Module aeonics.core
Package aeonics.data

Interface Data

  • All Superinterfaces:
    java.lang.Iterable<Data>
    public interface Data
extends java.lang.Iterable<Data>
    Inert representation of mutable data.

    This class has the ability to wrap either an object, or a list of objects, or a key/value map. It can perform basic type coersion with late evaluation principle.

    By default, implementations will try to be as resilient as possible (i.e. convert a string key to an integer for a list) but it may eventually give up and throw a RuntimeException.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static java.util.regex.Pattern nestedSplitter
      Simple pattern that defines '.' or '/' to be a path saparator in other nested-like functions.

    • Method Summary

      All Methods Static Methods Instance Methods Abstract Methods Default Methods 
      Modifier and Type Method Description
      Data add​(java.lang.Object value)
      Adds the provided value to this map or list.
      Data add​(java.lang.Object... value)
      Adds the provided values to this map or list.
      boolean asBool()
      Coerces this data to a boolean.
      default boolean asBool​(int index)
      Coerces the specified element to a boolean.
      default boolean asBool​(java.lang.String key)
      Coerces the mapped value to a boolean.
      default double asDouble()
      Coerces this data to a double as per Number.doubleValue()
      default double asDouble​(int index)
      Coerces the specified element to a double as per Number.doubleValue()
      default double asDouble​(java.lang.String key)
      Coerces the mapped value to a double as per Number.doubleValue()
      default int asInt()
      Coerces this data to an integer as per Number.intValue()
      default int asInt​(int index)
      Coerces the specified element to an integer as per Number.intValue()
      default int asInt​(java.lang.String key)
      Coerces the mapped value to an integer as per Number.intValue()
      default long asLong()
      Coerces this data to a long as per Number.longValue()
      default long asLong​(int index)
      Coerces the specified element to a long as per Number.longValue()
      default long asLong​(java.lang.String key)
      Coerces the mapped value to a long as per Number.longValue()
      java.lang.Number asNumber()
      Coerces this data to a number.
      default java.lang.Number asNumber​(int index)
      Coerces the specified element to a number.
      default java.lang.Number asNumber​(java.lang.String key)
      Coerces the mapped value to a number.
      java.lang.String asString()
      Coerces this data to a string.
      default java.lang.String asString​(int index)
      Coerces the specified element to a string.
      default java.lang.String asString​(java.lang.String key)
      Coerces the mapped value to a string.
      void clear()
      Removes all elements in case of a map or list, or sets the value to null in case of an object
      Data clone()
      Deep clone of this data instance.
      void cloneTo​(Data other)
      Clears and deep clones this data instance into the target data object.
      boolean containsKey​(java.lang.String key)
      Returns true if an object can be fetched with the specified key
      default boolean containsKeyNested​(java.lang.String key)
      Returns true if this data object contains the specified nested key.
      static Data empty()
      Returns a null object data
      java.lang.Iterable<java.util.Map.Entry<java.lang.String,​Data>> entrySet()
      Returns an entry set of this data map.
      default boolean equals​(int index, java.lang.Object other)
      Returns true if the specified element equals the specified object as per get(index).equals(other);
      default boolean equals​(java.lang.String key, java.lang.Object other)
      Returns true if the mapped value equals the specified object as per get(key).equals(other);
      default Data find​(java.util.function.Predicate<Data> predicate)
      Searches this data object and returns the first occurence that match the pattern.
      <T> T get()
      Unwraps the real object value and performs an implicit cast to the receiving type
      Data get​(int index)
      Returns the specified element
      Data get​(java.lang.String key)
      Returns the mapped value
      default Data getNested​(java.lang.String key)
      Returns the nested value matching the specified key.
      default <T> T getOr​(T fallback)
      Unwraps the real object value and performs an implicit cast to the receiving type.
      default boolean is​(int index, java.lang.Class<?> type)
      Returns true if the specified element is an object of the specified type
      boolean is​(java.lang.Class<?> type)
      Returns true of tis data instance is of the specified type
      default boolean is​(java.lang.String key, java.lang.Class<?> type)
      Returns true if the mapped value is an object of the specified type
      boolean isBool()
      Returns true if this data instance is a boolean object
      default boolean isBool​(int index)
      Returns true if the specified element is a boolean object
      default boolean isBool​(java.lang.String key)
      Returns true if the mapped value is a boolean object
      boolean isEmpty()
      Returns true if this data instance is null, blank, an empty list or an empty map
      default boolean isEmpty​(int index)
      Returns true if the specified element is a null object, blank or empty
      default boolean isEmpty​(java.lang.String key)
      Returns true if the mapped value is a a null object, blank or empty
      boolean isList()
      Returns true if this data instance is a list
      default boolean isList​(int index)
      Returns true if the specified element is a list itself
      default boolean isList​(java.lang.String key)
      Returns true if the mapped value is a list
      boolean isMap()
      Returns true if this data instance is a map
      default boolean isMap​(int index)
      Returns true if the specified element is a map
      default boolean isMap​(java.lang.String key)
      Returns true if the mapped value is a map itself
      boolean isNull()
      Returns true of this data instance is a null object
      default boolean isNull​(int index)
      Returns true if the specified element is a null object
      default boolean isNull​(java.lang.String key)
      Returns true if the mapped value is a null object
      boolean isNumber()
      Returns true if this data instance is a number type object
      default boolean isNumber​(int index)
      Returns true if the specified element is a number type
      default boolean isNumber​(java.lang.String key)
      Returns true if the mapped value is a number type
      boolean isString()
      Returns true if this data instance is a string object
      default boolean isString​(int index)
      Returns true if the specified element is a string object
      default boolean isString​(java.lang.String key)
      Returns true if the mapped value is a string object
      java.util.Iterator<Data> iterator()
      Returns an iterator over the elements of this list of data, or over the values of the map.
      static Data list()
      Returns an empty data list
      static Data list​(java.lang.Object... elements)
      Returns a data list from the specified elements
      static Data map()
      Returns an empty data map
      static Data of​(java.lang.Object item)
      Wraps the specified object in a data structure
      Data put​(java.lang.String key, java.lang.Object value)
      Adds the provided value to this map or list.
      default Data putNested​(java.lang.String key, java.lang.Object value)
      Adds the provided nested value ot this map or list.
      Data remove​(int index)
      Removes the specified element and returns it.
      Data remove​(Data item)
      Removes the value if it exists and returns it.
      Data remove​(java.lang.String key)
      Removes the mapped element and returns it
      void removeIf​(java.util.function.Predicate<Data> check)
      Removes the value if the value if this map or list matches the predicate.
      default Data removeNested​(java.lang.String key)
      Removes the nested element and returns it.
      Data set​(int index, java.lang.Object value)
      Sets the value at the specified index
      Data set​(java.lang.Object value)
      Swaps the underlying value entirely.
      int size()
      Returns the number of element in case of map or list, or 1 for an object

