/*

 * Copyright (c) 1999, 2014, 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.comp;

import java.util.*;

import javax.tools.JavaFileObject;

import javax.tools.JavaFileManager;

import com.sun.tools.javac.code.*;

import com.sun.tools.javac.code.Scope.*;

import com.sun.tools.javac.code.Symbol.*;

import com.sun.tools.javac.code.Type.*;

import com.sun.tools.javac.jvm.*;

import com.sun.tools.javac.main.Option.PkgInfo;

import com.sun.tools.javac.tree.*;

import com.sun.tools.javac.tree.JCTree.*;

import com.sun.tools.javac.util.*;

import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;

import com.sun.tools.javac.util.List;

import static com.sun.tools.javac.code.Flags.*;

/** This class enters symbols for all encountered definitions into

 *  the symbol table. The pass consists of two phases, organized as

 *  follows:

 *

 *  <p>In the first phase, all class symbols are entered into their

 *  enclosing scope, descending recursively down the tree for classes

 *  which are members of other classes. The class symbols are given a

 *  MemberEnter object as completer.

 *

 *  <p>In the second phase classes are completed using

 *  MemberEnter.complete().  Completion might occur on demand, but

 *  any classes that are not completed that way will be eventually

 *  completed by processing the `uncompleted' queue.  Completion

 *  entails (1) determination of a class's parameters, supertype and

 *  interfaces, as well as (2) entering all symbols defined in the

 *  class into its scope, with the exception of class symbols which

 *  have been entered in phase 1.  (2) depends on (1) having been

 *  completed for a class and all its superclasses and enclosing

 *  classes. That's why, after doing (1), we put classes in a

 *  `halfcompleted' queue. Only when we have performed (1) for a class

 *  and all it's superclasses and enclosing classes, we proceed to

 *  (2).

 *

 *  <p>Whereas the first phase is organized as a sweep through all

 *  compiled syntax trees, the second phase is demand. Members of a

 *  class are entered when the contents of a class are first

 *  accessed. This is accomplished by installing completer objects in

 *  class symbols for compiled classes which invoke the member-enter

 *  phase for the corresponding class tree.

 *

 *  <p>Classes migrate from one phase to the next via queues:

 *

 *  <pre>{@literal

 *  class enter -> (Enter.uncompleted)         --> member enter (1)

 *              -> (MemberEnter.halfcompleted) --> member enter (2)

 *              -> (Todo)                      --> attribute

 *                                              (only for toplevel classes)

 *  }</pre>

 *

 *  <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 Enter extends JCTree.Visitor {

    protected static final Context.Key<Enter> enterKey = new Context.Key<>();

    Log log;

    Symtab syms;

    Check chk;

    TreeMaker make;

    Annotate annotate;

    MemberEnter memberEnter;

    Types types;

    Lint lint;

    Names names;

    JavaFileManager fileManager;

    PkgInfo pkginfoOpt;

    TypeEnvs typeEnvs;

    private final Todo todo;

    public static Enter instance(Context context) {

        Enter instance = context.get(enterKey);

        if (instance == null)

            instance = new Enter(context);

        return instance;

    }

    protected Enter(Context context) {

        context.put(enterKey, this);

        log = Log.instance(context);

        make = TreeMaker.instance(context);

        syms = Symtab.instance(context);

        chk = Check.instance(context);

        memberEnter = MemberEnter.instance(context);

        types = Types.instance(context);

        annotate = Annotate.instance(context);

        lint = Lint.instance(context);

        names = Names.instance(context);

        predefClassDef = make.ClassDef(

            make.Modifiers(PUBLIC),

            syms.predefClass.name,

            List.<JCTypeParameter>nil(),

            null,

            List.<JCExpression>nil(),

            List.<JCTree>nil());

        predefClassDef.sym = syms.predefClass;

        todo = Todo.instance(context);

        fileManager = context.get(JavaFileManager.class);

        Options options = Options.instance(context);

        pkginfoOpt = PkgInfo.get(options);

        typeEnvs = TypeEnvs.instance(context);

    }

    /** Accessor for typeEnvs

     */

    public Env<AttrContext> getEnv(TypeSymbol sym) {

        return typeEnvs.get(sym);

    }

    public Iterable<Env<AttrContext>> getEnvs() {

        return typeEnvs.values();

    }

    public Env<AttrContext> getClassEnv(TypeSymbol sym) {

        Env<AttrContext> localEnv = getEnv(sym);

        Env<AttrContext> lintEnv = localEnv;

        while (lintEnv.info.lint == null)

            lintEnv = lintEnv.next;

        localEnv.info.lint = lintEnv.info.lint.augment(sym);

        return localEnv;

    }

    /** The queue of all classes that might still need to be completed;

     *  saved and initialized by main().

