/*
 * Copyright (c) 1999, 2016, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.tools.javac.tree;



import com.sun.source.tree.Tree;
import com.sun.source.util.TreePath;
import com.sun.tools.javac.code.*;
import com.sun.tools.javac.comp.AttrContext;
import com.sun.tools.javac.comp.Env;
import com.sun.tools.javac.tree.JCTree.*;
import com.sun.tools.javac.tree.JCTree.JCPolyExpression.*;
import com.sun.tools.javac.util.*;
import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;

import static com.sun.tools.javac.code.Flags.*;
import static com.sun.tools.javac.code.Kinds.Kind.*;
import static com.sun.tools.javac.code.TypeTag.BOT;
import static com.sun.tools.javac.tree.JCTree.Tag.*;
import static com.sun.tools.javac.tree.JCTree.Tag.BLOCK;
import static com.sun.tools.javac.tree.JCTree.Tag.SYNCHRONIZED;

import javax.tools.JavaFileObject;

import static com.sun.tools.javac.tree.JCTree.JCOperatorExpression.OperandPos.LEFT;
import static com.sun.tools.javac.tree.JCTree.JCOperatorExpression.OperandPos.RIGHT;

Utility class containing inspector methods for trees.
 
This is NOT part of any supported API.
 If you write code that depends on this, you do so at your own risk.
 This code and its internal interfaces are subject to change or
 deletion without notice.
/** Utility class containing inspector methods for trees.
 *
 *  <p><b>This is NOT part of any supported API.
 *  If you write code that depends on this, you do so at your own risk.
 *  This code and its internal interfaces are subject to change or
 *  deletion without notice.</b>
 */
public class TreeInfo {

    public static List<JCExpression> args(JCTree t) {
        switch (t.getTag()) {
            case APPLY:
                return ((JCMethodInvocation)t).args;
            case NEWCLASS:
                return ((JCNewClass)t).args;
            default:
                return null;
        }
    }

    
Is tree a constructor declaration?
/** Is tree a constructor declaration?
     */
    public static boolean isConstructor(JCTree tree) {
        if (tree.hasTag(METHODDEF)) {
            Name name = ((JCMethodDecl) tree).name;
            return name == name.table.names.init;
        } else {
            return false;
        }
    }

    public static boolean isReceiverParam(JCTree tree) {
        if (tree.hasTag(VARDEF)) {
            return ((JCVariableDecl)tree).nameexpr != null;
        } else {
            return false;
        }
    }

    
Is there a constructor declaration in the given list of trees?
/** Is there a constructor declaration in the given list of trees?
     */
    public static boolean hasConstructors(List<JCTree> trees) {
        for (List<JCTree> l = trees; l.nonEmpty(); l = l.tail)
            if (isConstructor(l.head)) return true;
        return false;
    }

    public static boolean isMultiCatch(JCCatch catchClause) {
        return catchClause.param.vartype.hasTag(TYPEUNION);
    }

    
Is statement an initializer for a synthetic field?
/** Is statement an initializer for a synthetic field?
     */
    public static boolean isSyntheticInit(JCTree stat) {
        if (stat.hasTag(EXEC)) {
            JCExpressionStatement exec = (JCExpressionStatement)stat;
            if (exec.expr.hasTag(ASSIGN)) {
                JCAssign assign = (JCAssign)exec.expr;
                if (assign.lhs.hasTag(SELECT)) {
                    JCFieldAccess select = (JCFieldAccess)assign.lhs;
                    if (select.sym != null &&
                        (select.sym.flags() & SYNTHETIC) != 0) {
                        Name selected = name(select.selected);
                        if (selected != null && selected == selected.table.names._this)
                            return true;
                    }
                }
            }
        }
        return false;
    }

    
If the expression is a method call, return the method name, null
 otherwise. /** If the expression is a method call, return the method name, null
     *  otherwise. */
    public static Name calledMethodName(JCTree tree) {
        if (tree.hasTag(EXEC)) {
            JCExpressionStatement exec = (JCExpressionStatement)tree;
            if (exec.expr.hasTag(APPLY)) {
                Name mname = TreeInfo.name(((JCMethodInvocation) exec.expr).meth);
                return mname;
            }
        }
        return null;
    }

    
Is this a call to this or super?
/** Is this a call to this or super?
     */
    public static boolean isSelfCall(JCTree tree) {
        Name name = calledMethodName(tree);
        if (name != null) {
            Names names = name.table.names;
            return name==names._this || name==names._super;
        } else {
            return false;
        }
    }

    
Is this a call to super?
/** Is this a call to super?
     */
    public static boolean isSuperCall(JCTree tree) {
        Name name = calledMethodName(tree);
        if (name != null) {
            Names names = name.table.names;
            return name==names._super;
        } else {
            return false;
        }
    }

    
Is this a constructor whose first (non-synthetic) statement is not
 of the form this(...)?
/** Is this a constructor whose first (non-synthetic) statement is not
     *  of the form this(...)?
     */
    public static boolean isInitialConstructor(JCTree tree) {
        JCMethodInvocation app = firstConstructorCall(tree);
        if (app == null) return false;
        Name meth = name(app.meth);
        return meth == null || meth != meth.table.names._this;
    }

