Module swim.structure
Package swim.structure

Class Item

java.lang.Object
swim.structure.Item
All Implemented Interfaces:
Comparable<Item>, Iterable<Item>, Debug, Display
Direct Known Subclasses:
Field, Value
public abstract class Item extends Object implements Comparable<Item>, Iterable<Item>, Debug, Display

  • Method Details

    • isDefined

      public abstract boolean isDefined()
      Returns true if this Item is not Absent.

    • isDistinct

      public abstract boolean isDistinct()
      Returns true if this Item is neither Extant nor Absent.

    • isDefinite

      public abstract boolean isDefinite()
      Returns true if this Item is not one of: an empty Record, False, Extant, or Absent.

    • isConstant

      public abstract boolean isConstant()
      Returns true if this Item always evaluates to the same Item.

    • key

      public abstract Value key()
      Returns the key component of this Item, if this Item is a Field; otherwise returns Absent if this Item is a Value.

    • toValue

      public abstract Value toValue()
      Returns the value component of this Item, if this Item is a Field; otherwise returns this if this Item is a Value.

    • tag

      public abstract String tag()
      Returns the key string of the first member of this Item, if this Item is a Record, and its first member is an Attr; otherwise returns null if this Item is not a Record, or if this Item is a Record whose first member is not an Attr.

      Used to concisely get the name of the discriminating attribute of a structure. The tag can be used to discern the nominal type of a polymorphic structure, similar to an XML element tag.

    • target

      public abstract Value target()
      Returns the flattened members of this Item after all attributes have been removed, if this Item is a Record; otherwise returns this if this Item is a non-Record Value, or returns the value component if this Item is a Field.

      Used to concisely get the scalar value of an attributed structure. An attributed structure is a Record with one or more attributes that modify one or more other members.

    • flattened

      public abstract Value flattened()
      Returns the sole member of this Item, if this Item is a Record with exactly one member, and its member is a Value; returns Extant if this Item is an empty Record; returns Absent if this Item is a Field; otherwise returns this if this Item is a Record with more than one member, or if this Item is a non-Record Value.

      Used to convert a unary Record into its member Value. Facilitates writing code that treats a unary Record equivalently to a bare Value.

    • unflattened

      public abstract Record unflattened()
      Returns this if this Item is a Record; returns a Record containing just this Item, if this Item is distinct; otherwise returns an empty Record if this Item is Extant or Absent. Facilitates writing code that treats a bare Value equivalently to a unary Record.

    • header

      public abstract Value header(String tag)
      Returns the value of the first member of this Item, if this Item is a Record, and its first member is an Attr whose key string is equal to tag; otherwise returns Absent if this Item is not a Record, or if this Item is a Record whose first member is not an Attr, or if this Item is a Record whose first member is an Attr whose key does not equal the tag.

      Used to conditionally get the value of the head Attr of a structure, if and only if the key string of the head Attr is equal to the tag. Can be used to check if a structure might conform to a nominal type named tag, while simultaneously getting the value of the tag attribute.

    • headers

      public abstract Record headers(String tag)
      Returns the unflattened header of this Item, if this Item is a Record, and its first member is an Attr whose key string is equal to tag; otherwise returns null.

      The headers of the tag attribute of a structure are like the attributes of an XML element tag; through unlike an XML element, tag attribute headers are not limited to string keys and values.

    • head

      public abstract Item head()
      Returns the first member of this Item, if this Item is a non-empty Record; otherwise returns Absent.

    • tail

      public abstract Record tail()
      Returns a view of all but the first member of this Item, if this Item is a non-empty Record; otherwise returns an empty Record if this Item is not a Record, or if this Item is itself an empty Record.

    • body

      public abstract Value body()
      Returns the flattened tail of this Item. Used to recursively deconstruct a structure, terminating with its last Value, rather than a unary Record containing its last value, if the structure ends with a Value member.

    • length

      public abstract int length()
      Returns the number of members contained in this Item, if this Item is a Record; otherwise returns 0 if this Item is not a Record.

    • contains

      public abstract boolean contains(Item item)
      Returns true if this Item is a Record that has a member equal to item; otherwise returns false if this Item is not a Record, or if this Item is a Record, but has no member equal to item.

    • containsKey

      public abstract boolean containsKey(Value key)
      Returns true if this Item is a Record that has a Field member with a key that is equal to the given key; otherwise returns false if this Item is not a Record, or if this Item is a Record, but has no Field member with a key equal to the given key.

    • containsKey

      public abstract boolean containsKey(String key)
      Returns true if this Item is a Record that has a Field with a Text key whose string value is equal to the given key; otherwise returns false if this Item is not a Record, or if this Item is a Record, but has no Field member with a Text key whose string value equals the given key. Equivalent to containsKey(Value), but avoids boxing the key string into a Text value.

