/*
 * Copyright (c) 2003, 2018, 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
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 */

package com.sun.tools.javac.comp;

import java.util.EnumSet;
import java.util.Set;

import com.sun.tools.javac.code.*;
import com.sun.tools.javac.code.Scope.WriteableScope;
import com.sun.tools.javac.tree.*;
import com.sun.tools.javac.util.*;
import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
import com.sun.tools.javac.util.JCDiagnostic.Error;

import com.sun.tools.javac.code.Symbol.*;
import com.sun.tools.javac.code.Type.*;
import com.sun.tools.javac.resources.CompilerProperties.Errors;
import com.sun.tools.javac.tree.JCTree.*;

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

Resolves field, method and constructor header, and constructs corresponding Symbols.
 
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.
/** Resolves field, method and constructor header, and constructs corresponding Symbols.
 *
 *  <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 MemberEnter extends JCTree.Visitor {
    protected static final Context.Key<MemberEnter> memberEnterKey = new Context.Key<>();

    private final Enter enter;
    private final Log log;
    private final Check chk;
    private final Attr attr;
    private final Symtab syms;
    private final Annotate annotate;
    private final Types types;
    private final DeferredLintHandler deferredLintHandler;

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

    protected MemberEnter(Context context) {
        context.put(memberEnterKey, this);
        enter = Enter.instance(context);
        log = Log.instance(context);
        chk = Check.instance(context);
        attr = Attr.instance(context);
        syms = Symtab.instance(context);
        annotate = Annotate.instance(context);
        types = Types.instance(context);
        deferredLintHandler = DeferredLintHandler.instance(context);
    }

    
Construct method type from method signature.
 @param typarams    The method's type parameters.
 @param params      The method's value parameters.
 @param res             The method's result type,
                null if it is a constructor.
 @param recvparam       The method's receiver parameter,
                null if none given; TODO: or already set here?
 @param thrown      The method's thrown exceptions.
 @param env             The method's (local) environment.
/** Construct method type from method signature.
     *  @param typarams    The method's type parameters.
     *  @param params      The method's value parameters.
     *  @param res             The method's result type,
     *                 null if it is a constructor.
     *  @param recvparam       The method's receiver parameter,
     *                 null if none given; TODO: or already set here?
     *  @param thrown      The method's thrown exceptions.
     *  @param env             The method's (local) environment.
     */
    Type signature(MethodSymbol msym,
                   List<JCTypeParameter> typarams,
                   List<JCVariableDecl> params,
                   JCTree res,
                   JCVariableDecl recvparam,
                   List<JCExpression> thrown,
                   Env<AttrContext> env) {

        // Enter and attribute type parameters.
        List<Type> tvars = enter.classEnter(typarams, env);
        attr.attribTypeVariables(typarams, env);

        // Enter and attribute value parameters.
        ListBuffer<Type> argbuf = new ListBuffer<>();
        for (List<JCVariableDecl> l = params; l.nonEmpty(); l = l.tail) {
            memberEnter(l.head, env);
            argbuf.append(l.head.vartype.type);
        }

        // Attribute result type, if one is given.
        Type restype = res == null ? syms.voidType : attr.attribType(res, env);

        // Attribute receiver type, if one is given.
        Type recvtype;
        if (recvparam!=null) {
            memberEnter(recvparam, env);
            recvtype = recvparam.vartype.type;
        } else {
            recvtype = null;
        }

        // Attribute thrown exceptions.
        ListBuffer<Type> thrownbuf = new ListBuffer<>();
        for (List<JCExpression> l = thrown; l.nonEmpty(); l = l.tail) {
            Type exc = attr.attribType(l.head, env);
            if (!exc.hasTag(TYPEVAR)) {
                exc = chk.checkClassType(l.head.pos(), exc);
            } else if (exc.tsym.owner == msym) {
                //mark inference variables in 'throws' clause
                exc.tsym.flags_field |= THROWS;
            }
            thrownbuf.append(exc);
        }
        MethodType mtype = new MethodType(argbuf.toList(),
                                    restype,
                                    thrownbuf.toList(),
                                    syms.methodClass);
        mtype.recvtype = recvtype;

        return tvars.isEmpty() ? mtype : new ForAll(tvars, mtype);
    }

/* ********************************************************************
 * Visitor methods for member enter
 *********************************************************************/