    
Return the first call in a constructor definition. /** Return the first call in a constructor definition. */
    public static JCMethodInvocation firstConstructorCall(JCTree tree) {
        if (!tree.hasTag(METHODDEF)) return null;
        JCMethodDecl md = (JCMethodDecl) tree;
        Names names = md.name.table.names;
        if (md.name != names.init) return null;
        if (md.body == null) return null;
        List<JCStatement> stats = md.body.stats;
        // Synthetic initializations can appear before the super call.
        while (stats.nonEmpty() && isSyntheticInit(stats.head))
            stats = stats.tail;
        if (stats.isEmpty()) return null;
        if (!stats.head.hasTag(EXEC)) return null;
        JCExpressionStatement exec = (JCExpressionStatement) stats.head;
        if (!exec.expr.hasTag(APPLY)) return null;
        return (JCMethodInvocation)exec.expr;
    }

    
Return true if a tree represents a diamond new expr. /** Return true if a tree represents a diamond new expr. */
    public static boolean isDiamond(JCTree tree) {
        switch(tree.getTag()) {
            case TYPEAPPLY: return ((JCTypeApply)tree).getTypeArguments().isEmpty();
            case NEWCLASS: return isDiamond(((JCNewClass)tree).clazz);
            case ANNOTATED_TYPE: return isDiamond(((JCAnnotatedType)tree).underlyingType);
            default: return false;
        }
    }

    
Return true if the given tree represents a type elided anonymous class instance creation. /** Return true if the given tree represents a type elided anonymous class instance creation. */
    public static boolean isAnonymousDiamond(JCTree tree) {
        switch(tree.getTag()) {
            case NEWCLASS:  {
                JCNewClass nc = (JCNewClass)tree;
                return nc.def != null && isDiamond(nc.clazz);
            }
            case ANNOTATED_TYPE: return isAnonymousDiamond(((JCAnnotatedType)tree).underlyingType);
            default: return false;
        }
    }

    public static boolean isEnumInit(JCTree tree) {
        switch (tree.getTag()) {
            case VARDEF:
                return (((JCVariableDecl)tree).mods.flags & ENUM) != 0;
            default:
                return false;
        }
    }

    
set 'polyKind' on given tree /** set 'polyKind' on given tree */
    public static void setPolyKind(JCTree tree, PolyKind pkind) {
        switch (tree.getTag()) {
            case APPLY:
                ((JCMethodInvocation)tree).polyKind = pkind;
                break;
            case NEWCLASS:
                ((JCNewClass)tree).polyKind = pkind;
                break;
            case REFERENCE:
                ((JCMemberReference)tree).refPolyKind = pkind;
                break;
            default:
                throw new AssertionError("Unexpected tree: " + tree);
        }
    }

    
set 'varargsElement' on given tree /** set 'varargsElement' on given tree */
    public static void setVarargsElement(JCTree tree, Type varargsElement) {
        switch (tree.getTag()) {
            case APPLY:
                ((JCMethodInvocation)tree).varargsElement = varargsElement;
                break;
            case NEWCLASS:
                ((JCNewClass)tree).varargsElement = varargsElement;
                break;
            case REFERENCE:
                ((JCMemberReference)tree).varargsElement = varargsElement;
                break;
            default:
                throw new AssertionError("Unexpected tree: " + tree);
        }
    }

    
Return true if the tree corresponds to an expression statement /** Return true if the tree corresponds to an expression statement */
    public static boolean isExpressionStatement(JCExpression tree) {
        switch(tree.getTag()) {
            case PREINC: case PREDEC:
            case POSTINC: case POSTDEC:
            case ASSIGN:
            case BITOR_ASG: case BITXOR_ASG: case BITAND_ASG:
            case SL_ASG: case SR_ASG: case USR_ASG:
            case PLUS_ASG: case MINUS_ASG:
            case MUL_ASG: case DIV_ASG: case MOD_ASG:
            case APPLY: case NEWCLASS:
            case ERRONEOUS:
                return true;
            default:
                return false;
        }
    }

    
Return true if the tree corresponds to a statement /** Return true if the tree corresponds to a statement */
    public static boolean isStatement(JCTree tree) {
        return (tree instanceof JCStatement) &&
                !tree.hasTag(CLASSDEF) &&
                !tree.hasTag(Tag.BLOCK) &&
                !tree.hasTag(METHODDEF);
    }

    
Return true if the AST corresponds to a static select of the kind A.B
/**
     * Return true if the AST corresponds to a static select of the kind A.B
     */
    public static boolean isStaticSelector(JCTree base, Names names) {
        if (base == null)
            return false;
        switch (base.getTag()) {
            case IDENT:
                JCIdent id = (JCIdent)base;
                return id.name != names._this &&
                        id.name != names._super &&
                        isStaticSym(base);
            case SELECT:
                return isStaticSym(base) &&
                    isStaticSelector(((JCFieldAccess)base).selected, names);
            case TYPEAPPLY:
            case TYPEARRAY:
                return true;
            case ANNOTATED_TYPE:
                return isStaticSelector(((JCAnnotatedType)base).underlyingType, names);
            default:
                return false;
        }
    }
    //where
        private static boolean isStaticSym(JCTree tree) {
            Symbol sym = symbol(tree);
            return (sym.kind == TYP || sym.kind == PCK);
        }

