visitInstanceOfExp(JavaLanguageParser.InstanceOfExpContext ctx) {
1360        final DetailAstImpl literalInstanceOf = create(ctx.LITERAL_INSTANCEOF());
1361        literalInstanceOf.addChild(visit(ctx.expr()));
1362        final ParseTree patternOrType = ctx.getChild(2);
1363
1364        final DetailAstImpl patternDef;
1365        if (patternOrType instanceof JavaLanguageParser.ParenPatternContext) {
1366            // Parenthesized pattern has a `PATTERN_DEF` parent
1367            patternDef = createImaginary(TokenTypes.PATTERN_DEF);
1368            patternDef.addChild(visit(patternOrType));
1369        }
1370        else {
1371            patternDef = visit(patternOrType);
1372        }
1373        literalInstanceOf.addChild(patternDef);
1374        return literalInstanceOf;
1375    }
1376
1377    @Override
1378    public DetailAstImpl visitBitShift(JavaLanguageParser.BitShiftContext ctx) {
1379        final DetailAstImpl shiftOperation;
1380
1381        // We determine the type of shift operation in the parser, instead of the
1382        // lexer as in older grammars. This makes it easier to parse type parameters
1383        // and less than/ greater than operators in general.
1384        if (ctx.LT().size() == LEFT_SHIFT.length()) {
1385            shiftOperation = create(TokenTypes.SL, (Token) ctx.LT(0).getPayload());
1386            shiftOperation.setText(LEFT_SHIFT);
1387        }
1388        else if (ctx.GT().size() == UNSIGNED_RIGHT_SHIFT.length()) {
1389            shiftOperation = create(TokenTypes.BSR, (Token) ctx.GT(0).getPayload());
1390            shiftOperation.setText(UNSIGNED_RIGHT_SHIFT);
1391        }
1392        else {
1393            shiftOperation = create(TokenTypes.SR, (Token) ctx.GT(0).getPayload());
1394            shiftOperation.setText(RIGHT_SHIFT);
1395        }
1396
1397        shiftOperation.addChild(visit(ctx.expr(0)));
1398        shiftOperation.addChild(visit(ctx.expr(1)));
1399        return shiftOperation;
1400    }
1401
1402    @Override
1403    public DetailAstImpl visitNewExp(JavaLanguageParser.NewExpContext ctx) {
1404        final DetailAstImpl newExp = create(ctx.LITERAL_NEW());
1405        // child [0] is LITERAL_NEW
1406        processChildren(newExp, ctx.children.subList(1, ctx.children.size()));
1407        return newExp;
1408    }
1409
1410    @Override
1411    public DetailAstImpl visitPrefix(JavaLanguageParser.PrefixContext ctx) {
1412        final int tokenType;
1413        switch (ctx.prefix.getType()) {
1414            case JavaLanguageLexer.PLUS:
1415                tokenType = TokenTypes.UNARY_PLUS;
1416                break;
1417            case JavaLanguageLexer.MINUS:
1418                tokenType = TokenTypes.UNARY_MINUS;
1419                break;
1420            default:
1421                tokenType = ctx.prefix.getType();
1422        }
1423        final DetailAstImpl prefix = create(tokenType, ctx.prefix);
1424        prefix.addChild(visit(ctx.expr()));
1425        return prefix;
1426    }
1427
1428    @Override
1429    public DetailAstImpl visitCastExp(JavaLanguageParser.CastExpContext ctx) {
1430        final DetailAstImpl cast = create(TokenTypes.TYPECAST, (Token) ctx.LPAREN().getPayload());
1431        // child [0] is LPAREN
1432        processChildren(cast, ctx.children.subList(1, ctx.children.size()));
1433        return cast;
1434    }
1435
1436    @Override
1437    public DetailAstImpl visitIndexOp(JavaLanguageParser.IndexOpContext ctx) {
1438        // LBRACK -> INDEX_OP is root of this AST
1439        final DetailAstImpl indexOp = create(TokenTypes.INDEX_OP,
1440                (Token) ctx.LBRACK().getPayload());
1441
1442        // add expression(IDENT) on LHS
1443        indexOp.addChild(visit(ctx.expr(0)));
1444
1445        // create imaginary node for expression on RHS
1446        final DetailAstImpl expr = visit(ctx.expr(1));
1447        final DetailAstImpl imaginaryExpr = createImaginary(TokenTypes.EXPR);
1448        imaginaryExpr.addChild(expr);
1449        indexOp.addChild(imaginaryExpr);
1450
1451        // complete AST by adding RBRACK
1452        indexOp.addChild(create(ctx.RBRACK()));
1453        return indexOp;
1454    }
1455
1456    @Override
1457    public DetailAstImpl visitInvOp(JavaLanguageParser.InvOpContext ctx) {
1458        final DetailAstPair currentAst = new DetailAstPair();
1459
1460        final DetailAstImpl returnAst = visit(ctx.expr());
1461        DetailAstPair.addAstChild(currentAst, returnAst);
1462        DetailAstPair.makeAstRoot(currentAst, create(ctx.bop));
1463
1464        DetailAstPair.addAstChild(currentAst,
1465                 visit(ctx.nonWildcardTypeArguments()));
1466        DetailAstPair.addAstChild(currentAst, visit(ctx.id()));
1467        final DetailAstImpl lparen = create(TokenTypes.METHOD_CALL,
