Module swim.structure

Package swim.structure.form

Class ClassForm<T>

java.lang.Object

swim.structure.Form<T>

swim.structure.form.ClassForm<T>

All Implemented Interfaces:

Cloneable

public final class ClassForm<T>
extends Form<T>
implements Cloneable

For some Class, a transformation between a structurally typed Item and an instance of that Class.

A Class instance in Java can be completely described by its Class name, its field names, and its field values. This, combined with the fact that some fields are more important than others, gives rise to the following rules for transforming objects into structured Items:

1. The String identifier for the Class, usually simply the Class name or some function of it, is called tag.
2. Every field being considered is either a member or a header, with the latter reserved for "important" fields.
3. Every such field transforms to a Slot whose key is the name of the field and whose value is the Item representation of the field.
4. The structural representation of every object is some Record unless the item is null, which always transforms into Extant.
5. The first entry in this Record is an Attr whose key is tag and whose value is either:
   • A Record of headers that were transformed into Slots via rule 3., or
   • Extant if this Class has no fields.
6. Every subsequent entry in the Record from rule 4. is a member that was transformed into a Slot via rule 3.

These rules can be directly inverted to transform Items to objects.

Constructor Summary

Constructors

Constructor	Description
ClassForm(Class<?> type, String tag, T unit)

Method Summary

Modifier and Type	Method	Description
ClassForm<T>	addHeader(Form<T> header)
ClassForm<T>	addMember(Form<T> member)
T	cast(Item item)	Converts a structurally typed item into a nominally typed Java object.
T	cast(Item item, T object)	Converts a structurally typed item into a nominally typed Java object based on the provided prototype object.
ClassForm<T>	clone()
Item	mold(T object)	Converts a nominally typed Java object into its structurally typed equivalent.
Item	mold(T object, Item item)	Converts a nominally typed Java object into its structurally typed equivalent based on the provided prototype item.
ClassForm<T>	putHeader(String name, Form<?> form)
ClassForm<T>	putHeader(String name, Value key, Form<?> form)
ClassForm<T>	putHeader(Form<T> header)
ClassForm<T>	putMember(String name, Form<?> form)
ClassForm<T>	putMember(String name, Value key, Form<?> form)
ClassForm<T>	putMember(Form<T> member)
String	tag()	Returns the key of the tag attribute that distinguishes structures of this Form; returns null if this Form has no distinguishing tag attribute.
ClassForm<T>	tag(String tag)	Returns a version of this Form that requires a head Attr with the given tag name.
Class<?>	type()	Returns the reified Class of type T.
T	unit()	Returns a default–possibly null–value of type T.
ClassForm<T>	unit(T unit)	Returns a version of this Form with the given unit value.

Methods inherited from class swim.structure.Form

forArray, forBigInteger, forBoolean, forBuiltin, forByte, forByteBuffer, forCharacter, forClass, forClass, forCollection, forDouble, forFloat, forInteger, forItem, forList, forLong, forMap, forMap, forNumber, forSet, forShort, forString, forValue, isBuiltin

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ClassForm

public ClassForm(Class<?> type,
                 String tag,
                 T unit)

Method Detail

tag

public String tag()

Description copied from class: Form

Returns the key of the tag attribute that distinguishes structures of this Form; returns null if this Form has no distinguishing tag attribute. Used to accelerate distrcrimination of polymorphic structural types with nominal type hints.

Overrides:

tag in class Form<T>

tag

public ClassForm<T> tag(String tag)

Description copied from class: Form

Returns a version of this Form that requires a head Attr with the given tag name.

Overrides:

tag in class Form<T>

unit

public T unit()

Description copied from class: Form

Returns a default–possibly null–value of type T. Used as the fallback return value when coercing an invalid structural value.

Overrides:

unit in class Form<T>

unit

public ClassForm<T> unit(T unit)

Description copied from class: Form

Returns a version of this Form with the given unit value.

Overrides:

unit in class Form<T>

addHeader

public ClassForm<T> addHeader(Form<T> header)

putHeader

public ClassForm<T> putHeader(Form<T> header)

putHeader

public ClassForm<T> putHeader(String name,
                              Value key,
                              Form<?> form)

putHeader

public ClassForm<T> putHeader(String name,
                              Form<?> form)

addMember

public ClassForm<T> addMember(Form<T> member)

putMember

public ClassForm<T> putMember(Form<T> member)

putMember

public ClassForm<T> putMember(String name,
                              Value key,
                              Form<?> form)

putMember

public ClassForm<T> putMember(String name,
                              Form<?> form)

type

public Class<?> type()

Description copied from class: Form

Returns the reified Class of type T.

Specified by:

type in class Form<T>

mold

public Item mold(T object,
                 Item item)

Description copied from class: Form

Converts a nominally typed Java object into its structurally typed equivalent based on the provided prototype item. The passed-in item is assumed to be non-null. The returned Item must never be null.

Overrides:

mold in class Form<T>

mold

public Item mold(T object)

Description copied from class: Form

Converts a nominally typed Java object into its structurally typed equivalent. The returned Item must never be null.

Specified by:

mold in class Form<T>

cast

public T cast(Item item,
              T object)

Description copied from class: Form

Converts a structurally typed item into a nominally typed Java object based on the provided prototype object. The passed-in item is assumed to be non-null. The passed-in prototype object may be null.

Overrides:

cast in class Form<T>

cast

public T cast(Item item)

Description copied from class: Form

Converts a structurally typed item into a nominally typed Java object. The passed-in item is assumed to be non-null.

Specified by:

cast in class Form<T>

clone

public ClassForm<T> clone()

Overrides:

clone in class Object