    
Return true if a tree represents the null literal. /** Return true if a tree represents the null literal. */
    public static boolean isNull(JCTree tree) {
        if (!tree.hasTag(LITERAL))
            return false;
        JCLiteral lit = (JCLiteral) tree;
        return (lit.typetag == BOT);
    }

    
Return true iff this tree is a child of some annotation. /** Return true iff this tree is a child of some annotation. */
    public static boolean isInAnnotation(Env<?> env, JCTree tree) {
        TreePath tp = TreePath.getPath(env.toplevel, tree);
        if (tp != null) {
            for (Tree t : tp) {
                if (t.getKind() == Tree.Kind.ANNOTATION)
                    return true;
            }
        }
        return false;
    }

    public static String getCommentText(Env<?> env, JCTree tree) {
        DocCommentTable docComments = (tree.hasTag(JCTree.Tag.TOPLEVEL))
                ? ((JCCompilationUnit) tree).docComments
                : env.toplevel.docComments;
        return (docComments == null) ? null : docComments.getCommentText(tree);
    }

    public static DCTree.DCDocComment getCommentTree(Env<?> env, JCTree tree) {
        DocCommentTable docComments = (tree.hasTag(JCTree.Tag.TOPLEVEL))
                ? ((JCCompilationUnit) tree).docComments
                : env.toplevel.docComments;
        return (docComments == null) ? null : docComments.getCommentTree(tree);
    }

    
The position of the first statement in a block, or the position of
 the block itself if it is empty.
/** The position of the first statement in a block, or the position of
     *  the block itself if it is empty.
     */
    public static int firstStatPos(JCTree tree) {
        if (tree.hasTag(BLOCK) && ((JCBlock) tree).stats.nonEmpty())
            return ((JCBlock) tree).stats.head.pos;
        else
            return tree.pos;
    }

    
The end position of given tree, if it is a block with
 defined endpos.
/** The end position of given tree, if it is a block with
     *  defined endpos.
     */
    public static int endPos(JCTree tree) {
        if (tree.hasTag(BLOCK) && ((JCBlock) tree).endpos != Position.NOPOS)
            return ((JCBlock) tree).endpos;
        else if (tree.hasTag(SYNCHRONIZED))
            return endPos(((JCSynchronized) tree).body);
        else if (tree.hasTag(TRY)) {
            JCTry t = (JCTry) tree;
            return endPos((t.finalizer != null) ? t.finalizer
                          : (t.catchers.nonEmpty() ? t.catchers.last().body : t.body));
        } else
            return tree.pos;
    }


    
Get the start position for a tree node.  The start position is
defined to be the position of the first character of the first
token of the node's source text.
Params:
tree –  The tree node/** Get the start position for a tree node.  The start position is
     * defined to be the position of the first character of the first
     * token of the node's source text.
     * @param tree  The tree node
     */
    public static int getStartPos(JCTree tree) {
        if (tree == null)
            return Position.NOPOS;

        switch(tree.getTag()) {
            case MODULEDEF: {
                JCModuleDecl md = (JCModuleDecl)tree;
                return md.mods.annotations.isEmpty() ? md.pos :
                       md.mods.annotations.head.pos;
            }
            case PACKAGEDEF: {
                JCPackageDecl pd = (JCPackageDecl)tree;
                return pd.annotations.isEmpty() ? pd.pos :
                       pd.annotations.head.pos;
            }
            case APPLY:
                return getStartPos(((JCMethodInvocation) tree).meth);
            case ASSIGN:
                return getStartPos(((JCAssign) tree).lhs);
            case BITOR_ASG: case BITXOR_ASG: case BITAND_ASG:
            case SL_ASG: case SR_ASG: case USR_ASG:
            case PLUS_ASG: case MINUS_ASG: case MUL_ASG:
            case DIV_ASG: case MOD_ASG:
            case OR: case AND: case BITOR:
            case BITXOR: case BITAND: case EQ:
            case NE: case LT: case GT:
            case LE: case GE: case SL:
            case SR: case USR: case PLUS:
            case MINUS: case MUL: case DIV:
            case MOD:
            case POSTINC:
            case POSTDEC:
                return getStartPos(((JCOperatorExpression) tree).getOperand(LEFT));
            case CLASSDEF: {
                JCClassDecl node = (JCClassDecl)tree;
                if (node.mods.pos != Position.NOPOS)
                    return node.mods.pos;
                break;
            }
            case CONDEXPR:
                return getStartPos(((JCConditional) tree).cond);
            case EXEC:
                return getStartPos(((JCExpressionStatement) tree).expr);
            case INDEXED:
                return getStartPos(((JCArrayAccess) tree).indexed);
            case METHODDEF: {
                JCMethodDecl node = (JCMethodDecl)tree;
                if (node.mods.pos != Position.NOPOS)
                    return node.mods.pos;
                if (node.typarams.nonEmpty()) // List.nil() used for no typarams
                    return getStartPos(node.typarams.head);
                return node.restype == null ? node.pos : getStartPos(node.restype);
            }
            case SELECT:
                return getStartPos(((JCFieldAccess) tree).selected);
            case TYPEAPPLY:
                return getStartPos(((JCTypeApply) tree).clazz);
            case TYPEARRAY:
                return getStartPos(((JCArrayTypeTree) tree).elemtype);
            case TYPETEST:
                return getStartPos(((JCInstanceOf) tree).expr);
            case ANNOTATED_TYPE: {
                JCAnnotatedType node = (JCAnnotatedType) tree;
                if (node.annotations.nonEmpty()) {
                    if (node.underlyingType.hasTag(TYPEARRAY) ||
                            node.underlyingType.hasTag(SELECT)) {
                        return getStartPos(node.underlyingType);
                    } else {
                        return getStartPos(node.annotations.head);
                    }
                } else {
                    return getStartPos(node.underlyingType);
                }
            }
            case NEWCLASS: {
                JCNewClass node = (JCNewClass)tree;
                if (node.encl != null)
                    return getStartPos(node.encl);
                break;
            }
            case VARDEF: {
                JCVariableDecl node = (JCVariableDecl)tree;
                if (node.mods.pos != Position.NOPOS) {
                    return node.mods.pos;
                } else if (node.vartype == null) {
                    //if there's no type (partially typed lambda parameter)
                    //simply return node position
                    return node.pos;
                } else {
                    return getStartPos(node.vartype);
                }
            }
            case ERRONEOUS: {
                JCErroneous node = (JCErroneous)tree;
                if (node.errs != null && node.errs.nonEmpty())
                    return getStartPos(node.errs.head);
            }
        }
        return tree.pos;
    }

