/*

 * Copyright (c) 2003, 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 jdk.javadoc.internal.tool;

import com.sun.source.util.TreePath;

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

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

import com.sun.tools.javac.comp.MemberEnter;

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

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

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

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

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

/**

 *  Javadoc's own memberEnter phase does a few things above and beyond that

 *  done by javac.

 *

 *  <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>

 *

 *  @author Neal Gafter

 */

public class JavadocMemberEnter extends MemberEnter {

    public static JavadocMemberEnter instance0(Context context) {

        MemberEnter instance = context.get(memberEnterKey);

        if (instance == null)

            instance = new JavadocMemberEnter(context);

        return (JavadocMemberEnter)instance;

    }

    public static void preRegister(Context context) {

    }

    final ToolEnvironment toolEnv;

    protected JavadocMemberEnter(Context context) {

        super(context);

        toolEnv = ToolEnvironment.instance(context);

    }

    @Override

    public void visitMethodDef(JCMethodDecl tree) {

        super.visitMethodDef(tree);

        MethodSymbol meth = tree.sym;

        if (meth == null || meth.kind != MTH) return;

        TreePath treePath = toolEnv.getTreePath(env.toplevel, env.enclClass, tree);

        // do not add those methods that may be mandated by the spec,

        // or those that are synthesized, thus if it does not exist in

        // tree best to let other logic determine the TreePath.

        if (env.enclClass.defs.contains(tree)) {

            toolEnv.setElementToTreePath(meth, treePath);

        }

        // release resources

        tree.body = null;

    }

    @Override

    public void visitVarDef(JCVariableDecl tree) {

        if (tree.init != null) {

            boolean isFinal = (tree.mods.flags & FINAL) != 0

                    || (env.enclClass.mods.flags & INTERFACE) != 0;

            if (!isFinal || containsNonConstantExpression(tree.init)) {

                // Avoid unnecessary analysis and release resources.

                // In particular, remove non-constant expressions

                // which may trigger Attr.attribClass, since

                // method bodies are also removed, in visitMethodDef.

                tree.init = null;

            }

        }

        super.visitVarDef(tree);

        if (tree.sym != null && tree.sym.kind == VAR && !isParameter(tree.sym)) {

            toolEnv.setElementToTreePath(tree.sym, toolEnv.getTreePath(env.toplevel, env.enclClass, tree));

        }

    }

    private static boolean isParameter(VarSymbol var) {

        return (var.flags() & Flags.PARAMETER) != 0;

    }

    /**

     * Simple analysis of an expression tree to see if it contains tree nodes

     * for any non-constant expression. This does not include checking references

     * to other fields which may or may not be constant.

     */

    private static boolean containsNonConstantExpression(JCExpression tree) {

        return new MaybeConstantExpressionScanner().containsNonConstantExpression(tree);

    }

    /**

     * See JLS 15.18, Constant Expression

     */

    private static class MaybeConstantExpressionScanner extends JCTree.Visitor {

        boolean maybeConstantExpr = true;

        public boolean containsNonConstantExpression(JCExpression tree) {

            scan(tree);

            return !maybeConstantExpr;

        }

        public void scan(JCTree tree) {

            // short circuit scan when end result is definitely false

            if (maybeConstantExpr && tree != null)

                tree.accept(this);

        }

        @Override

        /** default for any non-overridden visit method. */

        public void visitTree(JCTree tree) {

            maybeConstantExpr = false;

        }

        @Override

        public void visitBinary(JCBinary tree) {

            switch (tree.getTag()) {

                case MUL: case DIV: case MOD:

                case PLUS: case MINUS:

                case SL: case SR: case USR:

                case LT: case LE: case GT: case GE:

                case EQ: case NE:

                case BITAND: case BITXOR: case BITOR:

                case AND: case OR:

                    break;

                default:

                    maybeConstantExpr = false;

            }

        }

        @Override

        public void visitConditional(JCConditional tree) {

            scan(tree.cond);

            scan(tree.truepart);

            scan(tree.falsepart);

        }

        @Override

        public void visitIdent(JCIdent tree) { }

        @Override

        public void visitLiteral(JCLiteral tree) { }

        @Override

        public void visitParens(JCParens tree) {

            scan(tree.expr);

        }

        @Override

        public void visitSelect(JCTree.JCFieldAccess tree) {

            scan(tree.selected);

        }

        @Override

        public void visitTypeCast(JCTypeCast tree) {

            scan(tree.clazz);

            scan(tree.expr);

        }

        @Override

        public void visitTypeIdent(JCPrimitiveTypeTree tree) { }

        @Override

        public void visitUnary(JCUnary tree) {

            switch (tree.getTag()) {

                case POS: case NEG: case COMPL: case NOT:

                    break;

                default:

                    maybeConstantExpr = false;

            }

        }

    }

}