      • Methods inherited from interface java.lang.Iterable

        forEach, spliterator

    • Method Detail

      • of

        static Data of​(java.lang.Object item)
        Wraps the specified object in a data structure
        Parameters:
        item - the object to wrap
        Returns:
        a data representation

      • empty

        static Data empty()
        Returns a null object data
        Returns:
        a null object data

      • map

        static Data map()
        Returns an empty data map
        Returns:
        an empty data map

      • list

        static Data list()
        Returns an empty data list
        Returns:
        an empty data list

      • list

        static Data list​(java.lang.Object... elements)
        Returns a data list from the specified elements
        Parameters:
        elements - the list of elements
        Returns:
        a data list from the specified elements

      • iterator

        java.util.Iterator<Data> iterator()
        Returns an iterator over the elements of this list of data, or over the values of the map. If this data instance is a regular object, then this method returns an iterator over itself.
        Specified by:
        iterator in interface java.lang.Iterable<Data>
        Returns:
        an iterator over the elements

      • entrySet

        java.lang.Iterable<java.util.Map.Entry<java.lang.String,​Data>> entrySet()
        Returns an entry set of this data map. If this data instance is not a map, an empty set is returned.
        Returns:
        an entry set of this data

      • isMap

        boolean isMap()
        Returns true if this data instance is a map
        Returns:
        true if this data instance is a map

      • isList

        boolean isList()
        Returns true if this data instance is a list
        Returns:
        true if this data instance is a list

      • isBool

        boolean isBool()
        Returns true if this data instance is a boolean object
        Returns:
        true if this data instance is a boolean object

      • isNumber

        boolean isNumber()
        Returns true if this data instance is a number type object
        Returns:
        true if this data instance is a number type object

      • isString

        boolean isString()
        Returns true if this data instance is a string object
        Returns:
        true if this data instance is a string object

      • isNull

        boolean isNull()
        Returns true of this data instance is a null object
        Returns:
        true of this data instance is a null object

      • is

        boolean is​(java.lang.Class<?> type)
        Returns true of tis data instance is of the specified type
        Parameters:
        type - the object type
        Returns:
        true of tis data instance is of the specified type

      • isEmpty

        boolean isEmpty()
        Returns true if this data instance is null, blank, an empty list or an empty map
        Returns:
        true if this data instance is null, blank, an empty list or an empty map