    
The end position of given tree, given  a table of end positions generated by the parser
/** The end position of given tree, given  a table of end positions generated by the parser
     */
    public static int getEndPos(JCTree tree, EndPosTable endPosTable) {
        if (tree == null)
            return Position.NOPOS;

        if (endPosTable == null) {
            // fall back on limited info in the tree
            return endPos(tree);
        }

        int mapPos = endPosTable.getEndPos(tree);
        if (mapPos != Position.NOPOS)
            return mapPos;

        switch(tree.getTag()) {
            case BITOR_ASG: case BITXOR_ASG: case BITAND_ASG:
            case SL_ASG: case SR_ASG: case USR_ASG:
            case PLUS_ASG: case MINUS_ASG: case MUL_ASG:
            case DIV_ASG: case MOD_ASG:
            case OR: case AND: case BITOR:
            case BITXOR: case BITAND: case EQ:
            case NE: case LT: case GT:
            case LE: case GE: case SL:
            case SR: case USR: case PLUS:
            case MINUS: case MUL: case DIV:
            case MOD:
            case POS:
            case NEG:
            case NOT:
            case COMPL:
            case PREINC:
            case PREDEC:
                return getEndPos(((JCOperatorExpression) tree).getOperand(RIGHT), endPosTable);
            case CASE:
                return getEndPos(((JCCase) tree).stats.last(), endPosTable);
            case CATCH:
                return getEndPos(((JCCatch) tree).body, endPosTable);
            case CONDEXPR:
                return getEndPos(((JCConditional) tree).falsepart, endPosTable);
            case FORLOOP:
                return getEndPos(((JCForLoop) tree).body, endPosTable);
            case FOREACHLOOP:
                return getEndPos(((JCEnhancedForLoop) tree).body, endPosTable);
            case IF: {
                JCIf node = (JCIf)tree;
                if (node.elsepart == null) {
                    return getEndPos(node.thenpart, endPosTable);
                } else {
                    return getEndPos(node.elsepart, endPosTable);
                }
            }
            case LABELLED:
                return getEndPos(((JCLabeledStatement) tree).body, endPosTable);
            case MODIFIERS:
                return getEndPos(((JCModifiers) tree).annotations.last(), endPosTable);
            case SYNCHRONIZED:
                return getEndPos(((JCSynchronized) tree).body, endPosTable);
            case TOPLEVEL:
                return getEndPos(((JCCompilationUnit) tree).defs.last(), endPosTable);
            case TRY: {
                JCTry node = (JCTry)tree;
                if (node.finalizer != null) {
                    return getEndPos(node.finalizer, endPosTable);
                } else if (!node.catchers.isEmpty()) {
                    return getEndPos(node.catchers.last(), endPosTable);
                } else {
                    return getEndPos(node.body, endPosTable);
                }
            }
            case WILDCARD:
                return getEndPos(((JCWildcard) tree).inner, endPosTable);
            case TYPECAST:
                return getEndPos(((JCTypeCast) tree).expr, endPosTable);
            case TYPETEST:
                return getEndPos(((JCInstanceOf) tree).clazz, endPosTable);
            case WHILELOOP:
                return getEndPos(((JCWhileLoop) tree).body, endPosTable);
            case ANNOTATED_TYPE:
                return getEndPos(((JCAnnotatedType) tree).underlyingType, endPosTable);
            case ERRONEOUS: {
                JCErroneous node = (JCErroneous)tree;
                if (node.errs != null && node.errs.nonEmpty())
                    return getEndPos(node.errs.last(), endPosTable);
            }
        }
        return Position.NOPOS;
    }


