Atom Descriptor
An atom is an object that has identity by fiat, i.e., it is distinguished from all other objects by the fact of its creation event and the history of what happens to its references. Not all objects in Avail have that property (hence the acronym Advanced Value And Identity Language), unlike most object-oriented programming languages.
When an atom is created, a string is supplied to act as the atom's name. This name does not have to be unique among atoms, and is simply used to describe the atom textually.
Atoms fill the role of enumerations commonly found in other languages. They're not the only things that can fill that role, but they're a simple way to do so. In particular, enumerations and multiply polymorphic method dispatch provide a phenomenally powerful technique when combined with atoms. A collection of atoms, say named red, green, and blue, are added to a set from which an enumeration is then constructed. Such a type has exactly three instances: the three atoms. Unlike the vast majority of languages that support enumerations, Avail allows one to define another enumeration containing the same three values plus yellow, cyan, and magenta. red is a member of both enumerations, for example.
Booleans are implemented with exactly this technique, with an atom representing true and another representing false. The boolean type itself is merely an enumeration of these two values. The only thing special about booleans is that they are referenced by the Avail virtual machine. In fact, this very class, AtomDescriptor, contains these references in trueObject and falseObject.
Author
Mark van Gulik
Todd L Smith
See also
Parameters
The mutability of the new descriptor.
The TypeTag to embed in the new descriptor.
The Java Class which is a subclass of ObjectSlotsEnum and defines this object's object slots layout, or null if there are no object slots.
The Java Class which is a subclass of IntegerSlotsEnum and defines this object's object slots layout, or null if there are no integer slots.
Types
The layout of integer slots for my instances.
The layout of object slots for my instances.
SpecialAtom enumerates atoms that are known to the virtual machine.
Functions
Ensure that the specified field is writable.
Create a new object whose descriptor is the receiver, and which has the specified number of indexed (variable) slots.
Create a new object whose descriptor is the receiver, and which has the specified number of indexed (variable) slots.
Create a new object whose descriptor is the receiver, and which has the specified number of indexed (variable) slots.
Can an object using this descriptor have more than the minimum number of integer slots?
Can an object using this descriptor have more than the minimum number of object slots?
Answer the immutable version of this descriptor.
Answer how many levels of printing to allow before elision.
Answer the mutable version of this descriptor.
Answer whether the argument types supported by the specified FunctionTypeDescriptor are acceptable argument types for invoking a FunctionDescriptor whose type is self.
Answer whether these are acceptable TypeDescriptor for invoking a FunctionDescriptor whose type is self.
Answer whether these are acceptable arguments for invoking a FunctionDescriptor whose type is self.
Answer whether these are acceptable TypeDescriptor for invoking a FunctionDescriptor that is an instance of self. There may be more entries in the TupleDescriptor than are required by the FunctionTypeDescriptor.
Answer whether these are acceptable arguments for invoking a FunctionDescriptor that is an instance of self. There may be more entries in the TupleDescriptor than are required by the FunctionTypeDescriptor.
Record the fact that the given L2Chunk depends on the object not changing in some way peculiar to the kind of object. Most typically, this is applied to A_Methods, triggering invalidation if A_Definitions are added to or removed from the method, but at some point we may also support slowly-changing variables.
Add the operands and answer the result.
Add the operands and answer the result.
Construct a Java string from the given Avail StringDescriptor.
Construct a Java set from the given TupleDescriptor.
Construct a TupleDescriptor from the given SetDescriptor. Element ordering in the tuple will be arbitrary and unstable.
Visit my child phrases with the action.
Map my children through the (destructive) transformation specified by aBlock.
Compare a subrange of the receiver with a subrange of the given TupleDescriptor. The size of the subrange of both objects is determined by the index range supplied for the receiver.
Compare a subrange of the receiver with a subrange of the given ByteStringDescriptor. The size of the subrange of both objects is determined by the index range supplied for the receiver.
Compare a subrange of the receiver with a subrange of the given ByteTupleDescriptor. The size of the subrange of both objects is determined by the index range supplied for the receiver.
Compare a subrange of the receiver with a subrange of the given IntegerIntervalTupleDescriptor. The size of the subrange of both objects is determined by the index range supplied for the receiver.
Compare a subrange of the receiver with a subrange of the given NybbleTupleDescriptor. The size of the subrange of both objects is determined by the index range supplied for the receiver.
Compare a subrange of the receiver with a subrange of the given ObjectTupleDescriptor. The size of the subrange of both objects is determined by the index range supplied for the receiver.