      • isMap

        default boolean isMap​(java.lang.String key)
        Returns true if the mapped value is a map itself
        Parameters:
        key - the key to check
        Returns:
        true if the mapped value is a map itself
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • isList

        default boolean isList​(java.lang.String key)
        Returns true if the mapped value is a list
        Parameters:
        key - the key to check
        Returns:
        true if the mapped value is a list
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • isBool

        default boolean isBool​(java.lang.String key)
        Returns true if the mapped value is a boolean object
        Parameters:
        key - the key to check
        Returns:
        true if the mapped value is a boolean object
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • isNumber

        default boolean isNumber​(java.lang.String key)
        Returns true if the mapped value is a number type
        Parameters:
        key - the key to check
        Returns:
        true if the mapped value is a number type
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • isString

        default boolean isString​(java.lang.String key)
        Returns true if the mapped value is a string object
        Parameters:
        key - the key to check
        Returns:
        true if the mapped value is a string object
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • isNull

        default boolean isNull​(java.lang.String key)
        Returns true if the mapped value is a null object
        Parameters:
        key - the key to check
        Returns:
        true if the mapped value is a null object
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • isEmpty

        default boolean isEmpty​(java.lang.String key)
        Returns true if the mapped value is a a null object, blank or empty
        Parameters:
        key - the key to check
        Returns:
        true if the mapped value is a null object, blank or empty
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • is

        default boolean is​(java.lang.String key,
                   java.lang.Class<?> type)
        Returns true if the mapped value is an object of the specified type
        Parameters:
        key - the key to check
        type - the expected class type
        Returns:
        true if the mapped value is an object of the specified type
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • isMap

        default boolean isMap​(int index)
        Returns true if the specified element is a map
        Parameters:
        index - the element index
        Returns:
        true if the specified element is a map
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • isList

        default boolean isList​(int index)
        Returns true if the specified element is a list itself
        Parameters:
        index - the element index
        Returns:
        true if the specified element is a list itself
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • isBool

        default boolean isBool​(int index)
        Returns true if the specified element is a boolean object
        Parameters:
        index - the element index
        Returns:
        true if the specified element is a boolean object
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • isNumber

        default boolean isNumber​(int index)
        Returns true if the specified element is a number type
        Parameters:
        index - the element index
        Returns:
        true if the specified element is a number type
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • isString

        default boolean isString​(int index)
        Returns true if the specified element is a string object
        Parameters:
        index - the element index
        Returns:
        true if the specified element is a string object
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • isNull

        default boolean isNull​(int index)
        Returns true if the specified element is a null object
        Parameters:
        index - the element index
        Returns:
        true if the specified element is a null object
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • isEmpty

        default boolean isEmpty​(int index)
        Returns true if the specified element is a null object, blank or empty
        Parameters:
        index - the element index
        Returns:
        true if the specified element is a null object, blank or empty
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • is

        default boolean is​(int index,
                   java.lang.Class<?> type)
        Returns true if the specified element is an object of the specified type
        Parameters:
        index - the element index
        type - the expected class type
        Returns:
        true if the specified element is an object of the specified type
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • asBool

        boolean asBool()
        Coerces this data to a boolean. Case invariant "true" or "yes", numeric value 0 and boolean value true all return true. If map or list, returns true if not empty.
        Returns:
        this data as a boolean

      • asString

        java.lang.String asString()
        Coerces this data to a string. Null is converted to an empty string, otherwise the toString() representation. If map or list, returns the JSON representation.
        Returns:
        this data as a string

      • asNumber

        java.lang.Number asNumber()
        Coerces this data to a number. Native numeric value, boolean as 0 or 1, null as 0, string parsed to a long or double, or the object hashCode() . If map or list, returns the number of elements.
        Returns:
        this data as a number

      • asInt

        default int asInt()
        Coerces this data to an integer as per Number.intValue()
        Returns:
        this data as an integer
        See Also:
        asNumber()

      • asLong

        default long asLong()
        Coerces this data to a long as per Number.longValue()
        Returns:
        this data as a long
        See Also:
        asNumber()

      • asDouble

        default double asDouble()
        Coerces this data to a double as per Number.doubleValue()
        Returns:
        this data as a double
        See Also:
        asNumber()