    
A DiagnosticPosition with the preferred position set to the
 end position of given tree, if it is a block with
 defined endpos.
/** A DiagnosticPosition with the preferred position set to the
     *  end position of given tree, if it is a block with
     *  defined endpos.
     */
    public static DiagnosticPosition diagEndPos(final JCTree tree) {
        final int endPos = TreeInfo.endPos(tree);
        return new DiagnosticPosition() {
            public JCTree getTree() { return tree; }
            public int getStartPosition() { return TreeInfo.getStartPos(tree); }
            public int getPreferredPosition() { return endPos; }
            public int getEndPosition(EndPosTable endPosTable) {
                return TreeInfo.getEndPos(tree, endPosTable);
            }
        };
    }

    
The position of the finalizer of given try/synchronized statement.
/** The position of the finalizer of given try/synchronized statement.
     */
    public static int finalizerPos(JCTree tree) {
        if (tree.hasTag(TRY)) {
            JCTry t = (JCTry) tree;
            Assert.checkNonNull(t.finalizer);
            return firstStatPos(t.finalizer);
        } else if (tree.hasTag(SYNCHRONIZED)) {
            return endPos(((JCSynchronized) tree).body);
        } else {
            throw new AssertionError();
        }
    }

    
Find the position for reporting an error about a symbol, where
 that symbol is defined somewhere in the given tree. /** Find the position for reporting an error about a symbol, where
     *  that symbol is defined somewhere in the given tree. */
    public static int positionFor(final Symbol sym, final JCTree tree) {
        JCTree decl = declarationFor(sym, tree);
        return ((decl != null) ? decl : tree).pos;
    }

    
Find the position for reporting an error about a symbol, where
 that symbol is defined somewhere in the given tree. /** Find the position for reporting an error about a symbol, where
     *  that symbol is defined somewhere in the given tree. */
    public static DiagnosticPosition diagnosticPositionFor(final Symbol sym, final JCTree tree) {
        JCTree decl = declarationFor(sym, tree);
        return ((decl != null) ? decl : tree).pos();
    }

    
Find the declaration for a symbol, where
 that symbol is defined somewhere in the given tree. /** Find the declaration for a symbol, where
     *  that symbol is defined somewhere in the given tree. */
    public static JCTree declarationFor(final Symbol sym, final JCTree tree) {
        class DeclScanner extends TreeScanner {
            JCTree result = null;
            public void scan(JCTree tree) {
                if (tree!=null && result==null)
                    tree.accept(this);
            }
            public void visitTopLevel(JCCompilationUnit that) {
                if (that.packge == sym) result = that;
                else super.visitTopLevel(that);
            }
            public void visitModuleDef(JCModuleDecl that) {
                if (that.sym == sym) result = that;
                // no need to scan within module declaration
            }
            public void visitPackageDef(JCPackageDecl that) {
                if (that.packge == sym) result = that;
                else super.visitPackageDef(that);
            }
            public void visitClassDef(JCClassDecl that) {
                if (that.sym == sym) result = that;
                else super.visitClassDef(that);
            }
            public void visitMethodDef(JCMethodDecl that) {
                if (that.sym == sym) result = that;
                else super.visitMethodDef(that);
            }
            public void visitVarDef(JCVariableDecl that) {
                if (that.sym == sym) result = that;
                else super.visitVarDef(that);
            }
            public void visitTypeParameter(JCTypeParameter that) {
                if (that.type != null && that.type.tsym == sym) result = that;
                else super.visitTypeParameter(that);
            }
        }
        DeclScanner s = new DeclScanner();
        tree.accept(s);
        return s.result;
    }

    public static Env<AttrContext> scopeFor(JCTree node, JCCompilationUnit unit) {
        return scopeFor(pathFor(node, unit));
    }

    public static Env<AttrContext> scopeFor(List<JCTree> path) {
        // TODO: not implemented yet
        throw new UnsupportedOperationException("not implemented yet");
    }

    public static List<JCTree> pathFor(final JCTree node, final JCCompilationUnit unit) {
        class Result extends Error {
            static final long serialVersionUID = -5942088234594905625L;
            List<JCTree> path;
            Result(List<JCTree> path) {
                this.path = path;
            }
        }
        class PathFinder extends TreeScanner {
            List<JCTree> path = List.nil();
            public void scan(JCTree tree) {
                if (tree != null) {
                    path = path.prepend(tree);
                    if (tree == node)
                        throw new Result(path);
                    super.scan(tree);
                    path = path.tail;
                }
            }
        }
        try {
            new PathFinder().scan(unit);
        } catch (Result result) {
            return result.path;
        }
        return List.nil();
    }

    
Return the statement referenced by a label.
 If the label refers to a loop or switch, return that switch
 otherwise return the labelled statement itself
/** Return the statement referenced by a label.
     *  If the label refers to a loop or switch, return that switch
     *  otherwise return the labelled statement itself
     */
    public static JCTree referencedStatement(JCLabeledStatement tree) {
        JCTree t = tree;
        do t = ((JCLabeledStatement) t).body;
        while (t.hasTag(LABELLED));
        switch (t.getTag()) {
        case DOLOOP: case WHILELOOP: case FORLOOP: case FOREACHLOOP: case SWITCH:
            return t;
        default:
            return tree;
        }
    }

    
Skip parens and return the enclosed expression
/** Skip parens and return the enclosed expression
     */
    public static JCExpression skipParens(JCExpression tree) {
        while (tree.hasTag(PARENS)) {
            tree = ((JCParens) tree).expr;
        }
        return tree;
    }

