/*
 * Copyright (c) 2005, 2017, 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.api;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.text.BreakIterator;
import java.util.Collections;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.WeakHashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.annotation.processing.ProcessingEnvironment;
import javax.lang.model.element.AnnotationMirror;
import javax.lang.model.element.AnnotationValue;
import javax.lang.model.element.Element;
import javax.lang.model.element.ElementKind;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.element.Modifier;
import javax.lang.model.element.NestingKind;
import javax.lang.model.element.PackageElement;
import javax.lang.model.element.TypeElement;
import javax.lang.model.type.DeclaredType;
import javax.lang.model.type.TypeKind;
import javax.lang.model.type.TypeMirror;
import javax.tools.Diagnostic;
import javax.tools.FileObject;
import javax.tools.ForwardingFileObject;
import javax.tools.JavaCompiler;
import javax.tools.JavaFileManager;
import javax.tools.JavaFileObject;
import javax.tools.JavaFileObject.Kind;
import javax.tools.StandardLocation;

import com.sun.source.doctree.DocCommentTree;
import com.sun.source.doctree.DocTree;
import com.sun.source.doctree.EndElementTree;
import com.sun.source.doctree.StartElementTree;
import com.sun.source.tree.CatchTree;
import com.sun.source.tree.CompilationUnitTree;
import com.sun.source.tree.Scope;
import com.sun.source.tree.Tree;
import com.sun.source.util.DocSourcePositions;
import com.sun.source.util.DocTreePath;
import com.sun.source.util.DocTreeScanner;
import com.sun.source.util.DocTrees;
import com.sun.source.util.JavacTask;
import com.sun.source.util.SimpleDocTreeVisitor;
import com.sun.source.util.TreePath;
import com.sun.tools.javac.code.Flags;
import com.sun.tools.javac.code.Scope.NamedImportScope;
import com.sun.tools.javac.code.Scope.StarImportScope;
import com.sun.tools.javac.code.Scope.WriteableScope;
import com.sun.tools.javac.code.Symbol;
import com.sun.tools.javac.code.Symbol.ClassSymbol;
import com.sun.tools.javac.code.Symbol.MethodSymbol;
import com.sun.tools.javac.code.Symbol.ModuleSymbol;
import com.sun.tools.javac.code.Symbol.PackageSymbol;
import com.sun.tools.javac.code.Symbol.TypeSymbol;
import com.sun.tools.javac.code.Symbol.VarSymbol;
import com.sun.tools.javac.code.Symtab;
import com.sun.tools.javac.code.Type;
import com.sun.tools.javac.code.Type.ArrayType;
import com.sun.tools.javac.code.Type.ClassType;
import com.sun.tools.javac.code.Type.ErrorType;
import com.sun.tools.javac.code.Type.UnionClassType;
import com.sun.tools.javac.code.Types;
import com.sun.tools.javac.code.Types.TypeRelation;
import com.sun.tools.javac.comp.Attr;
import com.sun.tools.javac.comp.AttrContext;
import com.sun.tools.javac.comp.Enter;
import com.sun.tools.javac.comp.Env;
import com.sun.tools.javac.comp.MemberEnter;
import com.sun.tools.javac.comp.Modules;
import com.sun.tools.javac.comp.Resolve;
import com.sun.tools.javac.file.BaseFileManager;
import com.sun.tools.javac.model.JavacElements;
import com.sun.tools.javac.parser.DocCommentParser;
import com.sun.tools.javac.parser.ParserFactory;
import com.sun.tools.javac.parser.Tokens.Comment;
import com.sun.tools.javac.parser.Tokens.Comment.CommentStyle;
import com.sun.tools.javac.processing.JavacProcessingEnvironment;
import com.sun.tools.javac.resources.CompilerProperties.Errors;
import com.sun.tools.javac.resources.CompilerProperties.Notes;
import com.sun.tools.javac.resources.CompilerProperties.Warnings;
import com.sun.tools.javac.tree.DCTree;
import com.sun.tools.javac.tree.DCTree.DCBlockTag;
import com.sun.tools.javac.tree.DCTree.DCDocComment;
import com.sun.tools.javac.tree.DCTree.DCEndPosTree;
import com.sun.tools.javac.tree.DCTree.DCErroneous;
import com.sun.tools.javac.tree.DCTree.DCIdentifier;
import com.sun.tools.javac.tree.DCTree.DCParam;
import com.sun.tools.javac.tree.DCTree.DCReference;
import com.sun.tools.javac.tree.DCTree.DCText;
import com.sun.tools.javac.tree.DocCommentTable;
import com.sun.tools.javac.tree.DocTreeMaker;
import com.sun.tools.javac.tree.EndPosTable;
import com.sun.tools.javac.tree.JCTree;
import com.sun.tools.javac.tree.JCTree.JCBlock;
import com.sun.tools.javac.tree.JCTree.JCCatch;
import com.sun.tools.javac.tree.JCTree.JCClassDecl;
import com.sun.tools.javac.tree.JCTree.JCCompilationUnit;
import com.sun.tools.javac.tree.JCTree.JCExpression;
import com.sun.tools.javac.tree.JCTree.JCIdent;
import com.sun.tools.javac.tree.JCTree.JCMethodDecl;
import com.sun.tools.javac.tree.JCTree.JCVariableDecl;
import com.sun.tools.javac.tree.TreeCopier;
import com.sun.tools.javac.tree.TreeInfo;
import com.sun.tools.javac.tree.TreeMaker;
import com.sun.tools.javac.util.Abort;
import com.sun.tools.javac.util.Assert;
import com.sun.tools.javac.util.Context;
import com.sun.tools.javac.util.DefinedBy;
import com.sun.tools.javac.util.DefinedBy.Api;
import com.sun.tools.javac.util.DiagnosticSource;
import com.sun.tools.javac.util.JCDiagnostic;
import com.sun.tools.javac.util.JCDiagnostic.DiagnosticFlag;
import com.sun.tools.javac.util.List;
import com.sun.tools.javac.util.ListBuffer;
import com.sun.tools.javac.util.Log;
import com.sun.tools.javac.util.Name;
import com.sun.tools.javac.util.Names;
import com.sun.tools.javac.util.Pair;
import com.sun.tools.javac.util.Position;

