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package com.oracle.truffle.api.debug;

import com.oracle.truffle.api.CompilerDirectives;
import com.oracle.truffle.api.RootCallTarget;
import com.oracle.truffle.api.TruffleStackTraceElement;
import com.oracle.truffle.api.frame.Frame;
import com.oracle.truffle.api.frame.MaterializedFrame;
import com.oracle.truffle.api.interop.NodeLibrary;
import com.oracle.truffle.api.interop.UnsupportedMessageException;
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.SourceSection;

Represents a trace element in the guest language stack trace. A guest language trace element consists of a name, the current source location and scopes containing local variables and arguments. 
 The difference between this class and DebugStackFrame is the limited life-time of DebugStackFrame, that is associated with a SuspendedEvent. 
See Also:
DebugException.getDebugStackTrace()
Since:
19.0/**
 * Represents a trace element in the guest language stack trace. A guest language trace element
 * consists of a {@link #getName() name}, the current {@link #getSourceSection() source location}
 * and {@link #getScope() scopes} containing local variables and arguments.
 * <p>
 * The difference between this class and {@link DebugStackFrame} is the limited life-time of
 * {@link DebugStackFrame}, that is associated with a {@link SuspendedEvent}.
 *
 * @see DebugException#getDebugStackTrace()
 * @since 19.0
 */
public final class DebugStackTraceElement {

    private final DebuggerSession session;
    final TruffleStackTraceElement traceElement;
    private final StackTraceElement hostTraceElement;
    private StackTraceElement stackTraceElement;

    DebugStackTraceElement(DebuggerSession session, TruffleStackTraceElement traceElement) {
        this.session = session;
        this.traceElement = traceElement;
        this.hostTraceElement = null;
    }

    DebugStackTraceElement(DebuggerSession session, StackTraceElement hostTraceElement) {
        this.session = session;
        this.traceElement = null;
        this.hostTraceElement = hostTraceElement;
    }

    
Returns whether this trace element is a language implementation artifact.

The decision to mark a method as internal is language-specific, reflects judgments
about tool usability, and is subject to change.
Since:
19.0/**
     * Returns whether this trace element is a language implementation artifact.
     * <p>
     * The decision to mark a method as <em>internal</em> is language-specific, reflects judgments
     * about tool usability, and is subject to change.
     *
     * @since 19.0
     */
    public boolean isInternal() {
        if (isHost()) {
            return false;
        }
        RootNode root = findCurrentRoot();
        if (root == null) {
            return true;
        }
        return root.isInternal();
    }

    
Returns true if this element is a host element. Host elements provide stack trace element, have no scope, and no source section. 
 Host elements are provided only when 
host info is set to true.
See Also:
DebuggerSession.setShowHostStackFrames(boolean)
Since:
20.3/**
     * Returns <code>true</code> if this element is a host element. Host elements provide
     * {@link #getHostTraceElement() stack trace element}, have no {@link #getScope() scope}, and no
     * {@link #getSourceSection() source section}.
     * <p>
     * Host elements are provided only when {@link DebuggerSession#setShowHostStackFrames(boolean)
     * host info} is set to <code>true</code>.
     *
     * @since 20.3
     * @see DebuggerSession#setShowHostStackFrames(boolean)
     */
    public boolean isHost() {
        return hostTraceElement != null;
    }

    
Provides a host element. Returns the host stack trace element if and only if this is host element. 
See Also:
isHost()
Returns:
the host stack trace element, or null when not a host element.
Since:
20.3/**
     * Provides a host element. Returns the host stack trace element if and only if this is
     * {@link #isHost() host} element.
     *
     * @return the host stack trace element, or <code>null</code> when not a host element.
     * @since 20.3
     * @see #isHost()
     */
    public StackTraceElement getHostTraceElement() {
        return hostTraceElement;
    }