    
Skip parens and return the enclosed expression
/** Skip parens and return the enclosed expression
     */
    public static JCTree skipParens(JCTree tree) {
        if (tree.hasTag(PARENS))
            return skipParens((JCParens)tree);
        else
            return tree;
    }

    
Return the types of a list of trees.
/** Return the types of a list of trees.
     */
    public static List<Type> types(List<? extends JCTree> trees) {
        ListBuffer<Type> ts = new ListBuffer<>();
        for (List<? extends JCTree> l = trees; l.nonEmpty(); l = l.tail)
            ts.append(l.head.type);
        return ts.toList();
    }

    
If this tree is an identifier or a field or a parameterized type,
 return its name, otherwise return null.
/** If this tree is an identifier or a field or a parameterized type,
     *  return its name, otherwise return null.
     */
    public static Name name(JCTree tree) {
        switch (tree.getTag()) {
        case IDENT:
            return ((JCIdent) tree).name;
        case SELECT:
            return ((JCFieldAccess) tree).name;
        case TYPEAPPLY:
            return name(((JCTypeApply) tree).clazz);
        default:
            return null;
        }
    }

    
If this tree is a qualified identifier, its return fully qualified name,
 otherwise return null.
/** If this tree is a qualified identifier, its return fully qualified name,
     *  otherwise return null.
     */
    public static Name fullName(JCTree tree) {
        tree = skipParens(tree);
        switch (tree.getTag()) {
        case IDENT:
            return ((JCIdent) tree).name;
        case SELECT:
            Name sname = fullName(((JCFieldAccess) tree).selected);
            return sname == null ? null : sname.append('.', name(tree));
        default:
            return null;
        }
    }

    public static Symbol symbolFor(JCTree node) {
        Symbol sym = symbolForImpl(node);

        return sym != null ? sym.baseSymbol() : null;
    }

    private static Symbol symbolForImpl(JCTree node) {
        node = skipParens(node);
        switch (node.getTag()) {
        case TOPLEVEL:
            JCCompilationUnit cut = (JCCompilationUnit) node;
            JCModuleDecl moduleDecl = cut.getModuleDecl();
            if (isModuleInfo(cut) && moduleDecl != null)
                return symbolFor(moduleDecl);
            return cut.packge;
        case MODULEDEF:
            return ((JCModuleDecl) node).sym;
        case PACKAGEDEF:
            return ((JCPackageDecl) node).packge;
        case CLASSDEF:
            return ((JCClassDecl) node).sym;
        case METHODDEF:
            return ((JCMethodDecl) node).sym;
        case VARDEF:
            return ((JCVariableDecl) node).sym;
        case IDENT:
            return ((JCIdent) node).sym;
        case SELECT:
            return ((JCFieldAccess) node).sym;
        case REFERENCE:
            return ((JCMemberReference) node).sym;
        case NEWCLASS:
            return ((JCNewClass) node).constructor;
        case APPLY:
            return symbolFor(((JCMethodInvocation) node).meth);
        case TYPEAPPLY:
            return symbolFor(((JCTypeApply) node).clazz);
        case ANNOTATION:
        case TYPE_ANNOTATION:
        case TYPEPARAMETER:
            if (node.type != null)
                return node.type.tsym;
            return null;
        default:
            return null;
        }
    }

    public static boolean isDeclaration(JCTree node) {
        node = skipParens(node);
        switch (node.getTag()) {
        case PACKAGEDEF:
        case CLASSDEF:
        case METHODDEF:
        case VARDEF:
            return true;
        default:
            return false;
        }
    }

    
If this tree is an identifier or a field, return its symbol,
 otherwise return null.
/** If this tree is an identifier or a field, return its symbol,
     *  otherwise return null.
     */
    public static Symbol symbol(JCTree tree) {
        tree = skipParens(tree);
        switch (tree.getTag()) {
        case IDENT:
            return ((JCIdent) tree).sym;
        case SELECT:
            return ((JCFieldAccess) tree).sym;
        case TYPEAPPLY:
            return symbol(((JCTypeApply) tree).clazz);
        case ANNOTATED_TYPE:
            return symbol(((JCAnnotatedType) tree).underlyingType);
        case REFERENCE:
            return ((JCMemberReference) tree).sym;
        default:
            return null;
        }
    }

    
Return true if this is a nonstatic selection. /** Return true if this is a nonstatic selection. */
    public static boolean nonstaticSelect(JCTree tree) {
        tree = skipParens(tree);
        if (!tree.hasTag(SELECT)) return false;
        JCFieldAccess s = (JCFieldAccess) tree;
        Symbol e = symbol(s.selected);
        return e == null || (e.kind != PCK && e.kind != TYP);
    }

    
If this tree is an identifier or a field, set its symbol, otherwise skip.
/** If this tree is an identifier or a field, set its symbol, otherwise skip.
     */
    public static void setSymbol(JCTree tree, Symbol sym) {
        tree = skipParens(tree);
        switch (tree.getTag()) {
        case IDENT:
            ((JCIdent) tree).sym = sym; break;
        case SELECT:
            ((JCFieldAccess) tree).sym = sym; break;
        default:
        }
    }

