/*

 * Copyright (c) 2013, 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.jvm;

import java.util.Map;

import java.util.Map.Entry;

import java.util.WeakHashMap;

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

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

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

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

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

/** This class contains a one to many relation between a tree and a set of variables.

 *  The relation implies that the given tree closes the DA (definite assignment)

 *  range for the set of variables.

 *

 *  <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 LVTRanges {

    /** The context key for the LVT ranges. */

    protected static final Context.Key<LVTRanges> lvtRangesKey = new Context.Key<>();

    /** Get the LVTRanges instance for this context. */

    public static LVTRanges instance(Context context) {

        LVTRanges instance = context.get(lvtRangesKey);

        if (instance == null) {

            instance = new LVTRanges(context);

        }

        return instance;

    }

    private static final long serialVersionUID = 1812267524140424433L;

    protected Context context;

    protected Map<MethodSymbol, Map<JCTree, List<VarSymbol>>>

            aliveRangeClosingTrees = new WeakHashMap<>();

    public LVTRanges(Context context) {

        this.context = context;

        context.put(lvtRangesKey, this);

    }

    public List<VarSymbol> getVars(MethodSymbol method, JCTree tree) {

        Map<JCTree, List<VarSymbol>> varMap = aliveRangeClosingTrees.get(method);

        return (varMap != null) ? varMap.get(tree) : null;

    }

    public boolean containsKey(MethodSymbol method, JCTree tree) {

        Map<JCTree, List<VarSymbol>> varMap = aliveRangeClosingTrees.get(method);

        if (varMap == null) {

            return false;

        }

        return varMap.containsKey(tree);

    }

    public void setEntry(MethodSymbol method, JCTree tree, List<VarSymbol> vars) {

        Map<JCTree, List<VarSymbol>> varMap = aliveRangeClosingTrees.get(method);

        if (varMap != null) {

            varMap.put(tree, vars);

        } else {

            varMap = new WeakHashMap<>();

            varMap.put(tree, vars);

            aliveRangeClosingTrees.put(method, varMap);

        }

    }

    public List<VarSymbol> removeEntry(MethodSymbol method, JCTree tree) {

        Map<JCTree, List<VarSymbol>> varMap = aliveRangeClosingTrees.get(method);

        if (varMap != null) {

            List<VarSymbol> result = varMap.remove(tree);

            if (varMap.isEmpty()) {

                aliveRangeClosingTrees.remove(method);

            }

            return result;

        }

        return null;

    }

    /* This method should be used for debugging LVT related issues.

     */

    @Override

    public String toString() {

        String result = "";

        for (Entry<MethodSymbol, Map<JCTree, List<VarSymbol>>> mainEntry: aliveRangeClosingTrees.entrySet()) {

            result += "Method: \n" + mainEntry.getKey().flatName() + "\n";

            int i = 1;

            for (Entry<JCTree, List<VarSymbol>> treeEntry: mainEntry.getValue().entrySet()) {

                result += "    Tree " + i + ": \n" + treeEntry.getKey().toString() + "\n";

                result += "        Variables closed:\n";

                for (VarSymbol var: treeEntry.getValue()) {

                    result += "            " + var.toString();

                }

                result += "\n";

                i++;

            }

        }

        return result;

    }

}