     */

    ListBuffer<ClassSymbol> uncompleted;

    /** A dummy class to serve as enclClass for toplevel environments.

     */

    private JCClassDecl predefClassDef;

/* ************************************************************************

 * environment construction

 *************************************************************************/

    /** Create a fresh environment for class bodies.

     *  This will create a fresh scope for local symbols of a class, referred

     *  to by the environments info.scope field.

     *  This scope will contain

     *    - symbols for this and super

     *    - symbols for any type parameters

     *  In addition, it serves as an anchor for scopes of methods and initializers

     *  which are nested in this scope via Scope.dup().

     *  This scope should not be confused with the members scope of a class.

     *

     *  @param tree     The class definition.

     *  @param env      The environment current outside of the class definition.

     */

    public Env<AttrContext> classEnv(JCClassDecl tree, Env<AttrContext> env) {

        Env<AttrContext> localEnv =

            env.dup(tree, env.info.dup(WriteableScope.create(tree.sym)));

        localEnv.enclClass = tree;

        localEnv.outer = env;

        localEnv.info.isSelfCall = false;

        localEnv.info.lint = null; // leave this to be filled in by Attr,

                                   // when annotations have been processed

        return localEnv;

    }

    /** Create a fresh environment for toplevels.

     *  @param tree     The toplevel tree.

     */

    Env<AttrContext> topLevelEnv(JCCompilationUnit tree) {

        Env<AttrContext> localEnv = new Env<>(tree, new AttrContext());

        localEnv.toplevel = tree;

        localEnv.enclClass = predefClassDef;

        tree.toplevelScope = WriteableScope.create(tree.packge);

        tree.namedImportScope = new NamedImportScope(tree.packge, tree.toplevelScope);

        tree.starImportScope = new StarImportScope(tree.packge);

        localEnv.info.scope = tree.toplevelScope;

        localEnv.info.lint = lint;

        return localEnv;

    }

    public Env<AttrContext> getTopLevelEnv(JCCompilationUnit tree) {

        Env<AttrContext> localEnv = new Env<>(tree, new AttrContext());

        localEnv.toplevel = tree;

        localEnv.enclClass = predefClassDef;

        localEnv.info.scope = tree.toplevelScope;

        localEnv.info.lint = lint;

        return localEnv;

    }

    /** The scope in which a member definition in environment env is to be entered

     *  This is usually the environment's scope, except for class environments,

     *  where the local scope is for type variables, and the this and super symbol

     *  only, and members go into the class member scope.

     */

    WriteableScope enterScope(Env<AttrContext> env) {

        return (env.tree.hasTag(JCTree.Tag.CLASSDEF))

            ? ((JCClassDecl) env.tree).sym.members_field

            : env.info.scope;

    }

/* ************************************************************************

 * Visitor methods for phase 1: class enter

 *************************************************************************/

    /** Visitor argument: the current environment.

     */

    protected Env<AttrContext> env;

    /** Visitor result: the computed type.

     */

    Type result;

    /** Visitor method: enter all classes in given tree, catching any

     *  completion failure exceptions. Return the tree's type.

     *

     *  @param tree    The tree to be visited.

     *  @param env     The environment visitor argument.

     */

    Type classEnter(JCTree tree, Env<AttrContext> env) {

        Env<AttrContext> prevEnv = this.env;

        try {

            this.env = env;

            tree.accept(this);

            return result;

        }  catch (CompletionFailure ex) {

            return chk.completionError(tree.pos(), ex);

        } finally {

            this.env = prevEnv;

        }

    }

    /** Visitor method: enter classes of a list of trees, returning a list of types.

