JDK14/Java14源码在线阅读

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 * accompanied this code).
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package jdk.nashorn.internal.codegen;

import static jdk.nashorn.internal.codegen.CompilerConstants.ARGUMENTS;
import static jdk.nashorn.internal.codegen.CompilerConstants.constructorNoLookup;
import static jdk.nashorn.internal.codegen.CompilerConstants.typeDescriptor;
import static jdk.nashorn.internal.codegen.ObjectClassGenerator.PRIMITIVE_FIELD_TYPE;
import static jdk.nashorn.internal.codegen.ObjectClassGenerator.getFieldName;
import static jdk.nashorn.internal.codegen.ObjectClassGenerator.getPaddedFieldCount;
import static jdk.nashorn.internal.runtime.arrays.ArrayIndex.getArrayIndex;
import static jdk.nashorn.internal.runtime.arrays.ArrayIndex.isValidArrayIndex;

import java.util.List;
import jdk.nashorn.internal.codegen.types.Type;
import jdk.nashorn.internal.ir.Symbol;
import jdk.nashorn.internal.runtime.Context;
import jdk.nashorn.internal.runtime.JSType;
import jdk.nashorn.internal.runtime.PropertyMap;
import jdk.nashorn.internal.runtime.ScriptObject;
import jdk.nashorn.internal.runtime.arrays.ArrayIndex;

/**
 * Analyze an object's characteristics for appropriate code generation. This
 * is used for functions and for objects. A field object take a set of values which
 * to assign to the various fields in the object. This is done by the generated code
 *
 * @param <T> the value type for the fields being written on object creation, e.g. Node
 * @see jdk.nashorn.internal.ir.Node
 */
public abstract class FieldObjectCreator<T> extends ObjectCreator<T> {

    private String                        fieldObjectClassName;
    private Class<? extends ScriptObject> fieldObjectClass;
    private int                           fieldCount;
    private int                           paddedFieldCount;
    private int                           paramCount;

    /** call site flags to be used for invocations */
    private final int callSiteFlags;
    /** are we creating this field object from 'eval' code? */
    private final boolean evalCode;

    /**
     * Constructor
     *
     * @param codegen  code generator
     * @param tuples   tuples for fields in object
     */
    FieldObjectCreator(final CodeGenerator codegen, final List<MapTuple<T>> tuples) {
        this(codegen, tuples, false, false);
    }

    /**
     * Constructor
     *
     * @param codegen      code generator
     * @param tuples       tuples for fields in object
     * @param isScope      is this a scope object
     * @param hasArguments does the created object have an "arguments" property
     */
    FieldObjectCreator(final CodeGenerator codegen, final List<MapTuple<T>> tuples, final boolean isScope, final boolean hasArguments) {
        super(codegen, tuples, isScope, hasArguments);
        this.callSiteFlags = codegen.getCallSiteFlags();
        this.evalCode = codegen.isEvalCode();
        countFields();
        findClass();
    }

    @Override
    public void createObject(final MethodEmitter method) {
        makeMap();
        final String className = getClassName();
        // NOTE: we must load the actual structure class here, because the API operates with Nashorn Type objects,
        // and Type objects need a loaded class, for better or worse. We also have to be specific and use the type
        // of the actual structure class, we can't generalize it to e.g. Type.typeFor(ScriptObject.class) as the
        // exact type information is needed for generating continuations in rest-of methods. If we didn't do this,
        // object initializers like { x: arr[i] } would fail during deoptimizing compilation on arr[i], as the
        // values restored from the RewriteException would be cast to "ScriptObject" instead of to e.g. "JO4", and
        // subsequently the "PUTFIELD J04.L0" instruction in the continuation code would fail bytecode verification.
        assert fieldObjectClass != null;
        method._new(fieldObjectClass).dup();

        loadMap(method); //load the map

        if (isScope()) {
            loadScope(method);

            if (hasArguments()) {
                method.loadCompilerConstant(ARGUMENTS);
                method.invoke(constructorNoLookup(className, PropertyMap.class, ScriptObject.class, ARGUMENTS.type()));
            } else {
                method.invoke(constructorNoLookup(className, PropertyMap.class, ScriptObject.class));
            }
        } else {
            method.invoke(constructorNoLookup(className, PropertyMap.class));
        }
    }