1468                (Token) ctx.LPAREN().getPayload());
1469        DetailAstPair.makeAstRoot(currentAst, lparen);
1470
1471        // We always add an 'ELIST' node
1472        final DetailAstImpl expressionList = Optional.ofNullable(visit(ctx.expressionList()))
1473                .orElseGet(() -> createImaginary(TokenTypes.ELIST));
1474
1475        DetailAstPair.addAstChild(currentAst, expressionList);
1476        DetailAstPair.addAstChild(currentAst, create(ctx.RPAREN()));
1477
1478        return currentAst.root;
1479    }
1480
1481    @Override
1482    public DetailAstImpl visitInitExp(JavaLanguageParser.InitExpContext ctx) {
1483        final DetailAstImpl dot = create(ctx.bop);
1484        dot.addChild(visit(ctx.expr()));
1485        final DetailAstImpl literalNew = create(ctx.LITERAL_NEW());
1486        literalNew.addChild(visit(ctx.nonWildcardTypeArguments()));
1487        literalNew.addChild(visit(ctx.innerCreator()));
1488        dot.addChild(literalNew);
1489        return dot;
1490    }
1491
1492    @Override
1493    public DetailAstImpl visitSimpleMethodCall(JavaLanguageParser.SimpleMethodCallContext ctx) {
1494        final DetailAstImpl methodCall = create(TokenTypes.METHOD_CALL,
1495                (Token) ctx.LPAREN().getPayload());
1496        methodCall.addChild(visit(ctx.id()));
1497        // We always add an 'ELIST' node
1498        final DetailAstImpl expressionList = Optional.ofNullable(visit(ctx.expressionList()))
1499                .orElseGet(() -> createImaginary(TokenTypes.ELIST));
1500
1501        methodCall.addChild(expressionList);
1502        methodCall.addChild(create((Token) ctx.RPAREN().getPayload()));
1503        return methodCall;
1504    }
1505
1506    @Override
1507    public DetailAstImpl visitLambdaExp(JavaLanguageParser.LambdaExpContext ctx) {
1508        final DetailAstImpl lambda = create(ctx.LAMBDA());
1509        lambda.addChild(visit(ctx.lambdaParameters()));
1510
1511        final JavaLanguageParser.BlockContext blockContext = ctx.block();
1512        final DetailAstImpl rightHandLambdaChild;
1513        if (blockContext != null) {
1514            rightHandLambdaChild = visit(blockContext);
1515        }
1516        else {
1517            // Lambda expression child is built the same way that we build
1518            // the initial expression node in visitExpression, i.e. with
1519            // an imaginary EXPR node. This results in nested EXPR nodes
1520            // in the AST.
1521            rightHandLambdaChild = buildExpressionNode(ctx.expr());
1522        }
1523        lambda.addChild(rightHandLambdaChild);
1524        return lambda;
1525    }
1526
1527    @Override
1528    public DetailAstImpl visitThisExp(JavaLanguageParser.ThisExpContext ctx) {
1529        final DetailAstImpl bop = create(ctx.bop);
1530        bop.addChild(visit(ctx.expr()));
1531        bop.addChild(create(ctx.LITERAL_THIS()));
1532        return bop;
1533    }
1534
1535    @Override
1536    public DetailAstImpl visitPrimaryExp(JavaLanguageParser.PrimaryExpContext ctx) {
1537        return flattenedTree(ctx);
1538    }
1539
1540    @Override
1541    public DetailAstImpl visitPostfix(JavaLanguageParser.PostfixContext ctx) {
1542        final DetailAstImpl postfix;
1543        if (ctx.postfix.getType() == JavaLanguageLexer.INC) {
1544            postfix = create(TokenTypes.POST_INC, ctx.postfix);
1545        }
1546        else {
1547            postfix = create(TokenTypes.POST_DEC, ctx.postfix);
1548        }
1549        postfix.addChild(visit(ctx.expr()));
1550        return postfix;
1551    }
1552
1553    @Override
1554    public DetailAstImpl visitMethodRef(JavaLanguageParser.MethodRefContext ctx) {
1555        final DetailAstImpl doubleColon = create(TokenTypes.METHOD_REF,
1556                (Token) ctx.DOUBLE_COLON().getPayload());
1557        final List<ParseTree> children = ctx.children.stream()
1558                .filter(child -> !child.equals(ctx.DOUBLE_COLON()))
1559                .collect(Collectors.toUnmodifiableList());
1560        processChildren(doubleColon, children);
1561        return doubleColon;
1562    }
1563
1564    @Override
1565    public DetailAstImpl visitTernaryOp(JavaLanguageParser.TernaryOpContext ctx) {
1566        final DetailAstImpl root = create(ctx.QUESTION());
1567        processChildren(root, ctx.children.stream()
1568                .filter(child -> !child.equals(ctx.QUESTION()))
1569                .collect(Collectors.toUnmodifiableList()));
1570        return root;
1571    }
1572
1573    @Override
1574    public DetailAstImpl visitBinOp(JavaLanguageParser.BinOpContext ctx) {
1575        final DetailAstImpl bop = create(ctx.bop);
1576
1577        // To improve performance, we iterate through binary operations
1578        // since they are frequently deeply nested.
