Module io.jenetics.ext

Package io.jenetics.ext.rewriting

Class TRS<V>

java.lang.Object

io.jenetics.ext.rewriting.TRS<V>

All Implemented Interfaces:

TreeRewriter<V>, Serializable

public final class TRS<V>
extends Object
implements TreeRewriter<V>, Serializable

This class represents a Tree Rewrite System, which consists of a set of Tree Rewrite Rules.

final TRS<String> trs = TRS.parse(
    "add(0,$x) -> $x",
    "add(S($x),$y) -> S(add($x,$y))",
    "mul(0,$x) -> 0",
    "mul(S($x),$y) -> add(mul($x,$y),$y)"
);

// Converting the input tree into its normal form.
final TreeNode<String> tree = TreeNode.parse("add(S(0),S(mul(S(0),S(S(0)))))");
trs.rewrite(tree);
assert tree.equals(TreeNode.parse("S(S(S(S(0))))"));

Since:

5.0

Version:

5.0

See Also:

• TreeRewriteRule
• TRS
• Serialized Form

Constructor Summary

Constructors

Constructor	Description
TRS(ISeq<TreeRewriteRule<V>> rules)	Create a new TRS from the given rewrite rules.

Method Summary

Modifier and Type	Method	Description
boolean	equals(Object obj)
int	hashCode()
<B> TRS<B>	map(Function<? super V,? extends B> mapper)	Maps this TRS from type V to type B.
static TRS<String>	parse(String... rules)	Create a new TRS from the given rewrite rules.
static <V> TRS<V>	parse(Function<? super String,? extends V> mapper, String... rules)	Create a new TRS from the given rewrite rules and type mapper.
int	rewrite(TreeNode<V> tree, int limit)	Applies the rewriting to the given (mutable) tree.
String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface io.jenetics.ext.rewriting.TreeRewriter

rewrite

Constructor Details

TRS

public TRS(ISeq<TreeRewriteRule<V>> rules)

Create a new TRS from the given rewrite rules.

Parameters:

rules - the rewrite rules the TRS consists of

Throws:

NullPointerException - if the given rules are null

IllegalArgumentException - if the given rules sequence is empty

Method Details

rewrite

public int rewrite(TreeNode<V> tree,
 int limit)

Description copied from interface: TreeRewriter

Applies the rewriting to the given (mutable) tree. The tree rewrite is done in place. Via the limit parameter, the termination of the tree-rewrite process can be guaranteed.

Specified by:

rewrite in interface TreeRewriter<V>

Parameters:

tree - the tree to be rewritten

limit - the maximal number this rewrite rule is applied to the given tree. This guarantees the termination of the rewrite method.

Returns:

the number of rewrites applied to the input tree

map

public <B> TRS<B> map(Function<? super V,? extends B> mapper)

Maps this TRS from type V to type B.

Type Parameters:

B - the target type

Parameters:

mapper - the type mapper

Returns:

a new TRS for the mapped type

Throws:

NullPointerException - if the mapper is null

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object

parse

public static <V> TRS<V> parse(Function<? super String,? extends V> mapper,
 String... rules)

Create a new TRS from the given rewrite rules and type mapper.

Type Parameters:

V - the tree value type the rewriter is working on

Parameters:

mapper - the tree value type mapper

rules - the rewrite rules

Returns:

a new TRS

Throws:

NullPointerException - if one of the arguments is null

IllegalArgumentException - if the given rules sequence is empty

parse

public static TRS<String> parse(String... rules)

Create a new TRS from the given rewrite rules.

Parameters:

rules - the rewrite rules

Returns:

a new TRS

Throws:

NullPointerException - if one of the arguments is null

IllegalArgumentException - if the given rules sequence is empty