Compare a subrange of the receiver with a subrange of the given RepeatedElementTupleDescriptor. The size of the subrange of both objects is determined by the index range supplied for the receiver.
Compare a subrange of the receiver with a subrange of the given SmallIntegerIntervalTupleDescriptor. The size of the subrange of both objects is determined by the index range supplied for the receiver.
Compare a subrange of the receiver with a subrange of another object. The size of the subrange of both objects is determined by the index range supplied for the receiver.
Compare a subrange of the receiver with a subrange of the given TwoByteStringDescriptor. The size of the subrange of both objects is determined by the index range supplied for the receiver.
Compute this object's TypeTag, having failed to extract it from the descriptor directly in AvailObjectRepresentation.typeTag.
Answer a fiber's internal debug log.
Describe the object for the IntelliJ debugger.
Divide the operands and answer the result.
Divide the operands and answer the result.
Answer whether the arguments, both objects, are equal in value.
Answer whether the arguments, an object and a TupleDescriptor, are equal in value.
Answer whether the arguments, an object and a ByteStringDescriptor, are equal in value.
Answer whether the arguments, an object, and a ByteTupleDescriptor, are equal in value.
Answer whether the receiver, an object, is a character with a code point equal to the integer argument.
Answer whether the arguments, an object and a CompiledCodeDescriptor, are equal.
Answer whether the arguments, an object and a FiberTypeDescriptor, are equal in value.
Answer whether the arguments, an object and a FunctionDescriptor, are equal in value.
Answer whether the arguments, an object and a FunctionTypeDescriptor, are equal.
Extract a 64-bit signed Java long from the specified Avail integer.
This atom has no properties, so always answer nil.
Answer whether the receiver contains the specified element.
Is the specified AvailObject an Avail atom?
Given two objects that are known to be equal, is the first one in a better form (more compact, more efficient, older generation) than the second one?
Sets only use explicit bins for collisions, otherwise they store the element itself. This works because a bin can't be an element of a set.
Is the specified AvailObject an Avail boolean?
Is the specified AvailObject an Avail byte tuple?
Is the specified AvailObject an Avail character?
Is the specified AvailObject an Avail extended integer?
Is the specified AvailObject an Avail function?
Is the specified AvailObject an Avail map?
Is the specified AvailObject an Avail nybble?
Is the specified AvailObject an Avail set?
Is the specified AvailObject an Avail string?
Is the specified AvailObject an Avail tuple?
Is the specified AvailObject an Avail unsigned byte?
Answer a pojo's java object. The type is not statically checkable in Java, but at least making it generic avoids an explicit cast expression at each call site.
Given that the receiver is marked immutable, but its slots have not yet been made immutable, scan them now. For each slot found to be mutable, mark it immutable and add it to the supplied list.
Convert to use an AtomWithPropertiesSharedDescriptor, replacing self with an indirection.
{@inheritDoc}
{@inheritDoc}
Add a DefinitionDescriptor to the receiver. Causes dependent chunks to be invalidated.
Difference the operands and answer the result.
Add a GrammaticalRestrictionDescriptor to the receiver.
Multiply the operands and answer the result.
Multiply the operands and answer the result.
Answer how many arguments my instances expect. This is applicable to both MethodDescriptor and CompiledCodeDescriptor.
Add the operands and answer the result.
Given two objects that are known to be equal, the second of which is in the form of a tuple type, is the first one in a better form than the second one?
Return the MethodDescriptor's TupleDescriptor of FunctionDescriptor that statically restrict call sites by argument type.
Convert myself to an equivalent atom with properties, then add the property to it.
Difference the operands and answer the result.
Difference the operands and answer the result.
Multiply the operands and answer the result.
Print the object to the StringBuilder. By default show it as the descriptor's name and a line-by-line list of fields. If the indent is beyond the maximumIndent, indicate it's too deep without recursing. If the object is in the specified recursion list, indicate a recursive print and return.
Throw an AvailUnsupportedOperationException suitable to be thrown by the sender.
Properties
A Statistic that records the number and size of each allocation.
Used for quickly checking integer fields when AvailObjectRepresentation.shouldCheckSlots is enabled.
Used for quickly checking object fields when AvailObjectRepresentation.shouldCheckSlots is enabled.
The minimum number of integer slots an AvailObject can have if it uses this descriptor. Does not include indexed slots possibly at the end. Populated automatically by the constructor.
The minimum number of object slots an AvailObject can have if it uses this descriptor. Does not include indexed slots possibly at the end. Populated automatically by the constructor.
This read-only property can be used in place of unsupportedOperation. Using the getter produces almost the same diagnostic stack trace when executed, but is a much shorter expression.