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Truffle is a multi-language framework for executing dynamic languages that achieves high performance when combined with Graal.
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/*
 * Copyright (c) 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 com.oracle.truffle.api.instrumentation;

import java.io.IOException;

import com.oracle.truffle.api.CallTarget;
import com.oracle.truffle.api.CompilerAsserts;
import com.oracle.truffle.api.TruffleLanguage.Env;
import com.oracle.truffle.api.instrumentation.InstrumentableFactory.WrapperNode;
import com.oracle.truffle.api.instrumentation.InstrumentationHandler.AccessorInstrumentHandler;
import com.oracle.truffle.api.nodes.LanguageInfo;
import com.oracle.truffle.api.nodes.Node;
import com.oracle.truffle.api.nodes.RootNode;
import com.oracle.truffle.api.source.Source;
import com.oracle.truffle.api.source.SourceSection;

/**
 * Represents the context of an instrumentation event.
 *
 * Instances of {@link EventContext} should be neither stored, cached nor hashed. One exception is
 * when they are stored in {@link ExecutionEventNode} implementations. The equality and hashing
 * behavior is undefined.
 *
 * @see ExecutionEventNodeFactory
 * @see ExecutionEventListener
 * @since 0.12
 */
public final class EventContext {

    private final ProbeNode probeNode;
    private final SourceSection sourceSection;

    EventContext(ProbeNode probeNode, SourceSection sourceSection) {
        this.sourceSection = sourceSection;
        this.probeNode = probeNode;
    }

    /**
     * Returns the {@link SourceSection} that is being instrumented. The returned source section is
     * final for each {@link EventContext} instance.
     *
     * 
     * Performance note: this is method may be invoked in compiled code and is guaranteed to
     * always return a compilation constant .
     * 
     *
     * @since 0.12
     */
    public SourceSection getInstrumentedSourceSection() {
        return sourceSection;
    }

    /**
     * Accessor to the instrumented node at which the event occurred. The returned AST must not be
     * mutated by the user.
     * 
     * Performance note: this is method may be invoked in compiled code and is guaranteed to
     * always return a compilation constant .
     * 
     *
     * @since 0.12
     */
    public Node getInstrumentedNode() {
        WrapperNode wrapper = probeNode.findWrapper();
        return wrapper != null ? wrapper.getDelegateNode() : null;
    }

    /**
     * Test if language context of the source of the event is initialized.
     *
     * @since 0.26
     */
    public boolean isLanguageContextInitialized() {
        CompilerAsserts.neverPartOfCompilation();
        Node node = getInstrumentedNode();
        if (node == null) {
            return true;
        }
        RootNode root = node.getRootNode();
        if (root == null) {
            return true;
        }
        LanguageInfo languageInfo = root.getLanguageInfo();
        Env env = AccessorInstrumentHandler.engineAccess().getEnvForInstrument(languageInfo);
        return AccessorInstrumentHandler.langAccess().isContextInitialized(env);
    }

    /**
     * Evaluates source of (potentially different) language using the current context. The names of
     * arguments are parameters for the resulting {#link CallTarget} that allow the
     * source to reference the actual parameters passed to
     * {@link CallTarget#call(java.lang.Object...)}.
     *
     * @param source the source to evaluate
     * @param argumentNames the names of {@link CallTarget#call(java.lang.Object...)} arguments that
     *            can be referenced from the source
     * @return the call target representing the parsed result
     * @throws IOException if the parsing or evaluation fails for some reason
     * @since 0.12
     */
    public CallTarget parseInContext(Source source, String... argumentNames) throws IOException {
        Node instrumentedNode = getInstrumentedNode();
        LanguageInfo languageInfo = instrumentedNode.getRootNode().getLanguageInfo();
        if (languageInfo == null) {
            throw new IllegalArgumentException("No language available for given node.");
        }
        Env env = AccessorInstrumentHandler.engineAccess().getEnvForInstrument(languageInfo);
        return AccessorInstrumentHandler.langAccess().parse(env, source, instrumentedNode, argumentNames);
    }

    /**
     * Returns the execution event node that was inserted at this location given an event binding.
     * This is useful to disambiguate multiple bindings from each other when installed at the same
     * source location.
     *
     * @param binding the binding to lookup
     * @since 0.17
     */
    @SuppressWarnings("cast")
    public ExecutionEventNode lookupExecutionEventNode(EventBinding binding) {
        if (!(binding.getElement() instanceof ExecutionEventNodeFactory)) {
            // security check for unsafe generics casts
            throw new IllegalArgumentException(String.format("Binding is not a subtype of %s.", ExecutionEventNodeFactory.class.getSimpleName()));
        }
        return probeNode.lookupExecutionEventNode(binding);
    }

    /*
     * TODO (chumer) a way to parse code in the current language and return something like a node
     * that is directly embeddable into the AST as a @Child.
     */
    /** @since 0.12 */
    @Override
    public String toString() {
        return "EventContext[source=" + getInstrumentedSourceSection() + "]";
    }

}