1579        final List<JavaLanguageParser.BinOpContext> binOpList = new ArrayList<>();
1580        ParseTree firstExpression = ctx.expr(0);
1581        while (firstExpression instanceof JavaLanguageParser.BinOpContext) {
1582            // Get all nested binOps
1583            binOpList.add((JavaLanguageParser.BinOpContext) firstExpression);
1584            firstExpression = ((JavaLanguageParser.BinOpContext) firstExpression).expr(0);
1585        }
1586
1587        if (binOpList.isEmpty()) {
1588            final DetailAstImpl leftChild = visit(ctx.children.get(0));
1589            bop.addChild(leftChild);
1590        }
1591        else {
1592            // Map all descendants to individual AST's since we can parallelize this
1593            // operation
1594            final Queue<DetailAstImpl> descendantList = binOpList.parallelStream()
1595                    .map(this::getInnerBopAst)
1596                    .collect(Collectors.toCollection(ConcurrentLinkedQueue::new));
1597
1598            bop.addChild(descendantList.poll());
1599            DetailAstImpl pointer = bop.getFirstChild();
1600            // Build tree
1601            for (DetailAstImpl descendant : descendantList) {
1602                pointer.getFirstChild().addPreviousSibling(descendant);
1603                pointer = descendant;
1604            }
1605        }
1606
1607        bop.addChild(visit(ctx.children.get(2)));
1608        return bop;
1609    }
1610
1611    /**
1612     * Builds the binary operation (binOp) AST.
1613     *
1614     * @param descendant the BinOpContext to build AST from
1615     * @return binOp AST
1616     */
1617    private DetailAstImpl getInnerBopAst(JavaLanguageParser.BinOpContext descendant) {
1618        final DetailAstImpl innerBop = create(descendant.bop);
1619        final JavaLanguageParser.ExprContext expr = descendant.expr(0);
1620        if (!(expr instanceof JavaLanguageParser.BinOpContext)) {
1621            innerBop.addChild(visit(expr));
1622        }
1623        innerBop.addChild(visit(descendant.expr(1)));
1624        return innerBop;
1625    }
1626
1627    @Override
1628    public DetailAstImpl visitMethodCall(JavaLanguageParser.MethodCallContext ctx) {
1629        final DetailAstImpl methodCall = create(TokenTypes.METHOD_CALL,
1630                (Token) ctx.LPAREN().getPayload());
1631        // We always add an 'ELIST' node
1632        final DetailAstImpl expressionList = Optional.ofNullable(visit(ctx.expressionList()))
1633                .orElseGet(() -> createImaginary(TokenTypes.ELIST));
1634
1635        final DetailAstImpl dot = create(ctx.DOT());
1636        dot.addChild(visit(ctx.expr()));
1637        dot.addChild(visit(ctx.id()));
1638        methodCall.addChild(dot);
1639        methodCall.addChild(expressionList);
1640        methodCall.addChild(create((Token) ctx.RPAREN().getPayload()));
1641        return methodCall;
1642    }
1643
1644    @Override
1645    public DetailAstImpl visitTypeCastParameters(
1646            JavaLanguageParser.TypeCastParametersContext ctx) {
1647        final DetailAstImpl typeType = visit(ctx.typeType(0));
1648        for (int i = 0; i < ctx.BAND().size(); i++) {
1649            addLastSibling(typeType, create(TokenTypes.TYPE_EXTENSION_AND,
1650                                (Token) ctx.BAND(i).getPayload()));
1651            addLastSibling(typeType, visit(ctx.typeType(i + 1)));
1652        }
1653        return typeType;
1654    }
1655
1656    @Override
1657    public DetailAstImpl visitSingleLambdaParam(JavaLanguageParser.SingleLambdaParamContext ctx) {
1658        return flattenedTree(ctx);
1659    }
1660
1661    @Override
1662    public DetailAstImpl visitFormalLambdaParam(JavaLanguageParser.FormalLambdaParamContext ctx) {
1663        final DetailAstImpl lparen = create(ctx.LPAREN());
1664
1665        // We add an 'PARAMETERS' node here whether it exists or not
1666        final DetailAstImpl parameters = Optional.ofNullable(visit(ctx.formalParameterList()))
1667                .orElseGet(() -> createImaginary(TokenTypes.PARAMETERS));
1668        addLastSibling(lparen, parameters);
1669        addLastSibling(lparen, create(ctx.RPAREN()));
1670        return lparen;
1671    }
1672
1673    @Override
1674    public DetailAstImpl visitMultiLambdaParam(JavaLanguageParser.MultiLambdaParamContext ctx) {
1675        final DetailAstImpl lparen = create(ctx.LPAREN());
1676        addLastSibling(lparen, visit(ctx.multiLambdaParams()));
1677        addLastSibling(lparen, create(ctx.RPAREN()));
1678        return lparen;
1679    }
1680
1681    @Override
1682    public DetailAstImpl visitMultiLambdaParams(JavaLanguageParser.MultiLambdaParamsContext ctx) {
1683        final DetailAstImpl parameters = createImaginary(TokenTypes.PARAMETERS);
1684        parameters.addChild(createLambdaParameter(ctx.id(0)));
1685
1686        for (int i = 0; i < ctx.COMMA().size(); i++) {
1687            parameters.addChild(create(ctx.COMMA(i)));
1688            parameters.addChild(createLambdaParameter(ctx.id(i + 1)));
1689        }
1690        return parameters;
1691    }
1692
1693    /**
1694     * Creates a 'PARAMETER_DEF' node for a lambda expression, with
1695     * imaginary modifier and type nodes.