import static com.sun.tools.javac.code.Kinds.Kind.*;
import static com.sun.tools.javac.code.TypeTag.*;

Provides an implementation of 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.
Author:
Peter von der Ahé/**
 * Provides an implementation of 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></p>
 *
 * @author Peter von der Ah&eacute;
 */
public class JavacTrees extends DocTrees {

    // in a world of a single context per compilation, these would all be final
    private Modules modules;
    private Resolve resolve;
    private Enter enter;
    private Log log;
    private MemberEnter memberEnter;
    private Attr attr;
    private TreeMaker treeMaker;
    private JavacElements elements;
    private JavacTaskImpl javacTaskImpl;
    private Names names;
    private Types types;
    private DocTreeMaker docTreeMaker;
    private BreakIterator breakIterator;
    private JavaFileManager fileManager;
    private ParserFactory parser;
    private Symtab syms;

    private final Map<Type, Type> extraType2OriginalMap = new WeakHashMap<>();

    // called reflectively from Trees.instance(CompilationTask task)
    public static JavacTrees instance(JavaCompiler.CompilationTask task) {
        if (!(task instanceof BasicJavacTask))
            throw new IllegalArgumentException();
        return instance(((BasicJavacTask)task).getContext());
    }

    // called reflectively from Trees.instance(ProcessingEnvironment env)
    public static JavacTrees instance(ProcessingEnvironment env) {
        if (!(env instanceof JavacProcessingEnvironment))
            throw new IllegalArgumentException();
        return instance(((JavacProcessingEnvironment)env).getContext());
    }

    public static JavacTrees instance(Context context) {
        JavacTrees instance = context.get(JavacTrees.class);
        if (instance == null)
            instance = new JavacTrees(context);
        return instance;
    }

    protected JavacTrees(Context context) {
        this.breakIterator = null;
        context.put(JavacTrees.class, this);
        init(context);
    }

    public void updateContext(Context context) {
        init(context);
    }

    private void init(Context context) {
        modules = Modules.instance(context);
        attr = Attr.instance(context);
        enter = Enter.instance(context);
        elements = JavacElements.instance(context);
        log = Log.instance(context);
        resolve = Resolve.instance(context);
        treeMaker = TreeMaker.instance(context);
        memberEnter = MemberEnter.instance(context);
        names = Names.instance(context);
        types = Types.instance(context);
        docTreeMaker = DocTreeMaker.instance(context);
        parser = ParserFactory.instance(context);
        syms = Symtab.instance(context);
        fileManager = context.get(JavaFileManager.class);
        JavacTask t = context.get(JavacTask.class);
        if (t instanceof JavacTaskImpl)
            javacTaskImpl = (JavacTaskImpl) t;
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public BreakIterator getBreakIterator() {
        return breakIterator;
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public DocSourcePositions getSourcePositions() {
        return new DocSourcePositions() {
                @Override @DefinedBy(Api.COMPILER_TREE)
                public long getStartPosition(CompilationUnitTree file, Tree tree) {
                    return TreeInfo.getStartPos((JCTree) tree);
                }

                @Override @DefinedBy(Api.COMPILER_TREE)
                public long getEndPosition(CompilationUnitTree file, Tree tree) {
                    EndPosTable endPosTable = ((JCCompilationUnit) file).endPositions;
                    return TreeInfo.getEndPos((JCTree) tree, endPosTable);
                }

                @Override @DefinedBy(Api.COMPILER_TREE)
                public long getStartPosition(CompilationUnitTree file, DocCommentTree comment, DocTree tree) {
                    return ((DCTree) tree).getSourcePosition((DCDocComment) comment);
                }
                @Override  @DefinedBy(Api.COMPILER_TREE) @SuppressWarnings("fallthrough")
                public long getEndPosition(CompilationUnitTree file, DocCommentTree comment, DocTree tree) {
                    DCDocComment dcComment = (DCDocComment) comment;
                    if (tree instanceof DCEndPosTree) {
                        int endPos = ((DCEndPosTree) tree).getEndPos(dcComment);

                        if (endPos != Position.NOPOS) {
                            return endPos;
                        }
                    }
                    int correction = 0;
                    switch (tree.getKind()) {
                        case TEXT:
                            DCText text = (DCText) tree;

                            return dcComment.comment.getSourcePos(text.pos + text.text.length());
                        case ERRONEOUS:
                            DCErroneous err = (DCErroneous) tree;