    • containsValue

      public abstract boolean containsValue(Value value)
      Returns true if this Item is a Record that has a Field member with a value that is equal to the given value; otherwise returns false if this Item is not a Record, or if this Item is a Record, but has no Field member with a value equal to the given value.

    • get

      public abstract Value get(Value key)
      Returns the value of the last Field member of this Item whose key is equal to the given key; returns Absent if this Item is not a Record, or if this Item is a Record, but has no Field member with a key equal to the given key.

    • get

      public abstract Value get(String key)
      Returns the value of the last Field member of this Item with a Text key whose string value is equal to the given key; returns Absent if this Item is not a Record, or if this Item is a Record, but has no Field member with a Text key whose string value equals the given key. Equivalent to get(Value), but avoids boxing the key string into a Text value.

    • getAttr

      public abstract Value getAttr(Text key)
      Returns the value of the last Attr member of this Item whose key is equal to the given key; returns Absent if this Item is not a Record, or if this Item is a Record, but has no Attr member with a key equal to the given key.

    • getAttr

      public abstract Value getAttr(String key)
      Returns the value of the last Attr member of this Item with a Text key whose string value is equal to the given key; returns Absent if this Item is not a Record, or if this Item is a Record, but has no Attr member with a Text key whose string value equals the given key. Equivalent to getAttr(Text), but avoids boxing the key string into a Text value.

    • getSlot

      public abstract Value getSlot(Value key)
      Returns the value of the last Slot member of this Item whose key is equal to the given key; returns Absent if this Item is not a Record, or if this Item is a Record, but has no Slot member with a key equal to the given key.

    • getSlot

      public abstract Value getSlot(String key)
      Returns the value of the last Slot member of this Item with a Text key whose string value is equal to the given key; returns Absent if this Item is not a Record, or if this Item is a Record, but has no Slot member with a Text key whose string value equals the given key. Equivalent to getSlot(Value), but avoids boxing the key string into a Text value.

    • getField

      public abstract Field getField(Value key)
      Returns the last Field member of this Item whose key is equal to the given key; returns null if this Item is not a Record, or if this Item is a Record, but has no Field member with a key equal to the given key.

    • getField

      public abstract Field getField(String key)
      Returns the last Field member of this Item with a Text key whose string value is equal to the given key; returns null if this Item is not a Record, or if this Item is a Record, but has no Field member with a Text key whose string value equals the given key. Equivalent to getField(Value), but avoids boxing the key string into a Text value.

    • getItem

      public abstract Item getItem(int index)
      Returns the member of this Item at the given index, if this Item is a Record, and the index is greater than or equal to zero, and less than the length of the Record; otherwise returns Absent if this Item is not a Record, or if this Item is a Record, but the index is out of bounds.

    • updated

      public Record updated(Value key, Value value)

    • updated

      public Record updated(Value key, String value)

    • updated

      public Record updated(Value key, int value)

    • updated

      public Record updated(Value key, long value)

    • updated

      public Record updated(Value key, float value)

    • updated

      public Record updated(Value key, double value)

    • updated

      public Record updated(Value key, boolean value)

    • updated

      public Record updated(String key, Value value)

    • updated

      public Record updated(String key, String value)

    • updated

      public Record updated(String key, int value)

    • updated

      public Record updated(String key, long value)

    • updated

      public Record updated(String key, float value)

    • updated

      public Record updated(String key, double value)

    • updated

      public Record updated(String key, boolean value)

    • updatedAttr

      public Record updatedAttr(Text key, Value value)

    • updatedAttr

      public Record updatedAttr(Text key, String value)

    • updatedAttr

      public Record updatedAttr(Text key, int value)

    • updatedAttr

      public Record updatedAttr(Text key, long value)

    • updatedAttr

      public Record updatedAttr(Text key, float value)

    • updatedAttr

      public Record updatedAttr(Text key, double value)

    • updatedAttr

      public Record updatedAttr(Text key, boolean value)

    • updatedAttr

      public Record updatedAttr(String key, Value value)

    • updatedAttr

      public Record updatedAttr(String key, String value)

    • updatedAttr

      public Record updatedAttr(String key, int value)

    • updatedAttr

      public Record updatedAttr(String key, long value)

    • updatedAttr

      public Record updatedAttr(String key, float value)

    • updatedAttr

      public Record updatedAttr(String key, double value)

    • updatedAttr

      public Record updatedAttr(String key, boolean value)

    • updatedSlot

      public Record updatedSlot(Value key, Value value)

    • updatedSlot

      public Record updatedSlot(Value key, String value)