1696     *
1697     * @param ctx the IdContext to create imaginary nodes for
1698     * @return DetailAstImpl of lambda parameter
1699     */
1700    private DetailAstImpl createLambdaParameter(JavaLanguageParser.IdContext ctx) {
1701        final DetailAstImpl ident = visitId(ctx);
1702        final DetailAstImpl parameter = createImaginary(TokenTypes.PARAMETER_DEF);
1703        final DetailAstImpl modifiers = createImaginary(TokenTypes.MODIFIERS);
1704        final DetailAstImpl type = createImaginary(TokenTypes.TYPE);
1705        parameter.addChild(modifiers);
1706        parameter.addChild(type);
1707        parameter.addChild(ident);
1708        return parameter;
1709    }
1710
1711    @Override
1712    public DetailAstImpl visitParenPrimary(JavaLanguageParser.ParenPrimaryContext ctx) {
1713        return flattenedTree(ctx);
1714    }
1715
1716    @Override
1717    public DetailAstImpl visitTokenPrimary(JavaLanguageParser.TokenPrimaryContext ctx) {
1718        return flattenedTree(ctx);
1719    }
1720
1721    @Override
1722    public DetailAstImpl visitClassRefPrimary(JavaLanguageParser.ClassRefPrimaryContext ctx) {
1723        final DetailAstImpl dot = create(ctx.DOT());
1724        final DetailAstImpl primaryTypeNoArray = visit(ctx.type);
1725        dot.addChild(primaryTypeNoArray);
1726        if (TokenUtil.isOfType(primaryTypeNoArray, TokenTypes.DOT)) {
1727            // We append '[]' to the qualified name 'TYPE' `ast
1728            ctx.arrayDeclarator()
1729                    .forEach(child -> primaryTypeNoArray.addChild(visit(child)));
1730        }
1731        else {
1732            ctx.arrayDeclarator()
1733                    .forEach(child -> addLastSibling(primaryTypeNoArray, visit(child)));
1734        }
1735        dot.addChild(create(ctx.LITERAL_CLASS()));
1736        return dot;
1737    }
1738
1739    @Override
1740    public DetailAstImpl visitPrimitivePrimary(JavaLanguageParser.PrimitivePrimaryContext ctx) {
1741        final DetailAstImpl dot = create(ctx.DOT());
1742        final DetailAstImpl primaryTypeNoArray = visit(ctx.type);
1743        dot.addChild(primaryTypeNoArray);
1744        ctx.arrayDeclarator().forEach(child -> dot.addChild(visit(child)));
1745        dot.addChild(create(ctx.LITERAL_CLASS()));
1746        return dot;
1747    }
1748
1749    @Override
1750    public DetailAstImpl visitCreator(JavaLanguageParser.CreatorContext ctx) {
1751        return flattenedTree(ctx);
1752    }
1753
1754    @Override
1755    public DetailAstImpl visitCreatedNameObject(JavaLanguageParser.CreatedNameObjectContext ctx) {
1756        final DetailAstPair currentAST = new DetailAstPair();
1757        DetailAstPair.addAstChild(currentAST, visit(ctx.annotations()));
1758        DetailAstPair.addAstChild(currentAST, visit(ctx.id()));
1759        DetailAstPair.addAstChild(currentAST, visit(ctx.typeArgumentsOrDiamond()));
1760
1761        // This is how we build the type arguments/ qualified name tree
1762        for (ParserRuleContext extendedContext : ctx.extended) {
1763            final DetailAstImpl dot = create(extendedContext.start);
1764            DetailAstPair.makeAstRoot(currentAST, dot);
1765            final List<ParseTree> childList = extendedContext
1766                    .children.subList(1, extendedContext.children.size());
1767            processChildren(dot, childList);
1768        }
1769
1770        return currentAST.root;
1771    }
1772
1773    @Override
1774    public DetailAstImpl visitCreatedNamePrimitive(
1775            JavaLanguageParser.CreatedNamePrimitiveContext ctx) {
1776        return flattenedTree(ctx);
1777    }
1778
1779    @Override
1780    public DetailAstImpl visitInnerCreator(JavaLanguageParser.InnerCreatorContext ctx) {
1781        return flattenedTree(ctx);
1782    }
1783
1784    @Override
1785    public DetailAstImpl visitArrayCreatorRest(JavaLanguageParser.ArrayCreatorRestContext ctx) {
1786        final DetailAstImpl arrayDeclarator = create(TokenTypes.ARRAY_DECLARATOR,
1787                (Token) ctx.LBRACK().getPayload());
1788        final JavaLanguageParser.ExpressionContext expression = ctx.expression();
1789        final TerminalNode rbrack = ctx.RBRACK();
1790        // child[0] is LBRACK
1791        for (int i = 1; i < ctx.children.size(); i++) {
1792            if (ctx.children.get(i) == rbrack) {
1793                arrayDeclarator.addChild(create(rbrack));
1794            }
1795            else if (ctx.children.get(i) == expression) {
1796                // Handle '[8]', etc.
