uk.ac.man.cs.rainbow.datamodel
Class Data

java.lang.Object
  |
  +--uk.ac.man.cs.rainbow.rapa.data.Expression
        |
        +--uk.ac.man.cs.rainbow.datamodel.Data

All Implemented Interfaces:

Argument, Serializable, Value, VariableContainer

Direct Known Subclasses:

Data.List, Data.Union, Data.Untyped, Data.Word

public abstract class Data

extends Expression

The core class of data values. The major specialisations are nested top-level classes for convenience of writing.

Of interest are:

• Data.Word - word (enumerable) values.
• Data.List - list (structured/compound) values.
• Data.Union - union (tagged/discriminated) values.
• Data.Untyped - superclass of untypable values.

See Also:

Type, Serialized Form

Inner Class Summary

static interface	Data.Comparable Indicate that two data values can be compared for relative order.
static class	Data.List Compound "list" datatypes.
static class	Data.Union Union datatypes.
static class	Data.Untyped The superclass of all Untypeable data classes.
static class	Data.Word Basic "word" datatypes.

Method Summary

Value	apply(Unifier u) Apply a unifier to this value to get a new value.
abstract Data	cast(Type t) Return a new data value that has the given type.
abstract boolean	equals(Data d) Standardised equality defined over data values with equal types.
boolean	equals(Object o)
boolean	equals(Value o) Standard equality lifted to handle any argument object including data objects with non-equal types.
Type	getResultType()
Type	getType() Get the type of the data value.
int	hashCode() Hash-code generator.
boolean	hasVariable()
static void	main(String[] args) Test code...
boolean	occurs(Substitution s, Variable v) Check whether the variable occurs in this value under the given substitution.
static Data	parse(String s) Attempts to parse the given string to produce a data value.
static Data	parse(String s, Hashtable context) Attempts to parse the given string (in context) to produce a data value.
Value	subst(Substitution s) Apply a substitution to this value to get a new value.
abstract String	toString() Print the data value.
String	typedString() Print the data value with a type annotation.
Substitution	unify(Substitution s, Value val) Get the substitution which unifies this value with the given value, after applying the given substitution.

Methods inherited from class uk.ac.man.cs.rainbow.rapa.data.Expression

compatableWith, evaluate, getNodeType, subst

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Method Detail

toString

public abstract String toString()

Print the data value.

Overrides:

toString in class Object

getType

public Type getType()

Get the type of the data value. Returns null for untyped data values.

typedString

public String typedString()

Print the data value with a type annotation. The type annotation is omitted if there is no type available.

cast

public abstract Data cast(Type t)
                   throws TypeException

Return a new data value that has the given type.

Throws:

TypeException - Thrown if the data value being cast from (or some part of it) disgrees with the type (or type component) that is being specified for it.

equals

public abstract boolean equals(Data d)

Standardised equality defined over data values with equal types. Implemented by concrete subclasses.

equals

public boolean equals(Value o)

Standard equality lifted to handle any argument object including data objects with non-equal types.

Overrides:

equals in class Expression

equals

public boolean equals(Object o)

Overrides:

equals in class Expression

hashCode

public int hashCode()

Hash-code generator. Implemented so that data values that print the same way have the same hashCode (and ought to satisfy equals() too...)

Overrides:

hashCode in class Object

parse

public static Data parse(String s)
                  throws TypeException

Attempts to parse the given string to produce a data value.

parse

public static Data parse(String s,
                         Hashtable context)
                  throws TypeException

Attempts to parse the given string (in context) to produce a data value.

hasVariable

public boolean hasVariable()

apply

public Value apply(Unifier u)

Description copied from interface: Value

Apply a unifier to this value to get a new value.

Overrides:

apply in class Expression

subst

public Value subst(Substitution s)

Description copied from interface: Value

Apply a substitution to this value to get a new value.

Overrides:

subst in class Expression

occurs

public boolean occurs(Substitution s,
                      Variable v)

Description copied from interface: Value

Check whether the variable occurs in this value under the given substitution.

Overrides:

occurs in class Expression

unify

public Substitution unify(Substitution s,
                          Value val)
                   throws NotUnifiable

Description copied from interface: Value

Get the substitution which unifies this value with the given value, after applying the given substitution.

Overrides:

unify in class Expression

Following copied from interface: uk.ac.man.cs.rainbow.rapa.data.Value

Parameters:

subst - The substitution to apply first.

val - The value to unify with this value.

Returns:

The substitution that is the combination of the given substitution and whatever extra substitutions are necessary to unify the two values.

Throws:

NotUnifiable - If the two values cannot be unified.

getResultType

public Type getResultType()

Overrides:

getResultType in class Expression

main

public static void main(String[] args)

Test code...