                            return dcComment.comment.getSourcePos(err.pos + err.body.length());
                        case IDENTIFIER:
                            DCIdentifier ident = (DCIdentifier) tree;

                            return dcComment.comment.getSourcePos(ident.pos + (ident.name != names.error ? ident.name.length() : 0));
                        case PARAM:
                            DCParam param = (DCParam) tree;

                            if (param.isTypeParameter && param.getDescription().isEmpty()) {
                                correction = 1;
                            }
                        case AUTHOR: case DEPRECATED: case RETURN: case SEE:
                        case SERIAL: case SERIAL_DATA: case SERIAL_FIELD: case SINCE:
                        case THROWS: case UNKNOWN_BLOCK_TAG: case VERSION: {
                            DocTree last = getLastChild(tree);

                            if (last != null) {
                                return getEndPosition(file, comment, last) + correction;
                            }

                            DCBlockTag block = (DCBlockTag) tree;

                            return dcComment.comment.getSourcePos(block.pos + block.getTagName().length() + 1);
                        }
                        default:
                            DocTree last = getLastChild(tree);

                            if (last != null) {
                                return getEndPosition(file, comment, last);
                            }
                            break;
                    }

                    return Position.NOPOS;
                }
            };
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public DocTreeMaker getDocTreeFactory() {
        return docTreeMaker;
    }

    private DocTree getLastChild(DocTree tree) {
        final DocTree[] last = new DocTree[] {null};

        tree.accept(new DocTreeScanner<Void, Void>() {
            @Override @DefinedBy(Api.COMPILER_TREE)
            public Void scan(DocTree node, Void p) {
                if (node != null) last[0] = node;
                return null;
            }
        }, null);

        return last[0];
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public JCClassDecl getTree(TypeElement element) {
        return (JCClassDecl) getTree((Element) element);
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public JCMethodDecl getTree(ExecutableElement method) {
        return (JCMethodDecl) getTree((Element) method);
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public JCTree getTree(Element element) {
        return getTree(element, null);
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public JCTree getTree(Element e, AnnotationMirror a) {
        return getTree(e, a, null);
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public JCTree getTree(Element e, AnnotationMirror a, AnnotationValue v) {
        Pair<JCTree, JCCompilationUnit> treeTopLevel = elements.getTreeAndTopLevel(e, a, v);
        if (treeTopLevel == null)
            return null;
        return treeTopLevel.fst;
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public TreePath getPath(CompilationUnitTree unit, Tree node) {
        return TreePath.getPath(unit, node);
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public TreePath getPath(Element e) {
        return getPath(e, null, null);
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public TreePath getPath(Element e, AnnotationMirror a) {
        return getPath(e, a, null);
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public TreePath getPath(Element e, AnnotationMirror a, AnnotationValue v) {
        final Pair<JCTree, JCCompilationUnit> treeTopLevel = elements.getTreeAndTopLevel(e, a, v);
        if (treeTopLevel == null)
            return null;
        return TreePath.getPath(treeTopLevel.snd, treeTopLevel.fst);
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public Symbol getElement(TreePath path) {
        JCTree tree = (JCTree) path.getLeaf();
        Symbol sym = TreeInfo.symbolFor(tree);
        if (sym == null) {
            for (TreePath p = path; p != null; p = p.getParentPath()) {
                JCTree t = (JCTree) p.getLeaf();
                if (t.hasTag(JCTree.Tag.CLASSDEF)) {
                    JCClassDecl ct = (JCClassDecl) t;
                    if (ct.sym != null) {
                        if ((ct.sym.flags_field & Flags.UNATTRIBUTED) != 0) {
                            attr.attribClass(ct.pos(), ct.sym);
                            sym = TreeInfo.symbolFor(tree);
                        }
                        break;
                    }
                }
            }
        }
        return sym;
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public Element getElement(DocTreePath path) {
        DocTree forTree = path.getLeaf();
        if (forTree instanceof DCReference)
            return attributeDocReference(path.getTreePath(), ((DCReference) forTree));
        if (forTree instanceof DCIdentifier) {
            if (path.getParentPath().getLeaf() instanceof DCParam) {
                return attributeParamIdentifier(path.getTreePath(), (DCParam) path.getParentPath().getLeaf());
            }
        }
        return null;
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public java.util.List<DocTree> getFirstSentence(java.util.List<? extends DocTree> list) {
        return docTreeMaker.getFirstSentence(list);
    }

    private Symbol attributeDocReference(TreePath path, DCReference ref) {
        Env<AttrContext> env = getAttrContext(path);
        if (env == null) return null;