    /**
     * Create a scope for a for-in/of loop as defined in ES6 13.7.5.13 step 5.g.iii
     *
     * @param method the method emitter
     */
    void createForInIterationScope(final MethodEmitter method) {
        assert fieldObjectClass != null;
        assert isScope();
        assert getMap() != null;

        final String className = getClassName();
        method._new(fieldObjectClass).dup();
        loadMap(method); //load the map
        loadScope(method);
        // We create a scope identical to the currently active one, so use its parent as our parent
        method.invoke(ScriptObject.GET_PROTO);
        method.invoke(constructorNoLookup(className, PropertyMap.class, ScriptObject.class));
    }

    @Override
    public void populateRange(final MethodEmitter method, final Type objectType, final int objectSlot, final int start, final int end) {
        method.load(objectType, objectSlot);
        // Set values.
        for (int i = start; i < end; i++) {
            final MapTuple<T> tuple = tuples.get(i);
            //we only load when we have both symbols and values (which can be == the symbol)
            //if we didn't load, we need an array property
            if (tuple.symbol != null && tuple.value != null) {
                final int index = getArrayIndex(tuple.key);
                method.dup();
                if (!isValidArrayIndex(index)) {
                    putField(method, tuple.key, tuple.symbol.getFieldIndex(), tuple);
                } else {
                    putSlot(method, ArrayIndex.toLongIndex(index), tuple);
                }

                //this is a nop of tuple.key isn't e.g. "apply" or another special name
                method.invalidateSpecialName(tuple.key);
            }
        }
    }

    @Override
    protected PropertyMap makeMap() {
        assert propertyMap == null : "property map already initialized";
        propertyMap = newMapCreator(fieldObjectClass).makeFieldMap(hasArguments(), codegen.useDualFields(), fieldCount, paddedFieldCount, evalCode);
        return propertyMap;
    }

    /**
     * Store a value in a field of the generated class object.
     *
     * @param method      Script method.
     * @param key         Property key.
     * @param fieldIndex  Field number.
     * @param tuple       Tuple to store.
     */
    private void putField(final MethodEmitter method, final String key, final int fieldIndex, final MapTuple<T> tuple) {
        final Type    fieldType   = codegen.useDualFields() && tuple.isPrimitive() ? PRIMITIVE_FIELD_TYPE : Type.OBJECT;
        final String  fieldClass  = getClassName();
        final String  fieldName   = getFieldName(fieldIndex, fieldType);
        final String  fieldDesc   = typeDescriptor(fieldType.getTypeClass());

        assert fieldName.equals(getFieldName(fieldIndex, PRIMITIVE_FIELD_TYPE)) || fieldType.isObject() :    key + " object keys must store to L*-fields";
        assert fieldName.equals(getFieldName(fieldIndex, Type.OBJECT))          || fieldType.isPrimitive() : key + " primitive keys must store to J*-fields";

        loadTuple(method, tuple, true);
        method.putField(fieldClass, fieldName, fieldDesc);
    }

    /**
     * Store a value in an indexed slot of a generated class object.
     *
     * @param method Script method.
     * @param index  Slot index.
     * @param tuple  Tuple to store.
     */
    private void putSlot(final MethodEmitter method, final long index, final MapTuple<T> tuple) {
        loadIndex(method, index);
        loadTuple(method, tuple, false); //we don't pack array like objects
        method.dynamicSetIndex(callSiteFlags);
    }

    /**
     * Locate (or indirectly create) the object container class.
     */
    private void findClass() {
        fieldObjectClassName = isScope() ?
                ObjectClassGenerator.getClassName(fieldCount, paramCount, codegen.useDualFields()) :
                ObjectClassGenerator.getClassName(paddedFieldCount, codegen.useDualFields());

        try {
            this.fieldObjectClass = Context.forStructureClass(Compiler.binaryName(fieldObjectClassName));

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