    
If this tree is a declaration or a block, return its flags field,
 otherwise return 0.
/** If this tree is a declaration or a block, return its flags field,
     *  otherwise return 0.
     */
    public static long flags(JCTree tree) {
        switch (tree.getTag()) {
        case VARDEF:
            return ((JCVariableDecl) tree).mods.flags;
        case METHODDEF:
            return ((JCMethodDecl) tree).mods.flags;
        case CLASSDEF:
            return ((JCClassDecl) tree).mods.flags;
        case BLOCK:
            return ((JCBlock) tree).flags;
        default:
            return 0;
        }
    }

    
Return first (smallest) flag in `flags':
 pre: flags != 0
/** Return first (smallest) flag in `flags':
     *  pre: flags != 0
     */
    public static long firstFlag(long flags) {
        long flag = 1;
        while ((flag & flags & ExtendedStandardFlags) == 0)
            flag = flag << 1;
        return flag;
    }

    
Return flags as a string, separated by " ".
/** Return flags as a string, separated by " ".
     */
    public static String flagNames(long flags) {
        return Flags.toString(flags & ExtendedStandardFlags).trim();
    }

    
Operator precedences values.
/** Operator precedences values.
     */
    public static final int
        notExpression = -1,   // not an expression
        noPrec = 0,           // no enclosing expression
        assignPrec = 1,
        assignopPrec = 2,
        condPrec = 3,
        orPrec = 4,
        andPrec = 5,
        bitorPrec = 6,
        bitxorPrec = 7,
        bitandPrec = 8,
        eqPrec = 9,
        ordPrec = 10,
        shiftPrec = 11,
        addPrec = 12,
        mulPrec = 13,
        prefixPrec = 14,
        postfixPrec = 15,
        precCount = 16;


    
Map operators to their precedence levels.
/** Map operators to their precedence levels.
     */
    public static int opPrec(JCTree.Tag op) {
        switch(op) {
        case POS:
        case NEG:
        case NOT:
        case COMPL:
        case PREINC:
        case PREDEC: return prefixPrec;
        case POSTINC:
        case POSTDEC:
        case NULLCHK: return postfixPrec;
        case ASSIGN: return assignPrec;
        case BITOR_ASG:
        case BITXOR_ASG:
        case BITAND_ASG:
        case SL_ASG:
        case SR_ASG:
        case USR_ASG:
        case PLUS_ASG:
        case MINUS_ASG:
        case MUL_ASG:
        case DIV_ASG:
        case MOD_ASG: return assignopPrec;
        case OR: return orPrec;
        case AND: return andPrec;
        case EQ:
        case NE: return eqPrec;
        case LT:
        case GT:
        case LE:
        case GE: return ordPrec;
        case BITOR: return bitorPrec;
        case BITXOR: return bitxorPrec;
        case BITAND: return bitandPrec;
        case SL:
        case SR:
        case USR: return shiftPrec;
        case PLUS:
        case MINUS: return addPrec;
        case MUL:
        case DIV:
        case MOD: return mulPrec;
        case TYPETEST: return ordPrec;
        default: throw new AssertionError();
        }
    }

    static Tree.Kind tagToKind(JCTree.Tag tag) {
        switch (tag) {
        // Postfix expressions
        case POSTINC:           // _ ++
            return Tree.Kind.POSTFIX_INCREMENT;
        case POSTDEC:           // _ --
            return Tree.Kind.POSTFIX_DECREMENT;

        // Unary operators
        case PREINC:            // ++ _
            return Tree.Kind.PREFIX_INCREMENT;
        case PREDEC:            // -- _
            return Tree.Kind.PREFIX_DECREMENT;
        case POS:               // +
            return Tree.Kind.UNARY_PLUS;
        case NEG:               // -
            return Tree.Kind.UNARY_MINUS;
        case COMPL:             // ~
            return Tree.Kind.BITWISE_COMPLEMENT;
        case NOT:               // !
            return Tree.Kind.LOGICAL_COMPLEMENT;

        // Binary operators

        // Multiplicative operators
        case MUL:               // *
            return Tree.Kind.MULTIPLY;
        case DIV:               // /
            return Tree.Kind.DIVIDE;
        case MOD:               // %
            return Tree.Kind.REMAINDER;

        // Additive operators
        case PLUS:              // +
            return Tree.Kind.PLUS;
        case MINUS:             // -
            return Tree.Kind.MINUS;

        // Shift operators
        case SL:                // <<
            return Tree.Kind.LEFT_SHIFT;
        case SR:                // >>
            return Tree.Kind.RIGHT_SHIFT;
        case USR:               // >>>
            return Tree.Kind.UNSIGNED_RIGHT_SHIFT;

        // Relational operators
        case LT:                // <
            return Tree.Kind.LESS_THAN;
        case GT:                // >
            return Tree.Kind.GREATER_THAN;
        case LE:                // <=
            return Tree.Kind.LESS_THAN_EQUAL;
        case GE:                // >=
            return Tree.Kind.GREATER_THAN_EQUAL;

        // Equality operators
        case EQ:                // ==
            return Tree.Kind.EQUAL_TO;
        case NE:                // !=
            return Tree.Kind.NOT_EQUAL_TO;