1797                arrayDeclarator.addChild(visit(expression));
1798            }
1799            else {
1800                addLastSibling(arrayDeclarator, visit(ctx.children.get(i)));
1801            }
1802        }
1803        return arrayDeclarator;
1804    }
1805
1806    @Override
1807    public DetailAstImpl visitBracketsWithExp(JavaLanguageParser.BracketsWithExpContext ctx) {
1808        final DetailAstImpl dummyRoot = new DetailAstImpl();
1809        dummyRoot.addChild(visit(ctx.annotations()));
1810        final DetailAstImpl arrayDeclarator =
1811                create(TokenTypes.ARRAY_DECLARATOR, (Token) ctx.LBRACK().getPayload());
1812        arrayDeclarator.addChild(visit(ctx.expression()));
1813        arrayDeclarator.addChild(create(ctx.stop));
1814        dummyRoot.addChild(arrayDeclarator);
1815        return dummyRoot.getFirstChild();
1816    }
1817
1818    @Override
1819    public DetailAstImpl visitClassCreatorRest(JavaLanguageParser.ClassCreatorRestContext ctx) {
1820        return flattenedTree(ctx);
1821    }
1822
1823    @Override
1824    public DetailAstImpl visitDiamond(JavaLanguageParser.DiamondContext ctx) {
1825        final DetailAstImpl typeArguments =
1826                createImaginary(TokenTypes.TYPE_ARGUMENTS);
1827        typeArguments.addChild(create(TokenTypes.GENERIC_START,
1828                (Token) ctx.LT().getPayload()));
1829        typeArguments.addChild(create(TokenTypes.GENERIC_END,
1830                (Token) ctx.GT().getPayload()));
1831        return typeArguments;
1832    }
1833
1834    @Override
1835    public DetailAstImpl visitTypeArgs(JavaLanguageParser.TypeArgsContext ctx) {
1836        return flattenedTree(ctx);
1837    }
1838
1839    @Override
1840    public DetailAstImpl visitNonWildcardDiamond(
1841            JavaLanguageParser.NonWildcardDiamondContext ctx) {
1842        final DetailAstImpl typeArguments =
1843                createImaginary(TokenTypes.TYPE_ARGUMENTS);
1844        typeArguments.addChild(create(TokenTypes.GENERIC_START,
1845                (Token) ctx.LT().getPayload()));
1846        typeArguments.addChild(create(TokenTypes.GENERIC_END,
1847                (Token) ctx.GT().getPayload()));
1848        return typeArguments;
1849    }
1850
1851    @Override
1852    public DetailAstImpl visitNonWildcardTypeArguments(
1853            JavaLanguageParser.NonWildcardTypeArgumentsContext ctx) {
1854        final DetailAstImpl typeArguments = createImaginary(TokenTypes.TYPE_ARGUMENTS);
1855        typeArguments.addChild(create(TokenTypes.GENERIC_START, (Token) ctx.LT().getPayload()));
1856        typeArguments.addChild(visit(ctx.typeArgumentsTypeList()));
1857        typeArguments.addChild(create(TokenTypes.GENERIC_END, (Token) ctx.GT().getPayload()));
1858        return typeArguments;
1859    }
1860
1861    @Override
1862    public DetailAstImpl visitTypeArgumentsTypeList(
1863            JavaLanguageParser.TypeArgumentsTypeListContext ctx) {
1864        final DetailAstImpl firstIdent = visit(ctx.typeType(0));
1865        final DetailAstImpl firstTypeArgument = createImaginary(TokenTypes.TYPE_ARGUMENT);
1866        firstTypeArgument.addChild(firstIdent);
1867
1868        for (int i = 0; i < ctx.COMMA().size(); i++) {
1869            addLastSibling(firstTypeArgument, create(ctx.COMMA(i)));
1870            final DetailAstImpl ident = visit(ctx.typeType(i + 1));
1871            final DetailAstImpl typeArgument = createImaginary(TokenTypes.TYPE_ARGUMENT);
1872            typeArgument.addChild(ident);
1873            addLastSibling(firstTypeArgument, typeArgument);
1874        }
1875        return firstTypeArgument;
1876    }
1877
1878    @Override
1879    public DetailAstImpl visitTypeList(JavaLanguageParser.TypeListContext ctx) {
1880        return flattenedTree(ctx);
1881    }
1882
1883    @Override
1884    public DetailAstImpl visitTypeType(JavaLanguageParser.TypeTypeContext ctx) {
1885        final DetailAstImpl type = createImaginary(TokenTypes.TYPE);
1886        processChildren(type, ctx.children);
1887
1888        final DetailAstImpl returnTree;
1889        if (ctx.createImaginaryNode) {
1890            returnTree = type;
1891        }
1892        else {
1893            returnTree = type.getFirstChild();
1894        }
1895        return returnTree;
1896    }
1897
1898    @Override
1899    public DetailAstImpl visitArrayDeclarator(JavaLanguageParser.ArrayDeclaratorContext ctx) {
1900        final DetailAstImpl arrayDeclarator = create(TokenTypes.ARRAY_DECLARATOR,
1901                (Token) ctx.LBRACK().getPayload());
1902        arrayDeclarator.addChild(create(ctx.RBRACK()));
1903
1904        final DetailAstImpl returnTree;
1905        final DetailAstImpl annotations = visit(ctx.anno);
1906        if (annotations == null) {
1907            returnTree = arrayDeclarator;
1908        }
1909        else {
1910            returnTree = annotations;
1911            addLastSibling(returnTree, arrayDeclarator);
1912        }
1913        return returnTree;
1914    }
1915
1916    @Override
1917    public DetailAstImpl visitPrimitiveType(JavaLanguageParser.PrimitiveTypeContext ctx) {
1918        return create(ctx.start);
1919    }
1920
1921    @Override
