/*

 * Copyright (c) 2014, 2015, 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.

 *

 * 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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 * questions.

 */

package org.graalvm.compiler.core.match;

import static org.graalvm.compiler.debug.GraalDebugConfig.Options.LogVerbose;

import java.util.List;

import jdk.vm.ci.meta.Value;

import org.graalvm.compiler.core.gen.NodeLIRBuilder;

import org.graalvm.compiler.core.match.MatchPattern.MatchResultCode;

import org.graalvm.compiler.core.match.MatchPattern.Result;

import org.graalvm.compiler.debug.Debug;

import org.graalvm.compiler.debug.DebugCounter;

import org.graalvm.compiler.graph.GraalGraphError;

import org.graalvm.compiler.graph.Node;

import org.graalvm.compiler.nodeinfo.Verbosity;

/**

 * A named {@link MatchPattern} along with a {@link MatchGenerator} that can be evaluated to replace

 * one or more {@link Node}s with a single {@link Value}.

 */

public class MatchStatement {

    private static final DebugCounter MatchStatementSuccess = Debug.counter("MatchStatementSuccess");

    /**

     * A printable name for this statement. Usually it's just the name of the method doing the

     * emission.

     */

    private final String name;

    /**

     * The actual match pattern.

     */

    private final MatchPattern pattern;

    /**

     * The method in the {@link NodeLIRBuilder} subclass that will actually do the code emission.

     */

    private MatchGenerator generatorMethod;

    /**

     * The name of arguments in the order they are expected to be passed to the generator method.

     */

    private String[] arguments;

    public MatchStatement(String name, MatchPattern pattern, MatchGenerator generator, String[] arguments) {

        this.name = name;

        this.pattern = pattern;

        this.generatorMethod = generator;

        this.arguments = arguments;

    }

    /**

     * Attempt to match the current statement against a Node.

     *

     * @param builder the current builder instance.

     * @param node the node to be matched

     * @param nodes the nodes in the current block

     * @return true if the statement matched something and set a {@link ComplexMatchResult} to be

     *         evaluated by the NodeLIRBuilder.

     */

    public boolean generate(NodeLIRBuilder builder, int index, Node node, List<Node> nodes) {

        assert index == nodes.indexOf(node);

        // Check that the basic shape matches

        Result result = pattern.matchShape(node, this);

        if (result != Result.OK) {

            return false;

        }

        // Now ensure that the other safety constraints are matched.

        MatchContext context = new MatchContext(builder, this, index, node, nodes);

        result = pattern.matchUsage(node, context);

        if (result == Result.OK) {

            // Invoke the generator method and set the result if it's non null.

            ComplexMatchResult value = generatorMethod.match(builder.getNodeMatchRules(), buildArgList(context));

            if (value != null) {

                context.setResult(value);

                MatchStatementSuccess.increment();

                Debug.counter("MatchStatement[%s]", getName()).increment();

                return true;

            }

            // The pattern matched but some other code generation constraint disallowed code

            // generation for the pattern.

            if (LogVerbose.getValue()) {

                Debug.log("while matching %s|%s %s %s returned null", context.getRoot().toString(Verbosity.Id), context.getRoot().getClass().getSimpleName(), getName(), generatorMethod.getName());

                Debug.log("with nodes %s", formatMatch(node));

            }

        } else {

            if (LogVerbose.getValue() && result.code != MatchResultCode.WRONG_CLASS) {

                Debug.log("while matching %s|%s %s %s", context.getRoot().toString(Verbosity.Id), context.getRoot().getClass().getSimpleName(), getName(), result);

            }

        }

        return false;

    }

    /**

     * @param context

     * @return the Nodes captured by the match rule in the order expected by the generatorMethod

     */

    private Object[] buildArgList(MatchContext context) {

        Object[] result = new Object[arguments.length];

        for (int i = 0; i < arguments.length; i++) {

            if ("root".equals(arguments[i])) {

                result[i] = context.getRoot();

            } else {

                result[i] = context.namedNode(arguments[i]);

                if (result[i] == null) {

                    throw new GraalGraphError("Can't find named node %s", arguments[i]);

                }

            }

        }

        return result;

    }

    public String formatMatch(Node root) {

        return pattern.formatMatch(root);

    }

    public MatchPattern getPattern() {

        return pattern;

    }

    public String getName() {

        return name;

    }

    @Override

    public String toString() {

        return pattern.toString();

    }

}