        Log.DeferredDiagnosticHandler deferredDiagnosticHandler =
                new Log.DeferredDiagnosticHandler(log);
        try {
            final TypeSymbol tsym;
            final Name memberName;
            if (ref.qualifierExpression == null) {
                tsym = env.enclClass.sym;
                memberName = (Name) ref.memberName;
            } else {
                // newSeeTree if the qualifierExpression is a type or package name.
                // javac does not provide the exact method required, so
                // we first check if qualifierExpression identifies a type,
                // and if not, then we check to see if it identifies a package.
                Type t = attr.attribType(ref.qualifierExpression, env);
                if (t.isErroneous()) {
                    JCCompilationUnit toplevel =
                        treeMaker.TopLevel(List.nil());
                    final ModuleSymbol msym = modules.getDefaultModule();
                    toplevel.modle = msym;
                    toplevel.packge = msym.unnamedPackage;
                    Symbol sym = attr.attribIdent(ref.qualifierExpression, toplevel);

                    if (sym == null)
                        return null;

                    sym.complete();

                    if ((sym.kind == PCK || sym.kind == TYP) && sym.exists()) {
                        tsym = (TypeSymbol) sym;
                        memberName = (Name) ref.memberName;
                        if (sym.kind == PCK && memberName != null) {
                            //cannot refer to a package "member"
                            return null;
                        }
                    } else {
                        if (ref.qualifierExpression.hasTag(JCTree.Tag.IDENT)) {
                            // fixup:  allow "identifier" instead of "#identifier"
                            // for compatibility with javadoc
                            tsym = env.enclClass.sym;
                            memberName = ((JCIdent) ref.qualifierExpression).name;
                        } else {
                            return null;
                        }
                    }
                } else {
                    Type e = t;
                    // If this is an array type convert to element type
                    while (e instanceof ArrayType)
                        e = ((ArrayType)e).elemtype;
                    tsym = e.tsym;
                    memberName = (Name) ref.memberName;
                }
            }

            if (memberName == null)
                return tsym;

            final List<Type> paramTypes;
            if (ref.paramTypes == null)
                paramTypes = null;
            else {
                ListBuffer<Type> lb = new ListBuffer<>();
                for (List<JCTree> l = (List<JCTree>) ref.paramTypes; l.nonEmpty(); l = l.tail) {
                    JCTree tree = l.head;
                    Type t = attr.attribType(tree, env);
                    lb.add(t);
                }
                paramTypes = lb.toList();
            }

            ClassSymbol sym = (ClassSymbol) types.skipTypeVars(tsym.type, false).tsym;

            Symbol msym = (memberName == sym.name)
                    ? findConstructor(sym, paramTypes)
                    : findMethod(sym, memberName, paramTypes);
            if (paramTypes != null) {
                // explicit (possibly empty) arg list given, so cannot be a field
                return msym;
            }

            VarSymbol vsym = (ref.paramTypes != null) ? null : findField(sym, memberName);
            // prefer a field over a method with no parameters
            if (vsym != null &&
                    (msym == null ||
                        types.isSubtypeUnchecked(vsym.enclClass().asType(), msym.enclClass().asType()))) {
                return vsym;
            } else {
                return msym;
            }
        } catch (Abort e) { // may be thrown by Check.completionError in case of bad class file
            return null;
        } finally {
            log.popDiagnosticHandler(deferredDiagnosticHandler);
        }
    }

    private Symbol attributeParamIdentifier(TreePath path, DCParam ptag) {
        Symbol javadocSymbol = getElement(path);
        if (javadocSymbol == null)
            return null;
        ElementKind kind = javadocSymbol.getKind();
        List<? extends Symbol> params = List.nil();
        if (kind == ElementKind.METHOD || kind == ElementKind.CONSTRUCTOR) {
            MethodSymbol ee = (MethodSymbol) javadocSymbol;
            params = ptag.isTypeParameter()
                    ? ee.getTypeParameters()
                    : ee.getParameters();
        } else if (kind.isClass() || kind.isInterface()) {
            ClassSymbol te = (ClassSymbol) javadocSymbol;
            params = te.getTypeParameters();
        }

        for (Symbol param : params) {
            if (param.getSimpleName() == ptag.getName().getName()) {
                return param;
            }
        }
        return null;
    }

    
See Also:
findField.findField/** @see com.sun.tools.javadoc.ClassDocImpl#findField */
    private VarSymbol findField(ClassSymbol tsym, Name fieldName) {
        return searchField(tsym, fieldName, new HashSet<>());
    }

    
See Also:
searchField.searchField/** @see com.sun.tools.javadoc.ClassDocImpl#searchField */
    private VarSymbol searchField(ClassSymbol tsym, Name fieldName, Set<ClassSymbol> searched) {
        if (searched.contains(tsym)) {
            return null;
        }
        searched.add(tsym);

        for (Symbol sym : tsym.members().getSymbolsByName(fieldName)) {
            if (sym.kind == VAR) {
                return (VarSymbol)sym;
            }
        }

        //### If we found a VarSymbol above, but which did not pass
        //### the modifier filter, we should return failure here!

        ClassSymbol encl = tsym.owner.enclClass();
        if (encl != null) {
            VarSymbol vsym = searchField(encl, fieldName, searched);
            if (vsym != null) {
                return vsym;
            }
        }

        // search superclass
        Type superclass = tsym.getSuperclass();
        if (superclass.tsym != null) {
            VarSymbol vsym = searchField((ClassSymbol) superclass.tsym, fieldName, searched);
            if (vsym != null) {
                return vsym;
            }
        }

        // search interfaces
        List<Type> intfs = tsym.getInterfaces();
        for (List<Type> l = intfs; l.nonEmpty(); l = l.tail) {
            Type intf = l.head;
            if (intf.isErroneous()) continue;
            VarSymbol vsym = searchField((ClassSymbol) intf.tsym, fieldName, searched);
            if (vsym != null) {
                return vsym;
            }
        }

        return null;
    }

    
See Also:
findConstructor.findConstructor/** @see com.sun.tools.javadoc.ClassDocImpl#findConstructor */
    MethodSymbol findConstructor(ClassSymbol tsym, List<Type> paramTypes) {
        for (Symbol sym : tsym.members().getSymbolsByName(names.init)) {
            if (sym.kind == MTH) {
                if (hasParameterTypes((MethodSymbol) sym, paramTypes)) {
                    return (MethodSymbol) sym;
                }
            }
        }
        return null;
    }

