Package org.apache.openjpa.kernel

Class ResultShape<T>

java.lang.Object
org.apache.openjpa.kernel.ResultShape<T>
All Implemented Interfaces:
Serializable
public class ResultShape<T> extends Object implements Serializable
Describes the shape of a query result.
A shape is described as a Java class by the generic type argument T. A shape may contain zero or more shapes. A shape is categorized as follows:
  • A primitive shape can not have child shapes e.g. Foo or float.
  • A compound shape has zero or more child shapes e.g. Foo{} or Foo{String, int} or Foo{String,Bar{Double},int}.
  • A nesting shape has one or more compound child shape(s). For example, Foo{String,Bar{Double},int}. On the other hand, Foo{String, int} is a compound shape but is not nesting because all its child shapes are primitive.
    A primitive category shape is declared during construction and immutable. The category of a non-primitive shape is mutable.
    Notice that all nested shapes are compound shapes but not all compound shapes are nesting.
    A compound shape can add other primitive shapes or nest other shapes to any arbitrary depth. However, a shape does not allow recursive nesting of shapes.
    Usage: The purpose of a shape is to populate an instance of T from an array of input values where each array element is further specified with a type and an alias. FillStrategy determines how a shape populates an instance of T by consuming the input array element values. The input data is presented as an Object[] with a parallel array of types because the primitive types (short, float etc.) are not preserved in the input array. For certain FillStrategy such as MAP or BEAN, the alias of the input array element are used to identify the Map key or setter methods respectively.
    • Since:
    2.0.0
    Author:
    Pinaki Poddar
    See Also:

    • Constructor Details

      • ResultShape

        public ResultShape(Class<T> cls)
        Construct a non-primitive shape with ASSIGN or ARRAY fill strategy.

      • ResultShape

        public ResultShape(Class<T> cls, boolean primitive)
        Construct a primitive or non-primitive shape with ASSIGN or ARRAY fill strategy. If the shape is declared as primitive then the given class can not be an array.

      • ResultShape

        public ResultShape(Class<T> cls, FillStrategy<T> strategy)
        Construct a non-primitive shape with the given fill strategy.

      • ResultShape

        public ResultShape(Class<T> cls, FillStrategy<T> strategy, boolean primitive)
        Construct a shape with the given fill strategy.

    • Method Details

      • getType

        public Class<T> getType()
        Gets the type of instance populated by this shape.

      • getStrategy

        public FillStrategy<T> getStrategy()

      • setAlias

        public ResultShape<T> setAlias(String alias)

      • getAlias

        public String getAlias()

      • getCompositeTypes

        public List<Class<?>> getCompositeTypes()
        Gets the list of classes to compose this shape and all its children. For example, a shape Foo{String,Bar{int, Date}, Double} will return {String, int, Date, Double}

      • getTypes

        public List<Class<?>> getTypes()
        Gets the list of classes to compose this shape only i.e. without expanding the children's shape. For example, a shape Foo{String,Bar{int, Date}, Double} will return {String, Bar, Double}

      • nest

        public <X> ResultShape<X> nest(Class<X> cls, FillStrategy strategy, Class<?>... classes)
        Creates a new shape of type X with the given class arguments and nests the new shape within this shape.
        Returns:
        newly created nested shape

      • nest

        public ResultShape<T> nest(ResultShape<?> shape)
        Nest the given shape.
        Parameters:
        shape - The given shape can not be a parent of this shape to prohibit recursive nesting.
        Returns:
        this shape itself

      • add

        public ResultShape<T> add(Class<?>... classes)
        Adds the given classes as child shapes of this shape. The child shapes are primitive shapes.

      • getChildren

        public List<ResultShape<?>> getChildren()
        Gets all the child shapes.

      • isCompound

        public boolean isCompound()
        Affirms if this shape can have child shapes.

      • isPrimitive

        public boolean isPrimitive()
        Affirms if this shape can not have any child shape. A primitive shape uses ASSIGN strategy.

      • isNesting

        public boolean isNesting()
        Affirms if at least one child shape of this shape is a compound shape.

      • isNested

        public boolean isNested()
        Affirms if this shape is nested within other shapes.

      • isParent

        public boolean isParent(ResultShape<?> p)
        Affirms if the given shape is a parent (or grandparent) of this shape.

      • getParents

        public Set<ResultShape<?>> getParents()
        Gets the immediate parents of this shape.

      • argLength

        public int argLength()
        Total number of arguments required to populate the shape and all its child shapes.

      • length

        public int length()
        Number of arguments to populate this shape only.

      • pack

        public T pack(Object[] values, Class<?>[] types, String[] aliases)
        Fill this shape and its children with the given array element values. The parallel arrays contain the actual values, the types of these values and aliases. The type and alias information are used for packing Map or invoking constructor. The type can be different from what can be determined from array elements because of boxing of primitive types. The actual constructor argument types are sourced from types[] array.

      • toString

        public String toString()
        Gets a human-readable representation of this shape.
        Overrides:
        toString in class Object