    
A description of the trace element. If the language does not provide such a description then
null is returned.
Since:
19.0/**
     * A description of the trace element. If the language does not provide such a description then
     * <code>null</code> is returned.
     *
     * @since 19.0
     */
    public String getName() {
        if (hostTraceElement != null) {
            return hostTraceElement.getClassName() + '.' + hostTraceElement.getMethodName();
        }
        RootNode root = findCurrentRoot();
        if (root == null) {
            return null;
        }
        try {
            return root.getName();
        } catch (ThreadDeath td) {
            throw td;
        } catch (Throwable ex) {
            throw new DebugException(session, ex, root.getLanguageInfo(), null, true, null);
        }
    }

    private String getName0() {
        RootNode root = findCurrentRoot();
        if (root == null) {
            return null;
        }
        try {
            return root.getName();
        } catch (ThreadDeath td) {
            throw td;
        } catch (Throwable ex) {
            return null;
        }
    }

    
Returns the source section location of this trace element. The source section is
null if the source location is not available.
Since:
19.0/**
     * Returns the source section location of this trace element. The source section is
     * <code>null</code> if the source location is not available.
     *
     * @since 19.0
     */
    public SourceSection getSourceSection() {
        if (isHost()) {
            return null;
        }
        Node node = traceElement.getLocation();
        if (node != null) {
            return session.resolveSection(node);
        }
        return null;
    }

    
Get the current inner-most scope. The scope might not provide valid information if the
execution path diverges from this trace element.
Returns:
the scope, or null when no language is associated with this frame
        location, or when no local scope exists.
Since:
19.0/**
     * Get the current inner-most scope. The scope might not provide valid information if the
     * execution path diverges from this trace element.
     *
     * @return the scope, or <code>null</code> when no language is associated with this frame
     *         location, or when no local scope exists.
     * @since 19.0
     */
    public DebugScope getScope() {
        if (isHost()) {
            return null;
        }
        Node node = traceElement.getLocation();
        if (node == null) {
            return null;
        }
        RootNode root = node.getRootNode();
        if (root.getLanguageInfo() == null) {
            // no language, no scopes
            return null;
        }
        Frame elementFrame = traceElement.getFrame();
        MaterializedFrame frame = (elementFrame != null) ? elementFrame.materialize() : null;
        if (!NodeLibrary.getUncached().hasScope(node, frame)) {
            return null;
        }
        try {
            Object scope = NodeLibrary.getUncached().getScope(node, frame, true);
            return new DebugScope(scope, session, null, node, frame, root);
        } catch (UnsupportedMessageException e) {
            throw CompilerDirectives.shouldNotReachHere(e);
        }
    }

    private LanguageInfo getLanguage() {
        if (isHost()) {
            return null;
        }
        LanguageInfo language;
        RootNode root = findCurrentRoot();
        if (root != null) {
            language = root.getLanguageInfo();
        } else {
            language = null;
        }
        return language;
    }

    private RootNode findCurrentRoot() {
        if (isHost()) {
            return null;
        }
        Node node = traceElement.getLocation();
        if (node != null) {
            return node.getRootNode();
        }
        RootCallTarget target = traceElement.getTarget();
        return target.getRootNode();
    }

    StackTraceElement toTraceElement() {
        if (stackTraceElement == null) {
            if (hostTraceElement != null) {
                stackTraceElement = hostTraceElement;
            } else {
                LanguageInfo language = getLanguage();
                String declaringClass = language != null ? "<" + language.getId() + ">" : "<unknown>";
                String methodName = getName0();
                if (methodName == null) {
                    methodName = "";
                }
                SourceSection sourceLocation = getSourceSection();
                String fileName = sourceLocation != null ? sourceLocation.getSource().getName() : "Unknown";
                int startLine = sourceLocation != null ? sourceLocation.getStartLine() : -1;
                stackTraceElement = new StackTraceElement(declaringClass, methodName, fileName, startLine);
            }
        }
        return stackTraceElement;
    }
}