    
See Also:
findMethod.findMethod/** @see com.sun.tools.javadoc.ClassDocImpl#findMethod */
    private MethodSymbol findMethod(ClassSymbol tsym, Name methodName, List<Type> paramTypes) {
        return searchMethod(tsym, methodName, paramTypes, new HashSet<>());
    }

    
See Also:
searchMethod.searchMethod/** @see com.sun.tools.javadoc.ClassDocImpl#searchMethod */
    private MethodSymbol searchMethod(ClassSymbol tsym, Name methodName,
                                       List<Type> paramTypes, Set<ClassSymbol> searched) {
        //### Note that this search is not necessarily what the compiler would do!

        // do not match constructors
        if (methodName == names.init)
            return null;

        if (searched.contains(tsym))
            return null;
        searched.add(tsym);

        // search current class

        //### Using modifier filter here isn't really correct,
        //### but emulates the old behavior.  Instead, we should
        //### apply the normal rules of visibility and inheritance.

        if (paramTypes == null) {
            // If no parameters specified, we are allowed to return
            // any method with a matching name.  In practice, the old
            // code returned the first method, which is now the last!
            // In order to provide textually identical results, we
            // attempt to emulate the old behavior.
            MethodSymbol lastFound = null;
            for (Symbol sym : tsym.members().getSymbolsByName(methodName)) {
                if (sym.kind == MTH) {
                    if (sym.name == methodName) {
                        lastFound = (MethodSymbol)sym;
                    }
                }
            }
            if (lastFound != null) {
                return lastFound;
            }
        } else {
            for (Symbol sym : tsym.members().getSymbolsByName(methodName)) {
                if (sym != null &&
                    sym.kind == MTH) {
                    if (hasParameterTypes((MethodSymbol) sym, paramTypes)) {
                        return (MethodSymbol) sym;
                    }
                }
            }
        }

        //### If we found a MethodSymbol above, but which did not pass
        //### the modifier filter, we should return failure here!

        // search superclass
        Type superclass = tsym.getSuperclass();
        if (superclass.tsym != null) {
            MethodSymbol msym = searchMethod((ClassSymbol) superclass.tsym, methodName, paramTypes, searched);
            if (msym != null) {
                return msym;
            }
        }

        // search interfaces
        List<Type> intfs = tsym.getInterfaces();
        for (List<Type> l = intfs; l.nonEmpty(); l = l.tail) {
            Type intf = l.head;
            if (intf.isErroneous()) continue;
            MethodSymbol msym = searchMethod((ClassSymbol) intf.tsym, methodName, paramTypes, searched);
            if (msym != null) {
                return msym;
            }
        }

        // search enclosing class
        ClassSymbol encl = tsym.owner.enclClass();
        if (encl != null) {
            MethodSymbol msym = searchMethod(encl, methodName, paramTypes, searched);
            if (msym != null) {
                return msym;
            }
        }

        return null;
    }

    
See Also:
ClassDocImpl/** @see com.sun.tools.javadoc.ClassDocImpl */
    private boolean hasParameterTypes(MethodSymbol method, List<Type> paramTypes) {
        if (paramTypes == null)
            return true;

        if (method.params().size() != paramTypes.size())
            return false;

        List<Type> methodParamTypes = types.erasureRecursive(method.asType()).getParameterTypes();

        return (Type.isErroneous(paramTypes))
            ? fuzzyMatch(paramTypes, methodParamTypes)
            : types.isSameTypes(paramTypes, methodParamTypes);
    }

    boolean fuzzyMatch(List<Type> paramTypes, List<Type> methodParamTypes) {
        List<Type> l1 = paramTypes;
        List<Type> l2 = methodParamTypes;
        while (l1.nonEmpty()) {
            if (!fuzzyMatch(l1.head, l2.head))
                return false;
            l1 = l1.tail;
            l2 = l2.tail;
        }
        return true;
    }

    boolean fuzzyMatch(Type paramType, Type methodParamType) {
        Boolean b = fuzzyMatcher.visit(paramType, methodParamType);
        return (b == Boolean.TRUE);
    }

    TypeRelation fuzzyMatcher = new TypeRelation() {
        @Override
        public Boolean visitType(Type t, Type s) {
            if (t == s)
                return true;

            if (s.isPartial())
                return visit(s, t);

            switch (t.getTag()) {
            case BYTE: case CHAR: case SHORT: case INT: case LONG: case FLOAT:
            case DOUBLE: case BOOLEAN: case VOID: case BOT: case NONE:
                return t.hasTag(s.getTag());
            default:
                throw new AssertionError("fuzzyMatcher " + t.getTag());
            }
        }

        @Override
        public Boolean visitArrayType(ArrayType t, Type s) {
            if (t == s)
                return true;

            if (s.isPartial())
                return visit(s, t);

            return s.hasTag(ARRAY)
                && visit(t.elemtype, types.elemtype(s));
        }