1922    public DetailAstImpl visitTypeArguments(JavaLanguageParser.TypeArgumentsContext ctx) {
1923        final DetailAstImpl typeArguments = createImaginary(TokenTypes.TYPE_ARGUMENTS);
1924        typeArguments.addChild(create(TokenTypes.GENERIC_START, (Token) ctx.LT().getPayload()));
1925        // Exclude '<' and '>'
1926        processChildren(typeArguments, ctx.children.subList(1, ctx.children.size() - 1));
1927        typeArguments.addChild(create(TokenTypes.GENERIC_END, (Token) ctx.GT().getPayload()));
1928        return typeArguments;
1929    }
1930
1931    @Override
1932    public DetailAstImpl visitSuperSuffixDot(JavaLanguageParser.SuperSuffixDotContext ctx) {
1933        final DetailAstImpl root;
1934        if (ctx.LPAREN() == null) {
1935            root = create(ctx.DOT());
1936            root.addChild(visit(ctx.id()));
1937        }
1938        else {
1939            root = create(TokenTypes.METHOD_CALL, (Token) ctx.LPAREN().getPayload());
1940
1941            final DetailAstImpl dot = create(ctx.DOT());
1942            dot.addChild(visit(ctx.id()));
1943            root.addChild(dot);
1944
1945            final DetailAstImpl expressionList = Optional.ofNullable(visit(ctx.expressionList()))
1946                    .orElseGet(() -> createImaginary(TokenTypes.ELIST));
1947            root.addChild(expressionList);
1948
1949            root.addChild(create(ctx.RPAREN()));
1950        }
1951
1952        return root;
1953    }
1954
1955    @Override
1956    public DetailAstImpl visitArguments(JavaLanguageParser.ArgumentsContext ctx) {
1957        final DetailAstImpl lparen = create(ctx.LPAREN());
1958
1959        // We always add an 'ELIST' node
1960        final DetailAstImpl expressionList = Optional.ofNullable(visit(ctx.expressionList()))
1961                .orElseGet(() -> createImaginary(TokenTypes.ELIST));
1962        addLastSibling(lparen, expressionList);
1963        addLastSibling(lparen, create(ctx.RPAREN()));
1964        return lparen;
1965    }
1966
1967    @Override
1968    public DetailAstImpl visitPattern(JavaLanguageParser.PatternContext ctx) {
1969        final JavaLanguageParser.InnerPatternContext innerPattern = ctx.innerPattern();
1970        final ParserRuleContext primaryPattern = innerPattern.primaryPattern();
1971        final ParserRuleContext recordPattern = innerPattern.recordPattern();
1972        final boolean isSimpleTypePattern = primaryPattern != null
1973                && primaryPattern.getChild(0) instanceof JavaLanguageParser.TypePatternContext;
1974
1975        final DetailAstImpl pattern;
1976
1977        if (recordPattern != null) {
1978            pattern = visit(recordPattern);
1979        }
1980        else if (isSimpleTypePattern) {
1981            // For simple type pattern like 'Integer i`, we do not add `PATTERN_DEF` parent
1982            pattern = visit(primaryPattern);
1983        }
1984        else {
1985            pattern = createImaginary(TokenTypes.PATTERN_DEF);
1986            pattern.addChild(visit(ctx.getChild(0)));
1987        }
1988        return pattern;
1989    }
1990
1991    @Override
1992    public DetailAstImpl visitInnerPattern(JavaLanguageParser.InnerPatternContext ctx) {
1993        return flattenedTree(ctx);
1994    }
1995
1996    @Override
1997    public DetailAstImpl visitGuardedPattern(JavaLanguageParser.GuardedPatternContext ctx) {
1998        final DetailAstImpl guardAstNode = flattenedTree(ctx.guard());
1999        guardAstNode.addChild(visit(ctx.primaryPattern()));
2000        guardAstNode.addChild(visit(ctx.expression()));
2001        return guardAstNode;
2002    }
2003
2004    @Override
2005    public DetailAstImpl visitParenPattern(JavaLanguageParser.ParenPatternContext ctx) {
2006        final DetailAstImpl lparen = create(ctx.LPAREN());
2007        final ParseTree innerPattern = ctx.getChild(1);
2008        lparen.addChild(visit(innerPattern));
2009        lparen.addChild(create(ctx.RPAREN()));
2010        return lparen;
2011    }
2012
2013    @Override
2014    public DetailAstImpl visitRecordPatternDef(JavaLanguageParser.RecordPatternDefContext ctx) {
2015        return flattenedTree(ctx);
2016    }
2017
2018    @Override
2019    public DetailAstImpl visitTypePatternDef(
2020            JavaLanguageParser.TypePatternDefContext ctx) {
2021        final DetailAstImpl type = visit(ctx.type);
2022        final DetailAstImpl patternVariableDef = createImaginary(TokenTypes.PATTERN_VARIABLE_DEF);
2023        patternVariableDef.addChild(createModifiers(ctx.mods));
2024        patternVariableDef.addChild(type);
2025        patternVariableDef.addChild(visit(ctx.id()));
2026        return patternVariableDef;
2027    }
2028
2029    @Override
2030    public DetailAstImpl visitUnnamedPatternDef(JavaLanguageParser.UnnamedPatternDefContext ctx) {
2031        return create(TokenTypes.UNNAMED_PATTERN_DEF, ctx.start);
2032    }
2033
2034    @Override
2035    public DetailAstImpl visitRecordPattern(JavaLanguageParser.RecordPatternContext ctx) {
2036        final DetailAstImpl recordPattern = createImaginary(TokenTypes.RECORD_PATTERN_DEF);
2037        recordPattern.addChild(createModifiers(ctx.mods));
2038        processChildren(recordPattern,