    • updatedSlot

      public Record updatedSlot(Value key, int value)

    • updatedSlot

      public Record updatedSlot(Value key, long value)

    • updatedSlot

      public Record updatedSlot(Value key, float value)

    • updatedSlot

      public Record updatedSlot(Value key, double value)

    • updatedSlot

      public Record updatedSlot(Value key, boolean value)

    • updatedSlot

      public Record updatedSlot(String key, Value value)

    • updatedSlot

      public Record updatedSlot(String key, String value)

    • updatedSlot

      public Record updatedSlot(String key, int value)

    • updatedSlot

      public Record updatedSlot(String key, long value)

    • updatedSlot

      public Record updatedSlot(String key, float value)

    • updatedSlot

      public Record updatedSlot(String key, double value)

    • updatedSlot

      public Record updatedSlot(String key, boolean value)

    • appended

      public Record appended(Item item)

    • appended

      public Record appended(String item)

    • appended

      public Record appended(int item)

    • appended

      public Record appended(long item)

    • appended

      public Record appended(float item)

    • appended

      public Record appended(double item)

    • appended

      public Record appended(boolean item)

    • appended

      public Record appended(Object... items)

    • prepended

      public Record prepended(Item item)

    • prepended

      public Record prepended(String item)

    • prepended

      public Record prepended(int item)

    • prepended

      public Record prepended(long item)

    • prepended

      public Record prepended(float item)

    • prepended

      public Record prepended(double item)

    • prepended

      public Record prepended(boolean item)

    • prepended

      public Record prepended(Object... items)

    • removed

      public abstract Item removed(Value key)

    • removed

      public abstract Item removed(String key)

    • concat

      public Record concat(Item that)

    • conditional

      public abstract Item conditional(Item thenTerm, Item elseTerm)

    • or

      public abstract Item or(Item that)

    • and

      public abstract Item and(Item that)

    • bitwiseOr

      public abstract Item bitwiseOr(Item that)

    • bitwiseXor

      public abstract Item bitwiseXor(Item that)

    • bitwiseAnd

      public abstract Item bitwiseAnd(Item that)

    • lt

      public Item lt(Item that)

    • le

      public Item le(Item that)

    • eq

      public Item eq(Item that)

    • ne

      public Item ne(Item that)

    • ge

      public Item ge(Item that)

    • gt

      public Item gt(Item that)

    • plus

      public abstract Item plus(Item that)

    • minus

      public abstract Item minus(Item that)

    • times

      public abstract Item times(Item that)

    • divide

      public abstract Item divide(Item that)

    • modulo

      public abstract Item modulo(Item that)

    • not

      public abstract Item not()

    • bitwiseNot

      public abstract Item bitwiseNot()

    • negative

      public abstract Item negative()

    • positive

      public abstract Item positive()

    • inverse

      public abstract Item inverse()

    • invoke

      public Item invoke(Value args)

    • lambda

      public abstract Value lambda(Value template)

    • filter

      public Selector filter()

    • filter

      public Selector filter(Item predicate)

    • max

      public Item max(Item that)

    • min

      public Item min(Item that)

    • evaluate

      public Item evaluate(Interpreter interpreter)

    • evaluate

      public Item evaluate(Item scope)

    • substitute

      public Item substitute(Interpreter interpreter)

    • substitute

      public Item substitute(Item scope)

    • stringValue

      public abstract String stringValue()
      Converts this Item into a String value, if possible.
      Throws:
      UnsupportedOperationException - if this Item can't be converted into a String value.

    • stringValue

      public abstract String stringValue(String orElse)
      Converts this Item into a String value, if possible; otherwise returns orElse if this Item can't be converted into a string value.

    • byteValue

      public abstract byte byteValue()
      Converts this Item into a primitive byte value, if possible.
      Throws:
      UnsupportedOperationException - if this Item can't be converted into a primitive byte value.

    • byteValue

      public abstract byte byteValue(byte orElse)
      Converts this Item into a primitive byte value, if possible; otherwise returns orElse if this Item can't be converted into a primitive byte value.

    • shortValue

      public abstract short shortValue()
      Converts this Item into a primitive short value, if possible.
      Throws:
      UnsupportedOperationException - if this Item can't be converted into a primitive short value.

    • shortValue

      public abstract short shortValue(short orElse)
      Converts this Item into a primitive short value, if possible; otherwise returns orElse if this Item can't be converted into a primitive short value.

    • intValue

      public abstract int intValue()
      Converts this Item into a primitive int value, if possible.
      Throws:
      UnsupportedOperationException - if this Item can't be converted into a primitive int value.