     */

    <T extends JCTree> List<Type> classEnter(List<T> trees, Env<AttrContext> env) {

        ListBuffer<Type> ts = new ListBuffer<>();

        for (List<T> l = trees; l.nonEmpty(); l = l.tail) {

            Type t = classEnter(l.head, env);

            if (t != null)

                ts.append(t);

        }

        return ts.toList();

    }

    @Override

    public void visitTopLevel(JCCompilationUnit tree) {

        JavaFileObject prev = log.useSource(tree.sourcefile);

        boolean addEnv = false;

        boolean isPkgInfo = tree.sourcefile.isNameCompatible("package-info",

                                                             JavaFileObject.Kind.SOURCE);

        JCPackageDecl pd = tree.getPackage();

        if (pd != null) {

            tree.packge = pd.packge = syms.enterPackage(TreeInfo.fullName(pd.pid));

            if (   pd.annotations.nonEmpty()

                || pkginfoOpt == PkgInfo.ALWAYS

                || tree.docComments != null) {

                if (isPkgInfo) {

                    addEnv = true;

                } else if (pd.annotations.nonEmpty()) {

                    log.error(pd.annotations.head.pos(),

                              "pkg.annotations.sb.in.package-info.java");

                }

            }

        } else {

            tree.packge = syms.unnamedPackage;

        }

        tree.packge.complete(); // Find all classes in package.

        Env<AttrContext> topEnv = topLevelEnv(tree);

        Env<AttrContext> packageEnv = isPkgInfo ? topEnv.dup(pd) : null;

        // Save environment of package-info.java file.

        if (isPkgInfo) {

            Env<AttrContext> env0 = typeEnvs.get(tree.packge);

            if (env0 != null) {

                JCCompilationUnit tree0 = env0.toplevel;

                if (!fileManager.isSameFile(tree.sourcefile, tree0.sourcefile)) {

                    log.warning(pd != null ? pd.pid.pos() : null,

                                "pkg-info.already.seen",

                                tree.packge);

                }

            }

            typeEnvs.put(tree.packge, packageEnv);

            for (Symbol q = tree.packge; q != null && q.kind == PCK; q = q.owner)

                q.flags_field |= EXISTS;

            Name name = names.package_info;

            ClassSymbol c = syms.enterClass(name, tree.packge);

            c.flatname = names.fromString(tree.packge + "." + name);

            c.sourcefile = tree.sourcefile;

            c.completer = null;

            c.members_field = WriteableScope.create(c);

            tree.packge.package_info = c;

        }

        classEnter(tree.defs, topEnv);

        if (addEnv) {

            todo.append(packageEnv);

        }

        log.useSource(prev);

        result = null;

    }

    @Override

    public void visitClassDef(JCClassDecl tree) {

        Symbol owner = env.info.scope.owner;

        WriteableScope enclScope = enterScope(env);

        ClassSymbol c;

        if (owner.kind == PCK) {

            // We are seeing a toplevel class.

            PackageSymbol packge = (PackageSymbol)owner;

            for (Symbol q = packge; q != null && q.kind == PCK; q = q.owner)

                q.flags_field |= EXISTS;

            c = syms.enterClass(tree.name, packge);

            packge.members().enterIfAbsent(c);

            if ((tree.mods.flags & PUBLIC) != 0 && !classNameMatchesFileName(c, env)) {

                log.error(tree.pos(),

                          "class.public.should.be.in.file", tree.name);

            }

        } else {

            if (!tree.name.isEmpty() &&

                !chk.checkUniqueClassName(tree.pos(), tree.name, enclScope)) {

                result = null;

                return;

            }

            if (owner.kind == TYP) {

                // We are seeing a member class.

                c = syms.enterClass(tree.name, (TypeSymbol)owner);

                if ((owner.flags_field & INTERFACE) != 0) {

                    tree.mods.flags |= PUBLIC | STATIC;

                }

            } else {

                // We are seeing a local class.

                c = syms.defineClass(tree.name, owner);

                c.flatname = chk.localClassName(c);

                if (!c.name.isEmpty())

                    chk.checkTransparentClass(tree.pos(), c, env.info.scope);

            }

        }

        tree.sym = c;

        // Enter class into `compiled' table and enclosing scope.

        if (chk.compiled.get(c.flatname) != null) {

            duplicateClass(tree.pos(), c);

            result = types.createErrorType(tree.name, (TypeSymbol)owner, Type.noType);

            tree.sym = (ClassSymbol)result.tsym;

            return;

        }

        chk.compiled.put(c.flatname, c);

        enclScope.enter(c);

        // Set up an environment for class block and store in `typeEnvs'

        // table, to be retrieved later in memberEnter and attribution.