2039                ctx.children.subList(ctx.mods.size(), ctx.children.size()));
2040        return recordPattern;
2041    }
2042
2043    @Override
2044    public DetailAstImpl visitRecordComponentPatternList(
2045            JavaLanguageParser.RecordComponentPatternListContext ctx) {
2046        final DetailAstImpl recordComponents =
2047                createImaginary(TokenTypes.RECORD_PATTERN_COMPONENTS);
2048        processChildren(recordComponents, ctx.children);
2049        return recordComponents;
2050    }
2051
2052    @Override
2053    public DetailAstImpl visitPermittedSubclassesAndInterfaces(
2054            JavaLanguageParser.PermittedSubclassesAndInterfacesContext ctx) {
2055        final DetailAstImpl literalPermits =
2056                create(TokenTypes.PERMITS_CLAUSE, (Token) ctx.LITERAL_PERMITS().getPayload());
2057        // 'LITERAL_PERMITS' is child[0]
2058        processChildren(literalPermits, ctx.children.subList(1, ctx.children.size()));
2059        return literalPermits;
2060    }
2061
2062    @Override
2063    public DetailAstImpl visitId(JavaLanguageParser.IdContext ctx) {
2064        return create(TokenTypes.IDENT, ctx.start);
2065    }
2066
2067    /**
2068     * Builds the AST for a particular node, then returns a "flattened" tree
2069     * of siblings. This method should be used in rule contexts such as
2070     * {@code variableDeclarators}, where we have both terminals and non-terminals.
2071     *
2072     * @param ctx the ParserRuleContext to base tree on
2073     * @return flattened DetailAstImpl
2074     */
2075    private DetailAstImpl flattenedTree(ParserRuleContext ctx) {
2076        final DetailAstImpl dummyNode = new DetailAstImpl();
2077        processChildren(dummyNode, ctx.children);
2078        return dummyNode.getFirstChild();
2079    }
2080
2081    /**
2082     * Adds all the children from the given ParseTree or JavaParserContext
2083     * list to the parent DetailAstImpl.
2084     *
2085     * @param parent the DetailAstImpl to add children to
2086     * @param children the list of children to add
2087     */
2088    private void processChildren(DetailAstImpl parent, List<? extends ParseTree> children) {
2089        children.forEach(child -> {
2090            if (child instanceof TerminalNode) {
2091                // Child is a token, create a new DetailAstImpl and add it to parent
2092                parent.addChild(create((TerminalNode) child));
2093            }
2094            else {
2095                // Child is another rule context; visit it, create token, and add to parent
2096                parent.addChild(visit(child));
2097            }
2098        });
2099    }
2100
2101    /**
2102     * Create a DetailAstImpl from a given token and token type. This method
2103     * should be used for imaginary nodes only, i.e. 'OBJBLOCK -&gt; OBJBLOCK',
2104     * where the text on the RHS matches the text on the LHS.
2105     *
2106     * @param tokenType the token type of this DetailAstImpl
2107     * @return new DetailAstImpl of given type
2108     */
2109    private static DetailAstImpl createImaginary(int tokenType) {
2110        final DetailAstImpl detailAst = new DetailAstImpl();
2111        detailAst.setType(tokenType);
2112        detailAst.setText(TokenUtil.getTokenName(tokenType));
2113        return detailAst;
2114    }
2115
2116    /**
2117     * Create a DetailAstImpl from a given token and token type. This method
2118     * should be used for literal nodes only, i.e. 'PACKAGE_DEF -&gt; package'.
2119     *
2120     * @param tokenType the token type of this DetailAstImpl
2121     * @param startToken the first token that appears in this DetailAstImpl.
2122     * @return new DetailAstImpl of given type
2123     */
2124    private DetailAstImpl create(int tokenType, Token startToken) {
2125        final DetailAstImpl ast = create(startToken);
2126        ast.setType(tokenType);
2127        return ast;
2128    }
2129
2130    /**
2131     * Create a DetailAstImpl from a given token. This method should be
2132     * used for terminal nodes, i.e. {@code LCURLY}, when we are building
2133     * an AST for a specific token, regardless of position.
2134     *
2135     * @param token the token to build the DetailAstImpl from
2136     * @return new DetailAstImpl of given type
2137     */
2138    private DetailAstImpl create(Token token) {
2139        final int tokenIndex = token.getTokenIndex();
2140        final List<Token> tokensToLeft =
2141                tokens.getHiddenTokensToLeft(tokenIndex, JavaLanguageLexer.COMMENTS);
2142        final List<Token> tokensToRight =
2143                tokens.getHiddenTokensToRight(tokenIndex, JavaLanguageLexer.COMMENTS);
2144
2145        final DetailAstImpl detailAst = new DetailAstImpl();
2146        detailAst.initialize(token);
2147        if (tokensToLeft != null) {
2148            detailAst.setHiddenBefore(tokensToLeft);
2149        }
2150        if (tokensToRight != null) {
2151            detailAst.setHiddenAfter(tokensToRight);
2152        }
2153        return detailAst;
2154    }
2155
2156    /**
2157     * Create a DetailAstImpl from a given TerminalNode. This method should be
2158     * used for terminal nodes, i.e. {@code @}.
