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package com.oracle.graal.python.nodes.frame;

import com.oracle.graal.python.builtins.objects.dict.PDict;
import com.oracle.graal.python.builtins.objects.frame.PFrame;
import com.oracle.graal.python.builtins.objects.frame.PFrame.Reference;
import com.oracle.graal.python.builtins.objects.function.PArguments;
import com.oracle.graal.python.builtins.objects.object.PythonObject;
import com.oracle.graal.python.runtime.object.PythonObjectFactory;
import com.oracle.truffle.api.dsl.Cached;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.frame.Frame;
import com.oracle.truffle.api.frame.VirtualFrame;
import com.oracle.truffle.api.nodes.Node;
import com.oracle.truffle.api.profiles.ConditionProfile;

/**
 * Read the locals from the passed frame, updating them from the frame if that is needed. This does
 * <emph>not</emph> let the frame escape.
 **/
public abstract class ReadLocalsNode extends Node {
    public abstract Object execute(VirtualFrame callingFrame, PFrame frame);

    protected static boolean isGeneratorFrame(PFrame frame) {
        return PArguments.isGeneratorFrame(frame.getArguments());
    }

    protected static PFrame getPFrame(Frame frame) {
        Reference frameInfo = PArguments.getCurrentFrameInfo(frame);
        return frameInfo != null ? frameInfo.getPyFrame() : null;
    }

    @Specialization(guards = {"isGeneratorFrame(frame)"})
    static Object doGeneratorFrame(@SuppressWarnings("unused") VirtualFrame callingFrame, PFrame frame) {
        PDict localsDict = PArguments.getGeneratorFrameLocals(frame.getArguments());
        assert localsDict != null : "generator locals dict was not eagerly created";
        return localsDict;
    }

    @Specialization(guards = {"!isGeneratorFrame(frame)"})
    static Object frameToUpdate(PFrame frame,
                    @Cached PythonObjectFactory factory) {
        return frame.getLocals(factory);
    }

    public static ReadLocalsNode create() {
        return ReadLocalsNodeGen.create();
    }

    /**
     * Fast access to custom locals if a custom dict was provided by the caller and the python frame
     * does not escape.
     *
     * @param frame the current frame
     * @param havePyFrame profile if we do have a python frame (PFrame)
     * @param haveCustomLocals profile if the python frame has a custom set locals dict
     * @return the custom locals (if found) or the globals
     */
    public static PythonObject fastGetCustomLocalsOrGlobals(VirtualFrame frame, ConditionProfile havePyFrame, ConditionProfile haveCustomLocals) {
        PFrame pyFrame = PArguments.getCurrentFrameInfo(frame).getPyFrame();
        if (havePyFrame.profile(pyFrame != null) && haveCustomLocals.profile(pyFrame.getLocals(null) != null)) {
            return (PythonObject) pyFrame.getLocals(null);
        }
        // return the globals
        return PArguments.getGlobals(frame);
    }
}