        @Override
        public Boolean visitClassType(ClassType t, Type s) {
            if (t == s)
                return true;

            if (s.isPartial())
                return visit(s, t);

            return t.tsym == s.tsym;
        }

        @Override
        public Boolean visitErrorType(ErrorType t, Type s) {
            return s.hasTag(CLASS)
                    && t.tsym.name == ((ClassType) s).tsym.name;
        }
    };

    @Override @DefinedBy(Api.COMPILER_TREE)
    public TypeMirror getTypeMirror(TreePath path) {
        Tree t = path.getLeaf();
        Type ty = ((JCTree)t).type;
        return ty == null ? null : ty.stripMetadataIfNeeded();
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public JavacScope getScope(TreePath path) {
        return JavacScope.create(getAttrContext(path));
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public String getDocComment(TreePath path) {
        CompilationUnitTree t = path.getCompilationUnit();
        Tree leaf = path.getLeaf();
        if (t instanceof JCTree.JCCompilationUnit && leaf instanceof JCTree) {
            JCCompilationUnit cu = (JCCompilationUnit) t;
            if (cu.docComments != null) {
                return cu.docComments.getCommentText((JCTree) leaf);
            }
        }
        return null;
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public DocCommentTree getDocCommentTree(TreePath path) {
        CompilationUnitTree t = path.getCompilationUnit();
        Tree leaf = path.getLeaf();
        if (t instanceof JCTree.JCCompilationUnit && leaf instanceof JCTree) {
            JCCompilationUnit cu = (JCCompilationUnit) t;
            if (cu.docComments != null) {
                return cu.docComments.getCommentTree((JCTree) leaf);
            }
        }
        return null;
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public DocCommentTree getDocCommentTree(Element e) {
        TreePath path = getPath(e);
        if (path == null) {
            return null;
        }
        return getDocCommentTree(path);
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public DocCommentTree getDocCommentTree(Element e, String relativeFileName) throws IOException {
        PackageElement pkg = elements.getPackageOf(e);
        FileObject fileForInput = fileManager.getFileForInput(StandardLocation.SOURCE_PATH,
                pkg.getQualifiedName().toString(), relativeFileName);

        if (fileForInput == null) {
            throw new FileNotFoundException(relativeFileName);
        }
        return getDocCommentTree(fileForInput);
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public boolean isAccessible(Scope scope, TypeElement type) {
        if (scope instanceof JavacScope && type instanceof ClassSymbol) {
            Env<AttrContext> env = ((JavacScope) scope).env;
            return resolve.isAccessible(env, (ClassSymbol)type, true);
        } else
            return false;
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public boolean isAccessible(Scope scope, Element member, DeclaredType type) {
        if (scope instanceof JavacScope
                && member instanceof Symbol
                && type instanceof com.sun.tools.javac.code.Type) {
            Env<AttrContext> env = ((JavacScope) scope).env;
            return resolve.isAccessible(env, (com.sun.tools.javac.code.Type)type, (Symbol)member, true);
        } else
            return false;
    }

    private Env<AttrContext> getAttrContext(TreePath path) {
        if (!(path.getLeaf() instanceof JCTree))  // implicit null-check
            throw new IllegalArgumentException();

        // if we're being invoked from a Tree API client via parse/enter/analyze,
        // we need to make sure all the classes have been entered;
        // if we're being invoked from JSR 199 or JSR 269, then the classes
        // will already have been entered.
        if (javacTaskImpl != null) {
            javacTaskImpl.enter(null);
        }

        JCCompilationUnit unit = (JCCompilationUnit) path.getCompilationUnit();
        Copier copier = createCopier(treeMaker.forToplevel(unit));

        Env<AttrContext> env = null;
        JCMethodDecl method = null;
        JCVariableDecl field = null;

        List<Tree> l = List.nil();
        TreePath p = path;
        while (p != null) {
            l = l.prepend(p.getLeaf());
            p = p.getParentPath();
        }

        for ( ; l.nonEmpty(); l = l.tail) {
            Tree tree = l.head;
            switch (tree.getKind()) {
                case COMPILATION_UNIT:
//                    System.err.println("COMP: " + ((JCCompilationUnit)tree).sourcefile);
                    env = enter.getTopLevelEnv((JCCompilationUnit)tree);
                    break;
                case ANNOTATION_TYPE:
                case CLASS:
                case ENUM:
                case INTERFACE:
//                    System.err.println("CLASS: " + ((JCClassDecl)tree).sym.getSimpleName());
                    env = enter.getClassEnv(((JCClassDecl)tree).sym);
                    if (env == null) return null;
                    break;
                case METHOD:
//                    System.err.println("METHOD: " + ((JCMethodDecl)tree).sym.getSimpleName());
                    method = (JCMethodDecl)tree;
                    env = memberEnter.getMethodEnv(method, env);
                    break;
                case VARIABLE:
//                    System.err.println("FIELD: " + ((JCVariableDecl)tree).sym.getSimpleName());
                    field = (JCVariableDecl)tree;
                    break;
                case BLOCK: {
//                    System.err.println("BLOCK: ");
                    if (method != null) {
                        try {
                            Assert.check(method.body == tree);
                            method.body = copier.copy((JCBlock)tree, (JCTree) path.getLeaf());
                            env = attribStatToTree(method.body, env, copier.leafCopy);
                        } finally {
                            method.body = (JCBlock) tree;
                        }
                    } else {
                        JCBlock body = copier.copy((JCBlock)tree, (JCTree) path.getLeaf());
                        env = attribStatToTree(body, env, copier.leafCopy);
                    }
                    return env;
                }
                default:
//                    System.err.println("DEFAULT: " + tree.getKind());
                    if (field != null && field.getInitializer() == tree) {
                        env = memberEnter.getInitEnv(field, env);
                        JCExpression expr = copier.copy((JCExpression)tree, (JCTree) path.getLeaf());
                        env = attribExprToTree(expr, env, copier.leafCopy);
                        return env;
                    }
            }
        }
        return (field != null) ? memberEnter.getInitEnv(field, env) : env;
    }