        // Bitwise and logical operators
        case BITAND:            // &
            return Tree.Kind.AND;
        case BITXOR:            // ^
            return Tree.Kind.XOR;
        case BITOR:             // |
            return Tree.Kind.OR;

        // Conditional operators
        case AND:               // &&
            return Tree.Kind.CONDITIONAL_AND;
        case OR:                // ||
            return Tree.Kind.CONDITIONAL_OR;

        // Assignment operators
        case MUL_ASG:           // *=
            return Tree.Kind.MULTIPLY_ASSIGNMENT;
        case DIV_ASG:           // /=
            return Tree.Kind.DIVIDE_ASSIGNMENT;
        case MOD_ASG:           // %=
            return Tree.Kind.REMAINDER_ASSIGNMENT;
        case PLUS_ASG:          // +=
            return Tree.Kind.PLUS_ASSIGNMENT;
        case MINUS_ASG:         // -=
            return Tree.Kind.MINUS_ASSIGNMENT;
        case SL_ASG:            // <<=
            return Tree.Kind.LEFT_SHIFT_ASSIGNMENT;
        case SR_ASG:            // >>=
            return Tree.Kind.RIGHT_SHIFT_ASSIGNMENT;
        case USR_ASG:           // >>>=
            return Tree.Kind.UNSIGNED_RIGHT_SHIFT_ASSIGNMENT;
        case BITAND_ASG:        // &=
            return Tree.Kind.AND_ASSIGNMENT;
        case BITXOR_ASG:        // ^=
            return Tree.Kind.XOR_ASSIGNMENT;
        case BITOR_ASG:         // |=
            return Tree.Kind.OR_ASSIGNMENT;

        // Null check (implementation detail), for example, __.getClass()
        case NULLCHK:
            return Tree.Kind.OTHER;

        case ANNOTATION:
            return Tree.Kind.ANNOTATION;
        case TYPE_ANNOTATION:
            return Tree.Kind.TYPE_ANNOTATION;

        case EXPORTS:
            return Tree.Kind.EXPORTS;
        case OPENS:
            return Tree.Kind.OPENS;

        default:
            return null;
        }
    }

    
Returns the underlying type of the tree if it is an annotated type,
or the tree itself otherwise.
/**
     * Returns the underlying type of the tree if it is an annotated type,
     * or the tree itself otherwise.
     */
    public static JCExpression typeIn(JCExpression tree) {
        switch (tree.getTag()) {
        case ANNOTATED_TYPE:
            return ((JCAnnotatedType)tree).underlyingType;
        case IDENT: /* simple names */
        case TYPEIDENT: /* primitive name */
        case SELECT: /* qualified name */
        case TYPEARRAY: /* array types */
        case WILDCARD: /* wild cards */
        case TYPEPARAMETER: /* type parameters */
        case TYPEAPPLY: /* parameterized types */
        case ERRONEOUS: /* error tree TODO: needed for BadCast JSR308 test case. Better way? */
            return tree;
        default:
            throw new AssertionError("Unexpected type tree: " + tree);
        }
    }

    /* Return the inner-most type of a type tree.
     * For an array that contains an annotated type, return that annotated type.
     * TODO: currently only used by Pretty. Describe behavior better.
     */
    public static JCTree innermostType(JCTree type) {
        JCTree lastAnnotatedType = null;
        JCTree cur = type;
        loop: while (true) {
            switch (cur.getTag()) {
            case TYPEARRAY:
                lastAnnotatedType = null;
                cur = ((JCArrayTypeTree)cur).elemtype;
                break;
            case WILDCARD:
                lastAnnotatedType = null;
                cur = ((JCWildcard)cur).inner;
                break;
            case ANNOTATED_TYPE:
                lastAnnotatedType = cur;
                cur = ((JCAnnotatedType)cur).underlyingType;
                break;
            default:
                break loop;
            }
        }
        if (lastAnnotatedType!=null) {
            return lastAnnotatedType;
        } else {
            return cur;
        }
    }

    private static class TypeAnnotationFinder extends TreeScanner {
        public boolean foundTypeAnno = false;

        @Override
        public void scan(JCTree tree) {
            if (foundTypeAnno || tree == null)
                return;
            super.scan(tree);
        }

        public void visitAnnotation(JCAnnotation tree) {
            foundTypeAnno = foundTypeAnno || tree.hasTag(TYPE_ANNOTATION);
        }
    }

    public static boolean containsTypeAnnotation(JCTree e) {
        TypeAnnotationFinder finder = new TypeAnnotationFinder();
        finder.scan(e);
        return finder.foundTypeAnno;
    }

    public static boolean isModuleInfo(JCCompilationUnit tree) {
        return tree.sourcefile.isNameCompatible("module-info", JavaFileObject.Kind.SOURCE)
                && tree.getModuleDecl() != null;
    }

    public static JCModuleDecl getModule(JCCompilationUnit t) {
        if (t.defs.nonEmpty()) {
            JCTree def = t.defs.head;
            if (def.hasTag(MODULEDEF))
                return (JCModuleDecl) def;
        }
        return null;
    }

    public static boolean isPackageInfo(JCCompilationUnit tree) {
        return tree.sourcefile.isNameCompatible("package-info", JavaFileObject.Kind.SOURCE);
    }
}