    • intValue

      public abstract int intValue(int orElse)
      Converts this Item into a primitive int value, if possible; otherwise returns orElse if this Item can't be converted into a primitive int value.

    • longValue

      public abstract long longValue()
      Converts this Item into a primitive long value, if possible.
      Throws:
      UnsupportedOperationException - if this Item can't be converted into a primitive long value.

    • longValue

      public abstract long longValue(long orElse)
      Converts this Item into a primitive long value, if possible; otherwise returns orElse if this Item can't be converted into a primitive long value.

    • floatValue

      public abstract float floatValue()
      Converts this Item into a primitive float value, if possible.
      Throws:
      UnsupportedOperationException - if this Item can't be converted into a primitive float value.

    • floatValue

      public abstract float floatValue(float orElse)
      Converts this Item into a primitive float value, if possible; otherwise returns orElse if this Item can't be converted into a primitive float value.

    • doubleValue

      public abstract double doubleValue()
      Converts this Item into a primitive double value, if possible.
      Throws:
      UnsupportedOperationException - if this Item can't be converted into a primitive double value.

    • doubleValue

      public abstract double doubleValue(double orElse)
      Converts this Item into a primitive double value, if possible; otherwise returns orElse if this Item can't be converted into a primitive double value.

    • integerValue

      public abstract BigInteger integerValue()
      Converts this Item into a BigInteger value, if possible.
      Throws:
      UnsupportedOperationException - if this Item can't be converted into a BigInteger value.

    • integerValue

      public abstract BigInteger integerValue(BigInteger orElse)
      Converts this Item into a BigInteger value, if possible; otherwise returns orElse if this Item can't be converted into a BigInteger value.

    • numberValue

      public abstract Number numberValue()
      Converts this Item into a Number object, if possible.
      Throws:
      UnsupportedOperationException - if this Item can't be converted into a Number object.

    • numberValue

      public abstract Number numberValue(Number orElse)
      Converts this Item into a Number object, if possible; otherwise returns orElse if this Item can't be converted into a Number object.

    • charValue

      public abstract char charValue()
      Converts this Item into a primitive char value, if possible.
      Throws:
      UnsupportedOperationException - if this Item can't be converted into a primitive char value.

    • charValue

      public abstract char charValue(char orElse)
      Converts this Item into a primitive char value, if possible; otherwise returns orElse if this Item can't be converted into a primitive char value.

    • booleanValue

      public abstract boolean booleanValue()
      Converts this Item into a primitive boolean value, if possible.
      Throws:
      UnsupportedOperationException - if this Item can't be converted into a primitive boolean value.

    • booleanValue

      public abstract boolean booleanValue(boolean orElse)
      Converts this Item into a primitive boolean value, if possible; otherwise returns orElse if this Item can't be converted into a primitive boolean value.

    • cast

      public <T> T cast(Form<T> form)

    • cast

      public <T> T cast(Form<T> form, T orElse)

    • coerce

      public <T> T coerce(Form<T> form)

    • coerce

      public <T> T coerce(Form<T> form, T orElse)

    • isAliased

      public abstract boolean isAliased()

    • isMutable

      public abstract boolean isMutable()

    • alias

      public abstract void alias()

    • branch

      public abstract Item branch()

    • commit

      public abstract Item commit()
      Flags this Item as immutable, recursively if it is a Record, then returns this Item.

    • precedence

      public int precedence()

    • iterator

      public Iterator<Item> iterator()
      Specified by:
      iterator in interface Iterable<Item>

    • typeOrder

      public abstract int typeOrder()
      Returns the heterogeneous sort order of this Item. Used to impose a total order on the set of all items. When comparing two items of different types, the items order according to their typeOrder.

    • compareTo

      public abstract int compareTo(Item other)
      Specified by:
      compareTo in interface Comparable<Item>

    • keyEquals

      public abstract boolean keyEquals(Object key)

    • equals

      public abstract boolean equals(Object other)
      Overrides:
      equals in class Object

    • hashCode

      public abstract int hashCode()
      Overrides:
      hashCode in class Object

    • debug

      public abstract <T> Output<T> debug(Output<T> output)
      Description copied from interface: Debug
      Writes a developer readable, debug-formatted string representation of this object to output.
      Specified by:
      debug in interface Debug
      Returns:
      the continuation of the output.

    • display

      public <T> Output<T> display(Output<T> output)
      Description copied from interface: Display
      Writes a human readable, display-formatted string representation of this object to output.
      Specified by:
      display in interface Display
      Returns:
      the continuation of the output.

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • empty

      public static Item empty()

    • extant

      public static Item extant()

    • absent

      public static Item absent()

    • fromObject

      public static Item fromObject(Object object)

    • globalScope

      public static Item globalScope()