        Env<AttrContext> localEnv = classEnv(tree, env);

        typeEnvs.put(c, localEnv);

        // Fill out class fields.

        c.completer = memberEnter;

        c.flags_field = chk.checkFlags(tree.pos(), tree.mods.flags, c, tree);

        c.sourcefile = env.toplevel.sourcefile;

        c.members_field = WriteableScope.create(c);

        ClassType ct = (ClassType)c.type;

        if (owner.kind != PCK && (c.flags_field & STATIC) == 0) {

            // We are seeing a local or inner class.

            // Set outer_field of this class to closest enclosing class

            // which contains this class in a non-static context

            // (its "enclosing instance class"), provided such a class exists.

            Symbol owner1 = owner;

                   (owner1.flags_field & STATIC) == 0) {

                owner1 = owner1.owner;

            }

            if (owner1.kind == TYP) {

                ct.setEnclosingType(owner1.type);

            }

        }

        // Enter type parameters.

        ct.typarams_field = classEnter(tree.typarams, localEnv);

        // Add non-local class to uncompleted, to make sure it will be

        // completed later.

        if (!c.isLocal() && uncompleted != null) uncompleted.append(c);

//      System.err.println("entering " + c.fullname + " in " + c.owner);//DEBUG

        // Recursively enter all member classes.

        classEnter(tree.defs, localEnv);

        result = c.type;

    }

    //where

        /** Does class have the same name as the file it appears in?

         */

        private static boolean classNameMatchesFileName(ClassSymbol c,

                                                        Env<AttrContext> env) {

            return env.toplevel.sourcefile.isNameCompatible(c.name.toString(),

                                                            JavaFileObject.Kind.SOURCE);

        }

    /** Complain about a duplicate class. */

    protected void duplicateClass(DiagnosticPosition pos, ClassSymbol c) {

        log.error(pos, "duplicate.class", c.fullname);

    }

    /** Class enter visitor method for type parameters.

     *  Enter a symbol for type parameter in local scope, after checking that it

     *  is unique.

     */

    @Override

    public void visitTypeParameter(JCTypeParameter tree) {

        TypeVar a = (tree.type != null)

            ? (TypeVar)tree.type

            : new TypeVar(tree.name, env.info.scope.owner, syms.botType);

        tree.type = a;

        if (chk.checkUnique(tree.pos(), a.tsym, env.info.scope)) {

            env.info.scope.enter(a.tsym);

        }

        result = a;

    }

    /** Default class enter visitor method: do nothing.

     */

    @Override

    public void visitTree(JCTree tree) {

        result = null;

    }

    /** Main method: enter all classes in a list of toplevel trees.

     *  @param trees      The list of trees to be processed.

     */

    public void main(List<JCCompilationUnit> trees) {

        complete(trees, null);

    }

    /** Main method: enter one class from a list of toplevel trees and

     *  place the rest on uncompleted for later processing.

     *  @param trees      The list of trees to be processed.

     *  @param c          The class symbol to be processed.

     */

    public void complete(List<JCCompilationUnit> trees, ClassSymbol c) {

        annotate.enterStart();

        ListBuffer<ClassSymbol> prevUncompleted = uncompleted;

        if (memberEnter.completionEnabled) uncompleted = new ListBuffer<>();

        try {

            // enter all classes, and construct uncompleted list

            classEnter(trees, null);

            // complete all uncompleted classes in memberEnter

            if  (memberEnter.completionEnabled) {

                while (uncompleted.nonEmpty()) {

                    ClassSymbol clazz = uncompleted.next();

                    if (c == null || c == clazz || prevUncompleted == null)

                        clazz.complete();

                    else

                        // defer

                        prevUncompleted.append(clazz);

                }

                // if there remain any unimported toplevels (these must have

                // no classes at all), process their import statements as well.

                for (JCCompilationUnit tree : trees) {

                    if (tree.starImportScope.isEmpty()) {

                        JavaFileObject prev = log.useSource(tree.sourcefile);

                        Env<AttrContext> topEnv = topLevelEnv(tree);

                        memberEnter.memberEnter(tree, topEnv);

                        log.useSource(prev);

                    }

                }

            }

        } finally {

            uncompleted = prevUncompleted;

            annotate.enterDone();

        }

    }

    public void newRound() {