      • asBool

        default boolean asBool​(java.lang.String key)
        Coerces the mapped value to a boolean. Case invariant "true" or "yes", numeric value 0 and boolean value true all return true. If map or list, returns true if not empty.
        Parameters:
        key - the key to check
        Returns:
        the mapped value as a boolean
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • asString

        default java.lang.String asString​(java.lang.String key)
        Coerces the mapped value to a string. Null is converted to an empty string, otherwise the toString() representation. If map or list, returns the JSON representation.
        Parameters:
        key - the key to check
        Returns:
        the mapped value as a string
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • asNumber

        default java.lang.Number asNumber​(java.lang.String key)
        Coerces the mapped value to a number. Native numeric value, boolean as 0 or 1, null as 0, string parsed to a long or double, or the object hashCode() . If map or list, returns the number of elements.
        Parameters:
        key - the key to check
        Returns:
        the mapped value as a number
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • asInt

        default int asInt​(java.lang.String key)
        Coerces the mapped value to an integer as per Number.intValue()
        Parameters:
        key - the key to check
        Returns:
        the mapped value as an integer
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list
        See Also:
        asNumber(String)

      • asLong

        default long asLong​(java.lang.String key)
        Coerces the mapped value to a long as per Number.longValue()
        Parameters:
        key - the key to check
        Returns:
        the mapped value as a long
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list
        See Also:
        asNumber(String)

      • asDouble

        default double asDouble​(java.lang.String key)
        Coerces the mapped value to a double as per Number.doubleValue()
        Parameters:
        key - the key to check
        Returns:
        the mapped value as a double
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list
        See Also:
        asNumber(String)

      • asBool

        default boolean asBool​(int index)
        Coerces the specified element to a boolean. Case invariant "true" or "yes", numeric value 0 and boolean value true all return true. If map or list, returns true if not empty.
        Parameters:
        index - the element index
        Returns:
        the specified element as a boolean
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • asString

        default java.lang.String asString​(int index)
        Coerces the specified element to a string. Null is converted to an empty string, otherwise the toString() representation. If map or list, returns the JSON representation.
        Parameters:
        index - the element index
        Returns:
        the specified element as a string
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • asNumber

        default java.lang.Number asNumber​(int index)
        Coerces the specified element to a number. Native numeric value, boolean as 0 or 1, null as 0, string parsed to a long or double, or the object hashCode() . If map or list, returns the number of elements.
        Parameters:
        index - the element index
        Returns:
        the specified element as a number
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • asInt

        default int asInt​(int index)
        Coerces the specified element to an integer as per Number.intValue()
        Parameters:
        index - the element index
        Returns:
        the specified element as an integer
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list
        See Also:
        asNumber(int)

      • asLong

        default long asLong​(int index)
        Coerces the specified element to a long as per Number.longValue()
        Parameters:
        index - the element index
        Returns:
        the specified element as a long
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list
        See Also:
        asNumber(int)

      • asDouble

        default double asDouble​(int index)
        Coerces the specified element to a double as per Number.doubleValue()
        Parameters:
        index - the element index
        Returns:
        the specified element as a double
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list
        See Also:
        asNumber(int)

      • equals

        default boolean equals​(java.lang.String key,
                       java.lang.Object other)
        Returns true if the mapped value equals the specified object as per get(key).equals(other);
        Parameters:
        key - the key to check
        other - the value to compare
        Returns:
        true if the mapped value equals the specified object

      • equals

        default boolean equals​(int index,
                       java.lang.Object other)
        Returns true if the specified element equals the specified object as per get(index).equals(other);
        Parameters:
        index - the element index
        other - the value to compare
        Returns:
        true if the specified element equals the specified object

      • get

        Data get​(java.lang.String key)
        Returns the mapped value
        Parameters:
        key - the element key
        Returns:
        the mapped value
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • get

        Data get​(int index)
        Returns the specified element
        Parameters:
        index - the element index
        Returns:
        the specified element
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • get

        <T> T get()
        Unwraps the real object value and performs an implicit cast to the receiving type
        Type Parameters:
        T - the receiving type
        Returns:
        the real object value

      • containsKey

        boolean containsKey​(java.lang.String key)
        Returns true if an object can be fetched with the specified key
        Parameters:
        key - the element key
        Returns:
        true if an object can be fetched with the specified key
        See Also:
        get(String)

      • find

        default Data find​(java.util.function.Predicate<Data> predicate)
        Searches this data object and returns the first occurence that match the pattern.
        Parameters:
        predicate - the test function
        Returns:
        the first matching element, or null if not found

      • getOr

        default <T> T getOr​(T fallback)
        Unwraps the real object value and performs an implicit cast to the receiving type. If the real object value is null, the provided fallback value is returned instead
        Type Parameters:
        T - the receiving type
        Parameters:
        fallback - the fallback value in case the real object value is null
        Returns:
        the real object value or the fallback value in case of null

