Package net.sourceforge.pmd.lang.java.types

Class Substitution

java.lang.Object

net.sourceforge.pmd.lang.java.types.Substitution

All Implemented Interfaces:

Function<SubstVar,JTypeMirror>

public final class Substitution
extends Object

A function from SubstVars to types. Applying it to a type replaces the occurrences of some variables with other types. This can be done with TypeOps.subst(JTypeMirror, Function).

Field Summary

Fields

Modifier and Type	Field	Description
static Substitution	EMPTY	The empty substitution maps every type variable to itself.

Method Summary

Modifier and Type	Method	Description
Substitution	andThen(Substitution other)	Returns a composed substitution that first applies this substitution to its input, and then applies the after substitution to the result.
@NonNull JTypeMirror	apply(@NonNull SubstVar var)	Returns the type with which the given variable should be replaced.
static Substitution	erasing(List<? extends JTypeVar> tparams)	Returns a substitution that replaces the given type variables with their erasure.
protected Map<T,R>	getMap()
boolean	isEmpty()
static boolean	isEmptySubst(Function<?,?> m)
static Substitution	mapping(List<? extends SubstVar> from, List<? extends JTypeMirror> to)	Builds a substitution where the mapping from vars to types is defined by the correspondence between the two lists.
Substitution	plus(SubstVar from, JTypeMirror to)	Maps the given variable to the given type.
String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.function.Function

andThen, compose

Field Detail

EMPTY

public static final Substitution EMPTY

The empty substitution maps every type variable to itself.

Method Detail

isEmptySubst

public static boolean isEmptySubst(Function<?,?> m)

apply

public @NonNull JTypeMirror apply(@NonNull SubstVar var)

Returns the type with which the given variable should be replaced.

andThen

public Substitution andThen(Substitution other)

Returns a composed substitution that first applies this substitution to its input, and then applies the after substitution to the result.

Given two substitutions S1, S2 and a type t:
subst(subst(t, S1), S2) == subst(t, S1.andThen(S2))

For example:

  S1 = [ T -> A<U> ]
  S2 = [ U -> B<V> ]

  subst(List<T>, S1)    = List<A<U>>
  subst(List<A<U>>, S2) = List<A<B<V>>>

  S1.andThen(S2) = [ T -> A<B<V>>, U -> B<V> ]
 

Parameters:

other - the function to apply after this function is applied

Returns:

a composed substitution

Throws:

NullPointerException - if other is null

plus

public Substitution plus(SubstVar from,
                         JTypeMirror to)

Maps the given variable to the given type. This does not apply this substitution to the type mirror.

mapping

public static Substitution mapping(List<? extends SubstVar> from,
                                   List<? extends JTypeMirror> to)

Builds a substitution where the mapping from vars to types is defined by the correspondence between the two lists.

If there are no vars to be mapped, then no substitution is returned even though some types might have been supplied.

Throws:

IllegalArgumentException - If the two lists are of different lengths

NullPointerException - If any of the two lists is null

erasing

public static Substitution erasing(List<? extends JTypeVar> tparams)

Returns a substitution that replaces the given type variables with their erasure.

Parameters:

tparams - Type variables to erase

getMap

protected Map<T,R> getMap()

isEmpty

public boolean isEmpty()

toString

public String toString()

Overrides:

toString in class Object