    private Env<AttrContext> attribStatToTree(JCTree stat, Env<AttrContext>env, JCTree tree) {
        JavaFileObject prev = log.useSource(env.toplevel.sourcefile);
        try {
            return attr.attribStatToTree(stat, env, tree);
        } finally {
            log.useSource(prev);
        }
    }

    private Env<AttrContext> attribExprToTree(JCExpression expr, Env<AttrContext>env, JCTree tree) {
        JavaFileObject prev = log.useSource(env.toplevel.sourcefile);
        try {
            return attr.attribExprToTree(expr, env, tree);
        } finally {
            log.useSource(prev);
        }
    }

    static JavaFileObject asJavaFileObject(FileObject fileObject) {
        JavaFileObject jfo = null;

        if (fileObject instanceof JavaFileObject) {
            jfo = (JavaFileObject) fileObject;
            checkHtmlKind(fileObject, Kind.HTML);
            return jfo;
        }

        checkHtmlKind(fileObject);
        jfo = new HtmlFileObject(fileObject);
        return jfo;
    }

    private static void checkHtmlKind(FileObject fileObject) {
        checkHtmlKind(fileObject, BaseFileManager.getKind(fileObject.getName()));
    }

    private static void checkHtmlKind(FileObject fileObject, JavaFileObject.Kind kind) {
        if (kind != JavaFileObject.Kind.HTML) {
            throw new IllegalArgumentException("HTML file expected:" + fileObject.getName());
        }
    }

    private static class HtmlFileObject extends ForwardingFileObject<FileObject>
            implements JavaFileObject {

        public HtmlFileObject(FileObject fileObject) {
            super(fileObject);
        }

        @Override @DefinedBy(Api.COMPILER)
        public Kind getKind() {
            return BaseFileManager.getKind(fileObject.getName());
        }

        @Override @DefinedBy(Api.COMPILER)
        public boolean isNameCompatible(String simpleName, Kind kind) {
            return false;
        }

        @Override @DefinedBy(Api.COMPILER)
        public NestingKind getNestingKind() {
            return null;
        }

        @Override @DefinedBy(Api.COMPILER)
        public Modifier getAccessLevel() {
            return null;
        }
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public DocCommentTree getDocCommentTree(FileObject fileObject) {
        JavaFileObject jfo = asJavaFileObject(fileObject);
        DiagnosticSource diagSource = new DiagnosticSource(jfo, log);

        final Comment comment = new Comment() {
            int offset = 0;
            @Override
            public String getText() {
                try {
                    CharSequence rawDoc = fileObject.getCharContent(true);
                    return rawDoc.toString();
                } catch (IOException ignore) {
                    // do nothing
                }
                return "";
            }

            @Override
            public int getSourcePos(int index) {
                return offset + index;
            }

            @Override
            public CommentStyle getStyle() {
                throw new UnsupportedOperationException();
            }

            @Override
            public boolean isDeprecated() {
                throw new UnsupportedOperationException();
            }
        };

        return new DocCommentParser(parser, diagSource, comment, true).parse();
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public DocTreePath getDocTreePath(FileObject fileObject, PackageElement packageElement) {
        JavaFileObject jfo = asJavaFileObject(fileObject);
        DocCommentTree docCommentTree = getDocCommentTree(jfo);
        if (docCommentTree == null)
            return null;
        TreePath treePath = makeTreePath((PackageSymbol)packageElement, jfo, docCommentTree);
        return new DocTreePath(treePath, docCommentTree);
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public void setBreakIterator(BreakIterator breakiterator) {
        this.breakIterator = breakiterator;
    }

    
Makes a copy of a tree, noting the value resulting from copying a particular leaf.
/**
     * Makes a copy of a tree, noting the value resulting from copying a particular leaf.
     **/
    protected static class Copier extends TreeCopier<JCTree> {
        JCTree leafCopy = null;

        protected Copier(TreeMaker M) {
            super(M);
        }

        @Override
        public <T extends JCTree> T copy(T t, JCTree leaf) {
            T t2 = super.copy(t, leaf);
            if (t == leaf)
                leafCopy = t2;
            return t2;
        }
    }

    protected Copier createCopier(TreeMaker maker) {
        return new Copier(maker);
    }