      • clear

        void clear()
        Removes all elements in case of a map or list, or sets the value to null in case of an object

      • size

        int size()
        Returns the number of element in case of map or list, or 1 for an object
        Returns:
        the number of element in case of map or list, or 1 for an object

      • remove

        Data remove​(java.lang.String key)
        Removes the mapped element and returns it
        Parameters:
        key - the element key
        Returns:
        the previously mapped element, or null if there was no mapping for the key
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • remove

        Data remove​(int index)
        Removes the specified element and returns it. The remaining elements are shifted and the size is reduced by 1.
        Parameters:
        index - the element index
        Returns:
        the removed element
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • remove

        Data remove​(Data item)
        Removes the value if it exists and returns it.
        Parameters:
        item - the value to remove
        Returns:
        the removed value
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • removeIf

        void removeIf​(java.util.function.Predicate<Data> check)
        Removes the value if the value if this map or list matches the predicate.
        Parameters:
        check - the comparison function
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • add

        Data add​(java.lang.Object value)
        Adds the provided value to this map or list. If this data instance is a map, the value will be mapped to an empty key
        Parameters:
        value - the value to add
        Returns:
        this for chaining
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • add

        Data add​(java.lang.Object... value)
        Adds the provided values to this map or list. If this data instance is a map, every even value is the key and odd the value.
        Parameters:
        value - the value to add
        Returns:
        this for chaining
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • put

        Data put​(java.lang.String key,
         java.lang.Object value)
        Adds the provided value to this map or list.
        Parameters:
        key - the element key
        value - the value to add
        Returns:
        this for chaining
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • set

        Data set​(int index,
         java.lang.Object value)
        Sets the value at the specified index
        Parameters:
        index - the element index
        value - the value to set
        Returns:
        this for chaining
        Throws:
        java.lang.RuntimeException - if this data instance is not a map or a list

      • set

        Data set​(java.lang.Object value)
        Swaps the underlying value entirely. If this data instance is a list, add(value) is used instead. If this data instance is a map, put("", value) is used instead.
        Parameters:
        value - the new value
        Returns:
        this for chaining

      • clone

        Data clone()
        Deep clone of this data instance. In case of a map or list, all contained elements are also deep cloned. In case of a non-simple (String, int,...) value object, then the object is referenced and not duplicated.
        Returns:
        a new deep copy of this data instance

      • cloneTo

        void cloneTo​(Data other)
        Clears and deep clones this data instance into the target data object.
        Parameters:
        other - the target data object to copy to
        Throws:
        java.lang.IllegalArgumentException - if the destination data object is not the same type as this instance (map, list or object)

      • getNested

        default Data getNested​(java.lang.String key)
        Returns the nested value matching the specified key. The key should be a dot, forward slash or back slash ('./\') separated list of sub-keys to fetch.

        The key foo.bar.key will fetch the foo object, then fetch the bar object from it, then return the key mapped value.

        If this data object is not a list or a map, or if the key does not map to a value, then an empty data is returned.

        Parameters:
        key - the nested key
        Returns:
        the nested value associated with the key or an empty data object if not found
        See Also:
        get(String)

      • containsKeyNested

        default boolean containsKeyNested​(java.lang.String key)
        Returns true if this data object contains the specified nested key. The key should be a dot, forward slash or back slash ('./\') separated list of sub-keys to fetch.

        The key foo.bar.key will fetch the foo object, then fetch the bar object from it, then return if the key exists.

        If this data object is not a list or a map, or if the key does not map to a value, then this method returns false.

        Parameters:
        key - the nested key
        Returns:
        true if this data object contains the specified nested key
        See Also:
        containsKey(String)

      • putNested

        default Data putNested​(java.lang.String key,
                       java.lang.Object value)
        Adds the provided nested value ot this map or list. The key should be a dot, forward slash or back slash ('./\') separated list of sub-keys to fetch.

        The key foo.bar.key will fetch the foo object, then fetch the bar object from it, then set the value for the key.

        Missing intermediate objects are created automatically.

        Parameters:
        key - the nested key
        value - the value to add
        Returns:
        this top level object for chaining
        See Also:
        put(String, Object)

      • removeNested

        default Data removeNested​(java.lang.String key)
        Removes the nested element and returns it. The key should be a dot, forward slash or back slash ('./\') separated list of sub-keys to fetch.

        The key foo.bar.key will fetch the foo object, then fetch the bar object from it, then remove the value mapped to the key.

        Parameters:
        key - the nested key
        Returns:
        the previously mapped element, or null if there was no mapping for the nested key
        See Also:
        remove(String)