    
Visitor argument: the current environment
/** Visitor argument: the current environment
     */
    protected Env<AttrContext> env;

    
Enter field and method definitions and process import
 clauses, catching any completion failure exceptions.
/** Enter field and method definitions and process import
     *  clauses, catching any completion failure exceptions.
     */
    protected void memberEnter(JCTree tree, Env<AttrContext> env) {
        Env<AttrContext> prevEnv = this.env;
        try {
            this.env = env;
            tree.accept(this);
        }  catch (CompletionFailure ex) {
            chk.completionError(tree.pos(), ex);
        } finally {
            this.env = prevEnv;
        }
    }

    
Enter members from a list of trees.
/** Enter members from a list of trees.
     */
    void memberEnter(List<? extends JCTree> trees, Env<AttrContext> env) {
        for (List<? extends JCTree> l = trees; l.nonEmpty(); l = l.tail)
            memberEnter(l.head, env);
    }

    public void visitMethodDef(JCMethodDecl tree) {
        WriteableScope enclScope = enter.enterScope(env);
        MethodSymbol m = new MethodSymbol(0, tree.name, null, enclScope.owner);
        m.flags_field = chk.checkFlags(tree.pos(), tree.mods.flags, m, tree);
        tree.sym = m;

        //if this is a default method, add the DEFAULT flag to the enclosing interface
        if ((tree.mods.flags & DEFAULT) != 0) {
            m.enclClass().flags_field |= DEFAULT;
        }

        Env<AttrContext> localEnv = methodEnv(tree, env);
        DiagnosticPosition prevLintPos = deferredLintHandler.setPos(tree.pos());
        try {
            // Compute the method type
            m.type = signature(m, tree.typarams, tree.params,
                               tree.restype, tree.recvparam,
                               tree.thrown,
                               localEnv);
        } finally {
            deferredLintHandler.setPos(prevLintPos);
        }

        if (types.isSignaturePolymorphic(m)) {
            m.flags_field |= SIGNATURE_POLYMORPHIC;
        }

        // Set m.params
        ListBuffer<VarSymbol> params = new ListBuffer<>();
        JCVariableDecl lastParam = null;
        for (List<JCVariableDecl> l = tree.params; l.nonEmpty(); l = l.tail) {
            JCVariableDecl param = lastParam = l.head;
            params.append(Assert.checkNonNull(param.sym));
        }
        m.params = params.toList();

        // mark the method varargs, if necessary
        if (lastParam != null && (lastParam.mods.flags & Flags.VARARGS) != 0)
            m.flags_field |= Flags.VARARGS;

        localEnv.info.scope.leave();
        if (chk.checkUnique(tree.pos(), m, enclScope)) {
        enclScope.enter(m);
        }

        annotate.annotateLater(tree.mods.annotations, localEnv, m, tree.pos());
        // Visit the signature of the method. Note that
        // TypeAnnotate doesn't descend into the body.
        annotate.queueScanTreeAndTypeAnnotate(tree, localEnv, m, tree.pos());

        if (tree.defaultValue != null) {
            m.defaultValue = annotate.unfinishedDefaultValue(); // set it to temporary sentinel for now
            annotate.annotateDefaultValueLater(tree.defaultValue, localEnv, m, tree.pos());
        }
    }

    
Create a fresh environment for method bodies.
 @param tree     The method definition.
 @param env      The environment current outside of the method definition.
/** Create a fresh environment for method bodies.
     *  @param tree     The method definition.
     *  @param env      The environment current outside of the method definition.
     */
    Env<AttrContext> methodEnv(JCMethodDecl tree, Env<AttrContext> env) {
        Env<AttrContext> localEnv =
            env.dup(tree, env.info.dup(env.info.scope.dupUnshared(tree.sym)));
        localEnv.enclMethod = tree;
        if (tree.sym.type != null) {
            //when this is called in the enter stage, there's no type to be set
            localEnv.info.returnResult = attr.new ResultInfo(KindSelector.VAL,
                                                             tree.sym.type.getReturnType());
        }
        if ((tree.mods.flags & STATIC) != 0) localEnv.info.staticLevel++;
        return localEnv;
    }