2159     *
2160     * @param node the TerminalNode to build the DetailAstImpl from
2161     * @return new DetailAstImpl of given type
2162     */
2163    private DetailAstImpl create(TerminalNode node) {
2164        return create((Token) node.getPayload());
2165    }
2166
2167    /**
2168     * Creates a type declaration DetailAstImpl from a given rule context.
2169     *
2170     * @param ctx ParserRuleContext we are in
2171     * @param type the type declaration to create
2172     * @param modifierList respective modifiers
2173     * @return type declaration DetailAstImpl
2174     */
2175    private DetailAstImpl createTypeDeclaration(ParserRuleContext ctx, int type,
2176                                                List<? extends ParseTree> modifierList) {
2177        final DetailAstImpl typeDeclaration = createImaginary(type);
2178        typeDeclaration.addChild(createModifiers(modifierList));
2179        processChildren(typeDeclaration, ctx.children);
2180        return typeDeclaration;
2181    }
2182
2183    /**
2184     * Builds the modifiers AST.
2185     *
2186     * @param modifierList the list of modifier contexts
2187     * @return "MODIFIERS" ast
2188     */
2189    private DetailAstImpl createModifiers(List<? extends ParseTree> modifierList) {
2190        final DetailAstImpl mods = createImaginary(TokenTypes.MODIFIERS);
2191        processChildren(mods, modifierList);
2192        return mods;
2193    }
2194
2195    /**
2196     * Add new sibling to the end of existing siblings.
2197     *
2198     * @param self DetailAstImpl to add last sibling to
2199     * @param sibling DetailAstImpl sibling to add
2200     */
2201    private static void addLastSibling(DetailAstImpl self, DetailAstImpl sibling) {
2202        DetailAstImpl nextSibling = self;
2203        if (nextSibling != null) {
2204            while (nextSibling.getNextSibling() != null) {
2205                nextSibling = nextSibling.getNextSibling();
2206            }
2207            nextSibling.setNextSibling(sibling);
2208        }
2209    }
2210
2211    @Override
2212    public DetailAstImpl visit(ParseTree tree) {
2213        DetailAstImpl ast = null;
2214        if (tree != null) {
2215            ast = tree.accept(this);
2216        }
2217        return ast;
2218    }
2219
2220    /**
2221     * Builds an expression node. This is used to build the root of an expression with
2222     * an imaginary {@code EXPR} node.
2223     *
2224     * @param exprNode expression to build node for
2225     * @return expression DetailAstImpl node
2226     */
2227    private DetailAstImpl buildExpressionNode(ParseTree exprNode) {
2228        final DetailAstImpl expression = visit(exprNode);
2229
2230        final DetailAstImpl exprRoot;
2231        if (TokenUtil.isOfType(expression, EXPRESSIONS_WITH_NO_EXPR_ROOT)) {
2232            exprRoot = expression;
2233        }
2234        else {
2235            // create imaginary 'EXPR' node as root of expression
2236            exprRoot = createImaginary(TokenTypes.EXPR);
2237            exprRoot.addChild(expression);
2238        }
2239        return exprRoot;
2240    }
2241
2242    /**
2243     * Used to swap and organize DetailAstImpl subtrees.
2244     */
2245    private static final class DetailAstPair {
2246
2247        /** The root DetailAstImpl of this pair. */
2248        private DetailAstImpl root;
2249
2250        /** The child (potentially with siblings) of this pair. */
2251        private DetailAstImpl child;
2252
2253        /**
2254         * Moves child reference to the last child.
2255         */
2256        private void advanceChildToEnd() {
2257            while (child.getNextSibling() != null) {
2258                child = child.getNextSibling();
2259            }
2260        }
2261
2262        /**
2263         * Returns the root node.
2264         *
2265         * @return the root node
2266         */
2267        private DetailAstImpl getRoot() {
2268            return root;
2269        }
2270
2271        /**
2272         * This method is used to replace the {@code ^} (set as root node) ANTLR2
2273         * operator.
2274         *
2275         * @param pair the DetailAstPair to use for swapping nodes
2276         * @param ast the new root
2277         */
2278        private static void makeAstRoot(DetailAstPair pair, DetailAstImpl ast) {
2279            ast.addChild(pair.root);
2280            pair.child = pair.root;
2281            pair.advanceChildToEnd();
2282            pair.root = ast;
2283        }
2284
2285        /**
2286         * Adds a child (or new root) to the given DetailAstPair.
2287         *
2288         * @param pair the DetailAstPair to add child to
2289         * @param ast the child to add
2290         */
2291        private static void addAstChild(DetailAstPair pair, DetailAstImpl ast) {
2292            if (ast != null) {
2293                if (pair.root == null) {
2294                    pair.root = ast;
2295                }
2296                else {
2297                    pair.child.setNextSibling(ast);
2298                }
2299                pair.child = ast;
2300            }
2301        }
2302    }
2303}