    
Returns the original type from the ErrorType object.
Params:
errorType – The errorType for which we want to get the original type.
Returns:
TypeMirror corresponding to the original type, replaced by the ErrorType.
        noType (type.tag == NONE) is returned if there is no original type./**
     * Returns the original type from the ErrorType object.
     * @param errorType The errorType for which we want to get the original type.
     * @return TypeMirror corresponding to the original type, replaced by the ErrorType.
     *         noType (type.tag == NONE) is returned if there is no original type.
     */
    @Override @DefinedBy(Api.COMPILER_TREE)
    public TypeMirror getOriginalType(javax.lang.model.type.ErrorType errorType) {
        if (errorType instanceof com.sun.tools.javac.code.Type.ErrorType) {
            return ((com.sun.tools.javac.code.Type.ErrorType)errorType).getOriginalType();
        }
        if (errorType instanceof com.sun.tools.javac.code.Type.ClassType &&
            errorType.getKind() == TypeKind.ERROR) {
            ClassType ct = (ClassType) errorType;
            return extraType2OriginalMap.computeIfAbsent(ct, tt ->
                    new ClassType(ct.getEnclosingType(), ct.typarams_field,
                                  ct.tsym, ct.getMetadata()) {
                        @Override
                        public Type baseType() { return ct; }
                        @Override
                        public TypeKind getKind() {
                            return TypeKind.DECLARED;
                        }
                    });
        }

        return com.sun.tools.javac.code.Type.noType;
    }

    
Prints a message of the specified kind at the location of the
tree within the provided compilation unit
Params:
kind – the kind of message
msg –  the message, or an empty string if none
t –    the tree to use as a position hint
root – the compilation unit that contains tree/**
     * Prints a message of the specified kind at the location of the
     * tree within the provided compilation unit
     *
     * @param kind the kind of message
     * @param msg  the message, or an empty string if none
     * @param t    the tree to use as a position hint
     * @param root the compilation unit that contains tree
     */
    @Override @DefinedBy(Api.COMPILER_TREE)
    public void printMessage(Diagnostic.Kind kind, CharSequence msg,
            com.sun.source.tree.Tree t,
            com.sun.source.tree.CompilationUnitTree root) {
        printMessage(kind, msg, ((JCTree) t).pos(), root);
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public void printMessage(Diagnostic.Kind kind, CharSequence msg,
            com.sun.source.doctree.DocTree t,
            com.sun.source.doctree.DocCommentTree c,
            com.sun.source.tree.CompilationUnitTree root) {
        printMessage(kind, msg, ((DCTree) t).pos((DCDocComment) c), root);
    }

    private void printMessage(Diagnostic.Kind kind, CharSequence msg,
            JCDiagnostic.DiagnosticPosition pos,
            com.sun.source.tree.CompilationUnitTree root) {
        JavaFileObject oldSource = null;
        JavaFileObject newSource = null;

        newSource = root.getSourceFile();
        if (newSource == null) {
            pos = null;
        } else {
            oldSource = log.useSource(newSource);
        }

        try {
            switch (kind) {
            case ERROR:
                log.error(DiagnosticFlag.API, pos, Errors.ProcMessager(msg.toString()));
                break;

            case WARNING:
                log.warning(pos, Warnings.ProcMessager(msg.toString()));
                break;

            case MANDATORY_WARNING:
                log.mandatoryWarning(pos, Warnings.ProcMessager(msg.toString()));
                break;

            default:
                log.note(pos, Notes.ProcMessager(msg.toString()));
            }
        } finally {
            if (oldSource != null)
                log.useSource(oldSource);
        }
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public TypeMirror getLub(CatchTree tree) {
        JCCatch ct = (JCCatch) tree;
        JCVariableDecl v = ct.param;
        if (v.type != null && v.type.getKind() == TypeKind.UNION) {
            UnionClassType ut = (UnionClassType) v.type;
            return ut.getLub();
        } else {
            return v.type;
        }
    }

    private TreePath makeTreePath(final PackageSymbol psym, final JavaFileObject jfo,
            DocCommentTree dcTree) {
        JCCompilationUnit jcCompilationUnit = new JCCompilationUnit(List.nil()) {
            public int getPos() {
                return Position.FIRSTPOS;
            }

            public JavaFileObject getSourcefile() {
                return jfo;
            }

            @Override @DefinedBy(Api.COMPILER_TREE)
            public Position.LineMap getLineMap() {
                try {
                    CharSequence content = jfo.getCharContent(true);
                    String s = content.toString();
                    return Position.makeLineMap(s.toCharArray(), s.length(), true);
                } catch (IOException ignore) {}
                return null;
            }
        };

        jcCompilationUnit.docComments = new DocCommentTable() {
            @Override
            public boolean hasComment(JCTree tree) {
                return false;
            }

            @Override
            public Comment getComment(JCTree tree) {
                throw new UnsupportedOperationException();
            }

            @Override
            public String getCommentText(JCTree tree) {
                throw new UnsupportedOperationException();
            }

            @Override
            public DCDocComment getCommentTree(JCTree tree) {
                return (DCDocComment)dcTree;
            }

            @Override
            public void putComment(JCTree tree, Comment c) {
                throw new UnsupportedOperationException();
            }

        };
        jcCompilationUnit.lineMap = jcCompilationUnit.getLineMap();
        jcCompilationUnit.modle = psym.modle;
        jcCompilationUnit.sourcefile = jfo;
        jcCompilationUnit.namedImportScope = new NamedImportScope(psym);
        jcCompilationUnit.packge = psym;
        jcCompilationUnit.starImportScope = new StarImportScope(psym);
        jcCompilationUnit.toplevelScope = WriteableScope.create(psym);
        return new TreePath(jcCompilationUnit);
    }
}