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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
Type parameters:
  • <T> – the value type for the fields being written on object creation, e.g. Node
See Also:
/** * 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
/** call site flags to be used for invocations */
private final int callSiteFlags;
are we creating this field object from 'eval' code?
/** are we creating this field object from 'eval' code? */
private final boolean evalCode;
Constructor
Params:
  • codegen – code generator
  • tuples – tuples for fields in object
/** * 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
Params:
  • codegen – code generator
  • tuples – tuples for fields in object
  • isScope – is this a scope object
  • hasArguments – does the created object have an "arguments" property
/** * 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
Params:
  • method – the method emitter
/** * 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.
Params:
  • method – Script method.
  • key – Property key.
  • fieldIndex – Field number.
  • tuple – Tuple to store.
/** * 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.
Params:
  • method – Script method.
  • index – Slot index.
  • tuple – Tuple to store.
/** * 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.
/** * 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)); } catch (final ClassNotFoundException e) { throw new AssertionError("Nashorn has encountered an internal error. Structure can not be created."); } } @Override protected Class<? extends ScriptObject> getAllocatorClass() { return fieldObjectClass; }
Get the class name for the object class, e.g. com.nashorn.oracle.scripts.JO2P0
Returns:script class name
/** * Get the class name for the object class, * e.g. {@code com.nashorn.oracle.scripts.JO2P0} * * @return script class name */
String getClassName() { return fieldObjectClassName; }
Tally the number of fields and parameters.
/** * Tally the number of fields and parameters. */
private void countFields() { for (final MapTuple<T> tuple : tuples) { final Symbol symbol = tuple.symbol; if (symbol != null) { if (hasArguments() && symbol.isParam()) { symbol.setFieldIndex(paramCount++); } else if (!isValidArrayIndex(getArrayIndex(tuple.key))) { symbol.setFieldIndex(fieldCount++); } } } paddedFieldCount = getPaddedFieldCount(fieldCount); } }