    public void visitVarDef(JCVariableDecl tree) {
        Env<AttrContext> localEnv = env;
        if ((tree.mods.flags & STATIC) != 0 ||
            (env.info.scope.owner.flags() & INTERFACE) != 0) {
            localEnv = env.dup(tree, env.info.dup());
            localEnv.info.staticLevel++;
        }
        DiagnosticPosition prevLintPos = deferredLintHandler.setPos(tree.pos());

        try {
            if (TreeInfo.isEnumInit(tree)) {
                attr.attribIdentAsEnumType(localEnv, (JCIdent)tree.vartype);
            } else if (!tree.isImplicitlyTyped()) {
                attr.attribType(tree.vartype, localEnv);
                if (TreeInfo.isReceiverParam(tree))
                    checkReceiver(tree, localEnv);
            }
        } finally {
            deferredLintHandler.setPos(prevLintPos);
        }

        if ((tree.mods.flags & VARARGS) != 0) {
            //if we are entering a varargs parameter, we need to
            //replace its type (a plain array type) with the more
            //precise VarargsType --- we need to do it this way
            //because varargs is represented in the tree as a
            //modifier on the parameter declaration, and not as a
            //distinct type of array node.
            ArrayType atype = (ArrayType)tree.vartype.type;
            tree.vartype.type = atype.makeVarargs();
        }
        WriteableScope enclScope = enter.enterScope(env);
        Type vartype = tree.isImplicitlyTyped()
                ? env.info.scope.owner.kind == MTH ? Type.noType : syms.errType
                : tree.vartype.type;
        VarSymbol v = new VarSymbol(0, tree.name, vartype, enclScope.owner);
        v.flags_field = chk.checkFlags(tree.pos(), tree.mods.flags, v, tree);
        tree.sym = v;
        if (tree.init != null) {
            v.flags_field |= HASINIT;
            if ((v.flags_field & FINAL) != 0 &&
                needsLazyConstValue(tree.init)) {
                Env<AttrContext> initEnv = getInitEnv(tree, env);
                initEnv.info.enclVar = v;
                v.setLazyConstValue(initEnv(tree, initEnv), attr, tree);
            }
        }
        if (chk.checkUnique(tree.pos(), v, enclScope)) {
            chk.checkTransparentVar(tree.pos(), v, enclScope);
            enclScope.enter(v);
        }

        annotate.annotateLater(tree.mods.annotations, localEnv, v, tree.pos());
        if (!tree.isImplicitlyTyped()) {
            annotate.queueScanTreeAndTypeAnnotate(tree.vartype, localEnv, v, tree.pos());
        }

        v.pos = tree.pos;
    }
    // where
    void checkType(JCTree tree, Type type, Error errorKey) {
        if (!tree.type.isErroneous() && !types.isSameType(tree.type, type)) {
            log.error(tree, errorKey);
        }
    }
    void checkReceiver(JCVariableDecl tree, Env<AttrContext> localEnv) {
        attr.attribExpr(tree.nameexpr, localEnv);
        MethodSymbol m = localEnv.enclMethod.sym;
        if (m.isConstructor()) {
            Type outertype = m.owner.owner.type;
            if (outertype.hasTag(TypeTag.METHOD)) {
                // we have a local inner class
                outertype = m.owner.owner.owner.type;
            }
            if (outertype.hasTag(TypeTag.CLASS)) {
                checkType(tree.vartype, outertype, Errors.IncorrectConstructorReceiverType(outertype, tree.vartype.type));
                checkType(tree.nameexpr, outertype, Errors.IncorrectConstructorReceiverName(outertype, tree.nameexpr.type));
            } else {
                log.error(tree, Errors.ReceiverParameterNotApplicableConstructorToplevelClass);
            }
        } else {
            checkType(tree.vartype, m.owner.type, Errors.IncorrectReceiverType(m.owner.type, tree.vartype.type));
            checkType(tree.nameexpr, m.owner.type, Errors.IncorrectReceiverName(m.owner.type, tree.nameexpr.type));
        }
    }

    public boolean needsLazyConstValue(JCTree tree) {
        InitTreeVisitor initTreeVisitor = new InitTreeVisitor();
        tree.accept(initTreeVisitor);
        return initTreeVisitor.result;
    }

