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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) 2015, 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.
 */

/*
 @ApiInfo(
 group="Stable"
 )
 */

/**
 * Control over {@link com.oracle.truffle.api.debug.Debugger debugging} of your
 * {@link com.oracle.truffle.api.vm.PolyglotEngine}. Each
 * {@link com.oracle.truffle.api.vm.PolyglotEngine} is inherently capable to run in debugging mode -
 * there is just one thing to do - the {@link com.oracle.truffle.api.vm.PolyglotEngine.Builder
 * creator of the virtual machine} needs to turn debugging on when constructing its polyglot
 * execution engine:
 * 
 *  * vm = {@link com.oracle.truffle.api.vm.PolyglotEngine#buildNew()}.
 *     {@link com.oracle.truffle.api.vm.PolyglotEngine.Builder#onEvent(com.oracle.truffle.api.vm.EventConsumer) onEvent}(new {@link com.oracle.truffle.api.vm.EventConsumer EventConsumer}
 *     {@code <}{@link com.oracle.truffle.api.debug.ExecutionEvent}{@code >}() {
 *         public void handle({@link com.oracle.truffle.api.debug.ExecutionEvent} ev) {
 *             // configure the virtual machine as {@link com.oracle.truffle.api.vm.PolyglotEngine#eval(com.oracle.truffle.api.source.Source) new execution} is starting
 *         }
 *     }).
 *     {@link com.oracle.truffle.api.vm.PolyglotEngine.Builder#onEvent(com.oracle.truffle.api.vm.EventConsumer) onEvent}(new {@link com.oracle.truffle.api.vm.EventConsumer EventConsumer}{@code <}
 *     {@link com.oracle.truffle.api.debug.SuspendedEvent}{@code >}() {
 *         public void handle({@link com.oracle.truffle.api.debug.SuspendedEvent} ev) {
 *             // execution is suspended on a breakpoint or on a step - decide what next
 *         }
 *     }).{@link com.oracle.truffle.api.vm.PolyglotEngine.Builder#build() build()};
 * 
 * 
 * The debugging is controlled by events emitted by the Truffle virtual machine at important
 * moments. The {@link com.oracle.truffle.api.debug.ExecutionEvent} is sent when a call to
 * {@link com.oracle.truffle.api.vm.PolyglotEngine#eval(com.oracle.truffle.api.source.Source)} is
 * made and allows one to configure {@link com.oracle.truffle.api.debug.Breakpoint breakpoints}
 * and/or decide whether the program should
 * {@link com.oracle.truffle.api.debug.ExecutionEvent#prepareStepInto() step-into} or
 * {@link com.oracle.truffle.api.debug.ExecutionEvent#prepareContinue() just run}. Once the
 * execution is suspended a {@link com.oracle.truffle.api.debug.SuspendedEvent} is generated which
 * allows one to inspect the stack and choose the further execution mode (
 * {@link com.oracle.truffle.api.debug.SuspendedEvent#prepareStepInto(int) step-into},
 * {@link com.oracle.truffle.api.debug.SuspendedEvent#prepareStepOver(int) step-over},
 * {@link com.oracle.truffle.api.debug.SuspendedEvent#prepareStepOut() step-out},
 * {@link com.oracle.truffle.api.debug.SuspendedEvent#prepareContinue() continue}).
 * 
 * The events methods are only available when the event is being delivered and shouldn't be used
 * anytime later. Both events however provide access to
 * {@link com.oracle.truffle.api.debug.Debugger} which can be kept and used during whole existence
 * of the {@link com.oracle.truffle.api.vm.PolyglotEngine}.
 * {@link com.oracle.truffle.api.debug.Debugger} is the central class that keeps information about
 * {@link com.oracle.truffle.api.debug.Debugger#getBreakpoints() registered breakpoints} and allows
 * one create new {@link com.oracle.truffle.api.debug.Breakpoint ones}.
 *
 * 
Turning on Stepping Mode
 *
 * In case you want your execution to pause on first statement, register for
 * {@link com.oracle.truffle.api.debug.ExecutionEvent} and once delivered call
 * {@link com.oracle.truffle.api.debug.ExecutionEvent#prepareStepInto()}.
 *
 * Register a {@link com.oracle.truffle.api.debug.Breakpoint}
 *
 * Wait for execution to be started - which generates an
 * {@link com.oracle.truffle.api.debug.ExecutionEvent}. Use its
 * {@link com.oracle.truffle.api.debug.Debugger ev.getDebugger}() methods to submit breakpoints.
 *
 * Enable Debugging for your Language
 *
 * The platform's core support for {@link com.oracle.truffle.api.debug.Debugger debugging} is
 * language-agnostic. A {@link com.oracle.truffle.api.TruffleLanguage language implementation}
 * enables debugging by supplying extra information in every AST that configures debugger behavior
 * for code written in that particular language.
 * 
 * This extra information is expressed as
 * {@linkplain com.oracle.truffle.api.source.SourceSection#withTags(java.lang.String...) tags}. The
 * language implementation applies tags to the {@link com.oracle.truffle.api.source.SourceSection
 * source information} associated with {@link com.oracle.truffle.api.nodes.Node nodes} relevant to
 * debugging. At this time the debugger requries two tags for basic behavior; more tags may be
 * required in the future as the debugger acquires more functionality.
 * 

 * {@link com.oracle.truffle.api.debug.Debugger#HALT_TAG}: must be applied to every Node where
 * the debugger should halt during ordinary stepping. This typically corresponds to
 * "statements" in each language.
 * {@link com.oracle.truffle.api.debug.Debugger#CALL_TAG}: must be applied to every Node where
 * the debugger should halt when either returning or stepping out from a call.
 * This typically corresponds to function/method calls in each language.
 * 
 */
package com.oracle.truffle.api.debug;