    
Visitor class for expressions which might be constant expressions,
 as per JLS 15.28 (Constant Expressions).
/** Visitor class for expressions which might be constant expressions,
     *  as per JLS 15.28 (Constant Expressions).
     */
    static class InitTreeVisitor extends JCTree.Visitor {

        private static final Set<Tag> ALLOWED_OPERATORS =
                EnumSet.of(Tag.POS, Tag.NEG, Tag.NOT, Tag.COMPL, Tag.PLUS, Tag.MINUS,
                           Tag.MUL, Tag.DIV, Tag.MOD, Tag.SL, Tag.SR, Tag.USR,
                           Tag.LT, Tag.LE, Tag.GT, Tag.GE, Tag.EQ, Tag.NE,
                           Tag.BITAND, Tag.BITXOR, Tag.BITOR, Tag.AND, Tag.OR);

        boolean result = true;

        @Override
        public void visitTree(JCTree tree) {
            result = false;
        }

        @Override
        public void visitLiteral(JCLiteral that) {}

        @Override
        public void visitTypeCast(JCTypeCast tree) {
            tree.expr.accept(this);
        }

        @Override
        public void visitUnary(JCUnary that) {
            if (!ALLOWED_OPERATORS.contains(that.getTag())) {
                result = false;
                return ;
            }
            that.arg.accept(this);
        }

        @Override
        public void visitBinary(JCBinary that) {
            if (!ALLOWED_OPERATORS.contains(that.getTag())) {
                result = false;
                return ;
            }
            that.lhs.accept(this);
            that.rhs.accept(this);
        }

        @Override
        public void visitConditional(JCConditional tree) {
            tree.cond.accept(this);
            tree.truepart.accept(this);
            tree.falsepart.accept(this);
        }

        @Override
        public void visitParens(JCParens tree) {
            tree.expr.accept(this);
        }

        @Override
        public void visitIdent(JCIdent that) {}

        @Override
        public void visitSelect(JCFieldAccess tree) {
            tree.selected.accept(this);
        }
    }

    
Create a fresh environment for a variable's initializer.
 If the variable is a field, the owner of the environment's scope
 is be the variable itself, otherwise the owner is the method
 enclosing the variable definition.
 @param tree     The variable definition.
 @param env      The environment current outside of the variable definition.
/** Create a fresh environment for a variable's initializer.
     *  If the variable is a field, the owner of the environment's scope
     *  is be the variable itself, otherwise the owner is the method
     *  enclosing the variable definition.
     *
     *  @param tree     The variable definition.
     *  @param env      The environment current outside of the variable definition.
     */
    Env<AttrContext> initEnv(JCVariableDecl tree, Env<AttrContext> env) {
        Env<AttrContext> localEnv = env.dupto(new AttrContextEnv(tree, env.info.dup()));
        if (tree.sym.owner.kind == TYP) {
            localEnv.info.scope = env.info.scope.dupUnshared(tree.sym);
        }
        if ((tree.mods.flags & STATIC) != 0 ||
                ((env.enclClass.sym.flags() & INTERFACE) != 0 && env.enclMethod == null))
            localEnv.info.staticLevel++;
        return localEnv;
    }

    
Default member enter visitor method: do nothing
/** Default member enter visitor method: do nothing
     */
    public void visitTree(JCTree tree) {
    }

    public void visitErroneous(JCErroneous tree) {
        if (tree.errs != null)
            memberEnter(tree.errs, env);
    }

    public Env<AttrContext> getMethodEnv(JCMethodDecl tree, Env<AttrContext> env) {
        Env<AttrContext> mEnv = methodEnv(tree, env);
        mEnv.info.lint = mEnv.info.lint.augment(tree.sym);
        for (List<JCTypeParameter> l = tree.typarams; l.nonEmpty(); l = l.tail)
            mEnv.info.scope.enterIfAbsent(l.head.type.tsym);
        for (List<JCVariableDecl> l = tree.params; l.nonEmpty(); l = l.tail)
            mEnv.info.scope.enterIfAbsent(l.head.sym);
        return mEnv;
    }

    public Env<AttrContext> getInitEnv(JCVariableDecl tree, Env<AttrContext> env) {
        Env<AttrContext> iEnv = initEnv(tree, env);
        return iEnv;
    }
}